Project Scope
Restore walking and hopping mobility to a single hind-legged pet rabbit with a motile prosthesis.
Project Considerations
- Proportional weight so the prosthesis doesn't strain the rabbit's remaining hip
- Flexible mounting that adapts to the rabbit's anatomy
- Sensor-driven kick timed to natural gait
- Mimic natural foot motion for effective push-off
Design Solution
- Single actuator drives both hip and kick motion
- Tunable elastic tendon adds compliance to the extension linkage
- Parallel linkage mimics a femur, tibia, and unified foot
- Interchangeable foot options, including a "Paralympic Sprinter" blade design
Assembled Project
- PETG construction with herringbone gears and F6 thrust bearings
- NEMA 17 stepper motor with a replaceable elastic tendon
- 280mm max extension, 240g leg mass, 115° hip range of motion
- Built for $24.91 in parts
Project Summary
This was an MTU Engineering Fundamentals team project that was presented at the Senior Design Expo. Hind-leg paralysis in pet rabbits, often caused by strokes or cancer, cuts off the motion their health depends on. We designed a prosthesis that mimics the rabbit's skeleton with a femur, tibia, and unified foot, adding an elastic tendon for compliance in the extension linkage. The first version used two stepper motors for independent control of the hip and kick motion, which gave dual-axis control but added weight and a more complicated control loop. Removing a stepper motor and linking the kick to the hip cut the weight by 35%. Kick control was simplified to a single flex sensor, worn in a sleeve on the rabbit's other leg, that drives the hip stepper through an Arduino Uno.
