DYNAMIC CHARACTERISTICS OF CONSTRAINED MANIPULATORS FOR CONTACT FORCECONTROL DESIGN

The authors present the results of eigenstructure analyses of the dyna mics of several manipulator and environment configurations and discuss the implications for successful force controller design. The manipula tor configurations considered include single rigid link, single flexib le link, two rigid links, and two flexible links. In all cases, the ti p of the manipulator is in contact with a deformable environment. Part icular emphasis is placed on the interaction between the structural st iffness of the manipulator link and the stiffnesses of the contacting regions of the manipulator tip and the environment. it is shown that, for given link parameters, this interaction results in distinct change s in the modal structure of the manipulator/environment system as the effective contact stiffness increases. In particular the contact force response is dominated by a single mode for a given effective contact stiffness, whereas the control inputs excite all modes except those as sociated with the contact region vibration. The changes in the modal s tructure of the manipulator/environment system predicted by the eigens tructure analysis are verified by experiment for the single flexible l ink configuration.