JP2661014B2 - Auto cruise equipment for vehicles - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an auto cruise device for a vehicle that can travel while maintaining a proper inter-vehicle distance with a preceding vehicle. 2. Description of the Related Art In general, an auto cruise system for a vehicle detects an inter-vehicle distance to a preceding vehicle by a radar device, obtains an own vehicle speed by a vehicle speed sensor, calculates an appropriate inter-vehicle distance from these values, and The operation of the brake and the accelerator is controlled so as to achieve a suitable inter-vehicle distance, which is effective for eliminating complicated driving operations on traffic congestion roads, for example. (See Japanese Patent Application Laid-Open No. 60-91500) As a radar device in the above-mentioned auto cruise device, for example, as described in Japanese Patent Application Laid-Open No. 59-92372, a laser diode is used. It has been proposed to transmit a laser beam toward a vehicle ahead and receive the reflected light to obtain an appropriate inter-vehicle distance based on a propagation delay time from emission of the laser beam to reception of the laser beam. [Problems to be Solved by the Invention] However, in such a vehicle auto-cruise system provided with such a conventional radar device, a so-called tracking mode in which the traveling mode of the own vehicle outputs laser light to a preceding vehicle. Even if the vehicle is in the middle or in the stop mode in which the vehicle is almost stopped, a relatively large power laser beam capable of detecting at least the preceding vehicle within the tracking limit distance (for example, 30 m) is always constant regardless of the traveling mode. For example, even when the host vehicle is stopped during an auto-cruise operation on a traffic jam, a high-output laser beam is output, and the radar device becomes unnecessary. Operation is performed, resulting in unnecessary consumption of the battery. On the other hand, Japanese Utility Model Application Laid-Open No. 58-189978 discloses a technique for changing the intensity of laser light in accordance with the speed of the host vehicle. This technology increases the laser beam intensity because it can be estimated that the inter-vehicle distance to the preceding vehicle is large at high speeds, so that the inter-vehicle distance can be accurately measured even for a distant vehicle. When traveling in a city where the distance of the vehicle is short, the speed of the own vehicle can be estimated to decrease, so that the laser beam intensity is reduced. However, in practice, it is naturally conceivable that the distance from the vehicle in front (inter-vehicle distance) is large even when the vehicle speed is low, and even in such a case, the laser beam intensity is set low in the technique described in the above-mentioned publication. Therefore, there is a problem that the measurement of the inter-vehicle distance cannot be performed accurately. Therefore, the present invention provides an auto cruise device for a vehicle which can accurately measure the inter-vehicle distance with a preceding vehicle without performing unnecessary operation of the radar means even when the speed of the own vehicle is low. With the goal. [Means for Solving the Problems] In order to achieve this object, the present invention provides a radar unit 201 for detecting an inter-vehicle distance to a preceding vehicle, a speed detecting unit 202 for detecting a speed of a host vehicle, and the inter-vehicle distance. And an arithmetic processing means 204 for outputting a speed command to a speed increasing / decreasing mechanism 203 so as to maintain an appropriate inter-vehicle distance based on the own vehicle speed. Determining means 205 for determining whether the vehicle is in a substantially stopped state or a normal running state based on
When the determination unit 205 determines that the vehicle is in a substantially stopped state and the inter-vehicle distance detected by the radar unit 201 is small, the control unit 2 reduces the output of the radar unit 201 to a low output.
06 is provided. Hereinafter, an embodiment of the present invention will be described in detail with reference to the drawings. A radar device (radar means) 3 having the laser diode 1 shown in FIG. 1 has a D / A converter which outputs an appropriate driving voltage for driving the laser diode 1 from the microcomputer 5 (arithmetic processing means). The D / A converter 7 is connected to the anode side of the laser diode 1 via the voltage follower 9 and the collector resistor 11, and the cathode side of the laser diode 1 is connected to a transistor 13 for driving the laser diode. Connected to the collector side. The emitter side of the transistor 13 is grounded, the base side is connected to a base resistor 15 and a counter 17, and the counter
Reference numeral 17 is connected to the microcomputer 5. these
The circuit section from the D / A converter 7 to the base resistor 15 serves as the transmission section of the radar device 3. The counter 17 counts the delay time (proportional to the inter-vehicle distance to the preceding vehicle) from when the laser beam is transmitted to when it is received, and sends this count value to the microcomputer 5. As a result, the computer 5 performs a distance measurement operation for the vehicle. On the other hand, the receiver of the radar device 3 includes a photodiode 19 having a cathode grounded, a resistor 21 connected to the anode of the photodiode 19, and an amplifier 2 connected to the resistor 21.
3, furthermore, the amplifier 23 is connected to the input side and the output side is the counter 1
It comprises a comparator 25 connected to 7. Radar device 3 including transmission unit and reception unit described above
Can output a low-output laser power Pl in a stop mode in which the host vehicle is in a substantially stopped state and a high-output laser power Ph in a tracking mode in a normal running state. The two types of laser powers Pl and Ph are selected as follows. That is, as shown in FIG. 2, generally, P = k · L ₄ [between the inter-vehicle distance L [m] to the vehicle in front and the laser power P [w] required to detect the vehicle in front. However, the relationship of k: constant holds. Although the light reflection intensity of the laser beam varies depending on the type of the vehicle ahead, here, the laser power at a distance of 50 [m] for the vehicle ahead with the standard light reflection intensity
Assume that Ph [w] is required. At this time, for example, when the inter-vehicle distance is 5 [m] or less in the stop mode, the laser power
Pl can be selected as small as 10 ^-4 Ph [w], and its laser power Pl is set to an intensity that does not hinder human eyes, for example, IEC (I
The intensity may be selected to be equal to or less than the MPE (maximum allowable exposure) value of the radiation safety standard (nterna-tional Electrotechnical Commission). In order to output the two kinds of laser powers Pl and Ph selected in this way, a digital voltage value corresponding to each power is given to the D / A converter 7 and a current corresponding to each power is supplied to the laser diode 1. You only need to supply them. In this case, the output values of the laser power are two types, Pl and Ph, but the present invention is not limited to this. For example, P = P in FIG.
It may be given continuously laser power P as a function of k · L ₄ against inter-vehicle distance L, and of course to provide a voltage value corresponding to the laser power P to the D / A converter 7 also in this case. For example, the microcomputer 5 is operated by a set switch 27 for operating the radar device 3 in a traffic congested road to start a tracking operation with respect to a preceding vehicle, an operation of a brake 29 by a driver, and a shift operation (not shown). The signals of the brake switch 31 and the shift switch 33 for canceling the tracking operation are input. The vehicle speed sensor (speed detection means) 35 outputs a voltage proportional to the frequency of the vehicle speed pulse of the host vehicle, and the throttle opening sensor 37 outputs a voltage value proportional to the throttle opening of the host vehicle. Each of these voltage values is input to the A / D converter 39, where the analog value is converted to a digital value and then input to the microcomputer 5. The microcomputer 5 outputs an operation signal to the throttle operation actuator 41 and the brake operation actuator 43. The two actuators 41, 43 constitute a speed increasing / decreasing mechanism. Throttle actuated actuator
Reference numeral 41 denotes a pneumatic or motor type, which receives a throttle opening signal from the microcomputer 5 and connects a throttle 47 in a throttle chamber 45 to a throttle wire.
Open and close via 49. The other end of the throttle wire 49 is connected to an accelerator pedal 50. On the other hand, the brake operation actuator 43 is of a hydraulic type or a pneumatic type, and performs brake control in response to a brake operation signal from the microcomputer 5. The microcomputer 5 is further connected to a monitor 51, and the monitor 51 displays that the apparatus is performing a tracking operation with respect to a vehicle ahead. Next, the operation of the microcomputer 5 will be described with reference to the flowchart shown in FIG. Step 101 is an initialization unit, in which the laser power P, the cruise flag indicating the operation state of the present apparatus, and the stop flag indicating the running mode of the vehicle are set to “0”. In step 102 following this, the vehicle speed V by the vehicle speed sensor 35 and the inter-vehicle distance L by the radar device 3 are input, and the routine proceeds to step 103. In step 103, if the vehicle speed V is less than the first predetermined value (for example, 5 km / h) Vl, the process proceeds to step 104, and if the inter-vehicle distance L is less than the first predetermined value (for example, 5m) Ll, In the stop mode, which is a substantially stop state, the stop flag is set to “1” in step 105. In steps 103 and 104, when V ≧ V1 and L ≧ L1, respectively, the process proceeds to step 106, and the stop flag is set to “0”. The above steps 102 to 105 and 106 are a stop flag setting section. In the next step 107, it is determined whether or not the set switch 27 for starting the tracking operation for the preceding vehicle is ON. If it is ON, it is determined in step 109 whether or not the stop flag is "1". Proceeding to step 111, the cruise flag is set to "1", and if it is "0", proceeding to step 113. Even if the set switch 27 is OFF in step 107, the process proceeds to step 113. The above steps 107 to 111 are a cruise flag setting section. In step 113, the brake switch 31 and the shift switch 33 are determined. In the next steps 115 and 117, the vehicle speed V is equal to or higher than a second predetermined value (for example, 30 km / h) Vh or the inter-vehicle distance L is set to a second predetermined value ( For example, 30 m) Lh or more is determined. If both the brake switch 31 and the shift switch 33 are ON in step 113, step 11
When V ≧ Vh in 5 and L ≧ Lh in step 117, the process proceeds to step 119, where the cruise flag is set to “0”. If the above conditions are not satisfied in the above steps 113, 115 and 117, the process directly proceeds to step 121. Steps 113 to 119 described above correspond to a cruise flag setting unit. At step 121 which is a cruise flag check section, it is determined whether or not the cruise flag is "0". When it is "0", the monitor 51 is turned off at step 123 to indicate that the apparatus is in the released state. To set the laser power P to low output Pl, and return to step 102 of the stop flag setting section. When the cruise flag is "1" in step 121, the monitor 51 is turned on in step 127, indicating that the apparatus is in the operating state, and proceeds to step 129. In step 129, the state of the stop flag is determined,
When this is "1", the vehicle is in the stop mode, and therefore step 13
When 0, the laser power is set to low output Pl. When the stop flag becomes “1” and the vehicle is in the stop mode, the vehicle speed V becomes the first predetermined value Vl.
And the inter-vehicle distance L must be as small as less than the first predetermined value Ll, so that the inter-vehicle distance can be accurately measured even with low-power laser light irradiation. On the other hand, when the stop flag in step 129 is “0”, the tracking mode is set, and in step 131, the laser power is set to Ph of high output. In the tracking mode in which the stop flag is “0”, the vehicle speed V is equal to or higher than the first predetermined value Vl, or if the vehicle speed V is lower than the first predetermined value Vl, the inter-vehicle distance L is equal to the first predetermined value. When the inter-vehicle distance L is large, the measurement of the inter-vehicle distance can be performed irrespective of the vehicle speed (at low speeds) by outputting a high-power laser beam under such conditions. (Even though). As described above, the microcomputer 5 determines whether or not the own vehicle is in a substantially stopped state (stop mode) based on the own vehicle speed in a normal traveling state (tracking mode),
When the determination unit determines that the vehicle is in a substantially stopped state and the inter-vehicle distance detected by the radar device 3 is short, a control unit that lowers the output of the radar device 3 is included. In the next step 132, the target (appropriate) according to the vehicle speed V
The formula Ls = 2V which expresses the following distance Ls by the graph shown in FIG.
The value is obtained as /3+2.5, and the process proceeds to step 133. In step 133, the throttle operation actuator 41 and the brake operation actuator 43 are determined according to the error ε (= Ls−L) of the actual inter-vehicle distance L with respect to the appropriate inter-vehicle distance Ls obtained in step 132.
, And outputs a throttle operation signal and a brake signal, respectively, and returns to step 102 of the stop flag setting section. As a result, the throttle 47 and the brake 29 operate, and the appropriate inter-vehicle distance Ls is obtained. By repeating the above flow at predetermined intervals (for example, every 100 msec), unnecessary operation of the radar device 3, that is, high output of laser power when the inter-vehicle distance is short, is prevented, and the vehicle speed is low. However, when the inter-vehicle distance is large, the laser power is not reduced, so that the inter-vehicle distance can be accurately measured. Figure 5 is a time chart showing a road example during operation of the device, t ₂ ~t ₃ and t ₄ 2 two intervals tracking mode of ~t _5, t ₁ ~t ₂ and t ₃ ~t ₄ The two sections are in the stop mode. [Effects of the Invention] As described above, according to the present invention, the output of the radar means is set to a low output when the host vehicle is in a substantially stopped state and the inter-vehicle distance is short. In addition to preventing unnecessary operation of the radar means, the output of the radar means is maintained at a predetermined output regardless of the own vehicle speed when the inter-vehicle distance is large,
Even when the own vehicle speed is low, the inter-vehicle distance to the preceding vehicle can be accurately measured.

BRIEF DESCRIPTION OF THE DRAWINGS The accompanying drawings relate to an embodiment of the present invention, FIG. 1 is a block diagram of an auto cruise system, FIG. 2 is a correlation diagram between a distance between vehicles and a required laser power, and FIG. Fig. 4 is a correlation diagram between the speed of the host vehicle and a target (appropriate) inter-vehicle distance, Fig. 4 is a flowchart, Fig. 5 is a time chart showing an example of traveling on a road, and Fig. 6 is a claim correspondence diagram. 3 ... Radar device (radar means) 5 ... Microcomputer (arithmetic processing means, judgment means, control means) 35 ... Vehicle speed sensor (speed detecting means) 41 ... Throttle actuating actuator (speed increasing / decreasing mechanism) 43 ... brake Actuator (speed increase / decrease mechanism)

Claims (1)

(57) [Claims] Radar means for detecting the inter-vehicle distance to the preceding vehicle, speed detecting means for detecting the speed of the own vehicle, and a speed command to the speed increasing / decreasing mechanism so as to maintain an appropriate inter-vehicle distance based on the inter-vehicle distance and the own vehicle speed. Determining means for determining whether the own vehicle is in a substantially stopped state or a normal running state based on the own vehicle speed detected by the speed detecting means; Control means for reducing the output of the radar means when the inter-vehicle distance detected by the means is substantially stopped and the inter-vehicle distance detected by the radar means is small.