Improving path accuracy of a crank-type 6-dof parallel mechanism by stiction compensation

The path accuracy of parallel mechanisms depends on both the mechanical design and the motion control algorithm that minimizes the following error. The PID control algorithm is not suitable for very precise motion control since it cannot compensate non-linear phenomena such as backlash and static friction or stiction. This work proposes a stiction compensation algorithm to improve path accuracy of a crank-type 6-dof parallel mechanism. The stiction has been modeled as a dead-zone and has been experimentally identified. The results were compared with those of the classical PID including velocity and acceleration feed forward.