Terry Davis implements a PID controller for a rocket in SimStructure: https://youtu.be/25hLohVZdME?t=207
Proportional-Integral-Derivative (PID) controllers
21–30 of 65 posts
Re: Proportional-Integral-Derivative (PID) controllers
#22Honest question: are wiki links to any technical topic post worthy now?
At least for me, it's not about the wiki link. I'm here for the comments, the stories, anecdotes, related deep Diving links and general chit chat.
If you view the link as "this is the control systems thread for today", all the upvoter make a lot more sense.
Re: Proportional-Integral-Derivative (PID) controllers
#23PIDs are great but notoriously hard to tune. They require deep insight into the underlying physical phenomena to get right. They are also rather rigid and cannot adjust well to a changing environment (temperature and humidity can fluctuate dramatically between summer and winter in some climates). Of course, no one tunes them by hand anymore for these reasons, relying instead on optimization techniques like particle s…
I wanna know more about particle swarm . Btw i tuned my line follower with a customgui/pypidtune+mujoco
Re: Proportional-Integral-Derivative (PID) controllers
#24Thanks to the advice of a colleague who had studied control theory, I once used PID controllers to manage autoscaling compute resources downstream of a lot of message queues. We used plenty of more typical autoscaling systems too, but for some workloads, PID controllers were ideal—when we had thousands of compute clusters across many queues, they minimized the state that needed to be stored between scaling system polls while effectively smoothing out the scale up/down rate to minimize resource waste and pointless whipsawing.
Re: Proportional-Integral-Derivative (PID) controllers
#25I used it in metal detector (direct frequency measurement kind). It works really well. I (and you probably too) half assed pid controllers before you even know what it is. But it makes perfect sense. Proportional part reacts to the acute difference, derivative adjusts it when your controller is already going right direction to limit overshoot, and integral part improves cases when the difference is small but persist…
Almost always a good analysis will find a control strategy which performs better than PID... But the benefit of PID is it is fairly easy to tune and works in a really wide range of situations.
And it is most of the time not overkill
Re: Proportional-Integral-Derivative (PID) controllers
#26I did a lab exercise (part of physics curriculum) with a PID controller once. It controlled a small electric motor with a small flywheel (i.e. not much inertia). We hand-tuned the parameters with potentiometers. The effect was quite impressive: the flywheel kept spinning at the same speed when we touched it, even with moderate force. It felt like there was a huge motor driving it because the RPM just wouldn't budge. It was still not hard to stop it completely (small motor after all), but it felt very stiff before that point.
Re: Proportional-Integral-Derivative (PID) controllers
#27PIDs are great but notoriously hard to tune. They require deep insight into the underlying physical phenomena to get right. They are also rather rigid and cannot adjust well to a changing environment (temperature and humidity can fluctuate dramatically between summer and winter in some climates). Of course, no one tunes them by hand anymore for these reasons, relying instead on optimization techniques like particle s…
> Of course, no one tunes them by hand anymore
in the industry, maybe. Otherwise, FRC competitions are seeing a LOT of manually tuned PIDs
Re: Proportional-Integral-Derivative (PID) controllers
#28PIDs are great but notoriously hard to tune. They require deep insight into the underlying physical phenomena to get right. They are also rather rigid and cannot adjust well to a changing environment (temperature and humidity can fluctuate dramatically between summer and winter in some climates). Of course, no one tunes them by hand anymore for these reasons, relying instead on optimization techniques like particle s…
I wanna know more about particle swarm . Btw i tuned my line follower with a customgui/pypidtune+mujoco
Re: Proportional-Integral-Derivative (PID) controllers
#29My personal exposure to the PID algorithm was my GPU fan. There is supposed to be some sort of internal fan curve to control it's speed but mine was not working, crashes everywhere. I Could still set the speed by hand. and while I was putting together a sort of hacky user space fan curve I had an epiphany. I Don't actually want a fan curve. I want to set an ideal temperature and have the computer figure out what fan speed is needed to maintain it. So I learned more about control logic than I was really prepared for and my user space fan speed script has a cute little PID controller to do just that. (technically for fan thermals you really only need a PD controller. No anticipatory preload needed. but who's counting)
I do sort of suspect a fan thermal control curve is a PID response curve written out in long hand but don't really have the math to prove it.
Re: Proportional-Integral-Derivative (PID) controllers
#30For a robotic BLDC motor velocity control application, I moved to using a linear ADRC (Active Disturbance Rejection Control) [0] controller. It is not much more complex to implement that a PID, but at least in my context it handles changing real-world environmental conditions with a correctness which I could not achieve with a PID however much I tried to tune it.
Still uses a PID for BLDC motor coil current control, as this control loop is much more predictable.
Currently using the proportional part only from a PID for position control, but this may change in the future.
[0] https://en.wikipedia.org/wiki/Active_disturbance_rejection_c... (although this isn't a very useful reference if you want the implementation maths!)