JP6594546B2 - Angle measuring device - Google Patents

Description

  The present invention relates to an angle measurement device that measures an angle of a moving body.

  There is a growing demand for vehicle state (angle, attitude) detection such as autonomous driving and advanced driving support systems (ADAS), but the application of inertial sensors as measuring means is expanding. As a method for measuring the angle of the moving body, there are a measurement method using an angular velocity sensor and a measurement method using an acceleration sensor, and there are factors including measurement errors in each measurement principle.

  For example, in the method of calculating the tilt angle “θ” using an angular velocity sensor, the angular velocity output (deg / s) is integrated over time to calculate the angle, but the sensor output is integrated over time. There is a problem that the angle error increases due to accumulation of other error factors.

  Also, in the case of calculating the angle “θ” using an acceleration sensor, Arc tan θ is used. However, gravity acceleration and inertial force are superimposed on each other. There is a risk. Although it is possible to calculate the tilt angle using the gravitational acceleration, the angle change on the horizontal plane (XY axis) perpendicular to the gravitational acceleration (Yaw angle), that is, the angle change on the horizontal plane perpendicular to the gravitational acceleration. Is difficult to calculate.

  Patent Document 1 discloses a technique in which zero point calibration of an angular velocity sensor provided in a moving body including a vehicle is performed by determining whether the moving body is stationary.

JP 2003-002141 A

  In the technique of Patent Document 1, the zero point of the angular velocity sensor or the acceleration sensor is calibrated in a stationary state. Therefore, in continuous motion (for example, highway driving of a vehicle), the zero point cannot be calibrated for a long time, and if the angle is calculated by integrating the angular velocity sensor, the error of time integration may increase.

  The present invention has been made in view of the above points, and an object of the present invention is to provide an angle measuring device capable of measuring an accurate deflection angle of a moving body in a continuous motion state. is there.

  An angle measuring device of the present invention that solves the above-mentioned problem is an angle measuring device that measures a deflection angle in a yaw direction of a moving body in motion, and when the moving body receives a reference value set signal in a state of motion motion And a deflection angle calculating means for calculating a deflection angle in the yaw direction.

  According to the present invention, an accurate deflection angle of a moving body during exercise can be measured. Further features related to the present invention will become apparent from the description of the present specification and the accompanying drawings. Further, problems, configurations, and effects other than those described above will be clarified by the following description of embodiments.

The figure which shows an example of the inertial sensor mounted in the moving body and the moving body. The figure explaining the structure of an inertial sensor. The block diagram of the input / output and signal processing of an inertial sensor. The flowchart explaining an angle measurement method. The timing chart which shows the change of an acceleration sensor output and an angular velocity sensor output. The figure explaining an example of the conditions from which a reference value set signal is output. The figure explaining an example of the conditions from which a reference value set signal is output.

Next, examples of the present invention will be described.
FIG. 1 is a diagram illustrating an example of a moving body and an inertial sensor mounted on the moving body.
The angle measurement device measures the deflection angle in the yaw direction of a running vehicle that is a moving body. The left and right direction of the vehicle arranged on a horizontal virtual plane is the X axis, the front and rear direction is the Y axis, and the vertical direction The direction is the Z axis, and the amount of change in the yaw angle around the Z axis is measured as the deflection angle while the vehicle is traveling.

  The angle measuring device is configured in the inertial sensor 100. As shown in FIG. 1A, the inertial sensor 100 is installed at a position close to the center of gravity of the moving body (vehicle) 10, and when the inertial force (acceleration, angular velocity) is applied, the behavior of the moving body 10 is measured. It is installed so that the relationship between the angle (posture) of the moving body 10 and the X-axis, Y-axis, and Z-axis of the vehicle can be understood. As shown in FIG. 1 (b), the moving body 10 has its left-right direction (vehicle width direction) as the X axis, the front-rear direction as the Y-axis, and the vertical direction as the Z-axis. , Roll around the Y axis, and yaw around the Z axis. The X axis, the Y axis, and the Z axis are orthogonal coordinates that form an angle of 90 degrees.

  Here, the installation of the inertial sensor 100 on the moving body 10 does not necessarily require the X axis, the Y axis, and the Z axis of the inertial sensor 100 to be horizontal or vertical with respect to the axis to which the gravitational acceleration is applied. It may be installed in an angled state. In this case, the angle of the sensor in a state where inertia force does not work (for example, a constant velocity motion state) is set to the installation angle of the moving body 10. However, in the moving body 10 installed at an angle, the X axis, the Y axis, and the Z axis are orthogonal to each other except for error factors such as misalignment of sensor elements.

FIG. 2 is a diagram illustrating a configuration of the inertial sensor.
The inertial sensor 100 houses a sensor element 103 and a circuit element 102 that performs sensor output signal processing in an exterior case 101. The exterior case 101 is provided with an attachment hole 104 for attachment to the moving body 10. The sensor element 103 includes an acceleration sensor (G sensor) 132 and an angular velocity sensor (gyro sensor) 131 as sensor means for measuring the acceleration and angular velocity of the moving body 10.

  The acceleration sensor 132 and the angular velocity sensor 131 measure triaxial acceleration and triaxial angular velocity. The sensor element 103 may not be included in one package as shown in FIG. 2, and may be a combination of one or more acceleration sensors and one or more angular velocity sensors. Further, a combination sensor in which one or more acceleration sensors and one or more angular velocity sensors are combined may be used. The angular velocity sensor having one or more axes and the acceleration sensor having one or more axes may be integrated into a single package or a plurality of single sensors. As a matter of course, the angular velocity sensor and the acceleration sensor may be integrated into one package.

  FIG. 3 is a block diagram of inertial sensor input / output and signal processing, and shows the signal transmission configuration, circuit block, and angle calculation (calculation) circuit configuration of the inertial sensor 100.

  The sensor element 103 includes a triaxial angular velocity sensor 131 and a triaxial acceleration sensor 132. The sensor element 103 passes through an A / D converter 134 that processes sensor outputs from the sensors 131 and 132, and then a DSP (digital signal processor). Or a signal processing arithmetic circuit 135 such as a microcomputer.

  The triaxial acceleration sensor 132 is an X axis G sensor that detects an acceleration Gx in the X axis direction, a Y axis G sensor that detects an acceleration Gy in the Y axis direction, and a Z that detects an acceleration Gz in the Z axis direction. Axis G sensor is provided. The triaxial angular velocity sensor 131 includes a yaw sensor (Yaw sensor) that measures the angular velocity in the yaw direction, a roll sensor (Roll sensor) that measures the angular velocity in the roll direction, and a pitch sensor (Pitch) that measures the angular velocity in the pitch direction. Sensor).

  A signal processing arithmetic circuit 135 such as a DSP or a microcomputer calculates and corrects the outputs from the angular velocity sensor 131 and the acceleration sensor 132 to a predetermined output, and uses the output of the temperature sensor 133 to correct the sensor output and perform self-diagnosis. Perform defect detection. These data are sent to the circuit element 102 such as a microcomputer via the communication interface 136, and the circuit element 102 performs an angle calculation calculation process (calculation processing means). The circuit element 102 sends sensor output, calculation result, diagnosis result, and other output related to the sensor to the controller 110 for control.

  The circuit element 102 obtains the output of the triaxial angular velocity sensor 131 and the output of the triaxial acceleration sensor 132 from the sensor element 103, and from these outputs, the inertial force in each direction acting on the moving body 10 at a certain point in time is obtained. The posture angle of the moving body 10 is calculated. For example, the circuit element 102 integrates the angular velocity in the yaw direction, which is the sensor output of the yaw sensor, and calculates the angle in the yaw direction from the integrated value. Note that the processing unit for calculating or calculating the inertial force and the posture angle is an arithmetic element such as a DSP or a microcomputer in the sensor element 103, the circuit element 102, or the control controller 110. The angle can be calculated. The circuit element 102 is mounted in the sensor element 103 or the control controller 110. When the circuit element 102 is mounted on the control controller 110, it is effective for shortening the processing time such as shortening the communication time to the sensor element 103.

  The controller 110 for control outputs a reference value set signal to the circuit element 102 based on preset conditions. The reference value set signal is, for example, when it is determined that the accurate yaw angle of the moving body 10 needs to be measured, and when the motion state of the moving body 10 is in a state in which the accurate yaw angle can be measured by the sensor element 103. (Reference value set signal output means).

  The controller 110 for control determines that it is necessary to measure the yaw angle from the wheel speed sensor, GPS, navigation system, camera and other external sensors in response to the presence of the moving body 10 and a certain position. To do. In addition, if the inertial force does not act on the moving body 10, the error can be minimized even if the angular velocity, which is the sensor output of the angular velocity sensor 131, is integrated, so it is determined that the yaw angle can be measured accurately. To do. The output of the reference value set signal can also be performed according to the driver's intention. This is also effective when traveling on narrow roads, curves, roads with many hills, or when the outside world cannot be recognized due to bad weather and it is desired to travel accurately in the lane.

FIG. 4 is a flowchart for explaining the angle measurement method.
First, the sensor output of the sensor element 103 is input to the circuit element 102 (S120). Then, in the circuit element 102, it is determined whether or not the input of the reference value set signal is received from the control controller 110 (S121). When the reference value set signal output from the control controller 110 is detected (S121) And YES), a process of calculating the deflection angle of the moving body 10 is performed (S122).

  When the circuit element 102 detects the reference value set signal output from the control controller 110 (signal detection means), the circuit element 102 starts time integration of the sensor output of the yaw sensor from the time when the input of the reference value set signal is received, and the yaw angle And the yaw angle is used as the deflection angle of the moving body 10 (a deflection angle calculation means). As a result, the yaw angle at the time when the input of the reference value set signal is received as a reference, and the deflection angle that is the difference from the yaw angle that has changed due to the subsequent movement of the moving body 10 can be obtained. In addition, although it is description about a yaw angle here, a roll angle and a pitch angle can be similarly integrated.

  The control controller 110 outputs a reference value set signal when it is necessary to measure an accurate yaw angle of the moving body 10. Whether or not the accurate yaw angle of the moving body 10 needs to be measured depends on the captured image obtained by capturing the external environment with the camera mounted on the moving body 10, the vehicle position information acquired from the navigation system and GPS, The determination is based on at least one of the own vehicle behavior information acquired from the wheel speed sensor or the steering sensor.

  For example, if GPS information does not reach (underpass, tunnel, parking lot in the building, multistory parking lot, etc.), there are many curves, a large radius angle is predicted, and the position information of the navigation system cannot be confirmed accurately, Alternatively, when the moving body deviates from the normal travel by the information of the wheel speed sensor and the steering sensor and the information of the skid prevention device, in the conventional yaw angle calculation method based on the zero point reset at the time of stopping, An increase in error is expected. When the error increases, the system cannot recognize the traveling direction of the host vehicle, which may hinder autonomous driving and traveling of the advanced driving support system (ADAS).

  In the present embodiment, in the control controller 110, whether or not it is necessary to accurately grasp the direction in which the moving body 10 subsequently moves based on at least one of the captured image, the own vehicle position information, and the own vehicle behavior information. That is, it is determined whether or not it is necessary to measure the accurate yaw angle of the moving body 10, and when it is determined that it is necessary, processing for outputting a reference value set signal is performed. Therefore, conventionally, even in a situation where an increase in error is expected, the deflection angle in the yaw direction can be accurately measured.

  The reference value set signal is output when the sensor element 103 is in a motion state in which an accurate yaw angle can be measured, that is, when the inertial force is not applied to the moving body 10 (for example, a constant speed motion state). Also good. Whether or not the motion state of the moving body 10 is a constant velocity motion state is determined based on the following condition (1) and the following condition (2).

Condition (1): The angular velocity in the yaw direction, the angular velocity in the roll direction, and the angular velocity in the pitch direction measured by the angular velocity sensor 131 are values in a predetermined range including zero.
Condition (2): the acceleration _{G Y} and vertical acceleration _{G Z} of the acceleration _{G X} and the left-right direction in the longitudinal direction measured by the acceleration sensor 132 is ^{_{√ (G X 2 + G Y}} 2 + G Z 2) = A (A is Satisfy a relationship of a predetermined range including 1).

The condition (1) is satisfied when the output (angular velocity) of each axis (yaw, roll, pitch) of the angular velocity sensor 131 is “0”, and the condition (2) is satisfied for each axis ( This is true when the value (acceleration) of the X-axis, Y-axis, and Z-axis is √ (G _X ² + G _Y ² + G _Z ² ) = “1” (g) (= 9.8 m / s ² ). When at least one of the condition (1) and the condition (2) is satisfied, the inertial force acting on the moving body 10 is “0”, that is, the moving state of the moving body 10 is a constant velocity movement state. Judge that there is.

  When condition (1) and condition (2) are satisfied, the inertial force input to the moving body 10 is “0”, so the calculated yaw angle is accurate to the absolute angle with respect to the traveling direction of the vehicle. This makes it possible to perform a setting operation in which the yaw angle is set to an accurate value during exercise (running). That is, if either condition (1) or condition (2) is satisfied, this is a state of “inertial force 0” where the inertial force is not applied to the moving body 10 (constant velocity motion state), and so on. When the sensor output of the angular velocity sensor 132 is set to the reference value in the fast motion state, the angle (yaw angle, roll angle, pitch angle) from which the angular velocity can be integrated can minimize integration error and accuracy. It is possible to obtain a high angle.

  Note that each output “0” of the angular velocity sensor 131 in the condition (1) or “1” in the calculation formula in the condition (2) includes noise and other error factors of the sensor, and should be set within a certain range. Is possible. For example, since the error including noise and drift of the angular velocity sensor 131 is generally considered to be within 1 deg / s, the settable output range of the angular velocity sensor 131 can be ± 1 deg / s. That is, it is determined that the condition (1) is satisfied when the outputs of the respective axes (yaw, roll, pitch) of the angular velocity sensor 131 are within the range of 0 ± 1 deg / s.

  Preferably, the signal-to-noise ratio (SNR) can be reduced to ½ by increasing the detection sensitivity of the angular velocity sensor 131 by a factor of two. Including these, by suppressing the accuracy of the whole sensor to ± 0.5 deg / s or less, the settable output range of the angular velocity sensor 131 is ± 0.5 deg / s, and the posture of the moving body 10 is made more accurate. Can do.

  Similarly, in the acceleration sensor 132, the error including noise and drift is generally 20 mg (19.6 × 10^-2m / s²Therefore, the settable range of the acceleration sensor 132 can be ± 20 mg. That is, a calculation formula √ (G using values of each axis of the acceleration sensor 132_X ²+ G_Y ²+ G_Z ²) Is in the range of 1 g ± 20 mg, it is determined that the condition (2) is satisfied. Preferably, the signal-to-noise ratio (SNR) can be reduced to ½ by increasing the detection sensitivity of the acceleration sensor 132 by a factor of two. Including these, by suppressing the accuracy of the entire sensor to ± 10 mg or less, the set range can be set to ± 10 mg, and the deflection angle of the moving body 10 in the yaw direction can be further increased.

  Whether or not the moving body 10 is in a constant speed motion state can be determined when the time during which at least one of the above condition (1) and the following condition (2) is satisfied is a certain time or more. . This is because there is a possibility that the condition (1) or the condition (2) may be instantaneously satisfied by noise or the like, and reliability may not be ensured. Note that the data sampling cycle is preferably a CAN communication update cycle of 10 ms or less.

  Whether or not the moving body 10 is in a constant velocity motion state may be determined using both the acceleration detected by the acceleration sensor 132 and the angular velocity detected by the angular velocity sensor 131. Even if the inertial sensor 100 cannot measure the triaxial angular velocity and the triaxial acceleration, or has no measuring element, the output of the angular velocity sensor is “0”, and the output of the X axis and Y axis acceleration sensors is “0”. Alternatively, the case where the output of the Z-axis acceleration sensor is “1” may be combined to determine whether or not the inertia force is “0” (whether or not it is in a constant velocity motion state). The inertial sensor 100 includes at least one of an acceleration sensor that measures acceleration in one or more axial directions and an angular velocity sensor that measures angular velocity around one or more axes, and measures at least one of the acceleration sensor and the angle sensor. Based on the measured value, it can be determined whether or not the motion state of the moving body 10 is a constant velocity motion state.

  There are cases in which a skid prevention device and a rollover detection control system are standard equipment in an automobile. Inertia sensor for skid prevention device measures angular velocity of 1 axis (yaw) and acceleration of 2 axes (measurement of longitudinal and lateral acceleration) or 3 axis acceleration (acceleration of longitudinal, lateral and vertical directions). . The rollover detection inertial sensor measures one-axis (roll) angular velocity and one-axis acceleration (vertical acceleration measurement) or two-axis acceleration (vertical and horizontal acceleration).

  By using the output signals of the inertial sensor for the side slip prevention device and the inertial sensor for rollover detection, the inertial force (yaw, roll, front / rear, left / right, vertical acceleration) can be measured. Therefore, in combination with the case where the output of the angular velocity sensor is “0”, the output of the X-axis and Y-axis acceleration sensors is “0”, or the output of the Z-axis acceleration sensor is “1” in the circuit element 102, It may be determined that the inertia force is “0”, that is, a constant velocity motion state. The angle and attitude calculations using the above-mentioned inertial sensors for skid prevention devices and rollover detection sensors are performed by a control controller, a microcomputer that can perform calculation processing, and a DSP, even if not in the circuit element 102. May be.

FIG. 5 is a timing chart showing changes in the acceleration sensor output and the angular velocity sensor output.
The sensor output (1) of the angular velocity sensor of each axis, the sensor output (2) of the acceleration sensor of each axis, and the calculation result (3) of the acceleration sensor output are within predetermined ranges (shown by broken lines in FIG. 5). It is based on the assumption that the controller 110 for control assumes that the inertial force does not work (for example, constant velocity motion state) and an accurate yaw angle can be measured. A value set signal is output. The reference value set signal is obtained when the sensor output (1) of the angular velocity sensor of each axis, the sensor output (2) of the acceleration sensor of each axis, and the calculation result (3) of the acceleration sensor output are continuously received multiple times. It is desirable to output to This is based on the condition that it has entered multiple times in succession, and even though there is inertial force, it accidentally enters the predetermined range, and the yaw obtained from the sensor output of the angular velocity sensor 131 at that time. This is to avoid the corners being set as correct values.

6 and 7 are diagrams illustrating an example of the timing at which the reference value set signal is output. FIG. 6 shows a case where a reference value set signal is output based on a captured image, own vehicle position information, own vehicle behavior information, and the like.
As shown in FIG. 6, the angle measuring device includes a captured image obtained by capturing an external environment with a camera mounted on the moving body 10 while the moving body (own vehicle) 10 is traveling on the road 20, a navigation system, and a GPS. Based on at least one of the acquired own vehicle position information and own vehicle behavior information acquired from the wheel speed sensor or the steering sensor, the road condition ahead is grasped. Then, the reference point 21 is set in front of the curve of the road 20, and a reference value set signal is output when the moving body 10 passes the reference point 21, and then the angular velocity output from the yaw sensor of the angular velocity sensor 131 is integrated. Start. Therefore, the yaw direction deflection angle of the moving body 10 on the curve can be measured with high accuracy, and the moving body 10 can perform high-precision self-sustained traveling and follow-up traveling.

FIG. 7 shows a case where the reference value set signal is output by setting the time of the control controller or the like.
As shown in FIG. 7, the angle measuring device includes a captured image obtained by capturing an external environment with a camera mounted on the moving body 10 while the moving body (own vehicle) 10 is traveling on the road 20, a navigation system, and a GPS. Based on at least one of the acquired own vehicle position information and own vehicle behavior information acquired from the wheel speed sensor or the steering sensor, the road condition ahead is grasped. Then, the reference point 22 is set at a certain time interval (for example, 50 ms or less that is less than the image processing time of the camera) so that the reference point 22 is continuously arranged on the road 20 with a predetermined interval. When the moving body 10 passes the reference point 22, a reference value set signal is output, and thereafter integration of the angular velocity output from the yaw sensor of the angular velocity sensor 131 is started. Therefore, it is possible to accurately measure the deflection angle of the yaw direction billion of the moving body 10 traveling on the road 20, and the moving body 10 can perform high-precision self-sustained traveling and follow-up traveling. It is also effective for complementing within the processing time interval of a camera or the like. Here, as a matter of course, this method can be applied to a stationary moving body.

  Further, the end of calculation (the time for calculating the angle by integrating the signals of the angular velocity sensor) is to output an end signal to the circuit element 102 based on information from the camera, the navigation system, and the like. This is effective in reducing the load on the circuit element 102 when the amount of data is large, and is effective in preventing the calculation time from increasing and the angular error from increasing (accumulated error due to integration in the angular velocity sensor). Because.

Completion of calculation has a function to cancel the calculation process in the angle calculation unit 102 because there is a case where a rough road, a slipping running state, and a road surface have large temporal fluctuations and the inertial force cannot be measured accurately. It is also possible. The means for detecting this state is to output a calculation stop command from the control controller 110 to the circuit element 102 based on sensor information such as an acceleration sensor and an angular velocity sensor as well as a wheel speed sensor and a steering sensor. Alternatively, based on the information of the inertial sensor 100, the calculation processing unit in the inertial sensor 100 may make a determination and end processing may be performed. From the above, by calculating the output of the inertial sensor 100, there is an effect that the angle of the moving body 10 can be accurately measured even during exercise.
According to the angle measuring apparatus of the present embodiment, during the movement of the moving body 10, the position and state information of the moving body 10 is confirmed by GPS, a camera, a navigation system, etc. A signal that sets (starts integration) the sensor signal from a certain point in time is output, and the sensor circuit of the angular velocity sensor (yaw sensor) is integrated by the processing circuit based on that signal, so that the moving body 10 from the certain point in time is integrated. Can be accurately measured.

  Although the embodiments of the present invention have been described in detail above, the present invention is not limited to the above-described embodiments, and various designs can be made without departing from the spirit of the present invention described in the claims. It can be changed. For example, the above-described embodiment has been described in detail for easy understanding of the present invention, and is not necessarily limited to one having all the configurations described. Further, a part of the configuration of an embodiment can be replaced with the configuration of another embodiment, and the configuration of another embodiment can be added to the configuration of an embodiment. Furthermore, it is possible to add, delete, and replace other configurations for a part of the configuration of each embodiment.

10: moving body, 100: inertial sensor, 101: exterior case, 102: circuit element, 103: sensor element, 104: mounting hole, 110: control controller,

Claims (5)

An angle measurement device that measures the yaw angle of a moving body during exercise,
A yaw sensor for detecting an angular velocity in a yaw direction of the moving body;
An imaging device that is mounted on the moving body and images an external environment;
A reference value set signal output means for outputting a reference value set signal during exercise of the moving body based on a preset condition;
A deflection angle calculating means for calculating the deflection angle in the yaw direction of the moving body to start integration of the sensor output of the yaw sensor from the time of receiving the reference value set signal,
I have a,
The reference value set signal output means detects a curve ahead of the moving body based on a captured image captured by the imaging device, and a constant velocity motion in which inertial force does not act on the moving body before the detected curve. An angle measuring device that outputs the reference value set signal in a state . The angle measuring device according to claim 1 , wherein the deflection angle calculation unit is set in a sensor or in a control controller. Equipped with angular velocity sensor and acceleration sensor,
The angle measurement device according to claim 1 , wherein the reference value set signal is output when at least one of the following condition (1) and the following condition (2) is satisfied during the movement of the moving body. .
Condition (1): The angular velocity in the yaw direction, the angular velocity in the roll direction, and the angular velocity in the pitch direction measured by the angular velocity sensor are values in a predetermined range including 0, respectively.
Condition (2): The longitudinal acceleration G _{X, the} lateral acceleration G _Y and the vertical acceleration G _Z measured by the acceleration sensor are √ (G _X ² + G _Y ² + G _Z ² ) = A (A is Satisfy a relationship of a predetermined range including 1). The angle measuring device according to claim 1 , further comprising a sensor element having a multi-axis angular velocity sensor and a multi-axis acceleration sensor. The integration of the signal of the angular velocity sensor, the time for calculating the angle, based on information of the imaging device or the navigation system, the angle measuring device according to claim 1, characterized in that the ends.

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