Team 1658 flying inverse differential swerve Video+CAD files
 

As previously seen here: http://www.chiefdelphi.com/forums/sh...d.php?t=140181

Here is a video of a quick test run we did. We don't have full functionality yet but serves well for initial demonstration purposes of this system.

https://www.youtube.com/watch?v=WfxK...ature=youtu.be

Here are CAD(autodesk inventor) files of the system. I'm fairly confident all the parts and dimensions are accurate but as a disclaimer: Accuracy is not guaranteed.

https://drive.google.com/file/d/0B4f...ew?usp=sharing

Re: Team 1658 flying inverse differential swerve Video+CAD files
 

I still love this idea. The well-controlled slow driving would have been helpful in 2015 to not knock over stacks when placing your stack. With some pretty basic (or not so basic if you choose) programming, you could make an 'auto-shifter' from differential mode at low joystick input values for better control to normal mode at higher joystick values for faster driving. One less thing to for the driver to worry about. I look forward to hearing more about this project!

BTW anyway we can get the CAD either in STEP format or on GrabCAD so Solidworks users can take a look?

Re: Team 1658 flying inverse differential swerve Video+CAD files
 

On the higher values differential mode is kind of like normal mode since the motors are driving in the same direction, just not same speed. But at full tilt they are the same so our high end is more or less identical.

As far as the CAD goes, I don't have inventor on my home pc so I wouldn't be able to do any conversion until after the season starts but pretty much all the CAD software packages have the ability to convert files from other formats so i'm sure you'll find a way to import the files into your cad package or at worst use an online converter.

Re: Team 1658 flying inverse differential swerve Video+CAD files
 

Interesting, on the video it looked like it went faster in normal mode. Maybe the driver just wasn't pushing the stick as far on differential mode.

Re: Team 1658 flying inverse differential swerve Video+CAD files
 

Ye it was the first time that driver picked up the controls. It can go both faster and slower in a more controller manor but he wasn't familiar enough with it yet to properly show what it's capable of doing. I had a bit more practice with it and could have showed off the various aspects a bit better for comparison but I had to do the recording so can't do both xD we attempted to have someone else record while I drove prior to this but i'm pretty sure that video would make a lot of people puke.... so I ended up having to take the video myself. Certainly not a shining achievement from what can be seen in this video but I kind of like that too so others don't get a full proper demonstration and while it can be seen working the finer details are left to their own imaginations =p Until competition that is then this system will shine in all it's glory xD (if we end up deciding to use it anyway) or they can attempt making one themselves to find out.

Re: Team 1658 flying inverse differential swerve Video+CAD files
 

Can you guys tested pushing stuff with it yet?

Re: Team 1658 flying inverse differential swerve Video+CAD files
 

Why are motors making so much noise even when it's not moving? Feels like a car on neutral :yikes:

Re: Team 1658 flying inverse differential swerve Video+CAD files
 

We did some small tests but no video of it. Nothing is properly setup(the robot is 80 lbs short so traction is very low, we're using clamps to hold some parts on, the chain doesn't have proper guides/tensioners, need more time to refine and implement more code, etc...) so there would be little point in even attempting it. This prototype was a proof of concept and it succeeded at that task for our needs. Real testing will be after we see what the game is to see if we want to continue on this route at which point we will attempt a competition rated prototype.

Re: Team 1658 flying inverse differential swerve Video+CAD files
 

when it's not moving it doesn't make any noise. However when we go at low speeds in Differential mode then indeed it is a noisy machine. That's because the top motors are going full speed and the bottom motors are going nearly full speed the opposite direction. So there are a few parts spinning at very high speeds. That's kind of the whole point of the differential system, we can have high power at very low speeds.

Re: Team 1658 flying inverse differential swerve Video+CAD files
 

Have you thought about trying to optimize this so that the CIM is running at the RPM at which it has the highest power? Or does running them like you describe automatically result in that?

Re: Team 1658 flying inverse differential swerve Video+CAD files
 

it all depends how you want to run the cims. There are various modes of operation which is one of the nice things about the design. We can certainly chose what reference speed the cims run at for varied effects such as most efficiency, or most available power(all out) or anything in between. We will certainly be playing with various methods but as far as which ones we end up using,who knows.

Re: Team 1658 flying inverse differential swerve Video+CAD files
 

Is it a correct statement that it is impossible to stall the top motor? If so it seems like it'd be a good candidate for a lighter and more efficient open-air motor (new 775, e.g.) so long it's geared correctly.

Re: Team 1658 flying inverse differential swerve Video+CAD files
 

If the top motors are going "full speed" (which I read as free speed, or nearly so), they are generating no torque and thus producing no mechanical power. The bottom motors are going "nearly full speed", they are generating low torque, and are operating well down on the power curve. Where does this "high power" originate?

Re: Team 1658 flying inverse differential swerve Video+CAD files
 

I just want to double check, the transmission you are using is similar to this, correct?

Re: Team 1658 flying inverse differential swerve Video+CAD files
 

you can still stall out the motors and while it would work to a degree the total capable speed and power is still reliant on both of the motors so if you used a 775 you will lose in both regards compared to a cim.