1 / 18

Stepper Motors

Stepper Motors ME-191 Computer Applications in Mechanical Engineering II Dr. William Farrow Stepper Motor An output transducer that converts a digital signal to discrete rotational motion. Types of Stepper Motors Permanent Magnet Permanent Magnet Rotor (the part that rotates

Roberta
Download Presentation

Stepper Motors

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Stepper Motors ME-191 Computer Applications in Mechanical Engineering II Dr. William Farrow

  2. Stepper Motor • An output transducer that converts a digital signal to discrete rotational motion. ME-191 Computer Applications in Mechanical Engineering II

  3. Types of Stepper Motors • Permanent Magnet • Permanent Magnet Rotor (the part that rotates • Smaller size, Faster possible speeds • Lower max torques • Variable Reluctance • Iron or Steel Rotor • Larger size, Slower possible speeds • Larger max torques ME-191 Computer Applications in Mechanical Engineering II

  4. Permanent Magnet • Permanent magnet rotor’s magnetic field is driven around by attraction to and repulsion from electrically switched stator field coils (or poles). ME-191 Computer Applications in Mechanical Engineering II

  5. Variable Reluctance • Steel rotor seeks position of minimum reluctance under influence of the electrically switched stator field coils (or poles). ME-191 Computer Applications in Mechanical Engineering II

  6. Performance • Torque • PM limited to ~500 oz-in • VR limited to ~2000 oz-in • Speed • PM smaller rotor size  higher speeds • VR larger rotor size  smaller speeds ME-191 Computer Applications in Mechanical Engineering II

  7. Performance • Input speed • Measured in steps/second • Some PM’s can reach 30,000 steps/sec • Resolution • Measured in steps/revolution • Commonly 12, 24,144, 180, 200, and 400 • Or from 30°/step down to 0.9°/step • Half-stepping can further enhance resolution ME-191 Computer Applications in Mechanical Engineering II

  8. Important Parameters to Maintain Open Loop Control ME-191 Computer Applications in Mechanical Engineering II

  9. In Addition: • VR – holding torque is zero when power is off • PM – holding torque is generated by PM field and steel stators (detent torque) ME-191 Computer Applications in Mechanical Engineering II

  10. Typical Stepper Motor Characterics ME-191 Computer Applications in Mechanical Engineering II

  11. Lab 3 XY Table • Apply the concept of stepper motors to drive a XY positioning table ME-191 Computer Applications in Mechanical Engineering II

  12. XY Table Layout ME-191 Computer Applications in Mechanical Engineering II

  13. Stepper Motor Driver • Digital logic used to command stepper motor • This lab applies the UCN5804 IC to control the stepper motor via digital outputs from the LabJack • MOSFET power switching transistors used to amplify power to the stepper motor pole coils ME-191 Computer Applications in Mechanical Engineering II

  14. ME-191 Computer Applications in Mechanical Engineering II

  15. ME-191 Computer Applications in Mechanical Engineering II

  16. Stepping Signals • X-Axis step • D1 - direction • Low (0) or High (>0) opposite directions • D0 - move one step • High (>0) followed by a Low (0) • Note: requires two digital output calls • D8 & D9 - limit switches for travel • Inputs go high when switch is closed ME-191 Computer Applications in Mechanical Engineering II

  17. Lab Operation • Connect hardware and test using LJLogger • Write m-file to move X-Axis 100 steps ME-191 Computer Applications in Mechanical Engineering II

  18. Lab Operation cont. • Locate middle of Axis • Move x-axis until limit switch A is set • Will require While-loop and edigitalin() to monitor switch A • Reverse direction and count # of steps to B • Will require While-loop • Need to increment value in a variable steps • Reverse direction and move ½ the # steps • Require a For-loop to go ½ of steps ME-191 Computer Applications in Mechanical Engineering II

More Related