Fuzzy impedance and force control of a Stewart platform

A new, simple, and effective control method is proposed for the position-based impedance and force control of a Stewart platform (SP). The control approach can be divided into 3 parts, namely position control in free space, impedance control in contact, and force control. An impedance filter is developed to achieve the desired behavior between the position and force. The gain of the filter is modified by a fuzzy logic proportional-integral-derivative controller. Kinematic and dynamic models of the SP are simulated in a MATLAB/Simulink environment. Several realtime experiments are conducted with the SP developed in our laboratory. The results of the simulations and real-time experiments are compared to show the effectiveness of the proposed method. The experimental results demonstrate that the position control of the SP in Cartesian space is achieved at up to precision of 0.5 ^ m and 0.43 in linear and rotational motions, respectively, and force control of the SP is obtained successfully with a range of between 1 N and 50 N. Steady-state force errors are also eliminated with an intelligent integrator.