The Motor Encoder: When Closed Loop Control is Essential

An stepper motor encoder for sale is a rotary device that can be mounted onto an electric motor. It provides closed loop feedback signals, tracking the motor shaft’s position, speed, or both.

At first, this functionality might seem redundant. Isn’t precision control essentially what the stepper does on its own? The answer, it seems, is yes and no. Recent research has shown that the apparently “unnecessary” guidance provided by the encoder can have a powerful impact on how well a stepper motor works.

Motion controller brand Galil conducted a series of side by side tests between open and closed loop stepper motor systems. Their team discovered that the addition of an encoder could produce appreciable gains in major performance metrics.

Compared to the open loop system, the closed loop stepper motor offered:

Significantly improved velocity smoothness;

Reduced overall current consumption;

Higher torque at lower velocities than comparable three-phase brushless servo motors.

Galil's researchers determined that “dramatic” performance gains for stepper motors were possible by integrating a positional feedback device along with a two-phase brushless amplifier. Their testing methodology and results have been made public on their website.

These results are truly exciting news in the motion control world. Engineers at all levels can enhance stepper motors into even more powerful and economical solutions through the use of readily available encoder technologies.

KNOWLEDGE of CLOSED LOOP STEPPER SERVOS FOR EVERYONE

Why stepper motors? What about other types of motors?

Choosing an appropriate stepper motor such as nema size 17 can be difficult and time consuming. This webpage is intended to help you easily and quickly select a good stepper motor for your project. There is a lot to cover, so consider this the first part in the series.

Why stepper motors? What about other types of motors?
Stepper motors online are by far the most common types of motors used for CNC Machines. Stepper motors have a unique property that makes them particularly well suited for CNC motion. Each time a stepper motor receives a pulse, it only moves a certain amount. For a full step, this is usually 1.8 degrees and for a half-step this is usually 0.9 degrees. The reason this is important is because the computer running the motor doesn’t need to sense the actual position of the motor because the motor’s position can be calculated solely by how many pulses have been sent out.


Another possibility is to use PWM motors. These motors produce different torque depending on the duty cycle of a square wave signal it receives. However, a more complicated controller and an expensive quadrature encoder must be used to determine the current location of the motor at all times. This is a closed loop control system, where the system reacts based on position data which is detected through a sensor.