PROJECT TITLE :

Planning Wrench-Feasible Motions for Cable-Driven Hexapods

ABSTRACT:

Motion methods of cable-driven hexapods must fastidiously be planned to make sure that the lengths and tensions of all cables stay inside acceptable limits, for a given wrench applied to the platform. The cables cannot go slack-to keep the control of the robot-nor excessively tight-to stop cable breakage-even within the presence of bounded perturbations of the wrench. This paper proposes a path-coming up with methodology that accommodates such constraints simultaneously. Given 2 configurations of the robot, the method attempts to attach them through a path that, at any point, permits the cables to counteract any wrench lying in an exceedingly predefined uncertainty region. The configuration space, or C-space for short, is placed in correspondence with a sleek manifold, which facilitates the definition of a continuation strategy to look this area systematically from one configuration, until the second configuration is found, or path nonexistence is proved by exhaustion of the search. The force Jacobian is full rank everywhere on the C-house, which implies that the computed paths can naturally avoid crossing the forward singularity locus of the robot. The adjustment of tension limits, moreover, permits to keep up a meaningful clearance relative to such locus. The approach is applicable to compute paths subject to geometric constraints on the platform create or to synthesize free-flying motions in the total half dozen-D C-house. Experiments illustrate the performance of the method in an exceedingly real prototype.