A land-air robot with high ground self-adaptability and a control method thereof

Abstract

The application relates to the technical field of cross-domain multi-modal robots, in particular to a land-air robot with high ground self-adaptability and a control method thereof. The land-air robot comprises an air movement unit, a ground movement unit and an automatic driving module. The air movement unit is used for providing flight power for the land-air robot, so that the land-air robot has a flight mode. The ground movement unit is arranged at the bottom of the air movement unit, so that the land-air robot has a ground movement mode. The ground movement unit comprises a movement module and a five-link wheel-foot mechanism symmetrically arranged on the left and right sides of the land-air robot. The movement module is used for adjusting the posture of the five-link wheel-foot mechanism, so that the land-air robot realizes dynamic balance and posture righting in the ground movement mode. The automatic driving module is electrically connected with the air movement unit and the ground movement unit. The land-air robot in the application can move on land and in the air, and has good trajectory tracking performance in the land-air dual mode.

Description

Technical Field

[0001] This invention relates to the field of cross-domain multimodal robot technology, and in particular to a land-air robot with high ground adaptability and its control method. Background Technology

[0002] In recent years, unmanned aerial vehicles (UAVs) have received widespread attention and application in fields such as surveillance, search and rescue, and environmental monitoring due to their high maneuverability and hovering capabilities. Despite their significant advantages in these areas, UAVs still face challenges such as low power efficiency and small payload capacity. In contrast, unmanned ground vehicles (UGVs) do not need to constantly overcome gravity, relying directly on friction for propulsion, thus achieving higher energy efficiency and a larger payload capacity. However, the poor adaptability of traditional UGVs in unstructured terrain such as rough ground and areas with dense obstacles limits their practical application. Therefore, multimodal land-air robots have emerged, combining the flexible aerial maneuverability of UAVs with the superior energy efficiency of UGVs, significantly improving mobility and environmental adaptability.

[0003] Existing land-air multimodal robot mechanisms mainly fall into two categories: additive design and adaptive design, such as Skywalker from Zhejiang University and LEONARDO from Caltech. The former achieves land-air multimodal motion by adding omnidirectional wheels to the bottom of a quadcopter drone, but this structure cannot adapt to uneven terrain, limiting its movement scenarios. The latter achieves adaptive motion in complex terrain by adding mechanical legs to the bottom of the drone, but its movement speed is limited. Furthermore, current land-air multimodal robot control mainly includes independent multimodal control and unified multimodal control, such as Doublebee from Nanyang Technological University in Singapore and TABV from Zhejiang University. The former designs separate controllers for land and air multimodal modes, which can maximize the performance of a single mode. However, it suffers from poor mode switching coordination and high switching latency. The latter proposes a normalized model that can achieve unified multimodal control, showing stronger mode switching continuity. However, their methods are limited to specific structural configurations and exhibit insufficient versatility across different dynamic systems.

[0004] In summary, while current land and air multimodal robots possess excellent multimodal motion performance and outstanding energy efficiency, they also suffer from numerous shortcomings, including complex structures, poor terrain adaptability, and low controller precision, which significantly limit their practical applications. Summary of the Invention

[0005] This invention provides a land-air robot with high ground adaptability and its control method to solve the technical problems mentioned in the background art.

[0006] To achieve the above objectives, the technical solution of the present invention is implemented as follows:

[0007] This invention provides a land-air robot with high ground adaptability, comprising:

[0008] An air motion unit is used to provide flight propulsion for land-air robots, enabling them to have a flight mode.

[0009] The ground motion unit is located at the bottom of the air motion unit to enable the land-air robot to have a ground motion mode. The ground motion unit includes a motion module and a five-bar linkage wheel-foot mechanism symmetrically installed on the left and right sides of the land-air robot. The motion module is used to adjust the attitude of the five-bar linkage wheel-foot mechanism so that the land-air robot can achieve dynamic balance and attitude correction when in ground motion mode.

[0010] The autonomous driving module is installed above the air motion unit and is electrically connected to both the air motion unit and the ground motion unit, enabling the land-air robot to switch cyclically between flight mode and ground motion mode.

[0011] In another aspect, the present invention provides a control method for a land-air robot with high ground adaptability, used to control the land-air robot, specifically including the following steps:

[0012] S1. Based on the structure of the land-air robot, establish an inertial coordinate system and a body coordinate system. Under the inertial coordinate system and the body coordinate system, use the Newton-Euler equations to establish the first dynamic model of the land-air robot in flight mode.

[0013] S2. In the inertial coordinate system and the body coordinate system, a nonlinear dynamic model of the land-air robot in the ground motion mode is established based on the state vector and control vector of the land-air robot, and the nonlinear dynamic model is linearized to obtain the second dynamic model of the land-air robot in the ground motion mode.

[0014] S3. In the inertial coordinate system and the body coordinate system, the motion process of the land-air robot in the ground motion mode is simplified according to the assumptions, so as to obtain the first kinematic model; the assumption is that the five-bar linkage wheel-foot mechanism has no displacement in the front-back direction in the ground motion mode;

[0015] S4. Establish a five-bar coordinate system based on the five-bar wheel-foot mechanism, and use plane geometry to establish a five-bar kinematic model of the land-air robot in the ground motion mode in the five-bar coordinate system;

[0016] S5. Design a trajectory tracking controller in flight mode based on the first dynamic model, and drive the land and air robot to move in flight mode with the help of the trajectory tracking controller in flight mode;

[0017] S6. Design a robust balance controller for the land-air robot in ground motion mode based on the linearized second dynamic model. Use the robust balance controller to self-balance the land-air robot so that it can maintain balance in ground motion mode.

[0018] S7. Based on the five-bar kinematics model, design the steering controller and leg length controller for the land-air robot in the ground motion mode, and use the steering controller and leg length controller to control the steering and leg height of the land-air robot.

[0019] S8. Design a trajectory tracking controller for ground motion mode based on the first kinematic model, and drive the land-air robot to move in ground motion mode with the help of the trajectory tracking controller for ground motion mode.

[0020] The beneficial effects of this invention are:

[0021] 1. This invention discloses a land-air robot with high ground adaptability, which has two movement modes: flight mode and ground movement mode. The two modes can be switched cyclically through an autopilot module. The switching latency is low and the switching coordination is good. Moreover, the land-air robot of this invention has a simple structure, has uprighting and self-balancing functions, high control precision, and can be applied to a variety of different terrains.

[0022] 2. This invention also discloses a control method for a land-air robot. This method designs a trajectory tracking controller suitable for both flight mode and ground motion mode. Considering the robust balance requirements of the ground motion mode, the trajectory tracking controller for flight mode is constrained to obtain a trajectory tracking controller for ground motion mode. This is more convenient than designing two control algorithms independently. In addition, the trajectory tracking controller in this method has low complexity and its parameters are easy to adjust. Trajectory tracking in both flight mode and ground motion mode can be achieved by using the same set of parameters. This not only simplifies the system design and debugging process, but also results in faster convergence of trajectory tracking errors.

[0023] This method significantly improves ground adaptation performance and motion speed in ground motion mode, and has good trajectory tracking performance in both land and air modes. Attached Figure Description

[0024] Figure 1 A 3D structural diagram of a land-and-air robot;

[0025] Figure 2 This is a structural block diagram of the autonomous driving module;

[0026] Figure 3 A flowchart illustrating the control method for land and air robots;

[0027] Figure 4This is a control principle diagram for a land-air robot.

[0028] Figure 5 This is a schematic diagram of the coordinate system distribution of the five links in a five-bar linkage mechanism.

[0029] Explanation of reference numerals in the attached figures:

[0030] 10. Air motion unit; 11. Support arm; 12. High-speed brushless DC motor; 13. Electronic speed controller; 14. Propeller;

[0031] 20. Ground motion unit; 21. Five-bar linkage wheel-foot mechanism; 211. Thigh bar; 212. Front lower leg bar; 213. Rear lower leg bar; 214. Drive wheel; 22. Joint motor; 23. Auxiliary wheel;

[0032] 30. Autopilot module; 31. Onboard computer; 32. Flight controller; 33. Data transmission radio; 34. Remote control receiver; 35. Power supply. Detailed Implementation

[0033] To facilitate understanding of the present invention, a more complete description will be given below with reference to the accompanying drawings. Preferred embodiments of the invention are shown in the drawings. However, the invention can be implemented in many other different forms and is not limited to the embodiments described herein. Rather, these embodiments are provided to provide a thorough and complete understanding of the disclosure of the invention.

[0034] It should be noted that when a component is referred to as being "fixed to" or "set on" another component, it can be directly on or indirectly on that other component. When a component is referred to as being "connected to" another component, it can be directly connected to or indirectly connected to that other component.

[0035] It should be understood that the terms "length", "width", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on the present invention.

[0036] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of this invention, "a plurality of" means two or more, unless otherwise explicitly specified.

[0037] Reference Figure 1 This application provides a land-air robot with high ground adaptability, comprising:

[0038] The air motion unit 10 is used to provide flight power for the land-air robot, so that the land-air robot has a flight mode;

[0039] The ground motion unit 20 is located at the bottom of the air motion unit 10 to enable the land-air robot to have a ground motion mode. The ground motion unit 20 includes a motion module and a five-bar linkage wheel-foot mechanism 21 symmetrically installed on the left and right sides of the land-air robot. The motion module is used to adjust the attitude of the five-bar linkage wheel-foot mechanism 21 so that the land-air robot can achieve dynamic balance and posture correction in the ground motion mode. At the same time, the motion module is also used to drive the land-air robot to run in the ground motion mode.

[0040] The autonomous driving module 30 is installed above the air motion unit 10 and is electrically connected to the air motion unit 10 and the ground motion unit 20 respectively, so that the land-air robot can switch cyclically between flight mode and ground motion mode.

[0041] In some embodiments, refer to Figure 1 The aerodynamic unit 10 includes a quadcopter frame and a power kit;

[0042] The quadcopter frame includes four X-shaped support arms 11, each of which has an identical left forearm, right forearm, left rear arm, and right rear arm. The left forearm and right rear arm are located on the same diagonal line, and the right forearm and left rear arm are located on the same diagonal line.

[0043] The power kit includes four high-speed brushless DC motors 12, an electronic speed controller 13, a power distribution board, and four propellers 14. The four high-speed brushless DC motors 12 are respectively mounted on the left forearm, right forearm, left rear arm, and right rear arm, and the four propellers 14 are respectively mounted on the output shafts of the four high-speed brushless DC motors 12. The power supply 35 on the automatic driving module 30 is electrically connected to the power distribution board, the electronic speed controller 13, and the four high-speed brushless DC motors 12 to realize the power supply and speed regulation of the four high-speed brushless DC motors 12.

[0044] In some embodiments, refer to Figure 1 The motion module includes four joint motors 22, two drive motors, two drive wheels 214, and four auxiliary wheels 23; the four joint motors 22 are evenly distributed on the left and right sides of the land and air robot, and the two joint motors 22 on the same side are distributed along the front and rear direction; the two drive wheels 214 are respectively mounted on the two drive motors.

[0045] The five-bar linkage mechanism 21 includes two thigh rods 211, a front lower leg rod 212, a rear lower leg rod 213, and two drive wheels 214. One side of each of the two thigh rods 211 is fixed to the output shaft of two joint motors 22 on the same side, and the other side is rotatably connected to one side of the front lower leg rod 212 and the rear lower leg rod 213, respectively. The other side of each of the front lower leg rod 212 and the rear lower leg rod 213 is connected to one of the drive motors. The two drive wheels 214 are respectively arranged between one of the thigh rods 211 and the front lower leg rod 212, and between the other thigh rod 211 and the rear lower leg rod 213.

[0046] In some embodiments, refer to Figure 2 The autonomous driving module 30 includes:

[0047] An onboard computer 31 is used to run programs and make action decisions for the land and air robots; the programs include balance algorithms, etc.

[0048] Flight controller 32, electrically connected to onboard computer 31, is used to control aerodynamic unit 10;

[0049] The data transmission radio 33 is electrically connected to the onboard computer 31 and is used to wirelessly transmit the operational status information of the land-air robot to an external ground control station.

[0050] The remote control receiver 34 is electrically connected to the onboard computer 31 and is used to receive control commands issued by the operator's handheld remote control and transmit them to the onboard computer 31.

[0051] Power supply 35, installed above ground motion unit 20, is used to power the entire land-air robot.

[0052] The specific process of switching between flight mode and ground movement mode in the land-air robot of this invention is as follows:

[0053] The steps for a land-to-air robot to switch from flight mode to ground movement mode include the following:

[0054] (a) The land-air robot flies to the designated location and begins hovering flight.

[0055] (b) The land-air robot descends slowly until the ground motion unit 20 touches the ground. At this point, the ground motion unit 20 is enabled, and the air motion unit 10 is disabled. The drive motor and joint motor 22 in the ground motion unit 20 provide balancing forces for the land-air robot. Thus, the land-air robot switches from flight mode to ground motion mode.

[0056] Switching from ground motion mode to flight mode involves the following steps:

[0057] (a) The land-air robot moves to the designated position, the aerial motion unit 10 is enabled, the high-speed brushless DC motor 12 starts working and provides lift for the land-air robot, and the land-air robot begins to rise gradually.

[0058] (b) When the land-air robot leaves the ground, the ground motion unit 20 is disabled, keeping the five-link wheel-foot structure 21 stationary. At this time, the high-speed brushless DC motor 12 on the air motion unit 10 continues to provide the land-air robot with aerial maneuverability. Thus, the land-air robot switches from ground motion mode to flight mode.

[0059] All of the above switching processes are completed under the control of the autonomous driving module 30.

[0060] The land-air robot of this invention has two movement modes: flight mode and ground movement mode. The two modes can be switched cyclically through an autopilot module. The switching latency is low and the switching coordination is good. In addition, the land-air robot of this invention has a simple structure, has uprighting and self-balancing functions, and has high control precision, making it suitable for a variety of different terrains.

[0061] Reference Figure 3 and Figure 4 In another aspect, the present invention provides a control method for a land-air robot with high ground adaptability, characterized in that it is used to control the land-air robot and specifically includes the following steps:

[0062] S1. Based on the structure of the land-air robot, establish an inertial coordinate system and a body coordinate system. The origin of the inertial coordinate system is a self-defined point, the x-axis of the inertial coordinate system points eastward, the y-axis points northward, and the z-axis is vertical. The origin of the body coordinate system is the center of the land-air robot, the x-axis of the body coordinate system points directly in front of the land-air robot, the y-axis points to the left side of the land-air robot, and the z-axis is vertical.

[0063] In the inertial coordinate system and the body coordinate system, the first dynamic model of the land-air robot in flight mode is established using the Newton-Euler equations and based on the rotational inertia matrix, the total thrust of the land-air robot, air resistance, and the flight characteristics of the land-air robot in flight mode; the first dynamic model includes the position loop dynamic model and the attitude loop dynamic model.

[0064] S2. In the inertial coordinate system and the body coordinate system, based on the state vector and control vector of the land-air robot and using the Newton-Euler equation, a nonlinear dynamic model of the land-air robot in the ground motion mode is established, and the nonlinear dynamic model is linearized to obtain the second dynamic model of the land-air robot in the ground motion mode.

[0065] S3. In the inertial coordinate system and the body coordinate system, the motion process of the land-air robot in the ground motion mode is simplified according to the assumptions, so as to obtain the first kinematic model; the assumption is that the five-bar linkage wheel-foot mechanism 21 has no displacement in the front-back direction or the displacement is extremely small in the ground motion mode.

[0066] S4. Establish a five-bar coordinate system based on the five-bar linkage mechanism 21. The origin of the five-bar coordinate system is in the middle of one of the joint motors 22. The five-bar coordinate system is a two-dimensional plane coordinate system, in which the x-axis of the five-bar coordinate system is the horizontal direction and the y-axis is the numerical direction.

[0067] A five-bar kinematic model of the ground motion mode of the land-air robot is established in a five-bar coordinate system using planar geometry methods.

[0068] S5. Based on the first dynamic model, design the trajectory tracking controller for the land-air robot in flight mode. Input the preset desired flight trajectory into the trajectory tracking controller in flight mode to obtain the desired thrust and desired torque in flight mode. Drive the land-air robot to move in flight mode according to the desired thrust and desired torque in flight mode.

[0069] S6. Design a robust balance controller for the land-air robot in ground motion mode based on the linearized second dynamic model. Input the preset ground motion state into the robust balance controller to obtain the expected joint torque and driving torque in the ground motion mode. Drive the land-air robot according to the expected joint torque and expected driving torque in the ground motion mode so that the land-air robot maintains balance in the ground motion mode.

[0070] S7. Based on the five-bar kinematic model and PID controller principle, design the steering controller and leg length controller for the land-air robot in ground motion mode. Input the preset ground motion angular velocity and ground motion leg length into the steering controller and leg length controller in ground motion mode to obtain the sum of the driving torque difference of the two drive wheels 214 and the torque provided by the joint torque in ground motion mode. Drive the land-air robot according to the expected driving torque difference of the two wheels and the sum of the joint torque in ground motion mode to achieve steering and leg height control.

[0071] S8. Based on the first kinematic model, design a trajectory tracking controller for the land-air robot in ground motion mode. Input the preset desired ground motion trajectory into the trajectory tracking controller in ground motion mode to obtain the desired velocity and desired angular velocity in ground motion mode. Input the desired velocity and desired angular velocity in ground motion mode into the steering controller to drive the land-air robot to move in ground motion mode.

[0072] In some embodiments, the first dynamic model in S1 is specifically as follows:

[0073]

[0074] In the formula, B represents the body coordinate system, I represents the inertial coordinate system, and v I =[v x v y v z ] T R represents the velocity vector in the inertial coordinate system during flight mode, R represents the rotation matrix from the inertial coordinate system to the body coordinate system during flight mode, and ω represents the velocity vector in the inertial coordinate system during flight mode. B The angular velocity in flight mode is represented by g in the body coordinate system, g represents gravitational acceleration, m represents the total mass of the land-air robot, and J represents the moment of inertia matrix. -1 F represents the inverse of the moment of inertia matrix. t F represents the total thrust generated by the propellers of the land-air robot in the body coordinate system. d Let e3 represent the air resistance experienced by the land-air robot in the inertial coordinate system, where e3 = [0 0 1]. T Let T denote the third reference vector, and τ denote the transpose. B This represents the total torque generated by the propeller in the body coordinate system, and the dot symbol represents the first derivative.

[0075] In some embodiments, S2 specifically includes the following steps:

[0076] S21. In the inertial coordinate system and the body coordinate system, based on the state vector and control vector of the land-air robot, and using the Newton-Euler equations, establish the second dynamic model of the land-air robot in the ground motion mode;

[0077] S22. For the second dynamic model of the land-air robot in the ground motion mode, Taylor expansion is used to ignore higher-order terms to obtain the linearized second dynamic model of the land-air robot in the ground motion mode. The higher-order terms refer to the terms with an index of 3 or higher in the initially obtained second dynamic model.

[0078] In some embodiments, the linearized nonlinear dynamic model and the linearized second dynamic model in S2 are derived as follows:

[0079]

[0080] In the formula, f2 represents the nonlinear dynamic model of the ground motion mode of the land-air robot: The state vector is θ and φ, which are the vertical deflection angle of the pendulum and the horizontal tilt angle of the land-air robot, respectively. The pendulum is the line connecting the center point of the drive wheel 214 and the midpoint of the line connecting the two joint motors 22 on the same side. and These represent the angular velocities of the pendulum about the center of the drive wheel 214 and the angular velocities of the land-air robot about the center of the hip joint, respectively. The center of the hip joint is the midpoint of the line connecting the two joint motors 22. B and Represent the displacement and velocity in the mechanical system, respectively; u G =[T w T p ] T For the control vector, T w The torque of drive wheel 214 is in the same direction as the vertical deflection angle θ of the rocker arm, T p The torque of the joint motor 22, y G The system output of the land and air robot is represented by: A G B represents the state matrix; G Denotes the control matrix; and the state matrix A G and control matrix B G The specific calculation formula is as follows:

[0081]

[0082] in, These are the equilibrium points of the state vectors and control vectors of the land and air robots, respectively. This indicates the partial derivative sign.

[0083] In some embodiments, the first kinematic model in S3 is specifically as follows:

[0084]

[0085] In the formula, x D =[x W y W ψ] T u D =[v in w in ] T Let x represent the state vector and control input vector of the land-air robot in its ground operation mode, respectively. W y W ψ and v represent the displacement components and yaw angle of the robot in the x and y directions, respectively, in the world coordinate system. in w in These represent the desired velocity and angular velocity, respectively.

[0086] In some embodiments, the five-bar kinematic model in S4 is specifically as follows:

[0087] x F-L =f3(q)

[0088] In the formula, f3 represents the five-bar kinematic model; the pendulum state vector x F-L=[L0, φ0] T The angle vector q = [φ1, φ4] T φ1 and φ4 represent the angles between the lines containing the length L1 of the first thigh rod 211 and the length L4 of the second thigh rod 211 on the same side and the positive x-axis, respectively. The length L1 of the first thigh rod 211 is the line connecting the first joint motor 22 where the first thigh rod 211 is located and the nearest auxiliary wheel 23. The length L4 of the second thigh rod 211 is the line connecting the second joint motor 22 connected to the second thigh rod 211 and the second auxiliary wheel 23. L0 represents the length of the swing arm on the land-air robot, or the leg height, and φ0 represents the angle between the line containing the leg height L0 and the positive x-axis.

[0089] In some embodiments, S5 specifically includes the following steps:

[0090] S51, Preset land and air robots in inertial coordinate system T s The desired position and desired velocity of the land-air robot T are obtained iteratively using a model prediction method based on the flight mode. s The actual position and speed in real-time flight mode are based on the land-air robot's position in T. s The state error e between the expected state and the actual state in real-time flight mode Q (T s Based on the state error e between the expected state and the actual state of the land-air robot in flight mode at time t, Q (t);

[0091] Among them, T s The state error e at time t Q (T s The specific formula for calculating ) is as follows:

[0092]

[0093] The state error e at time t Q The specific formula for calculating (t) is as follows:

[0094]

[0095] S52. Based on the first dynamic model and the principle of the model predictive controller, in the 0-T... s Minimize the state error e within the time period Q (T s ), control input State error e Q (t), construct the first optimal control problem of the land-air robot in flight mode, and construct the first constraint term in combination with the actual application scenario. Combine the first optimal control problem and the first constraint term to construct the trajectory tracking controller of the land-air robot in flight mode.

[0096] The optimal control problem is as follows:

[0097]

[0098] The first constraint term is as follows:

[0099] φ min ≤φ in ≤φ max

[0100] θ min ≤θ in ≤θ max T min ≤T s ≤T max ;

[0101] S53. Input the preset desired flight trajectory into the trajectory tracking controller in flight mode to obtain the desired thrust and desired torque in flight mode, and drive the land-air robot to move in flight mode according to the desired thrust and desired torque in flight mode.

[0102] In some embodiments, the trajectory tracking controller in flight mode S5 is specifically as follows:

[0103]

[0104] φ min ≤φ in ≤φ max

[0105] θ min ≤θ in ≤θ max T min ≤T s ≤T max

[0106] in, and Let these represent the state vector and control input vector of the land-air robot in flight mode, respectively. and Representing the three-dimensional position, velocity, and Euler angles respectively. Denotes the set of real numbers, φ in θ in and f in Let f1(·) represent the desired pitch angle control input, the desired roll angle control input, and the desired thrust input, respectively. Let f1(·) represent the first dynamic model in S1. Represents 0 to T sThe optimal control input at any given time. and Let t and T represent time respectively. s The expected state vector at time φ max θ max T max , φ min ,θ min ,T min These represent the control input vector u. Q The upper and lower bounds are given by M, N, and H, which represent the state, input, and final state weighting matrices, respectively, and st indicates the constraint. The formal specifications all represent the weighted Euclidean inner product, for example:

[0107] The last two lines of the formula for the trajectory tracking controller in flight mode are the first constraint terms.

[0108] In some embodiments, S6 specifically includes the following steps:

[0109] S61. Preset the desired leg posture, desired body posture, desired displacement, and desired velocity of the land-air robot in the ground motion mode in the inertial coordinate system. Obtain the actual leg posture, actual body posture, actual displacement, and actual velocity of the land-air robot in the ground motion mode. Based on the leg posture tracking error e between the desired leg posture and the actual leg posture of the land-air robot in the ground motion mode. θ and its derivative Based on the body attitude tracking error e between the expected and actual body attitudes of the land-air robot in ground motion mode. φ and its derivative Based on the displacement tracking error e between the expected displacement and the actual displacement of the land-air robot in ground motion mode. x Based on the speed tracking error e between the expected speed and the actual speed of the land-air robot in ground motion mode. v Using leg pose tracking error e θ and its derivative Aircraft attitude tracking error e φ and its derivative Displacement tracking error e x and speed tracking error e v The comprehensive error E between the constructed state vector and the desired state vector is calculated using the following formula:

[0110]

[0111] S62. Solve for the positive definite matrix P based on the continuous-time algebraic Riccati equation. The positive definite matrix P is the solution to the continuous-time algebraic Riccati equation.

[0112] S63. Construct the objective function based on the principle of linear quadratic regulators, as follows:

[0113]

[0114] S64. Solve for the feedback matrix K based on the objective function and the positive definite matrix P;

[0115] S65. Based on the linearized second dynamic model, the principle of linear quadratic regulator, the comprehensive error E, and the feedback matrix K, design a robust balance controller for the land-air robot in the ground motion mode.

[0116] S66. Input the preset ground motion state into the robust balance controller to obtain the expected joint torque and driving torque in the ground motion mode. Drive the land-air robot according to the expected joint torque and expected driving torque in the ground motion mode so that the land-air robot maintains balance in the ground motion mode.

[0117] In some embodiments, the robust balance controller in S6 is specifically as follows:

[0118]

[0119] In the formula, Let x be the desired state vector of the land-air robot in its ground motion mode, where x ref and Let K represent the desired position and desired velocity, respectively, and K be the feedback matrix. The formula for calculating the feedback matrix K is as follows:

[0120]

[0121] Where, R∈R 2 Let be a symmetric positive definite matrix representing the cost associated with the state vector; let be a positive definite matrix representing the solution to the continuous-time algebraic Ricati equation; and let the positive definite matrix P be solvable by the following formula:

[0122]

[0123] In some embodiments, S7 specifically includes the following steps:

[0124] S71. Based on the expected leg length L of the land-air robot in its ground movement mode. d The leg length tracking error e in ground motion mode is obtained by comparing the actual leg length L0 with the actual leg length. L According to the leg length tracking error e in the ground motion mode L Design of a leg length controller for a land-air robot in ground motion mode based on PID controller principle;

[0125] S72, Based on the desired rotational speed ω of the land-air robot in its ground motion mode. d The speed tracking error e in ground motion mode is obtained by combining the actual speed ω0. ω Based on the rotational speed tracking error e in ground motion mode ω Design of a steering controller for a land-air robot in ground motion mode based on PID controller principle;

[0126] S73. Input the preset ground motion angular velocity and ground motion leg length into the steering controller and leg length controller in the ground motion mode to obtain the sum of the driving torque difference of the two drive wheels 214 and the torque provided by the joint torque in the ground motion mode. Drive the land-air robot according to the expected sum of the driving torque difference of the two wheels and the joint torque in the ground motion mode to achieve steering and leg height control.

[0127] In some embodiments, S8 specifically includes the following steps:

[0128] S81. Preset the desired angle and desired displacement of the land-air robot in the ground motion mode in the inertial coordinate system, obtain the actual angle and actual displacement of the land-air robot in the ground motion mode, and based on the land-air robot in T... s The state error e between the desired state and the actual state in the ground motion mode at time step D (T s Based on the state error e between the expected state and the actual state of the land-air robot in the ground motion mode at time t, D (t);

[0129] Wherein, the state error e D (T s The specific formula for calculating ) is as follows:

[0130]

[0131] State error e D The specific formula for calculating (t) is as follows:

[0132]

[0133] S82, Based on the first kinematic model and the principle of the model predictive controller, in the 0-T... s Within the time period, by minimizing the state error e D (T s ), control input and state error e D (t), construct the second optimal control problem of the land-air robot in the ground motion mode, and construct the second constraint term in combination with the actual application scenario. Combine the second constraint term and the second optimal control problem to construct the trajectory tracking controller of the land-air robot in the ground motion mode.

[0134] The second optimal control problem is as follows:

[0135]

[0136] The second constraint is as follows:

[0137]

[0138] 0≤v in ≤v max ω min ≤ω in ≤ω max ;

[0139] S83. Input the preset ground motion desired trajectory into the trajectory tracking controller in the ground motion mode to obtain the desired velocity and desired angular velocity in the ground motion mode. Input the desired velocity and desired angular velocity in the ground motion mode into the steering controller to drive the land-air robot to move in the ground motion mode.

[0140] In some embodiments, the trajectory tracking controller in the human ground motion mode of S8 is expressed by a formula, as follows:

[0141]

[0142] 0≤v in ≤v max ω min ≤ω in ≤ω max

[0143] In the formula, Represents 0 to T s The optimal control input at any given time. and Let t and T represent times respectively. s The expected state at time v max v in ω max ω min Indicate u D The upper and lower limits are defined by U, W, and S, which represent the weighted matrices of the state, input, and final state, respectively. The last two lines of the trajectory tracking control expression are the second constraint terms.

[0144] This invention discloses a control method for a land-air robot. The method designs a trajectory tracking controller suitable for both flight and ground motion modes. Considering the robust balance requirements of the ground motion mode, the trajectory tracking controller for flight mode is constrained to obtain a trajectory tracking controller for ground motion mode. This is more convenient than designing two separate control algorithms. In addition, the trajectory tracking controller in this method has low complexity and its parameters are easy to adjust. Trajectory tracking in both flight and ground motion modes can be achieved using the same set of parameters. This not only simplifies the system design and debugging process but also results in faster convergence of trajectory tracking errors.

[0145] Furthermore, this method significantly improves ground adaptation performance and motion speed in ground motion mode, and has good trajectory tracking performance in both land and air modes.

[0146] The above description is merely a specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in the present invention should be included within the scope of protection of the present invention. Furthermore, the technical solutions of the various embodiments of the present invention can be combined with each other, but this must be based on the ability of those skilled in the art to implement them. When the combination of technical solutions is contradictory or cannot be implemented, it should be considered that such a combination of technical solutions does not exist and is not within the scope of protection claimed by the present invention. Therefore, the scope of protection of the present invention should be determined by the scope of the claims.

Claims

1. A control method for a land-air robot with high ground adaptability, characterized in that, Land and air robots include: An air motion unit (10) is used to provide flight power for the land-air robot so that the land-air robot has a flight mode; The ground motion unit (20) is located at the bottom of the air motion unit (10) to enable the land-air robot to have a ground motion mode. The ground motion unit (20) includes a motion module and a five-bar linkage wheel-foot mechanism (21) symmetrically installed on the left and right sides of the land-air robot. The motion module is used to adjust the attitude of the five-bar linkage wheel-foot mechanism (21) so that the land-air robot can achieve dynamic balance and attitude correction in the ground motion mode. An autonomous driving module (30) is installed above the air motion unit (10) and electrically connected to the air motion unit (10) and the ground motion unit (20) respectively, so that the land-air robot can switch cyclically between flight mode and ground motion mode; The control method for land-and-air robots specifically includes the following steps: S1. Based on the structure of the land-air robot, establish an inertial coordinate system and a body coordinate system. Under the inertial coordinate system and the body coordinate system, use the Newton-Euler equations to establish the first dynamic model of the land-air robot in flight mode. S2. In the inertial coordinate system and the body coordinate system, a nonlinear dynamic model of the land-air robot in the ground motion mode is established based on the state vector and control vector of the land-air robot, and the nonlinear dynamic model is linearized to obtain the second dynamic model of the land-air robot in the ground motion mode. S3. In the inertial coordinate system and the body coordinate system, the motion process of the land-air robot in the ground motion mode is simplified according to the assumptions, so as to obtain the first kinematic model; the assumption is that the five-bar linkage wheel-foot mechanism (21) in the ground motion mode has no displacement in the front and rear directions; S4. Based on the five-bar linkage wheel-foot mechanism (21), establish a five-bar coordinate system, and use the planar geometry method to establish a five-bar kinematic model of the ground motion mode of the land-air robot in the five-bar coordinate system; S5. Design a trajectory tracking controller in flight mode based on the first dynamic model, and drive the land and air robot to move in flight mode with the help of the trajectory tracking controller in flight mode; S6. Design a robust balance controller for the land-air robot in ground motion mode based on the linearized second dynamic model. Use the robust balance controller to self-balance the land-air robot so that it can maintain balance in ground motion mode. S7. Based on the five-bar kinematic model, design the steering controller and leg length controller for the land-air robot in the ground motion mode, and use the steering controller and leg length controller to control the steering and leg height of the land-air robot. S8. Design a trajectory tracking controller in the ground motion mode based on the first kinematic model, and drive the land-air robot to move in the ground motion mode using the trajectory tracking controller in the ground motion mode. The trajectory tracking controller in flight mode of S5 is specifically as follows: in, and Let these represent the state vector and control input vector of the land-air robot in flight mode, respectively. , and Representing the three-dimensional position, velocity, and Euler angles respectively. Represents the set of real numbers. 、 and These represent the desired pitch angle control input, the desired roll angle control input, and the desired thrust input, respectively. This represents the first dynamic model in S1. Indicates 0 to The optimal control input at any given time. and They represent t Time and The expected state vector at time 10:

00. , , ， ， , These represent the control input vectors respectively. The upper and lower bounds, 、 、 These represent the weighted matrices for the state, input, and final state, respectively. Indicates constraint; , , The formal specifications all represent the weighted Euclidean inner product; Represents the moment of inertia matrix; symbol Denotes the first derivative; The robust balance controller in S6 is specifically as follows: In the formula, For control vector For state vectors, It is the desired state vector of the land-air robot in the ground motion mode, where and These represent the desired position and desired velocity, respectively. It is a feedback matrix; feedback matrix The specific calculation formula is as follows: in, For the control matrix, It is a symmetric positive definite matrix, representing the cost associated with the state vector; Let be a positive definite matrix, and let be a solution to the continuous-time algebraic Ricati equation; and let be a positive definite matrix. The solution can be obtained using the following formula: 。 2. The control method for a land-air robot with high ground adaptability according to claim 1, characterized in that, The motion module includes four joint motors (22), two drive motors, two drive wheels (214), and four auxiliary wheels (23); the four joint motors (22) are evenly distributed on the left and right sides of the land-air robot, and the two joint motors (22) on the same side are distributed along the front-back direction; the two drive wheels (214) are respectively mounted on the two drive motors; The five-bar linkage (21) includes two thigh rods (211), a front lower leg rod (212), a rear lower leg rod (213), and two drive wheels (214). One side of each of the two thigh rods (211) is fixed to the output shaft of two joint motors (22) on the same side, and the other side is rotatably connected to one side of the front lower leg rod (212) and the rear lower leg rod (213). The other side of each of the front lower leg rod (212) and the rear lower leg rod (213) is connected to one of the drive motors. The two drive wheels (214) are respectively arranged between one of the thigh rods (211) and the front lower leg rod (212), and between the other thigh rod (211) and the rear lower leg rod (213).

3. The control method for a land-air robot with high ground adaptability according to claim 1, characterized in that, The autonomous driving module (30) includes: An onboard computer (31) is used to make action decisions for the land and air robots; Flight controller (32), electrically connected to onboard computer (31), is used to control aerodynamic unit (10); The data transmission radio (33) is electrically connected to the onboard computer (31) and is used to wirelessly transmit the operating status information of the land and air robot to an external ground control station. The remote control receiver (34) is electrically connected to the onboard computer (31) and is used to receive control commands issued by the receiver remote control held by the operator and transmit them to the onboard computer (31). The power supply (35) is installed above the ground motion unit (20) and is used to power the entire land-air robot.

4. The control method for a land-air robot with high ground adaptability according to claim 3, characterized in that, The first dynamic model in S1 is as follows: In the formula, Indicates the body coordinate system. Indicates an inertial coordinate system. This represents the velocity vector in the flight mode within the inertial coordinate system. This represents the rotation matrix from the inertial coordinate system to the body coordinate system during flight mode. This represents the angular velocity in flight mode within the aircraft's coordinate system. Represents gravitational acceleration. This indicates the total mass of the land and air robots. The matrix representing the inverse of the moment of inertia matrix. This represents the total thrust generated by the propellers in the body coordinate system for the land-air robot. This represents the air resistance experienced by a land-to-air robot in an inertial coordinate system. Represents the third reference vector. T Indicates transpose. This represents the total torque generated by the propeller in the body coordinate system.

5. The control method for a land-air robot with high ground adaptability according to claim 4, characterized in that, The derivation of the linearized nonlinear dynamic model and the linearized second dynamic model in S2 is as follows: In the formula, This represents a nonlinear dynamic model of the ground motion modes of a land-air robot. , , These are the vertical deflection angle of the swing arm and the horizontal tilt angle of the land-air robot, respectively. The swing arm is the line connecting the center point of the drive wheel (214) and the midpoint of the line connecting the two joint motors (22) on the same side. and These represent the angular velocity of the pendulum around the center of the drive wheel (214) and the angular velocity of the land-air robot around the center of the hip joint, respectively. The center of the hip joint is the midpoint of the line connecting the two joint motors (22). and These represent displacement and velocity in the mechanical system, respectively. , It is the torque of the drive wheel (214) and the vertical deflection angle of the rocker arm. Consistent direction The torque of the joint motor (22) This represents the system output of the land and air robots; Represents the state matrix; The control matrix represents the state matrix; and the state matrix represents the control matrix. and control matrix The specific calculation formula is as follows: in, , These are the equilibrium points of the state vectors and control vectors of the land and air robots, respectively. This indicates the partial derivative sign.

6. The control method for a land-air robot with high ground adaptability according to claim 5, characterized in that, The first kinematic model in S3 is as follows: In the formula, , These represent the state vector and control input vector of the land-air robot in its ground operation mode, respectively. , , These represent the robot's coordinates in the world coordinate system. x and y Displacement components and yaw angle in the direction, , These represent the desired velocity and angular velocity, respectively.

7. The control method for a land-air robot with high ground adaptability according to claim 6, characterized in that, The five-bar kinematic model in S4 is as follows: In the formula, Represents the kinematic model of the five-bar linkage; pendulum state vector , angle vector , and These represent the lengths of the first thigh bar (211). The length of the second thigh bar on the same side (211) The lines they are on are respectively with The included angle in the positive direction of the axis, the length of the first thigh rod (211) The line connecting the first joint motor (22) where the first thigh bar (211) is located and the nearest auxiliary wheel (23); the length of the second thigh bar (211). The line connecting the second joint motor (22) and the second auxiliary wheel (23) connected to the second thigh rod (211) is indicated; This refers to the length of the swing arm on the land-and-air robot, or the leg height. Indicates leg height The line containing and The angle between the positive axis and the positive axis.

8. The control method for a land-air robot with high ground adaptability according to claim 7, characterized in that, The trajectory tracking controller in the human ground motion mode of S8 is expressed by a formula, as follows: In the formula, Indicates 0 to The optimal control input at any given time. and Representing time t and The desired state at any given time. 、 、 、 express The upper and lower limits, , and These represent the weighted matrices for the state, input, and final state, respectively.

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