So how many people in the technic forum use mindstorms and what for? Killer robots, theme park rides or the usual brick sorter?

Mine sits in it's box most of the time!

But I have made Lego Cows using the designs online where their heads move when the sensor is activated,

Any pictures and why a cow, somes cool!

But I have made Lego Cows using the designs online where their heads move when the sensor is activated,

Now that really sounds like a killer robot!

But I like to see a picture of it too....

These aren't my cows, but I nicked the idea, built 10 of them and copied down the guy's programming,

but you get the idea of what mine do x 5

http://www.youtube.com/watch?v=KxL3VL3gHag

These aren't my cows, but I nicked the idea, built 10 of them and copied down the guy's programming,

but you get the idea of what mine do x 5

http://www.youtube.com/watch?v=KxL3VL3gHag

Burf2000, where are you from, hampshire sounds close to me, I'm in Aldershot

So how many people in the technic forum use mindstorms and what for? Killer robots, theme park rides or the usual brick sorter?

I'd like to recognise trains as they pass (using an RFID sensor if I can hide a 4x4 round tag on each train to pass within 3cm of the sensor).

The program would then play sounds corresponding to the signal box bell codes for accepting the train and would set the speed of the PF trains with an IR Link sensor.

Several NXTs would do the same at different points in the layout (only one doing bell code sounds). One NXT would ensure that trains went slowly enough not to derail in the (unreachable) fiddle yard and another would set maximum power for going up a 1 in 30 slope.

I plan to test it soon, as soon as I've bought all the remaining parts. I've had success with the NXT commanding a PF IR receiver before.

The test will check feasibility, especially for the 3cm distance relative to train loading gauge clearances (i.e. I have to mount the sesor on a straight piece of track, not a curve, to get a consistent distance). Feasibility at train speed will also need testing - can the sensor detect the tag fast enough as the train passes? If it works, I'll buy more RFID sensors and tags.

BTW my modular 16ft x 12ft railway layout can now run trains round the outer circuit (after 4.5 years of building!). This includes a PF hybrid loco, which makes a good test of the PF electric system capability for other high power applications too. Some of the points are pneumatically-actuated and others use PF medium motors.

Mark

I'd like to recognise trains as they pass (using an RFID sensor if I can hide a 4x4 round tag on each train to pass within 3cm of the sensor).

The program would then play sounds corresponding to the signal box bell codes for accepting the train and would set the speed of the PF trains with an IR Link sensor.

Several NXTs would do the same at different points in the layout (only one doing bell code sounds). One NXT would ensure that trains went slowly enough not to derail in the (unreachable) fiddle yard and another would set maximum power for going up a 1 in 30 slope.

I plan to test it soon, as soon as I've bought all the remaining parts. I've had success with the NXT commanding a PF IR receiver before.

The test will check feasibility, especially for the 3cm distance relative to train loading gauge clearances (i.e. I have to mount the sesor on a straight piece of track, not a curve, to get a consistent distance). Feasibility at train speed will also need testing - can the sensor detect the tag fast enough as the train passes? If it works, I'll buy more RFID sensors and tags.

Mark,

Surely Tags Beneath the trains would be best both for visibly and distance.. however mounting the sensor beneath the track would mean between tables or in a bridge abutment.

P.

Mark,

Surely Tags Beneath the trains would be best both for visibly and distance.. however mounting the sensor beneath the track would mean between tables or in a bridge abutment.

P.

I have some sections of track far enough off the table (up to 49 plates up, to pass over other tracks), but it's not in every place where I would want to change train speed. I need:

Max power up the hill. This is at table height.

Min power down the hill. This could be done at the top of the down hill.

Medium power through the station. This could be done at the top of the up hill.

Medium or low power through the fiddle yard, to minimise derailments. This is all at table height.

I toyed with the idea of raising everything up some more, but it would be a lot more bricks for modules covering 450 x 600 studs!

It would have to be about 6 bricks to accommodate the sensor facing upwards.

Mark

I'd like to recognise trains as they pass (using an RFID sensor if I can hide a 4x4 round tag on each train to pass within 3cm of the sensor).

I'm interested to see how the RFID works for you in this application, it is a very nice sensor. It should be feasible to see the tag if the train slows down. I used RFID in an ATM Machine

, but for that the RFID card is moved into position and stopped directly over the sensor - likely a bit easier than seeing it in a moving train.

Edited October 6, 200915 yr by ronmcrae

I'm interested to see how the RFID works for you in this application, it is a very nice sensor. It should be feasible to see the tag if the train slows down. I used RFID in an

, but for that the RFID card is moved into position and stopped directly over the sensor - likely a bit easier than seeing it in a moving train.

I'd better get on and order it

I'd like to hide the tag in the train. I notice it's like a 4x4 dish with an extra bit for the peg attachment, so that's too big to fit behind a 1x4x3 panel. Therefore it'll have to be behind a layer of 1-wide bricks.

Given the 30mm range, will it work through 2 or 3 layers of 1-wide bricks?

Mark

I'd like to hide the tag in the train. I notice it's like a 4x4 dish with an extra bit for the peg attachment, so that's too big to fit behind a 1x4x3 panel. Therefore it'll have to be behind a layer of 1-wide bricks.

Given the 30mm range, will it work through 2 or 3 layers of 1-wide bricks?

The clear plastic disc is quite a bit smaller than the keychain tag so it would fit inside a 1x4x3 panel. I tested one simply taped inside a train car behind a 1-wide sidewall of bricks. The sensor detected the disc quite easily when the car moved past it at a reasonable speed.

Now thats cool, does it do anything?

Now thats cool, does it do anything?

Yes, fully functional. I've made the clickable link to youtube a bit more intuitive in the original post.

The clear plastic disc is quite a bit smaller than the keychain tag so it would fit inside a 1x4x3 panel. I tested one simply taped inside a train car behind a 1-wide sidewall of bricks. The sensor detected the disc quite easily when the car moved past it at a reasonable speed.

That's good, though they're not so easily available to normal UK methods of payment. I saw them on the Codatex website. They're 22mm so yes they will fit in a 1x4x3 panel because a 3-wide brick fits there too.

I'll also need an NXT sensor socket-to-socket extension so I can install sensors in a modular layout with wires trapped under tracks on each side of the detachable module boundary. I suggested it to HiTechnic as they make extra leads and multiplexers already. A 4-way sensor multiplexer wouldn't fit between 2 train tracks by the time the leads are plugged in.

Mark

That's good, though they're not so easily available to normal UK methods of payment.

Can't you just order them on a credit card? I did that from USA and was amazed when everything showed up exactly two days later by Fedex directly from Austria. Very impressive service.

I'll also need an NXT sensor socket-to-socket extension so I can install sensors in a modular layout with wires trapped under tracks on each side of the detachable module boundary.

Even if you could get an extension cable, I'm fairly sure that I2C sensors are limited to a cable length of about 1 meter. Beyond that the signals start to get a bit iffy. Could you have an NXT on each modular section? Up to four of them can be bluetoothed together.

A 4-way sensor multiplexer wouldn't fit between 2 train tracks by the time the leads are plugged in.

Isn't that what trackside building are for?

Can't you just order them on a credit card? I did that from USA and was amazed when everything showed up exactly two days later by Fedex directly from Austria. Very impressive service.

Even if you could get an extension cable, I'm fairly sure that I2C sensors are limited to a cable length of about 1 meter. Beyond that the signals start to get a bit iffy. Could you have an NXT on each modular section? Up to four of them can be bluetoothed together.

Isn't that what trackside building are for?

Maybe I will need a credit card after all. I have managed to avoid having one till now. With a debit card if you don't have the cash you can't spend it! It's probably worth having the extra credit card protection for online payments anyway. This may happen after I have tested the theory with the sensor from LS@H. I have to decide what part of the train to put the tag or disc on.

In the train roof would be good because underneath tracks can have the sensor suspended above them. Visible tracks need a gantry as an excuse, with some black tape round the sensor, but that's OK. If the RFID will go thoguh 1-wide bricks than a train roof should be OK too, plus all the trains are the same height but not the same width.

I have also considered that the bell codes for a loco will need to change depending on whether it is pulling a train or running light engine. I might put 1 tag in the loco and another in the train itself. The loco tag would trigger the single "ding" that wakes up the next signalman, to which he responds with a single "ding" (a different tone from the same NXT). The train tag could be in the last truck or carriage so that if it were not detected within a few seconds, due to a decoupling accident, the bell codes would sound for "light engine", telling me the train had broken before the loco ran round the layout and hit the back of the train! Otherwise the train tag would dictate the bell code, perhaps 3-1 for a passenger train or various ones for freight trains, depending on the type of load and whether the train has continuous brakes. The train code would be repeated by the next signalman (at the different tone) and the twin "ding-ding" for Train Entering Section would follow (maybe the NXT could also drive a gauge showing "Line Clear"). I have books on signalling that give a list of codes. I guess it will require some practice to get right but I've seen model railway enthusiasts running a layout with proper signal box operation before.

I hear from HiTechnic that I2C is limited to 90cm, which (surprise surprise!) is the longest lead they make!

Bluetooth is an option, yes. I had considered the need for 4 NXTs as there are 4 places on each circuit where I would want to change train speed, two of which would also need the signal boxes to communicate, making the bell code sounds before the train enters or leaves the viewable section. Each position on each line would need an RFID sensor and an IR Link sensor for PF trains, a total of 16 ports, just right for 4 NXTs given that a multiplexer can't fit between tracks. If the module gaps could be bridged detachably, I could try having an NXT per signal box, sending a Bluetooth code to the next NXT whenever it sounded a bell code.

I have corner hills that could house NXTs on the outer circuit and space under the yards that could house the inner circuit ones. Not so many buildings though! Some layouts have lots of town with a train. My layout is the opposite - realistic trackbed up to 9 tracks wide with a small amount of hopefully-good scenery, more in keeping with model railway show layouts of other scales and gauges. It would have been nice to see the NXT screens, but the tables are 1200mm wide, which is more than the 90cm of I2C!

Mark

Old thread, but I make a new reply here anyway.

I have now tested the LEGO RFID sensor and keyfob (transponders) with the Mindstorm NXT and a PF train.

My goal was to do what some here want to do: make a automatic train control system based on type of train where the type is set by which transponder id the train has.

I have made a simple program that just make a sound when the correct RFID is read and then goes back to constantly read for new RFID.

Just for the test I have mounted the transponder on the side of the train with just a technic friction pin so it hangs flat on the side. The sensor is mounted on a platform on the side of the track so that the transponder almost touch the sensor when it passes (have tried with different distances too).

The train is just the locomotive from the LEGO set "7939: Cargo Train" with just one PF trainmotor, no wagons and fresh batteries.

But the problem is that I can't get it to read the stable at speed 3, have to put on some heavy wagons to slow it down or set it to speed 2 to get a stable reading.

I have tried taking of the housing of the sensor so the coil is under 1mm from the transponder.

I have found out that the transpoders black side (at least on the three transponders I have testet) towards the sensor gives best result.

Also having the center of the transponder passing exactly over the ferrite core (the black rod you can see inside the housing, that goes through a coil), gives best result.

Maybe the NXT brick is too slow to read it any faster?

I use the latest LEGO firmware on the NXT and the NXT-G program to make the code. But maybe there are other firmwares/programs that can make it read faster?

I also have an Mindstorm EV3 but cant find any driver for the RFID sensor. Anyone knows how to fix that?

Maybe the NXT brick is too slow to read it any faster?

as I know for 125 kHz freq. RFID (Unique) time for 1 reading is aprox. 0.5 sec.

I don't do much with mindstorms lately .... but my son does. I've moved on to the Lego Control Interface with 16 ports total ... 8 sensors and 8 outputs ... real nice.

Edited March 25, 201410 yr by DrJB

Here is what I've created for a little Home Improvement competition at LUGPol. Very simple construction and programming but it does its job pretty nice :) And people enjoy it very much during exhibitions.

I have loads of Mindstorms stuff, but I don't do nearly enough with it to justify the amount of cash spent on all of the components.

I have a half built Wall-e like EV3 robot, which I really need to finish. However, I find myself seriously lacking the time to do some proper building. But I will definitely finish this bad boy in order to do some programming for it.