In which type of control action does the controller's movement rate depend on the deviation from the set-point?

Proportional control is characterized by a direct relationship between the control action and the deviation from a set-point. This means that the greater the difference between the desired value (the set-point) and the actual value (the process variable), the more the controller will activate to correct the error. Essentially, if the system is significantly off from the target, the controller will respond with a larger output to reduce that deviation.

In a proportional control system, the control action maintains a proportionate response to the error, which helps to stabilize the system and bring it back to the set-point efficiently. This method is widely used in various applications because it provides a simple and effective means of control.

Other control types contribute differently; for instance, integral control focuses on the accumulation of past errors, while derivative control reacts to the rate at which the error changes, and feedforward control anticipates changes based on external inputs rather than reacting to discrepancies.