As others have said, this page provided more understanding than more than one university course I've taken. Oh, and anecdotally I'll state that while Ziegler-N

As others have said, this page provided more understanding than more than one university course I've taken. Oh, and anecdotally I'll state that while Ziegler-Nicholls was great for my lab exercises, it was, ahem, quickly dropped when I started tuning heavy lifting equipment. Increasing proportional gain until stable oscillation was achieved with 160 metric tons in the test tower outside was, ahem, not boring. Not in the least.