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Typical Use: Position Control Relative position (without feedback) Easy to control: # Steps moved = number of pulses in Desired Velocity Step Rate Inexpensive Good holding torque No brushes Size Range: 1.3”L 10 oz-in $12. 9”L 2000 oz-in $700.
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Typical Use: Position Control Relative position (without feedback) Easy to control: # Steps moved = number of pulses in Desired Velocity Step Rate Inexpensive Good holding torque No brushes Size Range: 1.3”L 10 oz-in $12. 9”L 2000 oz-in $700. Can “lose” steps if load or pulse rate too high DC Stepper Motor
Permanent Magnet DC Motor • Typical Use: Variable Speed Control Position control is possible but requires additional hardware • Usually used with position or velocity feedback (optical encoder or tachometer) • Control: Speed Input voltage (DC or PWM) • Reduction gear heads common • Brushes wear out, spark, cause RFI • Size Range: Micro 0.5” L x 0.2”D (pager vibrator) $5 Big 13”L x 4”D 2 HP $1000 V2 >V1 Torque V1 RPM
Stepper Motor Speed vs Torque fmax Lost steps (stall) Step Rate Torque time TLOAD No lost steps w/acceleration (slewing) control No lost steps w/o acceleration control Step Rate - Hz ( Desired RPM) fmax Ref. (Figure 2.75), T. Kenjo, Stepping motors and their microprocessor controls, Oxford Press, 1984