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Thread: Team Death - New Heavyweight

  1. #151
    Maxamuslead's Avatar
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    if you got a halfords near you see if you can acquire a load of old bike tyre as that work great, really saved my butt at manchester

  2. #152
    Apart from the batteries running down rather quickly and the wheel spin...
    I noticed when driving the Robot I had to keep adding a little more power
    to the left hand side of the Bot (as viewed from the rear) via the controller
    ie :slightly turning right to keep the Robot on a straight track.
    The gearing for the motors is identical and so are the motors and wheels,
    I'm thinking the right hand side of the Robot could be getting a little bit more
    traction than the left side- retro fitting bike tyres or similar could resolve this, so
    it might be better to remedy this before altering any trim on the controller.

    We may turn our attention to the weapon this weekend while we ponder
    the best way to improve the traction and battery longivity

  3. #153
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    Team Kaizen

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    The other thing you could do is adjust the trims a little, I found I had to do this on my featherweight as it had a tendency to veer off when going straight (again, same motors, same gearboxes etc).
    Team Kaizen

    AW: Osu, Ikari, Ramu
    BW: Shu! (Build Thread)
    FW: The Honey Badger (Build Thread)
    MW: Kaizen (Build Thread)

  4. #154
    Redirect Left's Avatar
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    I've just remembered, i have a spare transmitter and receiver pair here at my flat. I could bring that along on Sunday, and quickerr replace the receiver in the bot and see if it has the same drive issues. If it does, it would point to either something in the ESC, a motor behaving not quite identically as the other, or a few other things. But it'd certainly eliminate the transmitter/receiver if this works fine - and we'll have a pinpoint to help wittle down the issues in those two if we need to stick to the transmitter/receiver pair we originally used.

    The one I have is a fairly basic one, buts it has six channels - it was only ever intended for featherweight and below stuff i was doing at home at the time - https://www.ebay.co.uk/itm/381958044606

  5. #155
    Thats great Adam-bring it along and we might be able to determine if the steering
    problem is in the radio signal or like I suspect one wheel getting more traction than
    the other.

  6. #156
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    Jamie McHarg
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    Colin notes that the drive is still a little off. Driving in a straight line is still quite hard to achieve. As hes been doing all the driving during the testing phase, I'll leave him to note down the specifics in a post soon after this, and hopefully someone can aid us in that area too.
    The main issues I see are the castors and the wheels. The wheels are very large, close together and right at the rear of the robot. The robot is also quite long and thin. When large wheels are as close together as they are here, it's always going to be difficult to get the robot to go in a straight line; it's much more likely to have a tendency to veer off to one side (which side will come down to the dragging issue Colin mentioned) compared to a robot that has a wider wheelbase. Having a lot of the robot's weight towards the front of the machine and less over the wheels also means that it can possibly pull to one side depending on weight distribution etc.

    The issue with the castors is that they reduce the rolling friction of the robot. In principle this seems good as the motors will technically have an easier job, but it does mean that when the powered wheels stop turning, especially when turning/spinning, the momentum built up will continue to rotate the robot, giving an oversteer effect. Most robots these days do away with castors and run with their leading edge just scraping along the floor. This dampens the driving and associated effects such as veering and oversteering. It means the motors will be drawing more current to move the robot, but I doubt the difference will be significant.

    Obviously there's nothing to be done about the wheel width, it's pretty much set in place. You could try experimenting without castors if the robot's leading edge wouldn't hinder this (or try replacing castors with skid plates made of, say, Nylon) and see if that improves matters. The other option to consider would be the use of a gyro, which monitors the robot's movement along a certain axis and corrects any deviations. Never used a gyro before personally, but they can be a bit finicky to set up and use correctly, so you may not want to consider that option yet.

    Either way, good to see the end is in sight. It's looking very grungy and agricultural, look forward to seeing it in an arena.

  7. #157
    Redirect Left's Avatar
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    Quote Originally Posted by RogueTwoRobots View Post
    [..]
    Thanks for your input. We may try that next week. The castors aren't too hard to get on and off for quick testing without, so we should be able to do a before and after on that relatively quickly. 'Grungy and agricultural' has ended up looking quite good, and its definitely going to be painted in a manner that keeps it looking that way, when it comes to the final steps and paint jobs!

    Today we had another build day, although it was mostly testing and talking.
    We got to work charging the batteries, although we knew the testing today was going to be brief so we didn't go for a full charge.

    After chatting and having a bit of a laugh for an hour whilst they charged, we went up to the testing place, this time with the receiver and transmitter I had brought up from Wakey. The drive seemed a little better, but not perfect still. It was my first drive, so I couldn't really determine the difference, however when Colin tried he said it was running a little better. So perhaps the trims are off on the other transmitter - it's also possible it may be a technical fault, as its a second hand controller, whereas mine is a new one.
    As noted, the drive is still a little off - however it is now at a point where it can be adjusted on the fly with quick fingers to bring it into alignment. Next week, we're going to try to see if there is a reason why one wheel is getting more friction than the other, perhaps the build is slightly off angle, we'll also try it without castors - as we'd already considered that. Although unfortunately we don't have a nice surface to run on, so we'll be all scratched up if we test it without castors and it runs on the floor too much.
    At some point, we'll need to decide what transmitter/receiver to use.

    Today was my first go at driving it, and I have to say. I'm surprised at how nippy it can be, due to the placement of the two wheels, it can turn rather quickly, to the point where you'd certainly not want to get in the way when its turning at max throttle, it really throws the front end around in a spin - may end up being a useful tool in a fight!

    As a sidenote, today we discussed a few potential things to do after the HW was completed - and I think if we do get to do them, a lot of people may be pleasantly surprised by what we may have up our sleeves! We've also discussed what

    During the week, Colin is going to try re-assembling the jaws ready to test that next Sunday. So hopefully by the end of next week, we'll be a step closer to battle ready - all we need is an event not too far away to run it!

    The bot in the sun, just before testing. Was fabulous weather for it!
    F_iPPjMQrF.jpg

  8. #158
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    I think one wheel's slightly higher off the ground, you may want to check the shaft it's on. I'd test it first without the castors and work from there. Apologies if this is in a massive font, first time posting from a Blackberry.

  9. #159
    Ups and downs on the Robot build this weekend-Yesterday I charged the batteries
    to full capacity for a good test run today, I also re-fitted the jaws to see how
    the Robot handled with them in place.
    Adam arrived at 12 today as usual and we put them speed controller back in
    the Robot and set off for the test drive area.
    Adam had brought with him some battery monitoring devices so we fitted
    them before we began to drive.
    Almost straight away the Robot felt wrong, not helped by the fact we had wired
    the speed controller motor connections the wrong way round.
    It turned out the weld had broke on the reducer sprocket so we had to make a
    quick retreat back to the workshop to weld it.
    Upon our return we had a little more luck and got the Robot to drive with the
    jaws in place for the first time, the skewing of the steering was slightly worse
    than last week and I thought it would be because of the extra weight at the
    front and we are still using the castors for the moment which we may change
    to a skid.
    Unfortunately after a couple of minutes a bungee strap we had been using to
    hold down the the e E S C got wrapped round the wheel and one chain came off.

    Apart from the niggling problems we are both pleased with the Robot and we
    can finally reveal the Robots name...........


    THE
    MEAN
    MACHINE


  10. #160
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    I've got the images from today;

    Today is the first time we've had the jaws in, with the additional ESC box on top. So this is the current overall look of the machine, there may be a few changes, mostly to the wheel areas, but I think this is near to the final look of it all, minus the final paintjob to do at the end - which will maintain the red/black theme.
    IMG_20180513_131238.jpg
    This is from the first thing to go wrong. Shortly after arriving to start with, the welding joint on one of the smaller sprockets went. It's worth noting, that this is probably due to us forgetting to redo some of the original temporary welds. We've now gone above and beyond what they originallly designed to do, and we're getting these issues. It's much better for them to show up now, than at an event.
    IMG_20180513_140049.jpg
    One of the first signs of going wrong on the second trip. This is the bungee cord to secure the ESC in place in its temporary testing place - as it isn't secured in there by anything other than the wires. Unfortunately we forgot to secure the securing bungee, and it quickly ended up tangled and shredded, probably due to it coming into contact with some of the sprockets and chain? Whatever precisely occured inside, a chain was found to have come off when we got the bungee out.
    IMG_20180513_145858.jpg

    Next week, we've already got a to-do list from todays events. We're going to have a go at the wheels next week to resolve a few further issues, although exactly what that'll entail and end up being, is unknown until we come to do it.
    Last edited by Redirect Left; 13th May 2018 at 19:56.

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