Team Death - New Heavyweight

**RogueTwoRobots** · 6th May 2018, 00:27

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.

6th May 2018, 18:05

Originally Posted by RogueTwoRobots

[..]

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

Thread: Team Death - New Heavyweight

Thread Tools

Search Thread

Display

Hybrid View

Tags for this Thread

Bookmarks

Bookmarks

Posting Permissions

Site Map

Event Organisers