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What is the best motor technology to use in a motion control application? There are numerous technologies to create motion, from hydraulic to pneumatic or electromechanical. In the world of precision motion control, many machine designers face a choice between step motor or servo motor technologies to solve their performance requirements. Both stepper motors and servo motors have a place in the motion control world but understanding when to use each has created a big debate

There are several performance requirements that must be considered when selecting a stepper motor for an application. Our Stepper Optimizer tool is the fastest and most reliable way to determine these needs.

A stepper motor is a simple two phase brushless synchronous motor containing a segmented magnetized rotor and a stator consisting of a prescribed number of electromagnetic coils. When energized, these coils create north and south polls that push or pull the segmented magnetized rotor to make it spin.

There are several considerations when selecting a direct drive linear actuator for a specific application, such as the required speed, force, motion profile, available physical envelope, and environmental factors. This means the chosen actuator solution must produce the load force and speed requirements, fit in the available space, and perform as required under the subjected environmental conditions of the application.

A direct drive linear actuator, using a permanent magnet linear servo motor produces force and velocity based on the supplied current and voltage and provides a linear movement along the axis being driven. The linear servo motor works as part of a closed loop system providing force and velocity as commanded from a servo controller utilizing feedback to close the loop. In simple terms, a linear servo motor behaves identically as a rotary servo motor – it’s just rolled out flat and straight.

Phase margin is a measurement in the frequency domain, taken from a Bode plot, that calculates the amount of phase lag above -180 degrees at the point on the amplitude plot that crosses 0dB (gain cross over frequency).

Amplitude gain margin is a measurement in the frequency domain, taken from a Bode plot, that takes the amplitude below 0 dB at the lowest frequency point that the phase reaches -180 degrees (phase crossover frequency).

In simplified terms, bandwidth can be calculated as 1/(settling time) of a given step response of a servo system.

A servo drive is an electronic device that is part of a closed loop system, producing current and voltage to rotate a servo motor. The closed loop system includes the servo drive, servo motor and feedback device, and is commanded from an analog or digital signal.

A stable servo system is essential for optimal machine performance, durability, safety, and consistent machine performance, which improves overall machine operation. Servo systems operate in various degrees of stability, with a fine line between stable and unstable. Changes in the mechanical system over time or machines with varying loads can move the system from a stable to unstable operating condition. This article unveils four key values that determine the stability level of a servo system.


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