What is "proportional-derivative control"?

Proportional-derivative control is a control strategy that combines two elements: proportional response and derivative action. The proportional component adjusts the output based on the current error or the difference between the desired setpoint and the process variable. This means it reacts to the current state of the system, providing a corrective action that is proportional to the size of the error.

The derivative part, on the other hand, anticipates future behavior based on the rate of change of the error. By calculating how fast the error is changing, derivative control can help predict future errors, allowing for quicker adjustments to the control output. This combination helps improve system stability and response time, often leading to reduced overshoot and settling time in the control system.

This approach is particularly effective in systems where fast response is critical, and it can help mitigate issues like oscillations by providing a damping effect through the derivative action. In essence, proportional-derivative control is about leveraging both current and predicted error behaviors to enhance overall system performance.