Novel Design of a Climbing Mechanism for an Automatic Wheelchair

noneStair climbing wheelchairs were created to help disabled people and elderly overcome one of the most common architectural barrier, stairs. Many types of devices have been developed using tracked, leg, wheel and hybrid mechanisms to climb stairs but none of these have been able to ensure the safety and stability needed for stair climbing. This thesis presents a stair climbing wheelchair that uses an “X”-shaped wheel-leg mechanism to climb and descend stairs. This mechanism will always maintain contact with the stair during climbing activity to perform better at the climbing task. The seat of the wheelchair has 1 DOF so that the inclination angle can be changed in order to correct the position of the center of gravity to be close to the center of the supporting polygon. An IMU (Inertial measurement unit) is used to synchronize the angle of the seat in relation to the ground and by using a motor utilizing PID control to automatically balance the seat in the horizontal position. In order to climb stairs smoothly the angular position of the wheels should be the same, thus a PD control was implemented to control the position of the wheel so that they will be synchronized, therefore, capable of performing the climbing task at the same time and at the same position. Simulation and experimental procedures were done in order to analyze the behavior of the device while climbing and descending stairs and to know the system COG oscillations magnitude, which can produce discomfort to the user. The test results demonstrate the effectiveness of this mechanism and wheelchair