pic: 3946 off-season strafe module, oblique view

[chapman1]

Thanks for sharing your prototype! Can't wait to see how it works - because that, after all, is the purpose of a prototype - not to be fully engineered and competition-ready.

[GeeTwo]

I finally have an update worth reporting on this one!

I had hoped to use this as a hook to teach the controls and programming first and second years about pneumatics, which we did not use in 2015. The program and wiring teams did not get on board with this project before build season was upon us. Early during build 2016, the cylinder was removed, the hinged wheel tied off, and a very crudely built control board was added to this so it could serve as the programmers' testbed. I figured the strafe project was history.

Then, in the aftermath of Red Stick Rumble (our only post-season event of the 2016 season), it was time to disassemble or re-purpose the Stronghold practice and test bed robots (the competition robot is being retained as a demo robot at least until build season). Christian, our HP* and bumper guy this year who also did a bunch of controls work, saw the motor, gearbox and wheel on the hinged arm, and asked (probably rhetorically, possibly sarcastically) what this strange mess was for - in my hearing. I ignored the tone, but walked over and explained the plan. He looked at me, and the robot, and at me, and the robot, and said "That would be so cool!" (or something very much like that).

In about four hours of build spanning two sessions, the removed pieces were located (or purchased) and replaced, the control board was centered, a hole was drilled in the control board for the cylinder to hang through, and the battery was tied down (not competition ready, but enough for a test drive). The roboRIO was still loaded with the Stronghold code, but they wired it so that the arm raise-lower became the strafe raise-lower and that the ball intake roller became the strafe motor. (This bothers me as I write this, because I realize that it means we had a CIM controlled by a spike.)

I would like to say that it worked the first try, but that would be a slight exaggeration. The robot was quite light, and the pneumatic working pressure was a bit too high, and the two wheels not pictured here came right of the floor and the frame stuck up about sixty degrees above horizontal like some over-the-top low-rider trick. Once the air pressure was dialed down, it worked almost exactly as designed. I did not note what pressure was needed, but Christian obviously did, because they did the trick and driving several times that evening always according to intentions.

I shot some cell phone video, but it's too long to e-mail to myself. If I can get it off the phone onto the network, I'll post a youtube link.

The strafe wheel made a significant racket as it slipped (should have been on a motor controller rather than a spike), and we new have skid marks on the shop floor, but we did achieve my primary goal for this project: To move H-drive from the "we failed to make this work in 2015" column to the "we successfully prototyped this drive in 2016" column.

To Corsetto: We didn't fail fast, but we did finally learn from this one outside of build season! I don't think that anyone came away with the thought that this was good enough for competition, but we spent less than $100 (excluding about 60 man-hours of our time over many months) on this and learned a bit of the art of the possible. That is time and money very well spent, in my book.

*For those of you at Bayou and/or Red Stick, Christian is the drive team member who wore our green 'fro wig this year, and who led our cheers from the stands with the gonfalon (standard).

[GeeTwo]

The video.