Research On Slip Recognition And Control Of Wheeled Mobile Robots In Complex Environments

Wheeled mobile robot(WMR)is a typical non-holonomic system.Due to non-holonomic constraints,the motion control of WMR is difficult which is a hot issue in the field of mobile robot in recent years.Wheeled mobile robots are widely used in scientific research,risk prevention,rescue and other fields because of their stable structure an d strong environmental adaptability.This paper mainly studies the control strategy when the wheeled mobile robot experiences longitudinal slipping interference in a complex environment,and systematically discusses the key issues such as modeling method of wheeled mobile robot,adaptive tracking controller design,slipping parameter identification and prediction and system stability analysis.The main work is summarized as follows:(1)Establishing a slip model for wheeled mobile robots.In view of the problem that the slipping of the wheel of the mobile robot in the complex environment,the idea assumption of“pure rolling without slipping” is abandoned,and the controller designed based on the ideal constraint model is not available.This paper analyzes the slip characteristics.and the slipping phenomenon is described by introducing the slipping parameter to establish the kinematic model of the wheeled mobile robot combined with the environment.(2)Designing an adaptive controller for wheeled mobile robots.Based on the model of position and attitude error and backstepping method of wheeled mobile robot,the adaptive trajectory tracking controller is designed,and the Lyapunov function is constructed to prove the stability of the designed controller,and the unknown control parameters in the controller are determined by real-time online tuning method through pole placement strategy.Finally,for the unknown slipping parameter,design a sliding model observer base on the sliding mode variable structure control theory to estimate the slipping parameters,and the convergence of the observer is analyzed.(3)Proposing a vision-based sliding parameter prediction scheme.In view of the slip phenomenon caused by insufficient tire adhesion when the wheeled mobile robot is working in a complex environment,the problem of control lag is caused by the control after the slip occurs.This paper proposes a vision-based sliding parameter prediction scheme.The specific method is to use the camera to collect the color image information of the road ahead,and identify the road type information through the trained SVM multi-classifier,and then match the slipping parameter increment table with the information,getting the predicted value of the slipping parameter.Finally,the slipping parameter fusion scheme is designed,and the value of the observer and the predicted value of the classifier are combined to estimate the unknownslipping parameters in the controller,thereby achieving early control.(4)Simulation and experimental verification.In order to verify the effectiveness of the above-mentioned adaptive controller designed for wheeled mobile robot while the drive wheel slipping,this paper builds a module based on MATLAB/simulink simulation platform,selects two reference tracks of straight line and circular shape for tracking control simulation verification,the simulation results show that the control effect after fusion is optimal in many proposed solutions.And a Type(2,0)wheeled mobile robot platform is experimentally verified,the experimental results show that effectiveness of the tracking controller.