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Subject: 
Re: Automated RT - Acceleration with RCX
Newsgroups: 
lugnet.trains
Date: 
Sun, 3 Dec 2000 08:14:53 GMT
Viewed: 
1871 times
  
> So... I've got an eastbound/westbound track. Station A, B, and C would all
> be connected to one of three outputs on the RCX. I'll figure out sensing
> later. The sections of track between the stations, which are insulated from
> the stations themselves (I'm assuming it's possible to isolate sections -
> how might I do that?), would be powered via a speed regulator at some
> constant voltage. Ideally I'd have two trains (although that's a little ways
> away; I'll likely just start up with one and see how that goes), so let's
> start at Station A.

The best type of sensor for this is the mindstorm light sensor with a LEGO
light.  You put the light sensor on one side of the track and on the other
side put the LEGO light.  (LEGO Light package #5310 cost 5.5 at S@H)  For
best result use a 1x2 brick with hole to insert the light brick and for the
light sensor.  This provides a better "beam of light" for the light sensor.
In your code use a value of 60 or more.  So if the light beam is cut, the
you can tell the RCX that a train is present.

ex.
if (Light Sensor Value >= 60) // light values of 60+ means that the light
{// sensor is NOT getting enough light becuase some object is blocking the
// lego lamp.
<stop train>

> 
> RCX Output A would accelerate the train, by presumabally ramping up the
> power output (from 0-7) at some spaced time interval between the PWM level
> shifts. A snesor would say "ok, we've cleared the platform and the train is
> on the powered section". Train proceeds on the Westbound track to station B.
> On reaching station B's block, a sensor begins the PWM rampdown to
> decelerate the train, and stop it at at that platform for some dwell. Chime.
> Accelerate train, travel until cleared of station B block onto the
> continuous voltage section... and into terminus at Station C.
> 
> Here, the train would stop, dwell, chime... then leave. Spring switches? Can
> that be done with 9V? I'm hoping so... because that'll simplify the
> direction change sequence.
> 
> So I guess I need... jeez, 8 of those clips that go from the 9V connector to
> the rails. Are those available separately as a S@H item?


You can get them thru LEGO Shop@Home.  Tehitem number is 5305.  They cost
$6.75 each.


> 
> This'll be a lot of fun if I can get this running, I'm sure. I guess the
> main question I have is how nicely do the 9V motors run with the RCX? How
> are other people doing acceleration/deceleration curves?

I've been doing collision avoidance with my lego train using RCX.  See my
website for the NQC code and more.
http://www,geocities.com/jedi_agh  (Click on mindstorms and trains)

I've tested speed up/downs with my trains and I can tell you the following.
Motors Speed        Output level of RCX
Stopped                     0
Too slow                    1
(No movement with load on engine)
Too slow                     2
(Train can move with load on engine - Load is 2 train cars.  The cars I have
tested are from the 4561 Express Train(
Medium Speed                 3
(Good for tracks with lots of curves)
Medium Speed                 4
Fast                         5
(Train may de-rail if track has too many curves back to back)
Too fast                      6
(50-75% of the time train de-rails.
Extremely fast                7
Train will derail on most (85%) of the curves



Message is in Reply To:
  Automated RT - Acceleration with RCX
 
Hello, I don't have any 9V trains; but I'll probably be geting the 4561 (Blue Express Railway) for either Birthday or Christmas (December birthdays suck!). Anyway, I'm really fascinated with ATO and subway/metro/rt technology... I've come up with a (...) (26 years ago, 2-Dec-00, to lugnet.trains)

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