Pendulum - FW Beater

[Andy]

Hey all

Since Insomnia was this week, I thought it would be a good time to make a build log for Pendulum and document the build up until now.

I started designing the robot late 2014 and was using SolidWorks at the time because I got it free from college. Went through a lot of design changes until I was pretty sure I wanted a 4 wheel drive drum spinner after being inspired by Attrition and Unmakerbot in the US.

As the 2015 GSL event was nearing I decided to ditch the drum as it was going to cost a lot and take quite a bit of time to manufacture, so went for a beater instead, which while having some downsides in chassis strength and aerodynamics, has more weight on the outside of the weapon which means hitting harder.

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I picked up a 20mm thick Toolox 44 plate and dropped it off to be water cut, this is how the blank came out before being further machined.

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Harry Hills kindly helped with this on his lathe, turning the ends to spin in bearings as well as facing the sides on his mill. Came out brilliantly just like the other bits and pieces of machining hes done on the robot.

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Few pics of the robot, probably March/April 2015. As you can see it is insanely compact, a design flaw that I'll try my best to avoid in future. Since these pictures were taken some of the internals have been changed for smaller parts, including 550 motors rather than 775 motors on the drive and smaller ESCs.

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Due to time constraints and a few mistakes I made in the CAD stages, I didn’t get the machine ready for 2015 GSL, I can’t fully remember what went wrong but it was mostly to do with belt lengths and just not having enough time left to correct the design errors.

Got new bulkheads made because I really wasn't happy with the original pair, as well as a few other things improved throughout the year to get it ready for 2016 GSL which I don’t really have any pictures of, but here is the finished robot and the first proper spin up test!



The robot had a few problems at the event but overall the weapon worked reliably and I managed to get to the quarter finals.

Improvements for Insomnia..

I realised the robot was bouncing back after hitting opponents was partly due to the ground clearance of the weapon and also because the wheels were most likely compressing due to the impact as the robot had no proper front “feet”. I added new front wheels which are solid nylon, in the hope that they wouldn’t compress at all, and will act as feet, putting more energy from the weapon into the opponent on impacts. Also made some front wedgelets to use against pretty much anything but other spinners. Since the robot was only 10.7kg at GSL I also had a Hardox base cut, to strengthen the chassis slightly and add more weight to the back of the robot to add traction to the back wheels and make it more likely to drive properly upside down.

Was very pleased with the additions to the robot improving the performance of the machine a lot, the front wheels and wedgelets both working how I wanted them to. It was a brilliant event and as always I had a fantastic time!

My first fight of the competition was against Tormenta 3, I wasn’t very confident the robot would work too well at this point because of having to trouble shoot a fair few problems on the testing day. Going into this I was expecting the wedgelets to not have anywhere near enough weight to get under the wedge of T3 and to be bouncing around most of the fight, I was pleasantly surprised when the wedgelets get under him at the front, probably the folded parts of his wedge, so I could hit him once and then get a second hit in, winning via OOTA.



Second fight of the first day was against Explosion, I knew this wasn’t going to be an easy fight to win but hoped using the wedgelets and keeping my weapon to him I’d have a chance, turns out I didn’t!



Had a "friendly" whiteboard with Flatpack on the first day too where the wedges went under the sides of his wedge, similar to T3 (I think) and sheared some of his front bolts and knocked the link out, was pretty shocked at the result but sadly don't have any footage of the fight.

Third competition fight was against Drumroll, was pretty nervous for this one and expected to come out with a fair amount of damage, there was a big collision at the start of the fight which if I remember correctly, bent drumrolls weapon shaft, stopping his weapon. I carried on chasing him for quite a while, but had electrical problems, the BECs of the two drive ESCs killing the receiver and doing very weird things, so the robot died, big thanks to Ed Wallace for letting me borrow his receiver for the rest of the event and also Ellis and his dad for letting me use some of their equipment to try and solve the problem.



Fight four, I won’t go into detail here but it was Explosion for a second time, I turned the robot on and the weapon ESC was in settings mode, Michael managed to take a surprising win!

Fifth fight, Loki 2, hoped the robot would work again after replacing the weapon esc and changing out the weapon belt making it sound a lot smoother, turned on the robot about 20 minutes before the fight to check it worked and it was completely dead. Had to delay the fight and open it up and found that the fuse had broken, very odd since it was fine the day before when testing the weapon but just glad I checked haha, after a bit of maneuvering I flipped him over and his link broke.



Fight six was against Onyx, very fun fight since Jamie let me carry on hitting him in an attempt to retire the robot!



The damage to Onyx after the fight..

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Had a whiteboard next which I don’t have video of against Ironside 2, Hardwired 3 and Omega. The fight was a bit of a blur but took/gave out a few hits to both spinners, taking a few chunks to the beater and the outer armour. In a head on hit to/from Hardwired 3 I managed to shear the bolts holding one of his discs to his weapon hub which I was surprised about.

Second whiteboard that day was against Tormenta 3 (again) and Mutiny; I removed the wedgelets for this fight to make it last a bit longer than my first fight against Ellis at the event. It was a brilliant tussle between all three robots and probably my favourite fight with the robot to date. The fight almost went the full three minutes but managed to remove Tormenta’s wedge, Ellis reckoned it was a lot of different hits removing the bolt heads on his wedge rather than one big hit. I also did some damage to a side panel of Mutiny which I hope will be fairly cheap and easy for the team to repair, the robot was very well driven through the whole event.



Some pictures of the damage to T3 and also a shot of the wedge stuck in the roof lol

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Pendulum as it currently stands..

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Overall I finished the competition with three wins and three losses, loved the new format and being able to get lots more arena time over the event Not much to change on the robot for the next event, I want to improve the wedgelets in strength as one of them ripped out the front of the robot and bent all the bolts mounting it after the robot landing on it from being flipped by Explosion, I’d also like to make thicker and potentially longer forks to get under more people. I’m going to have a good go at rewiring some of the robot to make it tidier and easier to service too.

That's all for now, cheers!

[ChrisKazoo]

Pendulum worked great last weekend, and getting T3's wedge stuck in the lights was one of the best moments of the event!

[PredictedCyborg]

I wondered what had sheared off all those bolts on Tormenta. I missed a good number of the fights at i58.

[R9000]

I wondered what had sheared off all those bolts on Tormenta. I missed a good number of the fights at i58.

I wasn't there, but I'd assume it was Pendulum's beater.

[Andy]

Thanks for the comments guys, I'll probably start on upgrades and such for the next event fairly soon..

In the mean time here are some pictures of the wheels and how I fixed them for this event. At GSL I used 3D printed pulleys and keyways on the back wheels and a few sheared from impacts so as well as changing the front wheels I needed a new, tougher way to fix the back wheels to the motor shafts.

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An m4 bolt goes through each wheel, had no problems at all with this easy and simple method.. Also changed to better quality belts without the need for tensioners on the drive

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Cheers

P.S. Nick, the format was a league system, so everyone had 6 fights over the three days and the ones with the most points went into a final fight and playoff, there was also no judges, if both robots were both running at the end of the fight it was called a draw, and both robots got 2 points.

[overkill]

Excellent report - beating Tormenta is a difficult thing to do! What is the 'new format'? Maybe I missed the official description, but there doesn't seem to be any details on-line.

[Upstart]

Cool bot! Which bearings did you use for the weapon?

[Andy]

It uses needle roller bearings but one of them shattered after a massive impact with Mr Mangle at the champs earlier this year so I wouldn't recommend them on a spinning weapon. I have some bushings as back up now, but if I had the room id use some big roller bearings.

[Giles]

I was impressed with Pendulum at Insomnia, seemed to be performing really well! I think the wedglets were the biggest improvement, so if you can find a way to make those more robust it would be really nasty.

[stef]

I really like the alumiunium sides that are machined out of one solid piece

stef