A high-efficiency in-place steering vehicle structure of a four-wheel hybrid gear train and a control method thereof

Abstract

The application discloses a kind of four-wheel hybrid wheel train high-efficiency spot steering vehicle structure and control method thereof, including vehicle body, front wheel system, rear wheel system, front suspension system, drive system and vehicle control unit VCU;The front wheel system, rear wheel system is respectively installed in vehicle body front axle, rear axle, the front suspension system is connected with front wheel system, the drive system is assembled in rear axle and drives rear wheel system operation, the vehicle control unit VCU VCU is electrically connected with drive system, steering function full coverage, field adaptability is extremely strong: rely on front and rear heterogeneous hybrid wheel train structure, can realize conventional straight, small radius differential steering, single rear wheel fixed-point steering, rear wheel interval eccentric steering, whole vehicle geometric center global spot self-rotation five kinds of motion modes, completely get rid of Ackerman mechanism minimum turning radius limit, perfect adaptation factory area, greenhouse, mountain, reservoir narrow operation scene, greatly improve the maneuverability of operation vehicle.

Description

Technical Field

[0001] This invention relates to the field of intelligent mobile vehicle steering-related products, specifically to a high-efficiency stationary steering vehicle structure and its control method for a four-wheel hybrid wheel system. Background Technology

[0002] Traditional civilian work vehicles, site mobility vehicles, and park work vehicles generally adopt Ackermann steering geometry, which relies on the mechanical deflection of the front wheels to achieve the turning of the whole vehicle. This inherent steering structure has a fixed and relatively large turning radius, making it impossible to complete turning around or moving the vehicle in place in narrow working spaces such as narrow factory areas, forest plots, greenhouse fields, and enclosed warehouse areas. The vehicle's maneuverability is extremely poor.

[0003] Currently, the industry mainly uses two mainstream technical solutions to achieve extremely small turning radius on the spot for vehicles. Both solutions have unavoidable application shortcomings:

[0004] The first category is tracked vehicles, which rely on the differential rotation of the tracks on the left and right sides of the vehicle body to achieve self-rotation and steering. However, their integrated track structure has a large self-weight, high rolling resistance, high energy consumption, complex mechanical transmission structure, high daily maintenance costs, and limited speed on flat roads. They are only suitable for heavy off-road scenarios and cannot be adapted to lightweight low-speed commuting or light-duty operation scenarios.

[0005] The second category is intelligent vehicles with four-wheel independent drive and four-wheel independent steering. Each set of wheels is independently equipped with a steering motor, drive motor, and dedicated suspension. It can achieve multiple sports modes such as 90° wheel deflection, crab movement, and all-area stationary steering. However, the integration of the vehicle's electronic control system and mechanical suspension is extremely high, the procurement cost of wheel hub motors and steering actuators is high, the complexity of the vehicle control algorithm is high, the anti-interference ability is weak, the failure rate on harsh unpaved roads is high, and lightweight, low-cost operation models cannot be industrialized.

[0006] In addition, the two existing types of simple in-situ steering derivative technologies also have obvious drawbacks:

[0007] Existing simple braking differential steering technology: By hydraulically or mechanically locking one side of the rear wheel, power is distributed to the other side of the wheel through the vehicle's differential to achieve steering around the rear wheel. In this scheme, the front wheels are ordinary solid / pneumatic tires with no lateral slip capability. When steering, the front wheels are forced to scrape the ground, resulting in extremely high lateral slip resistance, doubling the tire wear rate, causing severe ground crushing damage, and causing the steering center to shift and float, resulting in poor control precision and the inability to achieve the vehicle's geometric center to rotate in place.

[0008] Existing front-mounted single swivel wheel steering technology: The front-mounted ordinary single swivel wheel is combined with the rear wheel differential steering. The swivel wheel has a gap in grounding and poor grounding stability, resulting in large steering vibration and weak load-bearing capacity. Under heavy load conditions, the swivel wheel will jam and cannot slide laterally. It is only suitable for micro-sized unloaded robots and cannot be used for vehicles carrying people or goods.

[0009] In summary, the industry currently lacks a four-wheel vehicle structure that combines low cost, low wear, low energy consumption, high reliability, and Ackermann-free steering, enabling multi-level on-the-spot steering. Based on this, this invention proposes a highly efficient on-the-spot steering vehicle structure and its control method for a four-wheel hybrid wheel system. Summary of the Invention

[0010] The purpose of this invention is to provide a highly efficient vehicle structure for stationary steering with a four-wheel hybrid wheel system and its control method, so as to solve the problems mentioned in the background art.

[0011] To achieve the above objectives, the present invention provides the following technical solution: a high-efficiency vehicle structure for stationary steering with a four-wheel hybrid wheel system, comprising a vehicle body, a front wheel system, a rear wheel system, a front suspension system, a drive system, and a vehicle control unit (VCU);

[0012] The front wheel system and the rear wheel system are respectively installed on the front axle and the rear axle of the vehicle body. The front suspension system connects the vehicle body and the front wheel system. The drive system is installed on the rear axle and drives the rear wheel system to rotate. The vehicle control unit (VCU) is electrically connected to the drive system.

[0013] The front wheel system includes symmetrically arranged left front split omnidirectional wheels and right front split omnidirectional wheels. Each split omnidirectional wheel consists of two independent wheel bodies that are coaxially mounted and have staggered roller phases. Each wheel body has freely rotating rollers evenly distributed around its circumference. The angle between the roller axis and the wheel axle axis satisfies the formula: Angle = 360° ÷ Number of rollers per wheel ÷ 2. After the two wheel bodies are assembled, they form a seamless, circular grounding structure perpendicular to the wheel axle direction.

[0014] The rear wheel system includes a symmetrically arranged left rear pneumatic tire and a right rear pneumatic tire, both of which are standard automotive rubber pneumatic tires.

[0015] The front suspension system adopts a parallel four-link independent suspension with equal upper and lower rocker arms, which is used to constrain the split-type all-around wheel to always be perpendicular to the vehicle body when it bounces.

[0016] The drive system is a dual-motor independent drive structure, including a left rear drive motor and a right rear drive motor. The left rear drive motor and the right rear drive motor drive the left rear pneumatic tire and the right rear pneumatic tire respectively. The vehicle eliminates the Ackermann steering mechanism and achieves vehicle steering by relying on the lateral slip of the front wheels and the speed difference of the rear wheels.

[0017] As a preferred embodiment of the present invention, the angle between the roller axis and the wheel axle axis of the single-component omnidirectional wheel is in the range of 45°~90°, and the two independent wheel rollers are installed with staggered phase angles to ensure that there are no less than two grounding points.

[0018] A highly efficient stationary steering control method for a four-wheel hybrid wheel system is proposed. This method relies on the vehicle control unit (VCU) to collect accelerator pedal opening α and steering wheel angle β to achieve graded steering control. The accelerator pedal opening α ranges from 0 to 100%. Left steering is defined as a positive angle, and right steering as a negative angle. A steering coefficient γ is set, where γ = current steering wheel deflection / maximum steering wheel deflection. The baseline straight-line speed is V. The specific control steps are as follows:

[0019] S1, Straight Driving Condition: The steering wheel is centered with no deflection, γ=0, the vehicle control unit (VCU) controls the speed of the left rear drive motor V1 and the speed of the right rear drive motor V2 to satisfy V1=V2=V, and the whole vehicle travels straight at a constant speed.

[0020] S2, Small-angle differential steering condition: The steering wheel is turned to one side, and 0 < γ < 0.5. Taking left turn as an example, the vehicle control unit (VCU) regulates the speed of the left rear drive motor V1 = V(1-2γ), while the right rear drive motor keeps the speed V2 = V constant. The small-radius left turn is achieved by relying on the lateral slip of the front wheels.

[0021] S3, Single rear wheel fixed-point steering condition: The steering wheel is turned to one side and γ=0.5. Taking left turn as an example, the vehicle control unit VCU adjusts the speed of the left rear drive motor V1=0, while the right rear drive motor keeps the speed V2=V unchanged. The whole vehicle turns left in place around the contact point of the left rear inflatable tire.

[0022] S4, Fixed-point turning condition within the wheel track range: The steering wheel is turned to one side, and 0.5 < γ < 1. Taking left turn as an example, the vehicle control unit (VCU) adjusts the reverse speed of the left rear drive motor to V1 = -V(2γ-1), while the right rear drive motor keeps the speed V2 = V constant. The whole vehicle turns left in place around the inner interval of the left and right rear wheel track.

[0023] S5, Vehicle geometric center stationary turning condition: The steering wheel is turned to the maximum opening, γ=1. Taking left turn as an example, the vehicle control unit (VCU) adjusts the left rear drive motor to reverse speed V1=-V, while the right rear drive motor keeps the speed V2=V unchanged. The vehicle completes stationary center turning around the geometric center of the rear wheel track.

[0024] As a preferred embodiment of the present invention, during vehicle steering, the parallel four-link independent suspension constrains the verticality of the split-type all-around wheels in real time, counteracting the wheel deflection angle caused by vehicle pitch and roll, and ensuring that the rollers slide freely in contact with the ground.

[0025] Compared with the prior art, the beneficial effects of the present invention are:

[0026] 1. Full coverage of steering functions and strong adaptability to various sites: Relying on the front and rear heterogeneous hybrid wheel system structure, it can realize five types of motion modes: conventional straight driving, small radius differential steering, single rear wheel fixed point steering, rear wheel interval eccentric steering, and full-range stationary rotation of the vehicle's geometric center. It completely gets rid of the minimum turning radius limitation of the Ackermann mechanism, perfectly adapts to narrow working scenarios such as factory areas, greenhouses, mountains, and warehouses, and greatly improves the mobility of the working vehicle.

[0027] 2. The mechanical structure is extremely simple, and the overall vehicle cost is greatly reduced: There is no need to configure four-wheel steering motors, steering suspensions, and steering transmission rods. Only the front axle wheel body and suspension structure are modified. The rear axle can use a traditional rear axle, a dual-motor rear axle, or a common differential rear axle. The number of parts is reduced by more than 40%, and the production and maintenance costs are far lower than those of four-wheel independent steering vehicles, making it suitable for low-speed mass production models.

[0028] 3. Extremely low steering wear and longer service life: The front wheel split all-around wheel has omnidirectional passive slip capability. There is no hard tire scrubbing or crushing behavior during the steering process. Compared with ordinary front wheel braking and steering system, tire wear is reduced by more than 70%, there is no crushing and damage to the road surface, the steering resistance is small and the overall vehicle steering energy consumption is lower.

[0029] 4. Simple control logic and high operational reliability: Control is achieved by relying on mature on-board electronic differential technology and electromagnetic braking technology. There is no need for complex attitude calculation algorithms. The VCU program is easy to debug and the electronic control failure rate is low. High and low configuration models can be selected in a modular manner, which can be adapted to various types of models such as passenger entertainment vehicles, light transport vehicles, and field operation vehicles.

[0030] 5. Excellent driving stability: The split-type staggered all-around wheels have multiple ground contact points, combined with the parallel four-link suspension limiter. Under both no-load and heavy-load conditions, the wheels are perpendicular to the ground and in contact with the ground. There is no jamming or rollover deviation when steering. The steering center is controllable and fixed, and the steering smoothness is better than that of traditional simple differential steering vehicles. Attached Figure Description

[0031] Figure 1 This is a schematic diagram of a vehicle structure for efficient on-the-spot steering using a four-wheel hybrid wheel system according to the present invention;

[0032] Figure 2 This is a schematic diagram of a split-type omnidirectional wheel, representing a high-efficiency stationary steering vehicle structure for a four-wheel hybrid wheel system according to the present invention.

[0033] Figure 3 This is a schematic diagram of a high-efficiency stationary steering vehicle structure with two or more points of contact with the ground, based on a four-wheel hybrid wheel system according to the present invention.

[0034] Figure 4 This is a schematic diagram of a seamless circle representing a high-efficiency stationary steering vehicle structure with a four-wheel hybrid wheel system according to the present invention.

[0035] Figure 5 The angle at which the accelerator pedal is depressed is the angle of a highly efficient stationary steering control method for a four-wheel hybrid wheel system according to the present invention.

[0036] Figure 6 This is a schematic diagram of the steering wheel angle for a high-efficiency stationary steering control method for a four-wheel hybrid wheel system according to the present invention.

[0037] Figure 7 This is a schematic diagram of the steering wheel being centered in a highly efficient stationary steering control method for a four-wheel hybrid wheel system according to the present invention.

[0038] Figure 8 This is a schematic diagram of a steering motion control method for a highly efficient stationary steering control method for a four-wheel hybrid wheel system according to the present invention.

[0039] In the diagram: 1. Vehicle body; 2. Split-type all-around wheels; 3. Parallel four-link independent suspension; 4. Rear pneumatic tire; 5. Independent drive motor; 6. VCU vehicle control unit; 7. Roller. Detailed Implementation

[0040] The technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings of the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments.

[0041] In the description of this invention, it should be noted that the terms "upper," "lower," "inner," "outer," "front end," "rear end," "both ends," "one end," and "the other end," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are used only for the convenience of describing this invention and for simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this invention. Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance.

[0042] In the description of this invention, it should be noted that, unless otherwise explicitly specified and limited, the terms "installed," "equipped with," "connected," etc., should be interpreted broadly. For example, "connection" can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium; it can be a connection within two components. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0043] Please see Figure 1-8The present invention provides an embodiment of a high-efficiency stationary steering vehicle structure with a four-wheel hybrid wheel system, which consists of a vehicle body 1, a front wheel system, a rear wheel system, a front suspension system, a dual-motor drive system, and a vehicle control unit (VCU). The vehicle eliminates the entire set of Ackermann steering gears, steering tie rods, steering motors, and other deflection mechanisms, and relies solely on wheel speed difference and lateral slippage of the front wheels to complete steering.

[0044] Two sets of split-type omnidirectional wheels 2 are symmetrically assembled on the front axle, namely the left front split-type omnidirectional wheel 2 and the right front split-type omnidirectional wheel 2; the single set of split-type omnidirectional wheels 2 is composed of two independent wheel bodies coaxially assembled, and the rollers 7 of the two wheel bodies are installed in completely misaligned phases to avoid grounding gaps; each wheel body is uniformly equipped with freely rotating cylindrical rollers 7 on its outer circumference, and the rollers 7 are unpowered and passively slide against the ground.

[0045] Key limiting parameters: The formula for calculating the angle between the axis of roller 7 and the axis of the wheel axle is: θ = 360° ÷ N ÷ 2, where N is the number of rollers 7 on a single wheel body, and the angle θ ranges from 45° to 90°. After assembly, from a perspective perpendicular to the wheel axle axis, the wheel body forms a fully covered, uninterrupted circular grounding structure with ≥2 grounding points per wheel, resulting in good vibration reduction and strong load-bearing stability. The split-type staggered structure can compensate for the dead angles of grounding on a single roller 7, ensuring unobstructed lateral sliding in any direction.

[0046] The rear axle is equipped with two standard pneumatic rubber tires of the same specification, which are the only power drive wheels of the vehicle. They have conventional grip, climbing and braking capabilities and are suitable for all working conditions, including fields, gravel and cement roads.

[0047] It adopts a parallel four-link independent suspension with equal length upper and lower rocker arms 3, which is specially adapted to the working conditions of the split-type all-around wheel 2; when the vehicle is bumpy or the body is tilted, the parallel four-link structure closes the limit, always ensuring that the normal line of the front wheel is perpendicular to the ground, eliminating wheel tilting and jamming, and ensuring that the lateral slip freedom of the all-around wheel is not affected by the suspension bounce.

[0048] The rear-mounted distributed dual hub motor / rear axle independent drive motor 5, with each of the left and right rear wheels driven independently, and the speed and direction of the left and right motors can be independently controlled by the VCU to achieve forward differential and reverse differential speed adjustment, and adapt to multi-level stationary steering.

[0049] It is compatible with low-cost and simplified vehicle models for optional installation, including a single fuel engine / single drive motor, mechanical vehicle differential, and electromagnetic rear wheel brake calipers; a single power source outputs power uniformly, which is distributed to the left and right rear wheels through the differential, and the brake calipers are controlled to lock one side of the rear wheel, so that simple on-the-spot steering can be achieved by relying on differential power distribution, further reducing the overall vehicle cost.

[0050] It has a built-in electronic differential calculation program that is electrically connected to the accelerator pedal sensor, steering wheel angle sensor, left and right rear drive motors, and rear wheel brake assembly. It collects pedal opening and steering wheel angle signals and controls the rear wheel speed, steering, and braking status in real time in a closed loop.

[0051] The four-wheel hybrid system employs a highly efficient stationary steering control method, utilizing a dual-motor precise full-range steering control mode. The control inputs are pedal opening α (0~100%) and steering wheel angle β (-100%~100%, left positive, right negative). The steering coefficient γ is defined as: real-time steering wheel deflection / maximum steering wheel deflection. The straight-line reference speed V is set.

[0052] 1. Straight driving condition: γ=0, steering wheel is returned to zero, VCU controls the speed of the left and right rear wheels V1=V2=V, there is no lateral slippage of the front and rear wheels, and the whole vehicle travels in a straight line at a constant speed;

[0053] 2. Small-angle flexible steering: 0 < γ < 0.5. Taking left turn as an example, the left rear wheel decelerates V1 = V(1-2γ), the right rear wheel maintains the reference speed V2 = V, the front wheel adaptively slips slightly laterally, and the whole vehicle turns left smoothly with a small radius.

[0054] 3. Single rear wheel stationary turning: γ=0.5. Taking left turn as an example, the left rear wheel locks at a speed of V1=0, the right rear wheel maintains V2=V, and the whole vehicle turns left in place around the center point of the left rear wheel's ground contact.

[0055] 4. Eccentric turning in place within the wheel track range: 0.5 < γ < 1. Taking left turn as an example, the left rear wheel reverses direction by V1 = -V(2γ-1), while the right rear wheel maintains V2 = V. The entire vehicle eccentrically turns left in place around any point between the left and right rear wheels.

[0056] 5. Vehicle's geometric center rotates in place: γ=1, the steering wheel turns fully to the left, the left rear wheel moves in the opposite direction at the same speed V1=-V, the right rear wheel moves in the forward direction V2=V, and the vehicle precisely rotates 360° around the geometric center of the rear wheel to make a turn.

[0057] It will be apparent to those skilled in the art that the present invention is not limited to the details of the exemplary embodiments described above, and that the invention can be implemented in other specific forms without departing from its spirit or essential characteristics. Therefore, the embodiments should be considered in all respects as exemplary and non-limiting, and the scope of the invention is defined by the appended claims rather than the foregoing description. Thus, all variations falling within the meaning and scope of equivalents of the claims are intended to be included within the present invention. No reference numerals in the claims should be construed as limiting the scope of the claims.

Claims

1. A highly efficient vehicle structure for stationary steering with a four-wheel hybrid wheel system, characterized in that, Includes the vehicle body (1), front wheel system, rear wheel system, front suspension system, drive system and vehicle control unit (VCU); The front wheel system and the rear wheel system are respectively installed on the front axle and the rear axle of the vehicle body (1). The front suspension system connects the vehicle body (1) and the front wheel system. The drive system is installed on the rear axle and drives the rear wheel system to operate. The vehicle control unit (VCU) is electrically connected to the drive system. The front wheel system includes a symmetrically arranged left front split-type omnidirectional wheel (2) and a right front split-type omnidirectional wheel (2). Each split-type omnidirectional wheel (2) consists of two independent wheel bodies that are coaxially mounted and have rollers (7) with phase misalignment. Each wheel body has freely rotating rollers (7) evenly arranged around its circumference. The angle between the axis of the roller (7) and the axis of the wheel axle satisfies the formula: Angle = 360° ÷ Number of rollers (7) per wheel ÷ 2. After the two wheel bodies are assembled, a seamless circular grounding structure is formed perpendicular to the wheel axle direction. The rear wheel system includes a symmetrically arranged left rear pneumatic tire (4) and a right rear pneumatic tire (4). Both the left rear pneumatic tire (4) and the right rear pneumatic tire (4) are standard automotive rubber pneumatic tires. The front suspension system adopts a parallel four-link independent suspension (3) with equal upper and lower rocker arms, which is used to constrain the split all-wheel (2) to always be perpendicular to the vehicle body (1) when it bounces. The drive system is a dual-motor independent drive structure, including a left rear drive motor and a right rear drive motor. The left rear drive motor and the right rear drive motor drive the left rear pneumatic tire (4) and the right rear pneumatic tire (4) respectively. The Ackermann steering mechanism is eliminated in the whole vehicle, and the vehicle steering is achieved by relying on the lateral slip of the front wheel and the speed difference of the rear wheel.

2. The efficient on-the-spot steering vehicle structure of a four-wheel hybrid wheel system according to claim 1, characterized in that, The angle between the axis of the roller (7) of the single-component omnidirectional wheel (2) and the axis of the wheel axle is 45°~90°. The two independent wheel rollers (7) are installed with staggered phase angles to ensure that there are no less than two grounding points.

3. A highly efficient on-the-spot steering control method for a four-wheel hybrid wheel system, applied to a four-wheel hybrid wheel system vehicle as described in any one of claims 1-2, characterized in that, The vehicle control unit (VCU) collects accelerator pedal opening α and steering wheel angle β to achieve graded steering control. The accelerator pedal opening α ranges from 0 to 100%. Left steering wheel turn is defined as a positive angle and right steering wheel turn as a negative angle. A steering coefficient γ is set, where γ = current steering wheel deflection / maximum steering wheel deflection. The baseline straight-line vehicle speed is V. The specific control steps are as follows: S1, Straight Driving Condition: The steering wheel is centered with no deflection, γ=0, the vehicle control unit (VCU) controls the speed of the left rear drive motor V1 and the speed of the right rear drive motor V2 to satisfy V1=V2=V, and the whole vehicle travels straight at a constant speed. S2, Small-angle differential steering condition: The steering wheel is turned to one side, and 0 < γ < 0.

5. Taking left turn as an example, the vehicle control unit (VCU) regulates the speed of the left rear drive motor V1 = V(1-2γ), while the right rear drive motor keeps the speed V2 = V constant. The small-radius left turn is achieved by relying on the lateral slip of the front wheels. S3, Single rear wheel fixed-point steering condition: The steering wheel is turned to one side and γ=0.

5. Taking left turn as an example, the vehicle control unit VCU adjusts the speed of the left rear drive motor V1=0, and the speed of the right rear drive motor V2=V remains unchanged. The whole vehicle turns left around the contact point of the left rear pneumatic tire (4). S4, Fixed-point turning condition within the wheel track range: The steering wheel is turned to one side, and 0.5 < γ < 1. Taking left turn as an example, the vehicle control unit (VCU) adjusts the reverse speed of the left rear drive motor to V1 = -V(2γ-1), while the right rear drive motor keeps the speed V2 = V constant. The whole vehicle turns left in place around the inner interval of the left and right rear wheel track. S5, Vehicle geometric center stationary turning condition: The steering wheel is turned to the maximum opening, γ=1. Taking left turn as an example, the vehicle control unit (VCU) adjusts the left rear drive motor to reverse speed V1=-V, while the right rear drive motor keeps the speed V2=V unchanged. The vehicle completes stationary center turning around the geometric center of the rear wheel track.

4. The efficient on-the-spot steering control method for a four-wheel hybrid wheel system according to claim 4, characterized in that, During vehicle steering, the parallel four-link independent suspension (3) constrains the verticality of the split all-around wheel (2) in real time, offsetting the wheel body deflection caused by the pitch and roll of the vehicle body (1), and ensuring that the roller (7) slides freely in contact with the ground.

Images