Golf Prosthesis Final Design Report (P8)
Description of Final Designs
There are two final designs, the golf sleeve and the golf cuff sleeve. Both of which make it easier for a double arm amputee to securely grip the club while using their everyday prosthetic hooks. The designs have different ways to grip the club which will accommodate any preference the user has.
Adaptive Golf Sleeve
The adaptive golf sleeve is a modified design based on the TRS Grip. The TRS Grip is a terminal device for single arm amputees who want to play golf. The general concept of the golf sleeve is similar to the TRS Grip. Unlike the TRS Grip the Golf Sleeve will be made via the UV Resin rapid prototype machine. Originally we wanted to manufacture our device using an injection mold. This would allow us to test different materials from a single mold. After several failed attempts we decided to pursue using the UV resin rapid prototype machine. The UV Resin isn’t as flexible as polyurethane, but the availability of its use allows us to make numerous iterations.
The golf sleeve is applied to a golf shaft just like the TRS Grip. The user will slide the grip up the shaft starting from the lower end where the shaft diameter is smaller. A ring has been added to the top of the golf sleeve allowing the user to pull the sleeve up the shaft of the club to the desired position.
The main focus of the golf sleeve is to incorporate the use of hooks that bilateral amputee’s use, located at the ends of their prosthetic arms. In Figure 22 you can see exactly where each hook is applied onto the sleeve once it has been secured to the shaft of a club.
In order to simulate an actual golf grip the hook inserts were designed so that the user has to place their left arm above their right arm just like an actual right handed golf grip. If the bilateral amputee is left handed then an alternate device can be made to suit their preference. In order to give the user more security while gripping the club, slots were cut from underneath the sleeve where the bottom of the hooks can be placed. The slots can be seen in Figure 23.
The golf cuff was designed to provide a stronger and more secure grip on the club. This originated from Jim Taylor’s golf prosthetic arms. He wraps one of his hooks in several layers of tape which increases the area of the contact point. If a bilateral amputee just used their hooks to grip the golf club, there would be a small contact point between the hooks and the grip creating a large concentrated force on the shaft. John Lawson, an upper extremity bilateral amputee, plays golf with special shafts that were double wrapped so that the shaft does not snap in half during the golf swing.
The golf cuff increases the area of that contact point so that the user can have more control over the golf club. The force from the hooks is now a distributed force along the end of the shaft, which minimizes the likelihood of the shaft snapping. The design was originally going to be two separate cuffs that attach to the club, but there were problems with the inside taper of the cuffs fitting snugly on the golf shaft. To fix this problem, the same taper for the golf sleeve was incorporated into this design to provide a more secure connection between the grip and the device. The final prototype was made using the UV resin rapid prototype machine at Cal Poly. This plastic is strong enough for the application but it will wear quickly over time. Ideally the device will be made out of polyurethane or some other type of rubber.
A bilateral amputee can simply put the device on the club by inserting their hook in the pull ring and then pulling the sleeve up the grip until it tightly fits. The slots in the device were designed so that the hooks fit perfectly to allow for a secure grip on the club. Once the hooks are inserted in the slots, the hooks will not move unless the user opens up their hooks during the golf swing. This device is shown in Figures 24 and Figure 25.
Before using this device it is important that the bilateral amputee has full control over the club. If they feel uncomfortable swinging with the device they can wrap tape, bungee cord or Velcro around the hooks so that the club will not come loose during the golf swing.