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Power Transmission and Gearing Systems
Published in Wei Tong, Mechanical Design and Manufacturing of Electric Motors, 2022
In recent years, the desire for designing more cost-effective and lightweight automation machines has led to the development of plastic SWG systems. As entirely made of plastic, this type of gearing system provides a number of advantages over its metal counterparts, such as lighter weight, less inertia, lower noise, and lower manufacturing cost. It is also resistant to certain corrosive environments. Some gearing systems are made of special materials for lubricant-free operation. However, this type of gearing system has some shortcomings relative to metal gears: Due to high wearing rates, the SWG system has low durability.Greater dimensional instability due to a larger coefficient of thermal expansion and moisture absorption.Since the flexspline must be flexible and deliberately deformed, it is typically made of special steel in a small thickness. The strain wave gearing system has lower rigidity with limited load-carrying capability.The flexspline is subjected to a cyclic elastic deformation during the rotation of the elliptical wave generator. This frequent deformation can fatigue the plastic material, causing the fatigue failure especially with long service time.
Mechanics of humanoid robot
Published in Advanced Robotics, 2020
Regarding rotary drives, a strain wave gearing such as Harmonic Drive® that is coaxial with the joint axis interfaces the actuator to the robot link. Spatial separation between the actuator and reduction gear is simply realized by using auxiliary transmissions such as synchronous drive belts. Rotary drives based on a strain wave gearing are simple in design and control due to the linear relationship of input and output. If strain wave gearings are arranged coaxially with the articulated joints, the movable part such as the ankle joint becomes heavy and the leg inertia becomes large, which may limit the dynamic performance of the walking robot.