Potentiometer
From FIRSTwiki
A potentiometer, also called a pot, is an analog sensor that changes resistance in proportion to the position of its shaft. Potentiometers can found in rotary or linear varieties. In a rotary potentiometer, the shaft rotates and causes the change in resistance. In a linear (or slide) potentiometer, the shaft moves in a straight line. Potentiometers can also come in audio or linear tapers. The audio taper means that the output varies logarithmically with the position of the shaft, and is usefull for volume knobs in audio equipment. In linear taper pots, the output varies linearly. The concept of tapers and shaft arrangments are independent, a linear potentiometer can have a audio taper, and vice versa.
In FIRST Robotics, when wiring the pot, one end of the potentiometer is connected to 5V and the other end to ground. The sense line is connected to the analog input on the Robot Controller. Thus, the potentiometer acts as a voltage divider, where the values of the two resistors can be varied.
Potentiometers are used, therefore, to determine where specific moving parts are in their range of travel on the robot, or to provide analog input to the Operator Interface.
Note that when working with analog values on the 2004 Robot Controller, the function Get_Analog_Value must first be called. This is not necessary when the pot is connected to the Operator Interface.
