As soon as I get the project write up done I will post it to CD as a white paper and y'all can have at the critiques.
Quote:
Originally Posted by Jon Stratis
Oh, and to ensure position/rotation of the wheels, you'll want to have feedback on them. I would suggest a potentiometer - this can tell your code exactly which direction each wheel is pointing, and would be a bit simpler than an encoder.
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We figured if we can't get infinite rotations in then a pot would be the simplest method for checking rotation. We've had experience with them (Logomotion arm and our use of a pot won us Rockwell Innovation in Control award at Greater KC)
Quote:
Originally Posted by Alpha Beta
In 2010 we loved using a mercury slip ring from Mercotac. I believe we had some donated. They were later outlawed that year and we switched to a twisting loop of wire and used software to keep track of how many twists we had undergone. I think recent rules have allowed for them again.
In 2011 1717 steered the opposite corners together, allowing them to create a diamond wheel pattern and spin in place to reorient. That would have been our next iteration had we continued with swerve.
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Two things about this post:
1. Slip rings. We looked into the wikipedia, and we think we understand how they work but if someone could give us a somewhat more simple explanation for us to check against that would be appreciated.
2. How would one go about steering opposite corners without using a motor per corner? We would like to keep things chained together for sake of simplicity, but with the talk of simplicity on the other side of complexity, if one can justify using individual motors but programming them as 2 motors (ie utilizing a pwm y cable) then we'll take that. I imagine that if we do use individual motors but code them as 2 then it might make a transition to full individuality simpler.
Quote:
Originally Posted by Alan Anderson
You can completely avoid the problem of getting electricity to a motor that swerves with the wheel. Using coaxial shafts and bevel gears, you can keep the motors stationary and transmit mechanical power through the rotating parts.
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We've thought about using bevels or miter gears before to transfer power but the calculations and precision necessary aren't exactly something our team are known for.
Yes this sounds somewhat counter intuitive to creating a swerve drive if we can't pull off something extreme, but we think that if we can keep the swerve drive as simple as a swerve drive can get then we might be in the clear.
Quote:
Originally Posted by Aren_Hill
But the resource drain is enormous, and for that reason I do not see us pursuing it in the near future, I'd like to save some time for other parts of the robot so we can put on a little bit better show than this weekend (we were very very far from prepared due to other circumstances).
The technical learning benefits of doing a swerve on the other hand are enormous, from Concept to CAD to Machining to Programming to Driving, you learn an incredible amount due to the complex nature of the system and the level of performance you could potentially extract from it.
For that reason pursuing a prototype in the offseason is fairly okay, just be watchful of the "man this is so cool we should do it in build" as I've embarrassingly fallen victim to it so many times before, with varying results.
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As far as the resources go, our school district is fortunate enough that research projects get a somewhat substantial budget, though it isn't quite a black budget. As long as we can minimize the cost and we're not attempting to buy the moon we're alright.
As far as the technical learning benefits, that is one of the reasons we would like to pursue this. Myself and a few other kids are in a pilot FIRST Robotics Engineering class, and with CowTown over (Our only off season), we're looking for something to do each day for 2 hours until season.
This being said, we are also going to do a project write up for a 6 or 8wd that may be used in season. Should it be necessary I will open another thread with similar purpose to this thread about that drive. Also note that should we only be able to do one project, the 6/8wd project will take precedent over this project and swerve will be shelved as a theoretical project.