More data on the Compass Sensor...
Well, I'm away for a day-and-a-half and I return to find weapon systems for NXT! My how this product matures quickly!
After playing around with the compass some more, I realized I wanted a little more detail on how the motors interact (conflict) with the new Compass Sensor. So I did some quick tests:
1. I built a small frame to hold the sensor away from the Brick and one motor.
2. I got the Compass Sensor to return a fixed value of 0 (North).
3. I then slowly moved the motor towards the sensor and watched the value.
In this figure, the compass still returns a value of 0. The Brick shows 358, but it would change a few times and settle to 0.
In this figure, the motor is slightly closer and the value stayed consistently at 2. Not bad. But at other times, the reading would jump to near 280 and then back to 2. An accurate reading, then an inaccurate one. Maybe some pulses from the motor or compass or both?
In this final image, I held the motor next to the sensor. The value fluctuated between 190 and 220 - a 140 degree difference!! So the lesson is this: Keep that Compass Sensor AWAY from your motors.
I imagine that plugging in more motors and sensors may cause even more trouble. I'll play with the sensor some more and let you know what I find.
After playing around with the compass some more, I realized I wanted a little more detail on how the motors interact (conflict) with the new Compass Sensor. So I did some quick tests:
1. I built a small frame to hold the sensor away from the Brick and one motor.2. I got the Compass Sensor to return a fixed value of 0 (North).
3. I then slowly moved the motor towards the sensor and watched the value.
In this figure, the compass still returns a value of 0. The Brick shows 358, but it would change a few times and settle to 0.
In this figure, the motor is slightly closer and the value stayed consistently at 2. Not bad. But at other times, the reading would jump to near 280 and then back to 2. An accurate reading, then an inaccurate one. Maybe some pulses from the motor or compass or both?
In this final image, I held the motor next to the sensor. The value fluctuated between 190 and 220 - a 140 degree difference!! So the lesson is this: Keep that Compass Sensor AWAY from your motors.I imagine that plugging in more motors and sensors may cause even more trouble. I'll play with the sensor some more and let you know what I find.
Comments
The compass sensor is not allowed in FLL (just like all third party sensors).
Jim,
Interesting discovery. That's good to know, because someone could easily confuse it with a broken sensor.
-Jonathan
But the HiTechnic sensors will be sold officialy via Lego Shop @ Home.
Wouldn't this be almost the same as a Lego product? But then, there are the restrictions on how many and wich sensors you can use, so you're probably right.
1. The FLL has already released its "allowed parts" list
2. Even if FLL considers the HiTechnic Compass 'official', the RCX doesn't an official compass sensor, right?
Jim
Practically, I suspect that as long as the RCX is allowed, there will be no added sensors to the list. And even after FLL (someday?) switches to just the NXT, cost may be an issue. You want to make sure that all the teams have roughly equal resources, which either means adding a compass (or other) sensor to *everybodies* kit, or not permitting them. Just my guess.
--
Brian Davis
-Jonathan
Brian had all the exciting news from BrickFest, how was I suppossed to compete with that?
:-)
Enjoy your weekend everyone - I am have lots to do on my writing project.
- Tony
Is it my imagination, or does the ultrasound sensor perform better the farther away it is from the motors?
This sounds preposterous, I guess. All I know is that when I attach the sensor "high and out" (i.e, far away from the motors), it's much more accurate in detecting the distance to solid objects. (I assume that this phenomenon has nothing to do with electrical interference, but I'm at a loss to explain it).
Anyone else have this experience?
Christopher
MDP - MCP
Jim