JP2007210382A - Driving force control device of vehicle - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To obtain a desired vehicle characteristic according to the kind of turning requirement in a vehicle having a driving source of a plurality of motors. <P>SOLUTION: The driving force control device of the vehicle calculates a first target yaw rate and a first vehicle body slide angle to set to a target turning amount based on the steering operation amount (S240) of a driver. When it is determined (S260, S270) that there is turning requirement of the vehicle based on the road condition at the front in the advancing direction of the vehicle, a second target yaw rate and a second target vehicle slide angle are calculated based on the road condition, and the target turning amount is changed (S280) to the second target yaw rate and the second target vehicle body slide angle. Furthermore, the driving force distribution of the front/rear wheels and right/left wheels obtaining the required driving force and the target turning amount is calculated and the torque of the plurality of motors is controlled based on the driving force distribution. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a driving force control apparatus for a vehicle.

  2. Description of the Related Art A vehicle that includes a plurality of motors and can control driving force distribution between front and rear wheels and left and right wheels according to driving conditions is known.

Further, in a vehicle capable of controlling the braking force of each wheel, a technique for calculating a target yaw rate according to the turning characteristics of the vehicle based on the vehicle speed and the steering angle, and controlling the braking force of each wheel so as to realize the target yaw rate. Is described in Patent Document 1.
JP-A-6-24304

  Usually, the turning request of the vehicle is given by the amount of steering operation by the driver, that is, the steering angle. However, recently, an apparatus that detects the presence of an obstacle in front of the vehicle by analyzing an image of a camera mounted on the vehicle, for example, and gives the vehicle a turning request so as to avoid the obstacle is also known. ing.

  In the above-described conventional technology, the target yaw rate is calculated based on the steering angle. Therefore, when there is a turning request from the device using the camera or the like, it is possible to control the driving force distribution of the front and rear wheels and the left and right wheels. Have difficulty.

  An object of the present invention is to realize desired vehicle characteristics in accordance with the type of turning request in a vehicle having a plurality of motors as drive sources.

  The vehicle driving force control apparatus according to the present invention includes a target turning amount calculating means that calculates a first target yaw rate and a first target vehicle body slip angle based on a driver's steering operation amount to obtain a target turning amount of the vehicle. A turn request determination means for determining whether or not there is a turn request for the vehicle based on a road condition ahead of the traveling direction of the vehicle, and when the turn request determination means determines that there is a turn request for the vehicle, The second target yaw rate and the second target vehicle body slip angle are calculated based on the first target yaw rate and the first target vehicle body slip angle, and the target turning amount is determined as the second target yaw rate and the second target vehicle body slip angle. Target turning amount changing means for changing to, driving force distribution calculating means for calculating the driving force distribution of the front and rear wheels and the left and right wheels for realizing the required driving force and the target turning amount, and torques of a plurality of motors based on the driving force distribution Control And a torque control unit for.

  According to the present invention, since the target turning amount is calculated based on the road condition ahead of the traveling direction of the vehicle in addition to the steering operation amount by the driver, the yaw rate and the vehicle body slip angle are controlled for various types of turning requests. And desired vehicle characteristics can be realized.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

(First embodiment)
FIG. 1 shows a configuration diagram of a vehicle in the present embodiment. The power train includes a front wheel driving force transmission path including an engine 1, a clutch 2, a first motor 3, a transmission 6, a reduction gear 7, and a drive wheel 8, a second motor 4, a third motor 5, a reduction gear 9a, 9b and a rear wheel driving force transmission path composed of driving wheels 10a and 10b.

  The driving force of the engine 1 and the first motor 3 is transmitted to the drive wheels 8 via the transmission 6 and the speed reducer 7. The driving force of the second motor 4 is transmitted to the driving wheel 10a via the speed reducer 9a. The driving force of the third motor 5 is transmitted to the driving wheel 10b via the speed reducer 9b.

  The first motor 3 is driven by the electric power stored in the power storage device 11, and is rotated by the output torque of the engine 1 to generate power, and the generated power is stored in the power storage device 11. The second motor 4 and the third motor 5 are driven by at least one of the stored power of the power storage device 11 and the power generated by the first motor 3.

  The engine controller 12 controls the torque of the engine 1 by controlling the throttle opening based on the engine torque command value output from the integrated controller 13. The transmission controller 14 controls the transmission ratio of the transmission 6 based on the transmission ratio command value output from the integrated controller 13. The power storage device controller 18 calculates the SOC by detecting the voltage and current of the power storage device 11 with a voltage sensor and a current sensor. The first motor controller 15, the second motor controller 16, and the third motor controller 17 are based on the first motor torque command value, the second motor torque command value, and the third motor torque command value output from the integrated controller 13. The torques of the first motor 3, the second motor 4, and the third motor 5 are respectively vector controlled.

  The integrated controller 13 includes an SOC calculated by the power storage device controller 18, a vehicle speed calculated from the wheel speed detected by the wheel speed sensor 19, and a steering operation angle δ calculated from the output of the steering angle sensor 20 that detects the steering operation amount. The accelerator pedal operation amount (hereinafter referred to as “APS”) calculated from the output detected by the accelerator pedal operation amount sensor 21 and the image signal supplied from the camera 22 mounted on the vehicle are input.

  Next, control performed by the integrated controller 13 will be described with reference to FIG. FIG. 2 is a flowchart showing the control of the vehicle control apparatus according to the present invention. This control controls the driving force distribution of the front and rear wheels and the left and right wheels so that the fuel consumption is minimized while satisfying the turning amount of the vehicle. This control is repeatedly performed every minute time (for example, 10 ms).

  In step S100 (required driving force calculation means), the driver's required driving force Fsd is calculated based on the vehicle speed VSP and APS.

  In step S200, the target turning amount is calculated based on the vehicle speed VSP, the required driving force Fsd, the steering operation angle, and the image information of the camera 22.

  In step S300 (driving force distribution calculating means), driving force distribution for realizing the target turning amount calculated in step S200 is calculated.

  In step S400 (torque control means), the torque command values of the engine 1, the first motor 3, the second motor 4, and the third motor 5 and the gear ratio command value of the transmission 6 are calculated so as to realize the driving force distribution. .

  Next, the detailed control contents of step S100 will be described according to the flowchart shown in FIG.

  In step S110, APS is read, and in step S120, vehicle speed VSP is read. In step S130, the required driving force Fsd is calculated based on the vehicle speed VSP and APS with reference to the map of FIG. FIG. 4 is a map showing the relationship between the vehicle speed VSP, APS and the driving force. The required driving force Fsd is calculated to be larger as the vehicle speed VSP and APS are larger.

  Next, the detailed control contents of step S200 will be described according to the flowchart shown in FIG.

  In step S210, the vehicle speed VSP is read, in step S220, the required driving force Fsd is read, and in step S230, the steering operation angle δ is read.

  In step S240 (target turning amount calculation means), a target yaw rate tγ and a target vehicle body slip angle tβ, which are target turning amounts, are calculated based on the vehicle speed VSP, the required driving force Fsd, and the steering operation angle δ. The target yaw rate tγ and the target vehicle body slip angle tβ are calculated with reference to a map in which the yaw rate γ_str and the vehicle body slip angle β_str that realize certain turning characteristics are calculated in advance for each vehicle speed VSP, required driving force Fsd, and steering operation angle δ. . Here, the certain turning characteristics are turning characteristics of FF vehicles, turning characteristics of FR vehicles, neutral steer turning characteristics, and the like.

  As an example of the map, the vehicle speed VSP, the required driving force Fsd, and the steering operation angle δ are set to certain values, and the front wheel distribution ratio of the driving force and the left / right driving force difference are changed and distributed to each wheel. Changes in the yaw rate γ and the vehicle slip angle β are shown in the map of FIG.

  The solid line in the figure is a contour line with a constant yaw rate, and tends to increase as the driving force distributed to the rear wheels is larger and the left / right driving force difference is larger. A broken line is a contour line with a constant vehicle body slip angle, and tends to increase as the driving force distributed to the front wheels is larger and the left / right driving force difference is smaller.

  In the figure, the yaw rate γ and the vehicle body slip angle β at the point A are the turning characteristics of the FF vehicle, and the yaw rate γ_str and the vehicle body slip angle β_str at the point A corresponding to changes in the vehicle speed VSP, the required driving force Fsd, and the steering operation angle δ are mapped. By calculating in advance, the target yaw rate tγ and the target vehicle body slip angle tβ that realize the turning characteristics of the FF vehicle are calculated.

  In the present embodiment, the calculation map of the yaw rate γ_str and the vehicle body slip angle β_str is a map obtained by calculating the turning characteristics of the FF vehicle. Can be used.

  In step S250, an image signal supplied from the camera 22 mounted on the vehicle is read.

  In step S260 (obstacle detection means), the image signal is processed to recognize the presence or absence of an obstacle such as a pedestrian or a car. Here, the details of the image processing calculation in this step will be described with reference to the flowchart shown in FIG.

  In step S261, preprocessing is performed on the read image signal to facilitate detection of a target (obstacle) such as a pedestrian or a car. This pre-processing includes an edge extraction process that extracts a high-contrast portion of the image signal, and a particle removal process that removes edge components caused by fine objects on the road from the extracted edge image. is there.

  In step S262, an obstacle present on the road is detected. Since the particles are removed by the preprocessing in step S261, a region having a large number of edge components other than the white line existing in the traveling lane in the image can be recognized as an obstacle. Furthermore, the relative position between the recognized obstacle and the vehicle is also detected.

  In step S263, the presence / absence of the obstacle recognized in step S262 and the positional information relative to the host vehicle are output.

  Returning to FIG. 5, in step S270 (turning request determination means), it is determined whether there is an obstacle around the vehicle based on the information output in step S260. If it is determined that an obstacle exists, the process proceeds to step S280, and if it is determined that no obstacle exists, the process is terminated.

  In step S280 (target turning amount changing means), the target yaw rate tγ and the target vehicle body slip angle tβ are recalculated. First, a yaw rate γ_block that can avoid an obstacle is calculated based on relative position information of the obstacle and the vehicle, the vehicle speed VSP, and the steering operation angle δ, and this is set as a target yaw rate tγ. Next, the vehicle body slip angle β_block at which the tire load factor Li of each wheel after distribution is averaged is calculated from the driving force distribution of the front and rear wheels and the left and right wheels that realize the yaw rate γ_block, and this is calculated as the target vehicle body slip. The angle is tβ.

  Here, a method of calculating β_block will be described using the map of FIG. FIG. 8 shows a case where the vehicle speed VSP, the required driving force Fsd, and the steering operation angle δ are set to certain values, and the front wheel distribution ratio of the driving force and the left / right driving force difference are changed and distributed to each wheel, as in FIG. 2 is an example of a calculation result of changes in the yaw rate γ and the vehicle body slip angle β of the vehicle.

  The above calculation is performed by changing the vehicle speed VSP, the required driving force Fsd, and the steering operation angle δ, and before and after realizing each yaw rate γ and before and after realizing each vehicle body slip angle β, Map calculation is performed in advance on the combination data of the left and right driving force distribution. In addition, the tire load factor Li (i = fr, fl, rr, rl, the same applies hereinafter) of each wheel after distribution is averaged most and the combination data of the front / rear and left / right driving force distribution and each vehicle slip corresponding to the combination The angle data is calculated in advance corresponding to each yaw rate γ. Here, the tire load factor Li of each wheel is calculated according to the following equations (1) to (4).

Lfr = (Fxfr ² + Fyfr ² ) ^1/2 / μ * Wfr (1)
Lfl = (Fxfl ² + Fyfl ² ) ^1/2 / μ * Wfl (2)
Lrr = (Fxrr ² + Fyrr ² ) ^1/2 / μ * Wrr (3)
Lrl = (Fxrl ² + Fyrl ² ) ^1/2 / μ * Wrl (4)
Here, Lfr is the right front tire load factor, Lfl is the left front tire load factor, Lrr is the right rear tire load factor, Lrl is the left rear tire load factor, Fxi is the longitudinal force of each wheel, Fyi is the lateral force, Wi is each wheel The ground load, μ, is the road friction coefficient.

  In the present invention, the following equation (5) is used, and the driving force distribution at which the difference between the maximum value and the minimum value of each tire load factor Li is minimized is the front-rear and left-right drive where each tire load factor Li is most averaged Calculated in advance as a combination of force distribution.

Min [Max (Lfr, Lfl, Lrr, Lrl) −Min (Lfr, Lfl, Lrr, Lrl)] (5)
Also, here, for the calculation of the combination of the front and rear and left and right driving force distribution at which each tire load factor Li is most averaged, the front and rear and right and left driving force distributions that minimize the maximum value of the tire load factor Li of each wheel, each wheel The front and rear and left and right driving force distribution at which the minimum value of the tire load factor Li is maximum may be used, and the front and rear and left and right driving force distribution at which the mean square value of the tire load factor Li of each wheel is minimized.

  Further, since the tire load factor Li depends on the road surface friction coefficient μ, a combination of front and rear and left and right driving force distributions at which the tire load factors Li of the respective wheels are averaged is calculated according to the road surface friction coefficient μ.

  Also, here, if the tire slip angle characteristic is similar to the road surface friction coefficient μ, the tire load factor Li changes according to the change of the road surface friction coefficient μ, but the magnitude relationship of the tire load factor of each wheel is Since there is no change, the tire load factor Li of each wheel may be calculated by setting the road surface friction coefficient μ to 1.

  Next, the detailed control contents of step S300 will be described with reference to the flowchart shown in FIG.

  In step S310, the vehicle speed VSP is read, in step S320, the required driving force Fsd is read, and in step S330, the steering operation angle δ is read.

  In step S340, the target yaw rate tγ and the target vehicle body slip angle tβ calculated in step S200 are read.

  In step S350, the front / rear and left / right driving force distributions for realizing the target yaw rate tγ and the target vehicle body slip angle tβ in the case of the vehicle speed VSP, the required driving force Fsd, and the steering operation angle δ are calculated with reference to the map of FIG. That is, the front / rear and left / right driving force distributions at the point B where the yaw rate γ is the target yaw rate tγ and the vehicle body slip angle β is the target vehicle body slip angle tβ are searched in the map of FIG.

  Next, the detailed control content of step S400 will be described according to the flowchart shown in FIG.

  In step S410, the driving force distribution data calculated in step S350 is read.

  In step S420, motor torque command values for the second motor and the third motor are calculated based on the driving force distribution data read in S401. First, the driving force F_R transmitted to the driving wheel 10a and the driving force F_L transmitted to the driving wheel 10b are calculated based on the rear wheel distribution driving force and the left / right driving force difference. A torque command value tTm2 to be distributed to the second motor 4 is calculated by multiplying the driving force F_R by the tire radius of the driving wheel 10a and further dividing the reduction ratio of the reduction gear 9a. Similarly, the torque command value tTm3 to be distributed to the third motor 5 is calculated by multiplying the driving force F_L by the tire radius of the driving wheel and further dividing the reduction ratio of the reduction gear 9b.

  In step S430, the front wheel distribution driving force of the driving force distribution data read in S410 is multiplied by the tire radius of the driving wheel 8, and the speed ratio of the reduction gear 7 and the speed ratio of the transmission 6 are further divided to determine the torque of the engine 1. Calculates the command value tTe.

  As described above, in the present embodiment, the target turning amount is calculated based on the road condition ahead of the traveling direction of the vehicle in addition to the steering operation amount by the driver. The slip angle β can be controlled and desired vehicle characteristics can be realized.

  Further, the camera 22 acquires image information ahead of the traveling direction of the vehicle and processes the image signal to recognize the presence or absence of an obstacle such as a pedestrian or a car and the relative position between the vehicle and the obstacle. Therefore, the target yaw rate tγ and the target vehicle body slip angle tβ can be calculated more accurately so that the obstacle can be avoided.

  Further, when it is determined that there is an obstacle, the vehicle body slip angle β_block at which the tire load factor Li of each wheel after distribution is most averaged from among the driving force distribution of the front and rear wheels and the left and right wheels that realizes the yaw rate γ_block Since this is used as the target vehicle body slip angle tβ, the stability of the vehicle behavior can be ensured particularly when the turning demand is large.

(Second Embodiment)
In the present embodiment, the overall configuration of the vehicle is the same as that of the first embodiment, and part of the calculation control of the target turning amount corresponding to step S200 of the first embodiment is different. Hereinafter, the calculation control of the target turning amount in the present embodiment will be described with reference to the flowchart of FIG. Note that the same components as those in the first embodiment are denoted by the same reference numerals, and description thereof is omitted as appropriate.

  Steps S1210 to S1250 are the same as those in the first embodiment.

  In step S1260 (lane departure detection means), the image signal is processed to recognize information on the center line and the white line that divides the travel lane in which the vehicle travels. Here, the details of the image processing calculation in this step will be described with reference to the flowchart shown in FIG.

  In step S1261, preprocessing is performed to make it easier to detect the center line and the white line on the read image signal. Similar to step S261, this preprocessing is an edge extraction process for extracting a high contrast portion of the image signal, and for removing edge components caused by fine objects on the road from the extracted edge image. For example, a particle removal process.

  In step S1262, a white line is detected from the preprocessed image, and the relative position in the left-right direction of the vehicle with respect to the white line is recognized based on the detected white line information.

  In step S1263, the relative position information of the vehicle with respect to the white line recognized in step S1262 is output.

  Returning to FIG. 11, in step S1270, it is determined whether or not the vehicle deviates from the lane based on the information calculated in step S1260. If it is determined that the vehicle has deviated from the lane, the process proceeds to step S1280. If it is determined that the vehicle has not deviated, the process is terminated.

  In step S1280, the target yaw rate tγ and the target vehicle body slip angle tβ are recalculated. First, the yaw rate γ_delta for correcting the deviation amount is calculated based on the deviation amount in the left-right direction of the vehicle with respect to the white line, the vehicle speed VSP, and the steering operation angle δ. A value γ_lane obtained by adding the yaw rate γ_delta to the yaw rate γ_str calculated in step S1240 is set as the target yaw rate tγ.

  Next, among the front / rear and left / right driving force distributions for realizing the yaw rate γ_lane, the front / rear driving force distribution rate becomes the same as the front / rear driving force distribution rate for realizing the yaw rate γ_str and the vehicle body slip angle β_str calculated in step S1240. The distributed vehicle slip angle data is read with reference to the map of FIG. 13, and the vehicle slip angle β_lane is set as the target vehicle slip angle tβ.

  Thereafter, as in the first embodiment, the front / rear and left / right driving force distributions are calculated so as to realize the target yaw rate tγ and the target vehicle body slip angle tβ, and the torques of the motors 3 to 5 and the engine 1 and the transmission gear ratio of the transmission 6 are calculated. To control.

  As described above, in this embodiment, the camera 22 acquires image information in front of the vehicle in the traveling direction, processes the image signal to detect a white line, and based on the detected white line information, the vehicle in the left-right direction of the vehicle is detected. Since the relative position is recognized, the target yaw rate tγ and the target vehicle body slip angle tβ can be calculated more accurately so that the vehicle does not depart from the lane.

  Further, when it is determined that the vehicle deviates from the lane, the yaw rate γ_str and the vehicle body slip angle β_str calculated in step S1240 are calculated from the front / rear and left / right driving force distributions that realize the yaw rate γ_lane. Since the vehicle body sliding angle β_lane of the driving force distribution that is the same as the realized front / rear driving force distribution rate is set as the target vehicle body sliding angle tβ, it is possible to reduce the driver's uncomfortable feeling due to a change in the turning characteristics of the vehicle.

  The present invention is not limited to the embodiment described above, and various modifications and changes can be made within the scope of the technical idea.

1 is an overall configuration diagram showing a driving force control apparatus for a vehicle in the present embodiment. It is a flowchart which shows control of the driving force control apparatus of the vehicle in this embodiment. It is a flowchart which shows the calculation control of the request | requirement driving force Fsd. It is a map which shows the relationship between vehicle speed VSP, an accelerator opening, and the request | requirement driving force Fsd. It is a flowchart which shows the calculation control of the target turning amount. It is a map which shows the relationship between driving force distribution and vehicle behavior. It is a flowchart which shows the arithmetic control of image processing. It is the map explaining the calculation method of a vehicle body slip angle. It is a flowchart which shows the calculation control of driving force distribution. It is a flowchart which shows the calculation control of each command value. It is a flowchart which shows the calculation control of the target turning amount in 2nd Embodiment. It is a flowchart which shows the calculation control of the image process in 2nd Embodiment. It is the map explaining the calculation method of a vehicle body slip angle.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Engine 2 Clutch 3 1st motor 4 2nd motor 5 3rd motor 6 Transmission 7 Deceleration device 8 Drive wheel 9a Deceleration device 9b Deceleration device 10a Drive wheel 10b Drive wheel 11 Power storage device 12 Engine controller 13 Integrated controller 14 Transmission controller 15 First motor controller 16 Second motor controller 17 Third motor controller 18 Power storage device controller 19 Wheel speed sensor 20 Steering angle sensor 21 Accelerator pedal operation amount sensor 22 Camera

Claims (5)

In a vehicle driving force control apparatus capable of controlling the driving force distribution of front and rear wheels and left and right wheels of a vehicle by a plurality of motors,
Required driving force calculating means for calculating a driver's required driving force;
A target turning amount calculating means for calculating a first target yaw rate and a first target vehicle body slip angle based on a driver's steering operation amount and setting the target turning amount of the vehicle;
A turn request determination means for determining whether or not there is a turn request for the vehicle based on a road condition ahead of the traveling direction of the vehicle;
When it is determined by the turning request determining means that there is a turning request for the vehicle, a second target yaw rate and a second target yaw rate are determined based on the road condition, the first target yaw rate, and the first target vehicle body slip angle. A target turning amount changing means for calculating a target vehicle body sliding angle and changing the target turning amount to the second target yaw rate and the second target vehicle body sliding angle;
Driving force distribution calculating means for calculating the driving force distribution of the front and rear wheels and the left and right wheels for realizing the required driving force and the target turning amount;
Torque control means for controlling torque of the plurality of motors based on the driving force distribution;
A driving force control apparatus for a vehicle, comprising: It further comprises obstacle detection means for acquiring image information ahead of the vehicle in the traveling direction, detecting an obstacle based on the image information, and calculating a distance from the obstacle,
2. The driving force control apparatus for a vehicle according to claim 1, wherein the turning request determining means determines that there is a turning request for the vehicle when the obstacle is detected. Lane departure detection means for obtaining image information ahead of the vehicle in the traveling direction and detecting that the vehicle deviates from the lane of the road based on the image information;
The vehicle driving force control device according to claim 1, wherein the turning request determination unit determines that there is a turning request for the vehicle when a lane departure by the vehicle is detected.   The target turning amount changing means is configured to average the tire load factor of each wheel of the vehicle body when the turning request determining means determines that there is a turning request for the vehicle. The vehicle driving force control apparatus according to claim 2, wherein:   The target turning amount changing means is configured to realize the second target yaw rate while realizing the second target yaw rate when the turning request determining means determines that there is a turning request for the vehicle. The vehicle driving force control apparatus according to claim 3, wherein the second vehicle body slip angle is calculated so as to realize an angle.