The VEX Potentiometer V2 is a sensor that measures the rotational position of a shaft by providing a variable voltage signal. It offers higher durability, reliability, and precision compared to previous potentiometer model.
How the Potentiometer V2 Works
A potentiometer is an analog variable resistor. It produces a voltage output that varies based on the position of an internal wiper arm moving across a resistive material. As the shaft rotates, the wiper arm sweeps across the resistive track, changing the resistance and therefore the voltage output.
The Potentiometer V2 uses a conductive plastic resistive track rather than a traditional mechanical resistive material. This provides smoother operation, reduces wear, and extends the sensor’s life. The sensor produces an analog voltage that is read by an EXP Brain 3-Wire Port and converted into a digital value between 0 and 4095.
A potentiometer also contains a region called the deadband, where no resistive material is present. If the wiper arm moves into this area, the circuit becomes open, and the sensor outputs 0 volts. The Potentiometer V2 is designed to minimize deadband effects, allowing for more consistent readings.
Many common potentiometers, such as those used for volume knobs or light dimmers, use a fixed shaft to adjust resistance as it turns. These designs often rely on frictional contact with resistive materials that can wear down over time.
In fixed-shaft potentiometers, the rotation of the shaft directly moves the wiper across the resistive track. Over time, mechanical wear can lead to inconsistent readings or sensor failure.
The VEX Potentiometer V2 uses a through-hole design rather than a fixed shaft. A square shaft passes through the center hole, allowing rotation to be measured without restricting mounting options. This design provides flexible integration into a variety of mechanisms while maintaining durability and accuracy.
Common Uses for a Potentiometer V2
Potentiometers are commonly used for two main applications: controlling the position of an assembly or providing varying feedback to a system to select a function or change a variable value.
Controlling position: A potentiometer can be attached to a rotating shaft on a mechanical structure to provide position feedback. For example, a sensor could be mounted to monitor the position of an arm mechanism. Using feedback from the sensor, a control system could be programmed to move, stop, and hold the arm at specific positions when certain inputs are triggered.
Adjusting variables or functions: A simple assembly, such as a knob attached to the potentiometer shaft, can be used to adjust a variable within a program. Each time the system is run, the value read from the potentiometer could determine how much a mechanism moves or how a particular action is executed.
Another example is to divide the potentiometer's output range into several segments, where each range triggers a different function or message when selected. For instance, turning the knob to different positions could change what message is displayed on a user interface.
For a guide on how to configure the Potentiometer V2 as a 3-Wire Device, go here.