Collisions need not be dangerous for elliptical and flexible vehicles

We claim: Collisions need not be harmful for vehicles. If vehicles are designed to be elliptical and flexible, they need not suffer from damage due to collision. Additionally, wheel slippage can be reduced or avoided, if the vehicle's motors are switched off immediately when a collision occurs. This is because an appropriate elliptical shape transforms the repulsive collision force onto the vehicle's surface into a repulsive torque about the vehicle's center of rotation (COR). This torque turns the vehicle away from the collision region, thereby releasing the contact pressure and reducing the collision force. We realized such an elliptical, flexible vehicle by attaching an elliptical, flexible bumper system (TUMBLER.) to our small-sized experimental mobile robot YAMABICO. We confirmed by simulation the slippage-avoiding behavior in vehicle-wall collisions up to a speed of 0.5 m/s. We further confirmed by real vehicle-vehicle collision experiments the damage-avoidance feature up to a speed of 0.75 m/s. A similar behavior for large-sized vehicles and higher velocities (e.g. street vehicles) can be expected.