This book describes the design concept and discusses the control issues related to the performance of a direct-drive robot, specifically, a direct-drive mechanical arm capable of carrying up to 10 kilograms, at 10 meters per second, accelerating at 5 G (a unit of acceleration equal to the acceleration of gravity). These are remarkable achievements compared to current industrial robots that move with speeds on the order of 1 meter per second.Direct-Drive Robot presents the most current research in manipulator design and control, emphasizing the high-performance direct-drive robot arm in which the shafts of articulated joints are directly coupled to the rotors of motors with high torque. It describes fundamental technologies of key components such as motors, amplifiers and sensors, arm linkage design, and control system design, and makes significant contributions in the areas of power efficiency analysis, dynamic mass balancing, and decoupling theory.The book provides a good balance between theory and practice, covering the practical design and implementation of this special robot as well as the theoretical design tools.Contents: Part I: Direct-Drive Technologies. Introduction. Components. Part II: Arm Design Theory. Power Efficiency. Arm Design for Simplified Dynamics. Actuator Relocation. Design of Decoupled Arm Structures. Part III: Development of the MIT Arm. Mechanisms. Control Systems. Part IV: Selected Papers on Direct-Drive Robot Design and Control.Haruhiko Asada is an Associate Professor, Kyoto University, and Lecturer at MIT He has built two prototypes of the direct-drive arm described here. Kamal Youcef-Toumi is an Assistant Professor, Department of Mechanical Engineering, System Dynamics and Controls Division at MIT. He has worked for three years with Asada on the development of the MIT high speed directdrive robot.

An introduction to the design concept and control issues of the high-performance direct-drive robot arm.

This paper describes the design concept of a new robot based on the direct-drive method using rare-earth DC torque motors. Because these motors have high torque, light weight and compact size, we can construct robots with far better performance than those presently available. For example, we can eliminate all the transmission mechanism between the motors and their loads, such as reducers and chain belts, and construct a simple mechanism (direct-drive) where the arm links are directly coupled to the motor rotors. This elimination can lead to excellent performance: no backlash, low friction, low inertia, low compliance and high reliability, all of which are suited for high-speed high-precision robots. First we propose a basic configuration of direct-drive robots. Second a general procedure for designing direct-drive robots is shown, and the feasibility of direct drive for robot actuation is discussed in terms of weights and torques of joints. One of the difficulties in designing direct-drive robots is that motors to drive wrist joints are loads for motors to drive elbow joints and they are loads for motors at shoulders. To reduce this increasing series of loads is an essential issue for designing practical robots. We analyze the series of joint mass for a simplified kinematic model of the direct-drive robots, and show how the loads are reduced significantly by using rare-earth motors with light weight and high torque. We also discuss optimum kinematic structures with minimum arm weight. Finally, we describe the direct-drive robotic manipulator (CMU arm) developed at Carnegie-Mellon University, and verify the design theory. (Author).