Robotics in Mechanical Engineering
The word “robot” was introduced by the Czech playright Karel Capek in his 1920 play Rossum’s Universal Robots. The word “robota” in Czech means simply “work.” In spite of such practical beginnings, science fiction writers and early Hollywood movies have given us a romantic notion of robots. Thus, in the 1960s robots held out great promises for miraculously revolutionizing industry overnight. In fact, many of the more far-fetched expectations from robots have failed to materialize. For instance, in underwater assembly and oil mining, teleoperated robots are very difficult to manipulate and have largely been replaced or augmented by “smart” quick-fit couplings that simplify the assembly task. However, through good design practices and painstaking attention to detail, engineers have succeeded in applying robotic systems to a wide variety of industrial and manufacturing situations where the environment is structured or predictable. Today, through developments in computers and artificial intelligence techniques and often motivated by the space program, we are on the verge of another breakthrough in robotics that will afford some levels of autonomy in unstructured environments.
On a practical level, robots are distinguished from other electromechanical motion equipment by their dexterous manipulation capability in that robots can work, position, and move tools and other objects with far greater dexterity than other machines found in the factory. Process robot systems are functional components with grippers, end effectors, sensors, and process equipment organized to perform a controlled sequence of tasks to execute a process — they require sophisticated control systems.
The first successful commercial implementation of process robotics was in the U.S. automobile industry. The word “automation” was coined in the 1940s at Ford Motor Company, as a contraction of “automatic motivation.” By 1985 thousands of spot welding, machine loading, and material handling applications were working reliably. It is no longer possible to mass produce automobiles while meeting currently accepted quality and cost levels without using robots. By the beginning of 1995 there were over 25,000 robots in use in the U.S. automobile industry. More are applied to spot welding than any other process. For all applications and industries, the world’s stock of robots is expected to exceed 1,000,000 units by 1999.
The single most important factor in robot technology development to date has been the use of microprocessor-based control. By 1975 microprocessor controllers for robots made programming and executing coordinated motion of complex multiple degrees-of-freedom (DOF) robots practical and reliable. The robot industry experienced rapid growth and humans were replaced in several manufacturing processes requiring tool and/or workpiece manipulation. As a result the immediate and cumulative dangers of exposure of workers to manipulation-related hazards once accepted as necessary costs have been removed.
A distinguishing feature of robotics is its multidisciplinary nature — to successfully design robotic systems one must have a grasp of electrical, mechanical, industrial, and computer engineering, as well as economics and business practices. The purpose of this chapter is to provide a background in all these areas so that design for robotic applications may be confronted from a position of insight and confidence. The material covered here falls into two broad areas: function and analysis of the single robot, and design and analysis of robot-based systems and workcells.
providing a follow-on in mathematical terms of basic robot geometric issues. The next four sections provide particulars in end-effectors and tooling, sensors and actuators, robot programming languages, and dynamics and real-time control. Section 14.8 deals with planning and intelligent control. The next three sections cover the design of robotic systems for manufacturing and material handling. Specifically,Section 14.9 covers workcell layout and part feeding, Section 14.10 covers product design and economic analysis, and Section 14.11 deals with manufacturing and industrial processes. The final section deals with some special classes of robots including mobile robots, lightweight flexible arms, and the versatile parallel-link arms including the Stewart platform.