Self-balancing control method applied to heteroaxial two-wheel vehicle

Abstract

The invention discloses a self-balancing control method applied to a heteroaxial two-wheeled vehicle, the vehicle carries a scissor-type double CMG module, the module comprises two CMG units, and the method comprises hardware decoupling: using the scissor-type double CMG to counteract course disturbance torque generated when the CMG works on a physical level; role separation: redefining a CMG system and a steering system; feedforward coordination: during turning, not depending on the CMG always generating a restoring moment to maintain a 0-degree inclination angle, calculating a steady-state inclination angle (phi lean) required at the speed and the steering angle through a dynamic model feedforward; and track planning: by coordinating track planning, it is ensured that the inclination action of the CMG and the steering action of the steering are perfectly synchronized in time, and balance is dynamically maintained. The problem of CMG saturation is solved, high-precision decoupling control is achieved, turning is smooth and safe, full-speed-domain coverage is achieved, and efficiency and energy saving are achieved.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of self-balancing vehicle control, in particular to a self-balancing control method applied to a two-wheeled vehicle with different axes. BACKGROUND

[0002] At present, the self-balancing control of the two-wheeled vehicle with different axes faces the following major challenges:

[0003] 1. Speed limit: the traditional balance method based on active steering is completely ineffective at low speed or at rest, and the vehicle cannot self-balance.

[0004] 2. CMG saturation and singularity problem: if only CMG is used for balancing, although static balance can be achieved, there is a fatal defect when continuously turning. The vehicle needs to maintain a steady tilt angle (φ lean ) If you try to use CMG to continuously output torque to resist centrifugal force, the frame of CMG will continuously rotate until it reaches its mechanical limit or singularity position (±90°), resulting in torque output saturation and the vehicle losing balance instantly.

[0005] 3. Strong coupling problem of the system: CMG and steering system are strongly coupled in dynamics, mainly in the following aspects:

[0006] CMG: When outputting roll balance torque, a coupled yaw disturbance torque is generated, causing the vehicle to yaw.

[0007] Steering: When performing steering (Yaw) action, a coupled roll torque is generated, causing the vehicle to tip over.

[0008] Timing mismatch: When turning, if the precession action of CMG does not match the timing of the steering action of the steering motor, for example, the CMG precession is too fast, and the steering is not in place, the vehicle will not be able to balance due to insufficient centripetal force, resulting in tipping inward.

[0009] The existing simple weighted fusion control does not fundamentally solve the fatal problems of CMG saturation and timing mismatch. SUMMARY

[0010] The purpose of the present application is to solve the problems raised in the background art, and to provide a self-balancing control method applied to a two-wheeled vehicle with different axes, which combines the self-balancing control method of control moment gyro (CMG) and active steering control, uses a double CMG array to realize hardware decoupling, and realizes the control strategy of stable turning in the full speed domain through coordinated trajectory planning.

[0011] To solve the above technical problems, the technical scheme of the present application is: a self-balancing control method applied to a two-wheel vehicle with different shafts, characterized in that: the vehicle is equipped with a scissor-type double-CMG module, the module comprising two CMG units, the rotation axes of the two units being parallel at the initial time and moving in opposite directions with the same speed during movement, and the control method comprising the following steps:

[0012] Step one, hardware decoupling: using the scissor-type double-CMG to offset the heading disturbance torque generated by the CMG during operation at the physical level;

[0013] Step two, role separation: redefining the CMG system and the steering system:

[0014] CMG system: only as a transient attitude regulator, its task is: ①, suppressing external transient roll interference; ②, providing a transient roll torque during the entry or exit stage of turning, actively driving the vehicle body to or back to the target inclination angle;

[0015] Steering system: as a steady-state trajectory controller, its task is: ①, assisting balance at high speed; ②, providing the required steering angle to generate a steady-state centripetal force during turning;

[0016] Step three, feedforward coordination: during turning, instead of relying on the CMG to always generate a restoring torque to maintain a 0-degree inclination angle, the required steady-state inclination angle (φ lean ) under the speed and steering angle is calculated through a dynamic model feedforward;

[0017] Step four, trajectory planning: through coordinated trajectory planning, the inclination action of the CMG and the steering action of the steering are perfectly synchronized in time, and balance is dynamically maintained.

[0018] In the above-mentioned self-balancing control method applied to a two-wheel vehicle with different shafts, when the controller needs a pure roll (Roll) torque (τ roll ), it commands the frames of the two CMGs to precess in opposite directions;

[0019] Where, the roll torque: τ roll = τ roll_a + τ roll_b (torque superposition);

[0020] Where, the heading disturbance: the reaction torques (τ yaw_a , τ yaw_b ) generated by the precession of the two frames are equal in size and opposite in direction, and cancel each other out on the vehicle.

[0021] In the above-mentioned self-balancing control method applied to a two-wheel vehicle with different shafts, when the vehicle is straight (v≥0), the target inclination angle φ setpoint= 0; when the roll angle φ detected by the IMU deviates from 0, the dual-CMG system performs the decoupling action of step one, outputting an instantaneous roll moment τ roll , the vehicle is righted; since the heading disturbance has been canceled by the hardware, this process does not affect the vehicle's straight-line travel.

[0022] In the above self-balancing control method applied to a two-wheel vehicle with different axes, when the system receives a turning instruction, i.e., a target steering angle δ target or a target heading angle speed :

[0023] S1: Calculate the feedforward target value

[0024] The controller calculates the steady-state tilt angle φ lean required for entering a steady-state turn based on the current vehicle speed v and the turning instruction through the vehicle dynamics model; φ lean is the angle at which the gravitational force and the centripetal force are balanced, at which angle the vehicle can maintain balance without the CMG outputting a moment;

[0025] S2: Coordinate trajectory planning

[0026] Instead of immediately issuing the (φ lean , δ target ) instruction, the controller plans a short transition time T;

[0027] The controller generates two smooth and dynamically coordinated time trajectories:

[0028] Among them, the tilt trajectory: φ cmd (t) is smoothly transitioned from 0 to φ lean in T time;

[0029] Among them, the steering trajectory: δ cmd (t), is smoothly transitioned from 0 to δ target in T time;

[0030] The coordination of these two trajectories ensures that at any time t during the transition, the centripetal force generated by steering δ cmd (t) can dynamically balance the gravitational tipping moment generated by tilt φ cmd (t);

[0031] S3: Trajectory tracking execution

[0032] The task of the CMG: the controller of the CMG acts as a trajectory tracker, whose instantaneous target is φ cmd (t), and the CMG will output an instantaneous moment to actively drive the vehicle body to accurately track the tilt trajectory φ cmd (t);

[0033] Task of steering: the steering motor controller also tracks delta cmd (t) trajectory

[0034] S4: entering steady state turning

[0035] When t > T, phi cmd is kept at phi lean , delta cmd is kept at delta target ; at this time, the vehicle tilt angle has reached phi lean , the tracking error of the CMG controller tends to zero; therefore, the torque output of the CMG reverses in advance to start deceleration, so that the precession angle can be maintained near a certain value during steady state turning; the task of the CMG automatically changes from driving tilt to perturbation suppression near phi lean ; since the CMG no longer continuously outputs torque during steady state turning, the frame angle does not drift, completely avoiding the problems of saturation and singularity.

[0036] In the self-balancing control method for a two-wheeled vehicle with different axes described above, when a turning end instruction is detected, the inverse process of steps S1 to S4 is performed; the controller plans phi cmd (t) from phi lean to 0, delta cmd (t) from delta target to 0; the CMG outputs a transient righting torque to smoothly bring the vehicle body back to the upright state, and the torque output is then zero again.

[0037] In the self-balancing control method for a two-wheeled vehicle with different axes described above, in step S1, the steady state tilt angle phi lean required to enter steady state turning is calculated by selecting the vehicle dynamics model phi 2 ≈ arctan (v lean / (gR)).

[0038] In the self-balancing control method for a two-wheeled vehicle with different axes described above, in step S2, the transition time T is planned to be 0.5 seconds.

[0039] In the self-balancing control method for a two-wheeled vehicle with different axes described above, in step S3, the controller of the CMG can select PID or LQR or SMC as the trajectory tracker.

[0040] The present application has the following beneficial effects:

[0041] 1. Solve the CMG saturation problem: the present application calculates the steady state tilt angle by feedforward and the CMG transient actuator strategy, so that the torque output of the CMG is stable near zero during steady state turning, and only works transiently when entering and leaving the turn, completely eliminating the risk of CMG saturation failure.

[0042] 2. High-precision decoupling control: By the hardware configuration of the scissors-type dual-CMG, the interference of the CMG with the heading is eliminated at the physical level, simplifying the control algorithm and improving the balancing accuracy.

[0043] 3. Smooth and safe turning: By coordinating the trajectory planning, the dynamic synchronization of tilting and turning is ensured, solving the risk of overturning caused by timing mismatch, making the turning process as smooth, active, and coordinated as human riding.

[0044] 4. Full-speed domain coverage: Combining the strong balancing ability of CMG at low speed / standstill and the efficiency of turning at high speed, and seamlessly connecting through coordination strategy, it realizes stable control from v=0 to high speed.

[0045] 5. High efficiency and energy saving: CMG only works in transient state, and the CMG torque output is close to zero (only self-rotation consumes energy) during most straight driving or steady turning, and the system energy efficiency is much higher than the scheme that requires continuous output of CMG torque. BRIEF DESCRIPTION OF DRAWINGS

[0046] Fig. 1 is the hardware architecture diagram of the vehicle system of the present application;

[0047] Fig. 2 is the working principle diagram of the scissors-type dual-CMG module of the present application;

[0048] Fig. 3 is the logic block diagram of the control system of the present application;

[0049] Fig. 4 is the control timing diagram of the turning-in phase of the present application. DETAILED DESCRIPTION

[0050] The present application is further described in conjunction with the accompanying drawings.

[0051] Please refer to Figs. 1 to 4 , the present application provides a self-balancing control method applied to an all-axle two-wheeled vehicle, characterized in that: the vehicle is equipped with a scissors-type dual-CMG module, which includes two CMG units, the self-rotation axes of the two units are parallel at the initial time, and the self-rotation axes of the two units rotate in opposite directions with the same speed during movement, and the control method includes the following steps:

[0052] Step 1, hardware decoupling: using the scissors-type dual-CMG to physically cancel the heading disturbance torque generated by the CMG during operation;

[0053] Step 2, role separation: redefine the CMG system and the turning system:

[0054] CMG system: as a transient attitude regulator, its task is: ①, to suppress external transient roll disturbance; ②, to provide transient roll moment to actively drive the vehicle to the target bank angle during the entry or exit of the corner;

[0055] Steering system: as a steady-state trajectory controller, its task is: ①, to assist balance at high speed; ②, to provide the required steering angle to generate steady-state centripetal force during cornering;

[0056] Step three, feedforward coordination: instead of relying on the CMG to generate a restoring moment to maintain a 0-degree bank angle all the time during cornering, the required steady-state bank angle (φ lean ) at this speed and steering angle is calculated through a dynamic model feedforward.

[0057] Step four, trajectory planning: through coordinated trajectory planning, the bank action of the CMG and the steering action of the steering are perfectly synchronized in time, dynamically maintaining balance.

[0058] The control method of the application includes but is not limited to the following steps:

[0059] Step one, system configuration and hardware decoupling

[0060] System configuration: the vehicle is equipped with a scissor-type double-CMG module, which includes two CMG units, the rotation axes of the two units are parallel at the initial time, and the rotation axes of the two units are opposite in precession direction and consistent in speed during movement.

[0061] Decoupling control: when the controller needs a pure roll moment (τ roll ), it commands the frames of the two CMGs to precess in opposite directions. Among them, the roll moment: τ roll = τ roll_a + τ roll_b (moment superposition); among them, the heading disturbance: the reaction moments (τ yaw_a , τ yaw_b ) generated by the precession of the two frames are equal in size and opposite in direction, and are mutually canceled on the vehicle.

[0062] Step two: straight line and disturbance suppression (CMG transient balance)

[0063] When the vehicle is driving straight (v≥0), the target bank angle φ setpoint of the CMG balance controller is 0; when the roll angle φ detected by the attitude sensor IMU deviates from 0 (for example, disturbed by crosswind), the double-CMG system performs the decoupling action of step one to output a transient roll moment τ Roll to right the vehicle. Since the heading disturbance has been canceled by hardware, this process will not affect the straight-line driving of the vehicle.

[0064] Step 3: Cornering control (coordination between trajectory planning and execution)

[0065] This is the core of the invention. When the system receives a cornering instruction, e.g., a target steering angle δ target or a target yaw rate ), the controller will:

[0066] S3.1: Calculate the feedforward target value

[0067] The controller calculates the steady-state bank angle φ lean required to enter a steady-state cornering based on the current vehicle speed v and the cornering instruction, through a vehicle dynamics model (e.g., φ 2 ≈ arctan(v lean / (gR));

[0068] where φ lean is the angle at which the gravitational force and the centripetal force are in equilibrium, at which angle the vehicle can maintain balance without the CMG needing to output a moment.

[0069] S3.2: Coordinate trajectory planning

[0070] Instead of immediately issuing the (φ lean , δ target ) instruction, the controller plans a short transition time T (e.g., 0.5 seconds);

[0071] The controller generates two smooth and dynamically coordinated time trajectories:

[0072] Banking trajectory: φ cmd (t) (smoothly transitions from 0 to φ lean in T time);

[0073] Steering trajectory: δ cmd (t) (smoothly transitions from 0 to δ target in T time);

[0074] The coordination between these two trajectories ensures that at any time t during the transition, the centripetal force generated by the steering δ cmd (t) dynamically balances the gravitational tipping moment generated by the banking φ cmd (t).

[0075] S3.3: Trajectory tracking execution

[0076] The task of the CMG: The controller of the CMG (e.g., PID / LQR / SMC) acts as a trajectory tracker, whose instantaneous target is φ cmd (t); the CMG will output an instantaneous moment to actively drive the vehicle body to accurately track this banking trajectory φ cmd (t);

[0077] Task of steering: the steering motor controller also tracks δ cmd (t) trajectory.

[0078] S3.4: entering steady turn

[0079] When t > T, φ cmd is kept at φ lean , δ cmd is kept at δ target . At this time, the vehicle tilt angle has reached φ lean , the tracking error of the CMG controller tends to zero; therefore, the torque output of the CMG reverses in advance to start deceleration, so that the precession angle can be maintained around a certain value during the steady turn;

[0080] The task of the CMG automatically changes from driving tilt to perturbation suppression around φ lean ; since the CMG no longer continuously outputs torque during the steady turn, the frame angle does not drift, completely avoiding saturation and singularity problems.

[0081] Step four: exit the turn

[0082] When the end of turn command is detected, the reverse process of step three is performed:

[0083] The controller plans φ cmd (t) from φ lean to 0, δ cmd (t) from δ target to 0; the CMG outputs a transient righting torque to smoothly bring the vehicle body back to the upright state, and the torque output is then zero again.

[0084] The above describes in detail a self-balancing control method for a heteroaxial two-wheeled vehicle provided by an embodiment of the present application. The principles and implementation modes of the present application are described using specific examples. The above description of the embodiments is only used to help understand the technical solutions disclosed by the present application. Meanwhile, for those skilled in the art, according to the idea of the present application, the specific implementation modes and application ranges can be changed. In summary, the content of the present description should not be understood as limiting the present application.

Claims

1. A self-balancing control method applied to an in-line two-wheeled vehicle, characterized in that: The vehicle is equipped with a scissor dual-CMG module, which includes two CMG units, the rotation axes of the two units are parallel at the initial time, and the directions of the precession of the rotation axes of the two units are opposite and the speeds are consistent in motion, and the control method comprises the following steps: Step one, hardware decoupling: using the scissor dual-CMG to offset the heading disturbance torque generated when the CMG works; Step two, role separation: redefine the CMG system and the steering system: CMG system: only as a transient attitude regulator, its task is: ①, suppress external transient roll disturbance; ②, in the entry or exit stage of turning, provide transient roll torque, actively drive the vehicle body to the target inclination angle or back to the target inclination angle; Steering system: as a steady-state trajectory controller, its task is: ①, auxiliary balance at high speed; ②, provide the required steering angle to generate steady-state centripetal force when turning; Step three, feedforward coordination: instead of relying on the CMG to always produce a restoring moment to maintain a 0 degree tilt angle, the feedforward calculates the steady state tilt angle (φ lean ) required for the given velocity and steering angle using a dynamic model. Step four, trajectory planning: through the coordination of trajectory planning, ensure that the inclination action of the CMG and the steering action of the steering are perfectly synchronized in time, and dynamically maintain balance.

2. The self-balancing control method for a non-axle two-wheeled vehicle according to claim 1, characterized in that: When the controller system requires a pure roll moment (τ roll ), it commands the frames of both CMGs to precess in opposite directions; where the roll moment: τ roll = τ roll_a + τ roll_b (moment superposition); Wherein, the heading disturbance: two frame precession generated reaction torque (τ yaw_a ,τ yaw_b ) equal in size, opposite direction, on the car body to offset each other.

3. The self-balancing control method for a non-axle two-wheeled vehicle according to claim 1, characterized in that: When the vehicle is driving straight (v≥0), the target tilt angle φ setpoint =0; when the attitude sensor IMU detects that the roll angle φ deviates from 0, the double-CMG system performs the decoupling action of step one, outputting a moment τ roll , which rightens the vehicle; since the heading disturbance has been canceled by hardware, this process will not affect the straight driving of the vehicle.

4. The self-balancing control method for a non-axle two-wheeled vehicle according to claim 1, characterized in that: When the system receives a turn instruction, i.e. a target steering angle δ target or a target yaw rate : S1: Calculate the feedforward target value The controller calculates the steady-state tilt angle φ required to enter a steady-state turn from the current vehicle speed v and the turn command, through a vehicle dynamics model lean ; φ lean is the angle at which the gravity and centripetal forces are balanced, at which angle the CMG does not need to output a moment to maintain the vehicle in balance; S2: Coordinate trajectory planning Instead of immediately issuing the (φ lean ,δ target ) command, the controller plans a short transition time T; The controller generates two smooth and dynamically coordinated time trajectories: wherein the tilted trajectory: φ cmd (t) is a smooth transition from 0 to φ lean over T time Wherein, the steering trajectory: δ cmd (t), is smoothly transitioned from 0 to δ target ; The coordination of the two trajectories ensures that at any instant t during the transition, the steering δ cmd (t) the resulting centripetal force, dynamically balances the tilt φ cmd (t) the resulting gravitational tipping moment; S3: Trajectory tracking execution Task of CMG: The controller of CMG acts as a trajectory tracker, whose instantaneous target is φ cmd (t), the CMG will output an instantaneous torque to actively drive the body to track this tilted trajectory φ cmd (t) precisely; Task of steering: The steering motor controller also tracks δ cmd (t) trajectory; S4: Enter steady-state turning φ cmd is kept at φ lean , δ cmd is kept at δ target ; at this time, the vehicle tilt angle has reached φ lean , the tracking error of the CMG controller tends to zero; therefore, the torque output of the CMG reverses in advance to start deceleration, so that the precession angle can be maintained near a certain value during steady turning; the task of the CMG is automatically changed from driving tilt to perturbation suppression near φ lean , and since the CMG no longer continuously outputs torque during steady turning, the frame angle does not drift, completely avoiding saturation and singularity problems.

5. The self-balancing control method for a non-axle two-wheeled vehicle according to claim 3, characterized in that: When a turn end instruction is detected, the inverse of steps S1 to S4 is executed; the controller plans φ cmd (t) from φ lean back to 0, δ cmd (t) from δ target back to 0; the CMG outputs a moment of righting torque instantaneously, smoothly bringing the vehicle body back to upright, with the moment output subsequently returning to zero again.

6. The self-balancing control method for a non-axle two-wheeled vehicle according to claim 4, characterized in that: In step S1 the steady state tilt angle φ lean ≈ arctan(v 2 / (gR)) required for entering a steady state turn is calculated. lean ​ 7. The self-balancing control method for a non-axle two-wheeled vehicle according to claim 4, characterized in that: In step S2, the transition time T is planned to be 0.5 seconds.

8. The self-balancing control method for a non-axle two-wheeled vehicle according to claim 4, characterized in that: In step S3, the controller of the CMG can select PID or LQR or SMC as the trajectory tracker.

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