The Light Sabre

Designers: Matt Lerner, Robyn Schwartzman, Henry Shen

Client Coordinator: Jeff Kallio, Coach, Mid-South Fencers’ Club

Supervising Professors: Kevin Caves and Richard Goldberg

INTRODUCTION

Wheelchair fencing is a recognized Paralympic sport that was first introduced at the 1960 Games in Rome. Competitors’ wheelchairs are secured to a stationary frame on the ground, allowing for upper body movement of the competitor but no back and forth movement of the wheelchair like that in standing fencing.  The governing body of wheelchair fencing is the International Wheelchair and Amputee Sports Foundation (IWAS); IWAS determines the rules for competition with all three weapons, in addition to regulating the standards for equipment.

Our client, Amy, has Osteogenesis Imperfecta, commonly known as “brittle bone disease,” which is a congenital disorder that affects the strength of the bones in the body.  She uses a wheelchair for mobility but can lean side to side and rotate her upper body from the seated position.  Though fencing frames are available for purchase, Amy currently trains without one because existing models are less than ideal for use in a practice setting.  Many of these platforms are made of heavy materials that restrict portability, which does not allow for transport between the gym and local competitions.  On the other hand, models that are portable are either unstable or are cost-prohibitive, particularly because our client is the only wheelchair fencer at her gym.  Furthermore, current models do not allow the competitor to independently secure herself into the frame and have been shown to wear down with prolonged use.

We developed a fencing frame that will allow Amy to practice with other fencers (both able-bodied and those with disabilities) in a safe manner.  The platform adheres to the specifications outlined in the IWAS manual on wheelchair fencing and takes into consideration the requests of the client and her coaches.  The novel design includes several features not currently included in fencing frames, such as allowing for independent tie-down by competitors, use by able-bodied fencers, and easy transport and set-up by members of the gym.  The design also avoids the mechanical issues found in current models by reinforcing problem areas or changing them entirely to limit the applied strain.

Figure 1: Photo of the Light Saber Wheelchair Fencing Platform

SUMMARY OF IMPACT

The platform will “help [Amy] a lot in [her] training, especially building some core balance skills and being able to do some lunges and avoid the blade.” The ease of switching between a right- or left-handed orientation was another high point for Amy and her coach, not only to accommodate various fencers, but also to help develop Amy’s fencing skills and mobility.  This device not only has the potential to help improve Amy’s quality of life but also to make an impact on all those interested in becoming involved in wheelchair sports in the future.

TECHNICAL DESCRIPTION

The device has a rotating platform that easily adjusts for right-handed or left-handed fencers and it locks in place to the 110° measurement from the central axis required by IWAS.  The platform is also adaptable for various sizes and types of wheelchairs.  The tie-down systems ensure that all wheels on the wheelchair are secured to the frame and maintain their position during bouts.  In addition, the straps are designed so that the competitor can tighten them independently and from the seated position.  The entire platform is on tracks, which allows for easy movement to adjust the distance between the fencers.

To use this fencing frame, the competitor rolls up a ramp and onto the platform from the rear, aligning her wheelchair to the tie down system.  From there, the tie-down process can begin; the back and front wheels are secured, but not tightened completely.  Then the platform is rotated to either the right- or left-handed position, and the straps are tightened completely.  When both competitors are firmly secured, the distance between fencers can be set by moving the platform along the tracks to the desired location, and securing with a locking pin.

The rotating platform is comprised of two layers of plywood that support the weight of the wheelchair and fencer. The upper layer is circular, and it rotates to accommodate the angle of competition for either right-handed or left-handed fencers. The lower layer is a square, used to secure the platform to the track and provide support for rotation. Rotation is facilitated by a lazy Susan around the axis, and small caster wheels near the edges, that provide extra support.  A pin embedded at the back of the platform locks it in the neutral, right-handed, or left-handed position and keeps the platform from turning during bouts. The two tie-down systems are also attached to this component.  To keep the upper layer of the platform stable, aluminum strips are placed along the outer edge of the platform; these pieces of metal will counteract the force placed on the upper layer in bouts.

The front wheels need to be secured to eliminate any forward or backward movement and to keep the wheelchair on the frame during lunging.  This is accomplished using a ratchet strap with hooks on either end.  One hook of the strap attaches to the wheelchair frame, in a location that the competitor can easily reach while seated.  The strap then loops under a shackle that is connected to the platform, and is passed behind the foot bar of the wheelchair to the other side, where it is looped under a second shackle and brought back up, where it hooks onto the wheelchair frame again.

There are two separate ratchet straps for the back wheels, one for each wheel. For each strap, one end connects to a vertical pipe that is mounted on the platform, adjacent to each wheel.  The strap then loops through a ring that is connected to the platform, and the other end of the strap has been sewn into a large loop that the user places snugly over the top of the rear wheel. This design brings the ratchet mechanism to an accessible height to allow for easy tightening by the competitor from a seated position.

The fencing platforms rest on a pair of 11-foot long tracks.  These tracks serve as both a guide for movement and a locking mechanism to keep the platform from tipping during lunging. One platform is stationary and is secured by a hole-in-pin locking mechanism that secures the platform to the tracks. The second platform can transverse the length of the tracks using appliance rollers attached to the bottom of the platform.  It also locks into place using metal pins.  Large wheels on the ground of both platforms add stability and increase the transportability of the device.  For transporting the device, the tracks are hinged in the middle so that they can fold in half.

Figure 2: Clients using the Light Saber Fencing Platform

The platform sits just above the upper edge of the track so that an angle iron attached to the bottom of the platform runs along the side of the track.  A pin attaches through the angle iron and locks into the track.  This not only secures the platform in a specific lateral position, but it also aids in stabilizing the platform during lunging.  The holes along the track are spaced one inch apart, and the angle iron can move in smaller increments up to one inch to allow for fine adjustments of positioning.

The total cost of this device is $465.