Efficiency optimization of high-reduction-ratio planetary gears for very high power density actuators

Small but powerful actuators are required for advanced robots for disaster response that need high-power motion as well as high mobility. To realize the small actuator using motors, compact and high power reduction gear plays important roll. The authors have been developing a high-reduction-ratio planetary gear. The gear realizes high reduction ratio, compact volume, high power transmission, and torque density. To achieve those high performance properties of the proposed gear, its efficiency is essential. We conducted improvement of its efficiency by optimizing profile-shift coefficients. Applying the proposed method, we can improve the efficiency over 10% theoretically.