Motorama 2019 was a bit of a disappointment for me. As I'll go into in detail below, I lost a lot of matches for simple things that I easily could have fixed, or on close judges decisions. Overall Team ConnBots ended up 5-6 on the weekend. This was the first time in a long time I had lost more matches in a weekend than I had won. Luckily though, the robots came out mostly unscathed so I can simply fix some of the small failures I had and be ready for the next event I go to. As with my previous updates, I will update this post with videos of the fights as they come out.
The updated version of Hercules worked better than the previous versions, but it still had issues. The new grabber worked great, but even with the magnet on holding the back end down, I was unable to drive my opponents around. This could have either been a result of my under-powered drive motors stalling out when the combined weight of the two robots and the magnetic downforce were loading them or the wheels sliding on the incredibly dirty floor in the arena. I will have to do further testing to determine the root cause.
Pan Handler was a full body lifter built out of a dollar store dustpan. This was a really creative design. I love creative and different robots. Fortunately for me though, the plastic dustpan did not ride closely to the ground and I was able to get underneath him and push him around a lot, although I was never able to lift him due to the large, unique shape. This didn't matter as he couldn't lift me either. Hercules won on a judges decision.
Speed Wedge 1 was a 4WD wedge. It was having some driving issues and was significantly slower and less powerful than it should have been. This allowed me to get around and lift it multiple times. Although, as stated before, I was unable to drive around with the robot lifted in the air as I wanted. This still made for a good showing for the judges and was enough to get the decision to move on to the next round.
Ratfish is a very powerful servo flipper robot. I was pretty excited about this match as we have similar designs and it would be a good driving match against a veteran builder. Unfortunately when I turned Hercules on, the servo was not working and due to the tournament layout, I could not postpone our fight. This meant Hercules was basically just a floppy wedge bot. Since I couldn't articulate the wedge, there were several times where we ended up going head to head and he flipped me by going over the lifter plate, but under my side stabilizing forks, causing me to be tossed. I also could not adjust the claw when upside down, leading to me hobbling around the arena, upsidedown for most of the fight, waiting to be flipped back. Hercules lost easily on a judges decision.
Fire Arrow is another 4WD wedge bot that is well driven. I knew I would have to drive well in order to win this fight. There was a lot of back and forth grappling and pushing. I couldn't really get that good of a hold on him because he was mostly spinning wheels. In the end, the judges came to a split decision for Fire Arrow that I questioned, but the judges decision is final. And thus begin my hatred of Wedges for 2019.
In the end, I was relatively happy with how Hercules performed. I would have liked to have it working better but that mostly came down to time and practice before the event. Neither of which I had a lot of. While it had a relatively disappointing record on the weekend, It didn't face a single spinner weapon and is basically brand new still. I am hoping to find a local event in the near future to bring it to that I can continue to work out some of the issues I had.
Go Up was a 4WD vertical spinner from WPI robotics club. This was a well designed bot, but had a very tough match up in El Tigre. El Tigre ended up destroying the mild steel feeder forks and barely taking a single hit the entire fight. Tossing around Go Up for most of the fight, winning on an easy judges decision
Scrambler was a Kinetic Kit robot, very similar in style to El Tigre. While this is a proven design, I simply out drove them for most of the match. I got to their sides, knocking them around and eventually forcing them to tap out when their wheel hubs fell off and they were unable to move.
Weta is the original Kitbots vertical drum spinner. I was really looking forward to this matchup as it is a well experienced driver and bot. Unfortunately for them, Weta stopped moving second into our fight, without even making it fully across the arena. El Tigre won by knockout without even touching the other bot.
Nautiloid was a vertical disc spinner from Georgia Tech. I knew this would be a tough matchup for me as I coudn't really go weapon to weapon with him and would have to out maneuver him. Unfortunately, the weapon on El Tigre stopped working after the first hit. I later found out the set screw that held the weapon motor pulley on was completely missing, probably before the match even started. This lead to me trying to push him around for most of the fight. While El Tigre did well at this, the rather destroyed floor made it difficult and lead to him getting a few good hits in that swayed the judges giving El Tigre its first loss.
Mondo Bizzaro is a Kitbot drum spinner. While it looked the same as Weta, I knew this fight wouldn't be as easy. El Tigre was winning most of the match. It won a couple of weapon to weapon hits and jammed Mondo's weapon for most of the fight. When it became unstuck, he got a lucky hit that snapped my weapon belt. Turning the tide of the fight. I though I still had a good chance to win up until the last few seconds when I got stuck on my side after a big hit. El Tigre was counted out for its second loss of the tournament.
El Tigre was the one bright spot in a rather dissapointing weekend. The only robot I had that had a winning record and with its only two losses coming to the eventual 2nd and 3rd place bots. Both of which could have been easily avoided with some minor revisions. That being said, I think it is time to retire El Tigre. I am at the point at which three bots is too many for me to handle alone at an event and I would need to reinvest some serious money and time to remake El Tigre to where I'd want it to be. I will likely be selling it in order to help pay for future bots and allow the usable parts to not go to waste.
Butcher was by far the most dissapointing robot of the weekend. While most of the changes I made were relatively minimal, they were untested leading to two quick and aggravating losses for a robot that placed 4th at the same tournament last year. Most of this came down to luck of the draw of the tournament and a tough judges decision, but again, as with Hercules, it came out unscathed and will be able to fight again soon with few revisions.
Eulogy was a last second wedge that weighed in at only 7lbs. I severely underestimated it though as its relatively light weight gave it tons of driving power. I got one good hit in before he slammed me into the wall and I threw myself into the air causing my battery to come unplugged and knkocking me out for the loss. The extra room I added to the interior of Butcher for this year allowed enough room for the battery to shift and unplug itself on a big hit. While dissapointing, this was a simple fix. I was still confident as this is exactly how I worked my way back to a 4th place spot last year after losing my first match.
Splayed was a solid 4WD wedge. I was pretty upset with how the tournament bracket fell out as this was the worst possible matchup for me at this point. I knew I would have to take out their wheels without breaking my own weapon belt in the process. Thankfully, this time the batter stayed connected through a few huge hits. But eventually the weapon belt came off and I was forced to try and push my way out. Eventually one of the brushless drive motors gave out and we were both wriggling around the arena without doing much to eachother. I lost on a judges decision that, while fair, stung because I had done all of the damage to myself and thought I had fixed these issues already.
While this weekend was very frustrating for Butcher, I plan to do some minor tune ups and compete with it in another competition this year, wherever my job hunt lands me. Butcher took very little damage, only scraping some of the paint off of the weapon disk and blowing a drive motor. These are easily fixed and it will be ready to go in the future.
It was a bit of a mad rush in the last two weeks to get everything ready for Motorama. There were stressful and frustrating times. But in the end, everything is finished, on time. And I even had a little extra time to add some paint to make them look a little better this year.
With it now being February, Motorama is only 2 weeks away. I've been working hard over the past few weeks, but I still have a lot to go. Now begins the mad rush to finish everything in the next two weeks.
While not a lot changed appearance wise on Hercules, it has a lot of new little parts that need to be made to be able to make everything come together. I've made a lot of progress in the last two weeks, but there are still a lot of parts to be made.
El Tigre came together in the last two weeks. The main thing that happened was some weight reduction and adding traction compounds to the wheels. El Tigre is done for now, I might paint it later if I have time before the event. One down, two to go.
Butcher has been the slowest progress so far. I had issues with machining the body of the robot. I have to remake the UHMW bottom frame and spacer that connects the pulley and the weapon disk. I haven't done a lot on this since the last update, but once the frame parts are re machined most things should be easy to reassemble since most of the internals remained the same.
Hercules is going through a major rework for Motorama this year. The overall principle of the robot is still the same. But some minor tweaks will hopefully be improvements. The two major changes are the change from store-bought hinges to a custom hinge cut from UHMW, and using Banebots wheels instead of Lite Flites. The custom hinge set up improves the grabber geometry so it can grab, lift, and reset more easily. The change to Banebots wheels comes from the fact that my magnets got destroyed last year and mostly helped me in sticking to my opponents instead of the ground. This version of Hercules has lower ground clearance and firmer wheels in an attempt to remedy this and provide the down force needed to lift its opponents. In addition to all this, I switched over the robots electronics to all 2S LiPo (7.4V) in order to decrease the top speed of the robot as it was a little uncontrollable last year, and allow me to use a high voltage servo without the need for an external BEC.
El Tigre performed very well and for what the robot is (a body I designed around a Fingertech kit that I won as a prize) I was very happy with it and didn't feel the need to change much. The two problems it had were browning out under high current loads, and the motor mounts breaking. The brown-outs were a combination of me using an under-rated battery to save weight and under-rated connectors because that's what came with the battery. I replaced the old battery with a larger, higher capacity, higher discharge battery that used XT-30 connectors instead of the JSTs that were previously used. Secondly, my custom 3D printed motor mounts performed well until the end of the competition where I was thrown around too much and the screws all stripped out. I have added heat set threaded inserts to fix this. Both of these changes added weight to my design which was already barely under the 3lb limit, so I will have to do some weight reduction, but other than that it's mostly ready.
Butcher also did great at Motorama last year. Most of the things I wanted to fix after last event were things that I was planning on doing before Motorama 2018 that I just ran out of time to do. The biggest issue Butcher had was reliability in its weapon and drive train. The weapon reliability came from the issues I had with the belt not being the right length and having to adapt accordingly. This version included a proper length belt as well as the actual tensioner system I designed for the previous iteration. The drivetrain issues I had were because my over powered brushless motors kept melting themselves under the load. I dropped the battery voltage from 6s to 5s to help this as well as ordered new lower kV motors that should help.
I've been pretty busy with school lately, but I've used what little free time I have to finish up El Tigre. I unfortunately forgot to take a lot of pictures, but they would've been pretty boring anyway.
First, I finished milling up and drilling the holes in the wedgelets. I sanded them and buffed them so they were shiny because I can and it looks better this way.
I drilled some holes and tapped the Fingertech Mini Powerswitch so I could mount it. You can also see the silicon coating that I put on the wheels in this picture. The process for that is pretty straight forward. I used 100% silicone caulking, put a bead around the tire, and with the wheels spinning smooth it out into one thin layer with your finger. I put 3 layers on each wheel to give a decently thick coating to improve overall traction.
I also drilled out and tapped holes in the motor mount in order to mount the weapon motor to the inside of the front wall. I don't have a good picture of it, but I also went ahead and drilled a slot for the weapon belt to pass through the front wall from the motor to the beater.
It's not the prettiest, but the interior is completely finished. Everything wired correctly and mounted. I might put some foam in here to "shock mount" the electronics, but everything besides the battery is pretty light so I'm not too concerned about it.
El Tigre as it sits now. I added standoffs to the top so the drum doesn't hit the ground if it gets flipped over. The only things left to do now are to get a properly sized belt, clean up the top plates because they still have paper on them from layout, and probably give it a paint job.
As it sits right now it weighs exactly 48oz (3lb). I'll need to do some driving tests with the weapon running to verify that I won't need a bigger battery. If I do, I'll have to find some weight somewhere, but I'm really happy with where it is at the moment.
I was hoping to get registered for Motorama again this year, but registration filled up in 3 minutes! So hopefully I'll get in through a wait list. Otherwise I'll find a more local competition to try this out on.
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.
My name is Michael Connerton. I recently graduated from Case Western Reserve University with a master's in mechanical engineering with a focus in robotics. This blog serves as a record of my exploits into the world of robotics and especially combat robotics.