Contact kinematics of spatial higher kinematic pairs of a masticatory robot

The temporomandibular joint (TMJ) is a complex bilateral articulation, and its movements are a combination of hinge movement and gliding movement guided by its articular surfaces. A masticatory robot with higher kinematic pairs (HKPs) simulating TMJ behavior is introduced. Kinematic equations of the HKPs are derived based on three-dimensional kinematics of rigid bodies and differential geometry. Position, velocity and acceleration of the contact points are analyzed according to the characteristics that the condyle movement involves rotation and translation simultaneously. Given a target trajectory, the position of contact point, velocity and acceleration relative to articular surface of fossa are obtained by simulation based on the contact kinematics of the HKPs. The result provides a useful tool for studying kinematics behavior of human TMJs.