NXT compass sensor

[TheOmeganator]

I don't get it.

[brdavis5]

@TheOmeganator The robot maintains a constant magnetic compass heading, using a compass sensor.

[ninja1dalbem]

is that really a "compass sensor"? I mean, had you use something that isn't in the default kit?

[brdavis5]

Yes, it's really a compass sensor; it is made by a company called "Hitechnic", and sold both by them and through LEGO's own website. It's not something in the stock kit... but it is fully compatible.

[brdavis5]

It's a line... an arbitrary line. You draw it one place, and I draw it at another. Those chips and electronic components you use are no less "premade" than the finished boards and ABS casework I prefer. Both are fun ways to enjoy accomplishing something... and both have strengths and weaknesses.

[skierplaterandy]

i dont like lego robots very much. i prefer arduino, its already pre-built, but if you wannt get advanced you can get the atmega chip and program it yourself.

but still those lego things arent very good. the programming is limited.

[brdavis5]

Well... to each his own. With LEGO, you can see some of the things I can do, and I can do it easily. As to programming... if you want to, program the Mega sitting right on the NXT - plenty of folks have done it. As to "not very good"... well, the example in this video took me about 5 minutes to program, and only 15 to build. How long would it take you to do it with "off the shelf" arduino's & megas?

The programming (NXC, Java, pbLua, etc.) is only as limited as your imagination & abilities.

[skierplaterandy]

i just find it much more satisfying when a project that you built comes togeather.

for example, i just finished the basic build of my POV (persistence of vision display)

if i were to buy something that you just assemble, its not the same as actually building it yourself.

its just preference, you get what im sayin?

plus i dont wanna pay for mindstorms, ther expensive.

[brdavis5]

I completely understand that it's a preference; there are people who don't understand why I bother building a robot that plays chess or something similar, because "you can buy one that does that". It is in the creation that the fun is (for me, & you). For me, part of the creative fun is using the finite pallet of LEGO parts - not inventing my own, but rising to the challenge of the limitations. And yes, they are expensive, no argument there.

[skierplaterandy]

XD

have you ever modded any of your lego stuff to make it do things the default parts cant do?

[brdavis5]

Like what? There's an awful lot the "pure LEGO" can do... like handle a free-fall from 80,000' at temperatures of -70° C and accelerations over 5 G's, with ground impact at 30 kph, and survive just fine (yep, I've done that... and amazingly the stock ABS can handle shock loads at those temperatures). I've certainly used custom sensors, or made my own, etc. And I've beat "sheet metal" robots with pure LEGO ones in sumo, line-following, and maze solving, and have friends who compete in...

[brdavis5]

...roboMagellan using stock LEGO, again against "sheet metal" robots... and again, often beat them.

Will I go outside of LEGO parts? Sure... but you might be surprised how rarely I've needed to.

[skierplaterandy]

sure, but you will get what you pay for. i just completed a project that cost me about 40 bucks in parts, and it would barely be possible with lego parts. and if it was, it may cost into the hundreds.

it uses led lights and a spinning base to create images.

i think that the sheet metal bots you have gone up against probably didn't cost more than 90 bucks to build.

that's why i like to build my own. if i decided to go high quality, then it will cost a little more.

[brdavis5]

Persistence of vision systems using LEGO have been done several times (most recently, in the book "Extreme NXT, Taking your NXT to the next level"... it's the cover photo, in fact). As to the sheet metal bots costing "only" $90... think again. And mine are 100% reusable. Yep, the NXT is expensive... but I can use one set of parts and motors over, and over, and over...

[skierplaterandy]

you shouldnt say my parts arent re-usable. because they are highly reusable. the only disadvantage to building yourself is assembly/disassembly will take longer, and it will be trickier.

i can see why you want to use lego, but i just get more gratification from building something from the ground up.

[brdavis5]

How many times can you resolder a SMD? Vacuum up traces off a protoboard? Reposition the wire leads of a resistor? Don't knock the time factor either - the fact that I can test and discard several designs in the time it takes to do one design using less forgiving hardware is significant.

As to ground up, I completely understand that... but *neither* of us is doing that. I suspect you buy finished parts from DigiKey or something similar, not wind your own motors or spec your own resistors.

[skierplaterandy]

true, but still, its more than using premade parts.

[ForrunnerAlex]

Well you CAN use Java or even C if you have the knowledge to do so with the NXT brain.

[skierplaterandy]

@ForrunnerAlex

Lego Mindstorms NXT Intelligent Brick:

4 input ports, 3 output ports, + bluetooth. price: CAD 214.99

Arduino Duemilanove (development board for atmega 328):

6 analog inputs, 15 digital inputs/outputs, serial communication via usb. price: CAD $31.29

if you want wireless, xbee wifi sheild: $25 + xbee unit: $27.11

totaling 83 dollars.

if bluetooth is absolutely essential they have a $150 bluetooth board aswell, but usb is just fine to me.

and mine is more then just a toy. :)

[Nadrealis]

@skierplaterandy No, it's not. Arduino is for lazy people and/or dumb people. It is in no way a real development environment. Use a BASIC Stamp kit, program something interesting, then get back to me about how the Arduino isn't "just a toy."

Sorry, but to any real hardware engineer or applications engineer, an Arduino is laughable.

[AZNFlipy12]

hey i used the same stuff in CTS

[Elliot5075]

lol he must be angry at you just so he could be lazy

[spectrex1]

The turntable looks suspiciously like the one in my microwave. I'm going to go check brb.

[brdavis5]

I'm certain that turntable isn't the one from your microwave, as I remember taking it out of *my* microwave ;)

[firewurker]

i have a microwave with a turntable but the turntable is bigger :3

[tacksta4]

Alright i just got NXt what does everyone mean by NXT-G language and all that?

[smiletogreet]

too easy and u r 2 funny !

[em01he]

What program did you use?

If RobotC YAY!! If the lego program...why?

[brdavis5]

First, why should the language make a difference? The goal here was to get a certain result... Second, this example is programmed with NXT-G, because it took me about 30 seconds from conception to functioning program. At the time, RobotC hadn't been released... and it still won't run native on my platform, so it isn't the option for everybody.

The fact that you can't tell the difference here probably points out how little it matters...

[hoodie102]

LOL!!! awsome robot is trying to stay on it and not lose the connection to the south LOL

[chadcardwell]

Nice demonstration! clever idea with that turntable too.

[brdavis5]

Thank you - yes, it was a clever idea, but I must admit I saw a similar example (although rougher) at a LEGO event, when a 3rd party sensor builder was demonstrating their version of a compass sensor. So I can't claim complete originality :).

[XBillums]

I just got my Compass Sensor and I have a quick question, is it okay if it rattles when shaken? Does yours rattle? If you could get back to me, that would help a lot, thanks.

[brdavis5]

Try it; if it works, it's OK :). Seriously, some of my sensors do rattle slightly, but still work, so *if* it works, I'm not sure I'd worry about it.

[cl3rkenwell]

I mean south pointing chariot! Lol no robots back then.

[cl3rkenwell]

Didn't the ancient chinese use a south pointing robot?

[Jakobus9000]

why is the sund sensor placed on your robot? is in the south some noise?

[brdavis5]

The sound sensor was used for other programs. This robot (JennToo) is a small platform that I use to test or demonstrate many different programs.

[SolomonRacer]

i feal sorry for the robot :(

[brdavis5]

I'm not sure why - it looked to me as if it was having a fun time :)

[1root]

poor robot :(

[mavamaarten]

cool !!!

[jopio333]

can I download the nxt g program?

[wiinotps3]

cool

[squane34]

I dont have the compass sensor:so I wouldnt know, but if there is no icon for the compass, how do you program the robot to use the compass as a sensor?

[brdavis5]

There are two ways: first, you can have the software look at the sensor as if its an US sensor, and it will retrieve the angle divided by two. Second, there *is* a "compass icon" block. NXT-G allows you to author and add your own blocks, and HiTechnic has a block all ready for download. There is a simple patch that allows you to add such 3rd party blocks at LEGO's Mindstorms site.

[jopio333]

I know. Is there a nxt g program for this. I have the sensor!

[brdavis5]

I never put the program out because it was really simple (in NXT-G): a loop that takes the relative heading, using the sign to control Move direction, and the magnitude (usually scaled up) as the Move power. That's it. I guess I should put it up someplace.

[benjaminventura]

Nice work! I didnt know NXT had a compass

[brdavis5]

The compass isn't made by LEGO, but it's a "Certified by LEGO" product, and you can buy it through them; it does NOT come with the kit (retail or educational), you must purchase it seprately.

[benjaminventura]

i see. Well I didn't know that there are already 3rd party products for NXT either! I need to get one an NXT one of these days.

[carlosdent]

The system will serve to tune a satelite antenna?

[brdavis5]

Huh. Yes, you probably could use this to make a LEGO-driven tuner that would point the antenna to predefined positions. Although I'm fairly certain I wouldn't call that a really *practical* use, it could be a fun one.

[8000000]

hi

were can i buy one from?thank

[brdavis5]

There are currently two companies making compass sensors for the NXT, HiTechnic (www.hitechnic.com) and Mindsensors (www.mindsensors.com). I have both, and the one in the video is from HiTechnic.

[beeant]

is this a compass or the eye sensor trying to find the right one

[brdavis5]

This uses a custom 3rd party sensor supplied by HiTechnic. The "eyes" are the standard LEGO ultrasonic sensor, and while they look good, are not used in this example.

[AAMOSS]

linke: http://www.youtube.com/watch?v­=wbb-iBUa6d8&eurl=

[AAMOSS]

i be happy if you look on me robot and write reaction of man thet have a lot of experience !

[AAMOSS]

really nice man!!!

i like this !

how do you do thet? (command)