Electric linear actuators with positional feedback electronics are capable of performing some impressive moves within various applications. But what exactly is a linear actuator with feedback and what are some example applications where they have been used to their full potential? In this article, we will dive into the specifics of feedback actuators and run through a few example applications such as an automated window, a human powered vehicle, and a six-axis platform.
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 closed-loop system involves reading the output signal of a system by using a sensor and passing that signal to a controller. The controller determines the error value of the signal and sends a correction signal back through the system. This feedback correction continues until the error signal is within an acceptable range.
A linear actuator with potentiometer feedback is used to read the position of an actuator (system) as it cycles. The controller can be an Arduino, for example. Our models include the PA-04-HS which uses Hall effect feedback, and the PA-14P and PA-17-POT which use potentiometers that require a 5 VDC input voltage. The potentiometer models output a voltage signal that increases when the actuator extends and decreases when it retracts. A linear actuator with feedback can also referred to as a Hall effect actuator, potentiometer actuator or a linear actuator with potentiometer feedback.
Reasons for Feedback
Many applications may require a closed-loop system in order to correct for unexpected disturbances when controlling actuators autonomously. As mentioned previously, in order to have a closed-loop system, a device is needed to transmit positional information. 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 time. 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 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 signal to control linear actuator position and correct for disturbances. 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 to reach the desired outcome. Our potentiometers found in PA-14P (see below) 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 Actuators
The uses for a linear actuator with feedback can be found in a variety of different applications. Some examples include home automation, prototyping, and robotics.
Automated Window Demo
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 overextend and crack the windows if the stroke length is slightly too long to fit. See the video below of a demo automated window setup.
Human Powered Vehicle
One of our sponsored projects, which utilized a linear actuator with potentiometer feedback, is 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 to maximize the efficiency of the prototype human-powered vehicle.
A high-speed linear actuator with feedback is used in this project. The linear actuator with potentiometer feedback 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.
See the full build here: Instructables
To summarize, a linear actuator with 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 firstname.lastname@example.org.