An actuator control system is any electronic, electrical, or electromechanical system used to activate an actuator and control the direction, extent, and duration of its output. Actuator control systems may take the form of extremely simple, manually-operated start-and-stop stations, or sophisticated, programmable computer systems. The more advanced examples include servo systems that produce a wide range of actuator motion in response to the changing needs of the operational environment or process. This type of actuator control system utilizes an interface arrangement that assimilates feedback inputs from the process or mechanism, and adjusts the actuator accordingly. Most actuator systems will, however, include at least a set of travel limits that prevent the actuator from over-cycling and damaging itself or the secondary mechanism.
Actuators are remote or automated suppliers of working motion. They are used to switch, adjust, or move a secondary mechanism, where direct physical operator intervention is not possible or undesirable. They are represented by a wide range of different types using electrical and electromagnetic, hydraulic, or pneumatic power sources to produce linear or rotary outputs. The one element that they all have in common, though, is the actuator control system used to start, stop, and adjust the range, speed, and duration of the working motion. These systems range in complexity and functionality from simple start-and-stop buttons to highly-advanced servo controllers.
In the case of simple single-function mechanisms, the actuator control system will usually consist of a basic start-and-stop button if the actuator is manually operated, or a set of limit switches in the case of automated systems. A good example of this is a level controller on a water tank utilizing an actuated refill valve. A manual actuator controller will require an operator to start the valve actuator by pushing the start button. An automated system would typically include a float level switch that would close the actuator start circuit to open the valve when the water level dropped below a certain point. Once the tank is full, the float switch would start the actuator again to close the valve.
Installations that require constant adjustment of machine components according to changing operating conditions will, however, require a more flexible actuator control system capable of producing a range of actuator movement on demand. Known as servo systems, these controllers collect real-time positional feedback data from system or process sensors, and compare them with a set of ideal parameters. Any differences between the two data blocks will drive the actuator to correct the disparity. Both simple and multi-function actuator control systems will at least include a set of travel limits that prevent actuator or mechanism damage resulting from over-actuation.