Considerations and Tradeoffs between Stepper Motors and DC Motors Stepper Motors DC Motor Advantages Advantages• Simple, open loop control (just count steps!) • Low cost • Simple construction • Rugged • No maintenance (brushless) • High reliability • Inherently failsafe (no runaway) • Automatic braking • High continuous torque at low speeds • High speed capable • Higher torque at high speed • Torque speed curve more linear • Better dynamic response • Smoothness of motion • No maintenance (for brushless) • More efficient Disadvantages Disadvantages• Care needed in acceleration and deceleration to avoid missing steps • Relatively low speed (<3 kRPM) • Not smooth • Tend to run hot (some windings are always energized) • May jump 1 step after power on • Encoder or resolver needed to control position (adds complexity and cost) • Cost • Not smooth • Control is more complicated • Brush types are electrically noise • Not inherently failsafe (if encoder signal drops out, could run away) • No inherent braking Other Actuators to Know About • Linear motors (servo or stepper) • Linear actuators (PMDC or stepper driving a leadscrew) • SmartMotors • Piezo • Pneumatics • Hydraulics BJ Furman | ME 106 Intro to Mechatronics | Stepper vs. DC Motors and Other Actuators.doc | 17MAR2008 Page 1 of 2Other Actuators to Know About http://www.firgelliauto.com/images/Actuator%20dimensions%20June%2005.JPG http://animatics.com/images/home_page/sm2315dt_banner.gif http://www.firgelliauto.com/images/Track%20Actuator2.JPG http://www.dmicrotek.com/n412681/i414617.html http://www.motioncontrol.com/media/articles/full/2692_HPLAHLE%20Linear%20Actuators%20by%20Parker%20Hannifin.jpg http://www.pneumaticcylinders.net/content/cyl.jpg http://www.aerotech.com/products/motors/blmh.html http://www.peninsularcylinders.com/images/lhhpsw.jpg BJ Furman | ME 106 Intro to Mechatronics | Stepper vs. DC Motors and Other Actuators.doc | 17MAR2008 Page 2 of
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