Inverse dynamics and feedforward controllers for constrained flexible joint robots

A nonlinear feedback control based on inverse dynamics is proposed for robots with flexible joints during constrained motion task execution. Based on the constrained system formalism, the proposed control scheme achieves the simultaneous, independent control of both position and contact force at the robot end-effector. The method can be directly applied to robot control, or it can be used as the basis for developing other advanced control strategies. A feedforward controller is also considered. Issues related to the practical application of both proposed control algorithms, such as the use of predictors to eliminate the time delay of digital control and the design of robust controllers, are discussed. The results of extensive numerical simulation are used to show the effectiveness of the proposed controllers and to compare their performance