ECE5320 Mechatronics Assignment#01: Literature Survey on Sensors and Actuators Topic: Stepper Motor Actuator

1. ECE5320 MechatronicsAssignment#01: Literature Survey on Sensors and Actuators Topic: Stepper Motor Actuator Prepared by: Kenneth Reese Dept. of Electrical and Computer Engineering Utah State University E:kbr@cc.usu.edu; T: (435)797-8276; F: (435)797-3054 (ECE Dept.) W: http://www.ece.usu.edu 3/11/2005

2. Outline • Reference list • To explore further • Major applications • Basic working principle illustrated • Types of stepper motors • Permanent magnet stepper motor • Variable reluctance stepper motors • Hybrid Stepper Motors ECE5320 Mechatronics. Assignment#1 Survey on sensors and actuators

3. Outline (continued) • Usage examples • Advantages • Limitations • Cost information • Where to buy stepper motors • How to choose a stepper motor • Questions ECE5320 Mechatronics. Assignment#1 Survey on sensors and actuators

4. Reference list • www.doc.ic.ac.uk/ ~ih/doc/stepper/ • www.machinetoolcamp.com • http://zone.ni.com/devzone/devzoneweb.nsf/ • http://computer.howstuffworks.com/floppy-disk-drive.htm • http://computer.howstuffworks.com/inkjet-printer.htm • www.imagesco.com/articles/picstepper/02.html • Parker Compumotor Division ECE5320 Mechatronics. Assignment#1 Survey on sensors and actuators

5. To explore further • www.doc.ic.ac.uk/ ~ih/doc/stepper/ • www.machinetoolcamp.com • http://zone.ni.com/devzone/devzoneweb.nsf/ • http://stepper-motors.globalspec.com/directory/Motion_Controls/Motors/Stepper_Motors • http://www.parex.org/weblog/archive/000049.html • http://robothaven.net/article.pl?sid=04/09/19/0431252&mode=thread ECE5320 Mechatronics. Assignment#1 Survey on sensors and actuators

6. Major applications • Computer Peripherals • Printers • Plotters • Disk Drives • Office Machines • Photocopy Machine • Fax Machine • Space Vehicles/Satellites • Industrial Control • Medical Equipment • In general, whenever stepping from one position to another. courtesy of www.machinetoolcamp.com ECE5320 Mechatronics. Assignment#1 Survey on sensors and actuators

7. Basic Working Principle I • Uses electromagnetics to make the motor shaft turn a precise distance when a pulse is provided • Rotor and stator both have magnetic dipoles • The number of degrees the rotor will turn per pulse is 360°/(# of poles in the rotor) courtesy of Parker Compumotor Division ECE5320 Mechatronics. Assignment#1 Survey on sensors and actuators

8. Basic Working Principle II • Unlike AC motors, DC motors, and hydraulic/pneumatic actuators, stepper motors have an incremental-drive (digital) actuator. • Uses a translator to convert step and direction logic signals into winding energization patterns Courtesy of http://www.columbia.edu/~ag2363/e3410/motors101.pdf ECE5320 Mechatronics. Assignment#1 Survey on sensors and actuators

9. Basic Working Principle III • Stepper motors have holding torque, allowing them to hold their position when not turning. The poles of the rotor align with the poles of the stator. • When power is applied, it is to only one stator pole, making it a magnet. courtesy of Parker Compumotor Division ECE5320 Mechatronics. Assignment#1 Survey on sensors and actuators

10. Basic Working Principle IV • The stator coil that is the north pole will attract the closest rotor tooth that has the opposite polarity. • By changing the current flow to the next stator winding, the magnetic field will be changed by 360°/(# stator poles). The rotor will rotate by 360°/(# rotor poles*# phases). • The magnetic field in the stator is continually changed as the rotor moves through all steps to move a total of 360 courtesy of Parker Compumotor Division Courtesy of http://www.columbia.edu/~ag2363/e3410/motors101.pdf ECE5320 Mechatronics. Assignment#1 Survey on sensors and actuators

11. Types of Stepper Motors • Permanent Magnet • Uses a permanent magnet rotor • Low speed • Variable Reluctance • Low Torque • Hybrid • Most widely used ECE5320 Mechatronics. Assignment#1 Survey on sensors and actuators

12. Permanent Magnet Stepper Motor • Uses a canstack rotor (shown in figure) • This rotor can have multiple windings, meaning shorter steps • No brushes required • Relatively low speed and torque courtesy of Parker Compumotor Division ECE5320 Mechatronics. Assignment#1 Survey on sensors and actuators

13. Does not use permanent magnets Magnetic field produced by winding currents Field strength can be varied Amount of Torque is still small Can not use the same type of controller as other types of stepper motors Uses: Positioning tables Small positioning loads Applications with a larger step size Variable Reluctance Stepper Motor ECE5320 Mechatronics. Assignment#1 Survey on sensors and actuators

14. Hybrid Stepper Motor • Most Widely Used • Combines the principles of permanent magnet and variable reluctance motors • Small step length • Greater torque courtesy of Pacific Scientific ECE5320 Mechatronics. Assignment#1 Survey on sensors and actuators

15. Usage Example IIndustrial application • Generally higher torque applications (Hybrid type stepper motor). • Cheaper alternative to conventional DC motors • Packaging, semiconductor, automotive, food processing, pharmaceutical, and scientific applications courtesy of www.industrialnewsroom.com/ ECE5320 Mechatronics. Assignment#1 Survey on sensors and actuators

16. Usage Example IIFloppy Disk Drive • The read/write assembly head is fastened to the stepper motor shaft • Move the read/write assembly to the proper track position on the magnetic medium. • Must be very precise courtesy of bigbro.biophys.cornell.edu/~toombes/Pictures// ECE5320 Mechatronics. Assignment#1 Survey on sensors and actuators

17. Usage Example IIIInkJet Printer • Position the print head assembly at the precise location on the paper • Sharp changes in acceleration • Can produce unwanted vibration in printing function courtesy ofhttp://computer.howstuffworks.com/inkjet-printer2.htm ECE5320 Mechatronics. Assignment#1 Survey on sensors and actuators

18. Advantages • Position error is noncumulative. A high accuracy of motion is possible, even under open-loop control. • Large savings in sensor (measurement system) and controller costs are possible when the open-loop mode is used. • Because of the incremental nature of command and motion, step motors are easily adaptable to digital control applications. ECE5320 Mechatronics. Assignment#1 Survey on sensors and actuators

19. More Advantages • No serious stability problems exist, even under open-loop control • Torque capacity and power requirements can be optimized and the response can be controlled by electronic switching • Low maintenance (brushless) • Very rugged in almost any environment • No tuning required ECE5320 Mechatronics. Assignment#1 Survey on sensors and actuators

20. Limitations • Low torque capacity (typically less than 2,000 oz-in) compared to DC motors • Limited speed • Rough performance at low speeds • High vibration levels due to stepwise motion • Large errors and oscillations can result when a pulse is missed under open-loop control • Limited sizes available courtesy of http://www.stepper3.com/ ECE5320 Mechatronics. Assignment#1 Survey on sensors and actuators

21. Cost Information • The average price for a small to medium used stepper motor is $5.00-$15.00 • Upper end industrial or high torque stepper motors are typically $200-$300. • Stepper motors are typically less expensive than a servo motor of a similar size. • Used stepper motors can be found easily in old dot-matrix printers and floppy disk drives ECE5320 Mechatronics. Assignment#1 Survey on sensors and actuators

22. Where to Buy • Electronic Inventory Online • www.eio.com • Parker Hannifin, Electromechanical Automation • http://www.parkermotion.com • Digikey • www.digikey.com • Saia-Burgess (industrial and automotive) • www.saia-burgessusa.com • Nyden (High torque, small step size) • www.nyden.com • Stepper3 LLC • www.stepper3.com/ ECE5320 Mechatronics. Assignment#1 Survey on sensors and actuators

23. Items to consider Sensitivity Power Consumption Motion Resolution Precision Bandwidth Response time Repeatability Cost Motor Chacteristics Voltage rating Resistance-per-winding Degrees per step How to Choose a Stepper Motor ECE5320 Mechatronics. Assignment#1 Survey on sensors and actuators

24. Questions ECE5320 Mechatronics. Assignment#1 Survey on sensors and actuators