PhanTOm project Dental haptics Training System



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haptic Devices


PHATOM Project aims to develop 20 low-end station and 3 to 4 advanced station. The main different between both stations is the haptic devices. Each Low-end station haptic device is based on modifying the Falcon [1] robot, which is a haptic joystick targeting the gaming market. The advanced system would be using the Omega [2] parallel robot by Force Dimension. The kinematics design of Falcon is based on Omega.
      1. Modification to Falcon


Figure 2 shows two setup for Falcon. The setup on the right is the standard Falcon, whereas the left setup, the Falcon is facing upwards and the mounting is specially made. Most of the dental operations generate downward force, having the Falcon facing upward allows all three motors act together to give higher force feedback and rigidly.
      1. Additional Angle Measurement


One of the most important issues with dental training is the angles and position of the hand piece such as drill and mirror. The Falcon has only 3 DOF measurement, which only gives 3D position (X,Y,Z). In order to obtain the angular measurement, additional 3 degrees measure



Figure 2. Right – Falcon standard setup, Left – Modify upward setup for better force response.

is needed. The 3 axis would need to be intercept with each other because of the force transition.



The first solution is to design a gimbal with 3 encoders (Figure 3). The 45 degrees offset is to avoid singularity problem with most dental position. This design suffers a major problem, which is the dentist finger resting position. Dental drilling finger resting position is around 5 to 8mm to the drill head.



Figure 3. First Design of Angle Mesurement Gimbal



Figure 4. 6 Encoders Base Angle Measurement Gimbal

Due to the limited distance and the importance of the finger resting positing, Encoders would have to be mounted at the back and the gimbal would require to be much smaller. This initial prototype is shown in figure 4. This design involve the angle measurement is taken from the back of the drill instead of the front. This design would require 6 encoders. Three of the encoders would calculate out the position and the other three would be the angle. These angles are matched with the Falcon.


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