tailieunhanh - Handbook of Machine Design P54

Elements of a Robot System In recent years, the so-called industrial robot has become a familiar feature of manufacturing plants. This class of machines is, of course, only a part of a much more diverse family of devices characterized by large numbers of degrees of freedom and intelligent controllers. | CHAPTER 47 ROBOTS AND SMART MACHINES Kenneth J. Waldron . Professor of Mechanical Engineering The Ohio State University INTRODUCTION DESIGN AND FUNCTION I STRUCTURAL DESIGN ACTUATION AND POWER TRANSMISSION SYSTEMS SENSING SYSTEMS COMPUTER HARDWARE AND SOFTWARE ORGANIZATION CONTROLLER DESIGN GEOMETRIC DESIGN TOOL DESIGN REFERENCES INTRODUCTION Elements of a Robot System In recent years the so-called industrial robot has become a familiar feature of manufacturing plants. This class of machines is of course only a part of a much more diverse family of devices characterized by large numbers of degrees of freedom and intelligent controllers. Industrial robots are however by far the most numerous visible and economically important group of devices in this family. For this reason much of the material in this chapter is directed at industrial robot design although an attempt is made to place them in an overall context of intelligent mechanical systems. Figure indicates the hardware subsystems present in a generalized industrial robot system. The manipulator usually has six independently actuated joints because a body which moves freely in space has six degrees of freedom. Consequently if the hand of the manipulator is to be placed in an arbitrary position and orientation within the manipulator s reach then the mechanism must have six degrees of freedom. Nevertheless some industrial robots on the market have as few as four or as many as seven degrees of freedom. Some types of tasks do not require the full six degrees of freedom and can be handled by four- or five-degree-of-freedom robots. Because the joints usually are not capable of complete rotation but can move only over a restricted angular range additional degrees of freedom beyond the basic six are often useful for demanding manipulative operations. The joints may be actu- STANDARD .