Design, modeling and control of a system for dynamic measuring of leg length discrepancy

This paper presents a system for dynamic measuring of leg length discrepancy (LLD). The system consists of two 3-RPS parallel manipulators with three degrees of freedom. Parallel manipulators have force sensors that determine the patient's center of gravity (COG) displacement. By changing the height of the moving platform of the parallel manipulator, COG returns in its expected position. The difference between the heights of moving platforms equals the amount of LLD. Inverse kinematics of the 3-RPS parallel manipulator was performed. A virtual simulation system was made and tested in MATLAB/Simulink. The paper presents simulation results of the system operation.