Pop Goes the Monkey 12 Pound Robot


Home Our Team Our Robots Competitions Gallery Video Useful Links Discussions T-shirts Contact Us	Pop Goes the Monkey 12 Now that I have some time before the next competition I decided to tackle Solidworks to design the next bot. The goal is that I can use the software to design the basics to make sure everything fits and the robots weight will come in Ok, and then I can use the file to get the pieces waterjet cut. I'll still need to do quite a bit of drilling and tapping but I'm hoping that I'll be able to "assemble" it from the cut parts. Current Stats Body built of 3/8" Al with .1" Titanium Armor Wedge is the same, 3/8" Al with .1" Titanium Pneumatics use 1.5" cylinder. I don't expect it to have big flipping power but it should be able to overturn/flip an opponent. Drive will use 9.6v Harbor freight drills Currently the body comes in at 6.5lbs without the lid. I think I need to shave off a few ounces to make sure I make the 12lb weight. There are still several problems to solve. The biggest one is that I plan on having the wheels fairly far forward, which means I'll need to figure out the best way to keep the wedge to the ground since more weight will be behind the wheel than in front. I'm probably going to use magnets for part of it, but I think I try to use some sort of spring system to help raise the back end up without lifting the wheels off of the ground.	It took me about 15 hours or so to get use to using Solidworks to design this bot. Already it's proved very useful for making sure everything will fit inside of the robot. In typical Rob fashion, I didn't account for the thickness of the side-rails when I set the width of the robot. I had to do some trimming of the tank mounts to make get things to fit.
	Here is a picture of the wedge assembly. Things have changed a bit since I made this image. Originally it was going to have .375" AL under .1" Titanium. Even with the Al having big cutouts, weight was an issue. Now I've changed it to just .2" Ti up front which should be just about as strong and saved about a quarter pound.	Wedge Assembly
	In my earlier designs I had the hardest time figuring out how I was going to set things up so I could access the regulator to adjust the pressure on the bot. After pulling my head out of my butt, I realized that since the tank has an on/off valve. I didn't need full easy access to it all the time. I can still adjust the pressure but I'm planning on having it pre-adjusted to the desired PSI and simply turn the tank on/off with it's own valve. Although it isn't clear from these pictures, the holding brackets will clamp onto the tank and regulator via a screw.	CO2 tank and regulator assembly
	This assembly is of the servo-valve actuator. The servo is mounted below with the valve above. The servo will have a V shaped arm (not pictured) that will move the toggle switch on the valve back and forth. I've done this successfully in my 3lb bots.
	This is a current full bot picture. I've added a "horn" onto the wedge. This will help in self righting. I'm not sure if it will work, I'll find out how it works when I try it. The horn may be a bit flimsy against a big spinner so I may attach a stopper bar just beneath it.
	Side view of the bot
	Update: Sept 18th Good news The metal is finally cut and putting things together seems to be going as planned. I'm a slow worker, but with about 4-5 hours of work I managed to get 90% of the body of the robot assembled. Most of that time was in tapping the holes so the whole thing will bolt together. So far about 50 little 4-40 bolts. So far the body feels very solid but there is a little flex in the body. Once a lid is put on, it should stiffen up even more. I still need to assemble the wedge, it should also take 4-5 hours since there is a lot of drilling Titanium and still more tapping.
	I was was thinking I would need to put small blocks under the bot (near the wheels) to prevent big impacts from being transmitted back into the small motors, like when the bot flips an opponent. The Lynx motion motors seem to be fairly sturdy but they do have a small shaft. Luckily the mounts seem to have a fair bit of flex built into them. When I push down on the body the mounts bend inward. With the flexible mounts and soft wheels I think they should survive ok.
	Bad news I may not be able to fit the CO2 tank into the robot. When designing the robot, I messed up the high-pressure side fittings. The ones I designed for won't work. I am ordering the parts that I need but I don't think they will actually fit in the robot. There is a good chance that the tank will be riding on top of the bot which should be a fun target for Kevin!