Second order sliding mode control on task-space of a 6-DOF Stewart platform

In this paper, the second order sliding mode control strategy is applied on a 6-dof parallel manipulator, so-called Stewart platform. The advantages such as robustness and design simplicity of sliding mode control are the main reason that it was often used on robotic systems. However, the chattering phenomenon of conventional sliding mode control may cause unstability due to the practical implementations of the switching control. As a result of discontinuous control signal, the chattering phenomenon can be eliminated via designing a higher order control strategy. Once the switching signal is designed in higher order manifold, the real input will be smoothed because of the integration. The paper represents a robustness control method without chattering for Stewart platform which is a multi-input nonlinear system. The control performance of the second-order approach was compared to conventional sliding mode control in the simulation results.