Performance Analysis And Parameter Optimization Of A Jaw Moment Parallel Robot

The human jaw system plays an important role in many physiological activities such as controlling expressions, chewing food, speaking, etc. A jaw movement robot refers to a kind of bionic robot with the ability of imitating the human jaw movement, which is mainly used in jaw system rehabilitation training, food texture assessing, dental materials testing and many other fields. With the maturing of bionics and robotics, a jaw movement robot tends to be further anthropomorphic. So it is necessary to pay close attention to the practical working performance of the mechanism based on bionics.After the review of researches on jaw movement robots and parallel mechanisms, analyses of working performance and an optimization of structural parameters for a jaw movement robot based on a6-PUS parallel mechanism were carried out according to the research methods of parallel mechanisms, which took the application requirements of the robot into account.First of all, the research background and significance of the subject was outlined. Current researches on jaw movement robots were introduced and the research methods of parallel mechanisms were summarized. The main content of this paper was put forward.Secondly, the basic information about the jaw movement parallel robot was introduced briefly. The kinematics model was established and the inverse position solution of the sliders was carried out. The expressions of the inverse velocity solution and the velocity jacobian matrix were carried out. The dynamic model was established based on the Lagrange’s equation of the second kind.Thirdly, an analysis of the main influencing factors on the working space was carried out and the mathematical models for the constraints of the working space were established. A program for solving the working space was designed in MATLAB. The working spaces of three given postures of the moveable platform were solved out respectively. An approximate trajectory of a symmetry mouth movement was put forward and the range which the robot could reach was discussed.Fourthly, three kinds of working condition which may occur in practical application were defined. Kinematics and Dynamics analyses were carried out under the simulated trajectory and loading conditions according to the physiological parameters. Simulation results showed that the kinematic performance of the robot could meet the demands of practical application, but the driving forces under the given working conditions were high, so it was necessary to improve the dynamic performance of the robot.Finally, an optimization of the structural parameters was carried out in order to decrease the high driving forces shown in the simulation results. Nine structural parameters were taken as design variables. The influence of each design variable on the driving forces was discussed. Three design variables which played important roles in decreasing the driving forces were selected to be optimized. Comprehensive simulation analyses were carried out on the optimized mechanism. Simulation results showed that the optimization scheme was feasible and effective. The driving forces of the sliders decreased obviously under the same working condition, which meant that the dynamic performance of the robot was improved.