Soft raising and lowering of front wheels for inverse pendulum control wheel chair robot

Wheel chair bound persons need assistance since there are many steps or curbs or other obstacles blocking their path in the roadways and walkways. Therefore, we are proposing a power assist wheel chair robot, which enables a wheel chair bound person to climb over steps of up to about 10 centimeters in height without assistance. By using the proposed wheel chair robot, a user can maintain inverse pendulum control after raising its front wheels. Then, a user can move forward to the step maintaining the inverse pendulum control, and can climb over the step using the DC motor force of rear wheel shafts. We have presented previously the front wheel raising scheme using rear wheel shaft movement. The inverse pendulum control has been conducted successfully. However, a rider on the robotic wheel chair felt a small shock since the front wheels were raised quickly. A new front wheel raising and lowering scheme is proposed in order to raise and lower the front wheels gently. The proposed scheme uses the rider´s seat movement. The raising speed could be slowed down about 20 times, and the overshoot could be decreased about 5 times.