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Motion Control, in electronic
terms, means to accurately control the movement of an object
based on either speed, distance, load, inertia or a
combination of all these factors. There are numerous types
of motion control systems, including; Stepper Motor, Linear
Step Motor, DC Brush, Brushless, Servo, Brushless Servo and
more. This document will concentrate on Step Motor
technology.
In Theory, a Stepper motor is
a marvel in simplicity. It has no brushes, or contacts.
Basically it's a synchronous motor with the magnetic field
electronically switched to rotate the armature magnet
around.
A Stepping Motor System
consists of three basic elements, often combined with some
type of user interface (Host Computer, PLC or Dumb
Terminal):
The Indexer (or Controller)
is a microprocessor capable of generating step pulses and
direction signals for the driver. In addition, the indexer
is typically required to perform many other sophisticated
command functions.
The Driver (or Amplifier)
converts the indexer command signals into the power
necessary to energize the motor windings. There are numerous
types of drivers, with different current/amperage ratings
and construction technology. Not all drivers are suitable to
run all motors, so when designing a Motion Control System
the driver selection process is critical.
The Step Motor is an
electromagnetic device that converts digital pulses into
mechanical shaft rotation. Advantages of step motors are low
cost, high reliability, high torque at low speeds and a
simple, rugged construction that operates in almost any
environment. The main disadvantages in using a step motor is
the resonance effect often exhibited at low speeds and
decreasing torque with increasing speed.
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