Hybrid Stepper Advancements Improve Medical Pump Performance

Designers of medical pumps often have to deal with the challenge of implementing precise, yet low-cost motion control. For most medical pumps, there are three basic technology alternatives for implementing such electronic motion control: permanent magnet brush DC motors, brushless DC motors, or step motors. Step motors (sometimes called stepping motors, stepper motors, or simply steppers) are a solid choice for position or speed control. Steppers are inherently digital — a pulse applied to the drive electronics results in a shaft movement of one step. They are commonly used “open loop,” meaning without feedback, due to their ability to achieve the desired number of steps every time (if sized properly). The number of incoming pulses and the rate at which they are fed can be used to implement very precise, yet very simple motion (position, speed, and acceleration) control. As long as the speeds required are not too high (less than 3000 RPM, typically), steppers often offer a far simpler, lower-cost, and maintenance- free alternative.