Convertible Tri-Cane

Designers: Amanda Fuller, Yubo Gong, Toby Kraus
Client Coordinator:  :  Allison Darwin, OT
Supervising Professors: Kevin Caves

Our client is a 95 year-old man with a fused left knee and slight dementia. He enjoys walking outside, but tires easily and sometimes needs additional support, especially when walking on unfamiliar terrain.  The Convertible Tri-Cane is a single point cane that can be converted to a tri point cane for additional support.  The design uses a twist-and-push mechanism to allow the client to easily convert between modes. The Convertible Tri-Cane can be allows for either left or right-hand usage, and is also adjustable in height.

Although the client didn’t initially feel he needed the additional support, as the project progressed he appeared much more interested in the stability the tri-point mode provided.  His occupational therapist Allison Darwin stated, “Since we started this project, he has realized that he needs more stability.”  It is now easier and safer for the client to walk outdoors after converting to the tri-point mode:  he can walk faster, more comfortably, and without as much of a need for someone constantly looking out for him.

The Convertible Tri-Cane (Figure 1) includes tripod legs and a sliding mechanism that provides easy conversion between single and tri-point modes.  The tripod legs are made from 1/2″, furniture-grade, black PVC, bonded with heavy-duty cement. PVC was chosen instead of aluminum to minimize weight. The PVC legs connect to a pivot, made by mounting a 4-way joint onto the cane.  PVC extensions insert into the horizontal extensions of the joint, and are milled precisely to create a snug fit that still permits rotation.

An aluminum cross-brace connects the two legs together, and is through-bolted to each leg with two screws and nylon lockwashers.  To connect the tripod mechanism to the sliding mechanism on the shaft of the cane, two hinge-arms attach between the cross-brace and a shaft collar on base of the sliding mechanism.  The hinge-arms are attached to the cross-brace via a custom U-shaped steel bracket.  The sliding mechanism uses an aluminum tube, slightly larger in diameter than the client’s cane.  A slot milled vertically in this tube allows a pin on the cane shaft to keep the mechanism positioned properly. Two shaft collars at the top of the sliding tube allow the mechanism to lock in place.  The lower aluminum collar provides a secure attachment to the sliding tube.  The upper Delrin collar attaches to the lower collar, and provides a snug fit around the cane shaft.  A handled-screw in the Delrin collar allows the sliding mechanism to lock in place. When the screw is tight, the slider and thus the tripod legs are immobilized in either the up or down position; when it is loosened with about one-half to one-third of a turn of the handle, the sliding mechanism easily moves up and down.

Figure 2 shows the client using the cane. Cost of parts was about $400.

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