From: Sylvan Butler
Subject: Re: Heated seat controller, open or closed loop temp.control
Date: Fri, 25 Oct 2002 16:19:14 -0600
User-Agent: slrn/0.9.7.3 (Linux)
On 25 Oct 2002 14:41:14 -0700, john jardine wrote:
> "Jeroen" wrote in message news:...
>> I'm making a controller for my heated seats in my car, and still havn't made
>> a decision whether it should be a closed or open loop temp control. It will
>> have 4 settings. In openloop that would simply be 25,50,75 and 100% output
> For simplicity and sanity, keep it open loop.
> If you go for closed loop then be prepared to implement (and tune) a 3
> term PID control sytem.
Why??? A simple thermostat is closed loop.
> The heater has a significant time lag to setpoint and this creates all
> the control problems.
> Do you really need +/- .5degC control ;-).
Trying for that level of control is what creates control problems.
A simple closed loop which maintains temperature at a setpoint +/-
several degrees is not complex.
| Sylvan Butler | Not speaking for Hewlett-Packard | sbutler-boi.hp.com |
| Watch out for my e-mail address. Thank UCE. >>>> change ^ to @ <<<< |
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