Redundancy in Parallel Robots: A Case Study of Kinematics of a Redundantly Actuated Parallel Chewing Robot

The term “redundancy” is associated with various concepts in the literature of parallel robots. The differences between these concepts can be confusing for the researchers. However, deep understanding of these concepts and their advantages and disadvantages allow for efficient synthesis and application of the parallel robots. In this paper, for better understanding of the differences between the concepts of redundancy in parallel robots, each concept is introduced and presented in the structure of a spatial parallel robot, moreover, the advantages and disadvantages of each concept are discussed. The actuation redundancy, in which the parallel robot is actuated by more actuators than required for controlling the degrees of freedom of the end-effector of the robot, is one of these concepts. Using redundant actuators in parallel robots, owing to bringing a variety of advantages for the robot, has become an emerging research topic. Adding kinematic constraints to the structure of a non-redundant parallel robot as a way to realize the actuation redundancy is studied in a redundantly actuated parallel chewing robot with two point contact higher kinematic pairs. Spatial chewing trajectory of a human subject is captured by a novel motion capture system and the captured trajectory is used as the input data for analytical study of the kinematics of the redundantly actuated parallel chewing robot. Finally, diverse applications of the mandibular motion capturing and the redundantly actuated parallel chewing robot in dentistry and industry are discussed.