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Pop Goes the Monkey (Version 1, Version 2, Version 3)

Pop Goes the Monkey V3.0
I think this will be the next-to-last version of this robot.  I decided on the general principal in version 2 and decided to improve on it and make it more reliable.  I used Solidworks to design the basic pieces and layout of the robot.  The goal is to have this ready for Robothon in early October but the 12lb robot is taking priority.  This version has AL side and wedge struts as well as .04 Ti armor for the sides and the front wedge.  I think it is still a bit big for all of the components but I'll find that out when I put the thing together.  If things go as planned I'll be able to use this design to make minor refinements and hopefully have thicker TI for the wedge for the "final" version.

Pop Goes the Monkey Front View
Solidworks picture of the robot.  The rear of the pneumatic arm has been moved to fit above the motors to reduce the overall length of the robot a bit.

According to Solidworks the robot base (entire body + motors and wheels) comes in at 2 pounds.  In a prior version of the robot the pneumatic system came in at 10oz, so this should leave about 6oz for batteries, wiring and the receiver.  I'll have to find out when it's done but I think it should come in at about 3 pounds when it is done.  Hopefully I don't have to do much "lightening" of the robot to have it make weight.

Pop Goes the Monkey Side View
Side View

This version still uses the relatively heavy Lynx Motion motors but since I already have many of them and the weight seems to be ok I decided to stick with them.  If I can't reduce the weight by an oz or two in the next version I'll probably go with smaller motors to beef up the front wedge.  .04 Ti is likely to get penetrated by some of the bigger spinners.

I managed to get the regulator and 12gram CO2 tank to fit crossways in the robot, near the motors and underneath the pneumatic cylinder.  This has freed up a lot of room for the rest of the components.  I think I'll be able to further narrow the front part of the bot in a future version.

The entire front wedge should flip up.  It is difficult to say how high it can throw another 3 pound robot but it should be more than sufficient to turn them over.  We'll see if I need to add a self-righting horn onto the wedge like I did for the 12lb version.

Pop Goes the Monkey Top View
Top View
Pop Goes the Monkey V2.0 (No pictures available)
I didn't get any pictures of this version, but it competed at da vinci days in 2005.  It was a more basic design with the wheels in the back and a flipping wedge up front.  It went 1 and 1 in the competition and the basic design seemed very promising.  It served as an inspiration for version 3.
Pop Goes the Monkey V1.0

Robot Characteristics

  • 2-wheel drive
  • Mostly made of HDPE and Garolite
  • Titanium Wedge on the front
  • Big-Pneumatic Pop!  I'm trying to make the weapon have as much bang as I can get.  My initial estimates is that it will be able to throw another 3lb bot 18" into the air.  I'm going to play around with the arm geometry to see if I can get this better.
  • About 1lb dedicated to the pneumatic system (not including the arm)
Progress Reports  
Friday May 13th,
Most of the pneumatic parts arrived a few days ago.  Last night I had a few hours to myself and was able to put the parts together to see if it works.  The pneumatic cylinder seems to have a lot of speed and force behind it but it is difficult to say since it doesn't have any load on it.  I got about 75% done with creating a flipping platform to test out different arm geometries.  Hopefully I can get it done by this weekend and start throwing things around!



Pneumatic Test Jig
By drilling different holes in the arm and wood pivot base, I can try out different arm configurations.
Sunday May 15th,
I finished the flipping platform and tried out a few different setups.  I didn't design it very well so it isn't as flexible as I'd like.  Also, I was having problems with the regulator and the valve.  I don't have the fitting to attach the pressure gage yet, so I wasn't sure what PSI it was running at.  If I put it up to high, the valve wouldn't work, too low it didn't have very much pop.  The fitting should arrive soon so I can fine tune it.  Overall the current setup is functional but not very exciting.  It threw a 3 pound block of iron about 3 inches above the tip of the arm, which reaches about a foot in the air.   So ~15 inches total, which is more than enough to tip an opponent over, but it doesn't have much exciting flip power.  I'll have to see if I can improve things.  The current weight of the pneumatic system is 10oz... I still need to add the servo for the toggle valve + the mounting of the components.  It should be easy to come in under the 1 pound that I had figured for the weapon system.
Close up of 5/8" cylinder Close up of Palmer Pursuit Rock the Boat regulator with CO2 cartridge
Close up of the 5/8" Pneumatic Cylinder Close up of the CO2 cartridge and regulator
Sunday May 22nd,
It looks like there will be a BBQ on June 18th at Fergs place so I need to get this puppy built!

The adaptor to fit the pressure gage to the system arrived, and after some messing around I finally got it to work ok.  I had to use some Teflon tape to seal up the connection.  Without the tape, the fitting slowly leaked air and prevented the pressure from properly building up.  Also, I may be having a problem with the regulator.  Sometimes it seems to fail to deliver any pressure to the system.  I have to slightly loosen, then re-tighten the cartridge to get it to work.  I'm not sure what is going on.  It may be the rubber seal is deforming and blocking the CO2.

More Pictures Soon
Tuesday May 24th,
I am tired of waiting for the SolidWorks program to arrive, so I decided to do it the old fashion way, with graph paper.  After designing what the arm must look like and what the body must look like to contain the components yet be as small as possible to save weight, this thing will look weird.  I'll post a picture of the detailed drawing, but I drew up a rough sketch in Paint.  With the arm mostly above the body of the bot, I should be able to enclose the internal components pretty well and keep the bots body fairly stiff.  I'm off to buy the UHMW today! 

Sunday June 5th
I spent some time this weekend on the robot. I'm hoping I can get it done in time for the June 8th BBQ.  The HDPE plastic was fairly easy to cut.  I cut out both of the side walls, and the arm.  The arm is a bit rougher that I would like but it should do.  This is a version 1 bot, so I'm not expecting it to be perfect.  The good news is that I messed up the weight calculations for the sides and arm, and they came in about 2 oz less than what I was expecting.  I may actually have enough weight to put a magnet on this monkey.
Pop Goes the Monkey
Here is a picture of the mounted valve.  It was actually easier to do than I expected.  The plastic mount will be easy to attach to the side of the robot.  The top of the mount is likely to stick out the top a bit, but it shouldn't be a problem.  With the orientation of the switch and how the servo needs to be mounted to activate it, I'm more worried about the hose sticking out.

One thing I did discover with more testing is that the single-barb hose connectors aren't really adequate for the higher pressures that I'm planning on running things.  Every little movement of the hose causes a small (but temporary leak).  I've ordered a bunch of 3-barb connectors which are longer and should provide a better seal.
Mounted Toggle Valve
I couldn't get a clear picture of this, I need a better camera for close up things.  This is the servo arm that will be mounted next to the valve.  I haven't tried it out yet, but I think the servo will have more than enough torque to move the valve.  If things are difficult I can always use a bigger servo. Servo Arm for activating toggle valve
Sunday June 12th
Here is a picture of the internal layout.  The CO2 cartridge has a plastic cradle that it's base fits into, then a couple of cable ties to secure it down.  The servo is mounted to the base and easily activates the toggle valve.  In this picture the electronics aren't yet secured.  There is going to be a bit of a wire nest inside the bot but It shouldn't be too bad to secure them down with some cable ties.  After some measuring problems, I also managed to get the drive motors mounted and wired up.  The offset output shaft and non-symmetrical mounting holes made it difficult.  I need to make sure I have more caffeine on the weekends. 
Inside Pop goes the Monkey
Here is a profile picture of the 80% complete bot.  It drives around and I can activate the cylinder.  The arm seems to return to the down position most of the time, but I still need to add some sort of elastic retract.  Also, when the arm is activated, the bot pops onto it's back and turtles.  I need to add some sort of bar to the back to prevent it from becoming immobilized by it's own flipper. I originally had a Garolite mount for the flipping arm fulcrum but it broke under the stress of the flipper so I replaced it with a huge hunk of aluminum.  80% complete
Currently the bot is 7 oz underweight, and that is with the HUGE battery 1350mh Li-poly battery that I'm using.  I may go buy a smaller one to save on weight and to more easily fit it into the bot.  There are still quite a few little things I need to do to get it ready, but the main thing at this point is to make the foot for the arm.  I'm going to cut back the
Garolite base a bit and fashion a metal foot to attach to the arm.  Overall the arm shape isn't quite right, so I may end up making a new one if this one doesn't hold up well in testing.
Lifting foot needed