The Three Cable Haptic Interface (TCHI) prototype built by Williams et. al (2006) is improved by selecting and installing appropriate motors and designing cable reels which together successfully provided the proper amount of force for the intended application.
Simulation was performed which showed that the required cable tension force rises almost linearly with frame size, but rises exponentially as the distance from the base plane (Y distance) decreases. Furthermore, it was determined from simulation that the required cable tension can be significantly lessened if the device is configured in such a
way as to limited the workspace to approximately 6 cm from the top and sides and 13 cm from the imaginary diagonal which spans from top right motor to bottom left.
The new TCHI prototype is theoretically able to exert 31N of continuous force on the user, a 10 fold improvement over the PHANToM 3.0 and has a nominal position resolution of 0.004mm, a 5 fold improvement over the PHANToM 3.0. The new TCHI
prototype is also superior to the PHANToM 3.0 in terms of maximum exertable force, stiffness, cost, and workspace if configured properly.