Vehicle control device

Abstract

To provide a technique for suppressing an imbalance in driving force.SOLUTION: A vehicle control device comprises at least one processor and controls a plurality of motors, each connected to one of two or more drive wheels provided on a vehicle based on a speed command. The processor calculates a difference in driving force between the plurality of motors and calculates a correction amount for adjusting a value of the speed command so that the difference of a ratio of the driving force matches a specific target value.SELECTED DRAWING: Figure 3

Description

Technical Field

[0001] The present disclosure relates to a vehicle control device.

Background Art

[0002] When controlling a plurality of motors respectively connected to two or more drive wheels provided on a vehicle according to a speed command, since the ground speeds of the respective drive wheels during vehicle turning are different, if the same target speed is set for each motor, an imbalance in driving force may occur. Specifically, when the differential (differential gear) between the front wheels or the rear wheels is locked, circulating torque is generated between the left and right wheels during turning, and when the center differential of an all-wheel drive vehicle is locked, circulating torque is generated between the front and rear wheels during turning. The same thing can occur electrically. To prevent circulating torque, the prior art disclosed in Patent Document 1 corrects the target speed of each drive wheel, that is, the target motor rotation speed, according to the steering angle, and sets the target speed of the inner drive wheel to the value obtained by multiplying the target speed of the outer drive wheel by "inner drive wheel turning radius / outer drive wheel turning radius", thereby suppressing tire bulging, dragging, etc. caused by circulating torque.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] Here, when the tire air pressure of one of the plurality of drive wheels decreases, only the tire effective diameter of the drive wheel becomes smaller. Therefore, even when the vehicle is in a straight-ahead state, it is necessary to make the rotational speed of the drive wheel higher than the rotational speeds of the other drive wheels. However, in the control of the prior art, in the situation where the vehicle is actually moving straight, since the target rotational speeds of the motors connected to the plurality of drive wheels are the same, the drive wheel becomes regenerative, and in order to maintain the vehicle speed, the driving force (that is, the driving torque) of the other drive wheels increases, resulting in an imbalance in the driving force. Thus, in the prior art, there is room for improvement in suppressing the imbalance in the driving force.

[0005] The present disclosure provides a technique for suppressing an imbalance in driving force.

Means for Solving the Problems

[0006] According to one aspect of the present disclosure, there is provided a vehicle control device including at least one processor and configured to control a plurality of motors respectively connected to two or more drive wheels provided in a vehicle according to a speed command. The processor calculates a difference in driving force of each of the plurality of motors, and calculates a correction amount for correcting the value of the speed command so that the difference or ratio of the driving forces matches a specific target value.

Effects of the Invention

[0007] According to the present disclosure, an imbalance in driving force can be suppressed.

Brief Description of the Drawings

[0008]

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[0009] Hereinafter, one aspect of the present disclosure will be described with reference to the drawings. Note that the drawings used in the following description are all schematic, and the dimensional relationships and ratios of the respective elements shown in the drawings do not necessarily match the actual ones. Further, the present disclosure is not limited to the following embodiments, and can be implemented with appropriate modifications within the scope of the present disclosure.

[0010] FIG. 1 is a configuration diagram of a vehicle including a vehicle control device according to an embodiment of the present disclosure. The vehicle 100 may be interpreted as a battery electric vehicle (BEV) having a battery 101 that stores electric power for traveling and a plurality of motors 102 that are main motors for traveling as power sources. Note that the vehicle 100 is not limited to a BEV and may include a hybrid electric vehicle (HEV) equipped with the battery 101, a plug-in hybrid electric vehicle (PHEV), and the like.

[0011] The vehicle 100 may include a battery 101, a plurality of motors 102, a plurality of inverters 103, and a vehicle control device 104.

[0012] The battery 101 may be interpreted as a power storage device including a plurality of cells. The battery 101 may store electric power for driving the motor 102 and may also store electric power regenerated from the motor 102.

[0013] The motor 102 may be interpreted as a main motor for vehicle travel. The motor 102 may rotate by alternating current power from the inverter 103 to apply a driving torque to the drive wheels 1 of the vehicle 100 to cause the vehicle 100 to travel. Hereinafter, the motor 102 may be referred to as an MG (Motor Generator). For example, of the two drive wheels 1 (rear wheels) provided at the rear of the vehicle 100, the motor 102 (MGRL) connected to the left wheel may apply a driving torque to the left wheel, and the motor 102 (MGRR) connected to the right wheel may apply a driving torque to the right wheel. The vehicle 100 of the present disclosure may include a plurality of motors 102 respectively connected to two or more drive wheels 1.

[0014] The inverter 103 may be interpreted as a drive device that drives the motor 102 by being controlled by the vehicle control device 104. The inverter 103 may drive the motor 102 by converting the DC power discharged from the battery 101 into AC power and supplying the AC power to the motor 102. The inverter 103 may have a function of charging the battery 101 by converting the AC power regenerated from the motor 102 into DC power and supplying the DC power to the battery 101. The inverter L, which is the inverter 103 for the left wheel, and the inverter R, which is the inverter 103 for the right wheel, are controlled by the vehicle control device 104.

[0015] The vehicle control device 104 may be interpreted as a device that controls a plurality of motors 102 according to a speed command based on information from a sensor group. The sensor group may include an accelerator sensor 2, a steering angle sensor 3, a plurality of rotation sensors 4, and the like. The accelerator sensor 2 may detect the depression amount (accelerator opening) of the accelerator pedal and output a signal corresponding to the detected accelerator opening. The steering angle sensor 3 may detect the steering angle of the steering wheel (handle) and output a signal voltage corresponding to the detected steering angle.

[0016] Next, a hardware configuration example of the vehicle control device will be described with reference to FIG. 2. FIG. 2 is a hardware configuration diagram of the vehicle control device according to an embodiment of the present disclosure. The vehicle control device 104 may include a processor 10, a memory 20, a communication I / F 30, and an input / output I / F 40. These may be connected to each other via a bus 50 so as to be communicable.

[0017] The processor 10 may be interpreted as a central processing unit. The processor 10 may execute various programs and control each part. The processor 10 may read the vehicle control program 20a from the memory 20 and execute specific processing by expanding the vehicle control program 20a. The functions realized by the vehicle control program 20a will be described later.

[0018] The communication I / F 30 may be interpreted as an interface for the vehicle control device 104 to communicate with other devices. Standards such as CAN (Controller Area Network), Ethernet (registered trademark), Wi-Fi (registered trademark), etc. may be used for the communication I / F 30.

[0019] The input / output I / F 40 may input information detected by a sensor group such as the accelerator sensor 2 shown in FIG. 1.

[0020] Next, referring to FIGS. 3 to 5, the functions of the vehicle control device 104 will be described. FIG. 3 is a functional block diagram of the vehicle control device. FIG. 4 is a diagram for explaining a method of calculating a target speed. FIG. 5 is a diagram showing the μ-s characteristics between the tire and the road surface.

[0021] The vehicle control device 104 may include a target speed calculation unit 104a that calculates a target speed, a turning radius calculation unit 104b that calculates the turning radius of the left and right wheels, front and rear wheels, etc. of the vehicle 100, and a turning correction unit 104c that corrects the turning radius calculated by the turning radius calculation unit 104b. Further, the vehicle control device 104 may include a driving force imbalance correction unit 104d that corrects the driving force imbalance from the difference in driving torque between the left and right wheels or the difference in driving torque between the front and rear wheels, and a rotation speed conversion unit 104e that converts the target speeds of the left and right wheels, front and rear wheels, etc. corrected by the driving force imbalance correction unit 104d into the target rotation speeds of the motors 102 connected to each wheel.

[0022] The target speed calculation unit 104a, the turning radius calculation unit 104b, the turning correction unit 104c, the driving force imbalance correction unit 104d, and the rotation speed conversion unit 104e may be realized by the processor 10 shown in FIG. 2 executing the vehicle control program 20a.

[0023] (Target speed calculation unit 104a, turning radius calculation unit 104b, turning correction unit 104c) The target speed calculation unit 104a may calculate the target speed of the vehicle 100 based on the accelerator opening. The turning radius calculation unit 104b may calculate the turning radius of each drive wheel 1 based on the steering angle of the steering wheel. The turning correction unit 104c may calculate the respective target speeds of each drive wheel 1 based on the target speed of the vehicle 100 calculated by the target speed calculation unit 104a and the turning radius of each drive wheel 1 calculated by the turning radius calculation unit 104b.

[0024] An example of a method for calculating the target speed (Vvhltgt) of the vehicle 100 is shown below. Vvhltgt may be calculated using a preset map or the like from the accelerator opening. (A) From the steering angle θ of the steering wheel, for example, the left wheel tire cut angle σL may be obtained. The relationship between θ and σL may be set in advance as a map or a regression equation. (B) When the wheelbase is WB and the tread is TL, as shown in FIG. 4, the turning radius RL may be calculated by the following equation (1). RL = WB / tan(σL) + TL / 2 ··· (1) (C) Similarly, the turning radius RR may be calculated by the following equation (2). RR = WB / tan(σR) - TL / 2 ··· (2) (D) Generally, since RL and RR do not match, the turning radius R may be calculated by averaging the two using the following equation (3). R = (RR + RL) / 2 ··· (3) (E) The right wheel target speed VRtgt and the left wheel target speed VLtgt may be calculated by the following equations (4) and (5) because they may be set so that the angular velocity from the turning center is equal. VRtgt = (1 + TL / 2R) × Vvhltgt ··· (4) VLtgt = (1 - TL / 2R) × Vvhltgt ··· (5)

[0025] Note that in the above-described conventional technology, VRtgt and VLtgt are used to calculate the MGRR rotation target value NRtgt and the MGRL rotation target value NLtgt by the following equations (6) and (7). Rtir represents the tire dynamic load radius, and GR represents the reduction ratio. NRtgt = VRtgt / Rtir × GR × 60 / 2π ··· (6) NLtgt = VLtgt / Rtir × GR × 60 / 2π ··· (7)

[0026] (Driving force imbalance correction unit 104d) The driving force imbalance correction unit 104d may calculate the difference in the driving force of each of the plurality of motors 102, and calculate a correction amount for correcting the value of the speed command so that the difference or ratio of the driving forces matches a specific target value. Specifically, the driving force imbalance correction unit 104d may calculate, for example, the driving force imbalance correction amount from the difference between the left MG torque and the right MG torque. Hereinafter, the driving force imbalance correction amount may sometimes be simply referred to as the correction amount.

[0027] The correction amount may be obtained directly by PI control from the torque difference between the left and right MGs, but here, in order to facilitate the understanding and the setting of the F / B gain, it is once converted into the relative slip ratio of the left and right. In the conventional control, for example, when the driving force imbalance occurs because the right MG torque is larger than the left MG torque, the slip ratio of each of the pre-correction right wheel and the pre-correction left wheel becomes the position shown in the tire-road surface μ-s characteristic of FIG. 5. The correction amount (correction slip ratio) required to move both of these to the positions of the left and right wheels after correction is 1 / 2 of the left-right relative slip ratio.

[0028] In the slip ratio conversion, the driving force imbalance correction unit 104d may convert it into the slip ratio (ErrSlp) to be corrected per wheel by multiplying the slip ratio conversion coefficient (KTRQ2SLP) by the difference in MG torque as shown in the following equation (8). The slip ratio conversion coefficient (KTRQ2SLP) may be calculated by the following equation (9). Tmgrl represents the left MG torque, Tmgrr represents the right MG torque, Fz represents the tire vertical load. Rtir represents the tire dynamic load radius, GR represents the reduction ratio. Δμs represents the ratio of the friction coefficient to the slip ratio, that is, the slope of the friction coefficient. ErrSlp = (Tmgrl - Tmgrr) × KTRQ2SLP ··· (8) KTRQ2SLP = GR / Rtir / Fz / Δμs / 2 ··· (9)

[0029] In the example of the present disclosure, since the target of the left - right driving force difference is fixed at 0, it is not shown in the functional block diagram. When there is a target of a non - zero left - right driving force difference, the driving force imbalance correction unit 104d may calculate the slip ratio (ErrSlp) according to the following equations (10) and (11). Terrtgt represents the target MG torque difference, and FxDiftgt represents the target driving force difference (a positive value when the right wheel is larger). ErrSlp=(Terrtgt-(Tmgrr - Tmgrl))×KTRQ2SLP···(10) Terrtgt=FxDiftgt×Rtir / GR···(11)

[0030] Next, the driving force imbalance correction unit 104d may calculate the correction amount (CorrFact) according to the following equation (12) for the deviation converted into the slip ratio ErrSlp to be corrected. KP represents the proportional gain, KI represents the integral gain, and 1 / s represents the integral element. CorrFact(s)=KP×ErrSlp(s)+KI×1 / s×ErrSlp(s)···(12)

[0031] The driving force imbalance correction unit 104d corrects the right - wheel target speed (VRtgt) and the left - wheel target speed (VLtgt) according to the following equations (13) and (14) using the above - mentioned correction amount (CorrFact), thereby calculating the right - wheel target speed (CorrVRtgt) after driving force imbalance correction and the left - wheel target speed (CorrVLtgt) after driving force imbalance correction. CorrVRtgt=VRtgt×(1 + CorrFact)···(13) CorrVLtgt=VLtgt×(1 - CorrFact)···(14)

[0032] (Rotation speed conversion unit 104e) The rotational speed conversion unit 104e may convert the target speed of the right wheel and the target speed of the left wheel after the driving force imbalance correction into the corrected right MG target rotational speed (CorrNRtgt) and the corrected left MG target rotational speed (CorrNLtgt) according to the following equations (15) and (16). Rtir represents the dynamic load radius of the tire, and GR represents the reduction ratio. CorrNRtgt = CorrVRtgt / Rtir × GR × 60 / 2π ··· (15) CorrNLtgt = CorrVLtgt / Rtir × GR × 60 / 2π ··· (16)

[0033] As a result, the imbalance of the driving force caused by the difference in the effective tire diameter, the recognition error of the steering angle, etc. can be suppressed, the increase in energy loss can be suppressed, and the increase in tire wear can be prevented.

[0034] (Another configuration example 1 of the driving force imbalance correction unit 104d) The driving force imbalance correction unit 104d may limit the correction amount so that it becomes equal to or less than a specific value. For example, when one of the two left and right driving wheels 1 enters a road surface with a low μ and one wheel slips, if the correction of the aforementioned target speed is carried out without limit, the wheel on the road surface with a high μ will only generate the same driving force as the wheel on the side with a low μ, and the treadability may deteriorate. To suppress this, the correction amount (CorrFact) is preferably limited to a range corresponding to the difference between the target speed of the left and right wheels and the actual speed at the wheel position due to the assumed effective tire diameter difference, the assumed steering angle recognition error, etc. For example, when the left - right difference in the effective tire diameter is assumed to be a maximum of 4% in ratio conversion and the difference between the target speed and the actual speed due to the steering angle recognition error is assumed to be 6% in left - right relative ratio conversion, the total left - right relative error is a maximum of ±10%. Therefore, the correction amount only needs to be about ±5% for one wheel. Therefore, the integral term is preferably limited so that it is not integrated to 0.05 or more, and the proportional term is also preferably limited to about the same or less. As a result, the stack escape performance can be enhanced, and the turning acceleration performance can be improved.

[0035] (Another configuration example 2 of the driving force imbalance correction unit 104d) When an obstacle occurs in estimating the turning radius of the vehicle 100, the driving force imbalance correction unit 104d may relax the correction amount limit or not execute the correction amount limit. For example, when the turning radius cannot be estimated due to a failure of the steering angle sensor 3 or the like, or when the estimation accuracy of the turning radius decreases by estimating the turning radius using an alternative rate gyro or the like, the error between the target speeds of the left and right wheels (VRtgt, VLtgt) and the actual speed at the actual wheel position increases. Therefore, the error range assumed when the sensor is normal is exceeded. In this case, the driving force imbalance cannot be absorbed by the above-described correction amount limit value. Therefore, it is preferable to relax the correction amount limit value so that the error assumed at the time of failure can be absorbed when the turning radius cannot be estimated or the estimation accuracy decreases. Thereby, even when a failure such as that of the steering angle sensor 3 occurs and the turning correction cannot be performed correctly, the driving force imbalance can be effectively suppressed.

[0036] (Another configuration example 3 of the driving force imbalance correction unit 104d) When an obstacle occurs in estimating the turning radius of the vehicle 100 or when the estimation accuracy of the turning radius decreases, the driving force imbalance correction unit 104d may increase the correction gain of the correction amount. The ratio conversion value of the left-right difference in the effective tire diameter is generally a substantially constant value without sudden changes. Also, the difference between the target speeds of the left and right wheels and the actual speed at the wheel position is relatively small when the sensor is normal. Therefore, the correction gain when the sensor is normal is set with emphasis on stability. However, when steering is performed during a failure of the steering angle sensor 3 or the like, the error between the target speeds of the left and right wheels (VRtgt, VLtgt) and the actual speed at the actual wheel position changes rapidly. Therefore, it is preferable for the correction amount CorrFact to follow the change in the error at a high speed. Therefore, when a failure occurs such that the turning radius cannot be estimated or the accuracy decreases, the correction gain is preferably set high within a range that does not lose stability. Thereby, even when a failure such as that of the steering angle sensor 3 occurs and the turning correction cannot be performed correctly, the driving force imbalance can be more effectively suppressed. Also, the driving force imbalance can be suitably suppressed even during a sudden steering operation.

[0037] (Another Configuration Example 4 of Driving Force Unbalance Correction Unit 104d) When the number of revolutions of a plurality of motors 102 or two or more drive wheels 1 is equal to or less than a specific value, the driving force unbalance correction unit 104d may not execute the calculation of the correction amount, and when the number of revolutions exceeds the specific value, the driving force unbalance correction unit 104d may execute the calculation of the correction amount. For example, at low vehicle speeds such as during startup, the vehicle is more likely to be affected by road surface irregularities, so the driving force is likely to change. Also, the number of revolutions and vehicle speed are usually calculated using the normal pulse interval, but at low vehicle speeds, the pulse interval becomes longer and the calculation accuracy decreases, such as the number of revolutions not being updated until the next pulse arrives. If the correction amount is calculated in such a situation, the correction amount may deviate from the intended correction amount. Therefore, in this embodiment, for example, the calculation of the proportional term and the integral term may be performed only when the number of revolutions of both of the two left and right motors 102 is equal to or greater than the specific value. Since the integral term is calculated when the vehicle speed is high and is a value that can absorb the tire diameter difference and the error of the steering angle sensor 3, the calculation is stopped at low vehicle speeds and the previous value is held. Thereby, while suppressing the execution of incorrect correction, when the number of revolutions at which calculation is permitted after starting is reached, an appropriate correction amount can be immediately output.

[0038] (Another Configuration Example 5 of Driving Force Unbalance Correction Unit 104d) When the number of revolutions of the motor 102 is equal to or less than a specific value, the driving force unbalance correction unit 104d may not execute the correction based on the correction amount of the speed command value, and when the number of revolutions of the motor 102 exceeds the specific value, the driving force unbalance correction unit 104d may execute the correction. Specifically, the driving force unbalance correction unit 104d may perform the correction only when the number of revolutions of both of the two left and right motors 102 exceeds the specific value, for example. Thereby, even when one-wheel slip occurs and starting is not possible, since the target speed of the non-slip wheel is corrected and a decrease in driving torque is suppressed, the stack escape performance is improved.

[0039] Next, the operation of the vehicle control device 104 of the present disclosure will be described with reference to FIGS. 6 and 7A to 7D. FIG. 6 is a flowchart for explaining the operation of the vehicle control device according to the embodiment of the present disclosure. FIGS. 7A to 7D are diagrams for explaining the operation of the vehicle control device according to the embodiment of the present disclosure.

[0040] The vehicle control device 104 calculates the target speed of each drive wheel 1 in step S1, calculates the difference in driving force in step S2, and calculates the correction amount in step S3.

[0041] In FIGS. 7A, 7B, 7C, and 7D, the target speed (left and right MG target rotation speeds), the actual speed at the wheel position (left and right MG rotation speeds), the left and right MG torques, the correction amount (PIterm, Iterm), etc. are shown.

[0042] For example, when the tire air pressure of the left wheel decreases and the effective tire diameter is smaller than that of the right wheel, as shown in FIG. 7A, by correction, the left MG target rotation speed (dashed-dotted line) becomes higher than the right MG target rotation speed (solid line). In this case, as shown in FIG. 7B, the left MG rotation speed (dashed-dotted line) becomes higher than the right MG rotation speed (solid line). As shown in FIG. 7C, by correcting the value of the speed command so that the difference or ratio between the left wheel driving torque (left MG torque) and the right wheel driving torque (right MG torque) matches a specific target value, equivalent driving torques are generated in the left and right motors 102.

[0043] As shown in FIG. 7D, until both the left and right motors 102 after starting reach a predetermined rotation speed, the value during forward travel is maintained in the I term (Iterm: dashed-dotted line). The actual correction amount (PIterm: solid line) is fixed at 0 until both the left and right motors 102 after starting reach a predetermined rotation speed. When both the left and right motors 102 reach a predetermined rotation speed, the integration of the I term and the calculation of the P term are started, and the actual correction amount (PIterm) is output.

[0044] Note that although the PI term changes smoothly, this is because it is output through a low-pass filter not shown in FIG. 3. The low-pass filter is set to cut the torsional resonance frequency so that the correction amount does not fluctuate due to torsional resonance of the drive system or the like. For a while after the vehicle 100 starts, since the right MG torque > the left MG torque, the correction amount grows in the negative direction, making the corrected left MG target rotation speed (CorrNLtgt) higher than the corrected right MG target rotation speed (CorrNRtgt). As a result, the left MG torque increases and the right MG torque decreases, and it can be seen that they are almost balanced and match in the latter half of the figure.

[0045] FIGS. 8A to 8C are diagrams for explaining a control example of driving torque according to a comparative example. FIGS. 8A to 8C show the target speed (left and right MG target rotation speeds), the actual speed at the wheel position (left and right MG rotation speeds), the left and right MG torques, and the like. For example, when the tire air pressure of the left wheel decreases, the effective tire diameter of the left wheel becomes smaller than that of the right wheel. Therefore, even when the vehicle 100 is in a straight-ahead state, only the left wheel requires a high rotation speed. However, actually, during straight-ahead driving, since the target rotation speeds are the same (see FIG. 8A), the left wheel becomes regenerative (see FIG. 8C), and the driving force of the right wheel increases to maintain the vehicle speed, resulting in an imbalance in the driving force.

[0046] Also, when there is an error in recognizing the steering angle, the correction amount of the target speed according to the turning radius calculated is different from the correction amount of the target speed required at the actual turning radius. Therefore, in the control example of driving torque according to the comparative example, an imbalance in the driving force also occurs.

[0047] Furthermore, when the steering angle sensor 3 fails, the correction of the target speed according to the turning radius cannot be performed. Therefore, in the control example of driving torque according to the comparative example, a large imbalance in the driving force occurs during turning.

[0048] When these imbalances in the driving force occur, as described in Patent Document 1 mentioned above, problems such as an increase in energy loss and early wear of the tires may occur.

[0049] Note that the vehicle 100 to which the vehicle control device 104 of the present disclosure can be applied is not limited to a vehicle 100 in which motors 102 are directly connected to the left and right wheels behind the vehicle 100. For example, as shown in FIG. 9A, the vehicle 100 in which motors 102 are directly connected to each of the four wheels may also be applicable. Further, as shown in FIG. 9B, the vehicle 100 to which the vehicle control device 104 can be applied may be a vehicle 100 in which the motor 102 for the front wheels is connected to the left and right wheels (front wheels) in front of the vehicle 100 and the motor 102 for the rear wheels is connected to the left and right wheels (rear wheels) behind the vehicle 100 via a differential.

[0050] In the vehicle 100 shown in FIG. 9A, the sum of the driving forces of the left and right wheels in front of the vehicle 100 and the sum of the driving forces of the left and right wheels behind the vehicle 100 may be corrected so that the front-to-rear driving force ratio matches the ratio of the shared loads of the front and rear axles. Thereafter, the left and right wheels in front of the vehicle 100 may be corrected by the method described above, and the left and right wheels behind the vehicle 100 may be corrected in the same manner.

[0051] In the vehicle 100 shown in FIG. 9B, by correcting the driving force so that the front-to-rear driving force ratio matches the ratio of the shared loads of the front and rear axles, slip can be effectively suppressed and the frictional force between the road surface and the tires can be utilized. In this case, it is still better to calculate the ratio of the shared loads in consideration of the load transfer during acceleration and deceleration.

[0052] (Addendum) Regarding the above-described embodiments, the following addendum is further disclosed.

[0053] (Addendum 1) A vehicle control device that includes at least one processor and controls a plurality of motors respectively connected to two or more drive wheels provided on a vehicle according to a speed command, wherein the processor calculates the difference in driving force of each of the plurality of motors, and calculates a correction amount for correcting the value of the speed command so that the difference or ratio of the driving forces matches a specific target value.

[0054] (Addendum 2) The vehicle control device according to Supplementary Note 1, wherein the processor restricts the correction amount so as to be equal to or less than a specific value.

[0055] (Supplementary Note 3) The vehicle control device according to Supplementary Note 2, wherein the processor relaxes or does not execute the restriction when an obstacle occurs in estimating the turning radius of the vehicle.

[0056] (Supplementary Note 4) The vehicle control device according to any one of Supplementary Notes 1 to 3, wherein the processor increases the correction gain of the correction amount when an obstacle occurs in estimating the turning radius of the vehicle.

[0057] (Supplementary Note 5) The vehicle control device according to any one of Supplementary Notes 1 to 4, wherein the processor does not execute the calculation of the correction amount when the rotational speeds of the plurality of motors or the two or more drive wheels are equal to or less than a specific value, and executes the calculation of the correction amount when the rotational speeds exceed the specific value.

[0058] (Supplementary Note 6) The vehicle control device according to Supplementary Note 5, wherein the processor does not execute the correction of the value of the speed command by the correction amount when the rotational speed is equal to or less than the specific value, and executes the correction when the rotational speed exceeds the specific value.

[0059] (Supplementary Note 7) Controlling a plurality of motors respectively connected to two or more drive wheels provided on a vehicle according to a speed command, Calculating a difference in driving force of each of the plurality of motors, A vehicle control program that causes a computer to calculate a correction amount for correcting the value of the speed command so that the difference or ratio of the driving forces matches a specific target value.

[0060] (Supplementary Note 8) Controlling a plurality of motors respectively connected to two or more drive wheels provided on a vehicle according to a speed command, Calculating a difference in driving force of each of the plurality of motors, A vehicle control method executed by a processor, which calculates a correction amount for correcting the value of the speed command so that the difference or ratio of the driving forces matches a specific target value.

[0061] The control unit and its method described in the present disclosure may be realized by a dedicated computer configured with a processor programmed to execute one or more functions embodied by a computer program. Alternatively, the device and its method described in the present disclosure may be realized by a dedicated computer configured with a processor by dedicated hardware logic circuits. Or, the device and its method described in the present disclosure may be realized by one or more dedicated computers configured by a combination of a processor that executes a computer program and one or more hardware logic circuits. Also, the computer program may be stored in a computer-readable non-transitory tangible recording medium as instructions to be executed by a computer.

Explanation of Signs

[0062] 1 Driving wheel 2 Accelerator sensor 3 Steering angle sensor 4 Rotation sensor 10 Processor 20 Memory 20a Vehicle control program 30 Communication I / F 40 Input / output I / F 50 Bus 100 Vehicle 101 Battery 102 Motor 103 Inverter 104 Vehicle control device 104a Target speed calculation unit 104b Turning radius calculation unit 104c Turning correction unit 104d Driving force imbalance correction unit 104e Rotation speed conversion unit

Claims

1. A vehicle control device that includes at least one processor and controls a plurality of motors respectively connected to two or more drive wheels provided on a vehicle according to a speed command, wherein the processor calculates a difference in driving force of each of the plurality of motors, and calculates a correction amount for correcting the value of the speed command so that the difference or ratio of the driving forces matches a specific target value.

2. The vehicle control device according to claim 1, wherein the processor applies a limit to the correction amount so that it is equal to or less than a specific value.

3. The vehicle control device according to claim 2, wherein the processor relaxes or does not execute the limit when an obstacle occurs in estimating the turning radius of the vehicle.

4. The vehicle control device according to any one of claims 1 to 3, wherein the processor increases a correction gain of the correction amount when an obstacle occurs in estimating the turning radius of the vehicle.

5. The vehicle control device according to claim 1, wherein the processor does not execute the calculation of the correction amount when the rotational speed of the plurality of motors or the two or more drive wheels is equal to or less than a specific value, and executes the calculation of the correction amount when the rotational speed exceeds the specific value.

6. The vehicle control device according to claim 5, wherein the processor does not execute the correction of the value of the speed command by the correction amount when the rotational speed is equal to or less than the specific value, and executes the correction when the rotational speed exceeds the specific value.

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