In-Link Actuators for Low-Inertia Robots

Manipulators are versatile and widely used as industrial robots, but they are also expected to be widely used in environments familiar to the general public. To facilitate close interaction with humans and to integrate into people's daily lives, safety is extremely important. By reducing the inertia of the moving parts of the robot, the kinetic energy of the robot can be reduced, thereby, increasing safety even when the robot is driven at high speed. In addition, when the inertia of a multidegree-of-freedom manipulator or robot is large, the output required for the actuators that support it becomes large. This results in a negative spiral in which actuators with large outputs are installed, and the actuators of the root link become increasingly larger to support them. Thus, low inertia is important as a means to improve the fundamental problems that affect a wide range of different robots. In this study, an in-link actuator is proposed, in which a drive unit consisting of coils and a magnet is directly incorporated into the links to reduce the inertia of the joints and the robot as a whole. Coils and a magnet embedded in each separate link make it possible to drive the links simply by combining them. An in-link actuator with drive performance aimed at practical use was fabricated, and through experiments, the drive performance as an actuator and the ability to significantly reduce the moment of inertia and some of its advantages were confirmed.