Actuator Report: Stepper Motor

Steve Gundersonchapodecalifornia@hotmail.com

(916) 662-4244

Utah State UniversityMarch 11, 2010

AcknowledgementsDr. YangQuan Chen: Research background and

technical instruction

AgendaOverviewImpact of engineeringPrinciple of operationTypesImplementationApplicationMajor specificationsLimitationsPurchasingReferences

Typical Stepper Motorhttp://en.wikipedia.org/wiki/Stepper_motor

OverviewStepper motors are brushless electric

motors that operate through a radial array of steps

The step sizes vary from motor to motor and can be used in control applications where a defined resolution is helpful with motor manipulation

OverviewStepper motors have become widely

implemented in many ways due to their controllability without any form of feedback loop

Even without feedback, a stepper motor may be controlled to a good degree of precision

Impact of EngineeringThe functionality of stepper motors has

been so widely accepted that they have revolutionized the usefulness and ease of implementation of electric motors

They can be used in stable and reliable control system that function with great precision and accuracy

Principle of OperationVoltage applied to

the motor causes the rotor to incrementally spin

More voltage causes more increments to be bypassed around the circle

Typical Stepper Motorhttp://en.wikipedia.org/wiki/Stepper_motor

TypesPermanent Magnet stepper motors

maintain a permanent magnet within the housing

Variable Reluctance stepper motors with iron rotors have rotor points attracted to stator magnet poles

Hybrid Synchronous stepper motors are the combination of the previous two for better performance

ImplementationStepper motor control

varies almost as widely as the stepper motors themselves

Control implementation is heavily dependent upon internal configuration and application needs

Stepper Motor Controlhttp://www.tigoe.net/pcomp/code/category/

arduinowiring/51

ImplementationDrive circuitry for bi-polar

stepper motors can be complicated but may be worth the additional torque that the actuator would be able to provide once configured properly Stepper Motor Control

http://www.tigoe.net/pcomp/code/category/arduinowiring/51

ImplementationHalf-stepping and micro-

stepping are two implementation modes where the angular resolution may be increased with little change to the control circuitry

Stepper Motor Controlhttp://www.tigoe.net/pcomp/code/category/

arduinowiring/51

ApplicationCountless types of stepper motor

configurations are in use today all throughout the world

A wide variety of markets can take advantage of them for precise control actuation

ApplicationSmaller high precision

stepper motors are often used for common actuation tasks

Their small enclosures are easy to mount to hardware and at low speeds can provide high torque

Stepper Motorshttp://news.thomasnet.com/IMT/archives/

2006/07/scavenge_materials_to_build_tinker_your_own_c

nc_machine.html

ApplicationRobotic systems can take

advantage of a stepper motor’s quick response and high precision without the constant need of a feedback loop

Where needed they can also interface with belts and drive trains

Stepper Motorhttp://www.designworldonline.com/uploads/ImageGallery/G4.Handler.stepper.motor.gif

Major SpecificationsMotors tend to vary widely in response

and must be characterized in order to properly control and implement them in a design

Stepper motor characteristic equations are a good start to understanding their behavior, as long as the control circuitry is also taken into account

LimitationsStepper motor resolution is completely

dependent upon the number of teeth on the rotor

As motor velocity increases, there is also a marked decrease in the total torque output which can comprise certain implementations of the actuator

LimitationsDifferent tooth constructions in the

motors can lead to varied efficiencies and controllability

More complicated motor designs also may require more complicated control electronics with amplifiers and many input lines

PurchasingStepper motors may be readily purchased

from many online retailersSmall electronic stepper motors are found

at digikey.com or mouser.comLarge-application stepper motors may be

obtained from specialty manufacturers and retailers

ReferencesWikipedia.org“Mechatronics – An Integrated Approach” by

Clarence W. de Silva

Questions?