tailieunhanh - Ebook Mechantronics an introduction: Part 2

(BQ) Part 2 book "Mechantronics an introduction" has contents: In troduction to sensors and actuators; fundamentals of time and frequency; sensor and actuator characteristics; the role of controls in mechatronics; system interfaces; the role of modeling in mechatronics design;. | Page 1 Monday, August 8, 2005 1:05 PM 9 Introduction to Sensors and Actuators M. Anjanappa University of Maryland Baltimore County K. Datta University of Maryland Baltimore County T. Song University of Maryland Baltimore County Sensors 9-1 Classification • Principle of Operation • Selection Criteria • Signal Conditioning • Calibration Actuators. 9-8 Classification • Principle of Operation • Selection Criteria Sensors and actuators are two critical components of every closed loop control system. Such a system is also called a mechatronics system. A typical mechatronics system as shown in Figure consists of a sensing unit, a controller, and an actuating unit. A sensing unit can be as simple as a single sensor or can consist of additional components such as filters, amplifiers, modulators, and other signal conditioners. The controller accepts the information from the sensing unit, makes decisions based on the control algorithm, and outputs commands to the actuating unit. The actuating unit consists of an actuator and optionally a power supply and a coupling mechanism. Sensors Sensor is a device that when exposed to a physical phenomenon (temperature, displacement, force, etc.) produces a proportional output signal (electrical, mechanical, magnetic, etc.). The term transducer is often used synonymously with sensors. However, ideally, a sensor is a device that responds to a change in the physical phenomenon. On the other hand, a transducer is a device that converts one form of energy into another form of energy. Sensors are transducers when they sense one form of energy input and output in a different form of energy. For example, a thermocouple responds to a temperature change (thermal energy) and outputs a proportional change in electromotive force (electrical energy). Therefore, a .