Direct Singularity Avoidance Strategy for the Hexa Parallel Robot

Machine supervision on parallel robots demand a powerful online singularity loci prediction. To detect the entrance of the end-effector on direct kinematic singularities that constrain the internal workspace is not trivial for parallel robots with five or six degrees of freedom. This paper presents a strategy to safely drive a Hexa parallel robot out of direct singularity regions based an index of power. The used index indicates the entrance of the Hexa parallel robot, considering its joint limits, to all its direct kinematic singularities. This index is calculated through the power inspired measure. The applied procedure uses screw theory to represent movements and actions in the robot. The use of this index allows the development of the presented strategy to safely drive the robot out of regions near singularities. This procedure is experimentaly verified on a Hexa parallel robot.