WO2007013216A1 - Azimuth calculation device, azimuth calculation method, azimuth calculation program, and recording medium - Google Patents

Abstract

There is provided an azimuth calculation device for correcting an output of an angular velocity sensor by a correction coefficient and calculating an azimuth of a moving body according to the obtained value. An output value from the angular velocity sensor is acquired by a sensor value acquisition unit (101). The output value acquired is inputted to a judgment unit (102) and it is judged whether the moving body turns leftward or rightward. According to the result of the judgment and the output value, one of the correction coefficients is acquired by a coefficient acquisition unit (103). By using the acquired correction coefficient, an angular velocity calculation unit (104) calculates the angular velocity of the moving body according to the rightward or leftward turn of the moving body. According to the angular velocity obtained by the calculation, an azimuth calculation unit (105) calculates the azimuth of the moving body.

Description

 Specification

 Direction calculation apparatus, direction calculation method, direction calculation program, and recording medium

 [0001] The present invention relates to a direction calculation device, a direction calculation method, a direction calculation program, and a recording medium that can be applied to a navigation device mounted on a moving body such as a vehicle. However, the use of the present invention is not limited to the navigation device described above.

 Background art

 [0002] For example, there is a navigation device mounted on a vehicle or the like that calculates an angular velocity and a bending direction of the vehicle based on an output value from an angular velocity sensor mounted on the vehicle. Since the sensitivity characteristics of the angular velocity sensor may differ depending on the bending direction of the vehicle, the influence of the bending direction of the vehicle on the sensitivity characteristic of the angular velocity sensor is eliminated by changing the correction coefficient according to the bending direction. (For example, see Patent Document 1 below.) O

 [0003] Patent Document 1: JP-A-8-304090

 Disclosure of the invention

 Problems to be solved by the invention

[0004] By the way, in the technique described in Patent Document 1 described above, when an angular velocity equal to or greater than a predetermined threshold is calculated, it is determined that the sensitivity characteristic of the angular velocity sensor is affected, and the angular velocity is corrected. However, the difference in the sensitivity characteristics of the angular velocity sensor due to the difference in the bending direction may occur even if the angular velocity is less than a predetermined threshold value. Even if the technique described in Patent Document 1 is used, the vehicle at the time of bending is different. Depending on the speed, if the error in the calculated angular speed cannot be corrected, there is an example of the problem.

 Means for solving the problem

[0005] The azimuth calculating apparatus according to the invention of claim 1 includes a sensor value acquiring unit that acquires an output value of the angular velocity sensor force, and a bending direction of the moving body based on the output value acquired by the sensor value acquiring unit. Based on the determination result determined by the determination unit and the output value! /, According to the angular velocity in each bending direction of the moving body. Coefficient acquisition means for acquiring the correction coefficient according to the output value from a plurality of set correction coefficients, and the angular velocity of the mobile object according to the bending direction of the mobile object based on the output value An angular velocity calculating means for calculating using the correction coefficient acquired by the coefficient acquiring means, and an azimuth calculating means for calculating the azimuth of the moving body based on the angular velocity calculated by the angular velocity calculating means. It is characterized by that.

 [0006] The azimuth calculation method according to the invention of claim 4 includes a sensor value acquisition step of acquiring an output value of the angular velocity sensor force, and a moving object based on the output value acquired by the sensor value acquisition step. A determination step for determining the bending direction, and a plurality of values set according to the angular velocity for each bending direction of the moving body based on the determination result and the output value determined by the determination step. A coefficient acquisition step of acquiring the correction coefficient according to the output value from the correction coefficient, and an angular velocity of the mobile body according to the bending direction of the mobile body based on the output value by the coefficient acquisition step. An angular velocity calculating step for calculating using the obtained correction coefficient, and an azimuth calculating step for calculating the azimuth of the moving body based on the angular velocity calculated by the angular velocity calculating step.

[0007] An orientation calculation program according to the invention of claim 5 causes a computer to execute the orientation calculation method according to claim 4.

[0008] A recording medium according to a sixth aspect of the invention is characterized in that the azimuth calculation program according to the fifth aspect is recorded so as to be readable by a computer.

 Brief Description of Drawings

 FIG. 1 is a block diagram showing a functional configuration of an azimuth calculation apparatus according to the present embodiment of the present invention.

 [FIG. 2] FIG. 2 is a flowchart showing the processing contents of the azimuth calculating apparatus according to the present embodiment of the present invention.

 FIG. 3 is a block diagram showing a hardware configuration of the navigation device in the present embodiment of the present invention.

 FIG. 4 is a functional block diagram showing a specific configuration of an azimuth calculation unit and a correction processing unit in the present embodiment of the present invention.

[FIG. 5] FIG. 5 explains the sensitivity change caused by the sensitivity characteristic of the angular velocity sensor. FIG.

 [FIG. 6] FIG. 6 is an explanatory diagram for explaining the sensitivity change caused by the sensitivity characteristic of the angular velocity sensor.

 [FIG. 7] FIG. 7 is an explanatory diagram for explaining a sensitivity change caused by sensitivity characteristics of the angular velocity sensor.

 [FIG. 8] FIG. 8 is an explanatory diagram for explaining the sensitivity change caused by the sensitivity characteristics of the angular velocity sensor.

 [FIG. 9] FIG. 9 is a flowchart for explaining the contents of the processing of the navigation apparatus according to the embodiment of the present invention.

 FIG. 10 is an explanatory diagram showing a correction coefficient table.

 FIG. 11 is an explanatory diagram showing a specific example of a correction coefficient table.

 Explanation of symbols

[0010] 101 sensor value acquisition unit

 102 Judgment part

 103 Coefficient acquisition unit

 104 Angular velocity calculator

 105 Direction calculator

 106 Azimuth acquisition unit

 107 Correction section

 BEST MODE FOR CARRYING OUT THE INVENTION

 Hereinafter, preferred embodiments of an azimuth calculation device, an azimuth calculation method, a direction calculation program, and a recording medium according to the present invention will be described in detail with reference to the accompanying drawings. The azimuth calculation device of the present invention can be applied to, for example, a navigation device mounted on a moving body such as a vehicle. Hereinafter, in the present embodiment, the case where the moving body is a vehicle will be described.

 [0012] (Functional configuration of bearing calculation device)

First, a functional configuration of the azimuth calculation apparatus according to the present embodiment of the present invention will be described. FIG. 1 is a block diagram showing a functional configuration of the bearing calculation apparatus according to the embodiment of the present invention. FIG. The azimuth calculation apparatus includes a sensor value acquisition unit 101, a determination unit 102, a coefficient acquisition unit 103, an angular velocity calculation unit 104, an azimuth calculation unit 105, an azimuth acquisition unit 106, and a correction unit 107. Yes.

 [0013] First, the sensor value acquisition unit 101 acquires an output value of the angular velocity sensor force provided in the navigation device mounted on the vehicle. The angular velocity sensor is a sensor whose output changes according to the angular velocity at the time of turning of the vehicle, and can be realized by a vibration gyro sensor, for example. The output value of the angular velocity sensor force is a value obtained by subtracting the zero point (offset) voltage value from the voltage value output from the angular velocity sensor.

 [0014] Here, the zero point (offset) voltage value is a value obtained by correcting the amount of temperature drift with respect to the output value of the angular velocity sensor force when the vehicle is stationary or the output value of the angular velocity sensor force when the vehicle goes straight. is there. Hereinafter, in the present embodiment, a value obtained by subtracting a zero point (offset) voltage value from the voltage value force output from the angular velocity sensor will be described as an output value of the angular velocity sensor force.

 [0015] The sensor value acquisition unit 101 acquires an output value from the angular velocity sensor, for example, at a constant sampling period T interval. Specifically, for example, the zero (offset) voltage value is gy

 If the voltage value output from the angular velocity sensor at sampling time nT is gy, the output value from the angular velocity sensor is (gy—gy

 n 0).

 Further, the determination unit 102 outputs the angular velocity sensor force output value (gy -gy) acquired by the sensor value acquisition unit 101.

 Based on n 0, the turning direction of the vehicle is determined. Specifically, determination unit 1

02 is, for example, a right turn when the angular velocity G ′ (gy—gy) force before correction, which is obtained by multiplying the output value from the angular velocity sensor by a gain value, and when it is a negative value, Turn left, etc. n 0

 Thus, the turning direction of the vehicle is determined.

[0017] Also, the coefficient acquisition unit 103 responds to the angular velocity G '(gy-gy) before correction based on the determination result determined by the determination unit 102 and the angular velocity G' (gy-gy) before correction. Correction n 0 n 0

Get one coefficient Gk. A plurality of correction coefficients Gk to be acquired by the coefficient acquisition unit 103 are set for each bending direction and angular velocity of the vehicle. More specifically, a plurality of correction coefficients Gk to be acquired by the coefficient acquisition unit 103 are set according to the angular velocity when the vehicle turns right. Is set.

 [0018] Further, the correction coefficient Gk to be acquired by the coefficient acquisition unit 103 is set stepwise for each predetermined angular velocity range. This angular velocity range is set so that the interval decreases as the angular velocity before correction increases. The predetermined angular velocity range may be set at regular intervals, for example, l [degZ s]!

 In addition, the angular velocity calculation unit 104 calculates the angular velocity of the vehicle according to the bending direction of the vehicle using the correction coefficient G k acquired by the coefficient acquisition unit 103 based on the output value from the angular velocity sensor. To do. Specifically, the angular velocity calculation unit 104 obtains the angular velocity G ′ (gy−gy) before correction at the sampling time nT, for example, by the coefficient acquisition unit 103 and n 0.

 In addition, by multiplying the correction coefficient Gk at the sampling time (n-1) T,

 Calculate the current angular velocity ω = Gk 'G' (gy—gy) at the pulling time nT.

 n n-1 n 0

In addition, the azimuth calculation unit 105 calculates the azimuth of the vehicle based on the current angular velocity ω _η calculated by the angular velocity calculation unit 104. Specifically, for example, when the output value from the angular velocity sensor is acquired at a certain sampling period Τ interval, the azimuth calculation unit 105 first calculates the current angular velocity ω at the sampling time nT as the sampling period. Accumulate with firewood. As a result, the amount of angular displacement (hereinafter referred to as “relative orientation”) ΔΘg from the sampling time (η−1) Τ to the sampling time nT is calculated. Then, the calculated relative orientation Δ 0 g is added to the vehicle orientation Θ g at the sampling time (n−1) T. N n-1

 Thus, the vehicle direction at sampling time nT (hereinafter referred to as “calculated vehicle direction” 5) 0 g = 0 g + A 0 g

 n n-1 n is calculated.

The direction acquisition unit 106 acquires a direction indicating the traveling direction of the vehicle (hereinafter referred to as “acquired vehicle direction”). Here, the direction acquisition unit 106 acquires the vehicle direction acquired by a method different from the vehicle direction calculated by the direction calculation unit 105. Specifically, the direction based on the east, west, north, and south is acquired. More specifically, for example, the azimuth acquisition unit 106 acquires the azimuth 0, of the acquired vehicle using GPS (Global Positioning System). When the direction calculation device can read out the map information, the direction acquisition unit 106 acquires the acquired vehicle direction Θ ′ using the road shape direction data included in the map information. Also good. In this case, the map information is integrated with the bearing calculation device. For example, the external force of the azimuth calculating device may also be read by communication or the like.

 The correction unit 107 corrects the correction coefficient Gk acquired by the coefficient acquisition unit 103 based on the calculated vehicle orientation Θ R and the acquired vehicle orientation Θ. Concrete

 n-1

 Specifically, the correction unit 107 compares the calculated vehicle orientation Θ g and the acquired vehicle orientation Θ, so that the calculated vehicle orientation Θ g is asymptotic to the acquired vehicle orientation Θ. In addition, the correction coefficient Gk is corrected. By correcting the correction coefficient Gk by the correction unit 107

 n-i n— 1

 The corrected correction coefficient Gk obtained together with the other left and right correction coefficients is used for the next calculation of the vehicle direction.

[0023] (Contents of processing of bearing calculation device)

 Next, the processing contents of the azimuth calculation device will be described. FIG. 2 is a flowchart showing the contents of processing of the azimuth calculating apparatus according to the embodiment of the present invention. In the flow chart of FIG. 2, first, the sensor value acquisition unit 101 acquires the output value (gy—gy) of the angular velocity sensor force (step S201), and gains the obtained output value (gy—gy) of the angular velocity sensor force. Multiply by the value G to calculate the uncorrected angular velocity G '(gy—gy)

0 n 0

 (Step S202).

 [0024] Next, based on the angular velocity G ′ (gy—gy) before correction calculated in step S202.

 n 0

 The determination unit 102 determines the turning direction of the vehicle (step S203), and based on the determination result and the angular velocity G ′ (gy -gy) before correction, either the right turn or the left turn is used.

 n 0

 One correction coefficient Gk is acquired from the correction coefficient by the coefficient acquisition unit 103 (step S).

 n-l

 204).

 [0025] Then, the angular velocity G '(gy—gy) before correction calculated in step S202 is

 n 0

 The angular velocity calculation unit 104 multiplies the correction coefficient Gk acquired in step S204.

 n-l

 Thus, the current angular velocity ω of the vehicle according to the turning direction of the vehicle is calculated (step S205), and the calculated vehicle orientation Θ g is calculated based on the calculated current angular velocity ω. Calculated by 105 (step S 206).

On the other hand, the obtained vehicle orientation Θ ′ is obtained by the orientation obtaining unit 106 (step S2 07), and the obtained vehicle orientation 0 ′ and the vehicle direction calculated in step S206 are obtained. Based on the position Θg! /, The correction coefficient Gk obtained in step S204 is converted to the correction unit 10 n n-1

After correcting by 7 (step S208), the series of processing is terminated. The correction coefficient Gk acquired in step S204 is corrected in step S208 to be corrected n-1.

 Updated to later correction factor Gk.

In the above embodiment, the bending determination in step S 203 is performed based on the uncorrected angular velocity G ′ (gy −gy) calculated in step S 202.

 However, the bending determination may be performed based on the sign of the output value gy -gy n 0 from the angular velocity sensor acquired in step S201. In this case, the calculation of the angular velocity in step S202 and the order of the bending determination in step S203 may be interchanged so that the bending determination is performed first.

 [0028] As described above, according to the azimuth calculating apparatus of the present embodiment, the correction coefficient corresponding to the bending direction and the angular velocity of the vehicle is acquired, and the angular velocity of the vehicle calculated using this correction coefficient is obtained. Based on the calculated direction of the vehicle.

 [0029] Here, since a plurality of correction coefficients are set in accordance with the angular velocities for each vehicle bending direction, the angular velocity is always corrected regardless of the vehicle bending direction and the vehicle angular velocity. Is calculated. As a result, the accumulated error of the calculated vehicle direction can be reduced, and the calculation accuracy of the calculated vehicle direction can be improved.

 [0030] In addition, by reducing the cumulative error of the calculated vehicle direction, it takes time until the cumulative error accumulation increases, so it can be obtained using GPS or road shape direction data. The frequency of the calculated vehicle azimuth calibration based on the calculated vehicle azimuth is reduced. As a result, the calculation accuracy of the calculated vehicle orientation can be improved.

 [0031] By the way, the larger the calculated angular velocity is, and the larger the cumulative number of times the calculated vehicle azimuth is is, the greater the influence of errors and the like. According to the above, since the correction coefficient is set for each angular velocity range in which the interval becomes narrower as the angular velocity increases, the accuracy of the calculated angular velocity is prevented from varying due to the difference in the angular velocity. it can. As a result, the accuracy of calculating the angular velocity can be further improved.

[0032] Furthermore, according to the azimuth calculation apparatus of the present embodiment, the calculated azimuth and direction of the vehicle are calculated. Since a plurality of correction coefficients are corrected on the left and right sides based on the obtained vehicle orientation, the calculation accuracy of the angular velocity of the vehicle can be improved. Thereby, it is possible to further improve the accuracy of the azimuth of the vehicle calculated using the angular velocity.

 Example

 [0033] Examples of the present invention will be described below. In this embodiment, for example, an example in which the azimuth calculation device and the azimuth calculation method of the present invention are implemented by a navigation device mounted on a moving body such as a vehicle (including a four-wheeled vehicle and a two-wheeled vehicle) will be described.

[0034] (Hardware configuration of navigation device)

 First, the hardware configuration of the navigation device in this embodiment of the present invention will be described. FIG. 3 is a block diagram showing a hardware configuration of the navigation apparatus in this embodiment of the present invention. The navigation device in this embodiment of the present invention includes a navigation control unit 301, a user operation unit 302, a display unit 303, a recording medium 304, a recording medium decoding unit 305, a guidance sound output unit 306, The communication unit 307, the route search unit 308, the route guidance unit 309, the guidance sound generation unit 310, the speaker 311, the position acquisition unit 312, the direction calculation unit 313, and the correction processing unit 314 are configured. The

 [0035] First, the navigation control unit 301 controls the entire navigation device. The navigation control unit 301 includes, for example, a CPU (Central Processing Unit) that executes predetermined arithmetic processing, a ROM (Read Only Memory) that stores various control programs, and a RAM (Random) that functions as a work area for the CPU. It can be realized by a microcomputer constituted by an Access Memory). In the RAM, for example, correction coefficients used for calculating the angular velocity are stored. As will be described in detail later, the RAM stores a plurality of correction coefficients set in accordance with the angular velocities for each vehicle turning direction. In the present embodiment, correction factors for left turn La ゝ Lb ゝ Lc, ..., Li, ··· and correction factors Ra, Rb, Rc, ···, Ri, ··· for right turn are stored. (Refer to Fig. 4, Fig. 10 and Fig. 11.) o Each correction factor La, Lb, Lc, ···, Li, ··· and Ra, Rb, Rc, ···, Ri, ··· It is memorized so that it can be updated!

[0036] The navigation control unit 301 performs a route search unit 308, a route guide unit 30 when performing route guidance. 9. Input / output information regarding route guidance to / from the guidance sound generation unit 310, and output the resulting information to the display unit 303 and the guidance sound output unit 306.

 [0037] Also, the user operation unit 302 outputs information input by the user such as characters, numerical values, and various instructions to the navigation control unit 301. As the configuration of the user operation unit 302, various known forms such as a push button switch, a touch panel, a keyboard, and a joystick that detect physical pressing Z non-pressing can be employed. The user operation unit 302 may be configured to perform an input operation by voice using a microphone that inputs voice from the outside.

 [0038] The user operation unit 302 may be provided integrally with the navigation device, or may be configured such that the navigation device force can be separated and operated like a remote controller. Of the various forms described above, the user operation unit 302 may be configured in a single or different form, or may be configured in a plurality of forms. The user inputs information by appropriately performing an input operation according to the form of the user operation unit 302. The information input by the operation of the user operation unit 302 includes, for example, a destination (point information of the destination) or a departure place (point information of the departure place) of the route to be searched.

 [0039] In addition to entering the latitude and longitude of each point and the address, the destination or departure point can be entered by specifying the telephone number, genre, keyword, etc. of the destination or departure point facility. Good. By entering the destination or departure point by designating the phone number, keyword, keyword, etc. of the destination or departure point facility, the corresponding facility is searched and the position is set as the destination or departure point. Can be identified. More specifically, these pieces of information are specified as one point on the map based on background type data included in map information recorded on the recording medium 304 described later. In addition, map information may be displayed on the display unit 303, which will be described later in detail, so that one point on the displayed map is specified.

[0040] The display unit 303 includes, for example, a CRT (Cathode Ray Tube), a TFT liquid crystal display, an organic EL (Electroluminescence) display, a plasma display, and the like. Specifically, the display unit 303 can be configured by, for example, a video IZF or a video display device connected to the video IZF. [0041] Specifically, the video IZF is, for example, a graphic controller that controls the entire display device, and a VRAM (Video

RAM) and a control IC that controls the display device display based on image information output from the graphic controller. Display section 303 displays icons, cursors, menus, windows, or various information such as characters and images. The display unit 303 displays map information and route guidance information stored in an HD (Hard Disk).

 [0042] The recording medium 304 records map information, various control programs, various information, and the like in a readable state by a computer. The recording medium 304 accepts writing of information by the recording medium decoding unit 305 and records the written information in a nonvolatile manner. The recording medium 304 can be realized by HD, for example. The direction calculation program is recorded on the recording medium 304 in the present embodiment. The azimuth calculation program is not limited to the one recorded in the recording medium 304.

 [0043] The recording medium 304 is not limited to HD. Instead of HD or in addition to HD, DVD (Digital Versatile Disk), CD (Compact Disk), etc. can be attached to and detached from the recording medium decoding unit 305. Therefore, a medium having portability may be used as the recording medium 304. The recording medium 304 is not limited to DVD and CD, and is removable from the recording medium decoding unit 305 such as CD-ROM (CD-R, CD-RW), MO (Magneto-Optical disk), and memory card. A portable media can also be used.

 [0044] The map information recorded in the recording medium 304 includes background data representing features such as buildings, rivers, and the ground surface, and road shape direction data representing the shape and direction of the road. On the display screen of the display unit 303, it is drawn two-dimensionally or three-dimensionally. Road shape direction data is also used for map matching, for example. The map information recorded on the recording medium 304 is displayed so as to overlap with the vehicle position acquired by the position acquisition unit 312 when the navigation device is guiding a route, for example.

In this embodiment, the map information is recorded on the recording medium 304. However, the present invention is not limited to this. The map information is provided outside the navigation device, not the one recorded with the navigation device hardware. It may be. In this case, the navigation apparatus acquires map information via the network through the communication unit 307, for example. The acquired map information is stored in RAM.

 In addition, the recording medium decoding unit 305 controls reading / writing of information on the recording medium 304. For example, when HD is used as the recording medium 304, the recording medium decoding unit 305 is an HDD (Hard Disk Drive). Similarly, when a DVD or CD (including CD-R and CD-RW) is used as the recording medium 304, the recording medium decoding unit 305 is a DVD drive or a CD drive. When a CD-ROM (CD-R, CD-RW), MO, memory card, etc. is used as the writable and removable recording medium 304, information is written to various recording media and stored in various recording media. A dedicated drive device capable of reading the recorded information is appropriately used as the recording medium decoding unit 305.

 [0047] The guide sound output unit 306 reproduces the guide sound by controlling the output to the connected speaker 311. There may be one speaker 311 or a plurality of speakers 311. Specifically, the guidance sound output unit 306 can be realized by a sound IZF connected to a speaker 311 for sound output. More specifically, the audio IZF performs, for example, a DZA conversion circuit that performs DZA conversion of audio digital information, an amplifier that amplifies an audio analog signal that is output from the DZA conversion circuit, and AZD conversion of audio analog information. It can be configured with AZD conversion circuit and force.

 [0048] In addition, the communication unit 307 receives traffic information such as traffic congestion and traffic regulations regularly (or even irregularly). The traffic information may be received by the communication unit 307 at the timing when the traffic information is distributed from the VICS (Vehicle Information and Communication System) center, or by periodically requesting the traffic information from the VICS center. May be.

[0049] The communication unit 307 can be realized as, for example, an FM tuner, a VICSZ beacon receiver, and other communication devices. The received traffic information is used when searching for a route (including re-searching), for example, for searching for a route that avoids a traffic jam location or a time regulation location. [0050] The ability to omit detailed explanations because it is a well-known technology "VICS" means that traffic information such as traffic jams and traffic regulations that have been edited and processed at the VICS center is sent in real-time and written to navigation devices, etc. 'It is an information communication system that displays graphics. As a method of transmitting traffic information (VICS information) edited and processed at the VICS Center to the navigation device, there is a method of using “beacon” and “FM multiplex broadcasting” installed on each road.

 [0051] "Beacons" include "radio wave beacons" mainly used on expressways and "optical beacons" used on major general roads. When “FM multiplex broadcasting” is used, traffic information in a wide area can be received. When using "Beacon", it is possible to receive necessary traffic information at the place where the vehicle is located, such as detailed information on the most recent road based on the vehicle location.

 [0052] Further, the route search unit 308 uses the map information recorded in the recording medium 304, the VICS information acquired through the communication unit 307, and the like from the departure place (point information of the departure place). Search for the optimal route to the destination (point information of the destination). Here, the optimal route is the route that best meets the conditions specified by the user. In general, there are numerous routes from the starting point to the destination. For this reason, items that are considered in the route search are set to search for a route that meets the conditions.

 [0053] Further, the route guidance unit 309 uses the guidance route information searched by the route search unit 308, the vehicle position information acquired by the position acquisition unit 312, and the recording medium 304 via the recording medium decoding unit 305. Based on the map information obtained, real-time route guidance information is generated. The route guidance information generated at this time may take into account the traffic information received by the communication unit 307! The route guidance information generated by the route guidance unit 309 is output to the display unit 303 via the navigation control unit 301.

 [0054] In addition, guide sound generation section 310 generates tone and voice information corresponding to the pattern.

 That is, based on the route guidance information generated by the route guidance unit 309, the virtual sound source corresponding to the guidance point is set and the voice guidance information is generated. The guidance sound output unit is provided via the navigation control unit 301. Output to 306.

The position acquisition unit 312 is also configured with a GPS receiver and various sensor forces, and acquires information on the current position of the vehicle and direction information indicating the direction (absolute direction) Θ ′ of the vehicle. GP The S receiver receives the radio wave from the GPS satellite and obtains the geometric position with the GPS satellite. GPS is a system that accurately obtains the position on the ground by receiving radio waves from four or more satellites.

 [0056] The GPS receiver specifically includes, for example, an antenna for receiving radio waves from a GPS satellite, a tuner for demodulating the received radio waves, and an arithmetic circuit for calculating the current position based on the demodulated information. (Or program). The azimuth information is not limited to that obtained using the GPS, but may be obtained using road shape azimuth data included in the map information recorded on the recording medium 304. Hereinafter, the absolute orientation Θ ′ is referred to as “acquired absolute orientation Θ ′”.

 It should be noted that the various sensors are various sensors mounted on the vehicle such as a vehicle speed sensor, a travel distance sensor, a tilt sensor, and an angular velocity sensor. When acquiring the vehicle position and direction information, the information output by various sensors mounted on the vehicle is used together with the information obtained by the GPS receiver to obtain the vehicle position with higher accuracy. can do.

 [0058] The vehicle speed sensor detects the number of vehicle speed pulses per rotation of the output side drive shaft of the transmission of the vehicle equipped with the navigation. The mileage sensor calculates the number of pulses per one rotation of the wheel by counting the number of pulses of a pulse signal with a predetermined period output along with the rotation of the wheel, and the mileage information based on the number of pulses per one rotation. Information is output. The inclination sensor detects the inclination angle of the road surface. The angular velocity sensor detects the angular velocity when the vehicle is bent.

 [0059] Specifically, the angular velocity sensor can be realized by a vibration gyro sensor using a piezoelectric element or the like as a detection element, for example. In this case, the angular velocity sensor outputs a voltage value having a magnitude corresponding to the angular velocity at the time of turning of the vehicle. Here, for example, when the output value of the angular velocity sensor force is 2.5 V (specified zero voltage), it indicates that the angular velocity is zero (0 [deg / s]).

[0060] By the way, the angular velocity is zero when the vehicle is stationary or when the vehicle is traveling straight. Generally, the zero voltage measured in such a situation has an effect such as temperature change. In many cases, the value is drifting. For this reason, in this embodiment, the vehicle The value corrected for the effect of temperature drift on the output value of the angular velocity sensor when both are stationary or the output value of the angular velocity sensor force when the vehicle is traveling straight is used as the zero point (offset) voltage value.

 [0061] The angular velocity sensor outputs the detected angular velocity as an analog signal of OV to 5V. The sensitivity of the angular velocity sensor is expressed by the degree of deviation of the angular velocity from the zero (offset) voltage (the specified zero voltage of 2.5 V), and its unit is [mVZdegZsec]. The sensitivity of the angular velocity sensor conforms to the standard specified in the horizontal state, and is adjusted so as to be within a predetermined error. Hereinafter, in this embodiment, a value obtained by subtracting the zero point (offset) voltage value from the voltage value force output from the angular velocity sensor is referred to as an “output value of the angular velocity sensor force”. The output value of the angular velocity sensor force is acquired, for example, every sampling period T interval. The sampling period T can be set to an arbitrary value, specifically, for example, 100 msec.

 [0062] The angular velocity sensor outputs a positive angular velocity corresponding to a clockwise azimuth change, that is, a right turn, as a deviation voltage from 2.5V to the 5V side. On the other hand, this angular velocity sensor outputs a negative angular velocity corresponding to a counterclockwise direction change, that is, a left turn, as a deviation voltage from 2.5V to the OV side. When a vibration gyro is used as the angular velocity sensor, an AZD conversion circuit 420 (see FIG. 4) that performs AZD conversion on an analog voltage value detected by the vibration gyro is further provided.

 [0063] Further, the bearing calculation unit 313 calculates the angular velocity and the bearing based on the output value from the angular velocity sensor. The method for calculating the angular velocity and the direction based on the output value of the angular velocity sensor force will be described later in detail, but since it is a known technique, detailed description thereof is omitted in this embodiment. The direction calculation unit 313 can be realized by, for example, a dedicated arithmetic circuit or a program. Hereinafter, the angular velocity calculated by the azimuth calculation unit 313 is Sa, the azimuth (absolute azimuth) calculated using this angular velocity Sa is Θ g, and the absolute azimuth Θ g is called “calculated absolute azimuth Θ g”. . The absolute azimuth Θg calculated by the azimuth calculation unit 313 is used for display on the display unit 303, notification in the guidance sound output unit 306, and the like.

[0064] The direction calculation unit 313 calculates, for example, the angular velocity Sa and the calculated absolute direction Θ g Calculation is performed every sampling period T interval. Specifically, for example, when calculating the absolute orientation Θg at the sampling time ηΤ, the value obtained by integrating the angular velocity Sa at the sampling time nT with the sampling period T is used as the absolute value at the sampling time (n−l) T. Add to bearing 0 g.

 n-1

 Note that the calculated absolute azimuth Θ g is not limited to one calculated every time the angular velocity Sa is calculated (that is, every 100 msec interval). For example, it may be calculated every sampling cycle T interval such as lsec. Specifically, for example, when calculating the absolute bearing Θ gn at the sampling time nT, the ten angular velocities Sa to Sa calculated every 100 msec intervals are used.

 n n-9 Integrate the added value in lsec. In this case, a ring buffer for storing 10 or more angular velocities Sa is provided.

 In addition, the correction processing unit 314 performs predetermined correction calculation processing on the correction coefficient based on the absolute azimuth Θ g calculated by the azimuth calculation unit 313. The predetermined adjustment (correction) to the correction factor is performed when the absolute bearing 0 'can be obtained. In this embodiment, since the absolute orientation Θ, is acquired by the position acquisition unit 312 using GPS or using the road shape orientation data, the GPS signal cannot be received at a place! In addition, the correction coefficient can be adjusted (corrected).

 Specifically, for example, the correction processing unit 314 compares the absolute azimuth Θ g calculated by the azimuth calculation unit 313 with the absolute azimuth Θ acquired by the position acquisition unit 312, and uses this comparison result. Based on this, the correction coefficient is adjusted (corrected) by increasing or decreasing the correction coefficient in such a direction that the calculated absolute azimuth Θg asymptotically approaches the acquired absolute azimuth Θ ′. For example, the correction factor may be increased or decreased by 0.2%, or 0.1% or 0.00% depending on the previous or previous adjustment amount. Try adjusting it up or down by about 05%.

Note that the sensor value acquisition unit 101, determination unit 102, coefficient acquisition unit 103, angular velocity calculation unit 104, azimuth calculation unit 105, azimuth acquisition unit 106, and correction unit 107 shown in FIG. For example, the ROM or RAM in the navigation control unit 301 shown in FIG. 3 is! /, When the program recorded in the recording medium 304 is executed by the CPU in the navigation control unit 301, or The function is realized by various sensors. Next, specific configurations of the orientation calculation unit 313 and the correction processing unit 314 in this embodiment of the present invention will be described. FIG. 4 is a functional block diagram showing a specific configuration of the azimuth calculation unit 313 and the correction processing unit 314 in the present embodiment of the present invention. Specifically, the various functions described above in the azimuth calculation unit 313 and the correction processing unit 314 are realized by, for example, each unit illustrated in FIG. The direction calculation unit 313 in this embodiment of the present invention includes a subtraction processing unit 401, a multiplication processing unit 402, a product-sum processing unit 403, a straight-ahead determination processing unit 404, a zero adjustment processing unit 405, and a direction calibration. Processing unit 406, comparison processing unit 407, left turn determination processing unit 408, right turn determination processing unit 409, left turn correction coefficient adjustment processing unit 410, right turn correction coefficient adjustment processing unit 411, and correction coefficient selection acquisition And a processing unit 412. In FIG. 4, reference numeral 420 denotes an AZD conversion circuit that performs AZD conversion of analog output values of the angular velocity sensor force.

 First, the subtraction processing unit 401 calculates the above-mentioned “output value of angular velocity sensor force” by subtracting the voltage value force zero point (offset) voltage value output from the angular velocity sensor. The digital value that has been AZD converted by the AZD conversion circuit 420 is input to the subtraction processing unit 401. The multiplication processing unit 402 calculates the angular velocity before correction by multiplying the output value from the angular velocity sensor by the gain value, and multiplies the angular velocity before correction by the correction coefficient corresponding to the angular velocity before correction and the bending direction. The current angular velocity (hereinafter simply referred to as “angular velocity”) Sa is calculated. The gain value is a value set based on the correspondence between the output value from the angular velocity sensor and the angular velocity.

 [0071] Also, the product-sum processing unit 403 accumulates (accumulates) the relative azimuth ΔΘg calculated based on the angular velocity Sa calculated by the multiplication processing unit 402, thereby calculating the absolute value calculated for the vehicle. Calculate the bearing Θg. The straight traveling determination processing unit 404 determines whether or not the vehicle is in a straight traveling state based on the angular velocity Sa calculated by the multiplication processing unit 402. Specifically, the straight-ahead determination processing unit 404 has a displacement amount of the angular velocity Sa calculated by the multiplication processing unit 402 for a predetermined period (for example, 10) when traveling at a certain speed (for example, 30. OkmZh) or more. It is determined that the vehicle is traveling straight ahead for less than a predetermined threshold for a second).

[0072] Further, the zero adjustment processing unit 405 is configured so that the vehicle is in a straight traveling state by the straight traveling determination processing unit 404. If it is determined, the zero (offset) voltage value is adjusted so as to approach the average value of the output values from the angular velocity sensor in the predetermined period. The azimuth calibration processing unit 406 removes the influence of the dynamic zero-point drift of the angular velocity sensor, and calculates the calculated absolute azimuth Θ g to the acquired absolute azimuth Θ 'according to the output value of the angular velocity sensor force. Replace.

Specifically, for example, when the vehicle is traveling straight at a vehicle speed V equal to or higher than a predetermined value, the calculated absolute azimuth Θ g is changed to the absolute azimuth Θ acquired by the position acquisition unit 312. Replace. More specifically, for example, when the absolute azimuth Θ ′ cannot be replaced, the calculated absolute azimuth Θg is replaced with the absolute azimuth Θ ′ obtained using the road shape azimuth data. The comparison processing unit 407 compares the calculated absolute azimuth Θg with the obtained absolute azimuth Θ.

 [0074] Further, if the left turn determination processing unit 408 is a negative value of the angular velocity force before correction calculated by the multiplication processing unit 402, the left turn determination processing unit 408 determines that the vehicle has made a left turn. The right turn determination processing unit 409 determines that the vehicle has turned to the right if the angular velocity force before correction calculated by the multiplication processing unit 402 is a positive value.

 [0075] Further, the left turn correction coefficient adjustment processing unit 410, when the left turn determination processing unit 408 determines that the vehicle has made a left turn, the left turn correction coefficients La, Lb, Lc, ..., Li, · Among them, perform a predetermined adjustment (correction) for any one of the correction coefficients used for calculating the angular velocity Sa in the multiplication processing unit 402. The right-turn correction coefficient adjustment processing unit 411 performs a right-turn determination process. Any of the correction factors Ra, Rb, Rc,...,! ¾,... For right turn used for calculating the angular velocity Sa in the multiplication processing unit 402 when the unit 409 determines that the vehicle has made a right turn. Performs a predetermined adjustment (correction) for one correction coefficient.Adjustment (correction) of the correction coefficient by the left-turn correction coefficient adjustment processing unit 410 and the right-turn correction coefficient adjustment processing unit 411 is performed to the currently set correction coefficient. In contrast, for example, 0.2% or This is done by increasing or decreasing by 0.1% or 0.05% according to the amount of adjustment, etc. Adjustment (correction) of the correction coefficient by the left turn correction coefficient adjustment processing unit 410 and the right turn correction coefficient adjustment processing unit 411 is, for example, This is done each time the calculated absolute orientation Θg is calculated.

[0076] Then, when the angular velocity before correction is negative, the correction coefficient selection / acquisition processing unit 412 selects the left turn correction coefficient La, Lb, Lc, ···, Li, ··· before correction. Depending on the angular velocity of One correction factor is selected. Further, the correction coefficient selection acquisition processing unit 412 corrects the right turn correction coefficients Ra, Rb, Rc, ... when the angular velocity before correction is positive! The correction coefficient selected by the correction coefficient selection acquisition processing unit 412 is used for calculation of the angular velocity Sa in the multiplication processing unit 402. Is done.

 [0077] Here, before explaining the contents of the processing of the navigation device of the present embodiment, FIG. 5 shows a general correspondence between the sensitivity change due to the sensitivity characteristic of the angular velocity sensor and the correction coefficient. Description will be given with reference to FIG. FIG. 5 to FIG. 8 are explanatory diagrams for explaining the sensitivity change caused by the sensitivity characteristics of the angular velocity sensor. Fig. 5 shows a state where the angular velocity sensor is mounted horizontally, and Fig. 6 shows a state where the angular velocity sensor is mounted at an inclination. In general, the sensitivity characteristics of an angular velocity sensor are affected by the angle with respect to the horizontal direction during installation, in addition to general characteristics such as aging.

 [0078] As shown in FIG. 5 and FIG. 6, when the ideal angular velocity in the straight traveling state is ω and the angular velocity calculated based on the output value of the angular velocity sensor force is ω 2, the horizontal direction is The angular velocity sensor mounted at an angle of j8 is lower in sensitivity by COS (| 8) times compared to the angular velocity sensor mounted horizontally. In order to offset the effect of such a decrease in the sensitivity of the angular velocity sensor, when the angular velocity sensor is attached to the vehicle at an angle of β from the horizontal, the correction factor G is multiplied by COS (| 8). Is set to a value that increases the sensitivity of the angular velocity sensor that has decreased to (1ZCOS (| 8)) times. Note that the slope | 8 in FIG. 6 is exaggerated. In FIGS. 5 to 8, ω θ is the angular velocity at the zero voltage.

 [0079] Specifically, the correction coefficient G when the angular velocity sensor is mounted horizontally with respect to the vehicle.

 = 1 (see Fig. 5), the correction factor G corresponding to the sensitivity of the angular velocity sensor when the angular velocity sensor is mounted with a tilt of | 8 from the horizontal to the vehicle is approximately "1 + β" By doing so (see Fig. 6), it is possible to cancel out the effects of the reduced sensitivity of the angular velocity sensor. This means that the difference in the sensitivity of the angular velocity sensor due to the difference in bending direction does not appear just because the angular velocity sensor is mounted at an angle.

[0080] Hereinafter, the case where the sensitivity of the angular velocity sensor varies depending on the bending direction will be described. To do. The sensitivity of the angular velocity sensor differs depending on the turning direction when the vehicle inclination α during a right turn differs from the vehicle inclination α ′ during a left turn. Specifically, the sensitivity change of the angle sensor when the vehicle inclination a during a right turn and the vehicle inclination OC 'during a left turn are different due to, for example, a difference in curvature radius or driver's habit. Think.

 Here, for the sake of explanation, for the sake of convenience, the correction coefficient selected by the correction coefficient selection acquisition processing unit 412 is G, and the left-turn correction coefficients La and Lb acquired by the left-turn correction coefficient adjustment processing unit 410 , Lc, ···, Li, ··· is Gr, right turn correction factor adjustment processing unit 411 acquires right turn correction factors Ra, Rb, Rc, ...! ¾, ... is described as Gr. Here, for simplification of description, one correction coefficient Gr, G1 is used for each bending direction. However, as described above, the correction coefficient in this embodiment is the vehicle bending direction. A plurality (La, Lb ゝ Lc, ···, Li, ··· and Ra, Rb, Rc, ···,! ¾,…;) are set for each angular velocity.

 FIG. 7 shows an output state from the angular velocity sensor when the angular velocity sensor is mounted in a state parallel to a horizontal vehicle. In FIG. 7, ω 2 ′ indicates the angular velocity calculated based on the output value from the angular velocity sensor when the vehicle turns left. Therefore, the angular velocity ω 2 in FIG. 7 indicates the angular velocity calculated based on the output value of the angular velocity sensor force when the vehicle turns right. In FIG. 7, the slopes a and α ′ are exaggerated. As can be seen from Fig. 7, the sensitivity drops to approximately COS a times when turning right with a slope a. For this reason, the right-turn correction coefficient Gr that offsets this decrease in sensitivity rises to approximately (1 + a). When turning left with a tilt of a ', the sensitivity drops to approximately COS a' times. Therefore, the left-turn correction coefficient G1 that offsets this decrease in sensitivity rises to approximately (1 + a '). As a result, the difference Δ G between the correction coefficient Gr and the correction coefficient G1 becomes —. However, although the slopes a and a are different, the difference is usually slight, except when the driver is very strong.

[0083] However, even if the angular velocity sensor is mounted horizontally on the vehicle, the vehicle itself may be temporarily depending on the state of boarding / mounting of a vehicle occupant or baggage, road conditions, etc. It may have a certain slope continuously for a period of time. In this case, it corresponds to the inclination of the vehicle As a result, the angular velocity sensor may also be inclined. If this is the case, as described above, the force that should be offset by the dynamic adjustment of the correction coefficient G, the change of the correction coefficient will change when the rolling of the vehicle is further taken into account in such a tilted state. It becomes obvious.

 FIG. 8 shows an output state from the angular velocity sensor when the angular velocity sensor is mounted in an inclined state with respect to the horizontal direction of the vehicle and the vehicle is bent. In FIG. 8, as in FIG. 7, both the inclinations α and α ′ are exaggerated. As can be seen from Fig. 8, if the vehicle and therefore the angular velocity sensor has a continuous inclination β, the sensitivity falls to COS (+) times when turning right with inclination a. The right-turn correction coefficient Gr that offsets this decrease in sensitivity rises to approximately (1 + j8 + α).

 [0085] On the other hand, the sensitivity falls only COS (α ') times when turning left with a slope α'. For this reason, the left-turn correction coefficient G1 that offsets this decrease in sensitivity increases to (1 + j8-α '). As a result, when there is a slope β, the effect of the rolling on the right turn () and the rolling on the left turn on the correction coefficient Gr, G1 is reversed, so the correction coefficient Gr and the correction coefficient G1 The difference AG is about + α ').

 [0086] That is, when the vehicle is tilted continuously due to the mounting situation or the like, considering the rolling when the vehicle bends in addition to the tilted state, these are combined and The influence of the sensitivity characteristics of the angular velocity sensor is different when turning left. Note that the influence of the sensitivity characteristics of angular velocity sensors also varies depending on the angular velocity. More specifically, the greater the angular velocity, the greater the impact.

 The navigation device of this embodiment performs zero adjustment when it is determined that the vehicle goes straight! /, And removes the influence of the dynamic zero drift of the angular velocity sensor. If it is determined that the vehicle is bent, the correction coefficient is adjusted (corrected) so that the calculated absolute azimuth Θ is asymptotic to the acquired absolute azimuth Θ ', and the sensitivity of the angular velocity sensor during bending is reduced. Offset Adjustment (correction) of the correction coefficient during turning is performed independently for each turning direction of the vehicle. The contents of the processing of the navigation device will be described below.

[0088] (Contents of processing of navigation device) FIG. 9 is a flow chart for explaining the contents of the processing of the navigation apparatus that is useful in this embodiment of the present invention. In FIG. 9, the processing at the sampling time nT will be described. In the flowchart of FIG. 9, first, the output value of the angular velocity sensor force is acquired (step S901). Specifically, the output value from the angular velocity sensor acquired in step S901 is obtained by using the AZD conversion circuit 420 after removing noise from the analog voltage value output from the angular velocity sensor using a single pass filter. The zero voltage (offset) voltage value gy is subtracted from the value obtained by averaging the digital voltage value gy converted.

 n 0 minus the value (gy—gy).

 n 0

 [0089] Next, the output value (gy—gy) from the angular velocity sensor acquired in step S901.

 n 0 is multiplied by the gain value G to calculate the uncorrected angular velocity G '(gy—gy) (step

 n 0

 S902), based on the calculated angular velocity G '(gy -gy)

 n 0

 (Step S903), and based on the judgment result and the angular velocity G '(gy -gy) before correction.

 n 0

 One correction coefficient Gk is acquired (step S904).

 n-l

 [0090] Subsequently, the angular velocity G ′ (gy—gy) before correction calculated in step S902 is

 n 0 By multiplying the correction coefficient Gk obtained in step S904, the angular velocity Sa = G

 n-l n k -G- (gy- gy) is calculated (step S905), and the calculated angular velocity Sa is used to calculate the sample n-l n 0 n

 The relative orientation ΔΘ g at the ring time nT is calculated (step S906). In step S906, the bent angle of the sampling time (n−l) T time point force is calculated.

 [0091] The calculation of the relative orientation ΔΘR in step S906 is performed at every sampling period T interval for calculating the calculated absolute orientation Θg. Specifically, for example, when the calculated absolute azimuth Θg is calculated every sampling period T = 100 msec, in step S906, the angular velocity Sa calculated in step S905 is integrated by the sampling period. Relative orientation Δ Θ g is calculated.

[0092] Then, using the relative azimuth ΔΘg calculated in step S906, the calculated absolute azimuth Θg is calculated (step S907), and the acquired absolute azimuth Θ 'is acquired (step S908). . In step S907, specifically, for example, when calculating the absolute orientation Θg calculated at the sampling time nT, the absolute orientation Θg calculated at the sampling time (n-1) T is Calculated relative Add the direction Δ 0 g _n .

[0093] After that, the absolute azimuth 0 g calculated in step S907 is compared with the absolute azimuth 0 'obtained in step S908 (step S909), and the calculated absolute azimuth 0 g according to the comparison result. = 0 g + Δ 0 g is corrected to be asymptotic to the obtained absolute orientation Θ 'n n-1 n

 Adjust (correct) the coefficient Gk (step S910).

 n-1

 [0094] In step S910, adjustment (correction) is performed on the correction coefficient Gk acquired in step S904 by n-1. The adjusted (corrected) correction coefficient Gk, together with the other correction coefficients, is used for the next calculation of the angular velocity Sa. In step S910, n + 1

 For specific processing when adjusting (correcting) the correction coefficient Gk!

 For this reason (for example, see JP-A-10-307032 and JP-A-2005-49355;), the description is omitted here. In addition, if it is determined in step S903 that the vehicle is moving straight in step S903, the correction coefficient Gk in step S904 is not determined n-1, and the initial value Gk = 1 is used as the correction coefficient. .

 0

 [0095] In the above embodiment, the bending determination in step S903 is the force that performs the bending determination based on the angular velocity G ′ (gy -gy) before correction calculated in step S902! 0

 However, the bending determination may be performed based on the positive / negative n 0 of the output value gy -gy of the angular velocity sensor force acquired in step 901. In this case, the calculation of the angular velocity in step S902 and the order of the step S903 bending determination may be interchanged, and the bending determination may be performed first.

Next, the correction coefficient table will be described. FIG. 10 is an explanatory diagram showing a correction coefficient table. The correction coefficient table 1000 is recorded in the ROM or RAM or the recording medium 304 in the navigation control unit 301 shown in FIG. In FIG. 10, the correction coefficient table 1000 includes an angular velocity range area 1001 that defines the range of the angular velocity Sa, an interval area 1002 that defines the interval of the angular velocity Sa, and correction coefficients La, Lb, A correction coefficient area 1003 for storing Lc, ···, Li, ··· and Ra, Rb, Rc, ···, Ri, ··· and a force are also formed. The correction coefficient area 1003 includes a left turn correction area 1004 for storing left turn correction coefficients La, Lb, Lc,..., Li,..., And a right turn correction coefficient Ra, R b, Rc,. ¾, The right turn area 1005 that memorizes ... and the force are also configured. Next, a specific example of the correction coefficient table will be described. FIG. 11 is an explanatory diagram showing a specific example of the correction coefficient table. The correction coefficient table 1100 shown in FIG. 11 includes an angular velocity range area 1101, an interval area 1102 that defines an interval of the angular velocity Sa, and correction factors La 補正 Lb ゝ Lc, ..., Li, ..., Ra, Rb , Rc,..., Ri,... In the correction coefficient table 1100 shown in FIG. 11, the interval between the lower limit value of the angular velocity range and the range of the angular velocity Sa is stored in the angular velocity range area 1101 in a state where the numerical values are preliminarily calculated.

 In FIG. 11, the interval of the range of the angular velocity Sa is set so as to decrease as the angular velocity increases, so that the value force defined in the interval area 1102 is a component force. According to the correction coefficient table 1100 shown in FIG. 11, since the interval of the angular velocity Sa range is defined as shown in the interval area 1102, by setting the lower limit value of the angular velocity range, the angular velocity range area 1101 Specific numerical values in the range of each angular velocity Sa can be defined. Here, as the lower limit value of the angular velocity range, for example, an angular velocity Sa that can be regarded as straight traveling at an angular velocity Sa less than the lower limit value is set. In the correction coefficient table 1100, a value corresponding to the sensitivity of the angular velocity sensor is set as the correction coefficient related to the angular velocity Sa greater than or equal to a predetermined value.

 [0099] As described above, according to the present embodiment, except when the vehicle is traveling straight ahead, it is always based on the angular velocity calculated using the correction coefficient corresponding to the bending direction of the vehicle and the angular velocity before correction. The calculated absolute azimuth is calculated. Conventionally, a force that is not corrected unless the angular velocity exceeds a certain value. According to the present embodiment, the angular velocity is not affected by the magnitude of the angular velocity, and even when the angular velocity is not straight, Correction is performed.

 [0100] As a result, the accumulated error of the calculated absolute azimuth decreases, and it takes time until the accumulated amount of accumulated error increases, so the calculated absolute azimuth depends on the acquired absolute azimuth. The frequency of calibration is reduced, and the calculation accuracy of the calculated vehicle direction can be improved.

[0101] Conventionally, the cumulative error increases as the bending frequency increases, and there is a concern that the accuracy of the calculated absolute azimuth decreases. However, according to the present example, the higher the bending frequency, the more the sensitivity is corrected. More will be done. Thereby, it is possible to improve the calculation accuracy of the absolute direction calculated using the angular velocity. By the way, with respect to the calculated absolute azimuth, the larger the calculated angular velocity, the greater the influence of an error due to the inclination with respect to the horizontal plane. On the other hand, since the correction coefficient in this embodiment is set for each angular velocity range set so that the interval becomes narrower as the angular velocity is larger, the calculated absolute azimuth can be calculated more accurately.

 [0103] Further, according to the present embodiment, the correction coefficient is corrected based on the calculated absolute azimuth and the acquired absolute azimuth. As described above, by correcting the correction coefficient by using the calculated absolute direction and the acquired absolute direction in combination, the calculation accuracy of the calculated absolute direction can be further improved.

 According to the present embodiment, when it is determined that the vehicle is traveling straight, zero adjustment is performed, and the influence of the dynamic zero drift of the angular velocity sensor is removed. As a result, in this embodiment, when the vehicle equipped with the angular velocity sensor is traveling in a horizontal state (see FIG. 6), such a vehicle is mounted on a passenger / luggage etc. Even when the vehicle is traveling at an incline (see Fig. 7), it is possible to cancel out the effects caused by the reduced sensitivity of the angular velocity sensor.

 Here, according to the present embodiment, for example, when the sensitivity of the angular velocity sensor at the time of right turn decreases by COS α times or COS (+ H) times, the right turn correction coefficient 1 ^, 1¾, 1 ^, ...! ¾, ··· is corrected to lZCOS a times or 1ZCOS (J8 + α) times. This makes it possible to accurately offset the decrease in sensitivity of the angular velocity sensor when turning right.

 Further, according to the present embodiment, for example, when the sensitivity power COS a, double or COS (| 8−α ′) times of the angular velocity sensor at the time of the left turn decreases, Correction coefficients La ゝ Lb ゝ Lc ゝ ···, Li, ··· are corrected to lZCOS α, times or lZCOS (j8 — α,) times. As a result, it is possible to accurately offset the decrease in sensitivity of the angular velocity sensor when turning left.

As described above, by correcting the appropriate correction coefficient according to the calculated angular velocity, the accuracy of the angular velocity calculated thereafter can be further improved. Along with this, it is possible to improve the accuracy of the absolute bearing calculated based on the angular velocity. In other words, according to this embodiment, the bending direction and the angular velocity are not affected by the magnitude of the angular velocity. It is possible to calculate a high-accuracy angular velocity even when a vehicle that is temporarily tilted is bent by calculating an angular velocity using this correction factor. it can.

 [0108] By the way, if the calculation of the angular velocity when a vehicle that is tilting continuously temporarily bends is calculated as the calculation of the angular angle when the turning axis is inclined, it is based only on the output value from the angular velocity sensor. In order to calculate the absolute azimuth calculated in this way, a plurality of angular velocity sensors for detecting the angular velocity relating to the roll angle and pitch angle of the vehicle are required. On the other hand, according to the present embodiment, the angular velocity is calculated by using a correction coefficient set in accordance with the angular velocity for each turning direction of the vehicle, so that a single angle can be rotated without using a plurality of angular velocity sensors. It is possible to calculate the angular velocity in consideration of the inclination of the shaft, and to calculate the absolute direction in which this angular velocity force is calculated.

 In the present embodiment, the case where the angular velocity sensor for detecting the angular velocity relating to the angle is used has been described, but the angular velocity sensor applicable in the embodiment of the present invention is not limited to this. For example, the present invention may be applied to sensitivity (gain) correction of an angular velocity sensor that detects an angular velocity related to a roll angle or a pitch angle of a vehicle.

 [0110] By calculating the angular velocity related to the pitch angle of the vehicle using the azimuth calculation method described in the present embodiment, the vertical turning angle in the front-rear direction of the vehicle can be acquired. Here, the vertical rotation angle before and after the vehicle is regarded as the inclination in the traveling direction of the vehicle, and by calculating the angular velocity related to the pitch angle of the vehicle, the degree of inclination regarding the traveling direction of the vehicle is accurately grasped. can do.

 Similarly, by calculating the angular velocity related to the roll angle of the vehicle using the azimuth calculating method described in the present embodiment, the vertical turning angles of the left and right sides of the vehicle can be acquired. Here, by grasping the turning angle in the vertical direction on the left and right sides of the vehicle as the inclination of the vehicle with respect to the road surface, by calculating the angular velocity related to the roll angle of the vehicle, it is possible to accurately grasp the degree of inclination in the left and right direction of the vehicle. Can do.

[0112] In this embodiment, the case of using a single-axis angular velocity sensor that detects the angular velocity related to a single angle has been described. However, the angular velocity sensor applicable in the embodiment of the present invention is not limited to this. It is not limited to. For example, there are vehicle corners and roll angles Alternatively, a two-axis angular velocity sensor that detects a single angle and a pitch angle may be used to calculate an angular velocity related to the vehicle's single angle and roll angle, or the single angle and pitch angle. Also

Alternatively, the angular velocity related to the vehicle angle, roll angle, and pitch angle may be calculated using a three-axis angular velocity sensor that detects the vehicle angle, roll angle, and pitch angle.

 The azimuth calculation method described in the present embodiment can be realized by executing a program prepared in advance on a computer such as a personal computer or a workstation. This program is recorded on a computer-readable recording medium such as a hard disk, a flexible disk, a CD-ROM, an MO, and a DVD, and is executed when the recording medium force is also read by the computer. The program may be a transmission medium that can be distributed through a network such as the Internet.

Claims

The scope of the claims

 [1] Sensor value acquisition means for acquiring the output value of the angular velocity sensor force,

 Determination means for determining the bending direction of the moving body based on the output value acquired by the sensor value acquisition means;

 Based on the determination result determined by the determination means and the output value, a plurality of correction coefficient forces respectively set according to the angular velocity for each bending direction of the moving body The correction coefficient according to the output value Coefficient acquisition means for acquiring

 Based on the output value, an angular velocity calculating means for calculating the angular velocity of the moving body according to the bending direction of the moving body using the correction coefficient acquired by the coefficient acquiring means;

 Azimuth calculating means for calculating the azimuth of the moving body based on the angular velocity calculated by the angular velocity calculating means;

 An azimuth calculating apparatus comprising:

 [2] The coefficient acquisition means includes

 2. The azimuth calculation apparatus according to claim 1, wherein a correction coefficient set for each angular velocity range set so that the interval becomes narrower as the angular velocity is larger is acquired.

[3] Orientation acquisition means for acquiring an orientation indicating a traveling direction of the moving body;

 Correction means for correcting the correction coefficient acquired by the coefficient acquisition means based on the azimuth calculated by the azimuth calculation means and the azimuth acquired by the azimuth acquisition means;

 The azimuth calculating apparatus according to claim 1, further comprising:

[4] A sensor value acquisition process for acquiring the output value of the angular velocity sensor force,

 A determination step of determining the bending direction of the moving body based on the output value acquired by the sensor value acquisition step;

 Based on the determination result determined by the determination step and the output value, a plurality of correction coefficient forces respectively set according to the angular velocity for each bending direction of the moving body The correction coefficient according to the output value A coefficient acquisition step of acquiring

Based on the output value, the angular velocity of the moving body corresponding to the bending direction of the moving body is calculated. An angular velocity calculation step of calculating using the correction coefficient acquired by the coefficient acquisition step;

 An azimuth calculating step for calculating an azimuth of the mobile body based on the angular velocity calculated by the angular velocity calculating step;

 The direction calculation method characterized by including.

[5] An azimuth calculation program that causes a computer to execute the azimuth calculation method according to claim 4.

 [6] A recording medium in which the azimuth calculation program according to claim 5 is recorded so as to be readable by a computer.