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# What Is a Linear Servo Actuator?

Article Details
• Written By: Paul Scott
• Edited By: E. E. Hubbard
2003-2018
Conjecture Corporation

 April 25 ,  1983 :  USSR leader Yuri Andropov wrote to Samantha Smith, an American grade schooler.  more...
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A linear servo actuator is a device used to supply straight line actuation of secondary mechanisms, the extent, direction, and duration of which are based on feedback signals from those mechanisms. In simpler terms, the servo actuator is used to operate a specific piece of machinery or equipment when and how the machine tells it to. This control is made possible by a series of sensors that provide readings regarding the real-time positional orientation of the secondary mechanism. A servo controller compares these readings to a set of pre-determined "desirable" parameters and establishes any discrepancies between the two. If any differences are detected, the controller then instructs the actuator to produce a correcting movement.

Linear servo actuator is a term that consists of three descriptive elements, namely actuator, servo, and linear. To fully understand the function of the linear servo actuator, it is necessary to appreciate the individual definitions of each of these elements. An actuator is a device used to supply a movement that is harnessed to produce remote activation of something else. For example, the device that remotely opens and closes a set of ventilation shutters is an actuator, as it supplies the movement necessary to operate the shutter mechanism. Actuators generally produce two different types of movement — linear or rotary.

The linear descriptor in the term refers to which of these two output movements the actuator produces. In this case, it is a linear, or forward and backward, movement. The third descriptive element is the most complex and describes the control source for the linear servo actuator. A servo system is one which produces a range of output results based on a set of system inputs or feedback. This is in contrast to conventional systems where the actuator is simply switched on and produces a finite, pre-set range of motion.

A linear servo actuator is capable of far finer control in response to the changing requirements of the system that it actuates. This control is made possible by including a servo controller and a set of environmental sensors in the system. The sensors will send a constant stream of real-time information to the controller, allowing it to build an accurate picture of the exact status of the mechanism in terms of its position. This information is then compared by the controller to a pre-determined ideal, or desired, status with the controller moving the actuator to the desired position if a discrepancy is detected. In this way, the linear servo actuator supplies controlling movement in a straight line according to system requirements courtesy of a servo controller.