Influence of the manipulator dynamic properties on the design of a force-position controller

Assuming a pure elastic environment and a contact force acting only along the normal direction to the undeformed environment surface, the influence of the working parameters of a 2 DOF planar manipulator to the dynamic behaviour of the system is well investigated. The proposed analysis suggests the implementation of a hybrid force-position control and the design of a nonlinear state feedback controller in which the gains change as a function of both the manipulator and the environment configurations. In this way a continuous gain scheduling is carried out: depending on the movement and on the environment interaction each gain is evaluated from a continuous polynomial expression that interpolates the offline evaluation of them, defined with the pole-placement method, for a set of discrete possible working conditions in a linearized manipulator model.