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Thread: 4WD Front Hinge Flipper - Featherweight

  1. #61
    Quote Originally Posted by James Williams View Post
    Yeah I just realized you'd have less than 3 weeks until Colchester. Are you going to Robots Live in Stevenage or Extreme Robots in Chatham, they're both on the same weekend.

    Colchester and Stevenage

  2. #62
    So it's been a while! Will probably start a new build thread in the next few weeks, so rather than leave this build diary unfinished, I think I'll conclude it with a very late recap of my experience of the KoB champs. I'm not very good at writing but I'll give it a shot!

    -PART 1-

    Last time I posted here, Strix still didn't have a working weapon, so that's where I'll start this off. Getting this flipper going was turning into a total nightmare. Unfortunately bad turned to worse as I killed yet another HIWIN linac just 6 days before I was due to leave for KoB. DARNIT!

    So by this point I had admitted defeat - although I had an untested gimson linac, I did not have time to mount and modify it. Guess I'd have to either drop out or go into this weaponless...

    Well, the robot combat gods had other ideas. Basically, for several months, I had kept my 2 other dead HIWINs for spare parts. One of which was potentially still usable, but the plastic nut which moves in/out was stuck. Despite countless efforts to screw it back down the threaded rod, it just kept chewing itself up.

    For whatever reason at like 11pm, I guess as a random act of desperation, I decided to dig this thing out and try to twist this nut back down again.

    And I have no idea why, or how, but it actually worked! First time, too! The nut re-aligned itself with the threads of the rod. Like... what? How!? What did I do different this time?? I was legit speechless.

    With just 2 days before I needed to leave, the flipper was finally working:



    Rory's arduino sketch limits the speed of the motor quite a bit, but even then it still had more than enough grunt to tip over Venator.
    I tried to add on 2 extra horns so the robot could self right, but unfortunately it didn't quite have enough travel to tip the machine over. I just had to hope that in the heat of the moment, the weapon would have enough momentum to self-right properly.

    As you can see in the vid though, Strix is not painted at all. So I had to do a complete disassembly the day prior to the show in order to paint the wedge and apply the stickers. Strix looked like this night before, and I had to turn up at Insomnia with the robot in bits:

    Strix in bits.jpg

    So going into Insomnia I was totally knackered, relieved, but above everything else just feeling like the luckiest person ever, as just 48 hours earlier I was 100% convinced I wouldn't have a working machine.

  3. #63
    -PART 2-

    So yeah, the first morning at Insomnia was pretty insane, but I managed to get Strix fully put together with time to spare so I could wangle a locking bar out of a chunk of hdpe. Strix weighed in at about 12.8kg. Half an hour before my fight I had a quick test of the drive and weapon - all was good and ready for my first match!

    I was drawn against Amnesia and fellow Scots, Elevate. I was very concerned about Elevate - from reading their build diary it looks like a gorgeous yet deadly machine. Unfortunately due to technical difficulties they had to withdraw from this match. Amnesia on the other hand was 3rd last year, it would be tough but I reckon I could have a ding-dong in the arena with it.
    Entering the arena I started to power on Strix. Drive worked fine, but the weapon.... Nothing. Nada. Diddly squat. I had no idea why this was happening because just 30 minutes ago everything was working fine. Also, due to how my locking bar is fitted, the flipper was stuck wide open, with all of Strix's spaghetti wiring hanging out all over the place. But whatever, I'm here to fight.



    It quickly became clear that Strix wasn't really up to the task. Adam completely outdrove me, and Amnesia's wedge was much lower than Strix's. These black bearing boys wheels barely had any traction either, so despite being 4WD over Amnesia's 2WD, Amensia was still much quicker. After a few exchanges Amnesia pinned Strix against the arena wall for a quick KO.

    So back in the pits I do a diagnosis. I think the arduino just decided to die. On it's own. Which it has never done before. Oh well! I was just gonna have to go into this next match without the arduino/limit switch setup and be very twitchy with my transmitter!

    My next fight was against... Uh oh... Shrapnel and the Calabash Brothers (I never managed to tell the Chinese team, but if you are reading this, I love the name of your robot!). I know Jarvis has talked about this fight already, but here it is from my perspective. Jarvis admitted he was more wary of CB than Strix (quite rightly tbh) and so my plan was to hang back, and try to play the two big spinners against each other. If I could distract CB while Shrapnel came in for the kill, or drive CB from the side into Shrapnel's spinner, then I could have a chance.
    And the strategy went surprisingly well!



    After a few quick jabs from Strix, and some sick spinner hits, Shrapnel eliminated CB early on. Shrapnel then tossed Strix over, but for the first time the self-righting actually worked! I think purely because there was no arduino to limit the speed of the brushless motor! On the bad side though, the flipper conked out again. Shrapnel's spinner also broke down, and so it boiled down to a wedge fight. Strix was able to out wedge Shrapnel, but the big hit earlier damaged one wheel, meaning my drive, which was already pretty pants due to poor traction was made even worse. As a result Strix couldn't really do much, and the judges gave Shrapnel a well deserved win.

    Back in the pits, and it turned out that one of the gears of the actuator had sheared it's teeth. But I had a few spares, so it was an easy fix. The wheel didn't take long to repair either - just a bit of epoxy resin and it was alright. Ready to go for qualifying match 3!

    Vs Straddle and Tempest. Oh dear I didn't get the best draw.... In all seriousness though I was really looking forward to this match. Strix is designed to take on mean horizontal spinners like Tempest, so I thought this would be a good test. I needed to win by KO here or else I was out, so I was ready to go full force in this match and really take the fight to these two big spinners.

    So I'm loading Strix into the arena, heart racing, nervous as heck. Locking bar is fitted, in goes the links, robot has powered up fine, all good.
    And then finally... On goes the transmitter.
    ...
    Wait, what? I said, on goes the transmitter. Nothing. Nada. Diddly squat.
    My Dx6i transmitter died on it's own, and I had to forfeit the match. To be honest, at the time I was gutted. I'd rather Strix was totally obliterated than have this happen. But that's the way it goes - you win some, you lose some! Here's the fight anyway, since it is an awesome hit!



    And with that Strix was out of the competition, finishing with 4 points.

    Overall I had an absolutely brilliant weekend, even though Strix's performance was quite underwhelming. I can only attend one or two events per year, but every time I'm floored by how kind and friendly everyone is. Also turns out that the arduino failure was actually down to my TZ85 ESC which has been faulty since new, which also killed a grand total of 4 receivers that weekend. Big, special shout to the 6 other roboteers that either helped diagnose the problem or lent me parts after I was eliminated. (David, Gareth, Alex, Mark, Craig and Felix. I think that's all of you!) Thanks to them, Strix was able to enter one last whiteboard fight. And once again thanks to robo challenge for having me!

    IMG_4570.JPG

    So what happens to Strix now? Well this iteration is going to be retired - the wheels and linac really hold the machine back, and the chassis needs to be redesigned in order to accommodate changes. But more on that in another build diary. This probably isn't the most engaging write up ever - I don't usually write this sort of thing, and let's be honest my robot didn't really work that well, but I hope it was somewhat interesting. Cheers for reading!
    Last edited by dotDominic; 16th September 2018 at 23:05.

  4. #64
    good seeing it work. i find the fact I helped you get it working the Tag Team just to pin you into the side wall XD

    you got a good design just refine it.

  5. #65
    Seems you had a run of real bad luck, but I think Strix is a fine looking machine, and if the linac behaved it would have been a different story...

    On the plus side, no damage!! Have you looked at that moulding compound a few others run for tyres? iirc it's about £15 for a tube, that and a new linac you should be good to go again.

    I always secretly hoped for a wedge off against this when mines finished

  6. #66
    Cheers guys - yea the electrical gremlins weren't kind to me this year, but on the flip side it was a miracle that my weapon even worked at all.

    I must admit it is quite tempting to upgrade specific parts instead of making a whole new Strix. But there are still a few more issues with this design that I know I can improve. The poor ground clearance means I can forget taking this to ER live shows, and I really, really want to do an entirely custom linac, which I don't think I can fit into an already cramped design.

    Hahaha well, I'm always game! I reckon it'd be a good fight if my robot actually worked!

    Also, no Mark, I haven't forgotten....

    IMG_4571.jpg

  7. #67
    why can't you fit the custom Linac in the current design?

  8. #68
    I echo what others have said - if you get the remaining minor issues ironed out, Strix will be a fine machine! I don't think it will take much work either.

    I never got to fight it so you have to keep it running so that I can

  9. #69
    @Mark Well basically if I keep the same chassis design I'll always be stuck with roughly the same amount of actuator travel, which negates one of the main advantages of going custom. Also, the HIWIN one just barely fits in the current design.

    But tbh the main reason is the wheels. If I increase the size of the wheels (to up the speed) I need to remake both the bulkheads and armour panels, and potentially the baseplate. And if I increase the ground clearance, the wedge or flipper will need to be redone as well so they touch the ground. I guess this is the disadvantage of going 4wd.

    I just feel like if I have to remake so many parts and compromises in order to make this robot better, why not just start over and make this design how I want it? Plus Strix's performance was really poor this year, so I'll need a strong application next time to stand a chance of being chosen for the champs again.
    I'm still thinking about it though. In the meantime I will continue doing a CAD for "Strix 2".
    Last edited by dotDominic; 18th September 2018 at 11:05.

  10. #70
    fair enough but I would suggest trying to reuse bits e.g. the hardox

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