Design and constant force control of a parallel polishing machine

In order to improve the low efficiency, poor product consistency and cruel working environment of current manual polishing method, a parallel polishing machine is presented. First, based on the freeform surface polishing requirement, a scheme of the automatic polishing machine is proposed, which includes a five-DOF parallel manipulator, a single DOF rotary table and a linear motion platform with a force feedback system. Next, a polishing force control model of the linear motion platform is established. Fractional order PIλDμ control method is introduced to achieve force-displacement hybrid control. Finally, the parallel polishing machine is developed and a constant force polishing experiment is conducted. The experimental results display that parallel polishing machine is capable of improving the roughness of the surface of the manufactured part from level 9 precision to level 11 precision.