Interesting,… what I was looking for was some infomation on the Last Planner System™ and Hals comments in blog of Wednesday, October 02, 2002 First Thoughts on Control were both along the lines of what I was looking for and it got me thinking progressivly towards some other ends too. Talking about Kevin Kelly and his book Out of Control: The New Biology of Machines, Social Systems and the Economic World 
“Kevin traces the development of modern control to Norbert Weiner. Young Norbert was raised to be a genius. His father wanted a Nobel Prize in the family. His work provided the foundation for cybernetics. It started when he joined the effort to make uniformly thick sheet metal. The stakes were high because uniform feedstock would allow machines to make car parts — fenders, auto bodies etc. Three variables were obviously involved – the heat of the metal, the pull tension and the roller setting. But no one had found the magic relationship that could assure a long uniformly thick roll. Norbert cut through the problem. He showed with a simple mechanism that controlled the last variable produced the desired result as long as the other variables were within in a range. Being “right” didn’t matter as much as the ability to adjust quickly. His device detected the thickness of the metal just past the rollers adjusted them in response. Controlling the last variable with rapid feedback was all that was required as long as the other variables were within some range.
I was struck by how well the Last Planner System™conformed to this rule. Work is made ready as it moves forward to action and only released to certain criteria….
…There is more to say about control of more complex systems but the first rules are clear. Control the last variable while keeping the others within some range, and tightly couple the detection of variance to the control gate.” (my emphases)
More good stuff and very apropos. Just the kind of stuff I was looking for today.
