A power differential steering system and control method for a four-wheel independent drive vehicle

Abstract

The application relates to a power differential steering system and a control method of a four-wheel independent drive vehicle, wherein the power differential steering system comprises four wheels, four driving mechanisms, four controllers and a general controller; the four driving mechanisms are respectively in driving connection with the four wheels; the four controllers are respectively connected with the four driving mechanisms, and the four controllers respectively control the four driving mechanisms; the general controller is connected with the four controllers, controls the four controllers, and the general controller has different power differential steering control modes according to the vehicle speed. The system can independently drive the vehicle to realize large differential steering, the steering performance is superior to that of other vehicles, the turning radius is small, the vehicle center steering can be realized, the inside and outside of the vehicle can be uniformly steered, the stable steering of the vehicle in a high-speed state can be realized, the vehicle can be prevented from overturning during high-speed steering, the steering advantages of the four-wheel independent drive vehicle are fully exerted, and the steering, stability and safety of the vehicle are effectively improved.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of vehicle steering control, in particular to a four-wheel independent drive vehicle power difference steering system and a control method. BACKGROUND

[0002] The four-wheel independent drive vehicle is connected with four motors respectively to four wheels, the four wheels can provide reliable steering power, and the power of the left and right wheels can be different, that is, power difference. Each wheel torque is independently controllable and measurable, torque response is rapid and accurate, and has strong power, especially suitable for driving of UTV (multi-functional all-terrain vehicle). Therefore, the torque output on a single wheel can be changed in time according to the needs, effectively improving the maneuverability, stability and safety of the vehicle.

[0003] The four-wheel independent drive vehicle power difference steering system in the prior art can only steer within the allowable range of power difference, resulting in a large turning radius, and the steering advantage of the four-wheel independent drive vehicle cannot be fully utilized. SUMMARY

[0004] To solve the above problems, the present application provides a four-wheel independent drive vehicle power difference steering system and a control method, which takes different speeds of the vehicle as the basis to perform three power difference steering controls, and the torque values of each power difference steering control are different, so as to fully utilize the steering performance of the four-wheel independent drive vehicle, break through the structure of the vehicle itself and the determination of Ackerman steering radius by steering wheel angle, achieve a small turning radius, including steering around the geometric center of the vehicle, and fully utilize the steering advantage of the four-wheel independent drive vehicle.

[0005] Specifically, the technical scheme includes the following:

[0006] In one aspect, the present application provides a four-wheel independent drive vehicle power difference steering system, comprising:

[0007] four wheels;

[0008] four drive mechanisms respectively drivingly connected with the four wheels;

[0009] four controllers respectively connected with the four drive mechanisms, the four controllers respectively controlling the four drive mechanisms; and

[0010] a general controller connected with the four controllers and controlling the four controllers, the general controller having different power difference steering control modes according to vehicle speed.

[0011] In some embodiments, the power difference steering control modes include a low-speed zone power difference steering control mode, a medium-speed zone power difference steering control mode and a high-speed zone power difference steering control mode.

[0012] The power difference steering control mode is based on a vehicle body center speed V that satisfies the following relationship:

[0013]

[0014] wherein the four wheels include a first wheel, a second wheel, a third wheel, and a fourth wheel, the four driving mechanisms include a first driving mechanism, a second driving mechanism, a third driving mechanism, and a fourth driving mechanism; v1, v2, v3, and v4 are the rotational speeds of the first wheel, the second wheel, the third wheel, and the fourth wheel, respectively; O is the instantaneous rotation center of the vehicle; R is the distance between the midpoint of the rear axle of the vehicle and the instantaneous rotation center O; L is the wheelbase; B is the track; a is the steering angle of the wheels; and the value of the vehicle body center speed V is the total scalar value corresponding to the superposition of the four wheel speed vectors.

[0015] In some embodiments, the control torque value distribution of the low-speed zone power difference steering control mode satisfies the following relationship:

[0016]

[0017] wherein T1, T2, T3, and T4 are the torque values of the first driving mechanism, the second driving mechanism, the third driving mechanism, and the fourth driving mechanism, respectively; γ is the steering angle of the vehicle steering wheel; β is the angle of the vehicle accelerator pedal; and T is the total torque value of the vehicle.

[0018] In some embodiments, the control torque value distribution of the medium-speed zone power difference steering control mode satisfies the following relationship:

[0019]

[0020] wherein T1, T2, T3, and T4 are the torque values of the first driving mechanism, the second driving mechanism, the third driving mechanism, and the fourth driving mechanism, respectively; γ is the steering angle of the vehicle steering wheel; β is the angle of the vehicle accelerator pedal; and T is the total torque value of the vehicle.

[0021] In some embodiments, the control torque value distribution of the high-speed zone power difference steering control mode satisfies the following relationship:

[0022]

[0023] wherein T1, T2, T3, and T4 are the torque values of the first driving mechanism, the second driving mechanism, the third driving mechanism, and the fourth driving mechanism, respectively; γ is the steering angle of the vehicle steering wheel; β is the angle of the vehicle accelerator pedal; and T is the total torque value of the vehicle.

[0024] In some embodiments, a reducer is further included, the driving mechanism is connected with the reducer, a half shaft is connected with the reducer, and the half shaft is connected with a wheel through a constant velocity universal joint.

[0025] In some embodiments, a power battery is further included for providing electric energy for the vehicle, the power battery is connected with the general controller, and the general controller controls the four controllers and manages the power battery through a CAN line.

[0026] In some embodiments, the driving mechanism is an electric motor.

[0027] In another aspect, the application provides a control method based on the four-wheel independent driving vehicle power differential steering system, comprising:

[0028] acquiring a power differential steering control mode determined by the general controller according to the vehicle body center speed;

[0029] allocating an output torque value of each driving mechanism in an operating state through each controller;

[0030] making each driving mechanism work according to the allocated output torque value.

[0031] In some embodiments, the power differential steering control mode includes a low-speed zone power differential steering control mode, a medium-speed zone power differential steering control mode and a high-speed zone power differential steering control mode.

[0032] Based on the above technical solution, the four-wheel independent driving vehicle power differential steering system of one embodiment of the application can independently drive the vehicle to realize large differential steering, provide another motion function for vehicle maneuvering, has better steering performance than other vehicles, has a small turning radius, can avoid accidents and facilitate steering motion; can fully exert the steering performance of the four-wheel independent driving vehicle, can break through the structure of the vehicle itself and the determination of Ackerman steering radius by steering wheel angle, and achieve a small turning radius. Three power differential steering control modes are determined based on the vehicle body center speed, the vehicle body center speed is a total scalar value corresponding to the superposition of the speed vectors of the four wheels, can better reflect the actual speed of the vehicle, and makes the four-wheel independent driving vehicle speed judgment more accurate. In the low-speed zone power differential steering control mode, the vehicle center can be steered; in the medium-speed zone power differential steering control mode, the inside and outside of the vehicle can be uniformly steered; in the high-speed zone power differential steering control mode, the vehicle can be stably steered in the inside at a low speed in a high-speed state, preventing the vehicle from rolling laterally when steering at high speed; the steering advantage of the four-wheel independent driving vehicle is fully exerted, the vehicle can be stably and efficiently steered, and the maneuverability, stability and safety of the vehicle are effectively improved. BRIEF DESCRIPTION OF DRAWINGS

[0033] The accompanying drawings, which are included to provide a further understanding of the application and are incorporated in and constitute a part of this application, illustrate embodiments of the application and together with the description serve to explain the application. In the drawings:

[0034] Figure 1 Structure diagram of an embodiment of the power difference steering system of the four-wheel independent drive vehicle of the present application.

[0035] Figure 2 Structure diagram of an embodiment of the power difference steering system of the four-wheel independent drive vehicle of the present application.

[0036] Figure 3 Structure diagram of an embodiment of the power difference steering system of the four-wheel independent drive vehicle of the present application.

[0037] Figure 4 Structure diagram of an embodiment of the power difference steering system of the four-wheel independent drive vehicle of the present application.

[0038] BRIEF DESCRIPTION OF DRAWINGS 11, first wheel; 12, second wheel; 13, third wheel; 14, fourth wheel; 21, first drive mechanism; 22, second drive mechanism; 23, third drive mechanism; 24, fourth drive mechanism; 31, first controller; 32, second controller; 33, third controller; 34, fourth controller; 4, general controller; 5, power battery; 6, speed reducer; 7, half shaft; 8, constant velocity universal joint; 9, accelerator pedal; 10, steering wheel. DETAILED DESCRIPTION

[0039] The present application is described below in detail. In the following paragraphs, different aspects of the embodiments are defined more particularly. Each aspect thus defined can be combined with any other aspect or aspects, unless explicitly stated otherwise. In particular, any feature described as preferred or advantageous can be combined with any other feature or features described as preferred or advantageous.

[0040] The terms "first", "second", etc. appearing in the present application are only for the convenience of description, to distinguish different components with the same name, and do not represent the order or primary and secondary relationship.

[0041] In addition, when an element is referred to as being "on" another element, it can be directly on the other element or indirectly on the other element with one or more intervening elements therebetween. Also, when an element is referred to as being "connected to" another element, it can be directly connected to the other element or indirectly connected to the other element with one or more intervening elements therebetween. Hereinafter, like reference numerals refer to like elements.

[0042] The descriptions of the directions or positional relationships indicated by "upper", "lower", "top", "bottom", "front", "back", "inner" and "outer" in the present application are only for the convenience of describing the present application, and are not intended to indicate or imply that the devices referred to must have a particular orientation, be constructed and operated in a particular orientation, and therefore cannot be understood as limiting the scope of protection of the present application.

[0043] As shown in Figure 1 The present application provides a four-wheel independent drive vehicle power differential steering system, which in some embodiments includes four wheels, four drive mechanisms, four controllers and a general controller 4; the four drive mechanisms are respectively drivingly connected with the four wheels, and the four wheels are independently driven; the four controllers are respectively connected with the four drive mechanisms, and the four controllers respectively control the four drive mechanisms; the general controller 4 is connected with the four controllers to control the four controllers, and the general controller 4 has different power differential steering control modes according to the vehicle speed.

[0044] Among them, the four wheels include a first wheel 11 located at the front left of the vehicle, a second wheel 12 located at the rear left of the vehicle, a third wheel 13 located at the rear right of the vehicle, and a fourth wheel 14 located at the front right of the vehicle; the four drive mechanisms include a first drive mechanism 21 drivingly connected with the first wheel 11, a second drive mechanism 22 drivingly connected with the second wheel 12, a third drive mechanism 23 drivingly connected with the third wheel 13, and a fourth drive mechanism 24 drivingly connected with the fourth wheel 14; the four controllers include a first controller 31 connected with the first drive mechanism 21, a second controller 32 connected with the second drive mechanism 22, a third controller 33 connected with the third drive mechanism 23, and a fourth controller 34 connected with the fourth drive mechanism 24.

[0045] The embodiment of the present application adopts a four-wheel independent drive distributed drive structure, and the four wheels can provide reliable steering power, and the power of the wheels on the left and right sides can be different, i.e. power differential. Each wheel torque is independently controllable and measurable, torque response is rapid and accurate, and has extremely strong power, and is especially suitable for driving of a UTV (multi-functional all-terrain vehicle). Therefore, the torque output on a single wheel can be changed in time according to needs, and the maneuverability, stability and safety of the vehicle are effectively improved.

[0046] In some embodiments, a speed reducer 6 is further included, the output end of the drive mechanism is connected with the input end of the speed reducer 6, the output end of the speed reducer 6 is connected with a half shaft 7, and the half shaft 7 is connected with the wheel through a constant velocity universal joint 8. The drive mechanism drives the speed reducer 6 to operate, and the speed reducer 6 is connected with the wheel through the half shaft 7 and the constant velocity universal joint 8, so as to realize that the drive mechanism drives the wheel to rotate. The speed reducer 6 can lengthen the half shaft 7, so that the length of the vehicle suspension is larger.

[0047] In some embodiments, a power battery 4 is further included for providing electric energy for the vehicle, the power battery 4 is connected with a general controller 5, the general controller 5 controls the four controllers through a CAN line (controller area network bus) to realize four-wheel independent driving and steering motor, and the general controller 5 simultaneously manages the power battery 4.

[0048] In some embodiments, the driving mechanism is an electric motor.

[0049] In some embodiments, the power difference steering control mode includes a low-speed zone power difference steering control mode, a medium-speed zone power difference steering control mode and a high-speed zone power difference steering control mode.

[0050] As shown in Figure 2 , the power difference steering control mode is based on a vehicle body center speed V satisfying the following relationship:

[0051]

[0052] Wherein, v1, v2, v3 and v4 are the rotation speeds of the first wheel, the second wheel, the third wheel and the fourth wheel respectively, the rotation speed of the wheel is measured by the reduction ratio of the speed reducer 6 through the speed sensor; O is the instantaneous rotation center of the vehicle; R is the distance between the midpoint of the rear axle of the vehicle and the instantaneous rotation center O; L is the wheelbase of the vehicle; B is the track of the vehicle; α is the steering angle of the wheel; the value of the vehicle body center speed V is the total scalar value corresponding to the superposition of the four wheel speed vectors, and the application is based on the vehicle body center speed, which can better reflect the real speed of the vehicle, so that the four-wheel independent driving speed judgment is more accurate.

[0053] As shown in Figure 2 , 3 and 4, when the steering angle α is equal to 0, that is, the vehicle is driving straight, the general controller 5 evenly distributes the power of the four motors, that is, the angle of the accelerator pedal 9 is β (0≤β≤1) (wherein, when β=0, it represents that the power output of the vehicle is 0%; when β=1, it represents that the power output of the vehicle is 100%), the corresponding total torque value T, then the torque values T1, T2, T3 and T4 corresponding to the first driving mechanism 21, the second driving mechanism 22, the third driving mechanism 23 and the fourth driving mechanism 24 are equal, and T=T1+T2+T3+T4, or T=T1×4, the vehicle drives straight. When the steering wheel 10 rotates, the steering angle of the steering wheel 10 is 0~γ, corresponding to the steering angle of the wheel 0~α. Taking the left turn of the vehicle as an example, at this time α is positive, and α is negative when turning right.

[0054] In some embodiments, the low-speed power difference steering control mode is applicable to the control mode of low-speed off-road, and the present application takes a UTV (multi-purpose all-terrain vehicle) as an example. When the center speed of the vehicle body V is less than or equal to 25 km / h, the angle of the accelerator pedal 9 is β, and the steering angle of the steering wheel 10 is γ, the control torque value distribution of the low-speed power difference steering control mode satisfies the following relationship:

[0055]

[0056] In the low-speed power difference steering control mode, steering around the geometric center of the vehicle can be realized.

[0057] In some embodiments, the medium-speed power difference steering control mode is applicable to the control mode of medium-speed, and the present application takes a UTV (multi-purpose all-terrain vehicle) as an example. When the center speed of the vehicle body V is greater than 25 km / h and less than 65 km / h, i.e. 25 km / h < v ≤ 65 km / h, the angle of the accelerator pedal 9 is β, and the steering angle of the steering wheel 10 is γ, the control torque value distribution of the medium-speed power difference steering control mode satisfies the following relationship:

[0058]

[0059] In the medium-speed power difference steering control mode, the inside and outside of the vehicle can be uniformly steered when the vehicle is steered.

[0060] In some embodiments, the high-speed power difference steering control mode is applicable to the control mode of high-speed, and the present application takes a UTV (multi-purpose all-terrain vehicle) as an example. When the center speed of the vehicle body V is greater than 65 km / h, the angle of the accelerator pedal 9 is β, and the steering angle of the steering wheel 10 is γ, the control torque value distribution of the high-speed power difference steering control mode satisfies the following relationship:

[0061]

[0062] In the high-speed power difference steering control mode, stable steering of the vehicle in the high-speed state can be realized to prevent the vehicle from overturning when steering at high speed.

[0063] The above takes the left turn of the vehicle as an example, and γ is positive at this time, and γ is negative when turning right.

[0064] It should be noted that the specific value range of the low-speed, medium-speed and high-speed of the vehicle in the above power difference steering control mode of the present application can be adjusted according to different vehicle models, and no specific limitation is made.

[0065] Finally, the present application also provides a control method of the above-mentioned four-wheel independent drive vehicle power difference steering system. In some embodiments, the control method comprises:

[0066] Step 101, acquiring a power difference steering control mode determined by the total controller according to the vehicle body center vehicle speed;

[0067] Step 102, distributing the output torque value of each drive mechanism in the working state by each controller;

[0068] Step 103, making each drive mechanism work according to the distributed output torque value.

[0069] Steps 101-103 are sequentially executed, this embodiment selects a suitable power difference steering control mode according to the vehicle body center vehicle speed, adopts a distributed drive structure of four-wheel independent drive, four wheels can provide reliable steering power, and the power of the left and right wheels can be different, that is, power difference. Each wheel torque is independently controllable and measurable, torque response is rapid and accurate, has very strong power, and is especially suitable for UTV (multi-purpose all-terrain vehicle) drive, can timely change the torque output on a single wheel according to the need, and effectively improve the maneuverability, stability and safety of the vehicle.

[0070] Specifically, the power difference steering control mode includes: a low-speed zone power difference steering control mode, a medium-speed zone power difference steering control mode and a high-speed zone power difference steering control mode.

[0071] The loader power system and its control method and the loader provided by the present application are described in detail above. The principles and implementation modes of the present application are described by applying specific embodiments in this paper, and the above embodiment description is only used to help understand the method of the present application and its core idea. It should be pointed out that for ordinary skilled persons in the technical field, some improvements and modifications can be made to the present application without departing from the principles of the present application, and these improvements and modifications also fall within the protection scope of the claims of the present application.

Claims

1. A power-differential steering system for a four-wheel independent drive vehicle, characterized by, Comprise: Four wheels; Four driving mechanisms, respectively drivingly connected with the four wheels; Four controllers, respectively connected with the four driving mechanisms, the four controllers respectively controlling the four driving mechanisms; And A general controller, connected with the four controllers, controlling the four controllers, the general controller having different power difference steering control modes according to vehicle speed; The power difference steering control modes comprise: a low-speed zone power difference steering control mode, a medium-speed zone power difference steering control mode and a high-speed zone power difference steering control mode; The power difference steering control modes are based on vehicle body center speed, and the vehicle body center speed V satisfies the following relationship: The four driving mechanisms include a first driving mechanism, a second driving mechanism, a third driving mechanism and a fourth driving mechanism; 、 、 and are the rotating speeds of the first wheel, the second wheel, the third wheel and the fourth wheel respectively; O is the instantaneous rotating center of the vehicle; R is the distance between the midpoint of the rear axle of the vehicle and the instantaneous rotating center O; L is the wheelbase; B is the track; is the steering angle of the wheel; the value of the vehicle body center speed V is the total scalar value corresponding to the superposition of the four wheel speed vectors. The control torque value distribution of the low-speed zone power difference steering control mode satisfies the following relationship: wherein T1, T2, T3 and T4 are torque values of the first driving mechanism, the second driving mechanism, the third driving mechanism and the fourth driving mechanism, respectively, is an angle of rotation of a steering wheel of the vehicle; is an angle of an accelerator pedal of the vehicle; and T is a total torque value of the vehicle.

2. The four-wheel independent drive vehicle power differential steering system according to claim 1, characterized by, The control torque value distribution of the high-speed zone power difference steering control mode satisfies the following relationship: wherein T1, T2, T3 and T4 are torque values of the first driving mechanism, the second driving mechanism, the third driving mechanism and the fourth driving mechanism, respectively, is an angle of rotation of a steering wheel of the vehicle; is an angle of an accelerator pedal of the vehicle; and T is a total torque value of the vehicle.

3. The four-wheel independent drive vehicle power differential steering system of claim 1, wherein, Further comprise a speed reducer, the driving mechanism is connected with the speed reducer, the speed reducer is connected with half shaft, the half shaft is connected with the wheel through the constant velocity universal joint.

4. The four-wheel independent drive vehicle power differential steering system of claim 1, wherein, Further comprise a power battery for providing electric energy for the vehicle, the power battery is connected with the general controller, the general controller controls the four controllers and manages the power battery through CAN line.

5. The four-wheel independent drive vehicle power differential steering system of claim 1, wherein, The driving mechanism is a motor.

6. A control method for a power differential steering system of a four-wheel independent drive vehicle according to any one of claims 1 to 5, characterized by Comprise: Obtaining the power difference steering control mode determined by the general controller according to the vehicle body center speed; Through each controller, distributing the output torque value of each driving mechanism in working state; Make each driving mechanism work according to the distributed output torque value.

7. The control method according to claim 6, characterized by The power difference steering control modes comprise: a low-speed zone power difference steering control mode, a medium-speed zone power difference steering control mode and a high-speed zone power difference steering control mode.

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