Travel control apparatus

Abstract

To provide a travel control apparatus capable of stably braking a vehicle without using a friction brake.SOLUTION: A travel control apparatus 10 gives a vehicle 100 braking power by rotating a left front wheel 110FL and a right front wheel 110FR mutually in reverse directions around respective vertical rotation axes At, or rotating a left rear wheel 110RL and a right rear wheel 110RR mutually in reverse directions around respective vertical rotation axes At.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present invention relates to a cruise control device. [Background technology]

[0002] A driving control device is known that is mounted on a vehicle having a motor for each of the four wheels to provide driving force to the wheels, and that controls the driving force provided to each wheel by controlling the operation of each motor (see, for example, Patent Document 1). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2016-130111 Summary of the Invention

[0004] Vehicles equipped with the above-described conventional cruise control devices are equipped with friction brakes. However, if the vehicle can be stably braked without using friction brakes, there is no need to install friction brakes on the vehicle. Not installing friction brakes on the vehicle can provide various benefits, such as reducing the vehicle's weight.

[0005] An object of the present invention is to provide a driving control device that can stably brake a vehicle without using a friction brake.

[0006] The cruise control device according to the present invention is applied to a vehicle having four wheels, i.e., a left front wheel, a right front wheel, a left rear wheel, and a right rear wheel, each equipped with a motor for applying drive force to each wheel, and controls the drive force applied to each wheel by controlling the operation of the motor. The wheels are mounted on the vehicle so as to be rotatable about vertical rotation axes extending in the vertical direction. The cruise control device according to the present invention is configured to apply a braking force to the vehicle by rotating the left front wheel and the right front wheel in opposite directions about the corresponding vertical rotation axes, or to apply a braking force to the vehicle by rotating the left rear wheel and the right rear wheel in opposite directions about the corresponding vertical rotation axes. Driving control device.

[0007] This allows stable braking of the vehicle without using friction brakes.

[0008] The components of the present invention are not limited to the embodiments of the present invention described below with reference to the drawings. Other objects, features, and attendant advantages of the present invention will be easily understood from the description of the embodiments of the present invention. [Brief explanation of the drawings]

[0009] [Figure 1] FIG. 1(A) is a diagram showing a vehicle equipped with a cruise control device according to an embodiment of the present invention, and FIG. 1(B) is a diagram showing the vehicle when the wheels are turned. [Figure 2] FIG. 2 is a flowchart showing a routine executed by the driving control device according to the embodiment of the present invention. [Figure 3] FIG. 3 is a time chart showing the transition of the driving force etc. when the vehicle is decelerated by the cruise control device according to the embodiment of the present invention. [Figure 4] FIG. 4 is a time chart showing the transition of the driving force and the like when the vehicle is accelerated or decelerated by the cruise control device according to the embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0010] Hereinafter, a cruise control device according to an embodiment of the present invention will be described with reference to the drawings. FIG. 1 shows a cruise control device 10 according to an embodiment of the present invention. The cruise control device 10 is mounted on a vehicle 100. Hereinafter, the cruise control device 10 will be described using as an example a case where the operator of the vehicle 100 is a person who gets on board the vehicle 100 and drives the vehicle 100 (i.e., the driver of the vehicle 100). However, the operator of the vehicle 100 may also be a person who drives the vehicle 100 remotely without getting on board the vehicle 100 (i.e., a remote operator of the vehicle 100).

[0011] As shown in FIG. 1, the driving control device 10 includes an ECU (electronic control unit) 90 as a control device. The ECU 90 includes a microcomputer as a main component. The microcomputer includes a CPU, storage media such as ROM, RAM, and non-volatile memory, as well as an interface. The CPU executes instructions, programs, or routines stored in the storage media to realize various functions. In particular, in this example, the driving control device 10 stores programs in the storage media that realize the various controls executed by the driving control device 10.

[0012] In this example, the driving control device 10 includes only one ECU 90, but it may also be configured to include multiple ECUs, with each ECU performing a different function of the driving control device 10 described below. Also, the driving control device 10 may be configured to be able to update a program stored in a storage medium via wireless communication with an external device (for example, via the Internet).

[0013] The vehicle 100 is equipped with four wheels 110. The four wheels 110 are a pair of front wheels 110F and a pair of rear wheels 110R. The pair of front wheels 110F are a left front wheel 110FL and a right front wheel 110FR. The pair of rear wheels 110R are a left rear wheel 110RL and a right rear wheel 110RR. The vehicle 100 is also equipped with a motor 120 for each wheel 110 that provides driving force to the wheels 110. The motors 120 are electrically connected to the ECU 90.

[0014] In this example, the vehicle 100 is a vehicle in which a larger load is applied to the front wheel 110F than to the rear wheel 110R.

[0015] The cruise control device 10 controls the driving force applied to the wheels 110 by controlling the operation of the motors 120. More specifically, the cruise control device 10 controls the driving force applied to the left front wheel 110FL by controlling the operation of the motor 120 provided corresponding to the left front wheel 110FL, controls the driving force applied to the right front wheel 110FR by controlling the operation of the motor 120 provided corresponding to the right front wheel 110FR, controls the driving force applied to the left rear wheel 110RL by controlling the operation of the motor 120 provided corresponding to the left rear wheel 110RL, and controls the driving force applied to the right rear wheel 110RR by controlling the operation of the motor 120 provided corresponding to the right rear wheel 110RR.

[0016] As shown in FIG. 1B, the wheel 110 is mounted on the vehicle 100 so as to be able to rotate around an axis extending in the vertical direction (vertical rotation axis At). In this example, the vertical rotation axis At is an axis extending in the vertical direction that passes through the intersection of the rotation axis Ar of the wheel 110 and a vertical plane Pv. The vertical plane Pv is a plane perpendicular to the rotation axis Ar and bisects the wheel 110. In this example, the wheel 110 is able to rotate 360° around the vertical rotation axis At.

[0017] In this example, the vehicle 100 is not equipped with a friction brake such as a hydraulic brake or an electric brake.

[0018] Next, the operation of the cruise control device 10 will be described. The cruise control device 10 is configured to execute the routine shown in FIG. 2 at predetermined time intervals. Therefore, at a predetermined timing, the cruise control device 10 starts processing from step S200 of the routine shown in FIG. 2, and proceeds to step S210 to determine whether or not a deceleration request condition C1 is satisfied. The deceleration request condition C1 is a condition that requires deceleration of the vehicle 100. The request to decelerate the vehicle 100 here may be a request from the operator, or may be a request determined by the cruise control device 10 itself based on various information.

[0019] If the cruise control device 10 determines "Yes" in step S210, the process proceeds to step S220, where it determines whether or not an instability condition C2 is established. The instability condition C2 is a condition that, if the driving force applied from the motor 120 to each wheel 110 is reduced in the same manner for all wheels 110, the wheels 110 may slip, causing the behavior of the vehicle 100 to become unstable. The instability condition C2 is, for example, at least one of a condition that the required deceleration of the vehicle 100 is equal to or greater than a predetermined value, and a condition that the friction coefficient of the road surface or ground on which the vehicle 100 is traveling is equal to or less than a predetermined value.

[0020] For example, the instability condition C2 is established when the amount of brake pedal operation by the operator of the vehicle 100 is equal to or greater than a predetermined amount. Alternatively, the instability condition C2 is established when the slip ratio of the wheels 110 acquired based on the acceleration of the vehicle 100 detected by an acceleration sensor and the rotational speed of each wheel 110 detected by a wheel speed sensor is equal to or greater than a predetermined slip ratio. Alternatively, the instability condition C2 is established when an object is detected ahead of the vehicle 100 based on image information ahead of the vehicle 100 acquired by a camera or target information ahead of the vehicle 100 acquired by a laser radar, and it is determined that the vehicle 100 needs to be decelerated at a relatively large deceleration.

[0021] If the determination in step S220 is "Yes," the driving control device 10 proceeds to step S230 to perform the first deceleration control. Next, the driving control device 10 proceeds to step S295 to temporarily end the processing of this routine.

[0022] The first deceleration control is control that performs first driving force control and rear wheel rotation control. The first driving force control is control that gradually reduces the driving force applied from the motor 120 to the front wheel 110F to zero, and simultaneously reduces the driving force applied from the motor 120 to the rear wheel 110R to zero all at once. The rear wheel rotation control is control that applies a braking force to the vehicle 100 by rotating the left rear wheel 110RL, whose vertical plane Pv is parallel to the fore-aft direction of the vehicle 100, counterclockwise by a predetermined angle θp about the vertical rotation axis At corresponding to the left rear wheel 110RL, as shown in FIG. 1B, and rotating the right rear wheel 110RR, whose vertical plane Pv is parallel to the fore-aft direction of the vehicle 100, clockwise by the predetermined angle θp about the vertical rotation axis At corresponding to the right rear wheel 110RR. In this example, the predetermined angle θp is an angle of 90° or less, but may be an angle greater than 90°. Alternatively, the left rear wheel 110RL may be rotated clockwise, and the right rear wheel 110RR may be rotated counterclockwise.

[0023] Therefore, as shown in FIG. 3, when the first deceleration control is started at time t30, the driving force applied to the front wheel 110F is reduced by a predetermined value, and then the driving force is set to zero at time t31. On the other hand, when the first deceleration control is started at time t30, the driving force applied to the rear wheel 110R is set to zero, and rear wheel rotation control is performed. As a result, the speed of the vehicle 100 (vehicle speed) begins to decrease at time t30, and then becomes zero at time t32. Furthermore, at time t33, a predetermined time after time t32, the rear wheel rotation control is ended. As a result, the rear wheel 110R is returned to its original state. That is, the rear wheel 110R is rotated so that the vertical plane Pv related to the rear wheel 110R is parallel to the fore-and-aft direction of the vehicle 100.

[0024] On the other hand, if the determination in step S220 is "No," the driving control device 10 proceeds to step S240 to perform the second deceleration control. Next, the driving control device 10 proceeds to step S295 to temporarily end the processing of this routine.

[0025] The second deceleration control is a control that performs only the second driving force control without performing the rear wheel rotation control. The second driving force control is a control that reduces the driving force applied from the motor 120 to the front wheels 110F and the rear wheels 110R to zero in one go.

[0026] If the determination in step S210 is "No," the driving control device 10 proceeds to step S250, where normal driving force control is performed. Next, the driving control device 10 proceeds to step S295, where the processing of this routine is temporarily ended.

[0027] The normal driving force control is a control in which the motor 120 applies a driving force corresponding to the target driving force to the front wheels 110F and the rear wheels 110R to make the vehicle 100 travel.

[0028] The above is the operation of the cruise control device 10. According to the cruise control device 10, when deceleration of the vehicle 100 is likely to cause the behavior of the vehicle 100 to become unstable, the vehicle 100 is decelerated by the first deceleration control. Therefore, the vehicle 100 can be stably braked without using a friction brake.

[0029] The present invention is not limited to the above-described embodiment, and various modifications can be made within the scope of the present invention.

[0030] For example, when controlling the speed of the vehicle 100 to a target speed, the cruise control device 10 may be configured to control the driving force applied to each wheel 110, as shown in FIG. 4. In the example shown in FIG. 4, when an acceleration request condition C3 is met at time t40, indicating that acceleration of the vehicle 100 is requested, the driving force applied to the front wheels 110F and the rear wheels 110R is increased by a first value. This increases the speed of the vehicle 100. Note that rear wheel rotation control is not performed at this time. Then, when the speed of the vehicle 100 reaches the target speed at time t41, the driving force applied to the front wheels 110F and the rear wheels 110R is reduced by a second value smaller than the first value. This maintains the speed of the vehicle 100 at the target speed.

[0031] On the other hand, at time t42, when the deceleration request condition C1 is met, the driving force applied to the front wheels 110F and rear wheels 110R is suddenly set to zero, and rear wheel rotation control is implemented. This causes the speed of the vehicle 100 to decrease. Then, at time t43, when the speed of the vehicle 100 reaches the target speed, the rear wheel rotation control is ended, and the driving force applied to the front wheels 110F and rear wheels 110R is increased by a predetermined value. This causes the speed of the vehicle 100 to be maintained at the target speed.

[0032] Alternatively, the first deceleration control may be a control that rotates each motor 120 in the reverse direction to greatly increase the braking force applied to the front wheel 110F and gradually increase the braking force applied to the rear wheel 110R.

[0033] Furthermore, the above-described embodiment is based on the premise that vehicle 100 is a vehicle in which a greater load is applied to front wheel 110F than to rear wheel 110R. However, the present invention is also applicable to vehicles in which a greater load is applied to rear wheel 110R than to front wheel 110F. In this case, the first driving force control of the first deceleration control is control that reduces the driving force applied from motor 120 to front wheel 110F to zero in one go, and that reduces the driving force applied from motor 120 to rear wheel 110R gradually to zero. In this case, the first deceleration control is control that performs front wheel rotation control instead of rear wheel rotation control. The front wheel rotation control is a control that applies a braking force to the vehicle 100 by rotating the left front wheel 110FL, whose vertical plane Pv is parallel to the fore-and-aft direction of the vehicle 100, counterclockwise by a predetermined angle θp around the vertical rotation axis At corresponding to the left front wheel 110FL, and by rotating the right front wheel 110FR, whose vertical plane Pv is parallel to the fore-and-aft direction of the vehicle 100, clockwise by the above-mentioned predetermined angle θp around the vertical rotation axis At corresponding to the right front wheel 110FR.

[0034] The present invention is also applicable to vehicles that can be driven by both manual driving operations and automatic driving control, vehicles that are driven only by manual driving operations, and vehicles that are driven only by automatic driving control. [Explanation of symbols]

[0035] 10...cruise control device, 90...ECU, 100...vehicle, 110FL...left front wheel, 110FR...right front wheel, 110RL...left rear wheel, 110RR...right rear wheel, 120...motor

Claims

[Claim 1] A driving control device is applied to a vehicle having four wheels, i.e., a left front wheel, a right front wheel, a left rear wheel, and a right rear wheel, each of which is provided with a motor for applying a driving force to each of the wheels, and controls the operation of the motor to control the driving force applied to the wheels, the wheels are provided on the vehicle so as to be rotatable about vertical rotation axes extending in a vertical direction, The driving control device includes: applying a braking force to the vehicle by rotating the left front wheel and the right front wheel in opposite directions about the corresponding vertical rotation axes, or applying a braking force to the vehicle by rotating the left rear wheel and the right rear wheel in opposite directions about the corresponding vertical rotation axes; It is configured as follows: Driving control device.

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