The New 120

so...how about a picture of this bot of bots...the drum to end all drums.....

btw: we seem to get a bot within a few grams in SW and after it's built ...holy moly..it's within a few grams....actually, we just weigh typical wiring and connectors needed...but we do let sw calculate for the fasteners, etc.

I'll be posting some pictures as soon as the CAD has been finalized (most likely one week from today).

There were a few interesting changes with the overall layout: we're now using a two-wheel drive [which lets us make the whole thing a great deal more compact], and the front corners are ridiculously large ablative armor blocks. There's also great potential for future improvements in terms of components: there's enough space to replace the three NiCad packs with either lithium nanophosphate or lipo packs, with room to spare. Another nice bonus is many gigantic brushless outrunners have the same OD as long mags, the current weapon motor.

Lots of little details are being worked out at the moment - it's a combination of parts shopping and design finalization at this point. We'll be heading over to McMaster in not too long (it's local here which means NO SHIPPING COSTS!!!!) for some of our stock, and the rest will be from a variety of online vendors. The most critical parts we're hunting for now are the gears for two Whyachi TWM3M gearboxes - we integrated the gearboxes themselves with the frame to reduce overall size and weight. We're pretty sure Whyachi will be willing to sell us the sets we need.

Sum of All Fears (incomplete):

Conspicuously missing: Pocketing, front-corner ablative blocks (otherwise known as LOTS OF UHMW), the latest drum assembly (changes to teeth, mounting)

The full weapon CAD is now nearly complete, fasteners are the only remaining components to be added.

Current build with nearly completed armor & 95% complete drum. Note Gigantor UHMW Ablative Armor (TM) and steel front skids. Also changed is the exterior armor around the wheel, which is now a single piece of material.

Lookin good!

How much of this is actually made, and how much is changes in the design?

Reason I ask is cuz we got nothin built here at Ransom, but should start buying stuff and machining in the next week.

Nothing is physical yet, we're about a week and a half behind schedule. We're currently looking at a fully built robot by March 1st.

We've picked up the materials for Sum of all Fears, and as soon as the CAD files are prepped for waterjetting & the HAAS we'll start machining. As a side note, some grades of aerospace aluminum have very interestingly colored coatings/are very interestingly colored. I think we've got a sheet of 2024 that has this dark greyish-blue look to its surface.

Also, let's just say the schedule has shifted somewhat.

EDIT: We're looking to attend the Maker Faire tournament in May, and possibly one of the April tournaments (based on whether we're ready in time or not).

Weight issues are now mostly taken care of, we figured out we actually don't need the third battery - 5 lbs dropped right there. The first several part files will be ready to be fed into the HAAS & waterjet shortly.

How did you "figure out" that you don't need the third battery? By my math your drive system will digest about 125wh alone in 3 min. Two 24v 3ah battlepacks is 144wh leaving 19wh left for weapon consumption.

Also, if you're paralleling both packs you will not be able to spin up and drive at the same time.

5lbs out of the weapon/something else and into a 3rd battery would increase your effectiveness and endurance significantly.

Current IS torque, voltage alone does not get weapons spinning quickly.

We realized no one had actually done any really major calculations on power consumption yet, so we did them and realized we could get away with only two batteries. The reason why we did more in-depth calculations: Touro only uses two batteries (of identical properties to ours AND nearly identical electronics), while some other robots use three. We wanted to know why.

What lets us get away with just two batteries:

1. We're running the drive at no greater than half speed (via transmitter settings) - this both reduces power consumption and means we can actually control the robot instead of having a spastic mess.
2. The weapon can deliver 10 big hits a match (hits that bring the drum to essentially a full stop), which is also the upper limit of how many BIG hits drums deliver in a match. In addition, we don't intend to use the drum for the full match - just the beginning and the end. These are in general the most important times for the judges to see your robot working properly and dealing damage.

EDIT: (Critical assumption on the drive is that the robot is accelerating 50% of total match time)

Sometime this week, the first pieces of metal will hit the waterjet. The majority of the machining will occur during the last week of March/first week of April, and assembly will follow.

actually we should be starting today: Manual mill

We did a lot of work this Monday - A few of us did some tag-team work on the weapon shaft (reducing a 1.5" OD steel cylinder closer to the appropriate length), others filed down the waterjetted chassis parts, and another group worked on milling some of the armor pieces. More of the same this Wednesday.

Since we won't be attending any competitions this spring/summer, we've halted our progress to allow some of the other parts of RoboJackets (particularly the IGVC [Intelligent Group Vehicle Competition] team) to make better progress on their robots. The current plan is to have the robot done the first week of the Fall 2010 semester, when virtually all the teams we share machines with do no machining whatsoever.

did this one get shelved?

No, it's still moving along. We're seeing if we can get it ready for the October ComBots event.

A lot of posts about bots that seem to be total or almost total vapor....it would be nice to see you actually finish one of them??? Can we help?

idk they did a lot of machining with that sharpie bit till it wore out =P

rjw wrote:

A lot of posts about bots that seem to be total or almost total vapor....it would be nice to see you actually finish one of them??? Can we help?

You do realize I'm only one team member working on this thing, right? Add that with a recently ended summer semester during which 90% of the team was not on campus to work on the thing (seeing as many of us are either out of state or not from Atlanta), plus the fact that I'm not going to take photos of a slowly advancing pile of parts until there's actually something worth showing off, AND that Tech is an [in]famously difficult engineering school with a fairly hefty workload, and you can easily see why the build report hasn't moved very much. Sit tight and be patient, it's getting made.

Jeff L wrote:

Nothing is physical yet, we're about a week and a half behind schedule. We're currently looking at a fully built robot by March 1st.

From this and other posts (from January), I kind of assumed that you were actually building a robot in the near future.

I thought that Jamo was on your team...he usually bangs out a robot (albeit small ones) in no time whatsoever.

No big deal to me.....take your time

A bit more work has taken place on the robot, namely on the exterior armor around the wheel wells (primarily done on the HAAS). Some of our trickier parts are being handed off to the machine shops in the Mechanical Engineering department, which is better equipped to handle some of the more unusual components. One such example is the drum, which we can't reliably machine on club equipment. I believe virtually all of our remaining waterjet work got finished some time this past week though.

Unfortunately, we've had some setbacks that will prevent us from attending the competition this weekend in California. Primarily it's been machining mistakes (some our fault, some not - it's not always obvious when someone moves a vice on a mill and then doesn't indicate it back to 0), but we're definitely still aiming for the February Battlebots competition. If I can remember to, I'll bring a camera next time and get some shots of the chassis.