Hall Effect Sensor.

[Al Skierkiewicz]

Originally Posted by xxmaddjxx

Arghhh! I don't understand lol.

Ok the Hall Effect sensor counts teeth and has to be mounted very close to the gear.

The accelerometer measures acceleration. How is that done and where does it have to be mounted.

How do all these values come together in the RC and help me?

What does the code that we get for both these sensors do?

If you know what your final gear ratio is (or you test to find out the correlation between counts and inches moved on the floor) you can determine how far the robot has moved. If it runs straight, you can tell where it is at any moment by keeping track of the counts. If you use the accelerometer, you can tell how much the robot has turned (or if it has turned the amount you want it to) so you now have direction and distance. Combine the two and get a rough idea where you are on the field. Be careful, the accelerometer output is proportional to the acceleration in one direction or the opposite direction. If it is mounted parallel to your direction of travel, it has no output. Read the spec sheet carefully to learn all of the nuances of the device and how to best filter out the info you need.

[xxmaddjxx]

Originally Posted by Al Skierkiewicz

If you use the accelerometer, you can tell how much the robot has turned (or if it has turned the amount you want it to) so you now have direction and distance.

How do you use the accelerometer to know how much you turned and in what direction?

What kind of value does it give out?

[Leav]

Has anyone had any luck with mounting the hall effect sensors?

i haven't found anything that fits them.......

also, if you haven't read the manual it states that you must connect pin 4 to pin 3 externally.

-Leav

[jimsmith2354]

Originally Posted by Leav

Has anyone had any luck with mounting the hall effect sensors?

i haven't found anything that fits them.......

also, if you haven't read the manual it states that you must connect pin 4 to pin 3 externally.

-Leav

Mounting of the Hall Effect sensors - We have drilled out the inside of two small connector housings, sanded off the middle ring on the outside, and will use jam nuts to hold them onto brackets placed near either the output gear or a tone wheel.

From another post, connect to controller using a PWM cable - RED to Pin1 - WHT to Pin2 - BLK to Pins 3 & 4

We will wire, test, then epoxy them into these homemade housings.

Mouser PNs 571-14454211 (x2) and 571-16041961 (x4)

Good Luck,
Jim

[MyFeetHurt]

Hey, Stu, it's Christine. I did some calculations.

Wheel radius = 4", Robot speed = 10 ft/sec, gear by sensor has 45 teeth

2 * pi * 4" / revolution

* 1 revolution / 45 teeth

* 1 sec / 120 "

* 1000 mSec / sec

= 4.65 mSec / tooth

In other words, you can't do this by polling the sensors in a 26 mSec cycle, and you probably can't do it in the fast cycle either.

I think the right way to do this is to hook the sensors to a digital counter and poll the counter. I could be wrong. I don't know squat about counters, it's after midnight, and I can't remember how quickly the fast code cycles.

I won't be there this weekend. See you all Monday.

[Joe Ross]

You can get very similar Hall effect sensors from Newark (they are actually just the next version newer, ATS665LSGTN) for $5. So, teams shouldn't limit themselves to just the two in the kit if they want more. There were 762 in stock when I posted this.