New Techniques

[Neil2012]

I had a talk with a few mentors on my team today, and were looking for new techniques and practices (interms of robot design and contruction) that we could implement. Also I'm supposed to design a robot implementing a few, if not all, of these ideas over the summer. Can anyone contribute some ideas?

[ttldomination]

Change can be good or bad...but in order to implement it, it's a good idea to know what you're going to change.

How about listing techniques that you're hoping to upgrade, posting robot images so people can post advice, or even searching for threads about some hot topics.

- Sunny G.

[Al Skierkiewicz]

Neil,
Start by planning an efficient electrical design. Centrally locate the PD and then distribute the power electronics in a star configuration. Think starfish and put the speed controllers at the end of the legs so that the motor leads can attache directly to the controllers without another connection in between. Plan for everything to be visible and easily changed.

[Hawiian Cadder]

My team did a similar review of practices, we changed a lot of our ideas about how to build a robot this year, and a lot of them turned out very well.

1) change from base plate, and 1/4 aluminum plate construction, to tubes rivets and gussets.

2) implemented CAN

3) changed from historically all bane bots on drive-train, to all andymark on drive-train

4) made an electronics box, that could be removed from the robot, rather than putting it all inside the frame.

i can say that all of these were good, but need better implementation, the frame was lighter than all of the plate frames we have done, it was faster to assemble, and easier to work on. the CAN had some problems, but we decided that in the future, we will try to use victors for any of the larger motors, and jags for the smaller motors, where more control will likely be needed. i loved our drive-train this year, it was fast, powerful and maneuverable, i was very happy with the tough-boxes and their performance. the electronics box was the only problem, while i still recommend having removable electronics, i think a box with the crio, digital sidecar / cars, and any other low current stuff in one box, and then another box with the motor controllers and other high current stuff.

if you do decide to make changes to your design, work them out preseason, research them thoroughly, and try to make them work well enough to set a new standard for your team.

[mwtidd]

Design for autonomous... then for endgame.... then design for teleop.

Historically speaking, autonomous tends to incorporate teleop into it, so by designing a robot simple enough to drive itself, it should be simple enough to allow the driver to excel.

Then the endgame is the most valuable part of the competition.

I think the traditional flow is teleop -> endgame -> autonomous and by designing that way you are almost always setting yourself up for time wasted when trying to make autonomous work, as you have designed a machine with the driver in mind, and many programmers will argue that this is the most difficult machine to program.

again just my opinion on the design flow, but I think by approaching the problem from a different direction can have a significant impact.

Also designing a robot for autonomous forces you to think about many of the things you may have assumed had you started with teleop.

This year we didn't do this, and our arm was completely variable speed based on the load on the motor. Had we designed for autonomous, a variable speed arm would have be unacceptable. Lo and behold it was a pain for the drivers to handle too.

[XaulZan11]

Originally Posted by lineskier

Design for autonomous... then for endgame.... then design for teleop.

I really think that flow is highly dependent on the game. In some years auto isn't important (2007,2009). In some year, teleop is far more important than end game (2008, 2010). Since I started FIRST, the most dominate robot/team was 1114 in 2008 and they couldn't do the end game of placing balls on the over-pass.

[Hawiian Cadder]

Originally Posted by XaulZan11

I really think that flow is highly dependent on the game. In some years auto isn't important (2007,2009). In some year, teleop is far more important than end game (2008, 2010). Since I started FIRST, the most dominate robot/team was 1114 in 2008 and they couldn't do the end game of placing balls on the over-pass.

i saw at least one match where they managed it, i don't know if it was luck though.

[mwtidd]

Originally Posted by XaulZan11

I really think that flow is highly dependent on the game. In some years auto isn't important (2007,2009). In some year, teleop is far more important than end game (2008, 2010). Since I started FIRST, the most dominate robot/team was 1114 in 2008 and they couldn't do the end game of placing balls on the over-pass.

I'll second this .

and rephrase my initial statement,
when designing a system think about teleop from an autonomous standpoint first (not the autonomous mode but autonomous maneuvers). how would you automate certain maneuvers and what design requirements would that create. Even if you don't end up automating these processes, just designing with automation in mind will make your system more robust.

[Neil2012]

Thanks! Those are great ideas. However, one of the major ideas discussed is an almost completely plastic robot. Our team recently got a 3D printer which makes plastic parts and now my mentor suggested a robot with parts that simply snap on. Has anyone ever tried or seen this before. Any tips on how this could be made to work?

[Andrew Schreiber]

Originally Posted by Neil2012

Thanks! Those are great ideas. However, one of the major ideas discussed is an almost completely plastic robot. Our team recently got a 3D printer which makes plastic parts and now my mentor suggested a robot with parts that simply snap on. Has anyone ever tried or seen this before. Any tips on how this could be made to work?

Plastic robots? See 1714. 3d Printed robots? I suggest against it. Unless you have some fancy printer the parts probably aren't as durable as they need to be and you can't print in large scales. This would limit what you are able to do. Is 3d printing a part a good idea if you know the material can hold up to the loads it will see? Sure.

[Gdeaver]

2 years ago our team looked into alternative materials. Plastics was one. We made a bending table and thermo-formed polycarbonate and polypropylene. We also vacuum formed poly carbonate chain guards. I like this video.
http://www.youtube.com/watch?v=hGBRi...eature=related
This year we made our arm out of fiberglass pultrusions. The methods of working with pultrusions are different than metal. Research and practice are needed for a team to work with pultrusions. We also made our electronics board and some other parts out of composites. Both S2 glass and carbon. Laying up composites is not something that you just decide to do week 2 of build season. Perfect summer research project.

[thefro526]

Originally Posted by Neil2012

Thanks! Those are great ideas. However, one of the major ideas discussed is an almost completely plastic robot. Our team recently got a 3D printer which makes plastic parts and now my mentor suggested a robot with parts that simply snap on. Has anyone ever tried or seen this before. Any tips on how this could be made to work?

Every 816 robot since 2008 or so has had at least one 3D printed part on in. Depending on the 3D printer you can make some really nifty parts and save yourself a bunch of time. Most common ABS 3D printers don't really print parts strong enough for anything that's going to see a lot of load, but they're really good for little things like spacers, sensor brackets, templates, etc.

[EricH]

The other thing to look into is the cost of 3D printing. When 330 looked into it, the cost of material used would be within the limits. However, the smallest commercially available quantity (what FIRST cost accounting is partially based on) would have been too much. However, costs may have come down since then, and different materials would cost different amounts.

As far as a "snap-together" robot...

I wouldn't necessarily do it, and certainly wouldn't try it without research or a prototype robot. The thing about snap-together is that it would have to lock securely and stay locked through impact. Start by building a prototype over the summer--material doesn't matter, other than you'll want to make it similar to what you might build in competition. Put it through the grinder--you WANT it to break under the stress of practice, due to the toughness of that practice. If it holds up, use it in competition. If it doesn't, figure out why it doesn't, and use that to improve the design or reject the design.

[Aren Siekmeier]

We 3d printed a custom sprocket for driving power chain for one of our elevator prototypes this year. The idea was to shove it up one side of a telescoping ladder as our lift mechanism. You can see a test with the sprocket somewhat visible at http://www.youtube.com/watch?v=50IzCFTdWtg. We ended up abandoning this design in favor of a serpentine belt design similar to 25's from 2007, but this was one of a few ways we used 3d printing. We also used it for all kinds of minibot prototypes, playing around with wheel sizes and shapes.

It's a great prototyping tool (hence the alternate name "rapid prototyping"), and can certainly be used for final components if the plastic will hold up. In both of those cases it would have worked great, but it wasn't legal on the minibot...

With some basic knowledge on the tolerances necessary for press fits, you could 3d print plastic parts or laser cut acrylic to snap together. But as Andrew said, the scale is limited. I think most polycarb needs a more powerful laser to cut (or does it cut at all?). Another cool thing you can do is print an entire gearbox with support material that you dissolve away, and then like magic you have a working gearbox, no assembly required. Granted this gearbox might need bearings inserted somehow, and probably couldn't hold up to much.

[ChrisH]

Originally Posted by EricH

The other thing to look into is the cost of 3D printing. When 330 looked into it, the cost of material used would be within the limits. However, the smallest commercially available quantity (what FIRST cost accounting is partially based on) would have been too much. However, costs may have come down since then, and different materials would cost different amounts.

There are several different technologies used in "Rapid Prototyping". They each have advantages and disadvantages. The technology Eric refers to above was Selective Laser Sintering or SLS. The powder used for SLS only came in packages that cost about $4k. That was several years ago and while I continue to be active in the field, I no longer worry about budgets so I have no idea what costs are now.

"3D printing" is often used to refer to a different process called Fused Deposition Modeling, or FDM. The raw materials are much cheaper and there are FDM machines available that a typical team could afford if they make a lot of use of it. I'm talking <$2K. You have to put it together yourself, but that is just part of the fun.