Dual-motor rotating speed cooperative control method for drifting vehicle

Abstract

The invention discloses a dual-motor rotating speed cooperative control method and device for a drifting vehicle. A left front wheel and a right front wheel of the drifting vehicle are respectively driven by two independent motors, and a rear wheel is a universal wheel. The core of the method is that a special user drift control instruction signal is introduced to cooperate with a vehicle steering state and a user driving power instruction so as to determine a target rotating speed difference control strategy. The control strategy is embodied by a target rotational speed difference direction coefficient (K), and the K value continuously varies according to the drift control command signal. When the vehicle steers, a normal driving mode, a drifting sideslip mode, a drifting fixed circle mode and seamless and linear switching among multiple driving modes are easily achieved by enabling the K value to be in continuous transition among positive, zero and negative. According to the method, a driver can intuitively and continuously adjust the yawing moment of the vehicle through a single control dimension, and the fun and controllability of drifting control are greatly improved.

Description

Technical Field

[0001] This invention relates to the field of vehicle control technology, specifically to a drift car with a special drive structure and its dual-motor speed coordinated control method. Background Technology

[0002] Existing remote-controlled cars, toy cars, or small electric vehicles typically rely on a mechanical steering mechanism on the front wheels for steering, while the drive system usually involves a single motor driving the two rear wheels or the front wheels via a differential. When turning, the differential automatically adjusts the speed of the inner and outer wheels to achieve smooth Ackerman steering. However, this traditional structure cannot achieve active, controllable drifting maneuvers.

[0003] Some high-end models or experimental vehicles employ a dual-motor layout that independently drives either the front or rear wheels. However, their control strategies are mostly focused on improving tracking performance or achieving tank turning (U-turns), lacking a dedicated control method that allows users to seamlessly and continuously switch between various driving modes such as normal steering, stable sideslip, and aggressive circular maneuvering. Especially in front-wheel drive configurations with free-swivel rear wheels, there is currently no mature solution in the technology for continuously controlling the vehicle's yaw moment through an intuitive user command (such as a single pedal).

[0004] Furthermore, as disclosed in Chinese utility model patent CN213292546U, a drift car, while also employing a structure with dual independent front-wheel motors and a swing-out rear wheel, reveals the core limitations of existing technology in its drive control method. This scheme uses three independent pedals (left, center, and right) to send three discrete, fixed-mode commands: "left turn differential," "same speed forward," and "right turn differential," respectively. Its design aims to generate a traditional "Ackermann" differential by controlling the motors to make the outer wheels rotate faster than the inner wheels during steering, thus assisting in smooth steering and preventing rollover. This control method is essentially a passive differential logic serving "stable driving." The driver can only switch between preset discrete states by selecting different pedals, completely unable to continuously, linearly, and steplessly adjust the yaw torque used to actively control the vehicle's yaw attitude. Therefore, this scheme is difficult to achieve a smooth transition from normal driving to active drifting (especially aggressive fixed-circle drifting), and it cannot allow the driver to intuitively and continuously control the drifting process. The intuitiveness, fun and controllability of the operation are all inherently lacking. Summary of the Invention

[0005] The purpose of this invention is to overcome the shortcomings of the prior art and provide a drift car and its dual-motor speed coordinated control method. This method can achieve precise, continuous and seamless control of the vehicle in various driving modes such as normal driving, drifting and side-slipping and drifting in a fixed circle when the vehicle is moving forward, through a dedicated and continuously adjustable user command.

[0006] To achieve the above objectives, the present invention adopts the following technical solution: In a first aspect, the present invention provides a dual-motor speed coordination control method for a drift car, the drift car having a frame, a front wheel steering assembly mounted on the frame, a left front wheel and a right front wheel that are mechanically driven independently by two independent motors, and at least one omnidirectional rear wheel that does not have active steering function. The left front wheel and the right front wheel are mechanically independent at the driving level, that is, there is no mechanical differential or shared drive shaft between them, and each wheel is driven by a corresponding independent motor through a dedicated transmission path.

[0007] The method includes the following steps: Signal acquisition steps: Real-time acquisition of vehicle steering status signals, user drive power command signals, and user drift control command signals; Control decision-making steps: Based on the user drift control command signal, determine the target speed difference control strategy; Speed ​​synthesis step: Based on the vehicle steering state signal, the user drive power command signal, and the target speed difference control strategy, synthesize the target speeds of the left front wheel and the right front wheel respectively, wherein the target speed difference control strategy is used to coordinate with the vehicle steering state signal to define the direction and magnitude relationship of the difference between the target speeds of the left front wheel and the right front wheel; Drive execution steps: Control the two independent motors to run at their respective target speeds.

[0008] Preferably, the user drift control command signal is a continuously variable signal; the control decision step includes: continuously adjusting the target speed difference control strategy according to the real-time value of the user drift control command signal.

[0009] Furthermore, the target speed difference control strategy is embodied by a target speed difference direction coefficient; when the vehicle steering state signal indicates steering, the sign of the target speed difference direction coefficient is coordinated with the vehicle steering state signal to determine the direction of the target speed difference, and its absolute value is used to affect the magnitude of the target speed difference.

[0010] Furthermore, the user drift control command signal comes from the opening signal of a dedicated drift control pedal; the value of the target speed difference direction coefficient is configured to change continuously with the change of the opening signal, and within the first change range of the opening signal, the absolute value of the coefficient decreases as the opening increases; within the second change range of the opening signal, the sign of the coefficient is opposite to that of the first change range, and its absolute value increases as the opening increases.

[0011] Furthermore, within the first variation range of the opening signal, corresponding to the normal driving mode, the target speed difference direction coefficient is configured such that when the vehicle steering state signal indicates steering, the target speed of the outer front wheel is higher than that of the inner front wheel. Within the second variation range of the opening signal, corresponding to the drifting circle mode, the target speed difference direction coefficient is configured such that when the vehicle steering state signal indicates steering, the target speed of the inner front wheel is higher than that of the outer front wheel.

[0012] Furthermore, the intermediate value of the opening signal corresponds to the drift and sideslip mode; wherein, the intermediate value is an intermediate value point or a narrow interval between the first and second variation intervals within the entire variation range of the opening signal; when the opening signal is within this value point or the narrow interval, the target speed difference direction coefficient is configured to maintain the target speed difference between the left front wheel and the right front wheel within a range where the absolute value is less than or equal to a preset threshold.

[0013] As another optional implementation, the user drift control command signal is a multi-gear discrete signal, including at least a first gear corresponding to the normal driving mode, a second gear corresponding to the drift sideslip mode, and a third gear corresponding to the drift circle mode.

[0014] In this discrete control method, preferably: in the first gear, when the vehicle steering status signal indicates steering, the target speed difference control strategy is configured to make the target speed of the outer front wheel higher than that of the inner front wheel; in the second gear, when the vehicle steering status signal indicates steering, the target speed difference control strategy is configured to maintain the target speed difference between the left and right front wheels within a range where the absolute value is less than or equal to a preset threshold; in the third gear, when the vehicle steering status signal indicates steering, the target speed difference control strategy is configured to make the target speed of the inner front wheel higher than that of the outer front wheel.

[0015] In addition, the user drive power command signal comes from the accelerator pedal, speed knob, or handle trigger.

[0016] Secondly, the present invention also provides a drift car implementing any of the above-mentioned control methods. The drift car includes: a frame; a front wheel steering assembly mounted on the frame; a left front wheel and a right front wheel steerably mounted on the frame and mechanically driven independently by two independent motors; at least one rear wheel mounted on the rear of the frame, which is a swivel wheel without active steering function; a vehicle status sensing module for acquiring vehicle steering status signals; a user command input module for acquiring user drive power command signals and user drift control command signals; and a control mechanism including a processor, a memory, and a motor driver for driving the two independent motors. The memory stores a computer program, and the processor is configured to execute the computer program to generate control commands and control the operation of the two independent motors through the motor driver. The control mechanism is signal-connected to the vehicle status sensing module and the user command input module, and is configured to execute the dual-motor speed cooperative control method as described above based on signals from the vehicle status sensing module and the user command input module to control the two independent motors. Beneficial effects

[0017] Compared with the prior art, the drift car and its control method provided by the present invention have the following advantages: 1. By creatively introducing an independent user drift control command signal and coordinating it with the vehicle steering status signal, the driver can actively and linearly controllably adjust the vehicle's yaw moment through a single operation dimension, thereby achieving seamless and precise switching between various driving modes such as normal driving, stable sideslip, and aggressive circular driving.

[0018] 2. By configuring the drift control command as a continuously variable signal and mapping it to a continuously changing target speed difference direction coefficient, a full-spectrum, continuous transition is achieved between normal steering based on the "Ackermann" differential and constant-circle drift characterized by the "anti-Ackermann" differential. This design makes the switching of driving modes intuitive, predictable, and fun to drive.

[0019] 3. The control method described herein is specifically tailored for a particular mechanical architecture with dual independent front-wheel motors and omnidirectional wheels at the rear. This architecture completely eliminates the constraints of traditional mechanical differentials, providing a physical basis for the cooperative control strategy, highly simplifying the control logic, achieving high execution efficiency, and facilitating engineering implementation. Attached Figure Description

[0020] Figure 1 This is a top view schematic diagram of the overall vehicle structure of an embodiment of the drift car of the present invention.

[0021] Figure 2 This is a block diagram of one embodiment of the control system of the present invention.

[0022] Figure 3 This is a flowchart of one embodiment of the control method of the present invention.

[0023] Figure 4 This is a mapping diagram of one embodiment of the relationship between the "target speed difference direction coefficient" and the "drift control pedal opening".

[0024] Figure 5 This is a three-dimensional schematic diagram of the overall structure of a drift car according to an embodiment of the present invention.

[0025] In the diagram: 1. Chassis, 2. Front wheel steering assembly, 3. Left front wheel, 4. Right front wheel, 5. Left independent motor, 6. Right independent motor, 7. Rear wheel, 8. Front wheel steering angle sensor, 9. Accelerator pedal, 10. Drift control pedal, 11. Microcontroller, 12. Left motor driver, 13. Right motor driver. Detailed Implementation

[0026] The present invention will now be described in detail with reference to the accompanying drawings and embodiments. It should be understood that the following description is intended to explain the present invention, rather than to limit its scope of protection.

[0027] To make the technical solution of this invention clearer, the key signals and vehicle states that will be frequently used throughout this invention will first be described and defined. The following descriptions and definitions are intended to clarify the technical solution of this invention, and in particular to explain the relevant terms in the appended claims. It should be understood that these definitions are a clear and consistent way of expressing the specific control logic of this invention.

[0028] 1. Vehicle turning status signal: The "vehicle steering status signal" refers to an electrical signal that can directly or indirectly reflect the desired or actual steering direction and degree of the vehicle. It can be, but is not limited to: a directly measured front wheel steering angle signal; a signal output by a steering wheel angle sensor (which can be correlated to the front wheel angle through a fixed gear ratio); or an equivalent steering intention signal derived from information from other sensors (such as a vision system). This signal typically contains directional information (such as left or right turn) and amplitude information (such as the size of the steering angle).

[0029] 2. User-driven power command signal: The "user drive power command signal" refers to an electrical signal generated by user operation that instructs the output power (expressed as torque or speed) of the vehicle drive system. Its source can be, but is not limited to, input devices directly operated by the user to control the vehicle's forward power, such as linear throttle pedals, speed setting knobs, lever triggers, or cruise control modules.

[0030] 3. User drift control command signal: The "user drift control command signal" refers to a dedicated electrical signal actively issued by the user to instruct the vehicle to enter a specific driving mode or adjust the degree of yaw moment control. As described in the claim, it can be a continuously variable signal from a dedicated pedal or a multi-position discrete signal from a button or switch.

[0031] 4. Definition of steering direction and inner / outer wheel: In the control logic of this invention, based on the actual physical structure of the vehicle, the value of the vehicle steering state signal is fixed as follows: Directional convention: When the physical state corresponding to the signal is that the front wheels are turning to the left or the driver issues a left turn command, the value of the signal is defined as positive; conversely, when the physical state is that the front wheels are turning to the right or the driver issues a right turn command, the value of the signal is defined as negative.

[0032] Amplitude convention: It is also stipulated that the absolute value of the signal is positively correlated with the amplitude of the deflection or command.

[0033] Based on the above conventions regarding sign and amplitude, and by setting a non-negative dead zone threshold δ (δ≥0), the vehicle steering direction is determined by the real-time acquired signal values ​​as follows: When the signal value is greater than δ, it is determined that the vehicle is turning left; When the signal value is less than -δ, it is determined that the vehicle is turning right; When the absolute value of the signal is less than or equal to δ (i.e., within the interval [-δ, +δ]), the vehicle is determined to be going straight.

[0034] Based on the above definition of steering direction, the inner and outer sides of the front wheels are defined during steering: When the turn is defined as a left turn, the right front wheel is the outer front wheel and the left front wheel is the inner front wheel; When the turn is defined as a right turn, the left front wheel is the outer front wheel and the right front wheel is the inner front wheel; When traveling straight, there is no distinction between inside and outside.

[0035] It should be noted that the present invention adopts the above-mentioned definition method based on electrical signal values, aiming to provide a clear, stable, and real-time logical judgment benchmark for the coordinated control of dual motor speeds. The "vehicle steering state signal" directly originates from sensors reflecting the driver's steering intention or the actual yaw angle of the front wheels (such as steering wheel angle sensor, front wheel steering angle sensor), and its magnitude and direction represent the commanded or executed steering input. In situations where the vehicle body posture and wheel direction may be significantly separated, such as during drifting, the core of the present invention lies in "commanding" the desired drift posture through the driver's front wheel steering input, rather than "following" the vehicle body state. Therefore, the "steering" is deliberately defined without relying on complex state feedback signals such as the vehicle body yaw rate, but rather based on this feedforward or directly measured signal. This approach avoids control benchmark inaccuracies and system oscillations caused by severe vehicle body sideslip, ensuring the simplicity, robustness, and real-time response of the control logic, which is one of the key design features of the present invention that enables stable and continuous drift control.

[0036] 5. Explanation of the core inventive step of this invention: Based on the above definitions and logic, it is necessary to further clarify the core inventiveness of this invention. While existing technologies (such as CN213292546U cited in the background section) also employ independent dual-motor drive, their control commands are discrete and their modes are fixed. Specifically, they use three independent pedals (left, center, and right) with three fixed states. The fundamental purpose of this design is to prevent vehicle rollover and maintain driving stability during steering through differential assistance. Its differential logic is to make the outer wheel rotate at a higher speed than the inner wheel, falling under the traditional "Ackerman steering" category. It lacks the ability to continuously, linearly, and steplessly control the vehicle's yaw moment, preventing users from smoothly transitioning between normal driving and aggressive drifting, and making it impossible to actively induce and maintain a stable drift posture.

[0037] The fundamental difference and creative contribution of this invention compared to existing technologies lies in the innovative introduction of an independent, continuously adjustable "user drift control command signal," which is then coordinated with the "vehicle steering state signal" to serve as a decision input, continuously defining or determining the direction and magnitude of the difference in target rotational speeds between the left and right drive wheels. This allows a single command dimension to map a continuous spectrum of vehicle dynamic response, rather than several discrete fixed states.

[0038] This ingenious combination achieves revolutionary manipulation effects, and its three typical modes are fundamentally different from existing technologies: Normal Driving Mode: When the user's drift control command signal is on one side, the system generates a differential that makes the outer front wheel rotate at a higher speed, achieving smooth steering. Although this mode is physically similar to the existing "left / right turn differential" mode, it is not achieved by selecting discrete gears, but by continuously adjusting a range of states during the process.

[0039] Drift Sideslip Mode: When the user's drift control command signal is at the middle value, the system makes the target speeds of the left and right front wheels basically the same (the difference is approximately zero). This state is a brand-new driving mode that the existing "same speed forward" mode does not have. It is specifically designed to actively achieve and maintain the vehicle's stable sideslip posture, rather than simply going straight.

[0040] Drifting in a fixed circle mode: When the user's drift control command signal is on the other side, the system generates a differential that makes the inner front wheel rotate at a higher speed. This creates a crucial "anti-Ackermann" differential effect, actively generating a yaw moment that causes the rear of the car to swing inward into the corner, which is the core of achieving aggressive fixed-circle drifting. This is physically the complete opposite of the logic of existing technologies that design the outer wheel to be faster for the sake of "stability," and their purposes are completely different.

[0041] Crucially, by continuously adjusting the command signals between the aforementioned states, the driver can achieve a seamless, continuous, and linearly controllable transition from normal cornering to stable sideslip and then to circular drift.

[0042] Therefore, the core inventiveness of this invention lies not in achieving differential speed itself, but in pioneering an intuitive single continuous control dimension that integrates the entire dynamic spectrum of the vehicle from "stable steering" to "active drifting" under a coherent, steplessly adjustable control logic, thereby giving the driver an unprecedented ability to linearly, precisely, and actively control the vehicle's drifting posture.

[0043] The following examples mainly describe the control method for a vehicle in a forward driving state. Example 1:

[0044] See Figure 1 , Figure 5 This invention demonstrates the mechanical structure of a drift car. The frame 1 forms the main body. A front wheel steering assembly 2 (e.g., a steering linkage mechanism driven by a steering wheel) is mounted at the front of the frame 1 and controls the steering angles of the left front wheel 3 and the right front wheel 4. Crucially, the left front wheel 3 and the right front wheel 4 are completely independent in their driving. The left front wheel 3 is driven by a left independent motor 5; the right front wheel 4 is driven by a right independent motor 6. There is no mechanical connection between the two drive systems (e.g., no shared axle or differential). The rear wheels 7 are one or more omnidirectional wheels, providing only support and follow-up functions, without driving or active steering capabilities.

[0045] See Figure 2The control system architecture of the present invention is illustrated. The vehicle state sensing module includes a front wheel steering angle sensor 8 (such as a potentiometer mounted on the steering shaft) for measuring and outputting the vehicle steering state signal (i.e., the front wheel steering angle θ). The user command input module includes two parts: an accelerator pedal 9 for outputting a user drive power command signal (T); and a dedicated drift control pedal 10 for outputting a user drift control command signal (P). The drift control pedal 10 is preferably a linear sensor that can output a continuously varying opening signal (e.g., 0%-100%).

[0046] In this embodiment, the user drift control command signal is a continuously variable signal, namely, the opening signal from the dedicated drift control pedal 10. In this continuous control mode, the control strategy is embodied by a "target speed difference direction coefficient" (i.e., coefficient K). The sign of coefficient K is coordinated with the vehicle steering state signal to determine the direction of the target speed difference, and its absolute value influences the magnitude of the target speed difference. Coefficient K is configured to continuously change with the pedal opening P: when the opening P increases from its minimum value to its intermediate value, coefficient K starts from a positive range and monotonically decreases towards zero; when the opening P increases from its intermediate value to its maximum value, coefficient K starts from zero and monotonically decreases towards the negative direction until it reaches a negative range.

[0047] The control mechanism includes a microcontroller 11, a left motor driver 12, and a right motor driver 13. The microcontroller 11 internally contains a processor and a memory, which stores a computer program implementing the control method of this invention. The microcontroller 11 receives signals from the front wheel steering angle sensor 8, a user drive power command signal T from the accelerator pedal 9, and a user drift control command signal P from the drift control pedal 10 via its analog-to-digital converter (ADC) interface. After performing calculations according to the program, the microcontroller 11 outputs two control signals via its pulse width modulation (PWM) interface, which are sent to the left motor driver 12 and the right motor driver 13 respectively, ultimately driving the left independent motor 5 and the right independent motor 6.

[0048] In summary, the front wheel steering angle sensor 8 constitutes the vehicle status sensing module; the accelerator pedal 9 and drift control pedal 10 together constitute the user command input module; and the microcontroller 11, memory, left motor driver 12, and right motor driver 13 constitute the control mechanism.

[0049] See Figure 3 The main flow of the control method of the present invention is shown.

[0050] Step S101: Real-time acquisition of all input signals: front wheel steering angle θ, throttle command T, drift control pedal opening P.

[0051] Step S102: Based on the drift control pedal opening P, query or calculate the current target speed difference direction coefficient K. The mapping relationship between K and P is shown below. Figure 4 .

[0052] Step S103: Calculate the base target speed N_base based on the throttle command T. For example, N_base can be proportional to T.

[0053] Step S104: Calculate the steering correction. Based on the front wheel steering angle θ, calculate the steering correction ΔN. The steering correction ΔN is configured to be associated with the front wheel steering angle θ, its value is positively correlated with |θ|, and its sign is the same as that of θ. For example, in a specific calculation embodiment, the steering correction ΔN can be calculated by the following formula: ΔN = C · θ, where C is a positive constant coefficient. This relationship ensures that the sign of the steering correction ΔN is the same as that of the steering angle θ, and its absolute value is positively correlated with the absolute value of the steering angle θ. The steering correction ΔN is used to convert the steering angle into a reference quantity for speed adjustment. Its specific functional relationship (such as linear, piecewise linear, or nonlinear) can be adjusted according to the vehicle dynamics characteristics, but it must be ensured that its sign is consistent with the steering direction, and its absolute value increases with the increase of the steering angle.

[0054] Step S105: Speed ​​Synthesis. Based on the base target speed N_base, steering correction ΔN, and target speed difference direction coefficient K, synthesize the target speeds N_left and N_right for the left and right front wheels respectively.

[0055] The synthesis logic is configured such that the direction and magnitude of the target speed difference (N_left - N_right) between the left and right front wheels are jointly controlled by the coefficient K and the steering correction ΔN. As a preferred implementation, the above logic can be achieved by making the target speed difference (N_left - N_right) proportional to (-2 · K · ΔN).

[0056] For example, in a preferred symmetric control embodiment, the above synthesis logic can be implemented using the following formula: Target rotational speed of the left front wheel N_left = N_base - K · ΔN Target rotational speed of the right front wheel: N_right = N_base + K · ΔN The following section, using specific steering directions as an example, explains how the above formula achieves different driving modes: According to the definition in step S104, the sign of the steering correction amount ΔN is the same as that of the steering angle θ. Combining the previous definition of the "outer front wheel" and the configuration of the coefficient K, the above formula ensures that the desired differential effect is produced in all modes: Normal driving mode (K > 0): When the vehicle turns left (ΔN > 0): It is calculated that N_left = N_base - K · ΔN, N_right = N_base + K · ΔN. Since K > 0 and ΔN > 0, then K · ΔN > 0, and it can be deduced that N_left < N_right. At this time, the target rotational speed of the right front wheel (outer front wheel) is higher than that of the left front wheel (inner front wheel), meeting the differential requirements for normal steering.

[0057] When the vehicle turns right (ΔN < 0): It is calculated that N_left = N_base - K · ΔN, N_right = N_base + K · ΔN. Since K > 0 and ΔN < 0, then K · ΔN < 0, and it can be deduced that N_left > N_right. At this time, the target rotational speed of the left front wheel (outer front wheel) is higher than that of the right front wheel (inner front wheel), meeting the differential requirements for normal steering.

[0058] Drift circle mode (K < 0): When the vehicle turns left (ΔN > 0): It is calculated that N_left = N_base - K · ΔN, N_right = N_base + K · ΔN. Since K < 0 and ΔN > 0, then K · ΔN < 0, and it can be deduced that N_left > N_right. At this time, the target rotational speed of the left front wheel (inner front wheel) is higher than that of the right front wheel (outer front wheel), thus generating a yaw moment that causes the rear of the vehicle to "tighten" towards the inside (left side).

[0059] When the vehicle turns right (ΔN < 0): It is calculated that N_left = N_base - K · ΔN, N_right = N_base + K · ΔN. Since K < 0 and ΔN < 0, then K · ΔN > 0, and it can be deduced that N_left < N_right. At this time, the target rotational speed of the right front wheel (inner front wheel) is higher than that of the left front wheel (outer front wheel), thus generating a yaw moment that causes the rear of the vehicle to "tighten" towards the inside (right side).

[0060] In summary, in the drift circle mode, by making the target speed of the inner front wheel higher than that of the outer front wheel, a key "anti-Ackermann" differential effect is generated. This differential relationship is the core of achieving and maintaining aggressive circle drift, and is fundamentally different from the ordinary differential logic in existing technologies (such as CN213292546U) where the outer wheel speed is higher only to assist in smooth steering.

[0061] Drift and sideslip mode (K ≈ 0): At this point, K · ΔN ≈ 0, therefore N_left ≈ N_base ≈ N_right, the difference in speed between the left and right wheels is minimal, which is beneficial for maintaining stable sideslip.

[0062] It is understood that the above mathematical expression is merely a preferred example for implementing the synthetic logic. Any method for synthesizing rotational speeds that achieves the same control objective—namely, when the vehicle is turning (ΔN ≠ 0), the target rotational speed relationship between the outer and inner front wheels is determined by the sign of the coefficient K, and the magnitude of the speed difference is related to |K| and |ΔN|—falls within the scope of this invention.

[0063] Post-processing and engineering implementation of target rotational speed: The target rotational speeds (N_left, N_right) of the left and right front wheels calculated in step S105 above are theoretical values ​​derived from the core control logic. In actual vehicle control systems, to ensure the safety, executability, and smoothness of control commands, a series of post-processing steps are usually performed before sending the target rotational speeds to the motor driver.

[0064] Such post-processing is a conventional technique in control engineering and may include, but is not limited to: Limiting: The target speed is limited to the allowable operating range of the two independent motors (e.g., the lower limit is 0, and the upper limit is the maximum safe speed N_max). If the calculated value is lower than the lower limit, the lower limit value is used; if it is higher than the upper limit, the upper limit value is used.

[0065] Smoothing: To avoid excessively drastic vehicle dynamic response caused by sudden changes in target speed, methods such as low-pass filtering, ramp functions, or conditional constraints can be used to smooth the rate of change or absolute value of the target speed. For example, in one specific embodiment, when the calculated speed adjustment (K · ΔN) is too large relative to the base speed (N_base), additional constraint rules can be applied to the target speed (such as limiting the ratio or difference between N_left and N_right) to achieve a gentler transition effect.

[0066] Dead zone handling: When the target speed is extremely low, it can be set to zero to avoid the two independent motors operating in an extremely low efficiency range or causing vibration.

[0067] It should be noted that the purpose of all such post-processing steps is to optimize the engineering performance of the system. Their scope is limited to the subsequent processing of the target speed values ​​(N_left, N_right) calculated based on the core control logic, and does not involve or change the control logic itself on which the aforementioned "speed synthesis step" is based.

[0068] Step S106: Convert the calculated N_left and N_right into PWM duty cycles and output them to the left and right motor drivers respectively to control the two independent motors to reach the target speed.

[0069] See Figure 4 It details a preferred, exemplary continuous mapping relationship (such as a linear function) between the coefficient K and the pedal opening P. The horizontal axis represents the drift control pedal opening P (0% to 100%), and the vertical axis represents the target speed difference direction coefficient K.

[0070] When P is in the first variation range (e.g., 0% to 50%), as P increases, K monotonically decreases from a positive value K_max (e.g., +1.0) to zero. Within this range, K > 0. According to the speed synthesis formula, the outer front wheel speed is higher than the inner front wheel during steering, and the vehicle exhibits normal steering characteristics. As P increases and K decreases, the differential effect weakens. This range corresponds to the "normal driving mode" described in the claims.

[0071] When P is in the second variation range (e.g., 50% to 100%), as P increases, K continues to decrease monotonically from zero to a negative value K_min (e.g., -1), and its absolute value gradually increases accordingly. Within this range, K < 0. According to the speed composition formula, during steering, the inner front wheel speed is higher than the outer front wheel speed, generating a yaw moment that causes the rear of the vehicle to "tighten" towards the side where the inner front wheel is located, thus facilitating drifting in a fixed circle. The larger P is, the larger |K| is, and the stronger the fixed circle effect. This range corresponds to the "drifting fixed circle mode" described in the claims.

[0072] When P is at an intermediate value (e.g., 50%) or within a narrow range around that intermediate value (e.g., 48%-52%), the system determines that it has entered a drift sideslip mode. At this time, the target speed difference directional coefficient K is controlled within a range where its absolute value is less than or equal to a preset threshold (e.g., |K| ≤ 0.1), i.e., achieving a state where K≈0. This makes the target speeds of the left and right front wheels essentially the same (N_left ≈ N_right), making it easier for the vehicle to maintain a stable sideslip posture. This is the implementation method of "maintaining the target speed difference within a range where its absolute value is less than or equal to a preset threshold" as described in claim 6.

[0073] The 'intermediate value' or 'narrow range' described in this invention refers to defining a state separation point or transition region experienced by the drift control command signal during continuous change. Physically, this region corresponds to a specific travel position of the user's operating device (such as a pedal), and electrically, it corresponds to a specific numerical range of the output signal. (Appendix) Figure 4 The example shown centered at 50% is merely a preferred and exemplary implementation. Those skilled in the art will understand that, depending on different operating device travel designs, signal calibration methods, or user preferences, the 'drift sideslip mode' can be configured at other appropriate locations within the signal range, as long as it logically lies at the switching boundary between the 'normal driving' and 'drift circle' strategies. This principle of dividing control modes based on the relative position of signals falls within the protection scope of this invention.

[0074] The mapping relationship between the target speed difference direction coefficient K and the user drift control command signal (such as pedal opening P) can be a linear function, a nonlinear function, or a lookup table method, as long as the condition that the value of K changes continuously with the command signal and the sign reverses within a specific interval is met. Figure 4 The example shown is only a preferred linear mapping. Example 2:

[0075] This embodiment provides a control implementation method based on multi-position discrete signals. The user drift control command signal comes from a physical switch with multiple positions (such as a three-position lever or button group, not shown), and its output is a discrete multi-position signal. This signal includes at least three positions: first position, second position, and third position.

[0076] When the user selects the first gear, the system enters normal driving mode. In this mode, the system uses a preset positive value as the target speed difference direction coefficient K (e.g., K = +1.0). According to the speed synthesis formula, when the vehicle is turning, the outer front wheel will rotate at a higher speed than the inner front wheel.

[0077] When the user selects the second gear, the system enters drift and sideslip mode. In this mode, the system sets the target speed difference directional coefficient K to zero or a very small absolute value (e.g., K=0 or |K|≤0.05). At this time, the target speeds of the left and right front wheels are basically the same, making it easier for the vehicle to maintain stable sideslip.

[0078] When the user selects the third gear, the system enters the drift circle mode. In this mode, the system uses a preset negative value as the target speed difference direction coefficient K (e.g., K=-1.0). According to the speed synthesis formula, when the vehicle turns, the inner front wheel speed will be higher than the outer front wheel, generating a yaw moment that causes the rear of the car to "tighten" in the curve.

[0079] In this embodiment, gear shifting directly adjusts the target speed difference control strategy by changing the preset value of the target speed difference direction coefficient K, providing users with a clear and fast way to switch driving modes.

[0080] It should be noted that the method for achieving speed difference control through the target speed difference direction coefficient (K) described above is a preferred and exemplary specific implementation of the present invention. Those skilled in the art will understand that the technical means for achieving control objectives such as "making the target speed of the outer front wheel higher than that of the inner front wheel," "making the target speed of the inner front wheel higher than that of the outer front wheel," or "maintaining the target speed difference within a threshold range" are not limited to the specific mathematical operations described above. Any control strategy that collaboratively generates a corresponding target speed difference relationship based on the user drift control command signal and the vehicle steering state signal (e.g., through different function mappings, lookup tables, or model-based control algorithms), as long as its final execution effect is to make the vehicle exhibit the aforementioned positive differential speed, reverse differential speed, or near-zero differential speed state, falls within the control logic concept protected by the present invention.

[0081] The above embodiments are only used to clearly illustrate the technical solution of the present invention, and are not intended to limit it. Those skilled in the art, within the scope of protection defined by the claims, can make various modifications and changes to the specific curve shape, parameter values, signal processing details, etc., of the mapping relationship. All such modifications and changes fall within the protection scope of the present invention.

Claims

1. A dual-motor speed coordinated control method for a drift car, the drift car having a frame, a front wheel steering assembly mounted on the frame, a left front wheel and a right front wheel respectively driven mechanically by two independent motors, and at least one omnidirectional rear wheel without active steering function, characterized in that, The method includes the following steps: Signal acquisition steps: Real-time acquisition of vehicle steering status signals, user drive power command signals, and user drift control command signals; Control decision-making steps: Based on the user drift control command signal, determine the target speed difference control strategy; Speed ​​synthesis step: Based on the vehicle steering state signal, the user drive power command signal, and the target speed difference control strategy, synthesize the target speeds of the left front wheel and the right front wheel respectively, wherein the target speed difference control strategy is used to coordinate with the vehicle steering state signal to define the direction and magnitude relationship of the difference between the target speeds of the left front wheel and the right front wheel; Drive execution steps: Control the two independent motors to run at their respective target speeds.

2. The method according to claim 1, characterized in that, The user drift control command signal is a continuously variable signal; the control decision step includes: continuously adjusting the target speed difference control strategy according to the real-time value of the user drift control command signal.

3. The method according to claim 2, characterized in that, The target speed difference control strategy is embodied by a target speed difference direction coefficient. When the vehicle steering status signal indicates steering, the sign of the target speed difference direction coefficient is coordinated with the vehicle steering status signal to determine the direction of the target speed difference, and its absolute value is used to affect the magnitude of the target speed difference.

4. The method according to claim 3, characterized in that, The user drift control command signal comes from the opening signal of a dedicated drift control pedal; the value of the target speed difference direction coefficient is configured to change continuously with the change of the opening signal, and within the first change range of the opening signal, the absolute value of the coefficient decreases as the opening increases; within the second change range of the opening signal, the sign of the coefficient is opposite to that of the first change range, and its absolute value increases as the opening increases.

5. The method according to claim 4, characterized in that, Within the first variation range of the opening signal, corresponding to the normal driving mode, the target speed difference direction coefficient is configured such that when the vehicle steering status signal indicates steering, the target speed of the outer front wheel is higher than that of the inner front wheel; within the second variation range of the opening signal, corresponding to the drifting circle mode, the target speed difference direction coefficient is configured such that when the vehicle steering status signal indicates steering, the target speed of the inner front wheel is higher than that of the outer front wheel.

6. The method according to claim 5, characterized in that, The median value of the opening signal corresponds to the drift and sideslip mode; wherein, the median value is an intermediate value point or a narrow interval between the first and second variation intervals within the entire variation range of the opening signal; when the opening signal is within the value point or the narrow interval, the target speed difference direction coefficient is configured to maintain the target speed difference between the left front wheel and the right front wheel within a range where the absolute value is less than or equal to a preset threshold.

7. The method according to claim 1, characterized in that, The user drift control command signal is a multi-gear discrete signal, including at least a first gear corresponding to the normal driving mode, a second gear corresponding to the drift side-slip mode, and a third gear corresponding to the drift circle mode.

8. The method according to claim 7, characterized in that, In the first gear, when the vehicle steering status signal indicates steering, the target speed difference control strategy is configured to make the target speed of the outer front wheel higher than that of the inner front wheel; in the second gear, when the vehicle steering status signal indicates steering, the target speed difference control strategy is configured to maintain the target speed difference between the left and right front wheels within a range where the absolute value is less than or equal to a preset threshold; in the third gear, when the vehicle steering status signal indicates steering, the target speed difference control strategy is configured to make the target speed of the inner front wheel higher than that of the outer front wheel.

9. The method according to any one of claims 1 to 8, characterized in that, The user drive power command signal comes from the accelerator pedal, speed knob, or handle trigger.

10. A drift car, characterized in that, include: Frame; A front wheel steering assembly is mounted on the frame; the left and right front wheels are steerably mounted on the frame and are each mechanically driven independently by two separate motors. At least one rear wheel, mounted at the rear of the frame, is a swivel wheel without active steering; a vehicle status sensing module for acquiring vehicle steering status signals; a user command input module for acquiring user drive power command signals and user drift control command signals; a control mechanism including a processor, a memory, and a motor driver for driving the two independent motors, the memory storing a computer program, the processor being configured to execute the computer program to generate control commands, and controlling the operation of the two independent motors through the motor driver; wherein, the control mechanism is signal-connected to the vehicle status sensing module and the user command input module respectively, and is configured to execute the dual-motor speed cooperative control method as described in any one of claims 1 to 9 based on signals from the vehicle status sensing module and the user command input module to control the two independent motors.

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