Research On Robot Formation Based On Sliding Mode Elimination Chattering Algorithm

Robot collaborative motion,with high efficiency,flexibility and low cost,applies to the problem that a single robot can ‘t solve,also applies to the complex work environment.Therefore,the robot formation control,as an important direction of artificial intelligence control,has been widely concerned by scholars.Robot formation model is a typical nonlinear system,and sliding mode variable structure control is an effective nonlinear control technology,which has strong robustness to external noise disturbance and parameter disturbance.However,sliding mode control needs the system state switch near the slip surface with high frequency,which will cause chattering to the system inevitably.In this paper,the robot formation is based on the model of leader-follower,using the Pioneer3-AT robot as the leader and the Amigo Bot-sh robot as the follower to form a multi-robot formation system.The model is established for the formation system,and the sliding mode control algorithm with chattering suppress is applied to the formation system.The stability of the system is analyzed mathematically and its rationality is verified by MATLAB and MobiledSim simulation software.Finally,experiments were performed on Pioneer3-AT mobile robot and AmigoBot-sh mobile robot.The main work of this paper is as follows:First of all,this paper establishes a robot formation model based on the leader-follow in the Cartesian coordinate system,which can avoid the problem of singular point in the polar coordinates.In order to weaken the chattering caused by sliding mode control,a sliding mode control method with gain-schedule and improved boundary layer is proposed for the established robot formation model.This method can make the control input continuous if the external disturbance or the disturbance amplitude is very small,thus weakening the system chattering and does not affect the robustness of the system.Both MobileSim simulation and experiment verified the effectiveness of the control method.Secondly,for a system with uncertain disturbance,if the symbolic function in the sliding mode control is directly made continuous,the robustness of the system will be affected.In this paper,we assume that the external uncertain disturbance is bounded and the pace of change is very slow.A sliding mode adaptive control algorithm with sliding mode disturbance observer is proposed.The uncertain disturbance of the system is compensated by the output of the sliding mode disturbance observer,so that even if a saturated continuous function is used instead of the sign function in the sliding mode control,the robustness of the system can still be guaranteed.Therefore,the system chattering can be suppressed without affecting other control performance.MATLAB simulation verifies the effectiveness of the control algorithm.Finally,this paper proposes a method of terminal sliding mode control with adaptive boundary layer,which does not need to assume that uncertain disturbance change slowly,therefore making the algorithm more suitable.Boundary layer adaptive method can automatically adjust the width of boundary layer according to the state of the system,so the method can weaken the system chattering at the same time can make the system quickly convergence.The terminal sliding mode control method is introduced to speed up the tracking rate of the system,which makes up the hysteresis when using the normal sliding mode control algorithm to track a varying angular velocity.MATLAB and MobileSim verify the effectiveness of the control method.