Over the summer I have been working to get Hercules and Barrel Roll set for their next competition. This week I finally got them both running, which is unfortunately one week too late to be able to compete in Bot Blast which was this past weekend. But that just means that I have more time to prepare for Franklin Institute.
Getting Hercules ready mostly entailed just moving everything over from the old version to the new UHMW unibody. Besides drilling a few holes and trimming the body here and there, I didn't have to do much in the way of construction. As pictured above, it only weighs around 14.5 oz which is just enough weight to put on some aluminum guards for the wedglets.
The body of Barrel Roll has gone virtually unscathed in it fights so far, mostly due to the fact that it couldn't drive in the direction of its opponent. At it's last competition, Motorama, I determined once and for all that the issues it was having was from radio interference. To fix this I removed the electronics and swapped the motors out because the old ones had some metal shavings in them which possibly could be causing the motors to produce emf which interfered with the radio. This helped a little, but was still not a solution. I added a pair of capacitors to each motor from the leads to the can to ground them. These combined with a capacitor in between the leads, for a total of three, would theoretically reduce the feedback from the motors. This finally fixed the radio issues that BR was having. Unfortunately this led to the discovery of more, albeit more minor issues. When I designed Barrel Roll, the ears on top were supposed to allow me to be able to flip myself back down to a proper orientation, in theory at least. In practice BR doesn't have enough traction to do this so I will have to come up with some way to remedy that. Also, the drum that Barrel Roll has on it now is okay, but it's only as balanced as the wood shop in my basement allowed. When spinning up to about 2/3 max speed it wobbles quite significantly. When I return to school I will have access to a machine shop again to make a better "drum", although I think the name wont be as catchy anymore...
For the next evolution of Hercules, I am sticking with the unibody design, but changing materials. The newest body is cut from a 1" thick sheet of UHMW using a ShopBot CNC router.
I'm happy to announce the newest addition to the team, The Butcher. The Butcher is a 12 lb horizontal spinner, my first 12 lber, sponsored by my University's maker space, Think[Box]. The body of The Butcher is CNC routed on Think[Box]'s ShopBot. Here are the planned features:
Body: Layers of 1/2" CNC routed UHMW through-bolted together
Batteries: Custom 4s A123 battery pack
Reciever: Spektrum AR400 Reciever
Wheels: 3in Colson mated to Banebots Colson Series 1 Hubs
Drive: Banebots RS395 Motors mated to P60 20:1 Gearboxes
Drive ESC: BotBitz 30A ESCs
Weapon: 10in tip to tip horizontal disc spinning at up to 7,000 rpm laser cut from 3/8" AR400 steel
Weapon Drive: Eflite 1100-10 brushless motor at a 2:1 reduction
Weapon ESC: Eflite 40 amp ESC
I will be working on the internals over the summer. I won't have a chance to work on the mechanical parts until next school year since I will be off campus for the summer. The goal of this robot is to be able to compete at NERC Franklin Institute in the fall. Hopefully all goes to plan.
This past weekend Conn Bots traveled to Harrisburg PA for the annual NERC Motorama Robot Combat event. Being the day before the main event we spent a few hours helping to set up the main arena. Eventually we were far enough along to start weigh-ins and safety checks. Hercules weighed in at exactly 1lb 0.0 ozs. All together there were a total of 18 ant-weights registered. Fights started around 2pm
Hercules vs The Ophidian
For it's first fight, Hercules was to face the robot that knocked it out of the bracket last year, The Ophidian: a Fingertech Viper Kit with the spinning blade attachment from Team Revelation Robotics. I was slightly worried facing a spinner as my first opponent, not knowing how the new 3D printed ABS body would hold up (especially considering last time).
Luckily for me, after box-rushing The Ophidian, his blade stopped spinning, leaving it to a shoving match that I was sure to win. Hercules won on a judges decision while sustaining only minor scratches.
Hercules vs DDT
For all of the competitions that Jamison and I have competed in together over the years I have had Hercules, I had yet to face him until this day. Going in I was slightly more confident knowing that Hercules had held up against a decent horizontal spinner in the Ophidian, but this was different. DDT is the most powerful 1lb horizontal spinner I have ever seen in action.
The first big hit between the two tore off one of the steel wedge guards on Hercules. Hercules held up pretty well to most of the hits, only losing small pieces here and there. Jamison got in a few good hits that broke off both extensions that help Hercules lift other bots reducing it to a push bot. Hercules lasted the full 2 minutes and made it to a judges decision but lost decidedly to DDT.
Despite the severe damage that DDT doled out I was happy with how Hercules held up. Part of the problem was the fact that DDT's blade was the exact same height as the screws I had put in place to hold on the spring steel covers for the wheel guards. This resulted in Hercules losing its left steel cover. The second picture above shows the power that DDT has in that blade. It sliced through .02 in spring steel, tore our a black oxide screw, and tore through 3/8" of ABS to bend the hinge on the lifter enough to disable it.
Hercules vs Kate the Rat
After dropping to the loser's bracket thanks to DDT I had to try and make some repairs. I re-riveted on the lifting plate with new hinges and expoxied one of the arms back on. Hercules's next fight was against Kate the Rat, a 4WD pushbot with lots of speed. Using what was left of Hercules to push around Kate the Rat I won on a judges decision but lost the arm I glued back on in the process.
Hercules vs Buzz
After a long wait due to postponements, Hercules's 4th fight of the day was to be against the drum spinner of Buzz. Hercules has always struggled against vertical spinners (see Hercules vs Algos). And although I probably would've been fine running right-side-up, since I had lost the arms already, I decided to err on the side of safety and run Hercules upside-down as a wedge. This wasn't the best decision, as you can see in the video, because I got stuck a couple of times and had to readjust the angle of the lifter to get better traction after a hit.
A little pushing and shoving here and there, mostly going my way. Buzz ran into the wall about half way through and broke his weapon motor. This gave Hercules the advantage to keep pushing him. Buzz eventually got stuck in the crack between the wall and the floor, but showed enough movement that I had to keep fighting him, leading to Hercules getting stuck in the gap. In the end Hercules would win in a judges decision.
Hercules vs Vile Ant
For it's fifth (and final) opponent of the day Hercules would face another brutal horizontal spinner, Vile Ant. Going into the fight, I didn't have high hopes. Hercules was on its last legs, and another high KE spinner was the last thing it needed.
Almost immediately, Vile Ant finishes what DDT started and rips off the other steel wheel guard, followed closely by the ABS underneath it. Hercules kept fighting, and made it all the way to a Judges decision. It ended in a split decision for Vile Ant who would later advance to the finals against Algos
After its bout with Vile Ant Hercules was pretty shredded: Missing 2 arms, 1.5 wheel guards, 2 gearboxes barely attached to their motors, and a barely working weapon. In the end though, I'm very happy with how it performed, getting to the final 6 of a field of 18 and being the only non kinetic energy bot to do so.
Thoughts for the Future:
Although this version of Hercules did much better than the previous blue PLA version, I think that it is time to give up on 3D printing (at least for this bot). Even the Markforge Carbon Fiber/ Kevlar impregnated Nylon that Jamison uses has the same toughness (ability to absorb energy) as the UHMW that Hercules originally used. While 3D printing has its place, this design, because of its reliance on the two front arms to balance the lifter, is not suited for it. For the future I plan on abandoning a 3D printed unibody in favor of a CNC milled UHMW unibody. I believe this will provide Hercules that toughness that it needs to face the massive amount of spinners out there.
I'm really at a loss here. I thought I had fixed it, I really did. I went through the steps, replaced everything, isolated the problem and worked to fixed it. Barrel Roll was working before I packed it up and put it in a box to fly to Harrisburg. Friday night I brought it back to the hotel in order to bind it to my transmitter and get in some driving practice before the big day. Unfortunately, the same problems showed up again. Barrel Roll would intermittently get a mind of its own and start spinning in circles, turning the weapon on, or generally doing whatever I wasn't telling it to do.
Barrel Roll vs Super Veloce
After the driver's meeting I was less than optimistic. I had spent hours the night before in my hotel room trying to fix the same problem that I had spent 2 weeks on prior and still not solved. I tried what I could in the pits but it wasn't enough. Barrel Roll still was being rebellious. Fortunately for me it was to face the wedge of Super Veloce; unfortunately it was driven by Ian McMahon, a very good driver, and I was barely able to drive. At lest I knew I wouldn't get destroyed.
This actually went a little better than I was expecting. Super Veloce was able to get under me for the most part but I was able to get in a few good hits for the portion of time I was actually in control. You can see a couple of times in the video where I completely lose control and Barrel Roll starts spinning in circles. At one point it even drives itself off camera and into the arena wall. The good news is that the weapon actually works pretty well. Hitting the wall too many times busted the bearings but I had spares so that's not an issue. The bad news was that without having control of the bot I was unable to maneuver to hit my opponent and was basically at the mercy of my opponent. All of that uncontrolled spinning in circles lead to one of the wheels coming loose. All of that lead to Barrel Roll losing a decisive judges decision and dropping to the losers bracket.
Barrel Roll vs Quicksand
Even after more tinkering in the pits Barrel Roll still wasn't working right. I had conceded to the fact that I wasn't going to get control of the bot without taking it all apart and reevaluating the electronics setup.
Barrel Roll struggled even more in this fight. I was barely in control. Once it got knocked on its back, the sporadic movements became even more of a problem. I'm going to have to go back and take out the entire electronics system to be able to fix this problem. It has to be some kind of interference with the ESCs/receiver. Luckily the entire body is unscathed so it's only electronic issues I have to fix.
All in all I'm pretty happy with how I did at Motorama 2016. Hercules performed great and is only going to get better. Barrel Roll, while it has its issues that need to be worked out, finally showed some potential in the small amount of time that it was working properly. I have some time until my next competition which will probably be sometime this summer if I am able to get enough done while in Wisconsin for my internship. Until then I have plenty of things to work on.
After Franklin Institute Hercules was pretty banged up. With a record of 1-2 and that win coming from a forfeit I was less than happy with how it had performed. The biggest problem that it had was the body, being printed out of PLA, was way too brittle for combat applications. To fix this I printed the new body in ABS, which I had originally planned to do but simply ran out of time.
The new body is basically the same as the old one, a few tweaks of dimensions here and there. I moved the mounting holes for the lid away from the corners to help relieve some of the stress from big hits on the front arms.
Transferring the electronics from the old Hercules was pretty straight forward. I forgot to print new motor cover plates, but the old ones were unbroken and I liked the blue anyway.
One of the major weaknesses of Hercules, especially with the last iteration, has always been wheel protection. As you can see Saifu got a pretty serious hit right on the exposed shaft of one of the motors after the wheel guards had been shattered, bending it out of shape. To combat this, I took advice from "the kids from MIT" and wrapped the wheel guards in a layer of .02" spring steel. This should help absorb big impacts and prevent the wheel guards from breaking as easily.
After adding the new lifting plate all I had left was the arm guards, but after weighing it I discovered that Hercules had about 1.75oz to spare. The old aluminum wheel guards weighed only about .5oz so I figured I would use the extra weight to upgrade to steel.
Well, I may have gone overboard a little with the steel. It's definitely way thicker than it needs to be. But after some careful trimming Hercules is now exactly 16oz (according to my scale at least). If I'm overweight on Motorama's scale I can remove some screws and drill some holes in the steel and I should be fine. With both of my bots done, all that is left is a cool new paint job.
My University's maker space, Think[box] (http://engineering.case.edu/thinkbox/home) is taking applications for sponsoring student projects so obviously I am going to submit an application to build a robot. It will be a Hobbyweight horizontal disc spinner. The body would be made using the cnc router in Think[box] to cut layers of 1/2" UHMW. Here's some more details:
Body: 5 layers of 1/2" UHMW CNC milled to fit electronics
Disc: 10" tip to tip, cut from 3/8" AR400 steel (approx 3000J)
Weapon Motor: EFL 10-1100 Brushless at ~2:1 reduction
Weapon ESC: Eflite 40 Amp Lite Pro Brushless ESC
Drive: 395 motors coupled with Banebots p60 20:1 (8.3 mph max)
Wheels: 3"x 7/8" Colsons
Drive ESC: Botbitz 30A esc
Battery: 4 a123 cells in series to give 14.4V 2500mAh pack
Hopefully I will get good news from them in the next month or so. If not it will just fall into the archives of imaginary robots in my laptop.
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.
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.