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 .. if everybody else is buying all the thingamabobs so they can practice shoving balls into the whatsit. Maybe what you really want is to buy thingys so you can build a practice whojidingle. Being the only whojidingle robot can be a real advantage come alliance picking time ... - ChrisH [more] |
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Another view of the CIM version
Discussion
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09-03-2009 12:49
Nathan Streeter
Re: pic: FRC-34 2009 Swerve Module w/CIM (Front View)
This looks really nice and clean! I'm eager to get a closer look at some crab pods at Nats... I have a couple questions about this design... First, how heavy is this pod, as shown? Second, what motor are you using to rotate the pod? Third, are you combining the rotating of the pods in any way? (i.e. each independently; fronts together, backs together; right side together, left side together, etc.) Congrats on the design, hope you guys can put it to good use!
09-03-2009 14:05
Ed Sparks
Re: pic: FRC-34 2009 Swerve Module w/CIM (Front View)
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Originally Posted by Nathan Streeter
This looks really nice and clean! I'm eager to get a closer look at some crab pods at Nats... I have a couple questions about this design... First, how heavy is this pod, as shown? Second, what motor are you using to rotate the pod? Third, are you combining the rotating of the pods in any way? (i.e. each independently; fronts together, backs together; right side together, left side together, etc.) Congrats on the design, hope you guys can put it to good use!
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Note: I have a pretty sweet Ackerman vi that I'll post soon.
04-05-2009 16:23
BenX02
Re: pic: FRC-34 2009 Swerve Module w/CIM (Front View)
This is an awesome design. I have a question though, I have been designing some of my own crab modules, but a problem I have run into is wiring. How are you going to prevent the wires from getting wrapped around when your modules are turning?
04-05-2009 16:49
Vikesrock
Re: pic: FRC-34 2009 Swerve Module w/CIM (Front View)
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Originally Posted by BenX02
This is an awesome design. I have a question though, I have been designing some of my own crab modules, but a problem I have run into is wiring. How are you going to prevent the wires from getting wrapped around when your modules are turning?
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If I remember right from another picture of this module the silver piece on the left side of the bottom circle of the module is used as a a hardware rotation stop.
EDIT: Found the post here. The piece is indeed a hardware stop limiting the module to 320 degrees of rotation.
04-05-2009 16:56
sgreco
Re: pic: FRC-34 2009 Swerve Module w/CIM (Front View)
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Originally Posted by BenX02
This is an awesome design. I have a question though, I have been designing some of my own crab modules, but a problem I have run into is wiring. How are you going to prevent the wires from getting wrapped around when your modules are turning?
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Many teams don't like coaxial swerve because of bevel gears and things, but coax is one way to avoid spinning wires.
04-05-2009 17:58
tdlrali
Re: pic: FRC-34 2009 Swerve Module w/CIM (Front View)
"anything over 360 of motion is overkill"
not at all, you get a much better response time with full rotation, since worst-case for full rotation is 90deg (you can always find the closest goal within a max of 90deg), whereas the worst-case for non-full rotation is twice that.
also, with non-full-rotation, think of the situation where you're approaching the limit from one side. as you pass through the limit, the module has to turn 180deg (or however far), which makes for really weird driving. this problem doesn't exist with full rotation
for wire wrap, in 07 and 08 (when we did non-coaxial, with cims in the modules), we simply kept track of the number of full rotations, wrote them to the eeprom (persistent across reboots), and had a software limit in the number of rotations. the "unspinning" happened either on button press or automatically during idle time (no joystick inputs).
04-05-2009 18:18
AdamHeard
Re: pic: FRC-34 2009 Swerve Module w/CIM (Front View)
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Originally Posted by tdlrali
"anything over 360 of motion is overkill"
not at all, you get a much better response time with full rotation, since worst-case for full rotation is 90deg (you can always find the closest goal within a max of 90deg), whereas the worst-case for non-full rotation is twice that. also, with non-full-rotation, think of the situation where you're approaching the limit from one side. as you pass through the limit, the module has to turn 180deg (or however far), which makes for really weird driving. this problem doesn't exist with full rotation for wire wrap, in 07 and 08 (when we did non-coaxial, with cims in the modules), we simply kept track of the number of full rotations, wrote them to the eeprom (persistent across reboots), and had a software limit in the number of rotations. the "unspinning" happened either on button press or automatically during idle time (no joystick inputs). |
04-05-2009 18:21
Aren_Hill
Re: pic: FRC-34 2009 Swerve Module w/CIM (Front View)
The whole reason I went coaxial was so the programmers couldn't break the drivetrain by spinning too far lol
with coaxial they can send whatever commands they want at it and all that would happen would be a bunch of random spinning at worst
04-05-2009 18:28
AdamHeard
Re: pic: FRC-34 2009 Swerve Module w/CIM (Front View)
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Originally Posted by Aren_Hill
The whole reason I went coaxial was so the programmers couldn't break the drivetrain by spinning too far lol
with coaxial they can send whatever commands they want at it and all that would happen would be a bunch of random spinning at worst |
05-05-2009 07:13
sgreco
Re: pic: FRC-34 2009 Swerve Module w/CIM (Front View)
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Originally Posted by AdamHeard
yup, can't trust those programmers
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But then again, without code, the robot is just a door stop...
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