Passive offset adjusting wheel mechanism

Small mobile robots have been studied for various purposes such as exploration and research. For small mobile robots, there is a trade-off between miniaturization and performance in overcoming steps, and it is desirable to improve the performance without increasing the number of actuators. Various methods such as crawlers, wheels, and leg transfers have been developed to achieve a high step-clearing performance without increasing the size of the mobile robot. Among these methods, we focused on the use of eccentric wheels. By eccentrically rotating the center of the wheel, the robot can traverse higher steps than that is capable by a normal wheel. Although this is a simple mechanism, the eccentric wheel has a disadvantage in that its traveling efficiency on flat roads is inferior to that of a normal wheel. In this study, we developed Passive offset adjusting wheels that automatically deforms into an eccentric wheel only when stepping over a bump and remains in the normal wheel state at other times. Experiments were conducted using a prototype rover with a wheel diameter of 120 mm, and it was confirmed that the eccentricity of the wheel was 50% higher than that of a normal wheel.