Servo actuators are used to provide position control, utilizing linear motion to maintain proper functioning of another mechanism or equipment part. At its most basic, a servo is a small device that operates based on responding to error-sensing feedback.
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Applications of Servo Actuators
While servomechanisms are used to provide and transmit a precise amount of energy used to correct a performance error through another mechanism that will provide the required work, servo actuators actually function to correct the performance error without the help of an additional device.
Servo actuators are often utilized in industries such as:
- Industrial Manufacturing
- For applications such as factory automation, instrumentation, and material handling robotics.
- For use in beam steering applications, as well as radio and remote-controlled vehicles.
- Marine and Aerospace
- In automatic navigation systems.
- For use in web guiding systems.
- For precision motion control of medical devices such as patient lifts.
Servo Actuator Design
Servo actuators consist of three main components: a servo motor, a set of gears and an output bearing. They can be powered through hydraulic, pneumatic, and electromechanical means; however, electromechanical and pneumatic servo actuators are more common than hydraulic. The choice of actuation depends on the power, speed, and precision requirements of the application. The most common types of gears used in servo actuators are worm gears and planetary gears. Worm gears are gears with a curved and recessed throat, whereas planetary gears consist of three or more small outer gears that rotate around a larger, central gear. The output bearing is commonly encased in a hard, protective housing, typically made from metals such as aluminum, zinc, or steel. The output bearing functions to allow for constrained linear motion between two or more mechanisms. In servo actuators, the bearing operates at an angle. The angle generally ranges from 0 to 180º, not exceeding 210º, and its movement is limited due to a mechanical stop that is attached to one of the gears.
Types of Servo Actuators
There are two main types of servo motors: brush and brushless. Well-suited for long stroke applications, a brush servo motor has a commutator with mechanical brushes that connect the power source to the armature or a rotating coil that induces voltage from motion through a magnetic field. Brushless servo motors, on the other hand, provide commutation through electrical means and, as a result, offer many advantages over the brush motor design such as a longer service life due to less mechanical wear and tear.