5.3 Introduction to Actuators etl. (7).pptx

Introduction to Actuators

1. 5.1 – Sensors and Actuators

2. Actuator Actuators Actuators are transducers. All these functions are performed by actuators. they convert one physical quantity into another. able to sense physical quantities in their environment systems must also be able to affect the outside world in some way so that their various functions can be performed. require the system to move something, change its temperature, or simply provide information via some form of display.

3. Actuator Actuator Classification based on Technology 1. Heat actuators Most heating elements may be considered as simple resistive heaters, which output the power that they absorb as heat. Special heating cables and elements are available for larger applications, which may dissipate many kilowatts. 2. Light actuators Most lighting for general illumination is generated using conventional incandescent or fluorescent lamps. The power requirements of such devices can range from a fraction of a watt to hundreds or perhaps thousands of watts .

4. Actuator Actuator Classification based on Technology 2. Light actuators Light-emitting diodes - One of the most common light sources used in electronic circuits. is a semiconductor diode constructed in such a way that it produces light when a current passes through it. Liquid crystal displays – (LCDs ) consist of two sheets of polarized glass with a thin layer of oily liquid sandwiched between them. An electric field is used to rotate the plane of polarization of the liquid in certain regions, making some parts of the display opaque while others are transparent. Fiber-optic communication - Fibers are usually made of either an optical polymer or glass. Glass fibers have a much lower attenuation and can be used over several hundred kilometers, but they are more expensive than polymer fibers. Short-range fiber-optic communication systems normally make use of LEDs as the light source, since they combine very high speed with a relatively low cost.

5. Actuator Force, displacement, and motion actuators In practice, actuators for producing force, displacement, and motion are often closely related . Solenoids - A solenoid consists of an electric coil and a ferromagnetic slug that can move into or out of the coil. When a current is passed through the solenoid, the slug is attracted towards the center of the coil with force determined by the current in the coil. Meters - Panel meters are important output devices in many electronic systems providing a visual indication of physical quantities.

6. Actuator Force, displacement, and motion actuators Motors - Electric motors of various forms can be used as force, displacement, or motion actuators. The motors fall into three broad types: AC motors, DC motors, and stepper motors. AC motors are primarily used in high-power applications and situations where great precision is not required. Control of these motors is often by simple ON/OFF techniques. DC motors are extensively used in precision position-control systems and other electronic systems, particularly in low-power applications. Stepper motors move in discrete steps, and their speed of rotation is directly controlled by the input waveform used. This combination of speed and controllability, together with small size and relatively low cost, makes stepper motors an attractive option in many applications.

7. Actuator Sound actuators The sound that we hear is basically made up of mechanical vibrations produced by an Audio Sound Transducer used to generate the acoustic waves, and for sound to be heard, it requires a medium for transmission either through the air, a liquid, or a solid . Speakers - Most speakers (or loudspeakers) have a fixed permanent magnet and a movable coil connected to a diaphragm. Input to the speaker generates a current in the coil, which causes it to move with respect to the magnet, thereby moving the diaphragm and generating sound . Ultrasonic transducers - At very high frequencies, the permanent-magnet speakers are often replaced by piezoelectric actuators. Such transducers are usually designed to operate over a narrow range of frequencies.