Chapter 6 Electromechan e r m m c a a ni cal a S Sy s st ems e s 139 9 Copyright Goodheart-Willcox Co., Inc. Copyright Goodheart-Willcox Co., Inc. Summary • Electromechanical systems transfer power from one point to another through mechanical motion used to perform work. • A robot is a unique type of system that may require several different types of subsystems for proper operation. • An energy source provides power for a robotic system. The most common source of power for synthesized systems is alternating current (ac). • A transmission path provides a channel for the transfer of energy in a system. • A system control alters the fl ow of power and causes some type of fl operational change in the system, such as changes in electric current or hydraulic pressure. • The load of a system is a part or parts designed to produce work. Work occurs when energy is transformed into mechanical motion, heat, light, chemical action, or sound. • Indicators are used to display information about the operational condition throughout the system. • Mechanical systems, such as motors, linear actuators, cylinders, and reciprocating devices, produce some form of mechanical motion. • An electrical sensing system signals a response to a particular form of energy, such as light. Some sensing systems combine optics, electromagnetics, and electronics. • Electrical timing systems turn a device on or off at a specific time or in step fi with an operating sequence. • Control systems are used to make adjustments that alter machine operations. Open-loop and closed-loop systems are used to provide control. • Electric motors are rotary motion systems that convert electrical energy to rotary motion. • Direct current (dc) motors are used when speed control is essential. Permanent-magnet, series-wound, shunt-wound, and compound-wound are types of dc motors. • Single-phase ac motors operate using a single-phase ac power source. Three types of single-phase ac motors include universal motors, induction motors, and synchronous motors. • Servo systems are machines that change the position or speed of a mechanical object in response to system feedback or error signals. • Servomotors are used with robotic systems for precise control of rotary motion. DC stepping motors are used with robotic systems for precision motion control. • Robots require rotary electric actuators to produce rotary motion different from that produced by an electric motor. Review Questions Answer the following questions using the information provided in this chapter. 1. What is a subsystem? 2. What is a synthesized system? 3. What are fi ve basic subsystems that are common to all automated systems? fi 4. What is the function of a mechanical system?