This paper details the design and development of a robotic joint actuator that combines a frameless BLDC motor with a two-stage stepped planetary gear reducer, as well as a custom-built controller for precise position control. The rotor is physically coupled to a hollow sun gear shaft to facilitate internal cable routing, and the actuator features a high-resolution absolute encoder utilizing the BiSS-C protocol. The controller includes a 3-phase H-bridge driver, differential signal conversion for encoder communication, and a CAN interface for host communication. Position control is achieved through a PID loop operating at 1 kHz. A prototype actuator and controller have been fabricated, and step response tests were conducted. Experimental results indicate stable and accurate tracking of position commands, with a short settling time of 0.04773 seconds. These findings confirm the effectiveness of the integrated actuator system for robotic joint applications. Future work will focus on optimizing internal cable space and implementing sensorless control algorithms.

This paper addresses the design of an integrated high torque DC motor. In this paper, a method to improve the torque according to the shape of the stator magnet and the rotor teeth of the DC motor is studied. During the course of design, the rotor and stator are designed to satisfy the required performance through FEM analysis by reflecting similar materials in design. As a result of satisfying the design result and requirements, the motor that is imported and operated in the future can be applied as a domestic developed product.