Superiority of finite time SDRE and non-singular terminal SMC controller for n-DOF manipulators

In this paper, a global non-singular terminal sliding mode (NTSM) controller is presented for a class of nonlinear dynamical systems with uncertainty parameters and external disturbances. In addition, it investigates finite-time state-dependent Riccati equation (FTSDRE) for time-varying systems with state and control nonlinearities. A finite-time constraint that has been imposed on the equation will consequently changes it to a differential equation and also strongly decreases state error and operation time. These two methods are both nonlinear with a systematic structure that enable user control systems for a wide range of applications, explicitly in control of manipulators and robots. Finite time state-dependent Riccati equation (FTSDRE) is one of the optimal nonlinear controllers, in which time can be given as input value. On the other hand, sliding mode control systems are robust to uncertainties and disturbance and are able to direct the states to desire portion perfectly. Also, to eliminate the effect of chattering which is a drawback to siding mode controller, hyperbolic tangent function is used. The formulation of both systems are presented and then a model for a five-DOF arm, ATLAS II ROBOT, are designed and then simulated for both methods and only then they are illustrated and discussed.