Team Saint Robot Builds

**epicentre** · 6th May 2015, 22:19

Why mecanum wheels? I would've thought either a 3-motor setup with 3 omni wheels, or a 2-motor setup with 2 omni wheels each, would be much more suitable for this sort of thing. I'm not sure mecanum wheels will work properly, if at all, on a non-flat surface, and I'd certainly expect the movement to be less smooth than with omni wheels.

**craig_colliass** · 7th May 2015, 09:11

Hi Scott

The best part about this project is I have not done anything like this before, and I don't know what will work.
After receiving the wheels I am thinking the same thing, and I might go for the 3 wheel setup. later
The sphere
I am still finding no useful balls for the main body, will keep looking. any possible leads welcome. (500mm diameter split-able and plastic)

With regard to Gabriel
I have turned my attention to the Torque limiters on the drive wheels.

IMG_1082.jpg

Because of the damage done to the transmission by flippers flipping the wheels. I am now making torque limiters in the hub centres.
the Idea is to let the wheels spin on the hub when too much force is back driven into them, the first attempt to do this has been quite successful.

**harry hills** · 7th May 2015, 16:07

I think 3 motors 3 wheels would be better. You'll have 3 point contact (think like a 3 legged stool) which to my mind works a lot better.

But as you say, its all an experience. I really hope you have a lot of fun with this one!

**RogueTwoRobots** · 7th May 2015, 20:07

Hope you don't mind me sharing this here Craig, it's part 2 of the BB-8 build that someone is doing on Youtube. I posted part 1 earlier. He's doing it slightly differently from yourself (due to him building it before the SW convention appearance of the physical droid) but it's fascinating and enjoyable watching nonetheless and thought it may be of general interest.

The 12-minute mark is where it's self balancing on both axes.

**craig_colliass** · 9th May 2015, 08:27

Finished the links for Gabriel one shown here. the back plate with the pull tab is about 5mm Polycarbonate

IMG_1088.jpg

The fuse format shown below should fit this type of link too, and is rated at 150A just in case the 100A fuse fitted dose blow under normal conditions.

BTW has anyone else used 2 Roboteq AX2550 (as single channel controllers) in one robot before?

**craig_colliass** · 10th May 2015, 19:10

Hi I'm looking for a gismo that can be connected to speed controllers that drive fan motors. the idea is balance
imagine a horizontal board that can pivot in the centre, with 4 fans fitted front back left and right, if the board is pushed down at the front the front fan will run to raise the front, and the rear fan would run to push down the rear until the horizontal plane is maintained then the fans stop.
I'm thinking the multi rotor units must have something like this on board, any ideas?

**grant_ploughbot** · 10th May 2015, 22:31

Most general multirotor controllers should do somewhere close to what you want - the difficulty will be finding one that will work with the fans stopped. Normally they need to be activated and start the props spinning slowly to work.
A potentially simpler way may be to use a standard gyro with the output to the fans?