1. Modification of a Wheelchair to Correct for One-Handed Use Joshua C. Nipper Mark M. Wasfy April 05, 2000 http://vubme.vuse.vanderbilt.edu/group22_99

2. Abstract zCurrent wheelchair designs are too complicated for users with both mental and physical disabilities to operate. A simple wheelchair design is needed that uses similar physical motions to produce both forward and rotary motion. We have designed a chair with an overrunning clutch to roll straight when the right wheel is pushed forward, and to rotate when the wheel is pulled backward.

3. Project Details zAdvisor: Aimee Eppler, Teacher at the Harris- Hillman School of Special Education zSubject: Mario - A 10 year old male, height 4’6”, weight 70 lbs. Severe Cerebral Palsy, leading to very poor co- ordination and physical ability

4. Cerebral Palsy zCerebral Palsy occurs in about 2/1000 births in industrialized countries zAbout 10% of these individuals have diplegia (impairment of all 4 limbs, but primarily in the legs) zThere are approximately 50,000 afflicted people such as Mario, plus many others with various disabilities

5. The Problem zMario’s lack of coordination impairs his ability to control his wheelchair zCurrently, Mario uses one hand (right) to push his chair and spins in a circle zWheelchair design needs to compensate for both physical AND mental disability

6. Design Constraints zOne-Handed Use yAllows, limited, steering control along with straight forward motion zSimplicity yComprehendible by mentally handicapped user zTime zCost efficiency y Donated materials and limited budget

7. Designsafe zDesignsafe was used to optimize safety features.

8. Solution: Two part, overrunning clutch axle system zOverrunning clutch linking left and right axle zAxle braces with bronze bushings mounting wheels parallel

9. Methodology zForce calculations were made to ensure that axle system would withstand torque with a considerable safety factor zRepairs: Tire inner-tubes, hand grips, cleaning zMachining of steel bronze bushing mounts zMachining of steel clutch converter zAligning, threading, machining of aluminum mounting brackets zMeasuring and cutting of steel axle zSmoothing of steel axle at 1500 rpm zEpoxy of clutch/converter, and bushing mount/mounting bracket zWelding new axle to existing wheel

10. Cost of Prototype zWheelchair and Clutch - Donated zRepair Items: Grips and Inner-tubes: $16.00 zBronze Bushings: $15.00 zAluminum Mounting Brackets: $18.00 zSteel mounts/connectors: $25.00 zSteel Axle: $4.00 zMisc.: $13.00 zTOTAL: $101.00

11. Conclusions zMario’s problem yCerebral palsy causes both physical and mental disabilities, causing his current wheelchair design to be too sophisticated zDesign restraints yThe wheelchair should move forward or rotate from one handed use, be of simplistic design, and be time and cost effective. zDesign solution yAn overrunning clutch was employed to allow for two distinct motions, forward or rotary

12. Recommendations zAdd an additional overrunning clutch to prevent the left wheel from spinning backwards when the right wheel is pulled backwards zCustomize Wheelchair Specific to Individual Users ySeat belt modification yArm rests, foot restraints, and brake positioning

13. Special Thanks: zAimee Eppler, Harris Hillman School zDr. Robert Joel Barnett, Research Associate in Mechanical Engineering, VUSE zPhil Davis, VUSE Machinist