Barrel Roll had some issues in its first competition both electrical and mechanical. Mechanically it was a giant pain to fix. Because of its compact size and my lack of forethought, I had to almost completely take it apart twice during its firs competition. To remedy this, I remade the center frame rails with removable caps so that the drum could be more easily removed if needed.
Another issue was weight. I was .3 oz overweight at weigh in last time. So to correct this, I added more pockets to the rails to remove some weight. This left me just slightly underweight at 47.7 oz. Hopefully the scale at Motorama is close enough to my scale that I'll still be underweight at the competition.
Finally, the part I dread the most, the electrical issues. At motorama 2015 Barrel Roll was knocked out twice due to electrical issues.Part of the problem I found was that the heat shrink on my Fingertech switch had come loose and the system was shorting out on the frame. This was an easy fix, but not the end of the story. Barrell Roll had issues with going where it was told. Each of the motors would at one time or another spontaneously switch directions, which is not ideal when you're trying to maneuver around an opponent trying to tear you apart. After countless hours of trying to remedy this ( Recalibrating ESCs, rebinding, adding capacitors across the motors, switching receivers, switching ESCs, etc) I finally came to the conclusion that the BEC in my brushless ESC was acting up and would brown out causing the motor issues. Unfortunately during this process I accidentally shorted out the battery and fried my reciever. But besides that, all Barrel Roll needs for Moto 2016 is a paint job and it's ready
Over the past weekend I packed up my car and drove the 6+ hours from Cleveland to Philadelphia for the annual NERC Franklin Institute event. After having a summer of working and not being able to get away for robotics it felt good to be back.
This time I only had enough free time between school and other activities to bring Hercules, my antweight lifter. I found out that Hercules was pretty underweight (only 13.7oz of the allowed 16oz) which was mostly due to the fact that I had to print the body in PLA instead of the ABS that I had originally wanted because ThinkBox didn't have their ABS 3D printers ready since they recently moved locations. Hercules being underweight really wasn't my main concern though. I worried that the PLA would be too brittle to stand up to the rigors of robot combat, and my worst fears were realized in my first fight.
Hercules vs. Revy
Revy was the newest in the line of Kitbots combat robotics kits, an antweight vertical spinning drum, built by Brandon Nichols of Team Headbangers. Hercules was to fight Revy as the first fight of the event. I knew that I was in for a tough match that would require perfect driving especially since I was worried about the brittleness of the frame.
The first half of the match went just as I had planned. I kept getting under Revy and besides from one big hit there really hadn't been that much damage done. That all changed when the lifting plate of Hercules got stuck under the wall of the arena, mostly because I hadn't had much practice driving Hercules seeing as I had finished it 2 days before and it was much faster and harder to control than previous versions. Revy was able to get a good pop in to flip over Hercules. Hercules was reduced to a bad wedgebot and could do little to attack Revy. The match ended with Revy hitting Hercules clear out of the arena.
Revy had done some decent damage to Hercules, especially that last hit. But with a little acetone and super glue I managed to get it back to its original state (kinda). Hercules would drop to the losers bracket to fight another day.
Hercules vs Whack Job
Whack Job was a hammerbot that had suffered a pretty serious beating in its previous fight and had to forfeit its match against Hercules. Although its not technically a win I'm counting it as a win because I think that even if they were able to fight it out Hercules would've come out on top.
Hercules vs Saifu
For its next fight, Hercules was to face Saifu, the original antweight drumbot that the Kitbots kits are based off of. That's right, I basically had to fight the same robot that I had lost to in the first round again, this time with a better driver. Oh well, that's how the tournament goes sometimes.
Although I can't find a video of it, this fight went about the same as the first. Hercules was a little beat up from its first fight so pieces started flying off sooner. Saifu was able to completely tear off the right wheel guard of Hercules and deal a killing blow to that tire, knocking Hercules out of the tournament.
Overall, even though Hercules didn't do as well as I had hoped (1-2 on the day) I was happy. I think that if I can print the next frame of Hercules out of ABS it'll be much stronger and less brittle. I loved the new 11:1 Silver Spark motors from Fingertech and how Hercules was much faster and more maneuverable. I think with some slight modifications to the next version Hercules has the potential to be great.
In preparation for Franklin Institute I have been working for the past few weeks on Hercules. Like I said in my last post, I decided to go a slightly different path with this version and 3D print the body. I have access to 3D printers at my University's maker space, Thinkbox. They recently upgraded and moved to a new 7 story building with floors of space to build whatever your imagination can conceive.
I exported my Solidworks model into an stl to be able to print it out on the Makerbot. With an estimated print time of over 6 hrs I had plenty of time to study for my midterms. I had intended to go to a local competition near me (HORD), but between exams and other obligations I wasn't able to finish on time. Fortunately though, I had a four day weekend after midterms to relax (i.e. build robots). Because the University was on break, Thinkbox was closed, so I set up shop in my dorm room and got to work. Everything went pretty smoothly due to good planning and the fact that the majority of the internal parts were the same (the motors were switched from 30:1 GoldSparks to 11:1 SilverSparks and the servo was exchanged for a smaller metal gear servo).
Overall I'm very happy with how this came out. Hopefully the 3D printed material holds up to the stiff competition at Franklin Institue
I went back and thickened all of the walls on the Hercules drawing. It looks good but is still only .91 lbs according to Solidworks, so better, but not perfect. I also decreased the wheel diameter and went with a lower gearing on the Silver Sparks (2.25 -> 1.75 in wheels and 22:1 -> 11:.1 gear ratio). This should better protect the wheels while giving it a little more zip.
I think that I will leave the design as is for now, the extra weight allowance will just be a cushion to ensure that it's under 1lb with all the screws and everything, because as anyone who has ever designed and built something using CAD will tell you, it's never perfect. If I build it and it turns out to still be underweight I'm considering adding steel sheets to the outside to provide a little more durability, or maybe a sacrificial wedge that can be put on for some of the nasty ant weight spinners like DDT.
I hope to have this design built and ready for HORD on Oct. 17, but there's a problem with the 3D printing. My University is doing some remodeling so I won't have access to the 3D printers until Oct 1, which is cutting it close. But worst case scenario I hope to be able to at least bring Hercules, and hopefully Barrel Roll, to Franklin Institute on Oct. 24.
I've been away from combat robots for a while. I had a internship over the summer that left me with no time to vacation (i.e. go to events). But, with the return of Battlebots, the surge of discussion about robot combat has gotten to me and I decided to do what I can to get back into things. Since I couldn't actually compete, I turned to the next best thing, CAD. I went for a redesign of my most successful bot, Hercules, my ant-weight lifter. I had been bouncing around the idea of 3D printing a combat robot for a while and decided to go for it. The pictures below are my first try at it.
The internals are all the same for the most part, the one difference being I opted to upgrade from the Gold to Silver Spark motors from Fingertech. The big difference now is the 3D printed body. The overall dimensions are roughly the same, but the body is now one solid piece. The motor mounts are designed specifically for the Silver Spark motors to slide in. Each motor is prevented from rotating due to the oblong shape and is clamped in by a lid that is kept in place by two screws. There is also a mount for the servo to slide into. That will be kept in place by servo tape and the 3D printed lid (not pictured) secured by 4 screws.
I've been working on tweaking this design lately. The problem with the design pictured is weight. As shown, the bot would only weigh around 14 oz. Currently I'm working on beefing up all of the walls to make up for this, but feel free to comment on any ideas that you have on what to do with the extra weight.
This past weekend Team Conn Bots made a trek up to the cold, white north of Harrisburg PA for the largest robotic combat event this side of the Mississippi, Motorama. There were over 120 individual robots that were registered for the event and even more than that showed up.
We arrived early on Friday to grab a good table and compete in the Ant-weight class. Unfortunately the arena's were late on arriving due to a snow storm that had been moving through the area. After the truck finally arrived, many hands made quick work of putting up the arenas and getting the 30+ Ant and Fairy weights weighed and through safety.
Hercules vs Slim Pickens
In the first round Hercules drew the speedy wedge known as Slim Pickens. It was a close fought match, a real drivers battle. Hercules could always get under Slim Pickens but good driving made it hard to hold on and actually do anything with him. The match came down to a judges decision leaving Hercules the victor.
Hercules vs Algos
In the second round Hercules came up against the powerhouse of Algos from Near Chaos Robotics. I attempted to get around the extremely low front wedge but Algos proved to be too low. It was a close fight until one big hit stripped one of the gears in the Gold Spark motors of Hercules. It was all downhill from there. Algos finished the fight with one final pop that landed Hercules in the gap between the arena floor and the wall that has developed after years of abuse. With that Hercules dropped to the losers bracket.
Hercules vs The Ophidian
After the fight with Algos I had to replace the wheels and servo arm and put in back up motors into Hercules. Next I was up against the Fingertech kitbot called The Ophidian. After the first hit I lost one of my wheels and was left limping for the rest of the fight. Luckily I was able to get under The Ophidian and knock off his blade (which is a huge blade to run direct-drive off of a brushless motor with an 1/8" shaft). I was able to get under The Ophidian a couple of times but without half of a drivetrain there wasn't much I could do. The match went to a judges decision and it went for The Ophidian for the damage inflicted, knocking Hercules out of the tournament.
Hercules ended up (1-2) at Motorama, mildly disappointing but that's how it goes. Looking forward I think there are some improvements I could make: Making the front plate out of titanium to save weight, changing the servo arm to aluminum instead of plastic for stability, and using the extra weight to better protect the wheels from big hits and maybe even machining the body out of a single piece of UHMW.
Barrel Roll made its combat debut at Motorama 2015. The bot itself was somewhat thrown together last minute and I didn't have enough time to properly test it because all of my robots are at my home in Cincinnati and I go to college at Case Western up in Cleveland making it difficult to work on the robot. Despite all of that it came together and looked good in preparation of its debut.
Barrel Roll vs Trilobite
Barrel Roll's first ever fight was against the original Kitbot wedge, Trilobite. At the beginning of the fight the lack of time spent with the bot immediately showed. The weapon belt was loose thus causing troubles with spin up of the drum. Trilobite's extremely low spatula style wedge was easily able to get under Barrel Roll causing issues. I finally got the drum spinning but it wasn't for long. After a short time of spinning the loose belt came back again this time completely preventing the drum from spinning. From there it was a pushing match in which Barrel Roll was no match for Trilobite. Barrel Roll loses on a judges decision.
Barrel Roll vs Terrarpin
After the fight with Trilobite, I had a few things to fix, mainly the belt tension. With a donation from Kyle Singer of Twisted Sick Robotics I added an idler belt to the weapon drive and the drum was looking good. Next, Barrel Roll was to fight Terrarpin, a modified Kitbot. When the match started it looked good, the drum was up to speed and I was getting in some decent hits. Then all of a sudden Barrel Roll lost all radio control and shut down to get counted out for its second and final fight of Motorama.
I was pretty disappointed with Barrel Roll's performance in its debut. But they were relatively small problems that brought it down. For the future I need to fix the radio problems and the belt tension. I also need to make it easier to take apart, after have to basically take it entirely apart two separate times to fix the belt this is a must.
Barrel Roll is finished and ready for Motorama this weekend. Due to a last minute rush there aren't any progress pictures. But here's a grainy phone video to make up for it.
The front wedge was waterjet cut out of 1/16" 4340 steel. The top and bottom plates are 1/16" 6160 aluminum.
Motors and wheels installed. The drum is assembled and mocked up here.
Close up on the drum. UHMW center with steel outer ring. Hardened steel screws as teeth.
My name is Michael Connerton. I am currently a mechanical engineering student at Case Western Reserve University. This website is a blog of my exploits into the world of combat robotics.