Contact force control for 2 DOF, manipulators based on iterative learning operation

T. Suzuki et al. (1992) previously proposed a contact force control method with a learning method for single degree-of-freedom manipulators. The learning control was based on an iterative operation, and was one of the feedforward controls which do not need precise values of the system parameters. The authors expand that learning method to a method for two-degree-of-freedom manipulators. Some problems exist in the case of learning for a normal and a tangential component of the approach velocity. Therefore, a new learning algorithm is presented keeping the ratio between a normal and a tangential component to a constant value. The relationship between the approach path and learning robustness is studied from the point of view of system control theory. It is clarified that an approach path exists which substantially degrades the learning robustness. Some simulation results to verify the effectiveness of the proposed method are presented