Subject:
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Re: Need help combining steering with odometry in NXC
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Newsgroups:
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lugnet.robotics
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Date:
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Wed, 5 Dec 2007 13:41:59 GMT
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Viewed:
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5278 times
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In lugnet.robotics, Joe Strout wrote:
> In lugnet.robotics, Joe Strout wrote:
>
> > This is true even when I instead use
> >
> > OnFwdSyncEx( OUT_AC, 75, turnRatio, RESET_NONE );
> >
> > which I thought explicitly told it not to reset the tacho counts.
>
> Update: upon a couple more hours' testing, I found that the above command
> actually prevents the bot from turning at all. It will only turn if I pass at
> least RESET_BLOCK_COUNT for the last parameter (of course other combinations
> that include resetting the block count, e.g. RESET_ALL, also work).
>
> Whew, that was a couple of hours wasted! Lesson learned, but I still don't seem
> to be getting good tacho counts, and I'm still curious whether there is a
> standard NXC loop for following a line while measuring distance travelled.
Here is a line follower from my book, NXT Power Programming:
#define SLOW_SPEED 25
#define FAST_SPEED 75
#define EYE_PORT S1
#define EYE_VALUE SENSOR_1
int BlackThreshold;
int WhiteThreshold;
inline int min(int v1, int v2) {
return (v1 < v2) ? v1 : v2;
}
inline int max(int v1, int v2) {
return (v1 > v2) ? v1 : v2;
}
task main() {
// set sensor type and mode
SetSensorType(EYE_PORT, SENSOR_TYPE_LIGHT_ACTIVE);
SetSensorMode(EYE_PORT, SENSOR_MODE_RAW);
ResetSensor(EYE_PORT);
int lowest, highest, SV;
lowest = 10000;
highest = -10000;
while (!ButtonPressed(BTNLEFT, false)) {
SV = EYE_VALUE;
lowest = min(lowest, SV);
highest = max(highest, SV);
NumOut(0, LCD_LINE1, SV);
}
BlackThreshold = lowest+200;
WhiteThreshold = highest-200;
NumOut(0, LCD_LINE1, BlackThreshold, true);
NumOut(0, LCD_LINE2, WhiteThreshold);
until(ButtonPressed(BTNCENTER, false));
while (true) {
SV = EYE_VALUE;
if (SV < WhiteThreshold)
OnFwd(OUT_A, FAST_SPEED);
else
OnFwd(OUT_A, SLOW_SPEED);
if (SV > BlackThreshold)
OnFwd(OUT_C, FAST_SPEED);
else
OnFwd(OUT_C, SLOW_SPEED);
}
}
All you need to do to read OUT_A's rotation count is insert a call to
MotorRotationCount(OUT_A) within the while loop at the end. You could reset the
rotation count just prior to the final while loop and break out of the loop when
the OUT_A rotation count exceeds your limit.
John Hansen
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Message is in Reply To:
 | | Re: Need help combining steering with odometry in NXC
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| (...) Update: upon a couple more hours' testing, I found that the above command actually prevents the bot from turning at all. It will only turn if I pass at least RESET_BLOCK_COUNT for the last parameter (of course other combinations that include (...) (17 years ago, 4-Dec-07, to lugnet.robotics)
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