Forward and Inverse Position Kinematics for the RRSSR Parallel Robot With Hardware Validation

This paper presents forward and inverse position kinematics equations and analytical solutions for the 2-dof RRSSR Parallel Robot. Two ground-mounted perpendicular offset revolute (R) joints are actuated via servomotors, and the single-loop parallel robot consists of passive R-S-S (revolute-spherical-spherical) joints in between the active joints. A study of the multiple solutions in each case is presented, including means to select the appropriate solutions. This rigid-link parallel robot forms the hip joints of the Ohio University RoboCat walking quadruped. The methods of this paper are suitable to assist in design, simulation, control, and gait selection for the quadruped. RoboCat hardware has been built and used to help validate the examples and results of this paper.