Golf Prosthesis Final Design Report (P14)
The idea of the Pre-set Wrist came from the same need to find a way for a double arm amputee to hinge their wrists during the golf swing in order to maximize the force at impact with the golf ball and the golf club face. This is accomplished in the Pre-set Wrist design by hinging the wrist ahead of time prior to starting the backswing. This idea was derived from a golf drill that many instructors use to teach amateurs and professionals how to feel the proper wrist hinge during the take away and backswing.
The Pre-set Wrist design is made from mostly aluminum components, where the lever and TRS grip are made from a polyurethane material and the ball and sock joint is made from stainless steel. The slotted wrist attaches directly to the butt end of the golf club. The TRS grip attaches in the same manor discussed in the slotted wrist design, and secures the club through friction generated between the TRS grip and golf grip. In this design a slot and pin mechanism is used, with a designed lock and unlocking feature that hinges the wrist into the appropriate position with the application of an upward applied force (Fig. 37).
The wrist will stay hinged in this position until an equal but opposite downward force is applied to the locking mechanism. This force will be exerted on the down swing by the extension of the right arm, unhinging and unlocking the wrist from its pre-set position just prior to impact, allowing the club to strike the golf ball. A 3-D model of this design is located in Appendix E.
Magnetic Pre-set Wrist
Figures 38 and 39 below show the magnetic wrist design. This design uses a magnet to hinge and release the wrists during the golf swing. There will be a compartment located on the prosthetic that will have a microprocessor and an accelerometer that controls the strength of the magnet. The accelerometer will detect the accelerations produced during the golf swing. When the club accelerates, current will be sent through the magnet, making it magnetize. The more current that goes through the magnet, the stronger it will be.
This will allow the wrists to hinge as the back swing is made. When the swing starts to return to the neutral position, the magnet will release the club and then another magnet will catch the club on the follow through. This design will require a lot of analysis of a golfer’s swing to figure out the placement of the magnets and the strength of the magnets. The grips on all shafts will have to be removed and altered so that the shaft can be directly attached to a ball and socket joint on the prosthetic.
The bevel gear design idea originated from the golf swing robot arm, also known as the Iron Byron, seen below in Figure 41. The basic concept of the Iron Byron involves a bevel gear system that is attached to a golf club. The arm is powered by a motor that initiates rotation for the backswing. During the backswing the club is able to rotate laterally and radially due to the freedom the bevel gear allows. The club locks in position at the top of the backswing due to a lever that is caught by a hook under the robotic arm. Once the club starts the downswing a solenoid releases the hook’s grip allowing the club to swing completely through the ball.
The bevel gear design idea for the golf prosthesis uses the basic concepts from the Iron Byron. The main difference between the two is that the Iron Byron simulates both arms swinging a golf club while the bevel gear design is only designed for one arm. The bevel gear system is attached to the end of the right arm which allows rotation in the backswing. The bevel gear system attaches to the grip of the golf club using a TRS Eagle grip. Similarly, the left arm uses a TRS Eagle Golf TD grip that attaches to the grip of the golf club. Since the TRS grips are made of polyurethane they have a substantial amount of flexibility that assists in the rotation of the golf club