Robust Control Of Robotic Systems. Uncertainty Study

This thesis deals with the following three topics with regard to the robotic systems with parametric (structure) and nonparametric uncertainties: 1. Deprived the kinematic and dynamical equations of a robot arm with 2-Link and four freedom degrees, and further generalized it to that with N-Link; 2. Proposed a class of robust control strategies for trajectory tracking of robot manipulators with uncertainties; 3. Based on variable structure control theory, Another kind of saturated robust control strategies was designed in this thesis. The development of robust control about the robotic systems with uncertainties and further study tendency can be found in the first chapter. At the same time, we give a brief introduction to the main work of the thesis. In chapter 2, the exact depriving process of the kinematic and dynamical equations was given, illustrating with a robot arm with 2-Link and four freedom degrees, then we generalized it to a robot system with n-degrees. From the depriving process, we can see that the dynamical model of the robot has the features of high nonlinear~. strong coupling and heavy complexity. In the end, we discussed several reasons influencing robot uncertainties, and obtained the dynamical model with uncertainties, preparing for further study in the following chapters. In chapter 3, firstly, with regard to a class of uncertain systems with sector nonlinear input, we presented a kind of continuous robust controller, which guaranteed globally exponential stability of the closed-loop systems, and tested it using an example; Then we applied it to the robot systems with parametric (structure) and nonparametric uncertainties, designed a class of controller which was robust to uncertainties as well as to input. It can be mostly suited to robotic systems with high speed, quick change of the parameter and strong requirement of the real time. Finally, a numeric example is given to demonstrate the effectiveness of the proposed method. In chapter 4, based on variable structure control theory, we firstly adopt the Stoline control law to the standard system, through introducing a kind of special saturated function and dealing with parametric and nonparametric uncertainties separately, A kind of saturated robust control strategies was obtained which was used for trajectory tracking manipulators with uncertainties. To robotic systems with relatively lo~v speed and slow change of the parameter, this method can perform excellently. In the end, we illustrated this point in a robot arm with 2-Link and four freedom degrees. At the end of the thesis, we give a overview of the whole contents of the thesis and also propose some further research problems.