Recall a certain position?

Is there any way to record a certain position of a robot?

ie. if i need the robot to extend an arm out to a fixed location at any point in time?

Thought about using a timer function and just to kick the motor on for a certain time, but due to the nature of how the robot operates, the arm could be anywhere so a timer would not work as the arm could be in any range of motion.

Any ideas?


X,Y position of robot on the field is often difficult, but wheel encoders help.
Theta position of the arm of a robot is easily done by using a potentiometer.
Lots of previous threads about this, including PID loops, or just P .

Its called “open loop” when you run motor for a certain time.
Its called “closed loop” when you have feedback from system the motor is moving.
See also “control system theory”