Self Balancing Algorithms

[Doubt]

http://en.wikipedia.org/wiki/PID_controller

ETA: http://www.eetimes.com/ContentEETimes/Documents/Embedded.com/2000/f-wescot.pdf

PID loops are the industrial standard for control. I work on heat treat furnace control systems and have set up plenty of different systems for temperature, atmosphere, pressure and speed control systems. All using discreet controllers or PLCs.

A robotic balance system will probably need the whole PID equation to stay upright. But you could get pretty close just by working with the proportional band part of it if it just needs to stand there.

 

[BushRanger]

When I was in Engineering School, I found a lot of books that talked about an "inverted pendulum," and some books included pretty detailed specifics about how to build one. Although I built a snazzy motor controller, I thought it might be kinda fun to build an inverted pendulum or other balancing apparatus, especially one that could stand up to a lot of disturbance and still not fall over. Never did, though. It would be a great science demo, and I imagine that it could be adapted interactive use in a museum of science and technology ... but I've never seen one.

you should have... our labs had one and it was very rewarding to make a controller for it.

 

[Brown]

you should have... our labs had one and it was very rewarding to make a controller for it.

There were a lot of projects I thought about building, and I didn't have the time to build them all. Among the ideas were a controller interface that would do something (e.g., change the station on a car radio) without touching the interface, and a self-balancing apparatus. I even dreamed of setting up an electronics shop in my home, where I would build various projects... but I found I did not have the time to devote to that hobby.

I did, however, build an FM transmitter implantable in a human head, a metal detector, an AM radio, and a motor controller, among a few other things. It is difficult to describe the effect of building these projects. They all involved modeling the system, doing the calculations, predicting the effects, and adjusting the model. In other words, before a single component was ever put into a "breadboard," the system was mapped out "in theory." Then the system was built and tested. And when it worked, there was always a powerful epiphany: "Hey, these theories and mathematical models ACTUALLY WORK!!"

Sometimes the results are stunning. In the case of my motor controller, the motor I set out to control was a cheap little toy motor. In order to get the thing started, you had to inject enough current to overcome the internal forces between the rotor and stator (due to magnetism and friction). Once you got the motor to run, it ran FAST. If you tried to get it to run slow, the internal forces would take over and the motor would seize and stop. Basically, the motor had two speeds: FAST and OFF.

My motor controller took me a couple of weeks to design and build, but when it got up and running, it could make the motor spin SLOW. I could make the motor spin at pretty much any speed I wanted between FAST and OFF, and I could even make it spin backwards. My only user-operated control was a dial. If I tried to disturb the system (such as by forcing the motor to do more work), the system compensated automatically. It was fanTAStic and exceptionally rewarding.