Subject:
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Re: How is this?
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Newsgroups:
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lugnet.robotics.nxt
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Date:
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Sat, 23 Jan 2010 23:37:14 GMT
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Viewed:
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19308 times
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In lugnet.robotics.nxt, Edwin Pilobello wrote:
> The program in NXT-G is simple:
>
> Loop forever
> If Touched
> {
> wait for ultrasonic < 9"
> turn MotorA forward unlimited
> }
> else
> {
> turn MotorA off
> }
>
> If touched and distance > 9, MotorA does not move.
> If touched and distance < 9 MotorA turns
> -- If untouched and distance is < 9, MotorA stops
> -- If untouched and distance is > 9. MotorA keeps on turning!
>
> The last condition is what's bugging us. Why does the motor not stop if
> distance is greater than 9"? I have always assumed the switch block would take
> the bottom (negative) logic when untouched. As it is now, the motor keeps
> spinning until the ultrasonic detects < 9". Obviously, after the motor starts
> turning, it ignores the touch sensor.
I can see how this can happen and it depends on the sequence of events. This
sequence will cause this behavior:
touched AND distance < 9 - Motor turns on
touched AND distance > 9 - Motor running, waiting for distance < 9
untouched AND distance > 9 - Motor running, still waiting for distance < 9
This may be a good time to introduce data wires and using the logic block to do
a logical AND.
Gus
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Message has 1 Reply:
 | | Re: How is this?
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| (...) Yes, change the "wait for 9" to be a "check for 9", and the problem should go away... Loop forever if Touched and distance < 9 { turn on motor } else { turn off motor } Kevin (14 years ago, 19-Aug-10, to lugnet.robotics.nxt)
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Message is in Reply To:
| | How is this?
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| One of my students built the chainsaw model from nxtprograms.com. He wanted to make the blade turn only when it was at a distance less than 9 inches from the table. So he attached an ultrasonic and made one mod to the program. The program in NXT-G (...) (14 years ago, 23-Jan-10, to lugnet.robotics.nxt)
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