A novel model manipulation of elastic-joint robots for control purposes

This paper presents a new method to control elastic-joint robots. Models that include electrical and mechanical parts of actuator dynamics, together with joint elasticity are considered. A novel nonlinear coordinate transformation is introduced. It is possible after the transformation to exactly linearize the model by the direct computation of the transformed nonlinearities or, for the first time, by the use of an observer that estimates the unmeasured states and nonlinearities. Tracking and disturbance rejection requirements can be met in the design of the outer loop. Simulation results are given.