Application of stepper motors in industrial robots

Industrial manipulators are mechatronic automation equipment that imitate the movements of human hands and replace human hands to grab, transport workpieces or operate tools according to set procedures, trajectories and requirements.

Stepper motors are actuators that convert pulse signals into linear or angular displacement. The output displacement of a stepper motor is proportional to the number of input pulses, its speed is proportional to the number of input pulses per unit time (ie, pulse frequency), and its steering direction is related to the phase sequence assigned to each pulse of the stepper motor's phase windings. .Therefore, as long as the number and frequency of power-on command pulses and the phase sequence of the motor windings are controlled, the output displacement, speed and direction of the stepper motor can be controlled. Stepper motors have good control performance, and any change in operating mode such as starting, stopping, and reversing can be completed within a few pulses, and high control accuracy can be obtained, so they are widely used.

In the control system, PLC is used to generate control pulses, and a certain number of square wave pulses are output through PLC programming to control the rotation angle of the stepper motor and then control the feed amount of the servo mechanism. At the same time, the pulse frequency is controlled to control the feed speed of the servo mechanism through programming. . The ring pulse distributor distributes the control pulses output by the programmable controller to the corresponding windings according to the power-on sequence of the stepper motor.

Ring pulse distributors can be divided into software ring distributors and hardware ring distributors. Software ring distributor, that is, PLC uses software programming to output signals in sequence. For power stepper motors, a driving capability of tens to hundreds of volts is required, so a driver is used to amplify the output pulses. The method of using PLC to control three-phase stepper motors is simple, easy and reliable.

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