Vehicle control device and vehicle control method

Abstract

To provide a vehicle control device and a vehicle control method that can reduce the feeling of discomfort caused by the change in speed when switching to reverse. [Solution] The vehicle control device according to the embodiment is a vehicle control device that drives and controls a motor for driving attached to a vehicle, and includes a controller that controls the rotational speed so that the motor reaches a target rotational speed. The controller decreases the target rotational speed by a first change amount during deceleration in forward control, and increases the target rotational speed by a second change amount smaller than the first change amount during acceleration in reverse control. When the controller receives a switching input to reverse control during forward control and transitions to reverse control, if the target rotational speed is greater than a threshold, it continues rotational speed control that decreases the target rotational speed by the first change amount.

Description

Technical Field

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

Background Art

[0002] Conventionally, in a vehicle such as an electric wheelchair, when an operation to switch the traveling direction is performed, a switchback state may occur in which the traveling direction of the driving control and the actual traveling direction are temporarily opposite until the vehicle stops and the traveling direction is switched. For example, Patent Document 1 discloses a technique for reducing a torque shock generated when the switchback state is eliminated by adjusting the distribution of brake torque and regenerative torque when the switchback state occurs.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] However, in the prior art, there is room for improvement in reducing the discomfort with respect to the speed change during the switchback state. Generally, the acceleration and deceleration during the reverse travel of the vehicle are gentler than those during the forward travel. Therefore, when a passenger makes a switching input to reverse while the vehicle is moving forward, the vehicle decelerates at the deceleration during reverse travel instead of the deceleration during forward travel during the period from the forward state to a stop. That is to say, when a switching input is made while the vehicle is moving forward, although the vehicle is decelerating while moving forward, it decelerates gently at the deceleration during reverse travel, so there is a possibility that the passenger may feel discomfort with respect to the speed change.

[0005] The present invention has been made in view of the above, and aims to provide a vehicle control device and a vehicle control method that can reduce the sense of discomfort caused by changes in speed when switching to reverse. [Means for solving the problem]

[0006] To solve the above-mentioned problems and achieve the objective, the vehicle control device according to the present invention is a vehicle control device that drives and controls a motor for driving attached to a vehicle, and includes a controller that controls the rotational speed of the motor so that it reaches a target rotational speed. The controller decreases the target rotational speed by a first change amount during deceleration in forward control, increases the target rotational speed by a second change amount smaller than the first change amount during acceleration in reverse control, and when the controller receives a switching input to reverse control during forward control and transitions to reverse control, if the target rotational speed is greater than a threshold, it continues rotational speed control that decreases the target rotational speed by the first change amount. [Effects of the Invention]

[0007] According to the present invention, if the motor's target rotational speed is greater than a threshold when switching to reverse control, the rotational speed control that reduces the target rotational speed by the first change amount is continued. As a result, when switching to reverse control, if the motor's target rotational speed is greater than a threshold, deceleration can be continued at the deceleration rate used during forward movement. Therefore, since there is no switch from the first change amount to the second change amount during deceleration while moving forward, the sense of unnaturalness regarding the speed change when switching to reverse can be reduced. [Brief explanation of the drawing]

[0008] [Figure 1A] Figure 1A shows an example of the vehicle configuration according to this embodiment. [Figure 1B] Figure 1B shows an example of control information stored by a vehicle control device. [Figure 2] Figure 2 is a block diagram showing an example configuration of a vehicle control device according to an embodiment. [Figure 3]Figure 3 is a diagram illustrating rotational speed control during the transition from forward to reverse. [Figure 4] Figure 4 is a flowchart showing the processing procedure for switching to reverse using a vehicle control device according to an embodiment. [Figure 5] Figure 5 illustrates the switching process for the amount of change related to the modified example. [Figure 6] Figure 6 illustrates the switching process for the amount of change related to the modified example. [Figure 7] Figure 7 illustrates the switching process for the amount of change related to the modified example. [Modes for carrying out the invention]

[0009] The vehicle control device and vehicle control method according to the embodiments will be described in detail below with reference to the attached drawings. However, the present invention is not limited to the embodiments shown below.

[0010] First, an example of the vehicle configuration according to the embodiment will be described using Figure 1A. Figure 1A is a diagram showing an example of the vehicle configuration according to the embodiment. The vehicle V shown in Figure 1A is a single-seat electric vehicle for people with mobility impairments, such as the elderly, and moves by driving motors built into the wheels according to the operator's commands.

[0011] Vehicle V is a personal mobility device, such as an electric wheelchair or electric cart. While Vehicle V is, for example, a single-seater, it may also be a vehicle capable of carrying two or more people. Furthermore, Vehicle V is not limited to the wheelchair type shown in Figure 1A; it may be various types, such as a cart or a standing-type vehicle.

[0012] As shown in Figure 1A, the vehicle V comprises a vehicle control device 1, an operating lever 10, a reverse switch 11, front wheels 12, rear wheels 13, and a motor 14.

[0013] The operation lever 10 is arranged, for example, on the side of the seat where the occupant sits and receives operations for driving the vehicle V. Specifically, the operation lever 10 is arranged on either of the left or right armrests. The occupant can operate the operation lever 10 to drive the vehicle V forward and perform maneuvers such as turning right or left.

[0014] More specifically, the operation lever 10 is configured as a joystick and advances the vehicle V at a traveling speed set for each tilting angle of the joystick. Note that the operation lever 10 may have a lever for forward movement and a lever for turning right or left arranged separately. Also, the operation part for forward movement is not limited to the operation lever 10 and may be a pedal-type operation part such as an accelerator pedal.

[0015] The reverse switch 11 is a switch for switching the traveling direction of the vehicle V from forward to reverse. When the reverse switch 11 is pressed by the occupant, it notifies the vehicle control device 1 of an instruction to switch to reverse. When the reverse switch 11 is pressed, the vehicle control device 1 reverses the vehicle V at a preset vehicle speed (target rotational speed). Note that the reverse switch 11 may be a lever member that moves forward to go forward and moves backward to go backward.

[0016] The front wheels 12 are a pair of left and right wheels. In the present disclosure, the front wheels 12 are driven wheels not connected to the motor 14. The rear wheels 13 are a pair of left and right wheels. The rear wheels 13 are drive wheels connected to the motor 14. That is, the motor 14 is a traveling motor that drives the vehicle V to travel by rotational driving. Hereinafter, the left rear wheel 13 and the motor 14 on the left side are referred to as the left rear wheel 13L and the left motor 14L, and the right rear wheel 13 and the motor 14 on the right side are referred to as the right rear wheel 13R and the right motor 14R.

[0017] Note that the motor 14 is not limited to being connected to the rear wheels 13 and may be connected to the front wheels 12. Alternatively, the motor 14 may be independently connected to both the front wheels 12 and the rear wheels 13.

[0018] The vehicle control device 1 is a control device that controls the running of the vehicle V. Specifically, when the vehicle is moving forward, the vehicle control device 1 controls the rotational speed of the motor 14 so that it becomes the target rotational speed set based on the tilt angle of the operation lever 10. Specifically, the vehicle control device 1 performs rotational speed control by transmitting a control signal, which is a command value of the target rotational speed, to the left inverter 20L and the right inverter 20R (see FIG. 2). Specifically, the left inverter 20L and the right inverter 20R perform rotational speed control by feedback control so that the actual rotational speed of the motor 14 becomes the target rotational speed.

[0019] Here, the rotational speed control will be described in detail using FIG. 1B. FIG. 1B is a diagram showing an example of the control information 31 (see FIG. 2) stored in the vehicle control device 1. As shown in FIG. 1B, the vehicle control device 1 refers to the control information 31 and changes the target rotational speed by the change amount set in the control information 31.

[0020] Specifically, the control information 31 includes information on the change amounts of the target rotational speed during acceleration and deceleration for both forward and backward movements. Specifically, as shown in FIG. 1B, when the vehicle is moving forward, the vehicle control device 1 increases the target rotational speed by the forward acceleration during acceleration. Also, when the vehicle is moving forward, the vehicle control device 1 decreases the target rotational speed by the forward deceleration during deceleration. When the vehicle is moving backward, the vehicle control device 1 increases the target rotational speed by the backward acceleration during acceleration. Also, when the vehicle is moving backward, the vehicle control device 1 decreases the target rotational speed by the backward deceleration during deceleration.

[0021] For example, the change amounts (first change amounts) of the forward acceleration and the forward deceleration are the same value. That is, when the vehicle is moving forward, the vehicle control device 1 changes (increases or decreases) the change in the rotational speed until the target rotational speed reaches the value set by the operation of the operation lever 10 by the first change amount. Note that the change amounts of the forward acceleration and the forward deceleration may be different values.

[0022] Furthermore, the amounts of change in reverse acceleration and reverse deceleration are different values. Specifically, the amount of change in reverse acceleration is a second amount of change that is smaller than the first amount of change, and the amount of change in reverse deceleration is the first amount of change. In other words, when accelerating in reverse, the vehicle control device 1 increases the rotational speed by the second amount of change until the target rotational speed reaches a preset rotational speed for reverse, and when decelerating in reverse, it decreases the rotational speed by the first amount of change until the target rotational speed reaches zero. As a result, the vehicle V accelerates more gradually when reversing than when decelerating in reverse or when accelerating or decelerating in forward. Note that the amount of change in reverse is not limited to the first amount of change, but may also be the second amount of change. Alternatively, the amount of change in reverse may be a third amount of change that is smaller than the second amount of change, or larger than the second amount of change (less than the first amount of change). In the following, however, the amount of change in reverse will be assumed to be the first amount of change (the same value as forward acceleration and forward deceleration). In other words, in the following, forward acceleration, forward deceleration, and reverse deceleration will be considered the first variable change, and reverse acceleration will be considered the second variable change, which is smaller than the first variable change.

[0023] In this disclosure, if the vehicle control device 1 receives a switching input to reverse control during deceleration of forward control and the target rotational speed is greater than a threshold, it performs rotational speed control to reduce the target rotational speed by a first change amount until the target rotational speed becomes less than or equal to the threshold.

[0024] Specifically, the vehicle control device 1 switches from forward deceleration to reverse acceleration (or reverse deceleration) if the target rotational speed Rpm is below the threshold TH when a switching input is received via the reverse switch 11 while decelerating with forward deceleration. On the other hand, if the target rotational speed Rpm is greater than the threshold TH, the vehicle control device 1 continues forward deceleration without switching to reverse acceleration.

[0025] In this manner, the vehicle control device 1 decelerates the vehicle using the same first rate of change as before the switch until the target rotational speed Rpm falls below the threshold TH. This prevents the vehicle control device 1 from suddenly switching from the first rate of change to the second rate of change due to a switching input during deceleration, thereby reducing the discomfort experienced by the occupants due to the change in rate of change during deceleration.

[0026] Next, an example of the configuration of the vehicle control device 1 according to the embodiment will be described using Figure 2. Figure 2 is a block diagram showing an example of the configuration of the vehicle control device 1 according to the embodiment. As shown in Figure 2, the vehicle control device 1 is connected to an operating lever 10, a reverse switch 11, a right inverter 20R, and a left inverter 20L.

[0027] The vehicle control device 1 also comprises a controller 2 and a memory unit 3. The controller 2 includes a microcomputer with a CPU (Central Processing Unit), ROM (Read Only Memory), RAM, and various circuits. The controller 2 executes the operation of the entire vehicle control device 1 by having the CPU execute a program stored in the ROM, using the RAM as a working area. The controller 2 may be partially or entirely composed of hardware such as an ASIC (Application Specific Integrated Circuit) or FPGA (Field Programmable Gate Array).

[0028] The storage unit 3 is, for example, RAM (Random Access Memory) or data flash. This storage unit 3 can store control information 31 shown in Figure 1B, information on various programs, and so on. The vehicle control device 1 may also acquire the above-mentioned programs and various information via other computers or portable recording media connected by wired or wireless networks.

[0029] The controller 2 controls the rotational speed of the right motor 14R and the left motor 14L by transmitting control signals to the right inverter 20R and the left inverter 20L in response to operations on the operating lever 10 and the reverse switch 11.

[0030] Specifically, when the reverse switch 11 is not pressed, the controller 2 moves the vehicle V forward by increasing or decreasing the target rotation speed by a first variable amount so that it reaches a rotation speed set according to the tilt angle of the operating lever 10. When the reverse switch 11 is pressed, the controller 2 moves the vehicle V in reverse by increasing or decreasing the target rotation speed by a second variable amount so that it reaches a preset rotation speed.

[0031] Next, Figure 3 will be used to explain the rotational speed control when switching from forward to reverse. Figure 3 is a diagram illustrating the rotational speed control when switching from forward to reverse. In Figure 3, it is assumed that before time t1, the vehicle V is moving forward (operating lever 10 is in the tilted position: accelerator opening is at a predetermined value). In Figure 3, it is assumed that the threshold TH for the target rotational speed described above is zero.

[0032] As shown in Figure 3, let's assume that at time t1, the occupant starts to release the tilted state of the control lever 10 in order to reverse. In this case, the vehicle control device 1 reduces the target rotational speed by the first change amount, which is the forward deceleration, as the accelerator opening decreases. At this time, the actual vehicle speed will begin to decelerate after a predetermined time delay following the start of the decrease in the target rotational speed, due to the vehicle characteristics.

[0033] Next, let's assume that at time t2, the occupant presses the reverse switch 11. At this time, since the target rotational speed is zero or greater (above the threshold TH), the vehicle control device 1 does not switch the amount of change in the target rotational speed to the second amount of change, but continues to use the first amount of change for forward deceleration at time t2.

[0034] Next, let's assume that at time t3, the target rotational speed becomes zero or less. At this time, the vehicle control device 1 switches the amount of change in the target rotational speed from the first amount of change to the second amount of change because the target rotational speed has fallen below the threshold TH. In other words, the vehicle control device 1 switches from forward deceleration to reverse acceleration. As a result, the controller 2 can decelerate the vehicle V using the first amount of change until the vehicle V comes to a stop, and since the amount of change is not switched while the vehicle V is stopping to switch to reverse, the feeling of discomfort with the speed change can be reduced.

[0035] Then, from time t3, the vehicle control device 1 increases the target rotational speed to a preset reverse rotational speed A based on the reverse acceleration. From time t4 onward, the vehicle control device 1 performs rotational speed control to maintain the target rotational speed A until time t5 when the reverse switch 11 is released.

[0036] Then, at time t5, when the reverse switch 11 is released, the vehicle control device 1 switches from reverse acceleration to reverse deceleration to decrease the target rotational speed. Then, at time t6, when the target rotational speed exceeds zero, the vehicle control device 1 switches to forward acceleration to increase the target rotational speed.

[0037] Next, the processing procedure for switching the vehicle control device 1 to reverse according to the embodiment will be described using Figure 4. Figure 4 is a flowchart showing the processing procedure for switching the vehicle control device 1 to reverse according to the embodiment.

[0038] As shown in Figure 3, the controller 2 performs forward control, changing the target rotational speed based on forward acceleration or forward deceleration (step S101). The controller 2 determines whether or not there is a switching input from the reverse switch 11 during forward control (step S102).

[0039] If a switching input is received (step S102: Yes), controller 2 determines whether the target rotational speed at the time the switching input was received is greater than zero (step S103). In step S102, if there is no switching input (step S102: No), controller 2 terminates the process.

[0040] Furthermore, if the target rotational speed is greater than zero (step S103: Yes), the controller 2 decelerates by reducing the target rotational speed with forward deceleration (step S104), and then returns to step S103 to determine if the target rotational speed has become zero.

[0041] Furthermore, in step S103, if the target rotational speed is zero (step S103: No), controller 2 switches from forward deceleration to reverse acceleration, accelerates in the reverse direction (step S105), and terminates the process.

[0042] As described above, the vehicle control device 1 according to the embodiment is a vehicle control device 1 that drives and controls a driving motor 14 attached to a vehicle, and includes a controller 2 that controls the rotational speed of the motor 14 so that it reaches a target rotational speed. The controller 2 decreases the target rotational speed by a first change amount during deceleration in forward control, increases the target rotational speed by a second change amount smaller than the first change amount during acceleration in reverse control, and when switching to reverse control after receiving a switching input from forward control, if the target rotational speed is greater than a threshold, it continues rotational speed control that decreases the target rotational speed by the first change amount.

[0043] According to this disclosure, if the target rotational speed of the motor 14 is greater than a threshold when switching to reverse control, the rotational speed control that reduces the target rotational speed by the first change amount is continued. As a result, when switching to reverse control, if the target rotational speed of the motor 14 is greater than a threshold, deceleration can be continued at the deceleration rate used during forward movement. Therefore, since there is no switch from the first change amount to the second change amount during deceleration while moving forward, the sense of unnaturalness regarding the speed change when switching to reverse can be reduced.

[0044] In the embodiment described above, as shown in Figure 3, an example was shown in which the amount of change in the target rotational speed is switched from the first amount of change (forward deceleration) to the second amount of change (reverse acceleration) when the target rotational speed at time t3 becomes zero. In other words, in Figure 3, the amount of change in the target rotational speed is switched before the actual vehicle speed becomes zero, but the amount of change in the target rotational speed may also be switched after the actual vehicle speed becomes zero. This point will be explained using Figures 5 to 7.

[0045] Figures 5 to 7 illustrate the switching process for the amount of change related to the modified example.

[0046] For example, as shown in Figure 5, the vehicle control device 1 maintains the target rotational speed at zero after it becomes zero, until the actual vehicle speed becomes zero. Specifically, at time t3, the vehicle control device 1 maintains the target rotational speed at zero until time t4, when the actual vehicle speed becomes zero. Then, from time t4, when the actual vehicle speed becomes zero, the vehicle control device 1 increases the target rotational speed using the second variable, which is the reverse acceleration. This allows the vehicle to decelerate using the first variable until the actual vehicle speed becomes zero, thus further reducing the feeling of unnaturalness between switching to reverse and coming to a stop. Note that in Figure 5, the target rotational speed and the actual vehicle speed (actual rotational speed) are shown to be the same from time t4 onwards, but in reality, the actual vehicle speed will increase in the reverse direction with a delay.

[0047] Next, for example, as shown in Figure 6, the vehicle control device 1 may continue to increase the target rotational speed in the reverse direction by the first change amount even after the target rotational speed has become zero, until the actual vehicle speed becomes zero. Specifically, even after the target rotational speed becomes zero at time t3, the vehicle control device 1 increases the target rotational speed in the reverse direction by the same first change amount as the forward deceleration until time t4 when the actual vehicle speed becomes zero. Then, from time t4 when the actual vehicle speed becomes zero, the vehicle control device 1 increases the target rotational speed by the reverse acceleration, which is the second change amount. This makes it possible to shorten the time until the actual vehicle speed becomes zero compared to the case where the target rotational speed is maintained at zero as shown in Figure 3.

[0048] Next, for example, as shown in Figure 7, if the vehicle control device 1 continues to increase the target rotation speed in the reverse direction by a first change amount even after the target rotation speed has reached zero, until the actual vehicle speed reaches zero, an upper limit (deviation tolerance) for the target rotation speed in the reverse direction may be set. Specifically, at time t3, even after the target rotation speed has reached zero, the vehicle control device 1 increases the target rotation speed in the reverse direction by the same first change amount as the forward deceleration until time t4 when the target rotation speed reaches the deviation tolerance B1. Then, if the actual vehicle speed is greater than zero even after the target rotation speed reaches the deviation tolerance B1, the vehicle control device 1 maintains the target rotation speed at the deviation tolerance B1 until time t5 when the actual vehicle speed becomes zero. The deviation tolerance B1 is a value smaller than the target rotation speed A, which is the maximum value in the reverse direction. For example, the deviation tolerance B1 is set to a value closer to zero rotation speed between the target rotation speed A and zero rotation speed. Specifically, the tolerance value B1 is the value obtained by multiplying the target rotational speed A by a coefficient of less than 1 (preferably less than 0.5). Then, from time t5 when the actual vehicle speed becomes zero, the vehicle control device 1 increases the target rotational speed using the second change, which is the reverse acceleration. This makes it possible to avoid the target rotational speed becoming too large in the reverse direction during the period until the actual vehicle speed becomes zero, even when there is a large difference between the target rotational speed and the actual vehicle speed (actual rotational speed). In other words, it is possible to avoid with high precision a situation in which the target rotational speed becomes too large in the reverse direction at time t5 when reverse movement begins, resulting in rapid acceleration in the reverse direction.

[0049] Similarly, the deviation tolerance B2 is also used when switching from reverse to forward. The deviation tolerance B2 is the value of the rotational speed in the forward direction, and for example, the same value as the deviation tolerance B1 is set. Specifically, at time t7, if the reverse switch 11 is released, the vehicle control device 1 reduces the target rotational speed by reverse deceleration. Then, at time t8, if the actual vehicle speed is not zero when the target rotational speed reaches zero, the vehicle control device 1 increases the target rotational speed in the forward direction by the same amount of change as the reverse deceleration. Specifically, the vehicle control device 1 increases the target rotational speed in the forward direction by the same amount of change as the reverse deceleration until the target rotational speed reaches the deviation tolerance B2 or the actual vehicle speed becomes zero. Also, at time t9 when the target rotational speed reaches the deviation tolerance B2, the vehicle control device 1 maintains the target rotational speed at the deviation tolerance B2 because the actual vehicle speed is not zero until time t10 when the actual vehicle speed becomes zero. Then, from time t10 when the actual vehicle speed becomes zero, the vehicle control device 1 increases the target rotational speed using forward acceleration.

[0050] 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 their equivalents. [Explanation of Symbols]

[0051] 1. Vehicle control system 2 Controllers 3 Storage section 10 Operating levers 11 Reverse switch 13L left rear wheel 13R Right rear wheel 14L Left Motor 14R Right Motor 20L Left Inverter 20R Right Inverter 31 Control Information V Vehicle

Claims

1. A vehicle control device that controls the drive of a motor attached to a vehicle, The motor is equipped with a controller that controls the rotational speed so that it reaches a target rotational speed. The aforementioned controller, During deceleration in forward control, the target rotational speed is decreased by a first change, and during acceleration in reverse control, the target rotational speed is increased by a second change that is smaller than the first change. When switching to reverse control is received during the forward control and the system transitions to reverse control, if the target rotational speed is greater than the threshold, the rotational speed control that reduces the target rotational speed by the first change amount is continued. Vehicle control device.

2. The aforementioned controller, The target rotational speed is reduced by the first change amount until the target rotational speed falls below the threshold, and after the target rotational speed falls below the threshold, the target rotational speed is changed by the second change amount. The vehicle control device according to claim 1.

3. The aforementioned threshold is zero, The aforementioned controller, The target rotational speed is decreased by the first amount of change until the target rotational speed becomes zero, and after the target rotational speed reaches zero, the target rotational speed is increased in the reverse direction by the second amount of change. The vehicle control device according to claim 1.

4. The aforementioned controller, After the target rotational speed reaches zero, the target rotational speed is maintained at zero until the vehicle speed reaches zero. After the vehicle speed reaches zero, the target rotational speed is increased in the reverse direction by the second amount of change. The vehicle control device according to claim 3.

5. The aforementioned controller, The target rotational speed is decreased by the first amount of change until it reaches a predetermined value in the reverse direction, and after the target rotational speed reaches the predetermined value in the reverse direction, the target rotational speed is increased in the reverse direction by the second amount of change. The vehicle control device according to claim 1.

6. The aforementioned controller, After the target rotational speed reaches a predetermined value in the reverse direction, the target rotational speed is maintained at the predetermined value until the vehicle speed reaches zero. After the vehicle speed reaches zero, the target rotational speed is increased in the reverse direction by the second amount of change. The vehicle control device according to claim 5.

7. The aforementioned reverse control is, This is a rotational speed control that maintains the maximum value of the predetermined target rotational speed. The predetermined number of rotations is, This value is set between the aforementioned maximum value and zero rotation speed. The vehicle control device according to claim 5.

8. The predetermined number of rotations is, This value is set to be closer to zero rotational speed than the aforementioned maximum value. The vehicle control device according to claim 7.

9. A vehicle control method performed by a vehicle control device that controls the driving motor installed in a vehicle, The motor's rotational speed is controlled so that it reaches the target rotational speed. During deceleration in forward control, the target rotational speed is decreased by a first change, and during acceleration in reverse control, the target rotational speed is increased by a second change that is smaller than the first change. When switching to reverse control is received during the forward control and the system transitions to reverse control, if the target rotational speed is greater than the threshold, the rotational speed control that reduces the target rotational speed by the first change amount is continued. Vehicle control method.

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