WHAT ARE FEEDBACK ACTUATORS?
A feedback actuator is a type of linear actuator that incorporates positional feedback, making it adaptable to applications where a closed-loop system is needed. A potentiometer is used to read the position of an actuator as it cycles. Our models such as the PA-14P and PA-17-POT use potentiometers that require 5 VDC input voltage and outputs a voltage signal that increases when extending and decreases when retracting. Feedback linear actuators are also referred to as potentiometer actuators or actuators with a potentiometer.
Reasons for feedback
Many applications may require a closed-loop system in order to correct for unexpected disturbances when controlling actuators autonomously. In order to have a closed-loop system, a device to transmit positional information will be required. Feedback, in this case, allows the ability to provide information to a control system and provide higher repeatability.
For example, cycling an actuator using timers to reach desired positions precisely and accurately is only possible if there are no disturbances that can vary how much the actuator travels over the time power is supplied based on timing. There are cases when a portable 12 VDC battery may supply a slightly lower voltage than it did initially which would decrease the actuator's speed while the timer does not change timing to correct for this disturbance. Sudden changes in a load's weight and wind resistance can also cause a disturbance in an actuator's travel speed that pre-programmed timers are unable to take into account. Feedback is necessary to transmit an actuator's position to a control system that can correct for the disturbances based on its programming. By reading the position, a control system will be able to determine if the desired position has been reached and will cycle the actuators for as long as needed accordingly. Our potentiometers found in PA-14P are examples of devices that provide feedback by outputting signals within the range of 0 to 5 VDC.
Potentiometer Set - PA-14P Models (PRT-14P-50)
APPLICATIONS FOR FEEDBACK ACTUATOR
The uses for feedback actuators can be found in a variety of different applications, some examples include home automation, prototyping, and robotics.
In-home automation, positional feedback from our PA-14P can be utilized to ensure that the actuator opens and closes a window accurately to the desired position of the operator. Positional feedback also ensures that the actuator does not overextends and crack the windows if the stroke length is slightly too long to fit.
Automated Window Demo
One of our sponsored projects which utilized potentiometer feedback would be the Human Powered Vehicle prototype. By sending positional information to an Arduino Uno, an actuator is able to retract and extend to the best positions required for changing spring tension of the prototype Human-powered vehicle to maximize efficiency.
Human Powered Vehicle
The positional feedback from potentiometers allows for improved accuracy, precision, and repeatability that can be found in the Stewart Platform such as the Six-Axis Platform. This project from the UBC Engineering Physics department allows for an interesting and interactive experience to learn about linear motion control as well as the physics that is involved in robotics.
Six-Axis Platform
Instructables.CONCLUSION
To summarize, positional feedback allows applications to have higher accuracy, precision, and repeatability. Feedback is especially useful for applications that experience unexpected disturbances or required positional information to re-adjust itself accordingly. If you require further assistance or have more questions on Feedback actuators, you may call us at 1-800-676-6123 or email us at sales@progressiveautomations.com.