EEVacademy #6 - PID Controllers Explained

David explains PID controllers.
First part of a mini-series on control theory.

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[MarcoTedaldi]

"control theory, feedback appreciated" 😊😊😂

[MartynDavies]

00:17 "any feedback would be appreciated". Aha feedback: control theory. I see what you're doing there ;-)

[uzimonkey]

I use PID controllers in a different context: game development. You'll often have a variable you need to drive to a value, but need to do it in a kind of smooth or organic way. Instead of writing a new way to do it every single time I need to do this, I use a PID controller. This is especially useful when other things are trying to effect this value as well, as the PID controller can react and push harder toward the set point and generally won't overshoot the set point.

It is of course also very useful in physics simulations. I've made a hovercar just by making 4 "thrusters" on the bottom of the car, using the distance to the ground at that location as my setpoint and adding forces at those locations. If I were to try to program something like that, first I think it would take a while, but second I think I would end up with something a lot like a PID controller. They're just useful all over the place in gamedev.

I also like to think in simplified terms, usually I'm not doing equations and figuring things out exactly in gamedev, it's more of a "put values in until it looks right" kind of task. So imagine a cube that can only move up or down and the PID controller is controlling an upward force against gravity and we want it to hover at a certain height. P is the power, it's responsible for the majority of upward force. D is the damper, it wants to stop all movement, it's responsible for killing oscillations. I is intelligent, it'll make the small adjustments that P and D can't do, namely without I the cube will never quite get to the desired height. This is definitely not engineering, so definitely not an engineer's way of thinking about it but I think it's very useful.

[calabrese]

Very easy to follow, clear and fun explanation of what PID Theory is. Thank you David. Looking forward for the continuation of this topic. Good job!

[pacsmile]

What a nice way to explain this, i wish my teachers at college taught me like this, keep up the good work!

[Mr.Newlove]

Great video, and contrary to other comments; keep the math or even have more of it. But with some people talking about including electronics, maybe you could have used a small heater element and an Arduino to demonstrate real-time tuning? Or even auto-tuning like many 3d printers use for their heaters.

In the end a strong foundation in the theory followed by a good practical example of the implimentation is a great way to drive things home.

[kevyelyod]

I look forward to more control theory videos.

[TheHuesSciTech]

I think you missed the main point of the D term. If your oven has a lot of thermal mass, *both* the P and the I terms will suffer from overshoot. The D term is very specifically the anti-overshoot term; because it's the only one "smart" enough to see "the oven is below the target temperature, but nevertheless I'm going to vote *against* putting in more effort because it is trending up so fast that I can see it might overshoot soon". On the flip side though, it's refreshing to see a video that doesn't claim/imply that PID controllers are perfect in all scenarios; thank you for mentioning bang-bang controllers.

[Axelios]

Nice PID video. I thought I already knew everything about PID but you taught me several things I hadn't realized or come across. It was worth the 27 minutes!

[krgtim]

I hesitated to click on this video because I usually watch Dave's EEVBlog videos to slowly fall asleep, but now that I have found some time to watch it out of my usual schedule I have to say I really liked it for the educational aspect. Please make more videos like this one! Thanks!

Oh and nice touch with the picture at the end. That made me actually chuckle a little bit.

[KX]

So refreshing to see something about PID controllers on YouTube that isn't just tuning by guessing random numbers until the steady state looks OK and never checking the step response which always ends up massively overdamped (like orders of magnitude slower than it could have been).

[mrkattm]

Nice job, Controls was my elected concentration as an undergrad EE student until they introduced the State Space method at which time I changed to digital and computer design, a choice I regret. I am looking forward to this series, keep up the good work.

[lloydrmc]

Truly brilliant presentation. Relating the equations/terms to the graphs made it understandable to people like me.

[NilsRohwer]

Great video, thanks! I first saw them in flight controllers for racing drones. There you have to tune your PID's and see the results immediately! Now I really understand how and why. With the drones the P is the responsiveness of the sticks in relation to the drones movement. You want it as high as possible, the I is the drones ability to hold the angle you set it at while flying, and the D is used to dampen oscillations from too high P, however it does make the drones more sluggish. As you said, D resists change, makes sense. Tuning those quadracopters is an art, a blend of snappy controls and smooth video. I really enjoyed this!

[maniacalcactus]

Holy crap this is the boring part of the series?!? I can't wait for the rest this was incredibly interesting

[adamsfusion]

This was so cool and so enlightening. I'm just a hobbyist, but I love diving into the work of degreed professionals and seeing what kinds of things they learned in school, and these EEVacademy courses are like a treasure trove of direct info as well as info to look up later.

[laser-sj]

I spent alot of my career coding PID loops in PLCs.
Good video David :)

[colinterry]

Hey! I'm working through my Electrical Engineering degree. I thought this was honestly pretty good. I appreciate the layman explanations of control theory. I am actually taking a controls class soon, so this makes me feel better about that class. There was a bit of rambling and bouncing around, but that's fine. I do that when I explain things to newer students, lol. I also appreciate the math. It's nice to see application, so to speak, rather than just concepts. Keep up the good work! I look forward to more videos on this topic!!!

[billmoran]

Excellent! Excellent! Excellent! I learned basic control theory in college over 40 years ago. It was hard to understand just the theory. I've worked with PID controllers ranging from mechanical analog to fully digital controls for the past few decades. The best way to understand tuning is to do it hands on. It gives you a feel for the dynamics of the process and the amount of hysteresis in the loop. I can't wait to see the inverted pendulum project.
This is incredible content. Well done!

[Mrruben]

Thanks, it is a very fresh way to explain the concepts. I am less lost with this explanation I think I am going though a good path