stepper_ov - turned off, the gear rotates slightly to align...

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A stepper motor is a brushless, synchronous electric motor that can divide a full rotation into a large number of steps, for example, 200 steps. When commutated electronically, the motor's position can be controlled precisely, without any feedback mechanism. Stepper motors operate much differently from normal DC motors, which simply spin when voltage is applied to their terminals. Stepper motors, on the other hand, effectively have multiple "toothed" electromagnets arranged around a central metal gear, as shown at right. The electromagnets are energized by an external control circuit, such as a micro controller. To make the motor shaft turn, first one electromagnet is given power, which makes the gear's teeth magnetically attracted to the electromagnet's teeth. When the gear's teeth are thus aligned to the first electromagnet, they are slightly offset from the next electromagnet. So when the next electromagnet is turned on and the first is
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Unformatted text preview: turned off, the gear rotates slightly to align with the next one, and from there the process is repeated.Each of those slight rotations is called a "step." In that way, the motor can be turned a precise angle. There are two basic arrangements for the electromagnetic coils: bipolar and Unipolar. The top electromagnet (1) is charged, attracting the topmost four teeth of shaft. The top electromagnet (1) is turned off, and the right electromagnet (2) is charged, pulling the nearest four teeth to the right. This results in a rotation of 3.6. The bottom electromagnet (3) is charged; another 3.6 rotation occurs. The left electromagnet (4) is enabled, rotating again by 3.6. When the top electromagnet (1) is again charged, the teeth in the sprocket will have rotated by one tooth position; since there are 25 teeth, it will take 100 steps to make a full rotation....
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This note was uploaded on 02/23/2012 for the course CS 101 taught by Professor Martand during the Spring '10 term at Punjab Engineering College.

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stepper_ov - turned off, the gear rotates slightly to align...

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