May 26, 2006

Another Screen-Capture video

I received an email asking if I could show how the wiring works when connecting blocks...

Well, it's very simple and I hope you're not disappointed - no fireworks or any special animation... you just click on a port/plug and drag to another... if the wire is colored (in this example, yellow) it means you've got a valid connection... a dashed line indicates a broken wire meaning you've incorrectly connected two plugs (for example, an output plug that puts out TEXT connected to a plug that is expecting an Integer).

It's another .EXE file... sorry, but that's how the software saves it... view it here.

11 comments:

Tom Williamson said...

you should give CamStudio a peek. I use to do screen captures and it works great. http://www.camstudio.org/

Philo said...

I noticed those mouse shaped cursors when you click on something... is it related to your mouse driver, or do you have a NXT-G version different than mine???

Jim Kelly said...

Philo,

I think that's a feature of the screen-capture software... it doesn't do that when I'm actually using the software.

Jim

byronczimmer said...

And for those interested in what this program does...

When the program runs there is a 1% chance that the NXT says 'Hello' and a 1% chance that the NXT says 'Goodbye' and a 98% chance it doesn't seem to do anything. :)

If it were wrapped in an infinite loop, it would randomly say 'Hello' or 'Goodbye' every so often.

I assume, based on the mouse-shaped cursors showing a click that to get a wire to 'bend' that you have to click mid-way through the drag?

Very intuitive.

Thank you Jim!

Jim Kelly said...

There was a step that I forgot to include in the small example - I intended to set the lower limit to 1 and the upper limit to 2... that way the Random block would generate ONLY a 1 or 2 - this value would feed into the SWITCH block and "Hello" or "Goodbye" would occur... because I didn't configure the RANDOM block, you are right - 1% chance for Hello, 1% for goodbye... 98 nothing.

m. said...

Very interesting, thx (not NXT ;)) for that video. I never saw NXT in reallity (yet).

I was wondering - when you program one motor, lets say "start turning left with 2rps when i press that button", do you also have to tell him when to stop? In what way do you do that?

I would like to have few options here:
- stop when i un/press button
- stop after 5 rotations / 10 seconds
- stop when the torque is higer than x Ncm

I think the last one should be build in automatically, otherwise i will defenetly break my LEGO ... :(

I hope someone understood me, i am new in this exciting field of robotics!

Have fun :)

Jim Kelly said...

You can specify for motors to spin in 3 ways:

Unlimited - keeps going until another BLOCK (such as a LOOP or Sensor-Check) triggers it to stop.

Rotations - You can specify a number of rotations for the motor to perform before stoppign (this answers one of your questions).

Degrees - specify a number of degrees (positive integers - rounds decimal points down)

Seconds - specify time frame for motor to operate in number of seconds.

You could tie a motor's motion to the touch-sensor in either the pressed or released position. For example, holding down the touch sensor could start the motor spinning - releasing the sensor will also stop the motor.

There is no way that I know of to determine torque and to disable a motor if the torque is too high. You can stop a full-power spinning motor with your hand, so breaking a motor due to high-torque seems unlikely. When a rolling bot hits an obstacle, the motors will stop spinning if the resistance is too high... this happens a lot when I'm testing and so far I haven't damaged any of my motors from burnout.

m. said...

Oh, I see. Apparently I got wrong idea when I was reading somewhere that NXT motors have very high torque, so i thought that it's not stopping if it hits obstacle!

Now i am wondering how powerful motors are. Can they run a heavy car on slope, etc.?

Jim Kelly said...

They do have high torque, but that term is subjective. For a battery powered motor, they are high torque, but I haven't done any real tests on how much weight one motor can push... if I had to guess, I'd say the motors were almost 2:1 ratio... I think a motor could push twice its own weight... but that's a guess and I might be horribly wrong.

Jim Kelly said...

Tom,

I've tried to download CamStudio twice, but no luck - either site is down or it times out on the download... thanks for pointing me to it - I'll try and download again at a later time.

Jim

Brian Davis said...

> Apparently I got wrong idea when I was
> reading somewhere that NXT motors have
> very high torque

They *do* have high torque... for a LEGO motor. Philo has a very nice comparision on his web site, but the short form is that the new NXT motors are about 8 times higher torque than the "old" LEGO gear motors (when stalled). That's a significant increase.

Another factor about how to drive the motors is that you can tell the NXT to try to maintain a consistant speed on the motors, so that if the load is increased (which would normally slow the motors) the NXT can be told to compensate by increasing how hard the motors are driven.

--
Brian Davis

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