A comparative study on SMC, OSMC and SDRE for robot control

In this paper, a comparative study is conducted to investigate the capability of three nonlinear methods in controlling manipulators. The sliding mode control (SMC) as a nonlinear method with robust nature and state-dependent Riccati equation (SDRE) as a nonlinear suboptimal technique are performed to illustrate the effectiveness of robustness and optimality combination. The optimal sliding mode control (OSMC) has both mentioned essence. The OSMC benefits from linear quadratic regulator (LQR) to define its gains. This reduces the magnitude of input signals and eliminates the chattering phenomenon. The end-effector error, norm of control inputs and dynamic load carrying capacity (DLCC) are computed as some important criteria of industrial robots to assess the controllers. Simulation results showed that the OSMC method, in addition to control input reduction has also the robustness properties and it can be considered as a suitable approach in this area.