Adaptive Fuzzy Sliding Mode Controller For Trajectory Tracking Control Of A Nonholonomic Mobile Robot

Mobile robot as a new type of tools for human to produce, reducing labor intensity,and improving productivity, and changing the mode of production shows great advantagesand that it will have good development in the future. Since the trajectory tracking controlof mobile robot is an important part of its motion control, the research is of greatsignificance.Early study about trajectory tracking control of the mobile robot is based on thekinematic model. However, the control law cannot control the robot system withparametric and non-parametric uncertainties. Therefore, more research is concentrated onthe dynamic model. In practical applications, the torque is finally provided by the DC drivemotor, and the research about mobile robot with DC motor drive model is relatively less.So this paper uses adaptive fuzzy sliding mode controller to design trajectory trackingcontrol law for nonholonomic mobile robot with parametric and non-parametricuncertainties.Firstly, the paper shows the concept and nature of nonholonomic mobile robot,including nonholonomic system, judgment of nonholonomic and controllability of Pfaffianconstraints. And then the main problems in nonholonomic mobile robot motion control areshowed. Also mathematical models of the mobile robot are presented in the last part ofChapter II, includingthe kinematic model and dynamic model established with any pointon the platform as a reference point and the DC motor drive model.Secondly, Chapter III presents the basic principles for designing backsteppingcontroller. Kinematic model of the mobile robot is simplified by selecting a specialreference point based on the robot kinematic model showed in Chapter II. And then thepaper shows position and orientation error model in local coordinate system, designsLyapunov function and speed input control law utilizing backstepping controller, andproves the system will be asymptotic stability in global coordinate system. Also simulationexamples of tracking the linear trajectory and circular trajectory demonstrate theeffectiveness of the control law designed before. Finally, the basic principles of fuzzy adaptive control and sliding-mode controlalgorithm are showed in Chapter IV. Dynamic model with torque as the input of the mobilerobot is simplified by selecting a special reference point based on the kinematic modelshowed in chapter II, based on which dynamic model with voltage of DC motor as theinput is presented. And then the paper designs sliding mode controller for mobile robotconsidering many uncertainties and disturbances, of which fuzzy adaptive controller isadapted to revise the gain to eliminate the chattering phenomenon of sliding mode controland to overcome the structured and unstructured uncertainties in mobile robot system. Inthe last part of this chapter, the simulations of the mobile robot under the control of theproposed controller in this paper and the ordinary sliding mode controller are showed.Simulation results demonstrate that the proposed control algorithm in this paper has certainadvantage compared with ordinary sliding mode control algorithm.