Conventional wheelchairs tend to roll over on inclined surfaces and also paraplegics struggle to move on a rough terrain. An attempt is made to address these challenges by providing a hand-lever and altering the C.G of the system. With suitable pivots at different levels the C.G of the system is shifted to a higher position away from the original C.G which helps paraplegics to climb over an inclined surface.
With regard to the rough terrain, hand-levers working on a typical chain drive helps paraplegics to move easily with less effort. The principle of mechanical advantage is being employed here. First, when the wheelchair is propelled by applying force at the top end of the levers i.e. away from the pivots, a greater torque is obtained which facilitates movement on non-smooth terrains. Second, when the wheelchair is propelled by applying force at the lower end of the levers i.e. closer to the pivots, the levers can be moved over a greater angle and hence facilitate traversing at a higher speed.
The reason for opting for a lever propelled mechanism is to attain a higher torque and velocity for easy and convenient usage by a disabled person. We were able to achieve 1.33% increase in torque and 110% increase in velocity than a conventional wheelchair. Also we demonstrated that the levers can be operated similar to a gear system. If we want to move on smooth terrain which requires high velocity but low torque we can push at lower end of the lever and for rough and uphill terrain we can push at the higher end. We achieved 14.5% increase in velocity and 13% decrease in torque while shifting from higher position of lever to a lower one sustainable for high velocity and low torque conditions suitable for a smooth terrain. We also achieved a 12.7% decrease in velocity and 15% increase in torque while shifting from lower position of lever to a higher position, very much required for a rough and uphill terrain. Hence we were able to demonstrate the concept of gear shifting in our wheelchair.
The incorporation of the alternating center of gravity mechanism was to increase the stability of the wheelchair on an uphill terrain. Usually conventional wheelchairs have their weight concentration i.e. center of gravity at the rear side of the wheelchair resulting in rolling over problems and painstaking propulsion. When we shift the seat forward the center of gravity shifts forward resulting in more stability and easy propulsion. The center of gravity gets shifted by 2.9 cm forward and 2.5cm upward when we shifted the seat forward. Our wheelchair can easily climb slopes of angle 10° inclination while conventional can climb till about 5° only.
ABOUT THE ENTRANT
Name: Achutha Tamraparni
Type of entry: team
Achutha Tamraparni, Yashwanth Dasappagari
Software used for this entry:
Patent status: none