Kinematic Model and Analysis of an Actuation Redundant Parallel Robot With Higher Kinematic Pairs for Jaw Movement

A jaw movement robot that can simulate jaw movement and reaction forces in temporomandibular joints (TMJs) of a man will find many applications in dentistry, food science, and biomechanics. The TMJ is the most sophisticated joint in the human body, and its compound movements are not given sufficient consideration when a jaw robot is designed. Based on the biological finding about the mastication system and its motion characteristics, this paper proposes an actuation redundant parallel mechanism for the jaw movement robot and designs the actuation systems and models the TMJ in a higher pair kinematic joint. The prototype of the proposed jaw movement robot is presented, consisting of six prismatic-universal-spherical linkages for muscle groups of mastication and two point contacts for left and right TMJs. This robot has four degrees of freedom but is driven by six actuators. Each prismatic-universal-spherical linkage is made up of a rotary motor, a prismatic joint, a universal joint, and a spherical joint. The closed-form solution to the kinematics is found. This novel robot is evaluated by simulations of kinematics, workspace, and a chewing movement experiment.