Trajectory Tracking Control Of An Omnidirectional Mobile Manipulator

As a typical representative of mobile robots,omnidirectional mobile manipulator has both wide workspace and flexible operation ability,and it is widely used in many fields such as in scientific investigation,industrial,manufacturing,education,medical and so on.However,it is difficult to establish a precise mathematical model for the mobile manipulator,which is a multi-input multi-output time-varying system with highly complex nonlinearity and strong coupling.What's more,because of the existence of various uncertain factors,the controller design and study of the control mothed are difficult in practice control.Therefore,how to realize the precise trajectory tracking control problem of the omnidirectional mobile manipulator has great theoretical and practical value.In this paper,a model-based control system and a model free control system are studied for trajectory tracking control of an omnidirectional mobile manipulator,with the presence of parameter uncertainties and external disturbances.The core research contents are as follows:Firstly,the mathematical model of the omnidirectional mobile manipulator built by the laboratory is deduced.The kinematics model is derived by geometric analysis and the dynamics model is derived based on Lagrangian dynamic equation.The dynamic model has more practical value with the consideration of the dynamic characteristics of the motor.Then for the shortage of the traditional extended state observer,an improved ESO is designed,and the estimated performance of the disturbance is improved.A non-singular terminal sliding mode controller is designed for the nonlinear system,and the stability is guaranteed by Lyapunov theory.Simulation and experiment results demonstrate the effectiveness and robustness of the proposed control algorithm.Finally,since the modeling process is complex,and there are unmodeled dynamic,and parameter uncertainties in the model-based control,an absolutely model free control method Partial Form Dynamic Linearization Based Model-Free Adaptive Sliding Mode Control is designed.Stability analysis shows that bounded-input bounded-output stability is guaranteed for the control system.Simulation and experiment results demonstrate the effectiveness of the proposed control algorithm.