Transcript Servo Motor
Group members MUHAMAAD DANISH USMAN ALI JAT MUREED SULTAN AZAN ASHRAF AYMEN TANVEER 2015MC05 2015MC14 2015MC18 2015MC19 2015MC29 Servo Motor What is servo motor? A servo motor is an electrical device which can push or rotate an object with great precision. Closed loop system (feed back). Types of servos Ac servo motor Dc servo motors Construction Of Servo Motor Servo motors consist of following basic parts: DC Motor Gear Box Potentiometer Control Circuit Sensor used is position sensor. Other sensors can also be used on the basis of its application. Working Of Servo Motor Control circuit of servo motor Servos are controlled by sending an electrical pulse of variable width. A servo motor can usually only turn 90 degrees in either direction for a total of 180 degree movement. The PWM sent to the motor determines position of the shaft, and based on the duration of the pulse sent via the control wire; the rotor will turn to the desired position. The servo motor expects to see a pulse every 20 milliseconds (ms) and the length of the pulse will determine how far the motor turns. OPTICOUPLE: Consists of a pair 1.Light Emitter 2.Light detector Encoders incorporated: Absolute encoders retain position information even when powered off. They also have no need for homing sensors or "homing" the axis when powered on. Incremental encoders: These are the most prevalent devices used on servomotors today, offering a standard interface that can be used on any servo drive. AC SERVO MOTOR AC servo motors are basically two-phase squirrel cage induction motors and are used for low power applications. TYPES OF AC SERVO MOTOR Synchronous type AC servo motor Induction type AC servo motor. Synchronous-type AC servo motor Synchronous-type AC servo motor consist of stator and rotor. The stator consists of a cylindrical frame and stator core. The armature coil wound around the stator core and the coil end is connected to with a lead wire through which current is provided to the motor. The rotor consists of a permanent magnet and hence they do not rely on AC induction type rotor that has current induced into it. Induction-type AC Servo Motor Induction motors are constructed of shortened wire loops on a rotating armature. Voltage is 'induced' in the rotor through electromagnetic induction. They are rugged, versatile, and can provide considerable power as well as variable speed control. Torque: We can increase or decrease torque of servo motor according to our requirements. 1.Increase torque using appropriate gears. 2.Mechanical advantage M.A = torque X gear ratio Applications of servo motor Robotics Radio control toy cars Airplanes Packaging machine CNC machine Conveyor belts Textile industry Braking System Advantages of servo motors We have a precise control over the operations of motor. These motors implies an error sensing feedback for better performance using PWM technique. Servo motor systems always know exactly where the motor is at, so all step commands are executed and no lost of pulses. High speed operation possible with more precision and are less noisy. Servomotors also draw less current than stepper motors, resulting in higher efficiency and lower heat production. Braking system