Vehicle control device and vehicle control method

Abstract

To easily adjust the torque of each wheel according to the load condition. [Solution] The vehicle control device 10 according to the embodiment has a controller 12 that controls in-wheel motors 22 that drive each of the wheels provided on the vehicle 1. The controller 12 controls the in-wheel motors 22 according to a target rotational speed and detects the front and rear load state of the vehicle based on the torque state of the in-wheel motors 22 while the vehicle 1 is moving laterally when the in-wheel motors 22 are controlled according to the target rotational speed.

Description

Technical Field

[0001] The present invention relates to a vehicle control device and a vehicle control method.

Background Art

[0002] In a vehicle equipped with four in-wheel motors (IWM), torque distribution of each wheel is adjusted according to the driving state. In large vehicles such as trucks and buses, the load distribution between the front and rear wheels changes due to the load.

[0003] Therefore, considering traction, it is advantageous to distribute more torque to the side where the load is applied. Also, by grasping the load state of the vehicle, such torque distribution becomes possible.

[0004] Conventionally, a technique of providing a weight sensor in a vehicle to detect the load state of the vehicle is known (see, for example, Patent Document 1).

Prior Art Documents

Patent Documents

[0005]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0006] However, the conventional technology has a problem that it is difficult to adjust the torque of each wheel according to the load state. The load state is, for example, the front - rear distribution of the load and changes due to loading of goods or the like.

[0007] For example, the technique described in Patent Document 1 requires attaching a dedicated weight sensor to the vehicle, increasing the cost.

[0008] Furthermore, it is conceivable to estimate the load state using output torque, acceleration, and tilt sensor values ​​during driving. However, accurate load estimation is difficult because various factors such as road surface gradient and air pressure affect acceleration.

[0009] The present invention has been made in view of the above, and aims to facilitate torque adjustment of each wheel according to the load condition. [Means for solving the problem]

[0010] The vehicle control device according to the present invention has a controller that controls the motors that drive each of the wheels of a vehicle capable of lateral movement. The controller controls the motors according to a target rotational speed and detects the front and rear load conditions of the vehicle based on the torque state of the motors while the vehicle is moving laterally when the motors are controlled according to the target rotational speed. [Effects of the Invention]

[0011] The torque output by the motor driving the wheels changes depending on the load on the wheels, even if the specified target rotational speed remains the same. This invention utilizes this fact to detect the load state for each vehicle position corresponding to each wheel, without using a load sensor, in accordance with the torque output by the motor, and the detected load state can be used for torque adjustment. Therefore, the torque of each wheel can be easily adjusted according to the load state. [Brief explanation of the drawing]

[0012] [Figure 1] Figure 1 shows an example of the configuration of a vehicle according to this embodiment. [Figure 2] Figure 2 is a functional block diagram of the vehicle control system. [Figure 3] Figure 3 illustrates the control of an in-wheel motor according to the load condition. [Figure 4] Figure 4 illustrates the control of an in-wheel motor according to the load condition. [Figure 5]Figure 5 is a flowchart showing the processing flow of the controller. [Modes for carrying out the invention]

[0013] Hereinafter, embodiments of the vehicle control device and vehicle control method disclosed in this application will be described in detail with reference to the attached drawings. However, the present invention is not limited to the embodiments described below.

[0014] The configuration of the vehicle according to the embodiment will be explained using Figure 1. Figure 1 is a diagram showing an example of the configuration of the vehicle according to the embodiment. The entire vehicle or a part of it may be called the vehicle control system.

[0015] As shown in Figure 1, the vehicle 1, which is capable of lateral movement in addition to normal forward and backward movement, has a vehicle control device 10. The vehicle control device 10 is, for example, a VCU (Vehicle Control Unit). The vehicle 1 also has a wheel 21LF, an in-wheel motor 22LF, a wheel 21RF, an in-wheel motor 22RF, a wheel 21LR, an in-wheel motor 22LR, a wheel 21RR, and an in-wheel motor 22RR.

[0016] The alphabetical sequences "LF," "RF," "LR," and "RR" included in the symbols correspond to the left front wheel, right front wheel, left rear wheel, and right rear wheel, respectively. For example, in-wheel motor 22RF drives the right front wheel 21RF. When the corresponding wheels are not distinguished, the alphabetical sequences may be omitted from each symbol. For example, in-wheel motors 22LF, 22RF, 22LR, and 22RR may all be referred to simply as in-wheel motor 22. The in-wheel motor 22 includes a control computer capable of communicating with the vehicle control device 10.

[0017] The positive direction of the x-axis in FIG. 1 (the left direction of the drawing where the arrow points) is defined as the front of the vehicle 1, and the negative direction of the x-axis (the right direction of the drawing) is defined as the rear. Also, the positive direction of the y-axis (the upward direction of the drawing where the arrow points) is defined as the right, and the negative direction of the y-axis (the downward direction of the drawing) is defined as the left. The right or left direction may be referred to as the lateral direction. Further, the positive direction of the z-axis (the front side of the drawing where the arrow points) is vertically upward, and the negative direction of the z-axis (the back side of the drawing) is vertically downward. Also, the turning and rotating directions are described based on looking down on the vehicle 1 from above, that is, with the vertically downward direction as the reference. For example, a right turn is when the vehicle 1 turns so as to turn right.

[0018] The in-wheel motor 22 controls the wheel 21 in response to a signal received from the vehicle control device 10. For example, the vehicle control device 10 can transmit signals to the in-wheel motor 22LF, the in-wheel motor 22RF, the in-wheel motor 22LR, and the in-wheel motor 22RR by CAN (Controller Area Network) communication.

[0019] In addition to the communication function, the in-wheel motor 22 includes a motor and a drive circuit of the motor, etc. The in-wheel motor 22 controls the rotation state of the wheel 21 connected to the motor by driving and controlling the motor by the drive circuit of the motor based on a control value (for example, a torque command value or a target rotational speed) obtained from the received signal.

[0020] As shown in FIG. 1, the vehicle control device 10 has an interface 11, a controller 12, and a memory 13.

[0021] The interface 11 performs input and output of data between the vehicle control device 10 and other devices (for example, the in-wheel motor 22). For example, the interface 11 is a port corresponding to USB (Universal Serial Bus), Ethernet (registered trademark), CAN, etc.

[0022] The controller 12 reads and executes the program stored in memory 13. The controller 12 can be a CPU (Central Processing Unit), DSP (Digital Signal Processor), FPGA (Field Programmable Gate Array), GPU (Graphics Processing Unit), SoC (System on a Chip), etc.

[0023] The controller 12 may be a single processor. The controller 12 may be a multi-processor configuration. Alternatively, the controller 12 may be a multi-core configuration having multiple cores within a single chip connected by a single socket.

[0024] The controller 12 implements the processing units shown in Figure 2 by executing a program. Figure 2 is a functional block diagram of the vehicle control device. As shown in Figure 2, the controller 12 has a drive control unit 121, a determination unit 122, and a calculation unit 123. These processing units allow the controller 12 to control the in-wheel motors 22 that drive each of the multiple wheels provided on the vehicle 1.

[0025] The drive control unit 121 transmits control values ​​to the in-wheel motor 22. In this embodiment, the drive control unit 121 transmits a target rotational speed or a target torque as the control value.

[0026] During normal driving, the drive control unit 121 performs torque control. Specifically, the drive control unit 121 transmits the target torque for each wheel (in-wheel motor). The target torque for each wheel (in-wheel motor) is corrected by the vehicle control device 10 or other control devices based on the accelerator opening and ratio information 131 stored in memory 13. The ratio information 131 is information indicating the ratio of the front and rear loads of the vehicle 1.

[0027] On the other hand, during lateral movement, the drive control unit 121 performs target rotational speed control. That is, the drive control unit 121 transmits the target rotational speed for each wheel (in-wheel motor). During lateral movement, the drive control unit 121 basically moves the vehicle sideways, so it drives all in-wheel motors to the same target rotational speed. Also, since the target rotational speed control is configured to control each wheel (in-wheel motor) to the target rotational speed, differences in the rotational speed of the front and rear wheels (in-wheel motors) are unlikely to occur due to the front and rear loads. Therefore, in the target rotational speed control during lateral movement, no correction of the control value based on the ratio information 131 is performed.

[0028] The determination unit 122 determines the state of the vehicle and whether specific conditions (such as whether it is moving laterally) are met. The calculation unit 123 calculates the ratio of the front and rear loads of the vehicle 1. The calculation unit 123 also stores the calculated ratio in the ratio information 131.

[0029] Here, vehicle 1 can move directly sideways because it employs in-wheel motors 22 and has independent steering for all four wheels. In this case, the wheels 21 are oriented in the lateral direction, that is, parallel to the y-axis.

[0030] In vehicles, especially those with long wheelbases such as trucks and buses, a turning motion can occur during lateral movement due to differences in the load on the front and rear wheels. For example, if you want to move sideways, but the torque is output with the same distribution between the front and rear wheels according to the throttle opening, the vehicle will turn around on the side with the heavier load and higher load (for example, the rear wheels in the case of a truck loaded with cargo at the rear).

[0031] To suppress this turning, the controller 12 of this embodiment uses rotational speed control for the in-wheel motors during lateral movement. Also, since the control is basically performed to move laterally in a straight line during lateral movement, the rotational speeds of the front and rear wheels are controlled to be the same. Rotational speed control is a control method that instructs the in-wheel motors to reach a target rotational speed according to the accelerator opening. In this case, the front and rear wheels are controlled to reach a rotational speed that matches the target rotational speed regardless of the load, so the occurrence of turning can be suppressed. Specifically, in rotational speed control, the in-wheel motor 22 targets a speed (rotational speed) according to the accelerator opening, and through F / B (feedback) control, if the speed is low, the motor output is increased to bring the actual rotational speed closer to the target rotational speed.

[0032] Furthermore, the controller 12 can estimate the front and rear load conditions of the vehicle 1 by utilizing the fact that the torque output of each wheel increases or decreases according to the load as a result of rotational control during the lateral movement of the vehicle 1.

[0033] Specifically, the controller 12 calculates the torque of each wheel from the motor output (output power = motor current × motor voltage) and motor rotation speed. The motor current, voltage, rotation speed, etc., are detected by sensors attached to the motor. Then, the controller 12 calculates the front and rear load state (front and rear load distribution) from the ratio of the calculated torques of the front and rear wheels.

[0034] The control of the in-wheel motor 22 by the controller 12 will be explained using Figures 3 and 4. Figures 3 and 4 illustrate the control of the in-wheel motor according to the load condition.

[0035] The controller 12 controls the in-wheel motor 22 according to the target rotational speed and detects the front and rear load state of the vehicle 1 based on the torque output by the in-wheel motor 22 during lateral movement. During lateral movement, the vehicle 1 moves laterally as the in-wheel motor 22 is controlled according to the target rotational speed.

[0036] Figure 3 illustrates the control of the in-wheel motor according to the load condition. As shown in Figure 3, the cargo compartment of vehicle 1 is empty. In this case, the load on the front wheels of vehicle 1 is considered to be greater than that on the rear wheels. The front wheels consist of wheels equipped with wheel 21LF and wheels equipped with wheel 21RF. The rear wheels consist of wheels equipped with wheel 21LR and wheels equipped with wheel 21RR. Note that the wheels include a wheel and a tire as components.

[0037] The controller 12 controls each of the in-wheel motors 22 according to the same target rotational speed during lateral movement. Therefore, when the load on the front wheels is large, the torque output by in-wheel motors 22LF and 22RF becomes larger than the torque output by in-wheel motors 22LR and 22RR. The controller 12 detects the load state based on the magnitude of the torque output by the in-wheel motors 22.

[0038] Thus, the controller 12 uses the same target rotational speed as the rotational speed command. In control using this target rotational speed, a change in motor output occurs in response to the load, and the change in torque of each wheel can be detected in accordance with this change. Then, the load distribution between the front and rear of the vehicle can be detected from the detected torques of the front and rear wheels without the need for load sensors.

[0039] Specifically, the controller 12 controls the in-wheel motors 22, each of which is located on the left front wheel, right front wheel, left rear wheel, and right rear wheel, according to the target rotational speed during lateral movement. The left front wheel is located on the front left side of the vehicle 1. The right front wheel is located on the front right side of the vehicle 1. The left rear wheel is located on the rear left side of the vehicle 1. The right rear wheel is located on the rear right side of the vehicle 1. The controller 12 then detects the front and rear load conditions of the vehicle 1 based on the relationship between the front wheel torque and the rear wheel torque when the vehicle 1 is moving to the right or left, while the in-wheel motors 22 are controlled according to the target rotational speed.

[0040] The front wheel torque is the torque output by at least one of the in-wheel motors 22 corresponding to the left front wheel and the in-wheel motor 22 corresponding to the right front wheel. The rear wheel torque is the torque output by at least one of the in-wheel motors 22 corresponding to the left rear wheel and the in-wheel motor 22 corresponding to the right rear wheel. The front wheel torque and rear wheel torque may be any one of a plurality of output torques, the sum of a plurality of output torques, or the average of a plurality of output torques.

[0041] For example, the controller 12 calculates the ratio of front wheel torque to rear wheel torque as the front-to-rear load ratio of vehicle 1. For example, if the ratio of front wheel torque to rear wheel torque is "front wheel torque / rear wheel torque = 2", the controller 12 calculates "front load / rear load = 2".

[0042] Thus, the controller 12 detects a smaller rear load relative to the front load of the vehicle 1 the greater the front wheel torque is compared to the rear wheel torque. This makes it easier to adjust the torque when the vehicle 1 is not loaded with cargo.

[0043] Furthermore, the controller 12 corrects the control amount of the in-wheel motors 22 when the vehicle 1 is moving forward or backward (during normal driving) based on the detected front and rear load conditions of the vehicle 1. For example, the controller 12 corrects the target torque of each in-wheel motor 22 so that the ratio of the target torque of the front wheels to the target torque of the rear wheels increases as the front-to-rear load ratio increases.

[0044] Figure 4 illustrates the control of the in-wheel motor according to the load condition. As shown in Figure 4, the cargo compartment of vehicle 1 is full. In this case, the rear wheel torque is greater than the front wheel torque. For example, if the ratio of the front wheel torque to the rear wheel torque is "front wheel torque / rear wheel torque = 1 / 2", the controller 12 calculates "front load / rear load = 1 / 2".

[0045] Thus, the controller 12 detects a larger rear load relative to the front load of the vehicle 1 the smaller the front wheel torque is compared to the rear wheel torque. This makes it easier to adjust the torque when the vehicle 1 is loaded with cargo.

[0046] Figure 5 will be used to explain the processing flow of controller 12. Figure 5 is a flowchart showing the processing flow of the controller.

[0047] As shown in Figure 5, the controller 12 determines whether or not the vehicle 1 is moving laterally (step S101). For example, the controller 12 makes this determination based on whether or not the wheels are oriented laterally, and whether or not the internal mode of the vehicle 1 is in lateral movement mode.

[0048] If vehicle 1 is not moving laterally (step S101; No), the controller 12 determines whether the clear condition is met (step S102). The clear condition is met when it is considered that the load state of vehicle 1 has changed. For example, the clear condition is that the cargo bed of vehicle 1 has been released for a certain period of time or longer.

[0049] If the clearing condition is met (step S102; Yes), the controller 12 clears the front-to-rear ratio stored in memory 13 (step S103). In other words, when the load state of vehicle 1 changes, the controller 12 initializes the estimated value of the load state.

[0050] If the clear conditions are not met (Step S102; No), controller 12 proceeds to Step S106.

[0051] If vehicle 1 is moving laterally (step S101; Yes), the controller 12 determines whether the speed of vehicle 1 is stable (step S104). For example, the controller 12 determines that the speed is stable if the difference between the maximum and minimum speeds over a certain period in the past is within a threshold.

[0052] If the speed is stable (step S104; Yes), the controller 12 calculates the front-to-rear load ratio based on the torque output by each in-wheel motor 20 and stores it in the memory 13 (step S105). For example, the controller 12 calculates the front-to-rear load ratio based on the ratio of front wheel torque to rear wheel torque.

[0053] If the speed is not stable (step S104; No), the controller 12 proceeds to step S106.

[0054] The controller 12 then controls the in-wheel motor 20 based on the front-to-rear ratio (step S106). Note that during lateral movement, the controller 12 does not need to use the front-to-rear ratio to control the in-wheel motor 20, or it may use it to adjust the torque by F / F (feedforward). On the other hand, during normal driving, the controller 12 corrects the target torque of the in-wheel motor 20 based on the front-to-rear ratio.

[0055] According to this embodiment, the controller 12 can detect the load distribution on the front and rear wheels without additional load sensors by using the torque output of the in-wheel motor 20. Furthermore, the controller 12 can detect not only the increase or decrease in load but also the front-to-rear distribution by performing estimations during lateral movement. As a result, it becomes easier to adjust the torque of each wheel according to the load condition.

[0056] Furthermore, even when there is a lateral slope, the torque ratio remains unchanged, allowing the controller 12 to detect the load distribution.

[0057] During normal driving, the controller 12 controls the front-to-rear torque distribution based on the detected load distribution, thereby obtaining appropriate traction.

[0058] Furthermore, the controller 12 can adjust the torque using feedforward (F / F) based on the detected load distribution during lateral movement. This allows the controller 12 to improve its ability to maintain straight-line movement by using the detected load distribution during lateral movement.

[0059] Further effects and modifications can be readily derived by those skilled in the art. Therefore, broader aspects of the present invention are not limited to the specific details and representative embodiments expressed and described above. Accordingly, various modifications are possible without departing from the spirit or scope of the overall concept of the invention as defined by the appended claims and equivalents. [Explanation of Symbols]

[0060] 1 vehicle 10. Vehicle control system 11 Interfaces 12 controllers 13 memory 21, 21LF, 21RF, 21LR, 21RR wheels 22, 22LF, 22RF, 22LR, 22RR In-wheel motors 121 Drive control unit 122 Judgment section 123 Calculation Department 131 Ratio information

Claims

1. It has a controller that controls the motors that drive each of the multiple wheels equipped on a vehicle capable of lateral movement, The aforementioned controller, The motor is controlled according to the target rotational speed, The front and rear load states of the vehicle are detected based on the torque output of the motor while the vehicle is moving laterally, when the motor is controlled according to the target rotational speed. Vehicle control system.

2. The aforementioned controller, Based on the detected front and rear load conditions of the vehicle, the control amount of the motor is corrected while the vehicle is moving forward or backward. The vehicle control device according to claim 1.

3. The aforementioned controller, While the vehicle is moving laterally, each of the motors is controlled according to the same target rotational speed. The vehicle control device according to claim 1.

4. The aforementioned controller, The motors provided on the left front wheel located on the front left side of the vehicle, the right front wheel located on the front right side of the vehicle, the left rear wheel located on the rear left side of the vehicle, and the right rear wheel located on the rear right side of the vehicle are controlled according to the target rotational speed. The front and rear load conditions of the vehicle are detected based on the relationship between the torque output by at least one of the motors corresponding to the left front wheel and the right front wheel when the vehicle is moving to the right or left, and the torque output by at least one of the motors corresponding to the left rear wheel and the right rear wheel, when the motors are controlled according to the target rotational speed. The vehicle control device according to claim 1.

5. The controller detects a greater rearward load relative to the front load of the vehicle the smaller the torque output by at least one of the motors corresponding to the left front wheel and the right front wheel is compared to the torque output by at least one of the motors corresponding to the left rear wheel and the right rear wheel. The vehicle control device according to claim 4.

6. A controller that controls the motors that drive each of the multiple wheels on a vehicle capable of lateral movement, The motor is controlled according to the target rotational speed, The front and rear load states of the vehicle are detected based on the torque output of the motor while the vehicle is moving laterally, when the motor is controlled according to the target rotational speed. Vehicle control method.

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