Abstract: Subsystems of force feedback gripper system are analyzed.The mathematical models of the position/force conversion,detection,motor-drive and control subsystems are established.Furthermore,the piecewise state-space model of whole feedback system with saturation nonlinearity is proposed.Using the actual response of the system,the parameters of this nonlinear model are obtained via the least squares method and the genetic algorithm.The response results of the simulation system based on the proposed model,the simulation system based on the second order linear simplified model and the actual system,are compared.The effectiveness of the model and the tuning method of its parameters are confirmed.