JP3901024B2 - Travel control device - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a travel control device that detects a preceding vehicle and performs follow-up travel while controlling the distance between vehicles.
[0002]
[Prior art]
2. Description of the Related Art A travel control device that detects a preceding vehicle using a camera, a radar, or the like and controls the distance from the preceding vehicle while following the vehicle is known. In such a traveling control device, when the preceding vehicle changes the traveling state, a delay is likely to occur when the traveling state of the host vehicle is followed, and the followability is likely to deteriorate. The technique disclosed in Japanese Utility Model Laid-Open No. 2-133800 is an example of a technique for improving the followability of the host vehicle, and changes the target inter-vehicle distance according to the acceleration / deceleration of the preceding vehicle. As a result, followability and safety are improved.
[0003]
[Problems to be solved by the invention]
However, in this technique, control is performed so as to maintain the target inter-vehicle distance. Therefore, even when the preceding vehicle is decelerating, if the inter-vehicle distance is too wide, the host vehicle is accelerated and the inter-vehicle distance is approaching. In some cases, even when the acceleration of the preceding vehicle is large, the vehicle is decelerated and the control does not match the driver's feeling, which may make the driver feel uncomfortable.
[0004]
Then, this invention makes it a subject to provide the traveling control apparatus which improved followability by control corresponding to a driver | operator's sense.
[0005]
[Means for Solving the Problems]
In order to solve the above problems, a travel control device according to the present invention is a travel control device that detects a preceding vehicle and controls an inter-vehicle distance, based on the inter-vehicle distance, relative speed, and own vehicle speed between the preceding vehicle and the own vehicle. The target inter-vehicle distance and the target acceleration / deceleration state of the host vehicle are calculated, and the target inter-vehicle distance and the target acceleration / deceleration state are adjusted according to the preceding vehicle or the acceleration / deceleration state of the host vehicle, and the relative speed Vr between the preceding vehicle and the host vehicle is determined. In a plane coordinate system using (developed vehicle speed V _M -preceding vehicle speed V _P ) and deviation ΔD between the distance between the preceding vehicle and the own vehicle and the target inter-vehicle distance as parameters, the point (Vr, ΔD) is When the deviation ΔD <0, the relative speed Vr is equal to or less than a predetermined negative value. When the deviation ΔD ≧ 0, the relative speed Vr is proportional to the magnitude of the deviation ΔD. In the region that is less than or equal to the value that increases in the negative direction At some point, it is determined that the preceding vehicle is decelerating, and even if the inter-vehicle distance from the preceding vehicle is greater than the target inter-vehicle distance, the vehicle is decelerating at a deceleration that can approach the inter-vehicle distance with the preceding vehicle while decelerating. It is characterized by performing deceleration.
[0006]
The target inter-vehicle distance and the target acceleration / deceleration state are set according to the inter-vehicle distance, relative speed, and own vehicle speed between the preceding vehicle and the own vehicle, and the target inter-vehicle distance and the acceleration / deceleration state are set according to the acceleration / deceleration state of the preceding vehicle or the own vehicle. By performing the adjustment, fine control that matches the driver's feeling can be performed.
[0007]
Even if the inter-vehicle distance from the preceding vehicle is greater than the target inter-vehicle distance, if deceleration of the preceding vehicle is detected, slow deceleration is performed. By performing slow deceleration, while maintaining a gentle approach to the preceding vehicle, it suppresses inadvertent acceleration and matches the driver's feeling to continue the transition to the target inter-vehicle distance.
[0010]
DETAILED DESCRIPTION OF THE INVENTION
DESCRIPTION OF EXEMPLARY EMBODIMENTS Hereinafter, preferred embodiments of the invention will be described in detail with reference to the accompanying drawings. In order to facilitate the understanding of the description, the same reference numerals are given to the same components in the drawings as much as possible, and duplicate descriptions are omitted.
[0011]
FIG. 1 is a schematic diagram of a vehicle equipped with a travel control device according to the present invention, and FIG. 2 is a block diagram of the vehicle. In the traveling control device 60, a laser radar sensor 1 that irradiates a laser beam forward as a means for detecting a preceding vehicle and detects the reflected light is disposed at the front of the vehicle. The detection of the preceding vehicle and the traveling control of the vehicle are performed by the control ECU 2. The control ECU 2 includes an inter-vehicle control ECU 20, an engine ECU 21, and a brake ECU 22.
[0012]
Among these, the engine ECU 21 controls the operation of the engine 3, and the control includes the operation control of the throttle motor 31 of the electronically controlled throttle. The brake ECU 22 controls the operation of the brakes disposed on each wheel, and the braking force of each brake is controlled by controlling the hydraulic pressure applied by the brake actuator 4.
[0013]
The ECU 2 includes a wheel speed sensor 50 that detects the wheel speed of each wheel, a hydraulic sensor 51 that detects the hydraulic pressure applied to each brake, a G sensor 52 that detects vehicle longitudinal acceleration, and a throttle opening. Each output of the throttle opening sensor 53 and the output signal of the laser radar sensor 1 described above are input.
[0014]
Next, the operation of the travel control device 60 will be described. FIG. 3 is a diagram illustrating states of the preceding vehicle and the host vehicle. As shown in the figure, the preceding vehicle is represented by P and the host vehicle is represented by M. This control turns off the system when the preceding vehicle P does not exist. Note that steady running may be performed at a predetermined speed. On the other hand, when the preceding vehicle P exists, the vehicle travels while maintaining the inter-vehicle distance. The inter-vehicle distance Dr with the host vehicle is made to coincide with the target distance Dt, and the relative speed Vr (the vehicle speed V _M of the host vehicle _{M is set).} -Control is performed so that the vehicle speed _VP ) of the preceding vehicle P becomes zero.
[0015]
4 to 8 are flowcharts of specific control. The following control is performed in the ECU 2, more specifically, the inter-vehicle distance control ECU 20, the engine ECU 21, and the brake ECU 22 in cooperation. Repeatedly executed. The follow-up running mode is released when the driver operates a brake pedal, an accelerator pedal, a shift lever, or the like in addition to switching a control switch (not shown) to OFF.
[0016]
First, the main process shown in FIG. 4 will be described. In step S1, outputs of the laser radar sensor 1, the wheel speed sensor 50, the hydraulic pressure sensor 51, the G sensor 52, and the throttle opening degree sensor 53 are read. In step S2, based on the loaded output value to calculate a vehicle speed V _M brake ECU22 from the output value of the wheel speed sensor 50, vehicle control ECU20 is to determine whether the preceding vehicle P, there is the preceding vehicle P If it is, the inter-vehicle distance Dr with the preceding vehicle P and the relative speed Vr and the relative acceleration Gr of the host vehicle M with the preceding vehicle P are calculated.
[0017]
In step S3, a target acceleration Gt of the host vehicle M for performing the follow-up control is calculated. FIG. 5 is a flowchart showing details of the Gt calculation. First, in step S21, a base inter-vehicle time Δtb is set. Here, the base inter-vehicle time Δtb corresponds to the base inter-vehicle distance, and means that the host vehicle M reaches the position of the preceding vehicle P after Δtb when traveling at the current speed. Is set by In addition, when using constant speed driving, the driver sets the set vehicle speed, and this base inter-vehicle time Δtb is set by the inter-vehicle control ECU 20 based on the set vehicle speed, the actual inter-vehicle distance, and the actual vehicle speed VM. The
[0018]
In step S22, the target acceleration value Gtold set in the previous time step is compared with the threshold value Gth2. If Gtold is less than or equal to Gth2, the process proceeds to step S23, and this time Gtold is compared with -Gth2. If Gtold is greater than or equal to -Gth2, the process proceeds to step S24, where it is determined whether or not the previously set fluctuation inter-vehicle time Δtf is positive. This fluctuation inter-vehicle time Δtf is an adjustment amount for increasing or decreasing the inter-vehicle time with respect to the base inter-vehicle time Δtb according to the acceleration / deceleration state of the preceding vehicle P or the host vehicle M. If the fluctuation inter-vehicle time Δtf is not positive, the process proceeds to step S25 to determine whether or not the fluctuation inter-vehicle time Δtf is negative. When the fluctuation inter-vehicle time Δtf is 0, the process directly proceeds to step S26, and the sum of the base inter-vehicle time Δtb and the fluctuation inter-vehicle time Δtf is set as the target inter-vehicle time Δtx. When Δtf is 0, Δtx = Δtb. In step S27, the target inter-vehicle distance Dt is obtained from the value of the target inter-vehicle time Δtx. In step S28, the target acceleration Gt is calculated from the deviation ΔD between the target inter-vehicle distance Dt and the current inter-vehicle distance Dr and the relative speed Vr. This Gt value may be stored as a map value for ΔD and Vr. Gt takes a large value when the absolute value of the relative velocity Vr and the absolute value of the deviation ΔD are large.
[0019]
If it is determined in step S22 that Gtold exceeds Gth2, and if Δtf is positive in step S24, the process proceeds to step S30, and Δtf is decreased by a predetermined value Δtfx. Subsequently, in step S31, when Δtf thus obtained is lower than Δtfmin, Δtf is set to Δtfmin (a predetermined negative value) and the lower limit value is guarded to Δtfmin. Thereafter, the process proceeds to step S26, the target inter-vehicle time Δtx is set, the target inter-vehicle distance Dt is obtained (step S27), and the target acceleration Gt is calculated (step S28).
[0020]
If it is determined in step S23 that Gtold is less than -Gth2, or if Δtf is negative in step S25, the process proceeds to step S35, and Δtf is increased by a predetermined value Δtfx. In step S36, when Δtf thus obtained exceeds Δtfmax, Δtf is set to Δtfmax (a predetermined positive value), and the upper limit value is guarded to Δtfmax. Thereafter, the process proceeds to step S26, the target inter-vehicle time Δtx is set, the target inter-vehicle distance Dt is obtained (step S27), and the target acceleration Gt is calculated (step S28).
[0021]
When the vehicle is accelerating, the target inter-vehicle distance is set to be short. Conversely, when the vehicle is decelerating, the inter-vehicle control can be performed in accordance with the driver's feeling by taking a long target inter-vehicle distance. And sudden acceleration and sudden deceleration at the start of acceleration / deceleration are suppressed. Further, the process of step S24 → 30 → 31 and S25 → 35 → 36, the hunting of the vehicle speed V _M of the acceleration and deceleration end is suppressed.
[0022]
When Gt is calculated in this way, the process proceeds to step S4 shown in FIG. 4, and it is determined whether or not Vr and ΔD are within the predetermined area A shown in FIG. If it is within the predetermined area A, it is determined that the preceding vehicle P is decelerating. If it is determined that the preceding vehicle P is not decelerating, the process proceeds to step S5, and the relative acceleration Gr is compared with a predetermined threshold value Gth1 (which is a negative value). If the relative acceleration Gr is greater than or equal Gth1, the process proceeds to step S6, and compares the relative speed Vr and the vehicle speed V _M of the function value f (V _M). For example, f (V _M) = - a _{a × V M + b, a} , b is a both positive constant, positive at the time of low-speed vehicle speed V _M is less than b / a, negative at high speeds in excess of b / a Takes the value of When Vr is equal to or greater than f (V _M ), the process proceeds to step S7. That is, the preceding vehicle P is not decelerating in (step S4), and the relative acceleration Gr is Gth1 more (step S5), and if the relative vehicle speed Vr is f (V _M) above (step S6), the control acceleration Gcon The value of Gt set in step S3 is set as it is, and the process proceeds to step S8 to perform acceleration control.
[0023]
If the preceding vehicle P is determined to be decelerating at step S4, [Delta] D in Kan'no control acceleration Gs and proceeds to step S10, it sets the negative acceleration G _A obtained from Vr. If it is determined in step S5 that the relative acceleration Gr is less than Gth1 (in this case, the relative speed Vr is being decelerated, that is, the deceleration of the host vehicle M is greater than the preceding vehicle P or the preceding vehicle P is accelerated) when the acceleration greater than), the process proceeds to step S11 to set the predetermined negative acceleration G _B to Kan'no control acceleration Gs (where a G _a> G _B). When the relative speed Vr is smaller than f (V _M) in step S6, the operation proceeds to step S12 to set the predetermined negative acceleration G _C in Kan'no control acceleration Gs by (wherein, G _A ≧ G _C> is a G _B).
[0024]
After setting Gs, the process proceeds to step S13, and Gs correction calculation is performed. Specifically, if the state continues for a predetermined time or longer after the transition from steps S10 to S12, Gs is decreased by a predetermined value ΔGs. In step S14, Gt set in step S3 is compared with Gs set in this way. If Gs is equal to or greater than Gt, priority is given to Gt, the process proceeds to step S7, the value of Gt set in step S3 is set as it is as the value of control acceleration Gcon, and the process proceeds to step S8 to accelerate. Take control.
[0025]
On the other hand, when Gs is less than Gt, priority is given to Gs, the process proceeds to step S15, the value of Gs is set as the value of control acceleration Gcon, and the process proceeds to step S8 to perform acceleration control.
[0026]
As a result, when the preceding vehicle P is decelerating, it is possible to perform control that gives the driver a sense of security by performing slow deceleration even when there is a margin in the inter-vehicle distance. If priority is given to maintaining the inter-vehicle distance, the control will accelerate and decelerate after matching the inter-vehicle distance to the target inter-vehicle distance, and maintain the relative speed, but by performing a slow deceleration as in this control, By decelerating and approaching the inter-vehicle distance, acceleration is not wasted, which is effective in terms of fuel consumption, and also matches the driver's sensitivity.
[0027]
Further, when the relative acceleration Gr is less than a predetermined negative value, when the relative speed Vr with the preceding vehicle P is decelerating, when the relative speed is smaller than a predetermined value (when the speed of the host vehicle M is high). Takes a negative value.) In order to suppress unnecessary acceleration, the vehicle is controlled to match the driver's sensitivity.
[0028]
6 to 8 are actual flowcharts of the acceleration control. FIG. 6 is a flowchart of the main process, and FIGS. 7 and 8 are flowcharts showing the processes of the switching determination 1 and the switching determination 2, respectively.
[0029]
In step S41, it is determined whether or not the throttle opening θ is positive, that is, whether or not the throttle opening control is being performed. When θ is positive, that is, when throttle opening control is being performed, the routine proceeds to switching determination 1 in step S48 described later, and when θ is 0, that is, when throttle opening control is not being performed, the routine proceeds to step S42. In step S42, it is determined whether or not the brake oil pressure Pb detected by the oil pressure sensor 51 exceeds a predetermined value P0, that is, whether or not braking control is being performed. When Pb exceeds P0, that is, during braking control, the routine proceeds to switching determination 2 in step S49 described later. On the other hand, when Pb is equal to or less than P0, that is, when braking control is not being performed, the process proceeds to step S43, and the values of the braking control counter ib and the throttle control counter it are reset to 0, respectively. In step S44, the value of the control acceleration Gcon is compared with a predetermined threshold value Gth4. This Gth4 takes a predetermined negative value. If Gcon exceeds Gth4, it is determined that it is necessary to perform throttle control, the process proceeds to step S45, the throttle opening θt is increased by Δθt, and the target brake control hydraulic pressure Pt is set to the hydraulic pressure P0 during non-braking. Set to. In the subsequent step S46, the operations of the throttle motor 31 and the brake actuator 4 are controlled according to the obtained θt and Pt, and the process is terminated.
[0030]
In step S44, if Gcon is equal to or less than Gth4, it is determined that it is necessary to perform braking control. The process proceeds to step S47, where the brake control hydraulic pressure Pt is increased by ΔPt, and the target throttle opening θt is fully closed. A certain 0 is set, and the process proceeds to step S46 to perform operation control.
[0031]
In switching determination 1 in step S48, first, the value of the braking control counter ib is reset to 0 (step S51). Subsequently, the value of Gcon is compared with a threshold value Gth3 (step S52). This Gth3 takes a negative value. If GCON is more Gth3, by comparing the the G _M -G1 minus the contribution G1 of the acceleration obtained by controlling the throttle from the acceleration G _M of the vehicle (θ) (θ) Gcon Then, it is determined whether or not Gcon exists within the acceleration range obtained only by the throttle control (step S53). Here, G1 (θ) is an estimated value considering a downhill case. If G _M -G1 (θ) exceeds Gcon, it is determined that there is such a possibility, and the value of the throttle control counter it is incremented by 1 (step S54). In step S55, it is determined whether or not the value of it exceeds the threshold value itth. If it is determined that it is less than itth, the routine proceeds to step S56, where the throttle control is continued, the target throttle opening degree θt is increased or decreased according to the deviation between Gcon and Gr, and the target brake hydraulic pressure Pt remains at P0. maintain. If it is determined that it is equal to or greater than itth, the target acceleration cannot be achieved by continuing the throttle control. Therefore, the process proceeds to step S57 where the target throttle opening θt is set to 0 and the target brake hydraulic pressure Pt is set to P0 + ΔPt. Set to, and shift to brake control.
[0032]
If it is determined in step S53 that G _M -G1 (θ) is equal to or less than Gcon, it is determined that Gcon can be achieved only by throttle control, it is reset to 0 (step S58), and the process proceeds to step S56. And the throttle control amount θt is set.
[0033]
If it is determined in step S52 that Gcon is equal to or less than Gth3, it is determined that the target acceleration (actually a deceleration command) cannot be achieved by throttle control, and the process proceeds to step S59. it was, first reset it to zero, comparing the vehicle acceleration G contribution of the acceleration obtained by controlling the throttle G2 from _M (theta) minus G _M -G2 and (theta) GCON Thus, it is determined whether or not Gcon can be achieved with the deceleration obtained when the throttle is fully closed (step S60). Here, G2 (θ) is an estimated value considering a flat road, and takes a value smaller than G1 (θ).
[0034]
If G _M -G2 (θ) exceeds Gcon, it is determined that the throttle control cannot achieve the control acceleration Gcon, which is a deceleration command, and the routine proceeds to step S57 and the target throttle opening θt. Is set to 0, the target brake hydraulic pressure Pt is set to P0 + ΔPt, and the process proceeds to the brake control. On the other hand, if G _M -G2 (θ) is equal to or less than Gcon, it is determined that there is a possibility that the control acceleration Gcon, which is a deceleration command, can be achieved by the throttle control, and the routine proceeds to step S56 to control the throttle control amount θt. Set up.
[0035]
In the switching determination 2 in step S49, first, the value of the throttle control counter it is reset to 0 (step S71). Subsequently, the value of Gcon is compared with a threshold value Gth3 (step S72). This Gth3 is the same as the value used in step S52 described above. If Gcon is Gth3 below, G _M obtained by subtracting the contribution G3 (Pb) of the acceleration obtained by the brake control from the acceleration G _M of the vehicle (actually takes a negative value because it is the deceleration) - By comparing G3 (Pb) and Gcon, it is determined whether or not Gcon exists within the deceleration adjustment range based only on the brake control (step S73). Here, G3 (Pb) is an estimated value considering an uphill case. If G _M -G3 (Pb) is less than Gcon, it is determined that there is a possibility that the deceleration adjustment range is not satisfied, and the value of the braking control counter ib is incremented by 1 (step S74). In step S75, it is determined whether or not the value of ib exceeds the threshold value ibth. If it is determined that ib is less than ibth, the routine proceeds to step S76, where brake control is continued, the target brake hydraulic pressure Pt is increased or decreased according to the deviation between Gcon and Gr, and the target throttle opening θt remains zero. maintain. If it is determined that ib is equal to or greater than ibth, the target acceleration cannot be achieved by continuing the brake control. Therefore, the process proceeds to step S77 where the target brake hydraulic pressure Pt is set to 0 and the target throttle opening degree θt is set to Δθt. To shift to throttle control.
[0036]
If it is determined in step S73 that G _M -G3 (Pb) is equal to or less than Gcon, it is determined that Gcon can be achieved only by brake control, ib is reset to 0 (step S78), and the process proceeds to step S76. And the target brake oil pressure Pt is set.
[0037]
If it is determined in step S72 that Gcon exceeds Gth3, it is likely that the target acceleration cannot be achieved by brake control compared to other cases, and the process proceeds to step S79. reset to the own vehicle G _M -G4 from the acceleration G _M obtained by subtracting the contribution G4 (Pb) of the acceleration obtained by the brake control and (Pb) by comparing the GCON, the deceleration adjustment range of the brake Whether or not Gcon exists is determined (step S80). Here, G4 (Pb) is an estimated value considering a flat road, and has a relationship of 0> G4 (Pb)> G3 (Pb).
[0038]
If G _M -G4 (Pb) is less than Gcon, the brake control is determined to be a case where the control acceleration Gcon can not be achieved, and the target throttle opening θt to Δθt and proceeds to step S77, the target The brake hydraulic pressure Pt is set to P0, and the process proceeds to throttle control. On the other hand, when G _M -G4 (Pb) is equal to or greater than Gcon, it is determined that there is a possibility that the control acceleration Gcon can be achieved by the brake control, and the process proceeds to step S76 to set the brake control amount Pt. .
[0039]
By performing the switching control as described above, it is possible to quickly switch between the brake and the throttle control, and in particular, it is possible to suppress the occurrence of control hunting caused by the switching delay when climbing or descending. it can.
[0040]
In the above description, the example in which the deceleration of the preceding vehicle P is determined by the map has been described. However, for example, it may be determined from the acceleration of the preceding vehicle P itself, or the brake lamp and the hazard lamp of the preceding vehicle P may be turned on. It may be determined and detected by an image input means or an optical sensor.
[0041]
【The invention's effect】
As described above, according to the present invention, not only the inter-vehicle distance between the preceding vehicle and the host vehicle but also the acceleration / deceleration state of the host vehicle is adjusted according to the acceleration / deceleration state, thereby matching the driver's sensitivity. Travel control can be performed.
[Brief description of the drawings]
FIG. 1 is a schematic view of a vehicle equipped with a travel control apparatus according to the present invention.
FIG. 2 is a block diagram of FIG.
FIG. 3 is a diagram showing a state of a preceding vehicle and a host vehicle.
4 is a flowchart showing a main process of control of the apparatus of FIG.
FIG. 5 is a flowchart showing details of target acceleration calculation in FIG. 4;
6 is a flowchart of a main process of acceleration control in FIG.
7 is a flowchart showing processing of switching determination 1 in FIG. 6;
FIG. 8 is a flowchart showing processing of switching determination 2 in FIG. 6;
FIG. 9 is an area map used for a preceding vehicle deceleration determination.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 ... Laser radar sensor, 2 ... Control ECU, 3 ... Engine, 4 ... Brake actuator, 20 ... Inter-vehicle control ECU, 21 ... Engine ECU, 22 ... Brake ECU, 31 ... Throttle motor, 50 ... Wheel speed sensor, 51 ... Oil pressure sensor, 52 ... G sensor, 53 ... throttle opening sensor, 60 ... running control device, P ... preceding vehicle, M ... own vehicle.

Claims (1)

In the travel control device that detects the preceding vehicle and controls the inter-vehicle distance,
The target inter-vehicle distance and the target acceleration / deceleration state of the host vehicle are calculated based on the inter-vehicle distance, relative speed, and host vehicle speed between the preceding vehicle and the host vehicle, and the target inter-vehicle distance according to the preceding vehicle or the acceleration / deceleration state of the host vehicle. And the target acceleration / deceleration state is adjusted ,
A plane in which the relative speed Vr between the preceding vehicle and the host vehicle (vehicle speed V _M of the host vehicle−vehicle speed V _P of the preceding vehicle) and the deviation ΔD between the inter-vehicle distance between the preceding vehicle and the host vehicle and the target inter-vehicle distance are parameters. In the coordinate system, the point (Vr, ΔD) is
When the deviation ΔD <0, the relative speed Vr is equal to or less than a predetermined negative value,
When the deviation ΔD ≧ 0, the relative speed Vr is equal to or less than a value at which the difference from the negative predetermined value increases in the negative direction in proportion to the magnitude of the deviation ΔD.
It is determined that the preceding vehicle is decelerating when it is within the area, and even if the inter-vehicle distance from the preceding vehicle is farther than the target inter-vehicle distance, the inter-vehicle distance from the preceding vehicle can be reduced while decelerating. A travel control device characterized by slow deceleration at a speed .

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