Explain the workings of stepper motors and servo motors.
Stepper Motor:
A stepper motor is a pulse-driven motor that changes the angular position. of the rotor in steps. Due to this nature of a stepper motor, it is widely used in low-cost open-loop position control systems.
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| Fig 1.1 Stepper Motor |
Types of stepper motor.
* Permanant magnet
- Employ permanent magnet
- low speed, Relatively high torque
* Variable Reluctance
- does not Permanant magnet
- low torque.
Permanent magnet (pm) stepper motor In this type of motor, The rotor isa permanent magnet, unlike the other Stepping motors, the em motor rotor no teeth of is designed to be magnitized at a right angle to o axis.
Shown a simple 90° Pm motor with Four phase applying current to each in sequence will Cause the Potor to rotate by adjusting to the Changing magnetic fields. Althought it operates at Fairly low speed "The PM motor has a relatively high Torque Characteristic. These are low lost motor with typical Step angle ranging bet 1.5 to 16"
A stepper motor is an electromechanical device that converts electrical pulses into specific, controlled movements. It operates in discrete steps, with each step representing a fixed angle of rotation. The motor consists of a rotor (rotating part) and a stator (stationary part) with coils of wire. By energizing the stator coils in a sequence, a magnetic field is created, causing the rotor to move in precise steps. A dedicated controller generates the required pulse sequence to control the motor's movement. Stepper motors find applications in 3D printers, CNC machines, robotics, and other systems requiring accurate positioning and control.
Application of servo motor:
Stepper motors have diverse applications in different industries. They're used in printers, CNC machines for precise cutting tool movement, 3D printers for layer-by-layer printing, robotics for accurate joint control, automotive systems (mirror movement, seat adjustment), medical devices, camera systems for autofocus, textile machinery, consumer electronics (DVD drives), and laboratory automation (liquid handling). Their ability to move in discrete steps and hold positions without feedback makes them suitable for applications requiring precision and reliability.
Advantage:
Stepper motors have advantages like precise positioning, open-loop control without the need for feedback devices, simplified setup without servo tuning, high torque at low speeds, a straightforward control interface, cost-effectiveness, reliability in holding positions without continuous power, ease of integration, and a high torque-to-inertia ratio. Their self-braking feature when not energized adds to their suitability for applications requiring precision, simplicity, and cost-effectiveness, like CNC machines and automation systems.
Stepper motors have drawbacks that impact their use in certain applications:
Limited High-Speed Torque:
They might experience reduced torque at higher speeds, restricting performance in applications needing swift movements.
Resonance Issues:
Stepper motors can produce vibrations and reduced accuracy due to resonance, requiring additional measures for damping.
Heat Generation:
Continuous operation or holding a position can lead to heat generation, necessitating additional cooling methods.
Complex Control for High-Speed Operation:
Achieving high-speed operation may demand more intricate control, counteracting the simplicity advantage at elevated speeds.
Power Consumption:
Stepper motors may consume excess power, especially when holding a
# Servomotor-
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| Fig 1.2 Servomotor |
Servomotor are special electronic device that produce precise degree of notation A servo motor is a oc or Ac or brash less ac motor combined with a position sensing divice servometer are also called control motor as they are involved. in controlling a mechanical system The servomotor, are used in a closed loop servo System as shown in tig A Reference i/p is sent to the cervo system as shown in Fig.
To the servo amplifier, which control the speed of the Gevemotor. A Feedback device is mounted of the machine which is either an encoder or' resolver
An electric motor, a feedback mechanism (such as an encoder or potentiometer), and control electronics combine to form a servo motor, which is a precision rotary actuator. It is a closed-loop system that is always tracking its position and adjusting in real time to keep precision.
Servo motors provide high-precision control and find applications in robotics, CNC machinery, conveyor systems, cameras, and industrial automation for tasks requiring accurate and controlled motion.
Application of servo motor:
Servo motors, known for precise motion control, have diverse applications.
They're used in robotics for joint movement, CNC machines in manufacturing, automotive systems (throttle control, mirrors), aerospace (control surfaces), consumer electronics (cameras, DVD players), medical devices, industrial automation (conveyors, packaging), satellite systems (antenna positioning), and educational robotics.
Their role extends to closed-loop control systems, ensuring accurate movements based on desired inputs.
Advantage:
Servo motors have advantages like precise control, high torque at high speeds, feedback mechanisms for accuracy, compact size, quick response times, energy efficiency, versatility across industries, smooth operation, a range of sizes, and overall reliability, making them ideal for applications in robotics, CNC machining, and industrial automation.
Difference between servo motor and stepper motor:
Stepper motors operate in an open-loop system, controlled by pulses without feedback. They're simpler and cost-effective but may lose steps and have lower performance. Common in applications needing precise positioning.
Servo motors work in a closed-loop system with feedback from a position sensor. They provide higher performance, accuracy, and speed. Ideal for applications demanding precise and dynamic control, such as industrial automation and robotics.
