Team Death - New Heavyweight

[Maxamuslead]

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

[team death]

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

[Ocracoke]

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).

[Redirect Left]

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

[team death]

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.

[RogueTwoRobots]

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.

[Redirect Left]

[..]

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

[Theo]

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.

[team death]

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

[Redirect Left]

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.

[Redirect Left]

Sundaaaay!

This week we tried something a little different, a skid! Colin had preprepared this during the so its week, and the only thing left for today was to weld it in place, which we dutifully did. We used polycarb for the base of the skid, as it was the item of least friction there was to hand around the workshop.
After welding, we got straight off to the testing area. The skid correcfted the steering issues, and the bot drove in a straight line. However, the motors were notably making much more effort and current draw, and whilst it worked OK in forward and reverse, it struggled to turn corners due to the added friction. When checking on the bot, the connectors were noticably hot from the battery, where they are usually nothing more than lukewarm, so the motors must have been trying considerably harder to make the machine move, if there is enough current to make them hot. In the end, we removed the skid, but we still have it if we decide to use that later on. We're going to reconfigure the castor layout instead, and try to get the same straight drive, without the extra friction the skid was causing. Unfortunately we can only test on concrete, so the friction may have been OK in arenas, whose to know.
The skid;
IMG_20180520_140449.jpg
Next week, we'll be doing the castor change, and going out to the test area again - we may revisit the skid perhaps with some nylon instead of polycarb.

I had also acquired some bike tyres over the week, and one of the plans is to cover some tyres to try increasing friction. We tried this, however decided to try other things, as it was taking way too long to even do one piece. We may revisit this if we decide this is still the best couse of action later on.
Here is an image of that, this is a pneumatic (air filled) tyre, with the internal air hose removed, and the donor tyre riveted on. We went with rivets, as it's the method that we hope will leave the least amount of debris inside the tyre for the air tube to burst upon. It also looks rather industrial from the outside, which fits in withthe overall theme. There was also a layer of glue/cement suitable for rubber underneath, although we later found this had not stuck at all, and was only being held on by the four rivets.
IMG_20180520_130024.jpgIMG_20180520_140726.jpg

This is a very time consuming thing, especially as the rivets take a lot of might to pull together, and each piece takes 4 rivets, and the tyre will take 9 pieces of tyre. However, I think next week we'll go straight to the castors and see if we can make that work before revisiting any of the above.

[team death]

After the semi successful trial with the skid on front of the Robot
I have concluded that if it is used in combination with castors it
might just solve our steering problems.
A built up front spike is needed anyway to feed the enemy into the scoop
as at the moment the scoop rides an inch or so above the surface
Also I just received from e bay a new pair of bearings for the wheels
which I intend to make adjustable and thus make both wheels touch
the floor evenly -this should also help with the steering if I can achieve
the same level on either side

[team death]

Sunny Sunday -Today I mainly worked on the front skids of the Robot
and I'm hoping that balancing the front end weight between the scoop
and the castors will greatly improve the steering of the Robot.
Unfortunately Adam was unavailable this week so I was unable to take
the Bot for a test run-it really is a 2 person job to cart around.

Last week we tried the Robot with 65% of the weight on the front MK1
skid, this had the effect of helping with straight steering but the Robot
had to work too hard and leads got hot -also the turning was quite poor.
Before we fitted the jaws the steering was really quite good so if we can
negate the weight of the jaws by putting 12kg or so on to the scoop skid
the motors should be less strained and the turning and steering should be
better.
Adam had been chatting with the crackers and smash team a couple of weeks
ago and they suggested we changed our battery holding sleeves because any
impact would be transferred through to the batteries, so today I also removed
the sleeves and we will probably wrap the batteries in foam or bubble wrap.

Because I wasn't pushed for time today I visited the car boot sale in the morning
and picked up some interesting items including two game console remotes which
we can adapt to use for the weapon,a small car that I may make into a ant or beetle
weight and a broken helicopter full of servos motors and cogs.

[Redirect Left]

Today was a bit of an odd day.

We have started by getting the skid setup ready. There was a spring handily around the workshop, which was cut in half, then a little more - and sprung around both of the bolts to give a little suspension effect to the skid, so it'll hopefully bounce about a bit and maintain a constant pressure on the floor and aid in the straight driving.

Whilst the other battery charged, we worked on a different encasing for the batteries, mostly using foam. We had to shave a little off one of the bolts for the castors, as we were a little short of space on one side. We're now in a position where the batteries will comfortably sit one at each side, as they were before. Just in a manner that is going to be a little less drastic for them in situation where the chassis is badly hit and shaken about.

This passed enough time that now both batteries were charged, so we went out for a test. Which very rapidly went doooown hill. Almost immediately, I was able to drive it straight after a try or two with it skidding off to one side. It didn't take me long to find the required direction on the controller, just ever so slightly to the right, to achieve a straight line. If we cannot get it to naturally drive true, then this is something that won't take long for either myself or Colin (driver is still to be determined!) to adjust to, as we are running out of time and there are a few other things to do, such as the weapon and remote control of it - so we may have to leave the driving as is, at least for its first battle and we can come back to it again later on if needs be.
Unfortunately, this is where the test abruptly ended, as we again came across a rather huge setback that was irrepairable out in the field. We had another weld failure, so we packed back up and headed back to the workshop.
It took us a while to find out exactly where the weld had failed. But sure enough, the smaller sprocket had become unattached to the main bar. A little animation is the best way to describe it;


This proved a little odd to fix. Colin welded the end of it together - this is the end that goes into the bearing, and also added a little delicately between the two sprockets, bearing in mind that once the chain is running, there really is very little space remaining to ensure smooth running of the chains.

Whilst Colin did the welds - as im clueless on that side! - I discharged the batteries using a spare motor, as we thought this'd be quicker than using the charger to discharge it. As it turns out, no. These motors seem to use really little current when they're not loaded! Batteries discharged by a whopping 0.125V each in the space of 5-10 minutes. Compared to what would have been going on for a full discharge in the actual machine and its two motors.
Here i am, fruitlessly trying to discharge the batteries.
IMG_20180603_151915.jpg

Next week, I am unavailable again, due to attending a tournament at Wembley Arena (not the big stadium!) for a game. But I believe Colin will be working to put the drive together again, and try to make sure we're going to be high and dry welding wise this time around, so we can go straight to the weapon onwards hopefully. Whilst the mechanics are all there, and we believe it to be functioning if untested with the full setup, it's currently got no control mechanism for it. So we need to wire that up, add a receiver to it, and wire up a seperate panel to the controller for whomever ends up controlling it seperate to the driver. Unfortunately, the robot is currently way too heavy for a single person to carry around, so i'm not sure how much testing Colin can reasonably do next week. However this evening, he was off to pickup a trolley he got on eBay cheaper than new, so that'll ease the task somewhat. There is also a further plan to try easing the driving issues, depending on if we can get the parts at a suitable price point - more on that next week, when we know the outcome!

[team death]

As a follow up to Adams post -the chains on this side of the reducer sprocket have
always been very close together, almost to the point that they may have meshed
together at some point and this may have attributed to the weld failure.
After welding the reducer yesterday I made the mistake of making the chain
sprockets even closer and thus the chains are now touching even worse.

So I will have to dismantle it again and next time get the chain
distances as good as possible.

Adam asked yesterday if it was just as well to start a fresh but I know
how long it took to make on the lathe and welding the sprockets on near
true-about a full day each-so that will be the last resort really.

Last night I traveled north of scotch corner to pick up the hydraulic platform
to make life easier when we take the robot to live events-its rated at 250kg
so that is plenty strong enough for our 110kg Robot and it has a wide and
long table to easily big enough to hold the bot safely.