JP2006347402A - Relative speed calculation device and inter-vehicle distance controller - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a relative speed calculation device for quickly recognizing the relative speed of an own vehicle and a preceding vehicle and an inter-vehicle distance controller for performing satisfactory acceleration/deceleration with high responsiveness. <P>SOLUTION: This relative speed calculation device is provided with an inter-vehicle distance detecting means 100, a relative speed calculation means 108 for calculating the relative speed information of an own vehicle and a preceding vehicle based on inter-vehicle distance information and a filter means 109 for filtering the calculated relative speed information. This relative speed calculation device is provided with a switching means 20 for, when the change rate of the calculated relative speed calculation value is a predetermined value or larger, or when the change rate of the filtered relative speed information is a predetermined value or larger, outputting almost 0 as a relative speed, and for, when the change rate of the calculated relative speed calculation value is a predetermined value or larger, or when the change rate of the filtered relative speed information is a predetermined value or smaller, outputting the filtered relative speed information as a relative speed, whereby the relative speed is decided based on the output value of the switching means. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention is set according to a relative speed calculation device and a relative speed suitable for use in an auto cruise control device or the like for automatically driving a vehicle at a predetermined speed and calculating a relative speed between the host vehicle and another vehicle. The present invention relates to an inter-vehicle distance control device that maintains the inter-vehicle distance.

In recent years, a technique for controlling the traveling of a vehicle based on distance information between the subject vehicle and an object (another vehicle) in front of or behind the subject vehicle has been developed. For example, the vehicle is automatically set at a set speed. 2. Description of the Related Art An auto cruise device that travels at a constant speed has been put into practical use with an inter-vehicle distance control function that maintains a predetermined inter-vehicle distance from a preceding vehicle that is traveling in front of the host vehicle.
In such an auto cruise device with an inter-vehicle distance control function, the presence or absence of a preceding vehicle and the preceding vehicle are detected or detected when there is a preceding vehicle, and are set when no preceding vehicle is detected. When the preceding vehicle is detected, the inter-vehicle distance control is performed to maintain the inter-vehicle distance at a predetermined distance based on the detected inter-vehicle distance information.

  In this inter-vehicle distance control, feedback control for accelerating or decelerating the host vehicle is performed so that the detected inter-vehicle distance information becomes a target inter-vehicle distance (predetermined distance). Although the target inter-vehicle distance can be set to a fixed distance in the simplest case, it is preferable to set a target inter-vehicle distance (predetermined distance) according to the vehicle speed of the host vehicle. In this case, of course, the target inter-vehicle distance is set larger as the vehicle speed of the host vehicle is higher.

In addition, a technique using the relative speed between the host vehicle and the preceding vehicle for such inter-vehicle distance control has been proposed (see, for example, Patent Documents 1 and 2).
For example, Patent Document 1 discloses a technique for controlling the vehicle speed of the host vehicle based on the difference between the inter-vehicle distance information between the host vehicle and the preceding vehicle and the target inter-vehicle distance and the relative speed between the host vehicle and the preceding vehicle. Has been.

In such an inter-vehicle distance control device, the inter-vehicle distance between the host vehicle and the object is detected by an inter-vehicle distance sensor such as a laser radar or a camera.
The inter-vehicle distance information detected by these inter-vehicle distance detection sensors is usually output as an analog signal such as a voltage value. However, if the detected signal is used as it is, the influence of noise or the like is large, and it is difficult to perform stable control. Therefore, in the ECU (electronic control unit) of the vehicle, the inter-vehicle distance information input from the inter-vehicle distance sensor to the ECU. The signal is filtered to smooth the signal.

This filtering process is performed at regular intervals (for example, 20 milliseconds) by a generally used low-pass filter (LPF).
Then, the relative speed information between the host vehicle and the preceding vehicle is calculated by differentiating the inter-vehicle distance information (filtered inter-vehicle distance information) obtained by filtering the inter-vehicle distance sensor signal and performing stabilization using a differentiation circuit or the like. It has come to be.

However, since the differential signal value (relative speed calculation value) is greatly affected by slight fluctuations in the signal value before differentiation (filtered inter-vehicle distance information), the relative speed calculation value has a lot of noise. It will be included. For this reason, the ECU sets the target inter-vehicle distance using the input relative speed information (relative speed calculation value) that has been subjected to filtering again to smooth and stabilize the signal value (see the thick solid line in FIG. 6). And acceleration / deceleration control of the vehicle.
JP 2004-127926 A JP 2000-285395 A

By the way, the inter-vehicle distance sensor normally detects the inter-vehicle distance information for the object closest to the own vehicle in the detectable range of the inter-vehicle distance sensor without being limited to a specific target object (preceding vehicle or subsequent vehicle). ing.
For example, when an interrupting vehicle appears between the host vehicle and a preceding vehicle traveling in front of the host vehicle, the inter-vehicle distance sensor detects the target object for detecting the inter-vehicle distance information from the time when the interrupting vehicle is detected. The signal value of the inter-vehicle distance information is output by switching to the interrupting vehicle.

As a result, the signal value of the inter-vehicle distance information output from the inter-vehicle distance sensor rapidly changes from the value of the inter-vehicle distance information for the preceding vehicle when there is no interrupting vehicle to the value of the inter-vehicle distance information for the interrupting vehicle. . Such a sudden change in the inter-vehicle distance also occurs when the preceding vehicle or the following vehicle changes lanes or when the vehicle deviates from the host vehicle lane due to a branch or the like.
However, the inter-vehicle distance information from the inter-vehicle distance sensor is output as a continuous signal even when the inter-vehicle distance information changes suddenly due to the change of the detection target. For this reason, when the relative speed is calculated by differentiating the inter-vehicle distance information when the inter-vehicle distance information suddenly changes, the calculated value is an extremely high (or extremely low) value. For example, when the detected distance between vehicles suddenly changes from 100 meters to 20 meters due to an interruption or the like, the differentiation circuit performs the differentiation operation on the assumption that the distance between vehicles is reduced by 80 meters within one calculation cycle (20 milliseconds). Therefore, in this case, the calculated relative speed becomes an extremely large value of 4000 m / s. On the contrary, when the distance between the vehicles suddenly changes from 20 meters to 100 meters, the calculated relative speed is − This is an extremely low value of 4000 m / s. However, since a specific preceding vehicle has not suddenly approached or moved away in practice, a value that does not match the actual condition is calculated.

  Further, when the signal is filtered, the value calculated by the filter (LPF) is calculated based on the current signal value and the calculated value calculated one calculation cycle ago. It is cumulatively affected by the relative speed calculation value in each previous cycle. Of course, this influence increases as the latest relative velocity calculation value increases, and the earlier filtered signal value decreases, so the convergence tends to occur with each cycle. However, the more extreme the value, the longer the convergence. .

  For this reason, as shown in FIG. 6, once the relative speed calculated value takes an extreme value, the influence will occur over many cycles. FIG. 6 shows a case where there is an interruption to the own vehicle lane of another vehicle at time T1, and this interruption vehicle has left the own vehicle lane at time T2. In such a case, the inter-vehicle distance information of the vehicle changes abruptly, and the relative speed calculation value (differential value of the inter-vehicle distance information) becomes an extremely large value at the time point T1, and becomes an extremely small value at the time point T2. turn into. Further, the post-filter signal value is influenced by the extreme value at this time, and until the post-filter signal value becomes close to the pre-filter signal value, a certain time difference (ΔT1, ΔT2) as shown in FIG. ) Will occur.

  As described above, when the inter-vehicle distance signal output from the inter-vehicle distance sensor changes suddenly due to interruption or the like, the relative speed calculation value calculated based on the inter-vehicle distance signal is an incorrect value that does not match the actual situation. There has been a problem that the relative speed that does not match the actual condition continues to be calculated over a plurality of periods by performing calculation and filtering to remove noise. Furthermore, there is a problem that the inter-vehicle distance control is performed based on erroneous information (relative speed that does not match the actual state) by erroneously recognizing the actual relative speed over a plurality of cycles.

  The present invention has been devised in view of such problems, and can be suitably used for an auto cruise control device or the like, and can eliminate noise included in a differential value (relative speed calculation value) of inter-vehicle distance information. In addition, even if a relative speed calculation value that does not match the actual condition is calculated even if the inter-vehicle distance information is differentiated due to an interruption of the preceding vehicle or a lane change of the host vehicle, an accurate relative speed that matches the actual condition is calculated. An object of the present invention is to provide a relative speed calculation device and an inter-vehicle distance control device that can quickly calculate the vehicle speed.

  In order to achieve the above-described object, the relative speed calculation device according to the first aspect of the present invention is an inter-vehicle distance detection unit that detects inter-vehicle distance information between the host vehicle and another vehicle traveling in front of or behind the host vehicle. A relative speed calculation means for calculating relative speed information between the host vehicle and the other vehicle based on the inter-vehicle distance information, a filter means for filtering the relative speed information calculated by the relative speed calculation means, A rate of change of the relative speed calculated value calculated by the relative speed calculating means is greater than or equal to a predetermined value, or a rate of change of the filtered relative speed information filtered by the filter means is predetermined. When the value is equal to or greater than the value, approximately 0 is output as the relative speed, and when the rate of change of the relative speed calculation value calculated by the relative speed calculation means is equal to or greater than a predetermined value or the filter processed by the filter means. When the rate of change of the post-filter relative speed information is less than a predetermined value, a switching means for outputting the post-filter relative speed information as a relative speed is provided, and the relative speed is determined based on the output value of the switching means. It is a feature.

According to a second aspect of the present invention, there is provided the relative speed calculation device according to the first aspect of the present invention, wherein the filter means calculates and filters the relative speed calculation value at a preset calculation cycle. Thus, the filtered relative speed information F (n) in the calculation cycle n, the relative speed calculation value L (n) in the calculation cycle n, and the post-filter relative speed information F in the calculation cycle (n−1) one calculation cycle before. (N-1) is
F (n) = aF (n−1) + bL (n) (1)
However, a + b = 1, 0 <a, 0 <b
It is characterized by satisfying the relationship.

  According to a third aspect of the present invention, there is provided the relative speed calculation device according to the second aspect of the present invention, wherein the switching means is based on the rate of change of the calculated relative speed calculated by the relative speed calculation means or the filter means. In the calculation cycle in which the rate of change of the filtered relative speed information subjected to the filtering process is equal to or greater than a predetermined value, the filtered relative speed information is set to 0, and the filtering means sets the filtered relative speed information set by the switching means. It is characterized in that a filtering process after the calculation cycle is performed based on the information.

According to a fourth aspect of the present invention, there is provided the relative speed calculation device according to the second or third aspect of the present invention, wherein the rate of change of the relative speed calculation value is obtained from the relative speed calculation means in a calculation cycle n. Detected based on the difference between the relative speed calculation value L (n) and the relative speed calculation value L (n-1) obtained from the relative speed calculation means in the calculation period (n-1) one calculation period before. It is characterized by that.
According to a fifth aspect of the present invention, there is provided a relative speed calculation device according to any one of the first to fourth aspects, wherein the inter-vehicle distance filter means filters the inter-vehicle distance information detected by the inter-vehicle distance detection means. The relative speed calculation means calculates the relative speed information based on the filtered inter-vehicle distance information filtered by the inter-vehicle distance filter means.

  The inter-vehicle distance control apparatus according to the sixth aspect of the present invention detects inter-vehicle distance information between acceleration / deceleration means for accelerating or decelerating the host vehicle and a preceding vehicle traveling in front of the host vehicle. An inter-vehicle distance detecting means, a relative speed calculating means for calculating a relative speed between the host vehicle and the preceding vehicle based on the inter-vehicle distance information detected by the inter-vehicle distance detecting means, and a relative speed calculated by the relative speed calculating means If the rate of change of the filter means for filtering information and the relative speed information or the rate of change of the filtered relative speed information filtered by the filter means is equal to or greater than a predetermined value, 0 is output and the relative speed is output. When the rate of change of information or the rate of change of relative speed information after filtering is less than the predetermined value, switching means for outputting the filtered relative speed information, and calculating the relative speed based on the output value of the switching means A post-filter relative speed calculating means; and an acceleration / deceleration control means for operating the acceleration / deceleration means based on the relative speed calculated by the post-filter relative speed calculating means. It is characterized by filtering based on this.

  According to a seventh aspect of the present invention, in the inter-vehicle distance control device according to the sixth aspect of the present invention, the vehicle speed detecting means for detecting the vehicle speed of the host vehicle and the target inter-vehicle distance between the host vehicle and the preceding vehicle are set. Based on the target vehicle distance setting means, the vehicle speed detected by the vehicle speed detection means, the target vehicle distance set by the target vehicle distance setting means, and the output value of the switching means. Target acceleration speed setting means, and the acceleration / deceleration control means accelerates or decelerates the host vehicle according to the target speed.

  Therefore, according to the relative speed calculation apparatus of the first aspect of the present invention, in the normal time when there is no sudden change in the inter-vehicle distance information due to the lane change or the like, the calculated relative speed calculation value is filtered to suppress the influence of noise. On the other hand, when the rate of change of the relative speed information calculated by the sudden change in the inter-vehicle distance information is equal to or greater than a predetermined value, the filtered relative speed information is set to 0. It is possible to suppress calculation of an incorrect relative speed that does not match the above.

According to the relative speed calculation device of the present invention as set forth in claim 2, in addition to the effect of claim 1, the noise included in the relative speed calculation value is surely removed and stable relative speed information is calculated. be able to.
According to the relative speed calculation device of the present invention described in claim 3, in addition to the effect of claim 2, when the relative speed suddenly changes, the relative speed is recognized as 0, and based on this, in the subsequent calculation cycle, Since the filter processing is performed, the calculation after the relative speed sudden change is not affected by the calculation of the relative speed calculated suddenly in the calculation of not only the calculation period but also the subsequent calculation period. The post-filter relative speed information calculated in the period converges to a value close to the relative speed calculation value, and the responsiveness can be improved. In addition, noise included in the calculated relative speed is also reliably removed, and stable filtered relative speed information can be obtained.

According to the relative speed calculation device of the present invention described in claim 4, in addition to the effect of claim 2 or 3, the change rate of the relative speed calculation value is expressed as a current value and a relative speed calculation value before one calculation cycle. It is possible to quickly and reliably detect the difference.
According to the fifth aspect of the present invention, in addition to the effects of the first to fourth aspects, the inter-vehicle distance filter means filters the inter-vehicle distance information detected by the inter-vehicle distance detection means. Noise contained in the information is surely removed, and stable after-filter distance information can be obtained. Furthermore, since the relative speed calculation means calculates the relative speed calculation value based on the filtered inter-vehicle distance, the relative speed can be determined based on a stable relative speed calculation value with a small noise amplitude.

Further, according to the inter-vehicle distance control device of the present invention described in claim 6, since the own vehicle is accelerated / decelerated based on the relative speed more suited to the actual situation, the detection value of the inter-vehicle distance sensor changes suddenly due to a lane change or the like. Even in such a case, since the relative speed is accurately determined and the own vehicle is accelerated / decelerated, a good inter-vehicle distance control can be performed.
According to the inter-vehicle distance control device of the seventh aspect of the present invention, in addition to the effect of the sixth aspect, the target speed of the host vehicle that is the target based on the vehicle speed of the host vehicle, the target inter-vehicle distance, and the relative speed is determined. Since it is set, the host vehicle can be accelerated or decelerated promptly according to the target speed.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
1 to 5 are diagrams for explaining a relative speed calculation device and an inter-vehicle distance control device according to an embodiment of the present invention. FIG. 1 is a block diagram showing the configuration, and FIG. 2 is an inter-vehicle distance. FIG. 3 is a circuit diagram schematically showing an arithmetic circuit relating to filter processing of the functional configuration and relative speed calculation value in the ECU, and FIG. FIG. 5 is a flowchart illustrating the change over time in the relative speed information (relative speed calculation value) and the filtered signal value in the present embodiment.

In the present embodiment, the relative speed calculation device and the inter-vehicle distance control device of the present invention are applied to an auto cruise control device. In this automatic cruise control device, when there is no preceding vehicle ahead of the host vehicle, or when the inter-vehicle distance D between the host vehicle and the preceding vehicle is sufficiently wider than the inter-vehicle distance control start threshold Ds, the vehicle is set at the set speed V0. When the vehicle travels automatically at a constant speed (constant speed control mode) and the inter-vehicle distance D is shorter than the inter-vehicle distance control start threshold Ds, the traveling speed of the host vehicle is maintained so that the inter-vehicle distance D maintains the target inter-vehicle distance Dt. To control the inter-vehicle distance (inter-vehicle distance control mode).
The inter-vehicle distance control start threshold Ds may be set to the detection limit value of the inter-vehicle distance sensor or may be set to be shorter than the detection limit value.

  As shown in FIG. 1, the auto cruise control device according to the present embodiment includes an ECU (electronic control device) 150 including a memory (ROM, RAM) and a CPU, an inter-vehicle distance detection means (inter-vehicle distance sensor) 100, a vehicle speed. A sensor 101, a brake switch 102, a throttle opening sensor 103, and an operation switch 104 are provided, and a throttle actuator 105 and a brake actuator 106 are further provided.

The input side of the ECU 150 is connected to an inter-vehicle distance detecting means 100, a vehicle speed sensor 101, a brake switch 102, a throttle opening sensor 103, and an operation switch 104. On the output side of the ECU 150, a throttle actuator 105 and a brake actuator 106 are connected. It is connected.
A vehicle speed sensor 101, a brake switch 102, and a throttle opening sensor 103 are sensors for detecting information on the traveling speed of the host vehicle, on / off of a brake pedal (not shown), and the opening of a throttle valve, respectively. The operation switch 104 is a switch for instructing the ECU 150 to start auto-cruise control. When the driver turns on the operation switch 104, the traveling vehicle speed at that time is set to the set vehicle speed V0 and the auto-cruise control is started. It is like that. The operation switch 104 is also provided with a function that can increase or decrease the set vehicle speed V0 during auto-cruising.

In addition, the auto-cruise control can be released by turning off the operation switch 104, but the auto-cruise control is also released by the brake operation detected from the signal of the brake switch 102.
The inter-vehicle distance detection means (inter-vehicle distance sensor) 100 is a sensor that detects the presence of an object (preceding vehicle) ahead of the host vehicle and the inter-vehicle distance between the host vehicle and the preceding vehicle, for example, using a laser radar or the like. The inter-vehicle distance information is output as a voltage value signal. Here, the detection limit value of the inter-vehicle distance sensor 100 is 150 meters, and when there is no preceding vehicle or the inter-vehicle distance is equal to or greater than the detection limit value, the inter-vehicle distance detection means sets the detection limit value (150 meters) to the inter-vehicle distance. It is output as distance information.

The ECU 150 includes, as functional elements, an inter-vehicle distance LPF 107, a differentiation circuit (relative speed calculating means) 108, a relative speed LPF (low-pass filter as a filter means) 109, a target inter-vehicle distance setting means 110, a target vehicle speed calculating means (target vehicle speed setting means). ) 111 and acceleration / deceleration control means 112.
The inter-vehicle distance detection signal input from the inter-vehicle distance detection means 100 to the ECU 150 is filtered by the inter-vehicle distance LPF 107. As a result, minute fluctuations (noise) included in the inter-vehicle distance detection signal (inter-vehicle distance information) are removed and converted into stable signal values (filtered inter-vehicle distance information) with little unnecessary fluctuations. The filtered inter-vehicle distance information is input to the target vehicle speed calculation unit 111.

The filtered inter-vehicle distance information filtered by the inter-vehicle distance LPF 107 is also input to a differentiating circuit (relative speed calculating means) 108. The differentiating circuit 108 performs a differentiation process on the inputted post-filter inter-vehicle distance information, and calculates relative speed information (relative speed calculated value).
Then, the calculated relative speed calculated value is input to the relative speed LPF 109 for filtering. As a result, minute fluctuations (noise) included in the relative speed calculation value output from the differentiating circuit 108 are removed and converted into stable signal values (filtered relative speed information) with less unnecessary fluctuations. Then, the final relative speed is calculated in consideration of the change amount of the output value from the differentiation circuit 108.
Details of the filtering process and the relative speed calculation calculation will be described later.

The target inter-vehicle distance setting means 110 stores information on the target inter-vehicle distance as a map corresponding to the vehicle speed V of the host vehicle input from the vehicle speed sensor 101. Based on the vehicle speed V of the host vehicle, the target An inter-vehicle distance (target inter-vehicle distance) D0 is set.
When the inter-vehicle distance (filtered inter-vehicle distance information) D input from the inter-vehicle distance LPF 107 is equal to or greater than the inter-vehicle distance control start threshold Ds, the target vehicle speed calculation unit 111 indicates that there is no preceding vehicle ahead of the own vehicle or the own vehicle And the preceding vehicle is determined to be sufficient, the auto cruise set vehicle speed V0 is set to the target vehicle speed Vt and sent to the acceleration / deceleration control means 112 (constant speed mode).

If the inter-vehicle distance D is smaller than the inter-vehicle distance control start threshold Ds, the inter-vehicle distance Dn in the calculation cycle n, the relative speed (filtered relative speed information) ΔVn input from the relative speed LPF 109, the target inter-vehicle distance setting means Based on the target inter-vehicle distance Dtn input from 110 and the vehicle speed Vn of the host vehicle input from the vehicle speed sensor 102, ΔVn = Dn−Dn−1 (A)
Vtn = Vn + a (Dn−Dtn) + bΔVn (B)
The target vehicle speed Vt is calculated by performing the following calculation. However, when the calculated target vehicle speed Vt is higher than the auto-cruise set vehicle speed V0, the set vehicle speed V0 is set to the target vehicle speed Vt. The target vehicle speed Vt thus set is input to the acceleration / deceleration control means 112.

The relative speed ΔV is positive in the direction in which the inter-vehicle distance between the host vehicle and the preceding vehicle increases as shown in the above equation (a). Further, a and b are appropriately set filter coefficients.
Then, the acceleration / deceleration control means 112 performs feedback control for accelerating or decelerating the host vehicle so that the input vehicle speed V of the host vehicle becomes the target vehicle speed Vt. Thus, in the constant speed mode, the own vehicle travels at the set vehicle speed V0, and in the inter-vehicle distance control mode, the inter-vehicle distance between the own vehicle and the preceding vehicle is maintained at the target inter-vehicle distance D0.

Next, referring to FIG. 2 to FIG. 5, the calculated relative speed information (also referred to as a filtered signal value) and the relative speed calculation means in the filtered relative speed acquisition means 113 including the inter-vehicle distance LPF 107 and the relative speed LPF 109. The calculation of the relative speed in will be described.
As shown in FIG. 2, the inter-vehicle distance LPF 107 includes a first amplifier 301, a second amplifier 302, a delay element 303, an adder circuit 304, and a signal recognition unit 305.

The signal (voltage value) of the inter-vehicle distance information detected by the inter-vehicle distance sensor 100 is first input to the signal recognition unit 305 of the inter-vehicle distance LPF 107, and the signal recognition unit 305 performs every calculation cycle (here, 20 milliseconds). The input inter-vehicle distance detection signal value is recognized, and the recognized value is output as the inter-vehicle distance detection signal value Ld (n).
The first amplifier 301 is interposed between the delay element 303 and the adder circuit 304, and the second amplifier 302 is interposed between the signal recognition unit 305 and the adder circuit 304, respectively. The amplifier 302 outputs values obtained by multiplying the input signal values by set filter coefficients ad and bd (where ad + bd = 1, ad> 0, bd> 0).

  The filter coefficients ad and bd are values set in advance so as to sufficiently remove a minute change (noise) of the detection signal value Ld (n). In this case, the larger the filter coefficient ad (the smaller the filter coefficient bd) is, the larger noise can be removed, but the response delay with respect to the change in the inter-vehicle distance detection signal value Ld (n) increases, so the values of the filter coefficients ad and bd are noise. Can be reliably removed, and at the same time, the response delay with respect to the change in the inter-vehicle distance detection signal value Ld (n) is set so as not to become so large.

  A signal value is input to the adder circuit 304 from the first amplifier 301 and the second amplifier 302, and the input signal value is added and output. The element 303 is interposed between the adder circuit 304 and the first amplifier 301, and the delay element 303 uses the signal value (that is, the filtered inter-vehicle distance information) input from the adder circuit 304 for one calculation cycle (20 milliseconds). ) Output is delayed.

  Therefore, the inter-vehicle distance detection signal value Ld (n) input from the signal recognition unit 305 to the second amplifier 302 is converted into a signal value adLd (n) multiplied by the filter coefficient ad by the second amplifier 302 and is added to the adder circuit 304. The first amplifier 301 receives the filtered signal value Fd (n−1) one calculation cycle before from the delay element 303, and the input filtered signal value Fd (n−1) one calculation cycle before. Is converted to a signal value bdFd (n−1) multiplied by the filter coefficient bd by the first amplifier 301 and input to the adder circuit 304.

The adder circuit 304 adds the signal value bdFd (n−1) input from the first amplifier 301 and the signal value adLd (n) input from the second amplifier 302, and adds the signal value bdF (n− 1) Output + adL (n).
That is, when viewed as the entire inter-vehicle distance LPF 107, the input inter-vehicle distance detection signal value Ld (n) is expressed as Fd (n) = bdFd (n−1) + adLd (n) (C)
And output from the inter-vehicle distance LPF 107.

The filtered inter-vehicular distance information Fd (n) filtered for each computation cycle in the inter-vehicle distance LPF 107 is input to the differentiating circuit (relative speed calculating means) 108 and the target vehicle speed setting means 111.
The differentiating circuit 108 is generally used and includes a capacitor and an amplifying circuit (not shown). In the differentiating circuit 108, the rate of change (that is, the differential value) of the after-filter inter-vehicle distance information Fd (n) input every calculation cycle is calculated. The differential value Lr (n) of the post-filter inter-vehicle distance information includes the post-filter inter-vehicle distance signal value Fd (n) input in the calculation cycle n and the post-filter inter-vehicle distance signal value Fd (n−) input one calculation cycle before. It is calculated | required by calculating the difference with 1).

The change rate Lr (n) of the post-filter inter-vehicle distance information calculated in the differentiating circuit 108 indicates the speed difference (relative speed) between the host vehicle and the preceding vehicle. That is, the differentiating circuit 108 calculates the relative speed information from the inter-vehicle distance information every calculation cycle, and inputs it to the post-filter relative speed acquisition means 113 including the relative speed LPF 109.
As shown in FIG. 3, the post-filter relative speed acquisition unit 113 includes a relative speed LPF 109, a zero value setting unit 205, a relative speed change determination unit 206, and a switch (switching unit) 207.

The relative speed LPF 109 includes a first amplifier 201, a second amplifier 202, a delay element 203, and an adder circuit 204.
The first amplifier 201 and the second amplifier 202 output values obtained by multiplying the input signal values by filter coefficients a and b (where a + b = 1, a> 0, b> 0), respectively. ing.

  The filter coefficients a and b are values set in advance so that a minute change (noise) of the relative speed calculation value Lr (n) can be sufficiently removed. In this case, as in the case of the inter-vehicle distance LPF 107, the larger the filter coefficient a (the smaller the filter coefficient b) is, the larger noise can be removed, but the response delay with respect to the change in the relative speed calculation value Lr (n) increases. The values of the coefficients a and b are set to such values that noise can be reliably removed and at the same time the response delay with respect to the change in the relative speed calculation value Lr (n) is not increased.

  The delay element 203 is interposed between the switch 207 and the first amplifier 201, and the delay element 203 delays the signal value input via the switch 207 by one calculation cycle (20 milliseconds) and outputs it. The adder circuit 204 receives signal values from the first amplifier 201 and the second amplifier 202, and adds and outputs the values of the input signal values.

Therefore, the relative speed calculation value Lr (n) input from the differentiating circuit 108 in the calculation cycle n is input to the second amplifier 202 and the relative speed change determination unit 206 of the relative speed LPF 109.
Then, the second amplifier 202 sends a signal value arLr (n) obtained by multiplying the input relative speed calculation value Lr (n) by the filter coefficient b to the adding circuit 204.

On the other hand, the first amplifier 201 receives the filtered signal value Fr (n−1) one calculation cycle before from the delay element 203, and the first amplifier 201 inputs the filtered signal value Fr (1 calculation cycle before the input). A signal value brF (n−1) obtained by multiplying n−1) by the filter coefficient br is sent to the adding circuit 204.
The adder circuit 204 adds the signal value brF (n−1) input from the first amplifier 201 and the signal value arLr (n) input from the second amplifier 202, and adds the signal value brFr (n− 1) Output + arLr (n).

That is, when the relative speed LPF 109 is viewed as a whole, the input relative speed calculated value Lr (n) is expressed as Fr (n) = brFr (n−1) + arLr (n) (D)
The filtered signal value F (n) is output.
One end of the output side of the switch 207 is fixed, and the other end of the input side is disposed so as to be able to switch connection / disconnection between the Y side terminal and the N side terminal by energizing a solenoid (not shown). The fixed output terminal is connected to the target vehicle speed calculation means 111 and the delay element 203 of the relative speed LPF 109, and the Y-side terminal as the input end is connected to the zero value setting means 205, and also at the input end. A certain N-side terminal is connected to the output side of the relative speed LPF 109.

The zero value setting means 205 always outputs a signal value indicating a relative speed of zero.
The relative speed change determination unit 206 receives the relative speed calculation value Lr (n) from the differentiating circuit 108, and the input relative speed calculation value Lr (n) is stored in a storage device inside the relative speed change determination unit 206. It is like that.

Further, the relative speed change determination unit 206 calculates the difference between the relative speed calculated value Lr (n) in the calculation cycle n and the stored relative speed calculated value Lr (n−1) one calculation cycle before. The magnitude relationship between the calculated value and a predetermined value S set in advance is compared.
When the difference between the relative speed calculation value Lr (n) and the relative speed calculation value Lr (n−1) one calculation cycle before is smaller than the predetermined value S (that is, when the rate of change of the relative speed calculation value is small). ), The switch 207 is connected to the terminal on the N side, and when the difference is equal to or greater than the predetermined value S (that is, when the rate of change of the relative speed calculation value is large), the switch 207 is connected to the terminal on the Y side. The switch 207 is controlled so as to be connected. The predetermined value S is a preset value.

Therefore, when the switch 207 is connected to the N-side terminal (that is, when | Lr (n) −Lr (n−1) | ≦ predetermined value S), the filtered signal value Fr ( n) is output and input to the target vehicle speed calculation means 111 and the delay element 203 of the relative speed LPF 109.
When the switch 207 is connected to the terminal on the Y side (that is, when | Lr (n) −Lr (n−1) |> predetermined value S), the relative speed 0 is set from the zero value setting means 205. At this time, the target vehicle speed calculation unit 111 and the delay element 203 of the relative speed LPF 109 recognize that the relative speed is zero.

  Since the relative speed calculation device and the inter-vehicle distance control device (particularly, the filtered relative speed acquisition means 113) according to the embodiment of the present invention are configured as described above, in step S01, as shown in FIG. The speed change determination unit 206 calculates the difference between the current relative speed calculation value Lr (n) and the relative speed calculation value Lr (n−1) one calculation cycle before, and the calculated difference is smaller than the predetermined value S. Determines that the rate of change of the inter-vehicle distance information (detection signal) detected by the inter-vehicle distance sensor 100 is smaller than a predetermined value, and proceeds to step S02.

In step S01, if the difference between the current relative speed calculated value Lr (n) and the relative speed calculated value Lr (n-1) one calculation cycle before is equal to or greater than the predetermined value S, the inter-vehicle distance sensor 100 is It is determined that the change rate of the detected inter-vehicle distance information (detection signal) is greater than a predetermined value, and the process proceeds to step S03.
In step S02, the relative speed change determining unit 206 connects the switch 207 to the N-side terminal, and based on the current relative speed calculated value Lr (n) and the filtered signal value Fr (n−1) one calculation cycle before. Thus, a filtered signal value F (n) obtained by performing an operation of Fr (n) = brFr (n−1) + arLr (n) (referred to as a filter operation) is output from the relative speed LPF 109 via the switch 207. At this time, ar + br = 1, ar> 0, br> 0.

In step S03, the relative speed change determination unit 206 connects the switch 207 to the terminal on the Y side, and a signal value indicating the relative speed 0 is output from the zero value setting unit 205. Then, the target vehicle speed calculation unit 111 and the delay element 203 of the relative speed LPF 109 recognize the relative speed information as 0.
By adding the post-filter signal value Fr (n-1) at a predetermined ratio, the detection signal that changes slightly is flattened to obtain stable post-filter relative speed information Fr (n). In 111, the target vehicle speed Vt can be set stably.

  Further, in the present embodiment, for example, as shown in FIG. 5, the inter-vehicle distance is drastically shortened due to the appearance of the interrupting vehicle at the time T1, or the inter-vehicle distance disappears at the time T2. In a calculation cycle in which the relative speed calculation value Lr (n) changes drastically due to a sudden increase in the distance between the vehicles, the relative speed recognition means recognizes the filtered relative speed information Fr (n) as 0. Therefore, when the filter calculation is performed in the subsequent calculation cycle, it is not affected by the relative speed calculation value Lr (n) of the extreme value before the sudden change of the inter-vehicle distance, and thus the filtered signal value Fr (n ) Is a value close to the relative speed calculation value Lr (n) that matches the actual condition immediately after the sudden change in the inter-vehicle distance calculation value, and unnecessary noise included in the relative speed calculation value Lr (n) is removed. On the other hand, relative speed information (filtered signal value) suitable for the actual situation can be input to the target vehicle speed calculation means 111, and the target vehicle speed calculation means 111 is not affected by the erroneous relative speed information so much and is stable. The target vehicle speed Vt can be set.

[Others]
Although the embodiments of the present invention have been described above, the present invention is not limited to the above-described embodiments, and various modifications can be made without departing from the spirit of the present invention.
In the above-described embodiment, the target vehicle speed setting unit 111 calculates the target vehicle speed using the filtered relative speed information, but the use of the filtered relative speed information is not limited to this.
For example, even when the target vehicle speed based on the relative speed information is not normally set and the acceleration or deceleration of the host vehicle is feedback-controlled by the throttle control based on the target inter-vehicle distance and the detected inter-vehicle distance, If the speed is negative and the absolute value is greater than or equal to a predetermined value (that is, if you are approaching the preceding vehicle rapidly), the vehicle may not be able to decelerate sufficiently by controlling the throttle alone. For example, when the relative speed is negative and the absolute value is greater than or equal to a predetermined value, a warning may be given to the driver, or deceleration by braking may be performed.

  Also, depending on the inter-vehicle distance sensor, when the inter-vehicle distance is long, the amplitude of noise included in the inter-vehicle distance detection signal may increase due to a decrease in detection accuracy of the sensor. It is conceivable that the amplitude of noise included in the speed calculation value also increases. As a result, there is a possibility that a change in the relative speed calculation value L (n) due to noise and a change in the relative speed calculation value L (n) due to a change in the actual relative speed are erroneously determined.

  In such a case, the value of the predetermined value S in the above-described embodiment may be set to a different value depending on whether the detection signal value Ld (n) of the inter-vehicle distance is large or small. At this time, naturally, when the inter-vehicle distance detection signal value Ld (n) is large, the value of the predetermined value S is set large, and when the inter-vehicle distance detection signal value Ld (n) is small, the value of the predetermined value S is set small. Further, the value of the predetermined value S may be set not only in two stages but also in two or more stages corresponding to the magnitude of the inter-vehicle distance detection signal value Ld (n).

Thereby, even when the inter-vehicle distance is long and the amplitude of the noise included in the detection signal of the inter-vehicle distance sensor becomes large, the fluctuation of the detection signal value due to the noise is not confused with the sudden change of the inter-vehicle distance. Further, when the inter-vehicle distance is long, the fluctuation amount of the inter-vehicle distance due to an interrupting vehicle or the like is generally large, so that the sudden change of the inter-vehicle distance can be accurately determined when the inter-vehicle distance changes suddenly.
In addition, even when the vehicle speed of the host vehicle is high, it is conceivable that the amplitude of noise included in the inter-vehicle distance detection signal increases due to sensor vibration or the like. Accordingly, the values of the filter coefficients ar, br and ad, bd in the above-described embodiment are not limited to constant values. For example, when the detection signal value Ld (n) (inter-vehicle distance) is large, the filter coefficients ar, ad are When the detection signal value Ld (n) is small by increasing it (decreasing the filter coefficients br and bd), the filter coefficients ar and ad may be set small (by increasing the filter coefficients br and bd). In this way, even when the inter-vehicle distance is large and the amplitude of the noise of the inter-vehicle distance detection signal is large, the noise can be surely removed. Processing can be performed.

  Further, in the above-described embodiment, the rate of change of the relative speed is calculated based on the relative speed calculated value Lr (n) and the relative speed calculated value Lr (n−1) one filter cycle before or the filtered signal value Fr (n) and 1 Although the determination is made by comparison with the filtered signal value Fr (n−1) before the calculation cycle, the current signal values Lr (n) and Fr (n) are used in order to more reliably determine the sudden change in the relative speed. And the signal values Lr (nt) and Fr (nt) (where t is an integer greater than or equal to 2) before t periods. In this case, the larger the value of t, the more reliable the determination can be. However, since the responsiveness to changes in the inter-vehicle distance deteriorates, it is desirable to set the value of t within a range that does not impair the responsiveness (for example, t = 2).

The relative speed calculation value also changes suddenly when the inter-vehicle distance information detected by the inter-vehicle distance detecting means 100 or the inter-vehicle distance information filtered by the inter-vehicle distance LPF 107 changes suddenly. When the difference from the previous inter-vehicle distance information is equal to or greater than a predetermined value, it may be determined that the change rate of the relative speed calculation value is greater than the predetermined change rate.
Further, it is needless to say that the time of the calculation cycle is not limited to that of the above-described embodiment (20 milliseconds) and can be changed as appropriate. Further, instead of or in addition to the condition that the rate of change of the relative speed is greater than or equal to a predetermined value, the absolute value of the relative speed may be greater than or equal to the predetermined value. This is also because it is possible to detect a sudden change in the output value of the inter-vehicle distance sensor due to a lane change or the like.

It is a block diagram which shows the structure of the auto-cruise control apparatus to which the relative speed calculation apparatus and the inter-vehicle distance control apparatus which concern on one Embodiment of this invention are applied. It is a circuit diagram showing typically the arithmetic circuit concerning filter processing by the inter-vehicle distance filter means in the relative speed calculation device and the inter-vehicle distance control device according to one embodiment of the present invention. It is a typical circuit diagram which shows the structure of the post-filter relative speed acquisition means in the relative speed calculation apparatus and the inter-vehicle distance control apparatus which concern on one Embodiment of this invention. It is a flowchart which shows the control in the filter control means based on one Embodiment of this invention. The graph for demonstrating the relative speed calculation apparatus and the inter-vehicle distance control apparatus which concern on one Embodiment of this invention, Comprising: An example of a time-dependent change of inter-vehicle distance information (relative speed calculation value) and a filtered signal value It is. It is a graph which shows an example of the time-dependent change of the signal value before a filter regarding the relative speed calculation value used for the conventional inter-vehicle distance control apparatus, and the signal value after a filter.

Explanation of symbols

100 Inter-vehicle distance detection means (inter-vehicle distance sensor)
101 Vehicle speed sensor 102 Brake switch 103 Throttle opening sensor 104 Operation switch 105 Throttle actuator 106 Brake actuator 107 Distance between vehicles LPF
108 Differentiation circuit 109 Relative speed LPF (filter means)
110 Target inter-vehicle distance setting means 111 Target vehicle speed calculation means (target vehicle speed setting means)
112 Acceleration / deceleration control means 113 Filtered relative speed acquisition means 150 ECU
201 First amplifier 202 Second amplifier 203 Delay element 204 Adder circuit 205 Zero value setting means 206 Relative speed change determination unit 207 Switch (switching means)
301 1st amplifier (vehicle distance)
302 Second amplifier (distance between vehicles)
303 Delay element (distance between vehicles)
304 Adder circuit (distance between vehicles)
305 Signal recognition part

Claims (7)

An inter-vehicle distance detecting means for detecting inter-vehicle distance information between the own vehicle and another vehicle traveling in front of or behind the own vehicle;
Relative speed calculation means for calculating relative speed information between the host vehicle and the other vehicle based on the inter-vehicle distance information;
Filter means for filtering the relative speed information calculated by the relative speed calculation means;
In a relative speed calculation device comprising:
When the change rate of the relative speed calculation value calculated by the relative speed calculation means is greater than or equal to a predetermined value, or when the change rate of the filtered relative speed information filtered by the filter means is greater than or equal to a predetermined value, the relative speed is When the change rate of the relative speed calculation value calculated by the relative speed calculation means is less than a predetermined value or the change rate of the filtered relative speed information filtered by the filter means is less than the predetermined value. When equipped with a switching means for outputting the post-filter relative speed information as a relative speed,
A relative speed calculation device that determines the relative speed based on an output value of the switching means. The filter means calculates the relative speed calculation value at a preset calculation cycle and performs filtering.
Relative speed information F (n) after filtering in the calculation period n, a calculated relative speed value L (n) in the calculation period n, and relative speed information F (n) after filtering in the calculation period (n−1) one calculation period before -1)
F (n) = aF (n−1) + bL (n) (1)
However, a + b = 1, 0 <a, 0 <b
The relative velocity calculation apparatus according to claim 1, wherein the relationship is satisfied. In the calculation cycle in which the change rate of the relative speed calculation value calculated by the relative speed calculation unit or the change rate of the filtered relative speed information filtered by the filter unit is a predetermined value or more, the switching unit 3. The post-filter relative speed information is set to 0, and the filter means performs filter processing after the calculation cycle based on the post-filter relative speed information set by the switching means. Relative speed calculation device. The rate of change of the relative speed calculation value is calculated based on the relative speed calculation value L (n) obtained from the relative speed calculation means in the calculation cycle n and the relative speed in the calculation cycle (n−1) one calculation cycle before. 4. The relative speed calculation device according to claim 2, wherein the relative speed calculation device is detected based on a difference from the relative speed calculation value L (n-1) obtained from the calculation means. An inter-vehicle distance filter means for filtering the inter-vehicle distance information detected by the inter-vehicle distance detection means;
5. The relative speed calculation unit calculates the relative speed information based on the filtered inter-vehicle distance information filtered by the inter-vehicle distance filter unit. 6. Relative speed calculation device. Acceleration / deceleration means for accelerating or decelerating the vehicle;
Inter-vehicle distance detection means for detecting inter-vehicle distance information between the host vehicle and a preceding vehicle traveling in front of the host vehicle;
Relative speed calculation means for calculating a relative speed between the host vehicle and the preceding vehicle based on the inter-vehicle distance information detected by the inter-vehicle distance detection means;
Filter means for filtering the relative speed information calculated by the relative speed calculation means;
When the rate of change of the relative speed information or the rate of change of the filtered relative speed information filtered by the filter means is equal to or greater than a predetermined value, 0 is output, and the rate of change of the relative speed information or the post-filter relative Switching means for outputting the post-filter relative speed information when the rate of change of speed information is less than the predetermined value;
A filtered relative speed calculating means for calculating the relative speed based on an output value of the switching means;
Acceleration / deceleration control means for operating the acceleration / deceleration means based on the relative speed calculated by the post-filter relative speed calculation means, wherein the filter means performs filter processing based on the output value of the switching means. An inter-vehicle distance control device. Vehicle speed detection means for detecting the vehicle speed of the host vehicle;
Target inter-vehicle distance setting means for setting a target inter-vehicle distance between the host vehicle and the preceding vehicle;
Target vehicle speed setting means for setting the target speed of the host vehicle based on the vehicle speed detected by the vehicle speed detection means, the target inter-vehicle distance set by the target inter-vehicle distance setting means, and the output value of the switching means; With
The inter-vehicle distance control device according to claim 6, wherein the acceleration / deceleration control means accelerates or decelerates the host vehicle according to the target speed.

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