Practical design of VSS controller using balance condition--Robotic application

VSS controller is suited for robotic arms where the robust performances in the presence of parametric variations and disturbances are most important. The practical design of such robust VSS controller is discussed in this paper. The significant issue in the design of VSS is to avoid the chattering caused by the switched input. This problem is solved by introducing the continuous control input instead of switched input. The practical design of such control is obtained by using "Balance Condition". The "Balance Condition" is derived from the careful consideration on the bandwidth of plant dynamics and VSS controller, and gives many benefits in applications of VSS controller to actual systems. This paper shows the validity of balance condition in the robotic arm control. Simulations and experimental results using a position servo system (one degree of freedom robotic arm) are discussed from the practical point of view of robust control. In order to investigate multi-joint cases, simulations with a two-linkage robot arm are provided.