Oh man, day 6 already? I hope everyone is having a good week of prototyping. Here’s a lightbulb pear to brighten up your day.
The Ghost of Meetings Past
On Tuesday we began our prototyping efforts in earnest, and we’ve already learned a lot. We’ve tried mechanical alignment, cone grabbing, corb intaking, and corb shooting (“corbs’’ are cube+orbs - name credit to @dydx ). We developed and tested an over-bumper intake for corbs. They worked well with compliant wheels, but we still need to test a way to vector the corbs inwards. Using the Thrifty Bot Mecanum wheels didn’t work, but the larger 4-inch Mecanums seemed to perform better, so we’ll have to do a bit more testing.
We also prototyped a corb shooter; the accuracy is questionable at best (except for in this video apparently), but the results are promising, and we should have more details coming in our Sunday post.
Tuesday also marked the day that our rookie coders used one of the 2022 EveryBots we built to start trying to make the robot automatically move when at an angle measured by an ADIS16470 IMU and balance itself at the charging station. We started off with a simple P loop but modified it a good bit with some exponentials. We did find that over the time of testing, we definitely needed the capability to reset the gyroscope so we added a reset button.
As for our reacher team, they are still theory-crafting the best solutions to how to extend and get to the L3, working on potential arm/elevator designs. As they worked through a risk-reward discussion, they came up with some reasonable goals for how many points our robot should score by our first competition.
Wednesday was our big mail day. We got our order for a lot more cones for the field, some REV Ion stuff, and our Thrifty Bot elevator.
Our reacher team worked on assembling the TTB elevator. They mostly finished the base stage, as well as started the second stage. The project will be done by Friday this week, so keep your eyes peeled for that.
Our rookie programmers also continued to develop Charge Station auto-balance. Since we were seeing erratic behavior while using linear power control, we tried to find a non-linear formula that would restrict excessive power for larger angles. We chose the formula 1/5 * ^⅓, where x is the degree offset. We also ensured we’d have a minimum power applied since the robot won’t even move without some minimum (around 20%). Even after using this formula, we still had a lot of over-correcting causing erratic behavior. So we studied PID and implemented power-based PID control. We had minimal time to tune, so we reverted back to our formula for the demo and video. However, we also know that our bridge right now isn’t representative of the real field. We believe the double hinge design and the weight of the real bridge means it will “want” to be balanced. Our current build is light enough that it becomes out of balance very easily
As our designs become more and more definite, we find ourselves moving away from a mechanical alignment system. Due to a variety of reasons, we don’t believe a system like this will work for us, primarily because we found that having a slot in our robot where the hybrid zone dividers could fit into would often bind up and get stuck, while also failing to center our bot the way we intended.
Thanks to our wonderful parent and alumni volunteers, we now have a full-sized charge station, as well as two-thirds of a grid. However, we have a few issues with the charge station; it is about 60 pounds lighter than expected, is a major pinching hazard, and also doesn’t sit level most of the time. We’ve had more injuries and close calls than the 2020 and the 2022 truss combined and we’ve only had it for 2 meetings. We don’t expect the wooden version that FIRST provides plans for to be representative of the actual field charge station.
The Ghost of Meetings Yet to Come
Going into Friday and the weekend, we’re going to begin looking at better defining our robot architecture, and we’ll also host our first design review. We’re almost ready to assemble all of our swerve drives for our practice and competition robot. We’re going to keep prototyping our designs for this year and begin CADing and CNC’ing more sophisticated prototype designs.
When people ask me how to make a schedule, I like to answer that, by the time you begin, “you are already behind schedule and over budget.” For once though, I don’t think that’s true (knock on wood); we’re doing a really good job working on parallel prototypes and designs, and I feel that if the team gives a focused effort next week, we can have a robot working by our week 2 deadline.
hopefully this will get more commitment from team members than prior attempts at various blogs.
