Study On Sliding Mode Control Of Multi-autonomous Mobile Robot Cooperative Relay Tracking System

Multi-robot systems are mainly used to work cooperatively to complete tasks when individual robots are unable to work effectively in the face of complex problems.The key technique of multi-robot systems is to design a suitable distributed control algorithm so that each robot can interact with other robots to perform specific tasks and behaviors.The actual system contains nonlinear components and communication link interruptions during the execution of the task,which will cause the topology structure to change.Therefore,the study of nonlinear multi-robot systems with switching topology has theoretical and practical significance.However,the research of this type of system is more difficult and the research results of the multi-robot cooperative target relay tracking system that considers both nonlinear and variable topology structures are still insufficient.So,the main research contents of this subject are as follows:(1)In this thesis,the traditional first-order sliding mode control algorithm is fully considered in terms of fast response,strong robustness and easy implementation.A distributed sliding mode controller for coordinated relay tracking of multiple robots is designed.The constraint conditions of the controller parameters,using the average dwell time method of the switching technology,solve the stability analysis problem caused by error jumps in the relay tracking system.Simulation results verify the effectiveness of the designed controller.Compared with the classic distributed control algorithm,the designed controller shortens the tracking time and improves the tracking efficiency.(2)For the second-order nonlinear multi-autonomous mobile robot system under disturbances,an adaptive sliding mode control algorithm is proposed to design the distributed control protocol,in which the upper bound of the disturbance is estimated online by the adaptive law.The multi-Lyapunov function method based on average dwell time is adopted to analyze the stability of the multi-robot relay tracking subsystems and the overall system suffering from tracking error jumps.The final simulation results show that the designed adaptive law can effectively suppress disturbance and successful tracking of the target is realized with designed controller.(3)In view of the complexity of the second-order nonlinear multi-robot system,the system is required to complete the task in a limited time.This paper uses a finite-time control algorithm including high-order sliding mode to design a distributed control protocol.The switching term of the sliding mode control algorithm is included in the derivative of the controller and the control changes from the previous discontinuity to the continuous controller after the integration,which can effectively suppress chattering to a certain extent.The nonsingular terminal sliding mode controller can accurately estimate the limited tracking time while eliminating the singularity.At the same time,the Lyapunov function method based on average dwell time is used to analyze the stability of the subsystems and the overall system.The final simulation results demonstrate that the multi-robot system successfully tracks the target within finite time.(4)A multi-robot collaborative target tracking experiment platform is established based on visual positioning,which includes the design and optimization of a visual positioning system to obtain the accurate positions of multiple mobile robots in real time.In addition,hardware and ROS framework-based software design are finished at the same time.According to the actual parameters,the experimental verification of the basic sliding mode controller is completed on the multi-robot platform.It is shown that the tracking error of the multi-robot system can be converged to zero under the designed distributed control protocol.The positions of multiple robots finally stays stable.