Important PID Concepts | Understanding PID Control, Part 7

Brian Douglas

Now that you’ve gotten an overview of PID tuning techniques, this video moves on to discussing two important concepts in PID control: cascaded loops and discrete systems. Both concepts are fundamental to most practical control systems, and they each change the way you approach and think about your problem.

Cascaded loops occur when there are two feedback loops in your system - one nested inside the other. Cascaded loops occur in a lot of typical practical control designs. This video explains what cascaded loops are, why implementing them is beneficial, and how to tune them.

Control systems that run on digital computers are necessarily discrete systems. The second part of this video describes the differences between continuous and discrete PID controllers, how stretching the sample time of a discrete system can cause problems, and why we tend to design PID controllers in the continuous domain even when they will operate on a digital computer.