Abstract
Wheelchair fencing is a recognized Paralympic sport practiced in 26 countries1 but is not very common in the area. Our client recently began participating in the sport and lacked the funding to purchase the fencing frames currently used in international competition. Therefore, she practiced without securing herself to anything, which was unsafe and put her at a disadvantage due to her unfamiliarity with being fixed to a platform.
This report presents further information on our client’s disability and her requirements for the project. It also explains the design, development, and evaluation of the device. The fencing frame provided our client with a safe way to practice fencing and will allow her to improve her training regimen to reach her goal of joining a Paralympic team for wheelchair fencing.
Introduction and background
Osteogenesis imperfecta (OI), commonly known as “brittle bone disease,” is a congenital disorder that affects the strength of the bones in the body.2 The symptoms of OI vary by person and include hearing loss, weakened bones or muscles, lack of joint flexibility, and short stature.3 Our client Amy has been diagnosed with Type III OI. 4 She is completely dependent on her wheelchair for mobility but is able to lean side to side and rotate her upper body from the seated position. These characteristics have served Amy well in pursuing her interests in athletics. She has competed in track and field events for many years and has recently begun training to become a Paralympic wheelchair fencer.
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.5 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.
Though fencing frames are available for purchase, our client currently trains without one because existing models are less than ideal for use in a practice setting. Platforms that are sturdy enough to withstand a daily training regimen 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 Amy 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.
Problem Statement
The goal of this project was to design and develop a fencing frame that will allow Amy to practice with other fencers (both able-bodied and disabled) in a safe manner. The platform built adheres to the specifications outlined in the IWAS manual on wheelchair fencing6 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.
Design and Development (Methods)
Our design has three main components: rotational platforms to which the wheelchairs are secured, front and back wheel tie-down systems, and a track to aide in moving the platforms laterally to set the distance between fencers. As outlined in the project goals, our fencing frame complies with all characteristics mandated by the IWAS and the additional features requested by our client. The device has a rotating platform that easily adjusts for right-handed or left-handed fencers and is accurately set to the 110° measurement from the central axis required by IWAS. The platform is also adaptable for various sizes of wheelchairs and can be used with any type. The tie-down systems ensure that all wheels are secured to the frame as well as maintaining the position of the wheelchair during bouts. In addition, the straps are designed so that the competitor can tighten them independently and from the seated position. Finally, the tracks allow for easy movement of the platforms to adjust the distance between the fencers.
To use this fencing frame, the competitor will roll onto the platform from the back, aligning her wheelchair to the metal pipe on her dominant side. From there, the tie-down process can begin; the back and front wheels should be secured, but not tightened completely, before rotating the platform. Once the platform is set to either the right- or left-handed position, the straps can be tightened completely. When both competitors are firmly secured, the distance between fencers can be set by unlocking the pins on the sides of the translational platform, moving the platform to the desired location, and locking the pin in place.
I. Rotating platform
The rotating platform is comprised of two large pieces of wood that support the weight of the wheelchair and fencer (Figure 1). The upper layer is cut into a circle that rotates to accommodate the angle of competition for either right-handed or left-handed fencers. The bottom layer is a square used to secure the platform to the track (see below) and provide support for rotation. Rotation of the circle is facilitated by a Lazy Susan at the center and small caster wheels near the edges. A pin (Figure 1A) 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 explained below are also attached to this component. The parts labeled B are the hooks to which the front tie-down attaches, while C shows the pipes and ratchet straps used for the back tie-down. To keep the upper circle from lifting during lunging, aluminum strips are placed along the outer edge of the platform (Figure 1D); these pieces of metal will counteract the force placed on the upper layer in bouts and keep the platform stable.
II. Tie-down Systems
A) Front wheel
The front wheels need to be secured to eliminate any forward or backward movement and to keep the wheelchair on the frame during lunging. A ratchet strap is used to firmly hold down the front of the wheelchair. As can be seen in Figures 2 and 3, one hook of the strap attaches to the wheelchair in a location that the competitor can easily reach while seated. The strap then loops under a shackle and is passed behind the foot bar to the other side, where it is looped under a second shackle and brought back up. The hook attached to the ratchet is connected to an accessible location on the wheelchair so that the competitor is able to tighten the strap while in the chair.
B) Back wheels
The tie-downs on the back wheels use the same mechanism as that in the front. The strap (A) has been sewn in a loop that sits at a 90° angle and fits snugly over the top of the wheel, as shown in Figure 4. The remainder of the strap is looped through a ring on the platform (B), and the ratchet is placed on a metal pipe (C). This design brings the ratchet to an accessible height to allow for easy tightening by the competitor from a seated position. The height of the pipe is dictated by the diameter of the wheel so that it does not interfere with the fencer during competition.
III. Track
The track acts as both a guide for movement and a locking mechanism to keep the platform from tipping during lunging. One platform will be stationary and will be secured by a hole-in-pin locking mechanism under the platform. The second platform will transverse the length of the tracks using the appliance rollers attached to the bottom of the platform. Figure 5 shows the frame completely set up for two competitors. Large wheels on the ground of both platforms add stability and increase the transportability of the device. The 11 foot tracks are hinged in the middle to increase portability.
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 (Figure 6). A pin is attached 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.
Summary
The components of our device come together to produce a durable platform that fully complies with all design constraints and criteria. Each piece is specifically fabricated to hold the weight of the wheelchair and competitor while employing the lightest materials possible to contribute to portability. This novel design provides our client with an innovative fencing frame that overcomes many of the issues with current platforms and provides her with a competitive advantage in her training.
Evaluation
The device significantly improves the practice conditions for Amy, as she is much safer when secured to the platform, and her training more closely simulates competition circumstances. To test the device, we first transported it to the gym in the van that will be used to travel to competitions, to ensure that the device would fit comfortably inside. We then set up the frame in the gym and had Amy and another fencer secure themselves onto each platform and fence each other to simulate practice conditions. The device held up well, and Amy affirmed that using this frame felt similar to the other fencing frames she used at national competitions. Amy and her coach commented on the platform, sharing their thoughts on how well it complied with the project goals; this evaluation can be seen in Appendix C, Section 3.
Discussion and Conclusions
The device is very obviously an improvement for Amy’s quality of life and satisfaction. Having competed at the national level after practicing for several months without any sort of securing tie-down, Amy was unfamiliar with how her wheelchair would respond when lunging, which put her at a disadvantage compared to other competitors. However, now that she has this frame, which feels comparable to what she used during competition, she will be able to prepare adequately for future international matches and continue her training for the 2016 Paralympics.
Furthermore, the final price of the device came to approximately $360, which is several hundreds to thousands of dollars cheaper than other commercially available fencing frames. The design also surpasses that of other frames by eliminating mechanically weak areas commonly seen in other fencing frames. Based on this and the feedback from Amy and her coach, our device visibly performs on par with or better than other available frames during bouts, making this design strongly competitive with others.
References
- IWAS Sports, (2012) Wheelchair Fencing. [Online]. Available: http://www.iwasf.com/iwasf/index.cfm/sports/iwas-wheelchair-fencing/
- National Center for Biotechnology Information. (2011, Aug. 2) Osteogenesis Imperfecta. [Online]. Available: http://www.ncbi.nlm.nih.gov/pubmedhealth/PMH0002540/
- Osteogenesis Imperfecta Foundation. (2007) Facts about Osteogenesis Imperfecta. [Online]. Available: http://www.oif.org/site/PageServer?pagename=AOI_FactsInternational
- Osteogenesis Imperfecta Foundation. (2007) Types of OI. [Online]. Available: http://www.oif.org/site/PageServer?pagename=AOI_Types
- Wheelchair and Amputee Sports Foundation (IWAS). (2012) Wheelchair Fencing. [Online]. Available: http://www.paralympic.org/Sport/IOSD_Sports/Wheelchair_Fencing/
- “Book 3 – Material Rules” in IWF Rules for Competition. 2011, pp. 1-63.
Acknowledgements
We would like to acknowledge a number of people for their help in completing this project:
National Science Foundation grant # CBET 3310005
Kevin Caves
Richard Goldberg
Juan Pablo Garcia
Mid-South Gym coaches and fencers