Mechanical

For the mechanical aspects of the hand, everything was done with CAD through Solidworks and printed with PLA filament.

What We Accomplished

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Complete with five fingers, with finger pins and dental dams to bend
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Pulley system to pull string, folding fingers

Final Cyberflex Hand

Final CAD Hand Model

It has multiple joints at the fingers that either extend or collapse inwards. For the fingers, there is a tension/pulley system where each finger is connected to a string or cable, which when pulled by motors, will pull the finger inwards. The palm also has built in shells for the motors. A stand for the hand to be upright also is complete with a wrist section, so it can turn left/right and up/down.

Fingers

The fingers are made up of three different parts: the finger pin (top left), fingertip (bottom left), and phalanx. The tip is the top and the phalanx is the middle, whereas the pin, one of the two joints, secures them both in place. The fingers are all mounted on one large shoulder bolt which acts as the second joint for all the fingers. These two joints allow the finger to bend–the pulley system winds some string channeled through the fingers up to curl them downwards while two sets of dental bands extending over each of the joints allow the finger to extend back up to its starting position once the string is no longer in tension.

Palm and Wrists

Inside the main palm, there are casings for five motors to fit inside snugly that control the fingers and thumb, one of which holds a motor that rotates the thumb palm around its shaft axis. The thumb palm contains yet another motor to control the thumb (finger portion) itself. Several portions of the covers of the two palms are extruded outwards to press gently onto all the motors and their casings to ensure that none of the motors have room to wiggle out if the friction between the motors and their casings proves to not be enough to hold them in place. Again, these covers are screwed on with the help of heat set inserts mounted on towers flush with the rim of the palm. The wrists are mounted onto the base of the main palm with bolts and consist of 3 sections–the first of which acts as a simple attachment. The middle section of the wrist contains casings holding two motors controlling the vertical motion of the wrist. The motor shafts connect to the first wrist section to rotate it. The final wrist section contains the largest and strongest motor controlling the horizontal movement of the wrist. This motor rotates the above wrist section and the entirety of the hand along with it.

Matlab Code for Wrist Mechanisms

The code above is to check the wrist mechanisms how strong the motors need to be to turn left and right.

The code above is to check the wrist mechanisms how strong the motors need to be to turn up and down.