Lab 1 - Empirical PID Control

Welcome to laboratory exercise 1! In this exercise, you will get a feel for how a PID controller works, and how adjusting the different controller parameters affects the control performance. This aims to give you some intuition for the theory you have started to learn about, and to help you better understand how things are connected, and what trade-offs have to be done when designing a controller. In this exercise, you will try to select good PID-parameters empirically. In lab exercise 2, you will solve the same problem (PID control of the same process), but using a more systematic method for selecting the controller parameters. You will then be able to compare these different approaches.

Prerequisites: You are recommended to watch lectures 1 and 2 (or read chapters 1 and 2 in the course compendium) before doing this exercise.

The exercise consists of three parts:

1. Go through the lab manual [lab1_manual_Swedish / lab1_manual_English] and solve the assignments, using either the simulation or the video described below.
2. Answer the following quiz: [mandatory quiz for lab 1]. The passing grade for the quiz and the number of attempts are stated in the quiz.
3. Attend a 15-minute discussion session on Zoom with a few other students and a TA, to discuss important concepts and results from the exercise. You can sign up for this below, between the stated dates. A list with examples of questions that might be discussed is found here: [lab1_questions_Swedish / lab1_questions_English]. This list might be good to go through and think about in order to check that you have understood the main points of the exercise.

Note that you must have passed the quiz before attending your discussion session, and that you must attend a discussion session in order to pass the exercise.

Since the exercise is carried out remotely, you cannot use the physical processes for solving the lab assignments. Therefore, we offer you two different alternatives for this: You can either use a simulation of the process, or you can watch a video demonstration of the tasks on the real process. (You can of course also do both, if you want.) We recommend you to choose the simulation option, since this will allow you play around with the parameters for yourself, which should give you a better understanding and intuition for the important concepts and how they are connected. The options are described below.

If you have any questions about the lab assignments, you are welcome to discuss them with us at the exercise sessions.

Sign-up

The sign-up for the discussion sessions can be found by going to the Calendar and then clicking on "Find Appointment" to the right. You must sign up at latest Fri 29 Jan (course week 2). The discussions will take place between Mon 1 Feb and Mon 5 Feb (course week 3) in the following Zoom meeting: https://lu-se.zoom.us/j/62164622370.

Option 1: Simulation

You can solve the assignments in the manual by using the simulation of the process and controller, which looks like this:

The simulation is a Matlab script, which can be downloaded here: tank_sim.m Instructions of how to get it working are given below:

1. If you don't have Matlab installed on your computer, download it from here: Software LTH and install it.
2. Download the simulation script file tank_sim.m and open it in Matlab.
3. Make sure that the file path  is set to where you saved the script file.
4. Click the "Run" button.

If any problems appear, you can try to close the window and run the script again.

Speed-up option

With the buttons "2x Speed" and "3x Speed", you can speed up the simulation 2 or 3 times. If you activate both at the same time, you will speed it up 6 times.

Option 2: Video demonstration

The video demonstrates some of the assignments in the exercise. It is important that you use the lab manual to follow the video.