Mon Prof Augmenté
A Robot Arm That Corrects Itself
Age 17 · Technology
Open to everyone until Sunday, November 15
To keep it, print it while it is open.
In closed-loop control, a sensor measures what the system is actually doing and feeds that value back to a controller. The controller compares it with the target (the setpoint) and drives the actuator to shrink the difference.
In the picture
- Sensor: measures the real height of the ball
- Controller: compares the measurement with the setpoint dial and computes a correction
- Actuator (motor): moves the arm according to the correction
- Feedback cable: carries the measured output back to the controller, closing the loop
Examples
- A thermostat measures room temperature and switches the heating on or off to reach the temperature you set.
- Cruise control reads the car’s speed and adjusts the throttle to hold the speed you chose, even uphill.
Key takeaways
- Feedback lets a system correct its own error, using the gap between setpoint and measured output.
- Without the return path from sensor to controller, the system is open-loop and cannot react to disturbances.
Quiz: A Robot Arm That Corrects Itself (Age 17)
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In a closed-loop system, what does the controller compare in order to decide how to correct?
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What turns a feedback system into an open-loop system that cannot react to disturbances?
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A disturbance pushes the system away from its target. Why can a closed-loop system recover on its own?
The answers, each with its explanation, are in the app. This quiz is free there while the lesson is in the free week.
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