13-03-2014 15:41

AdamHeard

Re: paper: 2014 HOT Tech Notes

Whoa. Pneumatics.

13-03-2014 16:02

Bryce Paputa

Re: paper: 2014 HOT Tech Notes

Love the design (and the pneumatics), but why only 50 pounds on the springs? Our design uses the same spring style, but 160 pounds which gives us a larger range and a flatter trajectory. Pretty much the same displacement as well. Also, how are your bearings set up? We tested with 80 pounds of springs and had no where near 15 ft of range.

13-03-2014 16:32

Pranit T

Re: paper: 2014 HOT Tech Notes

A really well thought-out design based off your priority list. Beautiful integration of the sub-systems. Good luck, Adam.

(The catcher arms remind me of 2056's robot arms from 2008)

13-03-2014 16:33

Mark Sheridan

Re: paper: 2014 HOT Tech Notes

Nice tech paper, i love the physic details.

13-03-2014 17:18

RonnieS

Re: paper: 2014 HOT Tech Notes

Great robot as usual Adam. You guys always manage to put together one hell of a robot and this year isn't looking any different. Can't wait to play with it at Lansing and MSC!

13-03-2014 17:41

Travis Hoffman

Re: paper: 2014 HOT Tech Notes

See, 2415? HOT already has cupholders on their bot.

Great job Adam and Team 67!

14-03-2014 10:30

TD78

Re: paper: 2014 HOT Tech Notes

Adam, fantastic document. I shared with my team...hoping they read it cover to cover like I have.

I am interested in that projectile motion spreadsheet. The document said it was posted on CD...but I'm not sure where (and I searched to the best of my ability!). Any way to share a link to it?

14-03-2014 10:58

JesseK

Re: paper: 2014 HOT Tech Notes

Interesting design analyses.

I thought 254's '08 bot was a much better bot to emulate for this year's game than 1114's '08 bot. Simple lift, softer launches and a similar roller intake/outake - much more controllable than a punch. I suppose c.g. would be an issue, but with the ball in the 'up' position c.g. is an issue with 1114's design too.

Turns out either would work for specific robots, but 1114's probably better for the high goal. Yet I was more biased towards being the best ball handler than the best high goal shooter.

Tom, here you go:
http://www.chiefdelphi.com/forums/sh...2&postcount=12

14-03-2014 12:49

Chris is me

Re: paper: 2014 HOT Tech Notes

I can't speak for HOT, but oddly enough this exact same logic is why we went with an 1114 claw. Building a bulletproof claw intake was way easier for us, and the rest of our design was driven around the claw.

Beautiful machine HOT. That backwards fire is so clutch, can't wait to see that win you some matches. Squeezing every second out of a cycle is key and it looks like you guys have it

14-03-2014 15:55

Ether

Re: paper: 2014 HOT Tech Notes

Here's another one:

Parabolic vs Air Drag Trajectory revC

14-03-2014 19:38

Ether

Re: paper: 2014 HOT Tech Notes

FWIW: Using the launch numbers in your paper:

28.5 ft/sec launch speed
46.8 degrees launch elevation angle
3.69 ft launch height

... and running an air-drag simulation assuming a 37.5 ft/sec terminal velocity for the ball resulted in very nearly the same ball height at 12.5 feet from the launcher.

http://www.chiefdelphi.com/forums/sh....php?p=1353376

15-03-2014 21:06

Mike Schreiber

Re: paper: 2014 HOT Tech Notes

We don't have any reason to shoot from farther out. Our shot gives us a range from about 8-18 feet. We focused on keeping the plunger super light so more of the energy can go into accelerating the ball and is not wasted accelerating the plunger. I'll get a better picture of our bearing setup for you when I'm in the shop, but you can see our outside bearings in the picture on pg 14. They capture the plunger on top and bottom.

16-03-2014 10:53

Adam Freeman

Re: paper: 2014 HOT Tech Notes

We like both designs as concepts to work from. But we felt that the 1114 design was superior (atleast in 2008) for both ball collecting and high goal scoring.

As Chris mentioned, we basically started with the claw concept and designed around that.

One of the biggest benefits we saw in the 1114 design was the ability to get balls out of tight spaces. It's still pretty true....but the top roller with out side bars does require a higher level of driver precision than the Bombsquad (top roller and side bars design). 1114 had one of the best drivers EVER in 2008. Teams should take that into account when they are evaluating designs from past games.

We will probably need to add something to our design to assist with ball centering to make it easier to collect the ball. Right now that is one of the areas we can improve on greatly.

17-03-2014 19:02

Jay O'Donnell

Re: paper: 2014 HOT Tech Notes

Great read. I always love looking at any robot 67 builds. You guys have made some great marvels of engineering and this year is certainly up to that standard.

17-03-2014 19:17

Chadfrom308

Re: paper: 2014 HOT Tech Notes

Thank you so much for this. When our team did terrible in 2013, I spent days looking over things like this. I ran into your tech notes and it was like I struck gold. I showed this to our head engineer and we decided to do what you did. We used waterjet 5052 1/16" aluminum and lowered the pneumatics use. We also did our own little spin by adding some mounting holes, cable management holes, and some strain reliefs built in to the chassis. We even had to buy our own 5052 stock because Chrysler (or fiat now ) only had 6061.

In short, thanks. This really helped us get a good base down to start tinkering with.

18-03-2014 08:09

Adam Freeman

Re: paper: 2014 HOT Tech Notes

Chad, thanks for the kind words...I'm glad that the tech notes are being used.

We were really impressed with your machine and driver's at Howell. Keep it up!

Looking forward to seeing you in Lansing.

-Adam

19-03-2014 18:47

tim-tim

Re: paper: 2014 HOT Tech Notes

Adam,

Thanks for sharing the Tech Notes again this year. I finally got a chance to read them, after watching some of your matches of course. It is always cool as an engineer to know how something works and some of the thoughts throughout the process.

Good luck the rest of the season and hopefully I can see this beast of a machine at Champs!

01-04-2014 08:38

Adam Freeman

Re: paper: 2014 HOT Tech Notes

Since we weren't able to finish our premier night reveal video in time, we waited until we had additional footage to publish a video.

Fresh from the HOT Team Promotional Department is a video featuring our robot at the Howell District: https://www.youtube.com/watch?v=pHBzLlr8aso

Additional videos from Waterford can be found here: https://www.youtube.com/watch?v=-AGQ...zK-g_bv4hkgwwd

Enjoy!

01-04-2014 08:56

Ty Tremblay

Re: paper: 2014 HOT Tech Notes

Good song choice. The last time I remember a team using that song in their reveal video they won The World Championship.

01-04-2014 10:04

Adam Freeman

Re: paper: 2014 HOT Tech Notes

Nice!!! I wish I could say that was intentional, but unfortunately that might be the only Robowrangler video I have never watched.

But, I am not suprised that us and 148 would choose similar music:
http://instagram.com/p/jUvPJGn23l/

30-07-2014 14:21

Adam Freeman

Re: paper: 2014 HOT Tech Notes

Finally got around to posting the CAD files: http://frcdesigns.com/designs-2014/

Typical CAD disclaimers apply...not everything is 100% accurate to competition robot.

This is the most complete CAD model we have created. But, most of the robot was designed in AutoCAD then Solidworks models were created to help find integration and assembly issues. We are by no means CAD/modeling experts.

Enjoy!

30-07-2014 14:34

g_sawchuk

Re: paper: 2014 HOT Tech Notes

Wow, this is a great set of notes. It looks great as well, super attractive cover page. I like how you laid out every step of your process including game analysis, concepts, and design. Fantastic work, and thanks for sharing.

30-07-2014 20:48

tim-tim

Re: paper: 2014 HOT Tech Notes

Thanks Adam, and HOT! First pneumatics, now CAD. Can't wait to dive into the design.

31-07-2014 12:37

notmattlythgoe

Re: paper: 2014 HOT Tech Notes

Adam, great robot this year. I look forward to reading through your design process and stealing ideas that we think will improve our process. Hope to see you guys again next year.

31-07-2014 13:06

April_robo

Re: paper: 2014 HOT Tech Notes

I love that I still read every word of the Tech Notes even though I know most of it. As a new mentor its nice to have these resources around. Thanks Adam love the robot and the team.

31-07-2014 23:57

MrRiedemanJACC

Re: paper: 2014 HOT Tech Notes

Adam, The step file looks great. Not so sure I'm glad I saw this, I won't be getting much sleep now!

It always amazes me how well designed your robots are and how you can push something right to the limit. The first thing I noticed is that you don't direct drive any of your wheels on the drivetrain. Is there a specific reason for that? Or do you just want to keep the weight of your Cims and gearbox centered?

Also, I am impressed with the 9 mm belts, seems like that is just too close to breaking, but I like that you were able to do that.

In the model it looks like you raised the outerwheels about 1/8"? Is that what you went with or did you need more and shaved the wheels a bit?

Thanks for posting this!

01-08-2014 10:35

Adam Freeman

Re: paper: 2014 HOT Tech Notes

We've used this chassis setup for a couple of years now, so most of it just carries over from year to year. At the start we decided that it was easier to leave the gearboxes centered for packaging and CG purposes. At this point we are comfortable with the gearing and chain/belt routing that we've just left them there. It helps us get a jump start on the season knowing we can get a chassis design solidified quickly so we can move on to more game specific components of the robot.

We actually switched from the 9mm belts to 15mm belts after we broke a belt practicing before the season. We had quite a bit of practice time on that belt and only one side broke, so I would guess something might have happened to that belt when it was re-installed (we had just replaced wheels before it failed). We ended up using 15mm kevlar re-inforced belts to ensure that we didn't have any drivetrain issues. We had the space and weight, so better safe than sorry.

The only drivetrain issue we experienced this year was picking up some debris in the drive that flipped the belt over and shredded it.

We stayed with the 1/8 raise on the outside wheels. We didn't shave the wheels, but the turning performance did increase as the outside wheels wore down. We had some issues throughout the season with popping the main breaker, which I'm sure the turning scrub had quite a bit of influence.

Overall we weren't extremely happy with the chassis performance from an agility standpoint, getting out of t-bones, avoiding defense, etc. We will probably do a complete re-evaluation of the chassis size, shape, # of wheels for next year.

01-08-2014 10:56

Andrew Schreiber

Re: paper: 2014 HOT Tech Notes

Was this a VP belt that snapped? I ask because we ran belts on our intake this year and ended up having to replace every single VP belt at least once. We had one non VP belt from a different supplier (SDP-SI?) and it survived the entire season. Trying to see if our experience was unique or if others have seen that the VP belts have a shorter lifetime than those of other suppliers or if there was something different between the runs.

* And anyone who is worried, VP belts are probably fine for anyone who does a sane season. 125's was NOT sane.

01-08-2014 12:33

DampRobot

Re: paper: 2014 HOT Tech Notes

We had frequent 9mm belt snaps in our drivetrain, and heard similar things from other CA teams.

01-08-2014 12:51

Adam Freeman

Re: paper: 2014 HOT Tech Notes

Yes, it was a VP belt.

We ran at least 6 other 9mm VP belts/robot that survived an entire season (2 on intake, and 4 on outer drive wheels).

I'm pretty confident that something else happened to the one belt that snapped. We had just replaced the wheels that afternoon. Right after that, they called me and said the belt broke. I think they tried to roll the belt on to the pulley and cut it, instead of assembling it correctly with the belt on the pulley.

01-08-2014 13:04

JohnFogarty

Re: paper: 2014 HOT Tech Notes

I've been analysing a lot of drive train design this summer and I've been meaning to ask since watching this year's Einstein matches. Where It seemed your drive had the worst time in escaping t-bone pins. Do you think there is a simple method to improving an 8WD to escape t-bone pins so that the power and robustness of the drive can be maintained.

The drop-down wheels that have begun popping up on various team's drives offers an interesting solution, but I'd just like to hear what you think.

01-08-2014 15:23

waialua359

Re: paper: 2014 HOT Tech Notes

We had an 8WD setup as well and T-bone pins were a problem at times. Besides the drop-down wheels solution, others employed the "hexagon" shaped frame perimeter. We plan to look at the drop down wheels as our 1st option for next season, if necessary.

01-08-2014 16:13

Adam Freeman

Re: paper: 2014 HOT Tech Notes

I agree with your assesment... I think we were extremely bad at getting out of t-bone pins.

I'm not sure there is a simple solution to the problem. I don't think the issue was only b/c of the 8WD drivetrain setup. I think that the combination of the 8WD, long chassis, rectangular chassis shape, and driver ability all resulted in us getting stuck in a lot of t-bones.

Drop down omnis are becoming more and more common. We entertained adding breifly them during the season (after MSC), but never really pursued it to far. It would have require quite a bit of designing and changes that would have only resulted in marginal gains at Champs.

We actually started running different combination of omni wheels in the offseason that helped a little bit, but we still had issues with pins.

As Glen mentioned, we will probably evaluate different chassis shapes to help lower the chances of a full on side pin. I think it will be a point of focus for our chassis design next season.

I don't think we are ready to add in drop down wheels to our drive system. Teams like 469 and 254 did pretty well without them on a standard 6/8WD setup. I'd like to see more of a square chassis setup next year and some better driving to avoid defense. We haven't entertained switching to 6WD much in the past couple years, but it might be something to look into next year.

01-08-2014 16:21

AdamHeard

Re: paper: 2014 HOT Tech Notes

This is all conjecture, but it looks like your chassis might have the ability to twist some vertically.

I've had a running theory for a while that a chassis such as that gets shoved into the carpet a bit odd under high defensive forces, contributing to the "locking up" affect.

Any thoughts?

01-08-2014 16:26

Andrew Schreiber

Re: paper: 2014 HOT Tech Notes

Could be a similar effect from what 33 noticed in 08 with the impact chassis rigidity had on their ability to turn (http://www.chiefdelphi.com/forums/sh...ad.php?t=68307) ?

01-08-2014 16:28

AdamHeard

Re: paper: 2014 HOT Tech Notes

Exactly, 100%.

My thoughts are it allows wheels that shouldn't be touching to be forced to touch, causing a wheelbase longer than you're supposed to be on. Combined with the already huge lateral forces from the defender, you're STUCK!

If only a bunch of teams would be willing to mount gopros to the underside of their robots for a few events...

It's interesting how the drivetrain arms race has evolved.

01-08-2014 16:31

Andrew Schreiber

Re: paper: 2014 HOT Tech Notes

It certainly makes sense that it'd be possible. Got a rigid chassis and a "noodle" chassis handy? Seems a pretty quick test to see if it's easier to tbone a noodle chassis.


I'd also be curious to see how it deals with omni directional drivetrains (mecanums or 33/78 style omnis). Guess I should get drawing FBDs.

01-08-2014 17:06

Re: paper: 2014 HOT Tech Notes

If I may request clarification - when you say "twist some vertically", do you mean the chassis bows upwards down the center parallel with the drive wheels due to lack of frame stiffness, and through this bowing all wheel sets are in contact with the ground?

01-08-2014 17:13

AdamHeard

Re: paper: 2014 HOT Tech Notes

Corners (with respect to the other corners) move up or down as the frame twist.

As for Andrew's request, we only have rigid frames

01-08-2014 20:21

MrRiedemanJACC

Re: paper: 2014 HOT Tech Notes

We have a flexible chassis from this year, for Andrew's testing! But we used mechanums and therefore we weren't as concerned with frame stiffness. I don't know for sure that is was a good idea though. I think the hard part was that the loading would change on each wheel therefore changing how it drove. We would keep contact with all 4 wheels though. Also in our third event we changed from mechanum to traction and kop wheels (4wd) to try to play more defense for other newer teams. Worked well, but not sure I'd do 4wd drive again. Too much power with 8 motors in the drivetrain and we tripped the main breaker in our last two matches.

It is interesting in the drivetrain wars, how much it has changed the forces the robots receive. There is much more involved than picking motors and gear ratios, the frame is definitely part of it and maybe the Bees were onto something with the Omni wheels. Maybe the frame doesn't need to be as stiff and that weight can be used elsewhere with the omni directional drivetrains. Or you have to go in the other direction of stiffness. It's always a tradeoff.

01-08-2014 20:52

Adam Freeman

Re: paper: 2014 HOT Tech Notes

Never thought about it that way. I would guess no, since the entire upper structure tubing was mounted through the chassis so I doubt there was much flex in the drivetrain. We had an issue during the build season where the claw was misaligned to the frame....it was almost impossible to flex the frame and upper structure to straighten it. We had to seperate components to get any movement.

But, anything is possible we've never looked at a corner to corner stiffness in the vertical direction.

My honest opinion is that we put ourselves in bad positions during the match which lead to a lot of easy t-bones for the defense.

01-08-2014 21:34

magnets

Re: paper: 2014 HOT Tech Notes

When some teams are in t-bones, their robot vibrates and shakes as its pushed sideways from the wheels getting and then losing traction with the ground, and it's almost impossible to get out of these pins. From what I've seen, it happens to robots that don't rock, like swerve (4 wheels in contact at all times) and 8WD (4 wheels in contact at all times).

I agree that avoiding defense is pretty important. We had issues with getting pushed in circles from the side and we had a traction limited 6 CIM drive with 2" wide McMaster blue nitrile tread on our wheels, like 254 does. 254 weighed well under 120 lbs, but didn't have too many defense issues because they were very smart drivers. 118 had a similar strategy. They were geared VERY high and had a single speed gearbox that would most likely trip breakers very quickly if they got into a pushing match, but they focused on avoiding defense, and it worked pretty well for them.

01-08-2014 21:36

waialua359

Re: paper: 2014 HOT Tech Notes

This past weekend, I got a chance to work with 16 as our partner at OZARK during eliminations. I took notice how easy it was for their swerve to just move away from a t-bone and drive away.
Even though we practiced a lot with 368, I never took notice because it wasnt a full field of robots and with defense from multiple robots.
Swerve is another direction we might move towards, as we tinker with drivetrain setups during the off-season. We already built a swerve back in 2009 but never implemented it into a real design for an FRC challenge.

02-08-2014 12:05

Andrew Schreiber

Re: paper: 2014 HOT Tech Notes

As you may have noticed watching "6" a lot of that is drive practice too. JT knows that robot really well and controlling it is almost second nature.

03-08-2014 11:24

RonnieS

Re: paper: 2014 HOT Tech Notes

This might not make a difference at all, but maybe so. When I find myself in a pin, I always shift into low and turn into them. It may all be in my head but every time I have tried turning away from the pinning robot, it seems as if my front wheels are on ice and my rear wheels are bolted to the ground. I really need to start testing these things aha. And it was a 6 WD WC set up using VP versa wheels.

03-08-2014 17:59

Adam Freeman

Re: paper: 2014 HOT Tech Notes

One of our previous driver/turned mentor said the same thing. But, when we tested it out just picking a direction and driving, with no turning, produced the best results. This caused both machines to spin until someone slipped free. Although, there was no guarantee you would end up going the right direction once you got out of the pin. Anytime they stopped or changed direction it took twice as long to get free.