How can I use active filters to control a balancing robot project using LabVIEW?

[LabGuy330]

Hey everyone,

I want to make a a simplified "segway" project. I plan on using a servo motor with a wheel attached and attaching a breadboard to act as a inverted pendulum. My idea is to use LabVIEW to generate the PWM for the servo and (instead of using LabVIEW PID) use active filters to act as a PID controller. I would be using a simple tilt sensor for inclination.

This is my first "robotics" project and I was looking for some advice. I am unsure exactly how to set everything up. I know from a controls systems class I have taken that the error signal is the input to the PID controller (in my case the filters) and outputs a calculated voltage. Should this calculated voltage be an input to my LabVIEW assembly for generating a propper PWM for the servo? If so any advice on achieving this?

My knowledge of electronics is somewhat limited, however I am very interested in the field. My LabVIEW skills aren't excellent either so any help would be greatly appreciated.

Thanks in advance!

 

[256bits]

Here is what someone else did:
http://web.mit.edu/first/segway/#electronics

And another with alalog control from a guy at MIT
http://www.etotheipiplusone.net/?page_id=566

 

[Allenman]

http://www.instructables.com/id/Easy-build-self-balancing-skateboardrobotsegway-/?ALLSTEPS

 

[LabGuy330]

Hey thanks for the replies!

Those links/videos are impressive. My project won't be as sophisticated (just a smaller scale). My idea is to basically have a balancing toy, something small for a simple lab project. Something similar would be like this:

http://www.youtube.com/watch?v=bdNxgCsWB5E"

I do not plan on using his methods however (he uses LDRs and a 555 timer). I want the lab to get an understanding of PID control through active filters. I have attached a simple schematic for it along with a block diagram.

Key for Block Diagram:
R(s) = Reference or desired angle (0 degrees so 0 V)
C(s) = Controller (PID through the active filters)
LV = LabVIEW (calculates PWM)
M(s) = Motor (outputs wheel rotation)
P(s) = Plant or dynamics of the inverted pendulum

I am using three op amps for PID control, proportional gain through one amplifier, integral control through integrator (low pass) amplifier, and derivative control through differentiator (high pass) amplifier. These signals are then summed to a summing amplifier which is at the far right of my schematic and outputs to LabVIEW to calculate the PWM for the motor.

Not sure how robust this idea is (I am a ME undergrad w/ limited mechatronics knowledge). If anyone has experience or any input with something like this I would love some feedback.

Thanks in advance!