That's it for now. Things to do for the future:
- Finish the top and bottom plates
- Finish machining the wedgelets
- Machine a slot in the wall for the weapon belt to pass through
I spent a couple hours in the machine shop this past week working on the UHMW unibody of my new beetleweight robot I've decided to name "El Tigre".
Drilling the holes in the top and bottom for where the top and bottom cover plates are going to be screwed in.
Milling out the pockets in the inner rails where the motors will slide in
Flipped on its side to drill the holes for the weapon shaft and mill flats for the nut and bolt head to fit into.
It was a little annoying to machine because the UHMW is so flexible and I had to turn the entire body on its side so it chattered a lot and isn't the prettiest looking. But the bolt that I'm using as a shaft fits great so I'm happy.
I also milled up a couple of blanks that will become the little wedgelets on the front of the robot to help feed opponents into the beater. These still need to be drilled and sharpened into a wedge shape.
Using a 1:1 scale drawing of the top plate as a template to cut them out of a sheet of Garolite. I haven't done a build progress update in a while, so I don't have any pictures of them actually cut out, but it was really easy to cut using a band saw and drilling the holes using the paper template as a reference.
With a lot of the machining done, I went home to start working on the electronics for the bot. I wired up the motors with the Vex 29s using this handy guide by Jamison Go on how to use these ESC for purposes other than the Vex kits they were designed for.
I forgot to take more pictures during the wiring process because it went so quickly. But it looks like I'll have plenty of space for everything, despite how messy it looks in this picture. All of the electrical components are listed in the original post. Only other thing to note is the 3D printed motor mounts I designed for this robot. They clamp down on the diameter of the motor right on the seam between the gearbox and the actual motor. This will hopefully help keep the motor together while being strong enough to hold the motors in place. With significant wheel protection and foam wheels I'm not too worried about it.
That's it for now. Things to do for the future:
I know it'e been a long time since I updated this. But between school and work I haven't had much time for combat robotic's lately. My schedule is starting to slow down so I'm starting to get back into building and competing.
As part of my 1st place antweight prize from Motorama I received a Fingertech Beater-Bar Kit with electronics. I've had the idea of a beetleweight beater style spinner in my mind for a while. I had a model drawn up in Solidworks as one of those ideas that I would build "someday". Well "someday" apparently turned into today. I adjusted my model and came up with this:
The design is based around a single piece frame cut from 2" thick UHMW by Big Blue Saw. I was very impressed with how their low-taper waterjet cutting turned out. It was basically identical to the model that I had drawn up.
Here is a looked at the planned insides for now:
Weapon: Fingertech Beater Bar Assembly
Weapon Electronics: Fingertech Beater Bar Electronics
Drive Motors: Botkits 22mm Motors
Wheels: 2.75in Lite Flites
Drive ESCs: Vex 29 Motor Controllers
Receiver: Spektrum AR400
Battery: E-Flite 3s1p 800mAh LiPo
More updates to come as the construction actually begins.
In the rush in preparing for the event, I slacked off on updating the website in favor of actually getting my robots ready for the competition. So here is what happened in that last week leading up to the competition:
When I last posted, I had blown the weapon ESC on Butcher. I got a replacement, the TZ85 from Hobbyking to handle the current a little better. This still caused some start up issues with the motor, so I decided to drop back down to my 4S LiFe batteries instead of the 6S LiPo that I had in there in order to avoid frying the motor or controller if it stalled on start up.
Now all that was left was to play some wire Tetris and squeeze everything back into the robot.
With that done. I had two days to pack up everything in preparation but I was ready for Motorama:
There were a total of 45 1lb antweight robots in the tournament this year. Double the number that were at Franklin Institute or Moto 2016. This made for a huge bracket and a long road for anyone hoping to grab first place. Hercules got a bye in the first round. Meaning it would have to win 6 fights to win it all.
Fun-Sized was a small drum spinner that Hercules faced in it's first fight. Hercules controlled most of this fight. The new grabber attachment allowed me to actually grab onto Fun-Sized's drum and push him around. He did get in a few good hits that eventually flipped Hercules over, but I won on a judges decision.
Viciously Circular is a vertical bar spinner, and Hercules's second opponent. This normally would be a bad matchup for Hercules as a big vertical spinner is likely to warp the lifter plate. After some dancing around there was one huge hit that left VC not spinning. Hercules got to show of its lifting skills by picking up and driving VC around the arena. Hercules won by tap-out to save VC's driver the embarrassment. I had hardened the lifter plate before the competition this time and it held up much better than the previous iterations after taking direct hits. There was only a few scratches and a small nick missing out of the plate after two fights.
Swamp Woman 2
Swamp Woman was a saw blade undercutter. This would be my toughest opponent so far. The large saw blade made it difficult to grab any part of SW without getting torn up. About half way through the fight he took out the 3D printed horn on the lifter plate of Hercules. But I out drove him for the majority of the match and won on a judges decision.
Hercules was a little chewed up. The wheels held together pretty well since I had put some silicon on them to add extra traction. The lifter horn was busted but I simply had to swap that out and it was good as new.
Discharge was a tough 3D printed, steel covered wedge robot. Unfortunately for him, it had been a little beaten up and I was able to get underneath of him a few times and control him. He got a few good shoves in but Hercules ended up winning on a split decision.
Foiled is a really interesting design. It uses a 3D printed, carbon reinforced hub on its weapon blade. This hub is shaped like a propeller such that when it spins, it provides extra down force to the robot. The downside of this is that there is less overall weight on the wheels, so it is very difficult to drive. I had to be very cautious of the powerful blade, but I managed to flip him onto his back a little over half way through. Because Hercules is so flat, I was able to squeeze under the disc and push him into the walls, sending him ricocheting around the arena. With an easy judges decision, Hercules was onto the finals!
Foiled won its way back through the losers bracket to make it to the finals to face Hercules again. This match went a little more evenly. Hercules took a lot more damage this time around. But I did manage to flip him over at the last second. The split decision went to Hercules, meaning Hercules went a perfect 6-0 to win 1st place overall!!
Overall I am super happy with how Hercules held up in this event. The UHMW unibody is a beast at absorbing impacts. I need to replace the wheels, wedge guards and lifter plate, but beyond that there isn't much else to do. I need to strengthen the servo mount I made and do something with the lifter horn to make it less prone to snapping off, but Hercules is still looking pretty great.
There were a total of 58 Beetleweights and 72 12 & 30 lb robots registered for Motorama this year. With the huge turnout they split up the Beetleweights into their own arena for the weekend. There were lots of very powerful spinners this year so it was going to be a tough road for anyone to get through the tournament alive.
Butcher's first opponent was Nothing Special. A fast wedge that was nothing special. Butcher got in a few good hits and then broke its belt leaving it weaponless. Nothing special got underneath Butcher and pushed it around a little until Butcher became high centered on its own belt. One disappointing countdown later and Butcher was in the loser's bracket.
Shake was a front hinged lifter that Butcher faced as its second fight of the day. This fight took way too long to get ready. We both had to use a postponement. I broke my removable link when I plugged it in for our first try and his left side of his drive train wouldn't work the second time. The third time around we had to make it work. Butcher got in a few good knocks and ended up seizing up Shake's drive for a knockout.
Army ants was a multibot consisting of 4 3lb "D2" kits. These kits do really well in the beetleweight class, but didn't fare so well in the hobbyweight division. Each bot was driven by a child of another builder. They all got destroyed but they had fun so I didn't feel too bad about it.
Minor Threat 3
Minor Threat 3 is a very powerful vertical spinner. I knew this was going to bee a tough match. Butcher had been having issues throwing belts so I had to only run the weapon at about half throttle. The plan was to attack the front right corner because I had a much bigger reach than he did. That worked for about 15 seconds until I hit the ceiling.
Butcher lost the belt and took some pretty nasty hits. But stayed together. I think the reason it didn't drive upside down is that the bot was getting high centered on the removable link. I plan on rewiring the whole bot with silicon coated wire to help prevent the solder connections from snapping under big impacts. Another improvement that needs to be done is to replace the threaded inserts with real nuts. The inserts held together for a while but stripped under big impacts because they are made of brass. Finally the biggest change I'll need to make for next time is to switch from urethane belts to a 2L V belt. I was prematurely knocked out of both of my losses due to a belt failure. That needs to be fixed for future version.
So I've been pretty busy lately and kind of forgot that I had a website. After Franklin Institute I had to get back to reality for a while and catch up on the things I had been putting off and building robots instead. I recently started a new Co-Op job though which means I no longer have homework for the next 8 months, so I have so much more time for activities.
My father and I plan on making our annual pilgrimage to Harrisburg, PA next week for Motorama 2017. This is set to be the largest Motorama yet with almost 200 robots registered! Because of the massive number of robots registered, unfortunately the beetleweight class filled up meaning I won't be bringing Barrel Roll. But that's okay, I didn't really want to have to rebuild that right now anyway.
This meant I had two bots to get ready, Hercules and The Butcher.
Hercules had almost nothing to fix after Franklin. The gears in the servo were stripped so I swapped that with a fresh one. The wedglet guards were a little dinged up so I made new ones. But spending half a day on getting a robot ready didn't feel challenging enough. So I went back and looked at the model I had to see if there was anything I could do.
I completely forgot that I had changed the model of Hercules already. I was really inspired by a similar robot, Flex. I decided to make a removable grabber attachment for Hercules. The idea is that as the servo pulls on the short side of the grabber making it rotate. When the grabber comes in contact with the top of another robot this locks the rotation of the grabber. The servo then continues its rotation pulling the lifting plate up.
This required making some specialized 3D printed parts:
From the top around clockwise we have a guard to prevent the wires from getting into the weapon motor on The Butcher, the lifter horn for Hercules's grabber, a new weapon motor pulley for The Butcher, and a servo holder for Hercules. I forgot to take pictures, but the grabber parts were just cut with a box cutter out of UHMW sheet and trimmed up on a belt sander. Here is a picture and a video of the finished product:
You can see that when it grabs something the weight is just a little too far forward that I don't have total control. I'm going to see if I can install some magnets underneath to help with traction on the steel floor of the Motorama ant weight arena.
Since the Butcher went undefeated at Franklin Institute, there were no structural parts that had to be redone, but the electric components were lacking. I didn't take many pictures of the build because I can't solder and take pics at the same time, but here is what the updated internals look like:
I upgraded the drive motors to Banebots RS540 motors, changed out the A123 LiFe battery packs for a single 6s LiPo pack, and changed the weapon system to a Turnigy Aerodrive SK3 1050kv outrunner driven by a Aerostar 70A ESC. Unfortunately this didn't work out so great.
While the drive motors worked much better, the weapon system stalled out. I tried to change the start up settings to see if it could manage and ended up catching the ESC on fire. Oops. I have a new one on order, but with only 9 days until Motorama, I need to get this fixed quickly.
Now that Franklin Institute is over and my life has settled down a little I figured I'd give an event report of how I did at the Franklin Institute event this past weekend. There was a huge turnout this year, with over 80 bots registered across 5 different weight classes it made for a crazy one day event. I had some ups and downs at the event but overall it was great fun as always.
Hercules vs Angry Erector Set
Hercules's first fight was against a horizontal spinner that was made out of some sturdy aluminum channel and had a FingerTech Chipper blade as its weapon. Hercules tanked a lot of the hits and flipped AES a couple of times. Half way through the lifter got stuck in the upright position. I out drove AES to win a judges decision. Unfortunately the reason that the lifter was stuck in the upright position is that the servo for the lifter had become dislodged and partially stripped the gears only allowing the lifter to go up and not down. Meaning for it's next fight I only had one lift before I was forced to rely on my drivetrain to win the fight
Hercules vs The Cuban
Because of the large number of competitors at the event, Hercules had about 5 hours in between its first and second fight. It's next fight was against a horizontal midcutter. At the start of the fight I rushed across the box to try and prevent The Cuban from spinning up. After some grappling and a couple of blows back and forth the belt came off of The Cuban allowing Hercules to win a judges decision using its one good lift to carry The Cuban across the arena and slam him into the wall.
Unfortunately this would be the last fight for Hercules. This fight didn't start until 6:30pm. Being that I had been at the museum nearly 12hrs at this point and was running on less than 5 hours sleep I was exhausted and decided to forfeit the rest of the matches and go home to get dinner.
I'm excited about how Hercules performed. I only have some minor things to fix for the future. It needs new wedge guards which is necessary after almost every event anyway. Since it's 1oz underweight I may make some out of steel next time to make it even sturdier. I plan on 3D printing some sort of servo mount to hold the servo in place better than the tape I have been using. I hopelfully will get around to making a tougher lifting plate this time. Whether that's out of titanium or heat treated steel, either of which will likely require stronger hinges rather than the hardware store ones I have been using. Other than that Herc is ready for it's next event since it took very little damage this time.
Oh Barrel Roll, why do you hate me. I had such high hopes for you this time. I had worked out all of your electrical gremlins. Everyone loves how you look. You have so much potential and fail every time. Before it even fought it had weight issues. I forgot to weigh it before leaving for Philly and had to change the front wedge to get down within the 3lb limit. And it only got worse from there...
Barrel Roll vs Mondo Bizzaro
BR's first and only fight of the tournament was against Mondo Bizzaro, one of the newest incarnations of Weta kits from kitbots.com. I never really realized how massive these things are. Barrel Roll is very dense, being made from all aluminum with a large steel wedge up front. Mondo Bizzaro dwarfed BR in comparison. I was confident going into the fight. I finally had control over my bot for the first time at an event. The fight started, we both rushed at each other. Mondo got under Barrel Roll and flipped it onto its back. In the process of trying to flip it back over Mondo Bizzaro got one good hit on the back corner of Barrel Roll and that was it. I lost all control of the bot. It was dead. I tapped out, defeated. Taking BR back to the pits it was pretty obvious what had happened
That one big hit from Mondo had bent the bottom plate enough to dislodge the wires that ran from one side of the bot to the other. The wires were loose enough to get caught in the weapon and be completely pulled out of the bot (see above right). This broke multiple wires and tore many others. With 2 other bots in the competition and the fact that I would essentially have to rewire a bot that took me 2 hours to wire in the first place, I would have to forfeit.
Barrel Roll is gong to have to get a redesign. I have been babying this original flawed design for too long. I will likely have to remake all of the body rails. The new one will have more space for the internals this time around because that is what has been causing all of BR's issues so far. I have plenty of ideas to work on for now including ways to keep the wires in check and reduce the weight so that is no longer an issue. But for now it's back to the drawing board for this one.
Where Barrel Roll failed the Butcher succeeded. Although it didn't have the stiffest competition, The Butcher went a perfect 4-0 on 4 straight knockouts to win first place in the Hobbyweight class
Butcher got lucky in the tournament draw, but I'll take what success I can get. It did have a couple legitimate knockouts and no major issues which I am very happy about. Here is the only video I have so far from the event of the Hobby finals between the Butcher and a 4-day build of a wedge, Freshies:
As you may or may not be able to tell from the video, the replacement motor that I threw in there was still too small for the size of weapon I am running. It took forever to spin up to speed properly. But when it was spinning it delivered some solid hits. For the future I'll need to put a bigger motor and bigger weapon ESC in there to decrease spin up time. I'll have to take some weight out of the frame to be able to do so which shouldn't be too much of an issue. But for now I am extremely happy with how it performed, earning Connbots first 1st place trophy!
Today I wrapped up everything that needed to be done on the hobbyweight to be able to get it ready for Franklin Institute this Saturday. The new replacement motor arrived in the mail. After going through 2 hacksaw blades trying to cut down the hardened steel shaft and cutting a giant hole in the top plate of UHMW, all that was left was the final assembly.
All said the weapon motor is still a little underpowered so I'm going to have to take it easy on the throttle this weekend, but it's as complete as it is going to get and I'm really excited about its possibilities.
Finally. Here is the all important team photo of all three bots before they look less pretty by the end of the day Saturday.
There are only 2 days left until Franklin Institute. I have been rushing to try and get everything done for these bots (man is three robots a lot of work). Unfortunately in my rush I didn't take a lot of pictures but I'll try my best to remember and explain what has gone on in the past week.
Last time I posted here, the Butcher was mostly done. I machined some spacers for the weapon assembly out of some 1/8" UHMW I had lying around. That was all put together (with the aid/distraction of my dog) and all that was really left was to make a belt and do some testing.
I don't have any pictures of the belt, but let me tell you, it's not pretty. I went through a long trial an error process of getting the belt welded together properly so it wouldn't come apart under its own tension and getting it to the right length so that it didn't pull too hard on the motor but still had enough grip to spin the disc. I see now why some builders love this and others hate it.
With the new belt in place it was finally time for some testing. In drive testing I came to realize that the bot seemed sluggish. It was only upon further investigation that I learned that the built in mixing in my Spektrum Dx5e transmitter limits the fwd/rev channel to 70% of full throttle. Without time between now and the event to get a proper mixer it will have to do. Next was weapon testing, which went even worse than drive testing...
In a big puff of white smoke I blew the windings on the weapon motor. Apparently it was not rated for the 4s LiFe I was running it on. With little to no time between now and the event I'm going to have to find a bigger replacement motor at a local hobby shop or else I won't be able to compete.
Jumping ahead a little I did some post machining on the drum for Barrel Roll. I reamed the center holes for bearing and countersunk the holes for screws to fit in. I took some time procrastinating doing homework to add some flair to the weapon discs with a little red paint. Updated pictures of Butcher will come later after I get the new motor. But for now here is how the updated Barrel Roll looks.
I think it looks awesome. That new disc is way more balanced than the one that I made in the wood shop in my basement. It should do some real damage this time around. The bearing that I added to the ear makes it so much easier to drive upside down and allows BR to self right like it was originally designed for.
With Barrel Roll complete and Hercules being done for some time now I am 2/3 bots complete for this weekend. Barring any other major issues I should be able to get ready in time and have a great competition.
It's been almost a week since my last update and I've been busy. With the event quickly approaching I had to squeeze in what robot building I could. Being gone this past weekend and next weekend for Ultimate Frisbee tournaments isn't helping either.
I finally finished machining the end caps for the weapon shaft after a lot of on and off work on them. The idea for these end caps was shamelessly stolen from another hobbyweight "Ripto Ultimate". The idea is to distribute the force of the impacts so as to not deform the relatively soft UHMW frame.
With the end caps done and looking great the next big step was to get the discs ready.
Each disc had to be drilled and teamed for the center bushing which took a lot of time and oil. Man is AR steel hard stuff.
With the disc complete and mocked up it actually looks like a real robot. The wiring is mostly done. Hopefully I can test the drive train later this week. Besides that the weapon motor still needs to be installed and I need to make some belts and spacers for the pulley system.
With less than 2 weeks to go it's crunch time. Hopefully it will all get done in time without any major problems.
I've been pretty busy lately but I've had some time to squeeze in work on robotics between massive amounts of school work and real world responsibilities.
I wired up Butcher late one night. This connector turns my 2 2s packs into a 4s pack. Well at least it was supposed to. I used the female connectors when they need to be male ones to connect to the batteries. This is probably why you should never solder things after midnight.
I got the discs back from the machine shop and they look great. The wiring is mostly done. So as it sits right now it weighs 11lb without the weapon shaft, end caps, and bearings. Hopefully I'll have enough weight left over for some wheel guards. At least that's what the CAD tells me.
Made a lot of progress in the past 24 hours. I'm slowly machining the end caps for Butcher that will hopefully be done in the next couple of days if I get time to work in the shop. The most exciting thing that happened was plasma cutting the discs for the pseudo drum of the new and improved Barrel Roll. They need some post machining to be usable but they look great for now.
I also finally have all of the electronic parts for the Butcher in. I'm going to try and wire it all up tonight or tomorrow and hopefully have a functioning drive train by the weekend. Just 3 more weeks until Philly!
My name is Michael Connerton. I am currently a mechanical engineering masters student at Case Western Reserve University. This website is a blog of my exploits into the world of combat robotics.