Feedback Loop in Robotics

What is it?

A feedback loop is a control structure where the system measures its own output, compares it with a target (the setpoint), computes the error, and feeds that error back into the input to drive the output toward the target. It's the backbone of every stable robotic system.

How it works

The loop has four parts: a sensor that measures the actual output, a comparator that subtracts measured from desired to compute error, a controller (often PID) that converts error into a command, and an actuator that applies the command. The cycle repeats continuously — typically hundreds to thousands of times per second — until the error is near zero.

Real-world example

A cruise-control system in a car is a feedback loop — measure speed, compare to setpoint, adjust throttle. A robotic arm holding position uses feedback at each joint. A Roomba's wall-following is a feedback loop based on side-sensor distance.

Why it matters for robotics

Open-loop systems blow up under disturbance; feedback loops self-correct. Mastering feedback is the difference between a robotics hobbyist and an engineer. Every PID tuner, ROS2 control node, and DRDO Daksh stabiliser is a feedback loop in disguise.

See also

• Pid Controller
• Closed Loop Control
• Feedback
• State Machine