A nonholonomic wheeled mobile robot discontinuous tracking control method and system

Abstract

The application discloses a kind of discontinuous tracking control method and system of nonholonomic wheeled mobile robot, belong to mobile robot control technical field.It includes according to the motion characteristics of nonholonomic wheeled robot, the kinematic model of nonholonomic wheeled robot is acquired;According to kinematic model, reference trajectory and the position of nonholonomic wheeled robot, the trajectory tracking error equation of nonholonomic wheeled robot is acquired;According to trajectory tracking error equation, the trajectory tracking error of nonholonomic wheeled robot is acquired;Design discontinuous trajectory tracking controller, according to trajectory tracking error, discontinuous trajectory tracking controller executes continuous control or discontinuous control to nonholonomic wheeled mobile robot, to realize the trajectory tracking of nonholonomic wheeled mobile robot.Can guarantee the premise of tracking control effect, effectively solve bandwidth resource occupation problem in mobile robot tracking control, improve information transmission efficiency, reduce control cost.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of mobile robot control, and particularly relates to a discontinuous tracking control method and system for a nonholonomic wheeled mobile robot. BACKGROUND

[0002] The statements in this section merely provide background information related to the present application and do not necessarily constitute the prior art.

[0003] A mobile robot is a highly intelligent system capable of continuous real-time autonomous motion in indoor, outdoor and other environments, integrating functions such as information perception, dynamic decision and control planning. Common mobile robots include wheeled, legged and tracked robots. Compared with other mobile robots, wheeled mobile robots have the advantages of simple structure, high flexibility and strong operation performance, and have a wide range of applications. For example, small automatic guided vehicles in assembly lines and logistics warehouses, inspection robots for intelligent inspection of unattended substations, household cleaning robots developed by Hitachi, DC06 autonomous vacuum cleaning robots developed by Dyson, intelligent wheelchairs developed by Aachen University of Technology, and intelligent tour guide robots developed by Haier-Harbin Institute of Technology Robot Technology Company, etc. are all wheeled mobile robots.

[0004] In addition, existing planetary exploration robots also generally adopt wheeled mobile structures, such as the lunar rover independently developed by China. In the motion control of wheeled mobile robots, it is generally assumed that the wheels only undergo pure rolling without lateral or longitudinal sliding, resulting in nonholonomic constraints on the system. For a general holonomic system, the holonomic constraint condition can be used to solve several state variables, and the original system can be converted into a low-dimensional unconstrained system; however, the nonholonomic system has non-integrability and cannot be converted into a geometric constraint by integration. At the same time, the nonholonomic system does not satisfy the necessary condition of Brockett smooth state feedback stabilization, and there is no smooth (even continuous) static or dynamic feedback stabilization control, thus bringing greater challenges to the motion control of mobile robots. Therefore, the motion control of nonholonomic mobile robots has important theoretical significance and practical value.

[0005] According to different control targets, the motion control problem of the nonholonomic mobile robot can be roughly divided into point stabilization, trajectory tracking and path tracking. Among them, the point stabilization is to make the nonholonomic system starting from a given initial state to reach and stabilize at any given target state, also known as attitude stabilization or attitude adjustment, etc.; the trajectory tracking control is to realize that the robot starting from a given initial state can track the reference trajectory changing with time in real time; the path tracking control is to ensure that the robot starting from any given initial state can reach and follow the specified path, but it does not require when to reach which point. The present application mainly aims at the trajectory tracking control problem of the nonholonomic mobile robot, and the reference trajectory considered does not contain a static configuration, i.e. the nonholonomic system does not contain a static motion, which avoids the case of not satisfying the Brockett necessary condition.

[0006] It is noted that at present, regarding the trajectory tracking control of the mobile robot, most of the continuous state feedback controllers are designed based on the methods such as sliding mode control, fuzzy control, adaptive control and Backstepping, which need to continuously obtain the real-time position information of the robot, estimate the tracking error, output the feedback control signal and adjust the motion state of the robot, and the robustness is poor. Especially in the cooperative control of multiple mobile robots, such tracking strategy relying on continuous feedback control only will occupy a large amount of communication and control resources, and the efficiency is low. SUMMARY

[0007] In order to solve the problems of the prior art, the present application provides a nonholonomic wheeled mobile robot discontinuous tracking control method, system, electronic equipment and computer readable storage medium, which applies the discontinuous control technology to the trajectory tracking control of the mobile robot, effectively improves the flexibility and adaptability of the controller design, and further solves the bandwidth resource occupation problem in the tracking control of the mobile robot, improves the information transmission efficiency and reduces the control cost under the premise of ensuring the trajectory tracking control effect.

[0008] In a first aspect, the present application provides a nonholonomic wheeled mobile robot discontinuous tracking control method.

[0009] The nonholonomic wheeled mobile robot discontinuous tracking control method comprises the following steps:

[0010] According to the motion characteristics of the nonholonomic wheeled robot, a kinematic model of the nonholonomic wheeled robot is obtained;

[0011] According to the kinematic model, the reference trajectory and the position of the nonholonomic wheeled robot, a trajectory tracking error equation of the nonholonomic wheeled robot is obtained; and according to the trajectory tracking error equation, a trajectory tracking error of the nonholonomic wheeled robot is obtained.

[0012] The discontinuous trajectory tracking controller is designed to perform continuous control or discontinuous control on the nonholonomic wheeled mobile robot according to a trajectory tracking error, so as to realize trajectory tracking of the nonholonomic wheeled mobile robot.

[0013] Further, the kinematic model of the nonholonomic wheeled robot is obtained according to motion characteristics of the nonholonomic wheeled robot.

[0014] According to the motion environment of the nonholonomic wheeled robot, an inertial coordinate system is defined, and position information of the nonholonomic wheeled robot is determined.

[0015] According to Newton's second law and the position information of the nonholonomic wheeled robot, the kinematic model of the nonholonomic wheeled robot is obtained.

[0016] Further, the kinematic model of the nonholonomic wheeled robot is expressed as:

[0017]

[0018] Wherein, v is the linear velocity of the nonholonomic wheeled robot, ω is the angular velocity of the nonholonomic wheeled robot, and θ is the azimuth angle of the nonholonomic wheeled robot.

[0019] Further, the trajectory tracking error equation of the nonholonomic wheeled robot is obtained according to the kinematic model, the reference trajectory and the nonholonomic wheeled robot trajectory.

[0020] According to the position information of the reference point in the inertial coordinate system and the distance from the control point to the center of mass of the nonholonomic wheeled robot, an error vector between the actual pose and the virtual pose is defined, and a velocity vector of the reference point in the body coordinate system is obtained according to the error vector between the actual pose and the virtual pose.

[0021] According to the velocity vector of the reference point in the body coordinate system, the velocity vector of the reference point in the inertial coordinate system and the velocity vector of the nonholonomic wheeled robot trajectory in the inertial coordinate system, the trajectory tracking error equation is obtained.

[0022] Further, the trajectory tracking error equation is expressed as:

[0023]

[0024] Wherein, v is the linear velocity of the nonholonomic wheeled robot, ω is the angular velocity of the nonholonomic wheeled robot, and θ is the azimuth angle of the nonholonomic wheeled robot, is the x-coordinate of the error vector between the actual pose and the virtual pose in the body coordinate system of the nonholonomic wheeled mobile robot, is the y-coordinate of the error vector between the actual pose and the virtual pose in the body coordinate system of the nonholonomic wheeled mobile robot, is a moving speed of the reference point P in the x direction in the inertial coordinate system, is a moving speed of the reference point P in the y direction in the inertial coordinate system, and d is a distance of the control point N relative to the center of mass point M of the nonholonomic wheeled mobile robot.

[0025] Further, the design of the discontinuous trajectory tracking controller, according to the trajectory tracking error, the discontinuous trajectory tracking controller performs continuous control or discontinuous control on the nonholonomic wheeled mobile robot, including:

[0026] The design of the discontinuous trajectory tracking controller divides the action time of the discontinuous trajectory tracking controller into multiple control intervals according to the period;

[0027] A closed-loop feedback control subinterval and an open-loop control subinterval are set in each control interval;

[0028] If the trajectory tracking error belongs to a preset threshold range, according to the estimated tracking error of the nonholonomic wheeled mobile robot, the closed-loop feedback control subinterval is processed to realize continuous control of the nonholonomic wheeled mobile robot;

[0029] If the trajectory tracking error does not belong to the preset threshold range, according to the trajectory tracking error of the nonholonomic wheeled mobile robot, the open-loop control subinterval and the closed-loop feedback subinterval are alternately processed to realize discontinuous control of the nonholonomic wheeled mobile robot.

[0030] Further, it further includes:

[0031] According to the kinetic characteristics of the nonholonomic wheeled mobile robot in continuous control and discontinuous control, a Lyapunov function is constructed to estimate the energy change of the trajectory tracking error.

[0032] In a second aspect, the present application provides a nonholonomic wheeled mobile robot discontinuous tracking control system;

[0033] A nonholonomic wheeled mobile robot discontinuous tracking control system includes:

[0034] The kinematic model construction module is configured to obtain the kinematic model of the nonholonomic wheeled robot according to the motion characteristics of the nonholonomic wheeled robot;

[0035] The trajectory tracking error equation construction module is configured to obtain the trajectory tracking error equation of the nonholonomic wheeled robot according to the kinematic model, the reference trajectory and the position of the nonholonomic wheeled robot, and obtain the trajectory tracking error of the nonholonomic wheeled robot according to the trajectory tracking error equation;

[0036] The trajectory tracking control module is configured to design a discontinuous trajectory tracking controller, and the discontinuous trajectory tracking controller performs continuous control or discontinuous control on the nonholonomic wheeled mobile robot according to a trajectory tracking error, so as to realize trajectory tracking of the nonholonomic wheeled mobile robot.

[0037] In a third aspect, the present application provides an electronic device;

[0038] An electronic device comprises a memory and a processor, and computer instructions stored in the memory and running on the processor, when the computer instructions are run by the processor, the steps of the nonholonomic wheeled mobile robot discontinuous tracking control method are completed.

[0039] In a fourth aspect, the present application provides a computer readable storage medium;

[0040] A computer readable storage medium is used to store computer instructions, when the computer instructions are executed by the processor, the steps of the nonholonomic wheeled mobile robot discontinuous tracking control method are completed.

[0041] Compared with the prior art, the present application has the following beneficial effects:

[0042] 1. The technical scheme provided by the present application applies discontinuous control technology to trajectory tracking control of a mobile robot; compared with trajectory tracking control based on continuous state feedback, only closed-loop state feedback is used in a specific interval, and open-loop control is relied on in the remaining interval, on the basis of general control parameters, a control interval duty cycle parameter is added, and the flexibility and adaptability of controller design are effectively improved.

[0043] 2. The technical scheme provided by the present application can further solve the bandwidth resource occupation problem in mobile robot tracking control, improve information transmission efficiency, and reduce control cost under the premise of ensuring trajectory tracking control effect. BRIEF DESCRIPTION OF DRAWINGS

[0044] The drawings constituting a part of the present application are used to provide further understanding of the present application, and the illustrative embodiments of the present application and the description thereof are used to explain the present application, and do not constitute improper limitation on the present application.

[0045] Figure 1 The flowchart provided for the embodiments of the present application;

[0046] Figure 2 The motion diagram of the nonholonomic wheeled mobile robot provided for the embodiments of the present application. DETAILED DESCRIPTION

[0047] It should be noted that the following detailed description is exemplary in nature and is intended to provide further description of the application. Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs.

[0048] It is also to be understood that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting, as the scope of the application will be limited only by the appended claims.

[0049] The embodiments in the application and the features in the embodiments can be combined with each other without conflict.

[0050] Term explanation:

[0051] (1) Discontinuous control system: Discontinuous control system is derived from the discontinuous control of continuous system and the control of discontinuous system. The former is composed of continuous uncontrolled system, discontinuous controller and control switching mechanism, such as sample control system, pulse modulation control system, pulse control system, sliding mode control system, etc. The latter is composed of multi-modal system, continuous or discontinuous controller and switching mechanism between different modes, such as robot control system, traffic flow control system, fuzzy control system, logic-based switching control system, etc.

[0052] (2) Wheeled mobile robot: Wheeled mobile robot is a robot with special configuration, which moves in the way of using wheels. It is a complex system integrating perception system, motion system, work system and control system. It understands its own changes and external environment changes through sensors, then decomposes and allocates tasks according to the original task, plans, and finally controls the action of the action execution mechanism, so as to change the external environment or the relationship between the external environment and the robot itself.

[0053] (3) Trajectory tracking control: Trajectory tracking control is to reach the originally set trajectory position through the control of trajectory tracking system within a specified time.

[0054] (4) State feedback control: State feedback control is to multiply each state variable of the system by the corresponding feedback coefficient, and feed back to the input end and add the reference input, and the sum is used as the control signal of the controlled system.

[0055] (5) Backstepping: also known as backstepping design method, is a systematic controller synthesis method for uncertain systems, which is a regression design method combining the selection of Lyapunov function and the design of controller. It starts from the lowest order differential equation of the system, introduces the concept of virtual control, and designs the virtual control that meets the requirements step by step, and finally designs the real control law.

[0056] Embodiment one

[0057] In the prior art, the trajectory tracking control of the nonholonomic wheeled mobile robot needs to continuously obtain real-time position information of the robot, estimate tracking error, output feedback control signal, and adjust the motion state of the robot, which has poor robustness, occupies a large amount of communication and control resources, and has low efficiency; therefore, the present application provides a nonholonomic wheeled mobile robot discontinuous tracking control method, which applies discontinuous control technology theory to the tracking control of the mobile robot, and saves communication resources by coupling the dynamic of the closed-loop and open-loop control systems without communication connection in a specific interval.

[0058] Next, combined with Figures 1-2 A nonholonomic wheeled mobile robot discontinuous tracking control method disclosed in the present embodiment will be described in detail. The nonholonomic wheeled mobile robot discontinuous tracking control method comprises the following steps:

[0059] S1, according to the motion characteristics of the nonholonomic wheeled robot, obtaining the kinematic model of the nonholonomic wheeled robot, comprising:

[0060] S101, according to the motion environment of the nonholonomic wheeled robot, defining an inertial coordinate system and determining the position information of the nonholonomic wheeled robot.

[0061] S102, according to Newton's second law and the position information of the nonholonomic wheeled robot, obtaining the kinematic model of the nonholonomic wheeled robot.

[0062] As shown in the nonholonomic wheeled mobile robot as shown in Figure 2 The specific process is as follows:

[0063] First, according to the motion environment of the nonholonomic wheeled mobile robot, reasonable assumptions are made, and an inertial coordinate system F=(x M ,y M ,θ) is defined, wherein x M ,y M ,θ are the horizontal coordinate, vertical coordinate and azimuth angle of the nonholonomic wheeled mobile robot, respectively.

[0064] During low-speed motion, the kinematic model of the nonholonomic wheeled mobile robot can be obtained according to Newton's second law as follows

[0065]

[0066] where v, ω are the linear and angular velocities of the nonholonomic wheeled mobile robot respectively.

[0067] It is assumed that during this process, the wheels of the nonholonomic wheeled mobile robot do not slip relative to the ground, and the center of mass of the nonholonomic wheeled mobile robot is located at the axis position between the two wheels.

[0068] Let N be a point connected to the nonholonomic wheeled mobile robot, the coordinates of which in the inertial coordinate system F are (x N ,y N ), and the coordinates of which in the body coordinate system F M with the center of mass of the nonholonomic wheeled mobile robot as the origin are (d, 0), d being the distance of the control point N from the center of mass M of the nonholonomic wheeled mobile robot. The trajectory tracking problem considered in this embodiment is to find a suitable intermittent control law for v and ω, so that the control point N follows the trajectory of the reference point P. By realizing the tracking of the control point N to the reference point P, the center of mass M of the nonholonomic wheeled mobile robot ultimately tracks the point P. The coordinates of P in the inertial coordinate system F and the body coordinate system F M are (x P ,y P ) and

[0069] In addition, since the discontinuous control proposed below is applicable to low-speed trajectory tracking, it will cause a large tracking error and poor control effect when the reference point P moves at high speed. Therefore, a hypothetical condition is added to constrain the movement speed of P, assuming

[0070]

[0071] where v is the movement speed of the reference point P in the x direction in the inertial coordinate system, v max is the movement speed of the reference point P in the y direction in the inertial coordinate system, and v max > 0.

[0072] Considering that the controller designed based on the kinematic model has control inputs of generalized velocities and angular velocities, the influence of the dynamics characteristics such as the mass and moment of inertia of the nonholonomic system on the controller is ignored, and the controller is generally applicable to trajectory tracking control problems under low-speed motion conditions.

[0073] S2, according to the kinematic model, the reference trajectory and the position of the nonholonomic wheeled mobile robot, obtaining the trajectory tracking error equation of the nonholonomic wheeled mobile robot; according to the trajectory tracking error equation, obtaining the trajectory tracking error of the nonholonomic wheeled mobile robot. Including:

[0074] S201, defining an error vector between the actual pose and the virtual pose according to the position information of the reference point in the inertial coordinate system and the distance from the control point to the centroid of the nonholonomic wheeled robot, and obtaining a velocity vector of the reference point in the body coordinate system according to the error vector between the actual pose and the virtual pose.

[0075] S202, obtaining a trajectory tracking error equation according to the velocity vector of the reference point in the body coordinate system, the velocity vector of the reference point in the inertial coordinate system and the velocity vector of the nonholonomic wheeled robot in the inertial coordinate system.

[0076] S203, obtaining a trajectory tracking error based on the trajectory tracking error equation according to the linear velocity, the angular velocity and the azimuth angle of the nonholonomic wheeled mobile robot.

[0077] Exemplarily, the error vector r between the actual pose and the virtual pose is represented as NP The coordinates of the point P in the inertial coordinate system F can be obtained. M The velocity vector of the point P in F

[0078]

[0079] In addition, let v P be the velocity vector of the reference point P in the inertial coordinate system F, and v M be the velocity vector of the nonholonomic wheeled mobile robot M in the inertial coordinate system F.

[0080] Then, from the Newton kinematics law of the nonholonomic wheeled mobile robot, it can be obtained that

[0081]

[0082] where w M = ω · k0 is the instantaneous rotation rate of F M relative to F, r MP represents the vector from M to P, and satisfies

[0083]

[0084] v M = v · i M (6)

[0085]

[0086] Then, the trajectory error tracking equation can be obtained from the above formula (4) and is represented as:

[0087]

[0088] ​S3, design a discontinuous trajectory tracking controller, according to the trajectory tracking error, the discontinuous trajectory tracking controller performs continuous control or discontinuous control on the nonholonomic wheeled mobile robot to realize the trajectory tracking of the nonholonomic wheeled mobile robot. Comprise:

[0089] S301, design a discontinuous trajectory tracking controller, divide the action time of the discontinuous trajectory tracking controller into multiple control intervals.

[0090] S302, set a closed-loop feedback control sub-interval and an open-loop control sub-interval in each control interval; if the trajectory tracking error belongs to the preset threshold range, according to the estimated tracking error of the nonholonomic wheeled mobile robot, process in the closed-loop feedback control sub-interval to realize the continuous control of the nonholonomic wheeled mobile robot; if the trajectory tracking error does not belong to the preset threshold range, according to the trajectory tracking error of the nonholonomic wheeled mobile robot, process alternately through the open-loop control sub-interval and the closed-loop feedback control sub-interval to realize the discontinuous control of the nonholonomic wheeled mobile robot.

[0091] For example, the specific process is as follows:

[0092] First, consider the tracking control of a straight line trajectory, divide the controller action time into multiple control intervals, and set a closed-loop feedback control sub-interval and an open-loop control sub-interval in each control interval. Among them, in the closed-loop control sub-interval, mainly use the nonlinear state feedback control designed based on the Backstepping method for continuous control; in the open-loop control sub-interval, mainly rely on the free motion of the nonholonomic mobile robot system.

[0093] Therefore, for a given parameter p, p>0, define the threshold range Ω ρ :

[0094]

[0095] For , the tracking error is large, at this time, continuous control input is performed in the closed-loop feedback control sub-interval:

[0096]

[0097] The purpose of quickly reducing the tracking error can be achieved.

[0098] For , consider discontinuous control input in the open-loop control sub-interval and the closed-loop control sub-interval:

[0099]

[0100]

[0101] where, k1,k2>0, k 1′ = k1 / Δ, k 2′ = k2 / Δ, T>0, Δ∈(0,T) is the width of the control interval.

[0102] Further, in some embodiments, in order to better design the discontinuous tracking controller, the energy of the nonholonomic wheeled mobile robot system is estimated based on Lyapunov stability theory.

[0103] Specifically, the dynamic characteristics of the nonholonomic wheeled mobile robot in the closed-loop state control sub-interval and the open-loop control sub-interval are analyzed, and by constructing a proper Lyapunov function to estimate the energy change of the error system, the following conclusion can be obtained.

[0104] Given a reference trajectory (x P , y P ), if there exist k1, k2, T, ρ>0 such that

[0105] 2ρv max T<k1∨|d|k2 (12)

[0106] then the tracking error converges to 0 asymptotically under the discontinuous control (11) and the continuous control (10).

[0107] The following proves this conclusion:

[0108] Let and be the closed-loop trajectory of the nonholonomic wheeled mobile robot with the initial tracking error .

[0109] Let

[0110]

[0111] Without loss of generality, let In this case, from equations (8) and (10), we have

[0112]

[0113] In addition, for t∈[kT+Δ,(k+1)T), we also have

[0114]

[0115] From the definition of Ω ρ , we have

[0116]

[0117] Therefore, from equations (14) and (16), we can obtain

[0118]

[0119] Therefore, there exists σ>0 satisfying 2(k1∨|d|k2)-4ρv max T≥σ, therefore we have

[0120] V((k+1)T)≤e -σ V(kT) <V(kT) (18)

[0121] In addition, there exists Make V(KT)≤1 / (2ρ) 2 ), and have

[0122]

[0123] Right now, From equation (10), we can obtain

[0124]

[0125] Therefore, as t→∞,

[0126] Next, taking (0.1sin t, 0.1cos t) as an example, the effectiveness of the discontinuous tracking control method for the nonholonomic wheeled mobile robot described in this embodiment is further illustrated. Table 1 presents the discontinuous tracking control input with a duty cycle of 70%, as well as the position and velocity variable data of the wheeled mobile robot under this control action. According to the data in Table 1, it can be observed that when the control cycle length is selected as 1 and the duty cycle is 70%, the discontinuous trajectory tracking control can achieve rapid convergence of state variables. Moreover, compared with the current tracking control based on continuous state feedback, it can allow "zero control input" in a 30% interval. The above results show that the discontinuous control technology of the present invention can effectively reduce the consumption and dependence on communication resources and improve the utilization rate of control resources while ensuring the tracking control effect.

[0127] Table 1. State and control input under discontinuous control and tracking control

[0128]

[0129]

[0130]

[0131]

[0132]

[0133]

[0134]

[0135] Embodiment Two

[0136] The embodiment discloses a nonholonomic wheeled mobile robot discontinuous tracking control system, comprising:

[0137] The kinematic model construction module is configured to: acquire a kinematic model of the nonholonomic wheeled robot according to motion characteristics of the nonholonomic wheeled robot.

[0138] The trajectory tracking error equation construction module is configured to: acquire a trajectory tracking error equation of the nonholonomic wheeled robot according to the kinematic model, a reference trajectory and a position of the nonholonomic wheeled robot; and acquire a trajectory tracking error of the nonholonomic wheeled robot according to the trajectory tracking error equation.

[0139] The trajectory tracking control module is configured to: design a discontinuous trajectory tracking controller; and according to the trajectory tracking error, the discontinuous trajectory tracking controller performs continuous control or discontinuous control on the nonholonomic wheeled mobile robot to realize trajectory tracking of the nonholonomic wheeled mobile robot.

[0140] It should be noted that the kinematic model construction module, the trajectory tracking error equation construction module and the trajectory tracking control module correspond to the steps in Embodiment One, and the above modules have the same examples and application scenarios as the corresponding steps, but are not limited to the content disclosed in Embodiment One. It should be noted that the above modules can be executed in a computer system such as a set of computer executable instructions as part of the system.

[0141] Embodiment Three

[0142] The embodiment three of the present application provides an electronic device, comprising a memory and a processor, and computer instructions stored in the memory and running on the processor, when the computer instructions are executed by the processor, the steps of the nonholonomic wheeled mobile robot discontinuous tracking control method are completed.

[0143] Embodiment Four

[0144] The embodiment four of the present application provides a computer readable storage medium for storing computer instructions, when the computer instructions are executed by the processor, the steps of the nonholonomic wheeled mobile robot discontinuous tracking control method are completed.

[0145] This invention is described with reference to flowchart illustrations and / or block diagrams of methods, apparatus (systems), and computer program products according to embodiments of the invention. It will be understood that each block of the flowchart illustrations and / or block diagrams, and combinations of blocks in the flowchart illustrations and / or block diagrams, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, special-purpose computer, embedded processor, or other programmable data processing apparatus to produce a machine, such that the instructions, which execute via the processor of the computer or other programmable data processing apparatus, generate instructions for implementing the flowchart illustrations and / or block diagrams. Figure 1 One or more processes and / or boxes Figure 1 A device that provides the functions specified in one or more boxes.

[0146] These computer program instructions may also be stored in a computer-readable storage medium that can direct a computer or other programmable data processing device to function in a particular manner, such that the instructions stored in the computer-readable storage medium produce an article of manufacture including instruction means, which are implemented in a process Figure 1 One or more processes and / or boxes Figure 1 The function specified in one or more boxes.

[0147] These computer program instructions may also be loaded onto a computer or other programmable data processing equipment, whereby a series of operational steps are performed to produce a computer-implemented process, thereby providing instructions that execute on the computer or other programmable equipment for implementing the process. Figure 1 One or more processes and / or boxes Figure 1 The steps of the function specified in one or more boxes.

[0148] The descriptions of each embodiment in the above embodiments have different focuses. For parts not described in detail in a certain embodiment, please refer to the relevant descriptions in other embodiments.

[0149] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A discontinuous tracking control method for a nonholonomic wheeled mobile robot, characterized in that, include: Based on the motion characteristics of the nonholonomic wheeled robot, obtain the kinematic model of the nonholonomic wheeled robot; Based on the kinematic model, reference trajectory, and position of the incomplete wheeled robot, the trajectory tracking error equation of the incomplete wheeled robot is obtained; Based on the trajectory tracking error equation, the trajectory tracking error of the nonholonomic wheeled robot is obtained; The process of obtaining the trajectory tracking error equation for the incomplete wheeled robot based on the kinematic model, reference trajectory, and incomplete wheeled robot trajectory includes: Based on the position information of the reference point in the inertial coordinate system and the distance of the control point from the center of mass of the non-holonomic wheeled robot, the error vector between the actual pose and the virtual pose is defined. Based on the error vector between the actual pose and the virtual pose, the velocity vector of the reference point in the body coordinate system is obtained. Based on the velocity vector of the reference point in the body coordinate system, the velocity vector of the reference point in the inertial coordinate system, and the velocity vector of the incomplete wheeled robot trajectory in the inertial coordinate system, the trajectory tracking error equation is obtained. Design a discontinuous trajectory tracking controller. Based on the trajectory tracking error, the discontinuous trajectory tracking controller performs continuous or discontinuous control on the non-holonomic wheeled mobile robot to achieve trajectory tracking of the non-holonomic wheeled mobile robot. The discontinuous trajectory tracking controller is designed such that, based on the trajectory tracking error, the discontinuous trajectory tracking controller performs continuous or discontinuous control on the non-holonomic wheeled mobile robot, including: Design a discontinuous trajectory tracking controller and divide the action time of the discontinuous trajectory tracking controller into multiple control intervals; Within each control interval, a closed-loop feedback control sub-interval and an open-loop control sub-interval are set; If the trajectory tracking error falls within a preset threshold range, the estimated tracking error of the non-holonomic wheeled mobile robot is processed in the closed-loop feedback control sub-interval to achieve continuous control of the non-holonomic wheeled mobile robot. If the trajectory tracking error does not fall within the preset threshold range, the trajectory tracking error of the incomplete wheeled mobile robot is processed alternately in the open-loop control sub-interval and the closed-loop feedback sub-interval to achieve discontinuous control of the incomplete wheeled mobile robot.

2. The discontinuous tracking control method for a non-holonomic wheeled mobile robot as described in claim 1, characterized in that, The process of obtaining the kinematic model of the nonholonomic wheeled robot based on its motion characteristics includes: Based on the motion environment of the incomplete wheeled robot, an inertial coordinate system is defined to determine the position information of the incomplete wheeled robot; Based on Newton's second law and the position information of the nonholonomic wheeled robot, obtain the kinematic model of the nonholonomic wheeled robot.

3. The discontinuous tracking control method for a non-holonomic wheeled mobile robot as described in claim 1, characterized in that, The kinematic model of the nonholonomic wheeled robot is represented as follows: in, The x-coordinate of the incomplete wheeled robot. The vertical coordinate of the incomplete wheeled robot. v For the linear velocity of a non-holonomic wheeled robot, For the angular velocity of a non-holonomic wheeled robot, θ The azimuth angle is for a non-complete wheeled robot.

4. The discontinuous tracking control method for a non-holonomic wheeled mobile robot as described in claim 1, characterized in that, The trajectory tracking error equation is expressed as follows: Where v is the linear velocity of the incomplete wheeled robot. Let θ be the angular velocity of the incomplete wheeled robot, and θ be the azimuth angle of the incomplete wheeled robot. Let x be the x-coordinate of the error vector between the actual pose and the virtual pose in the body coordinate system of the nonholonomic wheeled mobile robot. Let y be the error vector between the actual pose and the virtual pose in the body coordinate system of the nonholonomic wheeled mobile robot. Let P be the velocity of the reference point P in the x-direction in the inertial coordinate system. Let d be the velocity of reference point P in the y-direction in the inertial coordinate system, and d be the distance of control point N relative to the center of mass M of the non-holonomic wheeled mobile robot.

5. The discontinuous tracking control method for a non-holonomic wheeled mobile robot as described in claim 1, characterized in that, Also includes: Based on the dynamic characteristics of nonholonomic wheeled mobile robots under continuous and discontinuous control, a Lyapunov function is constructed to estimate the energy change of trajectory tracking error.

6. A discontinuous tracking control system for a non-holonomic wheeled mobile robot, characterized in that, include: The kinematic model building module is configured to: obtain the kinematic model of the nonholonomic wheeled robot based on its motion characteristics; The trajectory tracking error equation construction module is configured to: obtain the trajectory tracking error equation of the incomplete wheeled robot based on the kinematic model, the reference trajectory, and the position of the incomplete wheeled robot; Based on the trajectory tracking error equation, the trajectory tracking error of the nonholonomic wheeled robot is obtained; The process of obtaining the trajectory tracking error equation for the incomplete wheeled robot based on the kinematic model, reference trajectory, and incomplete wheeled robot trajectory includes: Based on the position information of the reference point in the inertial coordinate system and the distance of the control point from the center of mass of the non-holonomic wheeled robot, the error vector between the actual pose and the virtual pose is defined. Based on the error vector between the actual pose and the virtual pose, the velocity vector of the reference point in the body coordinate system is obtained. Based on the velocity vector of the reference point in the body coordinate system, the velocity vector of the reference point in the inertial coordinate system, and the velocity vector of the incomplete wheeled robot trajectory in the inertial coordinate system, the trajectory tracking error equation is obtained. The trajectory tracking control module is configured to: design a discontinuous trajectory tracking controller, which performs continuous or discontinuous control on the non-holonomic wheeled mobile robot based on the trajectory tracking error, so as to realize the trajectory tracking of the non-holonomic wheeled mobile robot; The discontinuous trajectory tracking controller is designed such that, based on the trajectory tracking error, the discontinuous trajectory tracking controller performs continuous or discontinuous control on the non-holonomic wheeled mobile robot, including: Design a discontinuous trajectory tracking controller and divide the action time of the discontinuous trajectory tracking controller into multiple control intervals; Within each control interval, a closed-loop feedback control sub-interval and an open-loop control sub-interval are set; If the trajectory tracking error falls within a preset threshold range, the estimated tracking error of the non-holonomic wheeled mobile robot is processed in the closed-loop feedback control sub-interval to achieve continuous control of the non-holonomic wheeled mobile robot. If the trajectory tracking error does not fall within the preset threshold range, the trajectory tracking error of the incomplete wheeled mobile robot is processed alternately in the open-loop control sub-interval and the closed-loop feedback sub-interval to achieve discontinuous control of the incomplete wheeled mobile robot.

7. An electronic device, characterized in that, It includes a memory and a processor, as well as computer instructions stored in the memory and running on the processor, which, when executed by the processor, perform the method according to any one of claims 1-5.

8. A computer-readable storage medium, characterized in that, Used to store computer instructions, which, when executed by a processor, perform the method described in any one of claims 1-5.

Images