Closed-form solution of the direct kinematics of the 6–3 type Stewart Platform using one extra sensor

A procedure for the determination of the actual configuration of the 6–3 type Stewart Platform is presented. The procedure makes use of one extra sensor in addition to the six that provide the mechanism leg lengths. The use of one extra sensor suitably located on the mechanism allows the direct position analysis to be solved in closed form and makes it possible to obtain a one-to-one correspondence between the sensor measurements and the configuration of the mechanism in almost the entire workspace. Particular configurations where the correspondence is not one-to-one are outlined and criteria to identify them given. Sensitivity to sensor measurement errors is investigated.Paper presented at the 12th Italian Congress on Theoretical and Applied Mechanics AIMETA 1995, Napoli, 3–6 October 1995