Ok it’s been a whole week since i updated… SORRY.
Basically Week 1 has been all prototyping and building field elements.
I’ll start with the Grabber.
The team decided that we wanted something lightweight and simple. It needed to be able to grab the cone/cube from either the ground or the human station, and also release the cone/cube on the peg/shelf. As I am writing this, we have gone through almost 10 design iterations. But I’ll show our 1st prototype design:
The idea here was to use a cable to open & close the claw. The claw had sticky surface for grip. The grabber team wanted to upgrade this, so they went with a slide mechanism using a rail. Here are some pics:
Basically the bike cable was squished into a hole (1st image) which would connect to a slide. The 2nd image just shows the other side of the rail, where there is a stationary post with the cable coming out. This prototype worked pretty well, however we scrapped it because we were afraid of it breaking too easily in match, and also because rails like that aren’t consistent enough for a grabber like that.
The next prototype involved a new claw design, hex shafts, and chains.
I unfortunately do not have more pictures of this exact prototype, but essentially we had 2 claws that were controlled by a motor (i.e. a drill). We drilled holes for hex bearings in wood, added hex shafts with chain sprockets and the claw, and spun the chains with the drill. Midway through the prototype, however, we realized that the two claws were not going to close and open, but rather shift left and right in the same direction.
So, we moved on to using string and springs.
The images don’t show everything here, sorry. We added string and a spring/bungee cord, where the spring kept the claws closed while the middle shaft handle opened the claws through a string. Here, the concept worked. The only drawback was that it was very hard to make it work.
We tried to upgrade the prototype, but still no luck in making it easier to evenly open/close.
At this point, we were tired of playing with this idea, so the team discussed using pneumatics. The conclusion was that pneumatics wouldn’t fit our scope because there were 2 different game pieces, and it would also require our Electrical Lead to redesign the entire electrical board.
At the end of today’s meeting, the team wanted to try out gears, which looks to be promising. It’s not finished, so I didn’t take any pictures yet. But it’s basically two 50T gears in the middle with one 10T gear on each side, and each claw is attached to the 10T gears via hex shaft. The motor would be either on one of the 50T gears, somewhere below the grabber on the arm, or two motors–one on each 50T gear.
Ok, now the Arm team.
They initially spent a lot of time doing the math and sketching on CAD and trying to understand the best dimensions, so they didn’t get a lot of building the prototype. The team decided to go with a four-bar linkage design.
This is a very rough prototype. It won’t be made out of wood and plastic, trust me. Over the course of the week, the team made changes to the spacing between the bar linkages, the length of the bars, and the angle between the axle holes.
Here is a very basic CAD model of the four-bar linkage. This just shows the
72T sprocket attachment, which we are using from vex.
I plan on CAD-ing the motor attachment and the rest of the chain sprockets throughout this week.
Meanwhile, one of our senior members is prototyping another arm design—a telescoping pole that extends from the back of the robot. He just started today.
The Swerve team.
Waiting on parts to build the frame. Meanwhile we are just using our practice bot from off-season.
Field Elements.
Finished them today!
Video of swerve getting on the platform. (sorry for the background noise)
Misc.
One of our members is making a 3D printed mount for a camera. Will post pictures about that next time.
