LEGO SYSTEM Trains : 3371


Trains / 3371	3370 \| 3372

Subject:	Design wanted: Touch sensor for passing trains
Newsgroups:	lugnet.robotics, lugnet.trains
Date:	Wed, 29 Dec 1999 02:08:05 GMT
Viewed:	35 times

I'm using Mindstorms to control Lego trains. Does anyone have a design for using a touch sensor to detect a train passing? My intuition is that the touch sensor could be more reliable than the light sensor (plus I have two touch sensors and only one light sensor). Thanks much for any help, Carl Kadie

Message has 7 Replies:

		Re: Design wanted: Touch sensor for passing trains
(...) I don't have a design, but I do have a comment, to wit: With a touch sensor you are committing to a fixed dimension SOMEWHERE unless you get quite clever. It may be in the width of the vehicle, it may be in the height, it may be the depth of (...) (25 years ago, 29-Dec-99, to lugnet.robotics, lugnet.trains)

		Re: Design wanted: Touch sensor for passing trains
FWIW I haven't tried this yet myself, but its very typical to use light sensors for this sort of thing in HO scale model railroading. There are a lot of advantages to "contactless" detection. On the down side, you need to minimize interference from (...) (25 years ago, 29-Dec-99, to lugnet.robotics, lugnet.trains)

		Re: Design wanted: Touch sensor for passing trains
I've never actually done it myself, but if you're interested in building your own sensor you might want to look into using a reed switch. They detect magnetic fields, so if you put a small magnet at the head of the passing train in a place such that (...) (25 years ago, 29-Dec-99, to lugnet.robotics)

		Re: Design wanted: Touch sensor for passing trains
(...) My suggestion: Touch: Have the track elevated, and free to move up and down (1 'hinged' joint). Then have your touch sensor below the track. Light: Hard to get accurate, repeatable measurements. If light level changes, requires recalibration. (...) (25 years ago, 29-Dec-99, to lugnet.robotics, lugnet.trains)

		Re: Design wanted: Touch sensor for passing trains
(...) Hi Carl, I tried some time ago, way before the mindstorms, to use read contacts. The magnets of the wagon/engines will close the contact each time they pass. I guess that the RCX can see this as 0 and 1. With this you can, I imagine, count the (...) (25 years ago, 29-Dec-99, to lugnet.robotics, lugnet.trains)

		Re: Design wanted: Touch sensor for passing trains
"Carl M. Kadie" <carlk@msn.com> wrote in message news:FnHCMC.KzF@lugnet.com... (...) Thanks for all the suggestions. I've refined my goals a bit: I'd like to use just Lego parts. I don't mind of the sensor is conspicuous. I don't mind modifying the (...) (25 years ago, 29-Dec-99, to lugnet.robotics, lugnet.trains)

		Re: Design wanted: Touch sensor for passing trains
Carl- We designed some that worked very well with the 4561 Railway Express sets that we used for the Orange County Festival of Trees earlier this month. The mechanism uses one of those 5 sided aircraft wing pieces held horizontally flat near the (...) (25 years ago, 30-Dec-99, to lugnet.robotics)

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