Open-Loop Positioning A stepper motor has 48 step angles. Its output shaft is coupled to a ball screw with a 4:1 gear reduction (four turns of the motor shaft for each turn of the screw). The screw pitch = 5.0 mm. The worktable of a positioning system is driven by the screw. The table must move

Question

Open-Loop Positioning

A stepper motor has 48 step angles. Its output shaft is coupled to a ball screw with a 4:1 gear reduction (four turns of the motor shaft for each turn of the screw). The screw pitch = 5.0 mm. The worktable of a positioning system is driven by the screw. The table must move a distance of 75.0 mm from its current position at a travel speed of 400 mm/min. Determine (a) how many pulses are required to move the table the specified distance, (b) motor speed, and (c) pulse frequency required to achieve the desired table speed.

Accepted Answer

(a) To move a distance x = 75 mm , the ball screw must rotate through an angle calculated as follows:
[latex]A_s=\frac{360 x}{p}=\frac{360(75)}{5}[/latex] = 5400°
With 48 step angles and a gear reduction of 4, the number of pulses to move the table 75 mm is
[latex]n_p=\frac{4(48)(5400)}{360}[/latex] = 2880 pulses

Question 37.1: Open-Loop Positioning A stepper motor has 48 step angles. It...

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