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Robotic Temporomandibular Joint Project
The Australian Jaw Joint Project

Authors:
Carl Bowey, David Burgess

Supervisor:
Mr Antoni Blazewicz

Institution:
University of Adelaide
Mechanical Engineering

Client:
Australian Jaw Joint Project

The Temporomandibular joint, or more commonly known as the jaw, is a joint that's workings are poorly understood. Unlike other joints it cannot be easily modeled for interrogation. It has been a long held belief in the dental an d medical communities that incorrect loading of this joint may encourage development of temporomandibular disease. Mal joint loading can be caused by such things as Nocturnal Bruxism (night grinding) which has been reported to produce over 4100kpa (600psi) at the teeth. Static forces within muscles can be calculated from bite force although muscle share ratio can only be estimated. Dynamic forces in the muscles responsible for movement have yet to be established. Methods used to investigate the theory of incorrect loading have not had a marked success.

Three anatomical chewing machines have been developed and have performed rudimentary chewing motion and not much else. The task undertaken by this team has been to develop a robotic jaw that can be programmed through Gait Analysis to mimic true joint movement and also have the ability to return dynamic muscular forces to gain a better understanding of internal workings of the joint.

The Auckland University biomechanics department has a team lead by Andrew Pullen uses Gait analysis of the human jaw with the intention to produce CFD modeling of masticulation. They have kindly supplied us with the Gait sample used to program the RTMJ.

The Dynamixel modules have been the key component in the success of this project. They provide the power and feedback the robot requires. The intricacy of the mechanism requires the 9 Dynamixel DX-113's to update position at the same rate as the gait sample, 100Hz. This rate does challenge the serial communication speed. The DX-113's come in just under the 200N specification of the two strongest muscles. These can be replaced with the DX-117 if problems arise.

For further information please contact David Burgess: