Here are some images of the HOTBOT from Week 1 - Waterford
More can be found here: https://goo.gl/photos/4cJchbxw62FGZJ2z8
This is an amazing robot, as always. Every year, the robot design I’m most excited to see is 67’s.
It’s great to see some familiar faces still involved with HOT and FiM, with Jim Meyer as drive coach, Dave Verbrugge as MC, and Tom Nader as game announcer. At the same time, it’s cool to see that the team can have so much turnover in students and mentorship and still put out a fantastic bot.
As a side note, I hope Adam Freeman is having a great time down in Texas, away from the team he helped win 3 World Championships!
I didn’t get to see that many matches from Waterford, but I did note that you were able to score 3 high goals and capture the tower in Quals 33. Then in Finals Match 2 I noticed you guys weren’t scoring high anymore. Was the shooter broken, or did strategy and analysis dictate that low goals were better for you?
Great robot! HOT’s performance this season is clearly at the very high standard that 67 has set for itself during many previous seasons, and the statistical results speak for themselves.
One question: in this picture, it appears that G18 is violated; see example A in Fig. 3-2, in the blue box under G18 in the Manual. Is this typical the climb method 67 used at Waterford? Was the potential G18 violation observed/mentioned by referees, or during robot inspection?
Looks like they are still with in the 15 inches though it may be close. Problem with G18 is that is almost impossible to enforce unless its quite obvious that the 15 inches has been exceeded.
No the shooter wasn’t broken. It was just a strategy change. Our cycle time was much quicker if we just went for the low goal (grab a ball, over defense, score, repeat). Our goal was to defeat the tower in each match. We didn’t need to waste time shooting high to do that.
We had that mentioned to us by another team. We never had a reff say anything to us. However, we did modify our hang code to ensure that the robot remains parallel to the floor as it hangs now.
My recollection from ref certification training (which I completed this year) is that refs are to use their best judgement based on what they can see without entering the field. You can see the ref in the picture, doing just that. Keeping in mind that the configuration I linked only existed for a second or less, and that the final configuration is clearly a legal scale, I think that ref made the right call. No G18.
However, I would expect refs to get better at seeing momentary configurations as the season progresses, so HOT’s programmers are smart to have already implemented a fix that eliminates the issue.
In Finals Match 2 the intake roller was broken, hence the stuck ball.
The cycle time was faster and more reliable scoring low since we did not have a functional camera aim, didn’t want to get in the way of 33, and were having some issues with shooter consistency. Our shooter has been redesigned for Howell.
How has it been redesigned?
Previously we had a 775 pro inside a 4" polycarb drum that drove it through a 2.5:1 reduction with brass gears. This was partially driven by initial packaging concerns, but also because of the ‘cool factor’. Turned out we really didn’t need the motor to live inside there for packaging. This design proved not to be as consistent as we would have liked, but we really didn’t discover that failure mode early enough to change it for Waterford. We got a large variation in top speed - not sure if this was due to gear wear, bearing differences, or inconsistencies between the various motors (we built 3 of these shooters and used a different bearing setup on one of them).
No comment on the new shooter yet - I’ll wait until it works before I say anything.
Mike / Ryan,
I assume there will be no tech notes posted (since I’m not there to make one 
), but can you walk through the specifics of the design?
There looks to be a bike cable in there somewhere, not sure what crazy idea that is used for…
I really haven’t talked to Jim in-depth about the design, so I’d love to know more about it and how you guys came up with it.
-Adam
Looks like 67 might be using a disc brake to hold pivot location for the arm?
We have two disc brakes on our 2016 robot, one to hold pivot location and one to hold elevator location. Both are critical for accurate shooting, as well as holding our hang position at the end of the match.
When you get the hang of it (no pun intended), they’re pretty simple to integrate into a custom gearbox solution.
-Mike
The HOTBOT is looking great again this year! I’m disappointed I won’t be seeing you at any districts this season, but hopefully we’ll cross paths in Grand Rapids!
Sure. The bike cable is used to actuate two bike disc brakes. We needed a way to ensure the robot would hang with the base parallel to the floor. We had several ideas, but then one of the mentors said “hey what about a disc brake”. The brakes are mounted to the output shafts of the arm gear boxes. They are actuated by a pneumatic cylinder.
Mike already explained the shooter. It was really “cool”, but as he said we had consistency issues with speed. We worked on improving gear mesh, wear, etc but no luck. So once we reveal the new design we can talk about it more.
Ball intake uses one 2 inch roller to bring the ball into the robot. We then have two conveyors that direct the ball towards center. One being powered, and the other driven by a cross over loop.
Other then that its just the usual HOTBOT chasis modified to fit the design for the game. We do use pneumatic wheels to aid in crossing defenses. We discussed tank treads, but after some research from past seasons we decided pneumatic wheels were better. They also were easier to package. We also use pneumatic shifting. So I guess we are starting to accept pneumatics into the design, when we never used to use them.
Full disclosure: Mike, Eric, and Jim were the leads this year on design. I was not able to commit as much time as I would have liked this season. I did help bounce ideas around, and aid in design and build where I could. Mike and Jim could go way more into detail.
Thanks! Hope to see you at States Megan!
They work very well. We have incorporated bike brake cable into our designs before, but I believe this is the first time we have used a disc brake. Actuation is fairly easy, and they can support a large load.
Drive train is 2 CIM ball shifters 8wd with 8" AM pneumatic wheels, running 25 chain this year. Pneumatic system was added the Sunday before ship after concerns about our door lock actuator motor shifting robustness. We weighed about 100 lbs at this point and decided to bite the bullet. We use for shifting and arm brake actuation. Might be using a cylinder for portcullis actuation at Howell - Jim’s working on something for this.
The arm has a 49:1 versa planetary into a double reduction gearbox 9.52:1. This was used over another planetary stage for durability concerns with this game. Then a chain reduction of 100:22. Saturday before ship we broke the teeth off the small gear in the 9.52:1 gearbox going over the rough terrain. Everything was replaced with steel gears before bag night and we started design on the brakes and a gas strut system. The rotor is on the gearbox output shaft before the chain reduction mostly because it packaged well, but it also gave an additional mechanical advantage to stopping the chassis. The main concern with that is chain strength - at Waterford we broke the arm chain on one side, and not just on a master link. We’ll see how it plays out, but chain is easier to replace than gearboxes and we have some redundancy.
Hang is powered by 2 x 775 pros into 3:1 planetaries belt driving lead screws in both arm tubes. We had an issue with driving the lead screws out the end at Waterford, but that was mostly code and is resolved now.
Intake is a 10:1 BAG motor with a 30:24 reduction in belt. Same motor powers the centering belts through a bevel gear.
Overall weight right now is 107 lbs. The shooter change may eat up 0.5 lb or so, so we have some room to play.
Main focus for Howell improvements will be high goal and lots of practice time.