2010 Volume 20 Pages 157-169
In order to deeply understand the human jaw-movement mechanism, we have been developing an autonomous jaw-movement simulator, JSN, with a life-like design in anatomical structure as well as in control scheme. In this study, we equipped JSN/3A with the following three functions: 1) periodontal masseteric reflex, 2) detection of food elasticity and 3) feedforward control advancing the onset of masseter and internal-pterygoid activities after food detection, all of which are believed to be effective for efficient mastication. Simulation results suggested that the initial inhibitory phase of periodontal masseteric reflex has a role of reducing a sharp rise of the bite force immediately after tooth contact, whereas the following excitatory phase has a role of increasing the bite force. Food stiffness could be estimated by using two different sensory data of the wire length of the anterior temporalis actuator and the bite force applied to the upper first molar. The feedforward control was efficient to simulate a natural and effective bite driven primarily by masseter and internal pterygoid muscles.
