As Motorama 2013 draws closer, and for once in a long time I actually have a robot done and tested, dammit!, I’m going to do something that I have not done since before this site went up in 2007. I call it an “opponent threat assessment”, and it… is pretty much that. It’s me sizing up the other entrants in the class I am competing in, based on their BuildersDB registration into, and thinking about weaknesses and strategies. I used to do this all the time back in my early battling days, but in recent history (some time around late 2006) I pretty much stopped thinking about it.
Well, that’s about when I stopped winning anything too. Hmm…
The cool thing about the OTAs for me, in retrospect, isn’t the planning and strategizing, which is something that is clearly susceptible to some cursory words and scribble without any real thought put into it. For me, when I did this often, the best part was simulating the match in my head – enacting various scenarios and responding to them. I’d started way back in 2001-2002 with pitting my favorite Battlebots (when Battlebots The Show was a thing) against each other. Watching hours upon hours of videos from local and builder-run events, too, back when broadband was still a big deal, also contributed to building up the models. In this way, by the time I got to high school, I’d already developed a fairly good mental ‘physics engine’ of sorts, since I thought about these match scenarios so often. I usually can, with fairly little effort, stare at a mechanism or mechanical implement and understand how it moves and how it would react to loads. It’s like a mental real-time FEA.
That’s one of the skills which I regularly wonder how you teach – my general opinion is that an innate understanding of mechanisms isn’t possible without many years of practice experiencing them. With each working or broken device you build up the physics engine better and patch holes in your reasoning. That’s how you eventually get to the point of just staring at something intensely and then knowing if it would perform in a given scenario. It’s also how I CAD – staring intensely at the computer screen while I run through maybe dozens of iterations of a design in my head before putting anything down on the screen (which would take much longer, so by the end of the process I’d probably have forgotten why I built a part).
All that is nice, but besides the point of this post. It’s just something that I wanted to get out of the way since in my recent forays into teaching and TA’ing mechanical engineering classes, I’ve realized that most peoples’ grasps of mechanical engineering concepts are superficial and very reliant on “monkey see, monkey do” kind of copying, or even worse (to me, anyway, perhaps not to my more analytically inclined colleagues) on extremely meticulous and detailed theoretical analysis which ignore real-world implications. While any method could provide a path for advancement and evolution, one of my goals while I’m here is to get undergraduate students to take charge of their own learning and build more things so they also build up strong mental analytical engines.
Anyways, without further ado, here’s the first OTA I’ve written down since maybe 3 or more website iterations ago. The basis is what’s available to me on the BuildersDB for Motorama 2013 in the Sportsman’s class, discussions on the NERC forums with fellow builderrs, videos of the bots in question from events past, or the odd I’ve-fought-this-guy-and-lost experience. This is also assuming the bot doesn’t just fall victim to One Loose Wire syndrome early on…
Despite not being pictured on the DB, I know everything about this bot since I’ve pretty much seen it built in front of me. Blitz is in the interesting position of also running RageBridges with DeWut?!s. Why? Because Adam and I are really the people behind the pile of stuff on Equals Zero Designs. The whole damn thing was basically started as an excuse for us to get better parts we couldn’t find elsewhere. Clocker and Blitz are therefore very well matched in speed and tractive force. Blitz’s weapon is a Sewer Snake like dual-hinged flipping arrangement that can throw opponents forward and over (see its first version build midway down). I’d say that Clocker is vulnerable to any attack which can flip it over, not because it’s not invertable, but simply because rolling back on to all 4 wheels takes a precious few seconds. I’d have to avoid being broadsided – a position which Clocker has no defenses against, and I can get continually pushed around in. Because the lifting forks extend out far ahead of the bot and Clocker is known to be very stable even with a 30lb opponent hanging off the fork, a head-on attack might even be my best option. Blitz is fully invertable, but the doubly-hinged weapon would hinder mobility if it’s upside down, a position which I could try and maneuver it into just by using the fork as a flipper. The greatest threat comes from its speed, which is greater than Clocker’s by about 25%, and the widely-placed lifting fingers, which can easily result in a broadside attack if I’m not careful.
DM is a bot I’ve battled before with Clocker in 2010. For this year, the description on the DB reads “Going back to version 4″. Through investigating the builder’s website, “version 4″ is in fact the bot pictured on the DB, and its weapon is a “reciprocating spike”. Besides spikes being actually an ineffective weapon in the combat robot universe, the bot itself is also rather boxy and has no other pushy features like wedges or lifters, and apparently poor inverted performance. I’m anticipating a match filled with much grab-and-go, since its ground clearance also appears rather high. Based on the published build pictures, the drivetrain is not as powerful as Clocker’s, and will probably max out at around 12-15 miles per hour, typical of most cordless drill drivetrains. So short of a spontaneous system failure, I anticipate being able to both outmaneuver and dominate traction. I’m hoping to execute Clocker’s fairly well known spin move with DM if given the chance.
Gigarange is a bot I’ve seen in action personally and on video, but haven’t fought. It’s a classic 4 wheel, low profile, 4-bar lifter bot, similar to Test Bot except less wedgy due to the Sportsman’s class rules. Based on the most recent videos of Gigarange at the Franklin Institute event, it’s quick and maneuverable, but I think I have a speed advantage. Its front lifting plate is much narrower than the span of my forks, and the robot is overall boxy and low. I’m fairly certain I can get ahold of it through a frontal attack only. Again, as with all pusher-lifter opponents, I’d want to drive to avoid a broadside attack, but because his lifter is fairly narrow, I may be able to escape from it by rotation – that is, just driving quickly forward and backward if I begin getting pushed sideways. One weakness of Gigarange I’ve observed is that the lifter is fairly slow to act. Hence, again, I may be able to avoid traction breaking using speed alone. The basic strategy would be to attempt to flank to avoid the lifter arm, but if that fails, try attacking full frontal using lift only (to break traction). I’d want to not plant the upper clamp arm on top of its lifter because it can extend with enough force to potentially damage the clamp and actuator (the clamp arm having almost 8:1 leverage on the actuator).
4. Jack Reacher
I’ve been watching the progress of this bot on the NERC forum for months. The bot is one of the few new flywheel powered flipping weapons around, and despite its complexity, the builder is known for reliable designs. Based on test video posted recently, the flipping weapon definitely has enough punch to potentially 360-flip Clocker on a good shot, but more likely, it will just toss me over. I’m rating the bot high in threat just because it can flip and drive reliably (based on my assessment of its drive motor choice and wheel choice/mounting method), which can be bad news for me if I get bowled over and cannot escape in time. Conversely, the complex flywheel machinery may make for vulnerabilities I can exploit by bringing the fork or clamp down on it. The flipper’s geometry is also one I can exploit – instead of “popping out” like many designs, it hinges back such that the majority flipping action occurs at the end of its lifting plate. Hence, if I were risk-oriented, I might actually try grabbing it by the flipper since the actuation motion would try and kick the robot up, rotationally, instead of flinging. My course of action would be to try and bluff the driver into triggering the flipper into an empty shot (e.g. by attacking, but retreating quickly), upon which I would try to either get under the whole bot or attempt to lodge the clamp arm in the flipper. JR can self-right, but with difficulty and only by propelling itself along the ground a few feet based on its test videos, so if I can trap it backwards and upside down in a corner, it will have very little recourse. The worst case failure mode is being flipped upside down, but I hope to be able to recover from the position before JR is able to reload (a process which takes a few seconds as it spools up the flywheel).
I’m unfamiliar with both the bot and the builder, and the CAD image posted on the DB is not too helpful. If it’s as described, then I’m going to have to watch out for the spring powered hammer. Clocker’s top armor is definitely a bit deficient, and there are some components sticking up unarmored such as the clamp motor and perhaps the big fork gear itself. Without knowing anything else about how K-onstant drives or loads the hammer, I cannot really make an accurate threat assessment about it. I’m rating it as a high threat because in the event it does work great, I will need to spend most of the match playing defense to avoid the hammer. Against hammer type opponents, I really can only rush them while the hammer is cocking or reloading, hoping ideally for some kind of broadside or up-ending attack with the fork. The best case is trapping them upside-down, with the weapon fired, preferably against a wall, so they have the least chance of being able to self-right
LU is a design I am unfamiliar with, and I don’t know the builder either, but it does have a fairly comprehensive CAD rendering on the DB. The trouble is that I am not very threatened by said drawing. For a lifter, its wheelbase is awfully short and its ground clearance appears limited. The lifter, unlike Gigarange, also does not appear to run the entire longitudinal dimension of the bot, so there is plenty of space for me to plant the clamp onto. The bot seems rather easy to high-center and break traction because of its very short wheelbase compared to bot length. The only issue would be if it were very fast and well driven – but even so, I think I can approach it head on and break its traction with the inner fork tines first (if the bot’s dimensions are roughly what I think they are.
I think I fought Nyx at least 5 times at Dragon*Con 2012. The match will be completely dependent on driving – the two bots are essentially 1 for 1 in speed. Nyx had a unique ability to wedge itself using its lifting spike between the fork and frame of Clocker and prevent me from lifting, but at the same time trapping himself on the fork. The match will also be dominated by who has better traction as a result. Because of his lifting spike, I can’t approach him head-on like with flat plate bots. Instead, an intricate series of flanking maneuvers (see all Nyx matches in the D*C2012 video) will be needed to get the forks under him. I’m counting on the arena being enclosed this time to hopefully up my unpredictability in maneuvers and intend on using the walls and corners if possible. If I can hook one of his fairly wide and open side rails with the fork, then I have more leverage as a result. I would have to drive to avoid broadside and rear attacks especially – Nyx has fit very well exactly behind Clocker in the past, and with this build not having changed widths all that much, it will still be a vunerable spot.
I watched this bot being built on the NERC forum, and I’m not really sure if the rail of saws will do much damage. Unlike many newbies’ beliefs, saws aren’t that effective in combat because to do damage, you need the opponent to stay still, something which rarely happens. I do expect that Palindrome can do the most “flesh damage” to Clocker, since spinning saws are spinning saws, but unlike many other opponents it has no capability of pushing or wedging. The weapon is also driven by an easily stallable brushless motor and runs in solid bearings, so it could bind very easily. The strategy with Palindrome would just be to grab and go. I do hope to parade him around the arena and mark up the walls or floor. The bot also has a broadside vulnerability something which I hope to be able to exploit because its speed potential does not appear to be great (using DeWalts in low gear, though with large wheels).
Phoenix is a quick and maneuverable flipper bot which I have seen dialed in recently – it was seemingly unreliable in the past, but now it consistently flips 30lb opponents and can also self right handily. Because of the length of its flipping arm ahead of the bot, I’m going to have to avoid any engagement directly, or allow broadsiding. The arm reload cycle does take some time, during which it is raised up, so I could potentially bluff a flip, then attempt to lock the fork under the arm to block him from reloading. Clocker drives much faster than Phoenix, so I should be able to maneuver as needed. Another potential strategy is to keep the fork slightly up, over the height of the body of Phoenix, and attempt to hook his lifting arm at the top where the cylinder attaches. The body of the bot is also short enough to allow a broadside grab. Overall, I’m still rating Phoenix as a high threat because of the potential to flip Clocker over handily if I miss a beat.
10. Such and Such
Based on the previous version of S&S and recent Facebook photos posted by the builder, S&S is again a “horizontal clamper” – the whole bot expands sideways using a multibar linkage in the center, and can clamp down on you from the side. It then uses dominant traction to corral you around. This year, S&S is actually a “shufflebot”, or a pseudo-walker that uses continuous cam legs, with what appear to be rubber blocks for legs. Walkers are afforded a 50% weight advantage, so S&S may weigh up to 45 pounds. While Clocker could lift it, I’d have to make sure to grab him on a long side (so the bot’s weight is not substantially leveraging more than an average 30lber) but that, of course, risks being grabbed in return. I do think I still have the traction advantage, however, and definitely a speed advantage because of his shuffling nature. As a result, so long as Clocker doesn’t mysteriously fail, I don’t think I can do poorly against S&S so long as I keep driving and avoiding the hug of death.
11. That Robot
There’s not enough information on the DB regarding this bot for me to really make a call. Allegedly it has “spinning arms”, which puts it already into the gray zone of Sportsman rules. Clocker is built fairly solidly, so if “spinning arms” does become a real thing, I hope to be able to back into them and stop them. Otherwise, the bot’s design sketch tells me it’s not invertable. I’ll have to wait and see for this one
This year, Tyrant returns with an actual chainsaw attachment. Trouble is, I don’t think it will do that much damage – it’s not geared very highly, and like all saws, will probably bump and skip off a moving opponent. However, in the name of the class, it will put on a GREAT show I’m sure! Another one of those perennial n00b weapon suggestions is a chainsaw, so many people in the audience ought to identify with Tyrant. Because it has no pushing implements and big exposed wheels, I’m going right at him. In fact, I kind of want to try grabbing him by the saw. Tyrant is quick, however, and the chainsaw is sure to win aggression points from the judges and audience, so I’m going to have to control completely (Complete Control style!) or risk losing by decision.
Upheaval is the bot which has pretty much won every Sportsman contest there’s ever been. It’s reliable, packs a massive punch, and well-driven. It also has front drive wheels, so it can really just turret around and wait for and of your maneuvers. I fought it in 2010 with Clocker Remix to predictable results. This time around, I should have actually functional drive motors, short of a spontaneous failure (which is always a potential factor). Clocker is now much faster than Upheaval, but his turreting means I’ll have to be clever in my approach. The basic strategy would be much the same as fighting Phoenix or any other flippy bot – try to bluff a flip, then get under him while the arm is reloading. Clocker has many apparently solid spots up front which I could use to my advantage – the fork will tend to slip its clutch if a sudden force is applied, and the springy legs will hopefully live up to their name . Alternatively, as long as I can keep rolling him over (not grabbing), he’d have to waste shots having to self-right, and I could potentially try and trap him against a corner that way, making self-righting impossible. As long as I can keep moving and poking, I should be able to avoid being flipped. The most important part for me would be to never, ever drive across the flipping foot and never engage directly.
Basic strategy for Clocker also goes something like:
- Try using the fork as a lifter first, to leverage the opponent off the ground, then grab only if needed
- Don’t body slam people backwards – Clocker may not be able to exit this position, requiring a two-robot unstick pause in the match. Maybe only do it for effect at the very end of a match if needed.
- Drive slowly and methodically unless I need to run – recently my “stick twitchiness” has gone up due to me being seriously out of practice. I hope my practice driving with Clocker has been able to resolve it
- Avoid being broadsided at all costs – Clocker Remix had that weakness, and Clocker Advance has the same long flat sides.
- Drive upside-down to escape a flip if needed, don’t try to self-right on the spot.
Hope this all works out! I’ll be leaving for the tournament in an hour or two, and hopefully tomorrow there will be a live report from the event.