[time-nuts] Making a HP 10811 and similar types better in the real world Part I

[Magnus Danielson]

On 09/22/2011 12:30 AM, Chuck Harris wrote:
> Perry Sandeen wrote:
>> GM List,
>> ..............................................................................The
>>
>> ovens are proportionally controlled. On start-up all ovens,
>> proportional or not,
>> will have over-shoot. Some more, some less. An inescapable fact of life.
>
> Imagine that the set point is variable, and can be set below the desired
> temperature. Then imagine that the set point can approach the desired
> temperature more closely as it gets closer to the desired temperature.
>
> ... And you will have discovered (100 years late) the PID controller.
>
> PID controllers do not have to overshoot the desired temperature. It is
> not an inescapable fact of life. 30 years ago I was designing PID
> controllers,
> with a little microprocessor magic, that could quickly arrive at the set
> point
> temperature and never, I repeat, never, exceed that temperature. Someone's
> internal organs would have become toast if it did.

Overshot is fairly easy to avoid for a well controlled PID loop simply 
by setting the damping factor properly.

PIDs is nice in that you can control loop bandwidth and damping factor 
fairly well. Overshot properties vs. damping factor is a well researched 
field and already tabulated before I was born.

Cheers,
Magnus