Recent content by pnachtwey

It depends on the units of Ki. Ki would need to have units of 1/time or be an inverse time constant to be correct. Ki should be replaced by 1/Ti. This way the time units cancel out. Ki implies it is a gain and not a time constant. This is not a normal way of expressing a PID controller but...

You can't control two things at once exactly. What you need to do is have a cost function and minimize that. What error can you tollerate the most or least?

So why don't you name one? Yes, so why have multiple sensors if you can't tell which one(s) are bad? We use model based control when necessary. Model based control can estimate the true acceleration more accurately than just taking the second derivative of quantized position data.

If the controller gain by the P and D terms then the P and D terms are expressed as time constants, not gains. The plants don't need to be linear if you have the formulas as a function of the plant parameters. Then the gains can be changed as the plant changes. This video shows how to control...

If you are asking if the individual PID gains can be changed independently, they can. However, there are fomulas for calculating the each of the PID gains that use the closed loop pole locations to calculate the controller gains, P, I and D. For instance, if I tune a small motor in torque...

What you call process times, I call settling time. It would be nice if you provided a link to the PID manual to reduce the number of questions. I need units that make sense. The two gains should be working at the same time like in my PDF. The integral gain will cause the process variable to...

What do you mean by the end of each process loop time. This doesn't make sense. Below is a link to an example PI control for a heat exchanger. It was a contribution to the www.controlguru.com website way back in 2005. I show how the IMC PI gain are derived. Everything is shown. Mathcad -...

The system is a dual loop PD controller with an inner velocity gain and an outer proportional gain The output of the Kp term is intended to be a reference for the velocity loop. This system is very simplistic. It isn't clear what the author is trying to do with the pulses. The output from...

Ditto, about knowing the application. Servo motors and servo hydraulics have different strengths and weaknesses. I would also like to add that the design is often flawed. My company makes servo controllers. We specialize in hydraulic servo control. Everyone has been predicting the doom of...

I go way back. Do you remember modems? I use to use x-modem, y-modem and even Kermit. These modem protocols were simple and not timing dependent. Back when there were Bulletin Board Services your modem had to connect withe the BBS modem. This usually wasn't a problem. The modem protocols...

That website is so basic and misleading because it is so basic. Too many try to teach control by saying this gain doe this and that gain does that without really understanding what the controller gains do. The "teachers" teach what they have been taught even at a college level. In reality...

Jams22 was lucky. He can't prove otherwise. He can't provide units or what the range should be. This thread should be deleted to avoid misleading others that aren't knowledgeable about control theory.

Again, you are lucky and you haven't answered the questions. What is a 1/3 of a range? What range? How do you know a derivative gain is even necessary? In your example of moving .75 m/s a derivative gain is not necessary. The system can be modeled as an open loop gain or a time constant or...

Yes! You don't even have units! Is I a gains or a time constant? In motion control we use gains instead of time constants most of the time. It depends on the system and whether you are trying to control position or velocity. The derivative is too high relative to the P and I gains for most...

Yes, but you probably won't like them. Why are you doing this? It is a waste of time doing it your way. What do you hope to achieve? No one would try this like what is suggested for a real system. The control is going to be very "mushy". A lot of energy is going to go into compressing the...