2016 HOTBOT

[Legator91]

Originally Posted by Michael Corsetto

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

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.

[Mike Schreiber]

Originally Posted by Legator91

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.

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.