Design and workspace analysis of a new endoscopic parallel manipulator

This paper describes the development of a dexterous endoscopic parallel manipulator for laparoscopic surgery using rigid mechanism. Based on the concept of virtual chain and screw theory, previous endoscopic parallel manipulators are deeply investigated to put their synthesis in a systematic rigorous procedure that helps in proposing the new 4-DOF endoscopic parallel manipulator. The inverse and forward kinematics solutions are derived analytically and numerically respectively. The known problem of limited bending angles was solved in the proposed manipulator as it can reach ± 90° in any direction. The proposed manipulator consists of four legs; two legs are 2-PUU (each leg consists of one active prismatic joint and two passive hook joints); the other two legs are 2-PUS (each leg consists of one active prismatic join, one passive hook joint and one passive spherical joint). Four linear motors are used to drive the mechanism. The performance is investigated through simulation by ADAMS software. Dexterous workspace is obtained and this validates the advantageous bending capability of the new proposed manipulator compared to previous ones.