Subject:
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Re: Problems with NQC and math operations
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Newsgroups:
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lugnet.robotics.rcx.nqc
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Date:
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Sun, 2 Feb 2003 19:45:26 GMT
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Viewed:
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5274 times
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Jeff,
Your problem is with the 16 bit integer size that NQC uses. All integers
are in the range -32768 to 32767. Using 10000 to simulate fixed point math
operations is killing you. Everything works when you replace theta and D
with constants because the compiler evaluates the equation and replaces it
with a constant.
Dean
>
> D = abs(Rotation);
> theta = Direction * 18/5; //since the compass sensor uses 0-100 I
> have to convert to the standard 0-360
> oldx = currentx;
> oldy = currenty;
> if (theta >= 0 && theta <= 90) //this is only the portion of the
> code if the robot is moving in the direction of the first quadrant
> {
> theta = 90 - theta;
> currentx = (10000 * 3 * theta / 180 * D) / 10000;
> currenty = (10000 * D - theta * theta * 125 * D/ 81)/10000;
> //(1 - (10 * (theta * theta))/64800) * D;
> }
>
> So if I simply replace theta with 51 and D with 15 the robot returns the
> correct value of
> 12 for current x and 8 for current y.
>
> But when I use the variables...either point the robot in the right direction
> and right number of rotations, or even initialize them at 51 and 15...the
> robot returns 0 for currentx and currenty...
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Message has 1 Reply:
 | | Re: Problems with NQC and math operations
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| Dean, Well, that was the problem...changing the 10000 to 100 makes me get a value back, however I think the error is too big for the robots to navigate effectively..I'll probably have to learn legOS so I can use floating-point and get more precise (...) (21 years ago, 2-Feb-03, to lugnet.robotics.rcx.nqc)
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Message is in Reply To:
| | Problems with NQC and math operations
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| Hi- I'm currently working on a project to get a dead-reckoning navigation system to work with NQC and the RCX. Right now I have a compass sensor and a rotation sensor hooked up and the idea is that with an angle and a distance, I can get an x and y (...) (21 years ago, 2-Feb-03, to lugnet.robotics.rcx.nqc)
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