14 AMT 311 - Servomechanism PDF

ELECTRONICS FUNDAMENTALS FINALS SERVOMECHANISM Objectives: 1. Define and describe the principle of servomechanism. 2. Enumerate where servomechanism is used in aircraft. Servomechanism - electric control system for an automatic powered mechanism that produces motion or force using a low...

ELECTRONICS FUNDAMENTALS FINALS SERVOMECHANISM Objectives: 1. Define and describe the principle of servomechanism. 2. Enumerate where servomechanism is used in aircraft. Servomechanism - electric control system for an automatic powered mechanism that produces motion or force using a low energy input signal. OPEN AND CLOSED SYSTEMS 1. Open loop system – the controls are set to the desired setting. 2. Closed servomechanism system – there is feedback, or follow-up, from the controlled unit. Differential Transducer - an electric device which converts the differing position of the physical flight control surface in to a variable electric output signal that can be processed by the controller. Linear Variable Differential Transducer - converts the linear motion into the electrical signal. Rotary Variable Differential Transducer - measures angular motion. It is a device that function by the motion of a rotor within the electro- magnetic field of the stator. SYNCHRO SYSTEMS - an electric system used for transmitting information from one point to another. - used as remote position indicators for landing gear, autopilot systems, radar, and many other remote-indicating applications. Synchro Systems 1. Autosyn 2. Selsyn 3. Magnesyn DC SELSYN SYSTEMS - consists of a transmitter, indicator, and connecting wires. AC SYNCHRO SYSTEMS AC Magnesyn System use permanent magnet motors. AC Autosyn System uses electromagnets, rather than permanent magnets. Modern AC Synchro Systems 1. Torque Synchro Systems – for transmitting position information 2. Control Synchro Systems – for systems where precision and control and feedback are required 3. Differential Synchro Systems – for applications where finding relative position between two objects 4. Resolver – for sensing and tracking the angular position of devices INDUCTANCE TRANSMITTERS - used in older instruments, acceleration sensors, and air data computers. - uses inductance windings similar to a synchro but the shape and spatial location is that of a letter “E”. CAPACITANCE TRANSMITTERS - used on aircraft to transmit condition. - most often in transport category aircraft fuel quantity systems. - it depends on three factors: area of its plates, the distance between the plates, and the dielectric constant of the material separating the plates.