Impact control of a single-link robot striking different environments: Theoretical and experimental investigation

The paper deals with the impact control of a single-link rigid robot, striking different environments, i.e., having different elastic/plastic characteristics. The control goal is bringing the link in a stable contact with different external environments, reproducing elastic, rigid, or quasi-rigid impact conditions, and guaranteeing a desired value for the steady-state position of the link, compatible with the contact. The proposed control scheme, for which neither the impact time detection, nor force measurements are required, employs a reduced-order observer for the estimation of the impact-induced forces, to be compensated by the feedback control law. It is analytically shown that the complete knowledge of the parameters of the link dynamic model is not strictly necessary for the implementation of the proposed control scheme, whose validity is proven also experimentally by means of a simple test-bed, reproducing the considered case. The results of the carried out tests are reported and discussed in the paper, and compared with those relative to the application of a simple PD control law. © 2000 EUCA.