Peter Wallers Robot Ramblings

[razerdave]

Trying to name them all..and failed
Variant
Combatant x 2
Flippant 1 and 2
Defiant
Antrax (I think)
Millitant
Mutant
Dominant x 2
Deflea
Fleabyte
and 2 I don't know the names of

[peterwaller]

Thats well remembered the two servo flipper drive all day never really had names, the DAD with pincers was antrax in a previous existance but when I removed the tracks I renamed it Pincer. The thing with just tracks was something I knocked up for the obsticle course at Richmond again has no name.
All the rest I think you covered.

[peterwaller]

I was out in the garage etching a PCB this morning and came across another old Combatant and NotsoFlippant.
They have had their batteries and receivers unplugged but otherwise complete.

[haz]

haha, it's probably a bad sign if you can lose robots
that's my favorite version of combatant

[Remote-Controlled Dave]

Peter, you should enter a retro AWS team one time. All the old versions, just to see how they do. Could be like when you entered Defiant after so long and it ended up winning.

[peterwaller]

After changing the wheels on Fleabite to improve the grip and finding I had virtually none (quick change back during AWS) I decided it was time I had some way of measuring the grip / traction of various wheel / tyre combinations.
This is what I came up with.

The chassis has two bigger than standard motors and weighs in at 144 gms.
The two pieces of angle keep the chassis straight and pushing at right angles.
Here is the first push showing about 170 gms.
http://youtu.be/DfkwXrzsk9w
Adding double width wheels with the same tyre material reduced it to 150 gms.
What is really strange is that the wheels in the picture were the ones I had fitted to Fleabite that skated around all over the place.
I have just put the narrow Pololu wheels which greatly improved Fleabite onto the test rig and only get about 120 gms.
So it is beginning to look as though traction under vibration conditions can be very different to that under normal conditions.

[Andrew_Hibberd]

I like the set up, it would be nice to plot a graph of wheel width against pushing force for various materials. Although impractical with the ammount of time it would take to make them.

It is interesting that the old wheels felt better to drive but the new ones gave more push. The only thing i could suggest is making a lighter bot (75g) to simulate a flea, and see if the pushing force is better in the old wheels.

Over thinking this, there could be something dynamically happening with more wheel speed slip giving less grip. You could try more rpms to see if you get more from the old wheels.

I am interested to see what results you get, as grip is huge part of the bots.

[peterwaller]

I have now tested a few of the wheel / tyres I have laying around and have added the results to my website with the motor table.
http://www.antweightwars.co.uk/TyreTraction.pdf
So far the best seems to be the sticky lint roller with the HP paper rollers a close 2nd.

[EpicentrE]

Really interesting results so far Pete, thanks for doing all this testing. I'm very interested to see how the egrips perform when they arrive.

[Andrew_Hibberd]

I have put together my own set up and have sucessfuly cast some polyurethane wheels. I have been using the top of my desk, laminated chipboard. The results on 7.4V with 30:1HP motors is as below:

225g very old lint roller 20mm diameter 25mm wide- very bouncy movement (in the robot these were very slippery on the drive)
170g fingertech wheels 29mm diameter 20mm wide - no bounce
125g 18mm wide 19mm diameter slot car tyres - no bounce at all (same type as in nom nom nom which give very good control)
115g 29mm diameter 20mm wide shore A50 home made wheels (very bouncy)

What it looks like to me is that the bouncy wheels are too grippy and the up down movement of the bounce give them more push, but will be slippery to drive in a fight. I think the perfect pushing wheel should not bounce in this test. I will have to try out the fingertech wheels in a robot soon. Also the new home made ones are very tacky atm, I will run them arround a bit and see how well they do with a bit of dust on them.

Pete did the cricket bat and printer rollers start to bounce with faster speeds?