Control of rapid closing motion of a robot jaw using nonlinear spring mechanism

Describes mathematical models that simulate the nonlinearity of the human muscle, and the results of a real food chewing experiment by a mastication robot. When the lower jaw rapidly closes, it may come in hard contact with the upper jaw if the food is a crushable one. To clarify the mechanism of rapid jaw motion, the authors focused on the nonlinearity of the human muscle that is known in the field of the physiology or biomechanisms. The authors propose a feasible mathematical model for the muscle and its nonlinearity. A nonlinear spring mechanism is then designed based on the mathematical model. As a result of chewing experiment, the authors confirmed control of the rapid closing motion of the robot jaw using the nonlinear spring mechanism. This work was done as part of the "Humanoid Project" at HUREL (Humanoid Research Laboratory).