Help with choosing parts for a first robot, please.

[dotDominic]

IT WORKS! VENATOR ACTUALLY WORKS!! THERE'S AN ACTUAL FIGHTING ROBOT DRIVING AROUND IN MY BACK GARDEN HOW COOL IS THIS

I'm so delighted with the result: Started with no experience in this sort of thing and a couple of rusty old tools. 18 months later I've gained a basic idea of Electronics, D.I.Y. and CAD Modelling, as well as a real fighting robot!!! Obviously I still have lots to learn but I have really enjoyed the build process. Just got to put on the steel wedges and it's good to go!

So a massive thank you to everyone who has posted on this thread and helped me out over the past year and a half! Considering the number of mistakes I've made, I would've never been able to do this without your advice.

Now I can actually fighting this thing! Will probably get smashed to bits but can't wait!

(Also, at the moment my DX6i has mapped the controls on a sort of diagonal, if that makes sense. So forward is top right and back is bottom left. Any idea how I can fix this? Thanks.)

[R9000]

Dude, this is so cool. It certainly looks pretty rigid, and it should hold up well with some steel wedges. I'm not sure how to fix the DX6i problem, but I assume it has something to do with channel mixing. I hope it gets on well in whatever first event you take it to, my chassis and drive system is almost done, so maybe we'll see each other at one of them.

[RogueTwoRobots]

IT WORKS! VENATOR ACTUALLY WORKS!! THERE'S AN ACTUAL FIGHTING ROBOT DRIVING AROUND IN MY BACK GARDEN HOW COOL IS THIS

(Also, at the moment my DX6i has mapped the controls on a sort of diagonal, if that makes sense. So forward is top right and back is bottom left. Any idea how I can fix this? Thanks.)

Congrats, glad to see the wiring mix-up didn't damage the ESCs and you've managed to get it working
The next toughest stage of robotics is learning how to drive and video it at the same time while being able to keep the camera pointed at the robot :P

With regards to the transmitter controls, it sounds like there isn't any form of mixing currently set up on it, so one channel is linked to one side of drive, and the second channel to the other (so fwd/back will move one side of the robot only). I'm not well versed in the menu options of the DX6i as I use Futaba transmitters, but if you look for a mixing menu, there should be an option for Elevon mixing, which should give proper joystick control with forward/back/left/right all matching with the stick movements.

You may find, when you turn mixing on, that moving the stick forward and back makes the robot turn left and right (and vice versa with the left/right stick). All you need to do is either swap round the ESC plugs in the receiver, reverse one or both channels, or swap terminals round on the motor connections. Just a case of trial and error with this; do one option at a time and see if it achieves the desired result, then keep going until you've got it all set up correctly.

Hope that doesn't sound too much like gibberish :P

[leorcc]

Jamie is correct.

Below you can seen how to set up Elevon with full throws on a DX6i.
http://www.youtube.com/watch?v=6Ewa79_9Iq4

[dotDominic]

Haha, thanks! Yes my driving definitely needs practice. Hope your build is going well Rory!

Ok - I think I've pretty much got mixing down now. Although foward/back is working great, turning/spinning is only left/right on the stick rather than top left/top right etc. Instead the corners just make the bot go forward/back. So I can't turn as fast as I did in the video. Is it meant to be like this? Will have a fiddle with the settings to see if I can sort that. Also, when it does drive forward from a standstill, it sorta turns slightly beforehand, so actually driving in a straight line is quite tricky - is that just the nature of controlling something like this or can it be fine tuned with the transmitter? Or has it got something to do with using custom wheels which naturally won't have the brass inserts dead central?
Thanks,

[typhoon_driver]

Not sure I understand what you mean by top right and top left on the transmitter when it comes to control.

In answer to your question about the turn before it sets off, you need to set up the trims on the transmitter. If you look directly below and to the side of the sticks there should be a little button or slider that allows you to set the trim (or bias) on that channel. It takes a little work experimenting to get it all set up well.

[dotDominic]

Cool thanks, will try that out later on.

Probably easier if I explain this with a picture:
Transmitter stick position.png
I thought that if I move the stick to where the red mark is the robot is supposed to spin? Right now the robot still goes forward in this position, and only moving the stick horizontally right and left makes it spin on the spot quite slowly. Unless it's meant to be like that, feel free to correct me. :P

[typhoon_driver]

sounds like it's working as it should do. Left and right on the stick will cause the bot to rotate on the spot. Up and down on the stick will allow the bot to go back and forward. Putting the stick in the position you highlighted will make it go in an arc to the right.

Personally I go for two stick control (forward back on the right stick and left and right on the left stick) but that's just personal preference.

[R9000]

Cool thanks, will try that out later on.

Probably easier if I explain this with a picture:
[ATTACH=CONFIG]5981[/ATTACH]
I thought that if I move the stick to where the red mark is the robot is supposed to spin? Right now the robot still goes forward in this position, and only moving the stick horizontally right and left makes it spin on the spot quite slowly. Unless it's meant to be like that, feel free to correct me. :P

It should certainly spin at a decent speed with the motors you've got in there. I second what Gary's saying, the robot certainly shouldn't go straight forward when the stick is in the position above, it should arc to the right.

[dotDominic]

Ok thanks. Perhaps it is actually arcing to the right/left, but my testing area is so small at the moment I haven't noticed. That sounds like an interesting way of controlling it - I will try that out too then.