Reply-To: "Fred Bartoli"
From: "Fred Bartoli"
Subject: Re: Heated seat controller, open or closed loop temp.control
Date: Sat, 26 Oct 2002 00:12:58 +0200
X-Newsreader: Microsoft Outlook Express 5.00.2919.5600
Organization: Guest of ProXad - France
NNTP-Posting-Date: 26 Oct 2002 00:11:26 MEST
"john jardine" a écrit dans le message news:
> "Jeroen" wrote in message
> > Hi,
> > I'm making a controller for my heated seats in my car, and still havn't
> > a decision whether it should be a closed or open loop temp control. It
> > have 4 settings. In openloop that would simply be 25,50,75 and 100%
> > (simply low freq PWM, period 1 second or so) or in closed loop for
> > 35,40,45,50 deg C.
> > I once made a version that would go one setting down each 3 minutes
> > reaches setting 1 at which it will remain then (until you choose another
> > one). You could also stop that by pressing the button a little longer.
> > I think a simple on/off controller would do, no fancy PID stuff.
> > Jeroen
> 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.
> The heater has a significant time lag to setpoint and this creates all
> control problems. Do you really need +/- .5degC control ;-).
Not accounting for the fact that he'll have to "carefully" place the sensor.