Prototype Design And Experimental Research Of A Robot For Jaw Movement

In human physiological activity, the jaw system plays important functions in chewing food, expressing language and controlling expression. Using the temporomandibular joint(TMJ) as the connection joints, the human mandible driven by the muscles performs the functional motion including opening and closing motion, front and back motion, sideways motion, etc. A robot that simulates the jaw movement is one kind of engineering science encompassing mechanism, biomechanics, mechatronics and motion control. And the research results have a wide application prospect, such as abration test of denture material, fatigue life test of denture and medical teaching, etc.Based on the redundant characteristic of the mandible system and the mechanical bionic principles, the prototype of redundant parallel mechanism for jaw movement is presented, consisting of6PUS linkages for muscle groups of mastication and two point contacts for left and right TMJ(6PUS-2HP) to reproduce human jaw motion.First, this paper focuses on the background of this project as well as its research importance, and then introduces the research status of the jaw movement robot and the redundant parallel mechanism respectively. In addition, the main work and research content in this paper is proposed.Secondly, based on the mechanism of human jaw movement, the bionic data of TMJ and the design parameters of the muscles are collected. In addition to this, the insertion positions to mandibular of the masster, temporalis, lateral pterygoid and the length of the muscles action line are determined, and the mandibular fossa curve is fitted.Then according to the parameters of the bionic design, the6PUS-2HP mechanism is designed. In addition, the kinematics model of the6PUS mechanism with six degrees of freedom is established. Because the kinematics inverse solution and the trajectory planning for the6PUS-2HP mechanism with four degrees of freedom this paper proposed are based on the traditional6PUS mechanism with six degrees of freedom, the kinematics model of the6PUS mechanism is particularly important for the robot design of this paper.Next, using the virtual simulation software Adams, the kinematics analysis of the6PUS-2HP for the jaw movement robot is simulated. And then, According to the motion range of the key parts, the models of the key parts are selected and the mechanical structure of the robot prototype is designed in detail. Using the programmable controller PEC6A00to realize the motion control for the jaw movement robot, this paper designs the hardware and software of the control system for the robot detailedly.After that, using the Adams to simulate the movement of the jaw movement robot with four degrees of freedom and six actuators, the motion trajectory of the robot is planned. Providing that the both sides of TMJ condyle in constraint always contact with the madibular fossa surface, the drive pulse of the six motors is solved.Finally, this paper conducts the experimental study of functional motion on the prototype of the jaw movement robot. The opening and closing motion, front and back motion, and sideways motion are imitated respectively. The results proved that this jaw movement robot can combine the mandible motion with the TMJ motion better, and can realize the human mandible motion, especially the forms of the TMJ motion.