The Inteligent Force/Position Control For X-Y Positioning Table

The end-effector of a X-Y positioning table is required to keep precise postion tracking and keep a contact force along the outward normal of the constraint surface in tasks such as deburring and grinding. Base on the relevant literature at home and abroad, we did some researches on force control for X-Y table. The main research of this paper is concluded as follows.First, a kind of force control strategy for X-Y table is proposed on the premise that the position controller is not changed, namely, the outer loop is force control loop. The reference position is modified according to the force error so that the expected contact force between the X-Y table and the environment can be achieved. In force control loop, unknown environments is identificated by a modified Elman neural network online. The prior knowledge of the environment is not required. This method can compensate the errors of environment and guarantees the robustness of force control. Simulation results show that this control strategy is effective.Second, a kind of hypbrid force/position controller based on RBF neural network is presented for constrained X-Y positioning table. PD controler is used in position control. In force control, the RBF neural network is applied to learning the upper bound of system's uncertainties and proportion controller strengthens the completeness of this control strategy. The results of numerical simulation demonstrate the stability and robustness of the system. The precision and adaptability is improved effectively under the proposed control strategy.Finally, an impedance control algorithm is presented in force control for X-Y positioning table. The key of this algorithm is to select the proper impedance parameters. So the parameters of impedance model are adjusted fuzzily real-time according to the change of force, positon and volocity of X-Y table. This method can reduce disturbance in constrained motion and can improve the global force control performance.