Helios Ontrack Racing Wheelchair Case Study

Background

Faculty at the University of Houston recognized a need within the local middle and high school track and field programs. The schools in the Houston metropolitan area needed to support students that wanted to race wheelchairs. Dr. Michael Cottingham, founder of the UH Adaptive Sports Program, approached the HELIOS Ontrack Racing Company with an idea. As part of an International Design Competition, a team of Industrial Design students led by senior Richard Woodward set out to design a wheelchair for racing. With the support of Professor Eun Sook Kwon, the team consisting of John Proffitt, Jiachen Wang, Antoinette Vickio, Ray Jalufka, and Jesus Garate created an advanced, cost-effective racing wheelchair.

Goal

The goal was to supply the Houston metro middle and high schools with 150 racing wheelchairs, with two requirements:
  1. Design the racing wheelchair with an adjustable frame so that it can accommodate athletes of all sizes
  2. Keep the retail price of each wheelchair under $800

Challenges

Model Solution, a Laird company, became involved with the students in the competition, and built the prototype model of the racing wheelchair.
 
However, several challenges were encountered by the UH team and the MS engineers as they worked to meet the design requirements. Ensuring that the design worked for all athletes proved difficult in the early design. Even more complex issues arose with the machining process. The original design called for a relatively thin rear wheel compared to a normal large diameter, so machining them was difficult. Secondly, some of the fine features in the design were very small relative to the large wheel size, also adding to the machining difficulties. Finally, the thin wheels were often bent during the machining process, and needed to be repaired during the assembly stage. The UH students had difficulty modifying the CAD data to make the part easier to machine and assemble. The Model Solution engineering team made several modifications for the students to review and accept.

Solution

In order to keep the material costs down, the team designed a process that used press braked sheet metal construction rather than metal tubing for the racing wheelchair frame, and changed the process from a manual manufacturing process to an automated one. The process for developing the prototype model included design modifications, CNC machining, wet sanding and finishing of the frame, fabric wrapping, and final assembly. The model used an aluminum frame, with ABS, urethane and fabric for the interior features.

Results

Using 5052 Aluminum sheet metal versus tubing for the racing wheelchair frame resulted in a significant savings. For a single frame, the cost reduction was 60% (from $2,500 to $1,000). However, for 150 frames, the cost per frame came down by 82% (from $1,667 per frame to $300 per frame). In order to make entering and exiting the racing wheelchair safer, an anti-tip stand was integrated into the design.
 

Photos

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3D Printing
About Model Solution
Color Systems and Textures
Equipment
Machining
Manufacturing
Materials
Mock-up
Presentations
Tooling
HELIOS Ontrack Racing Wheelchair Model Side View
Complex design featuring ABS, urethane, aluminum and fabric
Helios Ontrack Racing Wheelchair Model
Complex design featuring ABS, urethane, aluminum and fabric
Helios Ontrack Racing Wheelchair Model Front View
Complex design featuring ABS, urethane, aluminum and fabric
HELIOS Ontrack Racing Wheelchair Model Bottom View
Complex design featuring ABS, urethane, aluminum and fabric