Effeciency of Gear Tooth Sensor

[magical hands]

I have gear tooth sensors installed. so to test what i did is took a sprocket and placed it on a drill bill and i started spinning hte drill. than i took the gear tooth sensor and placed it near the moving sprocket but i found out that its not very effecient. Like it took so long to count and it has to be so close that it was hard for my hands to hold that close and often it sprocket teeths would touch the magnet.

For optimum results, anyone has any tricks or ideas that they want to share for accurate gear counts? By the way i was using the Kevin's encoder code with a bit of modification.

[seanl]

the magnet and the gts have to so close i think like 1-2 mm

[Nathan]

Yes, I believe when testing ours we put it 1mm away from the teeth and it counted accurately. As a side note though, we could not get our gear tooth sensor to report any kind of directional information, which is why we decided to use a yaw rate sensor for drive correction.

-Nathan

[DarthXar]

Gear tooth sensors can be within .5 and 2.5 mm, but you really don't get a good signal outside of 1 mm. Also, they can't be mounted perpendicular to the gear, but must be in line with them.

We mounted them wrong at first ;3

[heydowns]

We've always had much better luck with optical encoders than GTSs.

The GTS needs a significant amount of ferrous material, and it needs to be extremely close (as previously posted).

Our rookie year, we made optical encoder sensors and discs. The discs were evenly punched aluminum mounted on our wheel axel. The sensors were like those inside a computer mouse (the ball mice, not the new optical style).

Last year we used similar sensors for our shooter wheels to monitor/adjust speed. Here, instead of a punched disc, we made L-shaped, velcro mounted "trip tabs" from lexan.
This was after we failed to find enough mass around the shaft to trip a GTS.

The other nice thing about the optical sensors is that they are very cheap in comparison to pre-fab GTSs.

[The Lucas]

My team tried to use GTS last year on our aiming devices and it was a tremendous failure. After LABview testing the kit GTS, we purchased better (more expensive) GTS. Still it was just too difficult to mount the GTS with the tremendous precision they require and keep them steady (right next to our high vibration shooter).

I think GTS just are not rugged enough to be reliable on a FIRST Robot with all the vibration and impacts. We use USDigital optical encoders for drive and other things. I recommend the S16 series with the Ball Bearing option. We usually just pin a plastic gear to them and connect it to a spur gear in our drive train. The B option greatly increases the max rpm and life of the encoder so you can use it for multiple years.