In general the main use of stepper motors is in applications where positional accuracy is hugely important. Whereas a traditional brushed DC motor turns constantly as soon as power is applied, a stepper motor can be turned a controlled number of steps. Depending on the number of degrees per step in the motor (this varies from motor to motor but in a standard 200 step motor this equates to 1.8 degrees per step) this can then enable the motor to move from one fixed position to another fixed position. By using intelligent controllers such as the ZD series of stepper motor drivers, this movement can then be controlled very accurately with programmable acceleration and deceleration curves being applied.
The simplest case study of this type of application is the rotary prism system that we built. Whereas a brushed or brushless DC motor would require careful calibration, timing and the use of encoders and limit switches to rotate a prism 120 degrees, wait a set time and rotate another 120 degrees, with a stepper this can be achieved relatively easily because it is possible to measure the exact number of steps required to make this movement and use an intelligent controller to make this movement.
If one considers more complex applications such as robotics or highly accurate dosing equipment then one can appreciate how useful having this level of control would be. By adding a controller capable of microstepping such as the ZD4 Stepper Motor Driver (this offers up to 128 microsteps) it is possible to gain exceptional positional accuracy. Based on a standard 1.8 degree 200 step stepper motor, the ZD4 Stepper Motor Driver can move accurately between any of 25600 points of a circle.
Fundamentally, it can therefore be the key advantages of stepper motors is that they enable the motor to stop and start at any point required with exceptional accuracy. In combination with an intelligent stepper motor controller it is possible to achieve exceptional positional accuracy and performance from a stepper motor.