Research of iterative learning control for a novel 2-DOF planar parallel robot

This paper proposes a novel 2-DOF high-speed/high-accuracy robotic system: two permanent linear motors drive a planar parallel mechanism. Analysis of mechanism dynamical model verifies that load variation is violent. Due to the direct-drive principle of a linear motor, the load disturbance can have a significant effect on motor performance. For this purpose, designs a zero phase error iterative learning feedforward controller and feedback controller. At last, experiment results validate that using a causal zero phase error approach, high-performance motion system is obtained. The maximum acceleration is 8 m/s², the maximum speed is 0.5 m/s and the zero phase ILC design has converged after 5 steps to an average error 0.004 mm.