How to check if locomotive is on a curve track?

[mikezang]

I want to know if someone know how to check if a locomotive is on a curve track?

One way is to use a axle to instead of bogie pin, then put a rotation sensor around that axle so that curve track can be checked.

Does anyone have any more simple way to check locomotive on curve track?

[JopieK]

Why would you want to do that? I guess you could use a compass, gyro or acceleration sensor of course! rotation sensor is possible but then make sure left and right wheels aren't connected and check the rotation of the left and right side (if it is not equal you are in a curve).

[mikezang]

Because I am using RCX and I only have touch, light or rotation sensors...

[codefox421]

Because I am using RCX and I only have touch, light or rotation sensors...

You might look into using a differential with Technic-axle train wheels. By inverting the rotation of one wheel before it enters the differential, the differential will remain stationary when both wheels turn at the same rate. Monitoring the rotation of the differential will therefore tell you if the train is in a curve. Check out "Using Gears to Go Straight" from this Mindstorms book: http://goo.gl/mzfNZ0

[AussieJimbo]

Really interesting idea for tracking your train around the layout. It could also detect which direction a train has passed a set of points.

If RCX has a record function (like NXT) you could use this to read the initial 'map' of your layout. Otherwise it wouldn't be too difficult to create the map manually. In addition to supporting the location detection, the map could also provide for some self-calibration of the train position to account for any slippage.

For the curve detection:

- Checking rotation of inner and outer wheels/axles as per the great suggestions above,

- Go with your initial idea. Use a brick built bogey with an axle for the bogey pin and attach the rotation sensor to that,

- Use the touch detector to sense movement of the bogey or raised tiles on the track bed (This doesn't give you rotation angle or direction so is less useful but on a simple layout might give you enough data to do what you need)

Once you've got it all working you could output the train position data to a display just like a real train network control room. :-)

Looking forward to watching your progress. Good luck.

:classic:

Edited October 12, 2013 by AussieJimbo

[mikezang]

- Use the touch detector to sense movement or the bogey or raised tiles on the track bed (This doesn't give you rotation angle or direction so is less useful but on a simple layout might give you enough data to do what you need)

This is what i wondered, I tried it but no successful...

[Daedalus304]

I think the simplest solution would be to have a sliding axle. So, have a 3 axle truck, with the middle axle able to move left and right to negotiate the curves. Then all you have to do is position a touch sensor over said axle. Whenever you're in a turn, the axle will slide and touch the sensor, and any touch of the sensor will mean you're in a turn.

[mikezang]

I think the simplest solution would be to have a sliding axle. So, have a 3 axle truck, with the middle axle able to move left and right to negotiate the curves. Then all you have to do is position a touch sensor over said axle. Whenever you're in a turn, the axle will slide and touch the sensor, and any touch of the sensor will mean you're in a turn.

Can you explain for detail? Do you have any figure to illustrate it? I am interested in that.

[AussieJimbo]

You could put a contrasting coloured technic bush in the middle of the sliding axle and detect it's movement with the light sensor.

Eg. a light grey one of these on a black axle.

I think I'd go for the bogie pin axle connected to a rotation sensor.

:classic:

Edited October 12, 2013 by AussieJimbo

[zephyr1934]

I assume you have the RCX on the train rather than controlling the power to the track. If you do have the latter, a break beam light sensor is one of the most robust train detectors I've seen.

If you just want the system to calibrate to a specific location (that happens to be on a curve) you could do what the GBC folks like to do and have a post near the track that trips a touch sensor on the train.

For the curve detection:

...

- Go with your initial idea. Use a brick built bogey with an axle for the bogey pin and attach the rotation sensor to that,

I don't think the RCX rotation sensor is very sensitive. In any event, a much simpler solution would be to rigidly fix the axle in the truck, run it up through the train baseplate (or equivalent) and then stick a technic connector or beam or ??? on that axle. When the truck turns on a curve, the axle will rotate relative to the train baseplate. You can then have that trip a touch sensor.

Another possibility is that you make your own touch sensor. All the touch sensor does is close a circuit. You could make a purpose built home brew switch that closes the circuit when something moves to the correct spot.

[mikezang]

Is there any figure or image for all of your idea?

[mikezang]

Is it possible to put a part on axle of train bogie plate, when bogie plate is rotated, that part is also in rotation?

[zephyr1934]

Is there any figure or image for all of your idea?

Which "you"? Punting that it might be me, which "idea"? Never mind, you'll get both...

Is it possible to put a part on axle of train bogie plate, when bogie plate is rotated, that part is also in rotation?

Sure, , but you'll have to do something other than a bogie plate. The easiest way is to find a brick with a vertical axle hole through it. There are many, but this might be the most common one,

then hold it in to the truck with a pair of technic plates, then cover it all with tiles. Or you could do a more technic construction, e.g., all of the powered trucks (imagine the XL motors pulled off),

As for the homebrew switches, I don't have a photo handy of the switch end, but here's a shot of the completely reversible (but not as robust) RCX connection. Just imagine touching the other end of one of the pairs of wires together, voila, closed circuit just like a touch sensor.

Here are a couple of links to good pages on RCX sensors and much more: Michael Gasperi and Philo's

[mikezang]

Sure, , but you'll have to do something other than a bogie plate. The easiest way is to find a brick with a vertical axle hole through it. There are many, but this might be the most common one,

then hold it in to the truck with a pair of technic plates, then cover it all with tiles.

Thanks a lot, though I used a bush to fix axle, but your idea is better.

Now my own bogie has a rotation sensor to check velocity, a vertical axle to another rotation on the front of locomotive to check if train on curve, then there is a light sensor to check IR from RCX for proximity. On the back of train, there is a train motor and a motorized uncoupled with touch sensor for coupling or un coupling. On the middle of train, there is it a RCX.

This train will run automatic by brickOS program, it will forward in specific velocity even on curve, It will pause if found objects in front of train on straight track until objects removed, it will uncouple car and couple car after sometimes. I will show you when I finish it.

[hoeij]

I want to know if someone know how to check if a locomotive is on a curve track?

One way is to use a axle to instead of bogie pin, then put a rotation sensor around that axle so that curve track can be checked.

Does anyone have any more simple way to check locomotive on curve track?

What about the gyro sensor? It can detect if the loc is turning.