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  #16   Spotlight this post!  
Unread 09-02-2017, 15:25
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Re: 2017 Bosch Seat Motor

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Originally Posted by chesterm View Post
We have noticed the loss of counts also. In our case it appears to do well when speed is at 50% or less. Going above that led to increasing loss of counts. We are planning on a home switch to re-zero counts every time our tilt returns to the up position. Haven't tested it yet, but I expect it to work out ok.
I wonder if the frequency of checking might be the problem. 20 RPM free speed is 1/3 rev/s with 175 pulses per rev = ~60 pulses per second. If your frequency of checking is any less than that you'll probably miss counts. Not sure how your program is checking but if you have other calculations happening at the same time it might be part of the problem. Keep in mind I don't have much knowledge of FRC code. Best solution in that case is just the mentioned zero each cycle or count separately on an Arduino or the like.
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Unread 09-02-2017, 15:38
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Re: 2017 Bosch Seat Motor

I opened up one of these yesterday and found something that's pretty different than the cut-away on the WPI site. That one had a plastic gear broached in a star pattern, the one we have seems to be a plastic gear driving (by some kind of rubber damper) a metal plate with an output that looks more like a plus sign. Needless to say this is far harder to machine an output shaft for than the hex or square recommendations in the resources.

We considered taking the whole back plate off and bolting the mechanism directly to the rotating plate but I'm concerned about compromising stability and the potential legality issues. Another thought was to tap the weird pointed output on the exterior of the motor and use red locktite to connect a drive screw to it...though this is suboptimal...

Anyone have any ideas of (preferably machining-free) ways to adapt this motor's output?

Thanks.
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Unread 09-02-2017, 15:40
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Re: 2017 Bosch Seat Motor

Please see attached for suggestions...

http://wpilib.screenstepslive.com/s/...sch-seat-motor
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Unread 09-02-2017, 15:43
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Re: 2017 Bosch Seat Motor

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Originally Posted by kprzewodek View Post
Please see attached for suggestions...

http://wpilib.screenstepslive.com/s/...sch-seat-motor
Yes...that's the site I was referencing on my post. On the bottom of the page you can see that the plastic gear is broached in a star (the "two squares offset at 45 degrees") output. Our motor isn't like that: the output is a plus sign, not a star.
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Unread 09-02-2017, 15:44
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Re: 2017 Bosch Seat Motor

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Originally Posted by Nato View Post
Yes...that's the site I was referencing on my post. On the bottom of the page you can see that the plastic gear is broached in a star (the "two squares offset at 45 degrees") output. Our motor isn't like that: the output is a plus sign, not a star.
Can you send a picture? This came in the KOP?
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Unread 09-02-2017, 15:46
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Re: 2017 Bosch Seat Motor

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Originally Posted by kprzewodek View Post
Can you send a picture? This came in the KOP?
I'm pretty sure it's from the 2017 KOP. There's a chance I'm getting it confused with something from last year or maybe something else, but I don't think so.

I can get a picture on Friday and I'll attach it here.
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Unread 09-02-2017, 15:56
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Re: 2017 Bosch Seat Motor

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Originally Posted by Nato View Post

I can get a picture on Friday and I'll attach it here.
That will help. You have me stumped. We do have something close to what you describe but unlikely to have been mixed up.

Last edited by kprzewodek : 09-02-2017 at 16:53.
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Unread 09-02-2017, 17:05
Nick Donahue 40 Nick Donahue 40 is offline
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Re: 2017 Bosch Seat Motor

Hi, I am from team 4028 (The Beak Squad) and we are choosing to use the Bosch Seat Motor this year. We typically use Talon SRX motor controllers to control all of our motors, and from what I have seen we can control this motor with them. My problem is I am unsure if we can use the hall encoders with the Talons, meaning, can we plug the encoders some way into the Talons instead of the Analog In port on the RoboRio? In theory this shouldn't work because the Talon SRX accepts a Digital Encoder import, but I can't find a reason why the encoder from the Bosch motor would be analog. Does someone know if the encoder is digital or analog? Has anyone tried patching it into a Talon SRX???
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Unread 09-02-2017, 20:42
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Re: 2017 Bosch Seat Motor

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Originally Posted by Nick Donahue 40 View Post
I can't find a reason why the encoder from the Bosch motor would be analog

Did you look at the datasheet, available via a link on the AndyMark page for this product?


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Unread Yesterday, 08:44
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Re: 2017 Bosch Seat Motor

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Originally Posted by Nick Donahue 40 View Post
Does someone know if the encoder is digital or analog? Has anyone tried patching it into a Talon SRX???
It is analog
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Unread Yesterday, 12:37
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Re: 2017 Bosch Seat Motor

Hi,
I understand from this thread that some of you have already managed to get the correct encoder data (despite losing some ticks).
Can anyone explain how it can be done?
Our initial try was to count the voltage peaks using analog trigger, analog to digital and then a counter.
In all the examples, we saw that the limits of the analog trigger are set between 3.5-5 volt.
However, our voltage measurements show values between 0.13-0.14 and they are not consistent (can move to 0.12-1.13).
Can anyone point to what we may be doing wrong?
Thanks.
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Unread Yesterday, 13:33
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Re: 2017 Bosch Seat Motor

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Originally Posted by Rami Marelly View Post
Can anyone point to what we may be doing wrong?
Thanks.
Have you checked with an oscilloscope to confirm you're getting a signal. Also, make sure you follow the wiring diagram and that you have a resistor in the circuit close to 200 ohms.
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Unread Yesterday, 14:15
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Re: 2017 Bosch Seat Motor

Quote:
Originally Posted by Rami Marelly View Post
Hi,
I understand from this thread that some of you have already managed to get the correct encoder data (despite losing some ticks).
Can anyone explain how it can be done?
Our initial try was to count the voltage peaks using analog trigger, analog to digital and then a counter.
In all the examples, we saw that the limits of the analog trigger are set between 3.5-5 volt.
However, our voltage measurements show values between 0.13-0.14 and they are not consistent (can move to 0.12-1.13).
Can anyone point to what we may be doing wrong?
Thanks.
What are you measuring the voltage with? If it's a multimeter or voltmeter, that is too slow to puck up encoder spikes. You will need an oscilloscope to see encoder pulses.
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  #29   Spotlight this post!  
Unread Yesterday, 14:28
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Re: 2017 Bosch Seat Motor

Definitely a mulitmeter is not the way to check since the pulse is read from the armature and there are 175 pulses for each output rotation. The attached picture is a bench reading from an oscilloscope and shows what you should expect from the hall signal. These chips are pretty sensitive to static electricity so be careful. BTW, my power supply only goes down to 6V but it should be close. Each pulse is around 14ms at 12V free speed.
Attached Thumbnails
Click image for larger version

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Last edited by kprzewodek : Yesterday at 14:46.
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Unread Yesterday, 15:44
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Re: 2017 Bosch Seat Motor

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Originally Posted by kprzewodek View Post
It is analog
source please?


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