All Terrain Walker

Designers:  Dan Choi, Stephanie Chi, Fong Ming Hooi
Client Coordinator:  Barbara Howard, Duke University Hospital
Supervising Professor: Dr. Larry N. Bohs

The All Terrain Walker has been developed to help our client, a 12 year-old girl with cerebral palsy, travel more efficiently on rough surfaces.  An Otto Bock Busy Bee frame was modified by adding large front wheels, swivel rear wheels with shock absorption, an additional frame member for stability, and padded handlebar grips.  These modifications yield a responsive and stable all terrain walker that allows the user to travel on rough surfaces such as trails and grass, as well as on pavement and other smooth surfaces.

How this project helped
The All Terrain Walker will enable our client to participate in more outdoor activities with her family.  Her mother commented that “Mobility devices for [the client] = freedom. Freedom to get where she wants, when she wants, at a relatively normal rate of speed (or better!). This particular ‘all terrain walker’ will expand the geography of her world, since we otherwise could not go to the places it will get her to. I think the whole process of building it for her, with her input, also offered her more evidence that she has value as a human being. Otherwise, why would everyone bother?”

The All Terrain Walker (Figure 1) was created by modifying a commercial walker frame (Busy Bee, Otto Bock, Minneapolis, MN). The modifications included large front wheels to allow the client to negotiate rocks, roots, and other bumps, swivel rear wheels, frame stabilization, and padded handlebar grips.

The front swivel wheels of the Busy Bee were removed.  20” alloy wheels (Baby Jogger, Richmond, VA) were mounted to the front of the frame by welding on steel cylinders that accepted the quick release axles of the commercial wheels.  The cylinders were welded at the proper height to keep the frame level with these large wheels.

The fixed rear wheels of the original frame were replaced with two shock-absorbing swivel wheels (Frog Legs, Inc., Vinton, IA). The swivel wheels were attached using standard caster housings built for wheelchairs, which were bolted to a steel plate welded to the legs of the walker frame.  The walker frame was shortened in this area to account for the larger size of the Frog Legs casters compared to the original wheels.

The walker frame was stabilized by adding a 3/4” steel tube, bent to allow more rear clearance for the client’s feet and welded to the walker frame at the bottom of the rear legs.  The grips on the handrails of the original frame were replaced with tennis grip tape, which the client found more comfortable.

The client tested the All Terrain Walker on rough grass and found the walker to be easier to roll on such surfaces. One disadvantage is that the large front wheels also made it somewhat more difficult to control speed when going down a steep paved hill.  Because the walker is designed for off-road travel, it will require supervision until the user learns how to control its response.  Figure 2 shows the client using the walker.

Cost of parts for the All Terrain Walker was about $470.

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