A dual-joint series driving land-air dual-mode chassis system and control method

Abstract

The application discloses a double-joint series driving land-air dual-mode chassis system and a control method, which is applied to a flying car and comprises a multi-source sensing unit, a central computing unit, a vehicle body base, a composite joint driving assembly, a suspension swing arm, a mode switching assembly and a wheel-wing integrated assembly. The suspension swing arm, the composite joint driving assembly and the leg support on the vehicle body base form a triangular bearing configuration, so that the number of suspension parts and the mechanism mass are reduced. The pre-tightening force of the coil spring can bear the static gravity of the vehicle body, the gravity of the joint servo motor is unloaded, the static heat dissipation of the chassis system is reduced, the passive mechanical stiffness of the spring and the virtual impedance stiffness of the motor form a parallel elastic system, and the total equivalent stiffness can be continuously adjusted within a certain range.

Description

Technical Field

[0001] This invention belongs to the field of flying car and wheeled-legged robot technology, specifically relating to a dual-joint serial drive land-air dual-modal chassis system and control method. Background Technology

[0002] Against the backdrop of vigorous development of the low-altitude economy, flying cars, which combine land driving and air flight capabilities, have attracted widespread attention. However, existing wheel-wing integrated flying cars have significant shortcomings in terms of land-air connection mechanisms: on the one hand, traditional wheel-wing connection units rely solely on a single servo motor to complete land-air mode switching, resulting in rigid connections and a lack of shock absorption devices; or they are only equipped with passive damping suspension, which is insufficient in terms of vibration reduction when facing complex terrain or landing impacts, making them highly susceptible to damage to the internal transmission gears and rotor structure; on the other hand, the field of wheel-legged robots has verified the superiority of serial joint structures in ground vibration reduction and landing buffering. Through the coordinated cooperation of algorithms and joint motors, inertial unloading and active suspension functions can be effectively achieved, and they are more compact and lightweight than complex multi-link active suspension structures, but the above solutions have not yet been systematically applied to the design of flying car chassis.

[0003] Therefore, developing an active suspension system for flying cars that balances ground driving comfort, landing buffer energy absorption, and flexible switching between land and air modes has significant engineering value. Summary of the Invention

[0004] In view of the shortcomings of the prior art, the purpose of this invention is to provide a dual-joint series-driven land-air dual-mode chassis system and control method. By working together with the composite drive joint and the end-mode switching joint, the invention solves the problem that a single mechanism in the prior art cannot simultaneously achieve smooth ground driving, landing buffer energy absorption and flexible land-air mode switching.

[0005] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0006] This invention discloses a dual-joint tandem-driven land-air dual-modal chassis system for use in flying cars, comprising: a multi-source sensing unit, a central computing unit, a vehicle chassis, a composite joint drive assembly, suspension arms, a mode-switching assembly, and a wheel-wing integrated assembly; wherein...

[0007] The multi-source sensing unit is used to collect vehicle attitude data and ground clearance data in real time and send them to the central computing unit.

[0008] The central computing unit, installed in the vehicle body base, is used to output control commands to the composite joint drive assembly and the mode switching assembly;

[0009] One end of the composite joint drive assembly is fixedly connected to the vehicle body base, and the other end is rigidly connected to one end of the suspension swing arm;

[0010] The other end of the suspension arm is connected to the mode switching component;

[0011] The mode switching component is connected to the wheel-wing integrated component.

[0012] Furthermore, the multi-source sensing unit includes a six-axis inertial measurement unit (IMU) installed inside the vehicle body base and a millimeter-wave radar rangefinder installed below the vehicle body base.

[0013] Furthermore, the central computing unit performs Kalman filtering fusion on the data sent by the multi-source sensing unit, estimates the vehicle's vertical acceleration, pitch angle, roll angle, and ground clearance of each wheel in real time, and makes motion mode decisions in conjunction with the target mission instructions, outputting corresponding joint control commands.

[0014] Furthermore, each of the four corners of the vehicle body base is provided with a set of mounting positions for fixing the leg bracket. One end of the leg bracket is fixedly connected to the vehicle body base, and the other end is rigidly connected to the composite joint drive assembly. Through the transfer of the leg bracket, the joint drive load is effectively distributed to the vehicle body base.

[0015] Furthermore, the composite joint drive assembly includes a joint servo motor, an absolute encoder, and an elastic damping assembly; the joint servo motor and the elastic damping assembly are coaxially connected in parallel.

[0016] The stator flange of the joint servo motor is rigidly connected to the leg support of the vehicle body base, and the output shaft of the joint servo motor is rigidly connected to one end of the suspension swing arm via a keyway, forming an active drive link from the vehicle body base to the suspension swing arm. In position servo mode, the joint servo motor drives the suspension swing arm to deflect in order to adjust the vehicle body's ground clearance and thrust direction. In impedance control mode, based on the angle and angular velocity signals fed back by the absolute encoder and the vehicle body attitude data fed back by the multi-source sensing unit, the dynamically adjustable impedance torque is calculated and output in real time.

[0017] The absolute encoder is coaxially integrated into the output shaft of the joint servo motor. The housing of the absolute encoder is fixedly mounted on the end cover of the joint servo motor, keeping it relatively stationary with respect to the vehicle body base. The detection shaft of the absolute encoder is coaxially fixed to the output shaft of the joint servo motor and rotates synchronously with the suspension arm. The absolute encoder collects the absolute angular position signal and instantaneous angular velocity signal of the suspension arm relative to the leg support, which are used as state feedback inputs for the stiffness and damping terms in impedance control. The central computing unit calculates the real-time deformation of the elastic damping component based on the absolute angle signal, and then obtains the restoring torque of the elastic damping component acting on the suspension arm, which is used to realize closed-loop torque feedback and feedforward compensation of the impedance control algorithm during active obstacle avoidance or landing buffering.

[0018] The elastic damping assembly includes: a shock absorber and a coil spring sleeved on the shock absorber; one end of the shock absorber is hinged to a first hinge lug on the leg support, and the other end is hinged to a second hinge lug in the middle of the suspension arm, with both hinge axes parallel to the axis of the output shaft of the joint servo motor; the coil spring is installed in a pre-compressed state between the spring seats at both ends of the shock absorber; when the suspension arm swings around the output shaft, the distance between the two hinge lugs changes with the swing angle, and the coil spring generates a restoring torque on the suspension arm around the axis of the output shaft, while the shock absorber simultaneously generates a damping torque that resists the swing of the suspension arm.

[0019] Furthermore, the resistive torque is composed of the superposition of the following three components:

[0020] Virtual inertial torque proportional to the angular acceleration of the suspension arm swinging about the output shaft , It is used to adjust how quickly the suspension control arm responds to changes in acceleration;

[0021] Virtual damping torque proportional to the angular velocity of the suspension arm swinging about the output shaft , It is used to control the rate of dissipation of kinetic energy;

[0022] Virtual stiffness moment proportional to the angular deviation of the suspension control arm , It is used to adjust the magnitude of the restoring torque after deviating from the target angle;

[0023] in, The angle of rotation of the suspension arm around the output shaft, measured by an absolute encoder; This is the angular velocity at that turning angle; The angular acceleration at that angle is expressed as angular velocity. Acquisition of differential or six-axis inertial measurement data; To balance the target angle; These are virtual moment of inertia, virtual torsional damping, and virtual torsional stiffness, respectively. When there is a landing impact or road bumps, the joint servo motor actively adjusts the output torque according to the three components of the impedance torque mentioned above, so as to adapt to the impact force and make the suspension arm deflect and yield in the direction of the impact. During the reset phase of the suspension arm, the damping component is used to absorb and suppress the oscillation generated when the coil spring releases its elastic potential energy, thereby achieving attitude stability and smooth buffering in the landing mode.

[0024] Furthermore, the suspension arm is made of carbon fiber composite material, with a hollow interior forming a wiring channel. One end is connected to the output shaft of the joint servo motor via a keyway, and the other end is connected to the mode switching component via a U-shaped mounting bracket.

[0025] Furthermore, the mode switching component includes: a joint tilting servo and a mechanical locking pin;

[0026] The joint-mounted tilt servo is a servo servo with an internally integrated reduction gear set, including a servo housing and an output shaft. A connecting flange is fixedly provided at the end of the output shaft. The servo housing is fixedly installed in a U-shaped mounting base. The axis of the connecting flange is perpendicular to the longitudinal centerline of the suspension arm and is located in the swing plane of the suspension arm. The connecting flange is rigidly connected to the wheel-wing integrated assembly, so that the wheel-wing integrated assembly can rotate as a whole around the output shaft axis of the joint-mounted tilt servo. When the suspension arm is in a vertical position, the tilt axis is horizontal and parallel to the longitudinal direction of the vehicle body. The wheel-wing integrated assembly can switch between a ground driving posture with the wheel surface vertical and a flight posture with the wheel surface horizontal by rotating 90°.

[0027] The mechanical locking pin adopts an electromagnetic pin structure, consisting of a drive housing and a telescopic rod driven by it. The drive housing integrates an electromagnetic coil and a return spring. The root of the telescopic rod is connected to the return spring, and the middle part passes through the electromagnetic coil. The drive housing is rigidly installed on the inner wall of the U-shaped mounting base and is located diagonally above the joint tilting servo. The axis of the telescopic rod is parallel to the output shaft axis of the joint tilting servo.

[0028] Furthermore, the wheel-wing integrated assembly includes: a hub drive motor stator bracket, a hub drive motor, an outer tire, a propulsion motor, and blades;

[0029] The hub drive motor stator bracket includes: a flange and a central cylinder; the flange and the connecting flange are rigidly connected coaxially, and the central cylinder and the flange are rigidly connected coaxially; a propulsion motor is coaxially installed in the inner cavity of the central cylinder, the output shaft of the propulsion motor extends out of the central cylinder and is driven and connected to the blades, and the blades are located within the inner circle of the outer tire rim when retracted; the stator of the hub drive motor is fixed to the outer circumference of the central cylinder, and the outer rotor of the hub drive motor is supported on the outer circular surface of the central cylinder by two sets of deep groove ball bearings, and the outer periphery of the outer rotor is rigidly connected to the inner rim of the outer tire; two locking grooves on the hub drive motor stator bracket are formed on the side of the flange.

[0030] This invention also provides a control method for a dual-joint tandem-driven land-air dual-modal chassis system. Based on the above system, the method steps are as follows:

[0031] 1) Takeoff control from land to air;

[0032] 11) The central computing unit sends a lifting command to the joint servo motor in the composite joint drive assembly. The joint servo motor drives the suspension arm to swing downward relative to the vehicle body base, overcoming the weight of the entire vehicle and smoothly lifting the vehicle body base.

[0033] 12) The absolute encoder collects the absolute angle of the suspension arm in real time during the downward swing of the suspension arm and sends the angle data to the central computing unit. When the absolute angle reaches the target position corresponding to the set takeoff ground clearance, the central computing unit controls the joint servo motor to enter the position holding mode and uses the electromagnetic holding torque of the motor to rigidly lock the current attitude of the suspension arm.

[0034] 13) After the central computing unit confirms that the vehicle height is locked, it sends an unlocking signal to the mode switching component, controls the mechanical locking pin to be energized and performs a retraction action, so that the telescopic rod exits the locking groove, thereby releasing the physical constraint on the rotational degree of freedom of the wheel-wing integrated component;

[0035] 14) The articulated servo drive wheel-wing integrated assembly smoothly and uniformly rotates 90 degrees from a ground driving attitude perpendicular to the ground until it reaches a horizontal flight attitude parallel to the ground.

[0036] 15) The central computing unit controls the cutting off of the electromagnetic power supply to the mechanical locking pin. The mechanical locking pin is ejected by the driving force of the return spring and embedded in the locking groove corresponding to the horizontal flight attitude, realizing the mechanical rigid locking between the wheel-wing integrated component and the suspension swing arm, so as to isolate the impact and wear of the high-frequency flight vibration generated by the propeller of the flying car on the internal reduction gear of the joint rollover servo.

[0037] 2) Landing cushioning control;

[0038] 21) The multi-source sensing unit collects the real altitude and descent rate of the flying car in real time during the landing process. When the real altitude is equal to the landing value, the central computing unit sends an unlocking command signal to the mode switching component. The mechanical locking pin is released. After the pin is released, the joint flip servo drives the wheel-wing integrated component to smoothly and uniformly flip 90 degrees from the flight attitude parallel to the ground until it reaches the ready landing attitude perpendicular to the ground.

[0039] 22) When the outer tire touches the ground, the coil spring and shock absorber undergo passive compression deformation to absorb the landing impact force and complete the first stage of mechanical buffer protection. At the same time, the absolute encoder synchronously collects the angle deviation of the suspension arm caused by the compression of the elastic damping component and sends it to the central computing unit. The central computing unit controls the release of the original position holding mode of the joint servo motor, switches the joint servo motor to impedance control mode, and retrieves the impedance parameter group corresponding to the landing impact condition from the pre-calibrated parameter table.

[0040] 23) Calculation of impedance torque for joint servo motors The calculation formula is as follows:

[0041] ;

[0042] in, This represents the restoring torque of the current elastic damping component; in this impedance control mode, the joint servo motor drives the suspension arm to retract upwards to execute the knee flexion action; during this stage, virtual torsional damping... Large values ​​are chosen to provide strong energy dissipation, virtual torsional stiffness A small value makes the system exhibit compliant characteristics in the impact direction, and the virtual moment of inertia The value is set too high to smooth the sudden peak of the impact acceleration; the active damping torque generated by the joint servo motor and the restoring torque of the coil spring and shock absorber form a parallel synergy in mechanical transmission, and together dissipate the inertial kinetic energy from the descent of the vehicle body base;

[0043] 24) As the landing kinetic energy gradually decays and dissipates, the central computing unit dynamically adjusts the impedance parameter set for the landing impact condition in stages based on the vehicle attitude data collected by the multi-source sensing unit. During the rebound suppression phase after the impact peak, it maintains high virtual torsional damping. To suppress the rebound force generated when the coil spring and shock absorber release their elastic potential energy after reaching their compression limit, the virtual torsional stiffness is gradually increased. The suspension arms are guided to smoothly return to the target cruise angle; parameter switching adopts first-order inertial transition to avoid step jumps in control torque; when the suspension arm angle returns to the target value corresponding to the preset ground cruise clearance, the impedance parameter group is switched to the ground driving mode parameter group, ultimately achieving a soft landing of the flying car.

[0044] Furthermore, the impedance parameter set is determined as follows:

[0045] A beetle-like biomimetic optimization algorithm is used to encode the 12 impedance parameters to be optimized into a 12-dimensional position vector. A comprehensive performance evaluation function J is constructed as the fitness function. The comprehensive performance evaluation function J simultaneously considers the root mean square value and peak value of the vehicle's vertical acceleration, the overshoot of the swing arm angle, and the motor energy consumption. The impact condition of the flying car landing at a set descent speed is simulated in the simulation environment. The smaller the value of the comprehensive performance evaluation function J, the better the comprehensive performance.

[0046] The search direction is determined by applying symmetrical perturbations to both sides of the current parameter vector and comparing the differences in the values ​​of the comprehensive performance evaluation function J at two points. The parameter vector is updated in the direction where the value of J is lower, and the search step size gradually decreases with the number of iterations until it converges to the optimal parameters. The above optimization process is run under different working conditions (different descent speeds, vehicle weights, etc.) to establish a mapping dataset of working conditions and optimal parameters.

[0047] Furthermore, the mapping dataset obtained by the beetle whisker biomimetic optimization algorithm is used to train a BP neural network. The input of this network is the current working condition characteristics, and the output is a total of 12 impedance parameters of four sets of composite joint drive components. Before training, the initial weights and thresholds of the BP neural network are pre-optimized using the beetle whisker biomimetic optimization algorithm to improve the convergence accuracy of the network. The central computing unit uses the optimized BP neural network to predict the corresponding impedance parameter set based on the data collected by the multi-source sensing unit in each control cycle and calculates the control torque.

[0048] The beneficial effects of this invention are:

[0049] 1. This invention constructs a triangular load-bearing configuration by combining the suspension arm, composite joint drive assembly, and leg support, thereby reducing the number of suspension components and the mass of the mechanism. The preload of the coil spring can bear the static weight of the vehicle body, thereby unloading the weight of the joint servo motor and helping to reduce the static heat dissipation of the chassis system. At the same time, the passive mechanical stiffness of the spring and the virtual impedance stiffness of the motor form a parallel elastic system, and the total equivalent stiffness can be continuously adjusted within a certain range.

[0050] 2. This invention connects the joint servo motor and the joint tilting servo motor in series via a suspension swing arm. During landing or off-road conditions, the elastic damping component first absorbs the peak impact (first-stage passive mechanical buffer), and then the joint servo motor outputs dynamic torque according to the impedance torque formula (second-stage active damping buffer). The two stages work together to stop the ground impact force at the root of the transmission chain, effectively reducing the risk of the impact force being transmitted to the end joint tilting servo motor and improving the service life of the transmission system.

[0051] 3. This invention combines impedance control with a rotary joint structure, enabling active vibration isolation during ground travel and compliant buffering during landing impact to be achieved within a unified impedance control framework, with the only difference being the different values ​​of the parameter set. During ground travel, a parameter configuration with medium damping and medium stiffness is used to focus on vibration isolation, while during landing impact, a parameter configuration with high damping and low stiffness is switched to focus on energy absorption, avoiding logical conflicts and sudden torque changes when switching between different control modes.

[0052] 4. This invention introduces a beetle whisker-inspired bio-optimized BP neural network impedance method. For ground driving modes such as cruising on smooth roads and off-road bumpy conditions, as well as landing modes with different descent speeds and impact intensities, the 12-dimensional parameter space is first optimized using a beetle whisker-inspired optimization algorithm to obtain the optimal parameter set for each condition. Then, a BP neural network is used to establish a mapping from condition characteristics to impedance parameters, enabling the system to adjust impedance parameters in real time when switching between land and air dual-mode conditions, thereby minimizing parameter mismatch and torque abrupt changes during mode switching. Attached Figure Description

[0053] Figure 1This is a schematic diagram of the overall structural principle of the system of the present invention;

[0054] Figure 2 This is a schematic diagram of the composite joint drive assembly in this invention;

[0055] Figure 3 for Figure 2 AA section view;

[0056] Figure 4 This is a schematic diagram of the modal switching component and the wheel-wing integrated component in this invention;

[0057] Figure 5 for Figure 4 View from direction A;

[0058] In the diagram: 1-Multi-source sensing unit, 11-Six-axis inertial measurement unit, 12-Millimeter-wave radar rangefinder, 2-Central computing unit, 3-Vehicle base, 31-Leg bracket, 4-Composite joint drive assembly, 41-Joint servo motor, 411-Stator flange, 412-Output shaft, 42-Absolute encoder, 43-Elastic damping assembly, 431-Shock absorber, 432-Coil spring, 5-Suspension swing arm, 51-U-shaped mounting base, 6-Mode switching assembly, 61-Joint tilting servo, 611-Connecting flange, 62-Mechanical locking pin, 621-Drive housing, 622-Telescopic rod, 7-Wheel-wing integrated assembly, 71-Wheel hub drive motor stator bracket, 711-Locking groove, 712-Center cylinder, 713-Flange, 72-Wheel hub drive motor, 73-Outer tire, 74-Propulsion motor, 75-Blade. Detailed Implementation

[0059] To facilitate understanding by those skilled in the art, the present invention will be further described below with reference to embodiments and accompanying drawings. The content mentioned in the embodiments is not intended to limit the present invention.

[0060] Reference Figures 1 to 5 As shown, the present invention discloses a dual-joint tandem-driven land-air dual-modal chassis system, applied in a flying car, comprising: a multi-source sensing unit 1, a central computing unit 2, a vehicle body base 3, a composite joint drive assembly 4, a suspension swing arm 5, a mode switching assembly 6, and a wheel-wing integrated assembly 7; wherein,

[0061] Multi-source sensing unit 1 is used to collect vehicle posture data and ground clearance data in real time and send them to central computing unit 2;

[0062] In the example, the multi-source sensing unit 1 includes a six-axis inertial measurement unit (IMU) 11 installed inside the vehicle body base 3 and a millimeter-wave radar rangefinder 12 installed below the vehicle body base 3.

[0063] The central computing unit 2, installed in the vehicle body base 3, is used to output control commands to the composite joint drive assembly 4 and the mode switching assembly 6. The central computing unit 2 performs Kalman filtering fusion on the data sent by the multi-source sensing unit 1, estimates the vertical acceleration, pitch angle, roll angle and ground clearance of each wheel in real time, and makes motion mode decisions in combination with the received target task commands, and outputs the corresponding joint control commands.

[0064] The vehicle body base 3 has a set of mounting positions at each of its four corners for fixing the leg brackets 31. One end of the leg bracket is fixedly connected to the vehicle body base 3, and the other end is rigidly connected to the composite joint drive assembly 4. Through the transfer of the leg brackets 31, the joint drive load is effectively distributed to the vehicle body base 3.

[0065] One end of the composite joint drive assembly 4 is fixedly connected to the vehicle body base 3, and the other end is rigidly connected to one end of the suspension swing arm 5;

[0066] Specifically, the composite joint drive assembly 4 includes: a joint servo motor 41, an absolute encoder 42, and an elastic damping assembly 43; the joint servo motor 41 and the elastic damping assembly 43 are coaxially connected in parallel.

[0067] The stator flange 411 of the joint servo motor 41 is rigidly connected to the leg bracket 31 of the vehicle body base 3. The output shaft 412 of the joint servo motor 41 is rigidly connected to one end of the suspension swing arm 5 via a keyway, forming an active drive link from the vehicle body base 3 to the suspension swing arm 5. In position servo mode, the joint servo motor 41 drives the suspension swing arm 5 to deflect in order to adjust the vehicle body ground clearance and thrust direction. In impedance control mode, based on the angle and angular velocity signals fed back by the absolute encoder 42 and the vehicle body attitude data fed back by the multi-source sensing unit 1, the central computing unit 2 calculates and outputs a dynamically adjustable impedance torque in real time.

[0068] The absolute encoder 42 is coaxially integrated on the output shaft of the joint servo motor 41. The housing of the absolute encoder 42 is fixedly mounted on the end cover of the joint servo motor 41, keeping it relatively stationary with respect to the vehicle body base 3. The detection shaft of the absolute encoder 42 is coaxially fixedly connected to the output shaft 412 of the joint servo motor 41, and rotates synchronously with the suspension arm 5. The absolute encoder 42 collects the absolute angular position signal and instantaneous angular velocity signal of the suspension arm 5 relative to the leg support, which are used as state feedback inputs for the stiffness and damping terms in impedance control. The central computing unit 2 calculates the real-time deformation of the elastic damping component 43 based on the absolute angular signal, and then obtains the restoring torque of the elastic damping component 43 acting on the suspension arm 5, which is used to realize closed-loop torque feedback and feedforward compensation of the impedance control algorithm during active obstacle avoidance or landing buffering.

[0069] The restoring torque is equal to the product of the sum of the spring force of the helical spring 432 and the damping force of the shock absorber 431 in the elastic damping assembly 43 and the lever arm. The spring compression and the deformation rate of the shock absorber are obtained by the absolute angle signal according to the geometric installation relationship of the elastic damping assembly 43.

[0070] The elastic damping assembly 43 includes: a shock absorber 431 and a coil spring 432 sleeved on the shock absorber 431; one end of the shock absorber 431 is hinged to a first hinge lug provided on the leg bracket 31, and the other end is hinged to a second hinge lug provided in the middle of the suspension arm 5, and the axes of both hinges are parallel to the axis of the output shaft 412 of the joint servo motor 41; the coil spring 432 is installed in a pre-compressed state between the spring seats at both ends of the shock absorber 431; when the suspension arm 5 swings around the output shaft 412, the distance between the two hinge lugs changes with the swing angle, and the coil spring 432 generates a restoring torque on the suspension arm 5 around the axis of the output shaft 412, while the shock absorber 431 simultaneously generates a damping torque that resists the swing of the suspension arm 5.

[0071] In a static state, the preload of the coil spring 432 bears part of the vehicle's weight, thus unloading the weight of the joint servo motor 41. At the moment of contact with the ground, the coil spring 432 and the shock absorber 431 act as the first-stage passive buffer elements to absorb the peak impact energy. During the impedance control phase, the passive mechanical stiffness of the coil spring 432 and the virtual stiffness provided by the joint servo motor 41 are superimposed in parallel, and the passive mechanical damping of the shock absorber 431 and the virtual damping provided by the joint servo motor 41 are superimposed in parallel. The elastic damping component 43 is located in the swing plane of the suspension arm 5 and avoids the flipping space of the wheel-wing integrated component 7.

[0072] The other end of the suspension arm 5 is connected to the mode switching component 6;

[0073] Specifically, the resistive torque is composed of the following three superimposed components:

[0074] Virtual inertial torque proportional to the angular acceleration of the suspension arm 5 swinging about the output shaft 412 , It is used to adjust how quickly the suspension arm 5 responds to changes in acceleration;

[0075] Virtual damping torque proportional to the angular velocity of the suspension arm 5 swinging about the output shaft 412 , It is used to control the rate of dissipation of kinetic energy;

[0076] Virtual stiffness moment proportional to the angular deviation of suspension arm 5 , It is used to adjust the magnitude of the restoring torque after deviating from the target angle;

[0077] in, The angle of rotation of the suspension arm 5 around the output shaft 412 is measured by an absolute encoder. This is the angular velocity at that turning angle; The angular acceleration at that angle is expressed as angular velocity. Acquisition of differential or six-axis inertial measurement data; To balance the target angle; These are virtual moment of inertia, virtual torsional damping, and virtual torsional stiffness, respectively. When there is a landing impact or road bumps, the joint servo motor 41 actively adjusts the output torque according to the three components of the impedance torque mentioned above, and makes the suspension arm 5 deflect and yield in the direction of the impact in accordance with the impact force. During the reset phase of the suspension arm 5, the damping component is used to absorb and suppress the oscillation generated when the coil spring 432 releases its elastic potential energy, thereby achieving attitude stability and smooth buffering in the landing mode.

[0078] In the example, the suspension arm 5 is made of carbon fiber composite material, and its hollow interior forms a wiring channel. One end is connected to the output shaft of the joint servo motor 41 through a keyway, and the other end is connected to the mode switching component 6 through a U-shaped mounting base 51.

[0079] Modal switching component 6 is connected to wheel-wing integrated component 7;

[0080] The mode switching component 6 includes: a joint tilting servo motor 61 and a mechanical locking pin 62;

[0081] The joint-rotating servo 61 is a servo servo with an internally integrated reduction gear set, including a servo housing and an output shaft. A connecting flange 611 is fixedly provided at the end of the output shaft. The servo housing is fixedly installed in the U-shaped mounting base 51. The axis of the connecting flange 611 (i.e., the output shaft axis of the joint-rotating servo 61) is perpendicular to the longitudinal centerline of the suspension swing arm 5 and is located in the swing plane of the suspension swing arm 5. The connecting flange 611 is rigidly connected to the wheel-wing integrated assembly 7, so that the wheel-wing integrated assembly 7 can rotate as a whole around the output shaft axis of the joint-rotating servo 61. When the suspension swing arm 5 is in a vertical position, the rotation axis is horizontal and parallel to the longitudinal direction of the vehicle body. The wheel-wing integrated assembly 7 can switch between a ground driving posture with the wheel surface vertical and a flight posture with the wheel surface horizontal by rotating 90°.

[0082] The mechanical locking pin 62 adopts an electromagnetic pin structure, consisting of a drive housing 621 and a telescopic rod 622 driven by it. The drive housing 621 integrates an electromagnetic coil and a return spring. The root of the telescopic rod 622 is connected to the return spring, and the middle part passes through the electromagnetic coil. The drive housing 621 is rigidly installed on the inner wall of the U-shaped mounting base 51 and is located diagonally above the joint tilting servo 61. The axis of the telescopic rod 622 is parallel to the output shaft axis of the joint tilting servo 61.

[0083] When mode switching is required, the electromagnetic coil is energized, generating electromagnetic attraction to drive the telescopic rod 622 to retract inward against the elastic force of the return spring, disengaging from the locking groove 711 on the stator bracket 71 of the hub drive motor, thus releasing the mechanical constraint on the rotational freedom of the wheel-wing integrated assembly 7. When the wheel-wing integrated assembly 7 is driven to a preset angle by the joint flip servo 61, the power supply to the electromagnetic coil is cut off, and the telescopic rod 622 extends outward along its axis under the elastic restoring force of the return spring, embedding into the corresponding locking groove 711 on the stator bracket 71 of the hub drive motor, thereby establishing a rigid limiting connection between the suspension arm 5 and the wheel-wing integrated assembly 7, preventing the mechanism from loosening due to flight vibration or ground bumps.

[0084] On the side of the hub drive motor stator bracket 71, locking grooves 711 are provided at 0° and 90° positions, with the output shaft of the joint tilting servo motor 61 as the center.

[0085] In the example, the wheel-wing integrated assembly 7 includes: a hub drive motor stator bracket 71, a hub drive motor 72, an outer tire 73, a propulsion motor 74, and a blade 75;

[0086] The hub drive motor stator bracket 71 includes: a flange 713 and a center cylinder 712; the flange is rigidly connected to the connecting flange fixedly installed at the end of the joint tilting servo output shaft, and the center cylinder 712 is rigidly connected to the flange 713; the propulsion motor 74 is coaxially installed in the inner cavity of the center cylinder 712, the output shaft of the propulsion motor 74 extends out of the center cylinder 712 and is drivenly connected to the blade 75, and the blade 75 is located within the inner circle of the rim of the outer tire 73 when it is retracted; the stator of the hub drive motor 72 is fixed to the outer periphery of the center cylinder 712, and the outer rotor of the hub drive motor 72 is supported on the outer circular surface of the center cylinder by two sets of deep groove ball bearings, and the outer periphery of the outer rotor of the hub drive motor 72 is rigidly connected to the inner rim of the outer tire 73; two locking grooves 711 on the hub drive motor stator bracket 71 are formed on the side of the flange 713.

[0087] This invention also provides a control method for a dual-joint tandem-driven land-air dual-modal chassis system. Based on the above system, the method steps are as follows:

[0088] 1) Takeoff control from land to air;

[0089] 11) The central computing unit sends a lifting command to the joint servo motor in the composite joint drive assembly. The joint servo motor drives the suspension arm to swing downward relative to the vehicle body base, overcoming the weight of the entire vehicle and smoothly lifting the vehicle body base.

[0090] 12) The absolute encoder collects the absolute angle of the suspension arm in real time during the downward swing of the suspension arm and sends the angle data to the central computing unit. When the absolute angle reaches the target position corresponding to the set takeoff ground clearance, the central computing unit controls the joint servo motor to enter the position holding mode and uses the electromagnetic holding torque of the motor to rigidly lock the current attitude of the suspension arm.

[0091] 13) After the central computing unit confirms that the vehicle height is locked, it sends an unlocking signal to the mode switching component, controls the mechanical locking pin to be energized and performs a retraction action, so that the telescopic rod exits the locking groove, thereby releasing the physical constraint on the rotational degree of freedom of the wheel-wing integrated component;

[0092] 14) The articulated servo drive wheel-wing integrated assembly smoothly and uniformly rotates 90 degrees from a ground driving attitude perpendicular to the ground until it reaches a horizontal flight attitude parallel to the ground.

[0093] 15) The central computing unit controls the cutting off of the electromagnetic power supply to the mechanical locking pin. The mechanical locking pin is ejected by the driving force of the return spring and embedded in the locking groove corresponding to the horizontal flight attitude, realizing the mechanical rigid locking between the wheel-wing integrated component and the suspension swing arm, so as to isolate the impact and wear of the high-frequency flight vibration generated by the propeller of the flying car on the internal reduction gear of the joint rollover servo.

[0094] 2) Landing cushioning control;

[0095] 21) The multi-source sensing unit collects the real altitude and descent rate of the flying car in real time during the landing process. When the real altitude is equal to the landing value, the central computing unit sends an unlocking command signal to the mode switching component. The mechanical locking pin is released. After the pin is released, the joint flip servo drives the wheel-wing integrated component to smoothly and uniformly flip 90 degrees from the flight attitude parallel to the ground until it reaches the ready landing attitude perpendicular to the ground.

[0096] 22) When the outer tire touches the ground, the coil spring and shock absorber undergo passive compression deformation to absorb the landing impact force and complete the first stage of mechanical buffer protection. At the same time, the absolute encoder synchronously collects the angle deviation of the suspension arm caused by the compression of the elastic damping component and sends it to the central computing unit. The central computing unit controls the release of the original position holding mode of the joint servo motor, switches the joint servo motor to impedance control mode, and retrieves the impedance parameter group corresponding to the landing impact condition from the pre-calibrated parameter table.

[0097] The impedance parameter set includes virtual torsional damping. Virtual torsional stiffness and virtual moment of inertia ;

[0098] 23) Calculation of impedance torque for joint servo motors The calculation formula is as follows:

[0099] ;

[0100] in, This represents the restoring torque of the current elastic damping component; in this impedance control mode, the joint servo motor drives the suspension arm to retract upwards to execute the knee flexion action; during this stage, virtual torsional damping... Large values ​​are chosen to provide strong energy dissipation, virtual torsional stiffness A small value makes the system exhibit compliant characteristics in the impact direction, and the virtual moment of inertia The value is set too high to smooth the sudden peak of the impact acceleration; the active damping torque generated by the joint servo motor and the restoring torque of the coil spring and shock absorber form a parallel synergy in mechanical transmission, and together dissipate the inertial kinetic energy from the descent of the vehicle body base;

[0101] 24) As the landing kinetic energy gradually decays and dissipates, the central computing unit dynamically adjusts the impedance parameter set for the landing impact condition in stages based on the vehicle attitude data collected by the multi-source sensing unit. During the rebound suppression phase after the impact peak, it maintains high virtual torsional damping. To suppress the rebound force generated when the coil spring and shock absorber release their elastic potential energy after reaching their compression limit, the virtual torsional stiffness is gradually increased. The suspension arms are guided to smoothly return to the target cruise angle; parameter switching adopts first-order inertial transition to avoid step jumps in control torque; when the suspension arm angle returns to the target value corresponding to the preset ground cruise clearance, the impedance parameter group is switched to the ground driving mode parameter group, ultimately achieving a soft landing of the flying car.

[0102] It should be noted that the impedance parameter set is determined as follows:

[0103] The Beetle Antennae Search (BAS) algorithm is used to encode the 12 impedance parameters to be optimized into a 12-dimensional position vector. A comprehensive performance evaluation function J is constructed as the fitness function. The comprehensive performance evaluation function J simultaneously considers the root mean square value and peak value of the vehicle's vertical acceleration, the overshoot of the swing arm angle, and the motor energy consumption. The impact condition of the flying car landing at a set descent speed is simulated in the simulation environment. The smaller the value of the comprehensive performance evaluation function J, the better the comprehensive performance.

[0104] The search direction is determined by applying symmetrical perturbations to both sides of the current parameter vector and comparing the differences in the values ​​of the comprehensive performance evaluation function J at two points. The parameter vector is updated in the direction where the value of J is lower, and the search step size gradually decreases with the number of iterations until it converges to the optimal parameters. The above optimization process is run under different working conditions (different descent speeds, vehicle weights, etc.) to establish a mapping dataset of working conditions and optimal parameters.

[0105] The BP neural network is trained using a mapping dataset optimized by the Beetle Antennae Search (BAS) algorithm. The network's input consists of five features: descent speed, ground clearance, swing arm angle and angular velocity, and vehicle mass estimate. The output consists of 12 impedance parameters from four sets of composite joint drive components. Before training, the initial weights and thresholds of the BP neural network are pre-optimized using the Beetle Antennae Search algorithm to improve the network's convergence accuracy. The central computing unit uses the optimized BP neural network to predict the corresponding impedance parameter set based on the data collected by the multi-source sensing unit in each control cycle and calculates the control torque.

[0106] This invention has many specific applications. The above description is only a preferred embodiment of this invention. It should be noted that for those skilled in the art, several improvements can be made without departing from the principle of this invention, and these improvements should also be considered within the scope of protection of this invention.

Claims

1. A dual-joint tandem-driven land-air dual-mode chassis system, applied in flying cars, characterized in that, include: Multi-source sensing unit, central computing unit, vehicle body base, composite joint drive assembly, suspension control arm, mode switching assembly, and wheel-wing integrated assembly; The multi-source sensing unit is used to collect vehicle attitude data and ground clearance data in real time and send them to the central computing unit. The central computing unit, installed in the vehicle body base, is used to output control commands to the composite joint drive assembly and the mode switching assembly; One end of the composite joint drive assembly is fixedly connected to the vehicle body base, and the other end is rigidly connected to one end of the suspension swing arm; The other end of the suspension arm is connected to the mode switching component; The mode switching component is connected to the wheel-wing integrated component.

2. The dual-joint tandem-driven land-air dual-mode chassis system according to claim 1, characterized in that, The central computing unit performs Kalman filtering fusion on the data sent by the multi-source sensing unit, estimates the vehicle's vertical acceleration, pitch angle, roll angle and ground clearance of each wheel in real time, and makes motion mode decisions in conjunction with the target mission instructions, and outputs the corresponding joint control commands.

3. The dual-joint tandem-driven land-air dual-mode chassis system according to claim 1, characterized in that, The vehicle body base has a set of mounting positions at each of its four corners for fixing the leg brackets. One end of the leg bracket is fixedly connected to the vehicle body base, and the other end is rigidly connected to the composite joint drive assembly. Through the transfer of the leg brackets, the joint drive load is effectively distributed to the vehicle body base.

4. The dual-joint tandem-driven land-air dual-mode chassis system according to claim 3, characterized in that, The composite joint drive assembly includes a joint servo motor, an absolute encoder, and an elastic damping assembly; the joint servo motor and the elastic damping assembly are coaxially connected in parallel. The stator flange of the joint servo motor is rigidly connected to the leg support of the vehicle body base, and the output shaft of the joint servo motor is rigidly connected to one end of the suspension swing arm via a keyway, forming an active drive link from the vehicle body base to the suspension swing arm. In position servo mode, the joint servo motor drives the suspension swing arm to deflect in order to adjust the vehicle body's ground clearance and thrust direction. In impedance control mode, based on the angle and angular velocity signals fed back by the absolute encoder and the vehicle body attitude data fed back by the multi-source sensing unit, the central computing unit calculates and outputs a dynamically adjustable impedance torque in real time. The absolute encoder is coaxially integrated into the output shaft of the joint servo motor. The housing of the absolute encoder is fixedly mounted on the end cover of the joint servo motor, keeping it relatively stationary with respect to the vehicle body base. The detection shaft of the absolute encoder is coaxially fixed to the output shaft of the joint servo motor and rotates synchronously with the suspension arm. The absolute encoder collects the absolute angular position signal and instantaneous angular velocity signal of the suspension arm relative to the leg support, which are used as state feedback inputs for the stiffness and damping terms in impedance control. The central computing unit calculates the real-time deformation of the elastic damping component based on the absolute angle signal, and then obtains the restoring torque of the elastic damping component acting on the suspension arm. The elastic damping assembly includes: a shock absorber and a coil spring sleeved on the shock absorber; one end of the shock absorber is hinged to a first hinge lug on the leg support, and the other end is hinged to a second hinge lug in the middle of the suspension arm, with both hinge axes parallel to the axis of the output shaft of the joint servo motor; the coil spring is installed in a pre-compressed state between the spring seats at both ends of the shock absorber; when the suspension arm swings around the output shaft, the distance between the two hinge lugs changes with the swing angle, and the coil spring generates a restoring torque on the suspension arm around the axis of the output shaft, while the shock absorber simultaneously generates a damping torque that resists the swing of the suspension arm.

5. The dual-joint tandem-driven land-air dual-mode chassis system according to claim 4, characterized in that, The resistive torque is composed of the following three superposition components: Virtual inertial torque proportional to the angular acceleration of the suspension arm swinging about the output shaft , It is used to adjust how quickly the suspension control arm responds to changes in acceleration; Virtual damping torque proportional to the angular velocity of the suspension arm swinging about the output shaft , It is used to control the rate of dissipation of kinetic energy; Virtual stiffness moment proportional to the angular deviation of the suspension control arm , It is used to adjust the magnitude of the restoring torque after deviating from the target angle; in, The angle of rotation of the suspension arm around the output shaft, measured by an absolute encoder; This is the angular velocity at that turning angle; The angular acceleration at that angle is expressed as angular velocity. Acquisition of differential or six-axis inertial measurement data; To balance the target angle; These are virtual moment of inertia, virtual torsional damping, and virtual torsional stiffness, respectively. When there is a landing impact or road bumps, the joint servo motor actively adjusts the output torque according to the three components of the impedance torque mentioned above, adapts to the impact force to make the suspension arm deflect and yield in the direction of the impact, and uses the damping component to absorb and suppress the oscillation generated when the coil spring releases its elastic potential energy during the suspension arm reset phase.

6. The dual-joint tandem-driven land-air dual-mode chassis system according to claim 5, characterized in that, The suspension arm is made of carbon fiber composite material, with a hollow interior forming a wiring channel. One end is connected to the output shaft of the joint servo motor via a keyway, and the other end is connected to the mode switching component via a U-shaped mounting bracket.

7. The dual-joint tandem-driven land-air dual-mode chassis system according to claim 6, characterized in that, The mode switching component includes: a joint tilting servo and a mechanical locking pin; The joint-mounted tilt servo is a servo servo with an internally integrated reduction gear set, including a servo housing and an output shaft. A connecting flange is fixedly provided at the end of the output shaft. The servo housing is fixedly installed in a U-shaped mounting base. The axis of the connecting flange is perpendicular to the longitudinal centerline of the suspension arm and is located in the swing plane of the suspension arm. The connecting flange is rigidly connected to the wheel-wing integrated assembly, so that the wheel-wing integrated assembly can rotate as a whole around the output shaft axis of the joint-mounted tilt servo. When the suspension arm is in a vertical position, the tilt axis is horizontal and parallel to the longitudinal direction of the vehicle body. The wheel-wing integrated assembly can switch between a ground driving posture with the wheel surface vertical and a flight posture with the wheel surface horizontal by rotating 90°. The mechanical locking pin adopts an electromagnetic pin structure, consisting of a drive housing and a telescopic rod driven by it. The drive housing integrates an electromagnetic coil and a return spring. The root of the telescopic rod is connected to the return spring, and the middle part passes through the electromagnetic coil. The drive housing is rigidly installed on the inner wall of the U-shaped mounting base and is located diagonally above the joint tilting servo. The axis of the telescopic rod is parallel to the output shaft axis of the joint tilting servo.

8. The dual-joint tandem-driven land-air dual-mode chassis system according to claim 7, characterized in that, The wheel-wing integrated assembly includes: a hub drive motor stator bracket, a hub drive motor, an outer tire, a propulsion motor, and blades; The hub drive motor stator bracket includes: a flange and a central cylinder; the flange and the connecting flange are rigidly connected coaxially, and the central cylinder and the flange are rigidly connected coaxially; a propulsion motor is coaxially installed in the inner cavity of the central cylinder, the output shaft of the propulsion motor extends out of the central cylinder and is driven and connected to the blades, and the blades are located within the inner circle of the outer tire rim when retracted; the stator of the hub drive motor is fixed to the outer circumference of the central cylinder, and the outer rotor of the hub drive motor is supported on the outer circular surface of the central cylinder by two sets of deep groove ball bearings, and the outer periphery of the outer rotor is rigidly connected to the inner rim of the outer tire; two locking grooves on the hub drive motor stator bracket are formed on the side of the flange.

9. A control method for a dual-joint tandem-driven land-air dual-mode chassis system, based on the system described in any one of claims 1-8, characterized in that, The steps are as follows: 1) Takeoff control from land to air; 11) The central computing unit sends a lifting command to the joint servo motor in the composite joint drive assembly. The joint servo motor drives the suspension arm to swing downward relative to the vehicle body base, overcoming the weight of the entire vehicle and smoothly lifting the vehicle body base. 12) The absolute angle of the suspension arm is collected in real time during the downward swing of the suspension arm, and the angle data is sent to the central computing unit. When the absolute angle reaches the target position corresponding to the set takeoff ground clearance, the central computing unit controls the joint servo motor in the composite joint drive assembly to enter the position holding mode and uses the electromagnetic holding torque of the motor to rigidly lock the current attitude of the suspension arm. 13) After the central computing unit confirms that the vehicle height is locked, it sends an unlocking signal to the mode switching component, controls the mechanical locking pin in the mode switching component to be energized and perform a retraction action, so that the telescopic rod in the mechanical locking pin is removed from the locking groove, thereby releasing the physical constraint on the rotational degree of freedom of the wheel-wing integrated component; 14) The mode switching component drives the wheel-wing integrated component to smoothly and uniformly rotate 90 degrees from a ground driving attitude perpendicular to the ground until it reaches a horizontal flight attitude parallel to the ground. 15) The central computing unit controls the cutting off of the electromagnetic power supply to the mechanical locking pin. The mechanical locking pin is ejected by the driving force of the return spring and embedded in the locking groove corresponding to the horizontal flight attitude, realizing the mechanical rigid locking between the wheel-wing integrated component and the suspension swing arm. 2) Landing cushioning control; 21) Real-time acquisition of the actual altitude and descent rate of the flying car during the landing process. When the actual altitude is equal to the landing value, the central computing unit sends an unlocking command signal to the mode switching component. The mechanical locking pin is released, and the mode switching component drives the wheel-wing integrated component to smoothly and uniformly rotate 90 degrees from a flight attitude parallel to the ground until it reaches the ready landing attitude perpendicular to the ground. 22) When the outer tire of the wheel-wing integrated assembly touches the ground, the coil spring and shock absorber in the composite joint drive assembly undergo passive compression deformation to absorb the landing impact force and complete the first stage of mechanical buffer protection. At the same time, the absolute encoder in the composite joint drive assembly synchronously collects the angle deviation of the suspension arm caused by the compression of the elastic damping component and sends it to the central computing unit. The central computing unit controls the release of the original position holding mode of the joint servo motor, switches the joint servo motor to impedance control mode, and retrieves the impedance parameter set corresponding to the landing impact condition from the pre-calibrated parameter table. 23) Calculate the desired impedance torque of the joint servo motor; the active damping torque generated by the joint servo motor and the restoring torque of the coil spring and shock absorber form a parallel synergy in mechanical transmission, jointly dissipating the inertial kinetic energy from the descent of the vehicle body base; 24) The central computing unit dynamically adjusts the impedance parameter set for the landing impact condition in stages based on the vehicle attitude data collected by the multi-source sensing unit. During the rebound suppression phase after the impact peak, it maintains high virtual torsional damping. To suppress the rebound force generated when the coil spring and shock absorber release their elastic potential energy after reaching their compression limit, the virtual torsional stiffness is gradually increased. The suspension arms are guided to smoothly return to the target cruise angle; parameter switching adopts first-order inertial transition to avoid step jumps in control torque; when the suspension arm angle returns to the target value corresponding to the preset ground cruise clearance, the impedance parameter group is switched to the ground driving mode parameter group, ultimately achieving a soft landing of the flying car.

10. The control method according to claim 9, characterized in that, The impedance parameter set is determined as follows: A beetle-like biomimetic optimization algorithm is used to encode the 12 impedance parameters to be optimized into a 12-dimensional position vector. A comprehensive performance evaluation function J is constructed as the fitness function. The comprehensive performance evaluation function J simultaneously considers the root mean square value and peak value of the vehicle's vertical acceleration, the overshoot of the swing arm angle, and the motor energy consumption. The impact condition of the flying car landing at a set descent speed is simulated in the simulation environment. The smaller the value of the comprehensive performance evaluation function J, the better the comprehensive performance. The search direction is determined by applying symmetrical perturbations to both sides of the current parameter vector and comparing the differences in the values ​​of the comprehensive performance evaluation function J at two points. The parameter vector is updated in the direction where the value of J is lower, and the search step size gradually decreases with the number of iterations until it converges to a better parameter. By running the above optimization process under different operating conditions, a mapping dataset of operating conditions and optimal parameters is established.

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