Positional Error Estimation of the Parallel Manipulator for Control Application

Parallel manipulator (PM) become popular in industrial application over serial manipulator owing to the higher accuracy, fast response and rigidity. In the present study electrohydraulic two degree of freedom (2DOF) PM is considered for study the control performance. Apart from measurement and sensor error parallel manipulator may experienced structural error, which may cause of joint clearance. Lab. scale 2DOF PM has been considered structural error analysis due to joint clearance. Further, a model free self-tuning fuzzy-PID-bias (F-PID-B) controller has been developed for control of the orientation of the top platform of PM. The controller performance has been studied for combined sinusoidal heave and pitch demand. The robustness of the controller has been tested under various demand and different external load. F-PID-B controller has shown the ability to handle external load disturbances with measurement uncertainty and system nonlinearity using a low cost proportional valve controlled hydraulically actuated PM.