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Lever
The levers on this wheelchair were designed to reduced stress in the upper
extremities of the user (compared to a conventional hand rim). The lever
makes use of a freehub to allow for a ratchet mechanism for forward movement.
The lever mechanism also incorporates a spring loaded engagement mechanism
which allows the user to detach the levers while rolling backwards.
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Frame
The frame is primarily composed of aluminum tubing with welded
steel connectors. Finite element analysis revealed that most of the stress in
the frame occurs at the connectors, thus making steel a suitable choice at a
limited weight increase.
The frame was designed to support users weighing up to
250lb.
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Hub motors
Electric bicycle hub motors were adapted for use in this application.
Each motor provides 0.25 hp and a top speed of 15 km/h. The motors use a
3 phase 36 V power source and variable frequency controller.
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Seat
Memory foam seat contours to individual's body to alleviate
pain from long hours of sitting. The seat was hand stitched by one of the
members of our team.
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Battery
A NiCad battery was chosen for the prototype to provide reasonable weight
and performance characteristics. A LiPol battery could be used to further
reduce weight of the battery.
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Throttle
A single throttle is used to drive both hub motors in order to allow for a
straight trajectory with only one input. To steer, the user can brake
or ratchet on a particular side.
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