What are some examples of control systems that require high sensitivity or high robustness or both?

2 PID controller

A PID controller is a common type of control system that uses proportional, integral, and derivative actions to adjust the input of a system based on the error between the desired and the actual output. PID controllers are widely used in industrial, engineering, and scientific applications, such as temperature control, motor control, robotics, and process control. PID controllers require high sensitivity because they need to minimize the error and achieve the desired output as fast and as accurately as possible. If the PID controller is too insensitive, it may cause the system to be sluggish, overshoot, or have a steady-state error. However, PID controllers also require high robustness because they need to cope with uncertainty and variability in the system dynamics, the measurement noise, and the external disturbances. If the PID controller is too sensitive, it may cause the system to be unstable, oscillate, or amplify the noise.

3 Flight control

Flight control is a control system that controls the attitude, altitude, speed, and direction of an aircraft by adjusting the aerodynamic surfaces, such as the wings, the tail, and the rudder. Flight control requires high sensitivity because it needs to respond quickly and precisely to the pilot's input, the air pressure, the wind, and the gravity. If the flight control is too insensitive, it may cause the aircraft to be unresponsive, sluggish, or deviate from the desired trajectory. However, flight control also requires high robustness because it needs to work reliably and safely in different flight conditions, different aircraft models, and different failure scenarios. If the flight control is too sensitive, it may cause the aircraft to be unstable, oscillate, or experience excessive stress.

4 Insulin pump

An insulin pump is a control system that delivers insulin to a diabetic patient by monitoring the blood glucose level and adjusting the insulin dose accordingly. An insulin pump requires high sensitivity because it needs to maintain the blood glucose level within a narrow range that is optimal for the patient's health and well-being. If the insulin pump is too insensitive, it may cause the blood glucose level to fluctuate too much, which can lead to hyperglycemia or hypoglycemia, both of which can have serious consequences. On the other hand, an insulin pump also requires high robustness because it needs to adapt to different factors that affect the blood glucose level, such as the food intake, the physical activity, the stress, and the illness. If the insulin pump is too sensitive, it may cause the insulin dose to vary too much, which can also lead to hyperglycemia or hypoglycemia, or cause other complications.

5 Active noise cancellation

Active noise cancellation is a control system that reduces unwanted noise by generating an opposite sound wave that cancels out the original noise. Active noise cancellation is used in headphones, earphones, microphones, and other devices to improve the quality of sound and reduce the interference from the environment. Active noise cancellation requires high sensitivity because it needs to detect and match the frequency, amplitude, and phase of the noise as accurately and as quickly as possible. If the active noise cancellation is too insensitive, it may fail to cancel out the noise completely, or introduce new noise or distortion. However, active noise cancellation also requires high robustness because it needs to work well in different noise sources, different sound levels, different locations, and different user preferences. If the active noise cancellation is too sensitive, it may cause feedback, instability, or unwanted cancellation of desired sounds.

6 Here’s what else to consider

This is a space to share examples, stories, or insights that don’t fit into any of the previous sections. What else would you like to add?