Not sure I understand it right. It will take some more thinking to grasp the idea.

In the actual circuit it will be a potentiometer for position control of a motor at the other end. The feedback provided by the motor's potentiometer.

Got it finally! Insomnia helps sometimes. What you called "input" is Vref in my book; there goes the potentiometer's taper.
Good luck.

 

I didn’t like the textbook frequency response of the PID controls so I designed a circuit to help it react faster

standard PID


with my circuitry added


the PCB design is finished. It’s all THT with large potentiometers which will be mounted on a panel and wired. I‘m letting the design sit for a week or so, I might want to add an LED and test points for attaching probes.

 

Just a follow up here’s my project on the test bench...

took me a couple days to work out some inversion issues but ready to present it this Wednesday.

The perfect enclosure was an recent gift from our janitor when they switched to LED Exit signs in our building.

 

Here's the video, we presented last night... all done til next fall, I plan on taking some digital courses it will get me started in FPGA using VHDL and get me more familiarized with PIC... which I'm not sure is an improvement on the AVRs. It seems that the AVRs are faster.

From left to right:

Control, kp, ki, kd and my own little circuit I call kphi which removes phase inversion and speeds up response. The two toggle switches are for adding or removing kd and kphi for testing purposes.

I will be building a little power supply so I can directly power by AC for demonstration purposes when we resume our First Robotics club activities.

The pointer was machined on my lathe and desinged so that the pointer screws doubles as the set screw. Its attached to a motorized potentiometer for closed loop feedback. Using 7 LM358's, push pull BJTs for motor driver, running on +/- 15V draws about 240 mA peak, 40 mA typical. I added an adjustable gain stage in the summing amplifier for approximately 1-100 gain .

http://imgur.com/LdHOFF0

 

Impressive.
Could you show your updated schematic?

 

I'm sure I'll have one soon... I made a few changes while testing and haven't updated yet.

 

I think you can do the PID in one op-amp
http://yawp.com/ref-library/subjects/circuits/analog circuits/PID/PID-Radio.pdf

 

Oh that is interesting, I’ll have to work through this, it looks possible, more complicated but may be a great idea to add functionality when space is limited. Actually for something needing just PI, it might be a option. I looks like it would be difficult to adjust only one of the 3 components in use for tuning (adjusting one will affect others)

 

Wolframore;
congratulations on the successful completion of your project. You should be proud.

May I offer a suggestion? Put labels the adjustment potentiometers. On the video we can see you are tuning the response, but because the potentiometers are not labeled, we don't know what you are tweaking.

 

I started to make labels but my handwriting is so bad, I threw them away