BaneBot Transmission Encoder

[Daru]

Has anyone had a chance to play with the BaneBot Transmission Encoder?

If I am correct, they seem like they would be a good alternative to the gear tooth sensor? With the Encoder Divider they would give a signal similar to the gear tooth sensor, correct?

Our team has never used such a thing before (at least in the years I've been here...) and we're in a situation where using one would be... well, convinient.

Could anyone offer help in this matter?

Thank you,
Dave
706

[Phalanx]

I have not tried or worked with the Banebot encoder. The specifications for it are on Banebots website. Since it's a quadrature encoder it should follow rules/patterns as discussed ina few threads on here. We have used quadrature encoders from other manufactures oursleves would good success.

I would recommend reading this thread:
http://www.chiefdelphi.com/forums/sh...ad.php?t=48756

I would recommend reading this white paper:
http://www.chiefdelphi.com/media/papers/1490

I would aslo recommend reading over Kevin Watsons code and FAQ's for encoders at:
www.kevin.org/frc
http://www.kevin.org/frc/encoder/

There are also other threads here on the subject as well.

[Gdeaver]

You should read the instructions. Seams that the encoder optical sensors need to be positioned to give true quadrature output. This would need some instrumentation. However, the divider board can assist in the calibration. I believe it also cleans up the raw output (sharpens the square wave). You should probable buy both.

[psh]

We played around with the encoders today, attached to the Banebot RS-540. There were a couple of things we wanted to determine:

1. Was the interrupt rate high enough (without divider) to disrupt the rest of the processor?

2. How big was the delta between motors going forward versus backward? There was some speculation on the team that the motors would only be capable of doing about 80% of the speed backwards.

Our initial tests, using Kevin's excellent code, concluded that it was a piece of cake to get things up and running. The interrupt rate did not appear to be too disruptive. In fact, I was not able to see a huge impact on available "idle" CPU with two motors genrating a bit over 1K interrupts/sec.

Also, we found that the reverse speed of our motors were about 98-99% of the forward speed. We actually saw a greater difference between individual motors than the forward/backward difference of a given motor.

We are by no means done testing, but those are our preliminary findings. We reserve the right to revise them dramatically :-)

>Per

[Daru]

Just wanted to add that we got our shipment of 6 BaneBots encoders and 6 encoder divider cards. We had a soldering party, so we're ready to go with them. We were playing with one using an oscilliscope (sp?) and we got some cool readings. We need to rig something up so we can get them all calibrated tomorrow. I'll let you all know what we find

[murray2077]

We have built two of the encoders and divider cards. We have also have came across two hurdles to getting them working.

1.) How will we get the divider cards powered without supplying batteries?

2.) How will we get the male ports on the divider cards connected to the male ports on our RC?

[DanDon]

To answer your second question, you could splice 2 PWM cables.

[Jared Russell]

Originally Posted by Daru

Just wanted to add that we got our shipment of 6 BaneBots encoders and 6 encoder divider cards. We had a soldering party, so we're ready to go with them. We were playing with one using an oscilliscope (sp?) and we got some cool readings. We need to rig something up so we can get them all calibrated tomorrow. I'll let you all know what we find

I'm trying to imagine what kind of drive would need 6 BaneBots encoders?

[intellec7]

Not necessarily drive, but manipulators.

[Daru]

It is six for our drive ;D

They're all working great... someone really, really destroyed one of them when they were putting it on. The disk was completely destroyed and it didn't read (at all!) So we're going to need to order another... siigh...

We should be getting our AndyMark stuff monday (finally!) so we can put together our drive train Hopefully it will be driving by Tuesday...

As for calibrating the encoders... it's a fairly straight forward thing. Hook each signal to a channel on a oscilliscope and move the encoder until the square waves are offset from eachother correctly, bolt it down and check it again...

We have built two of the encoders and divider cards. We have also have came across two hurdles to getting them working.

1.) How will we get the divider cards powered without supplying batteries?

2.) How will we get the male ports on the divider cards connected to the male ports on our RC?

To power them you need batteries... I don't know how else to supply power to a electrical device? Run 12v from the battery to the encoder divider power slots. This also powers the encoder itself. Hook the encoders to the encoder divider board as marked.

To connect the divider board to the RC, use a PWM cable

Good luck,
Dave
706