Peter Wallers Robot Ramblings

[Rapidrory]

I found that using the scoop as a flipper on bully was not nearly as effective as using it as a controlled lifter... but then again you do have a pink servo in there so probably have a bit more power for flipping :L

[peterwaller]

I find the same on flippant, although capable of a reasonable flip most robots can easily recover quickly, so I find a lift and sometime if I am lucky a carry to the edge works better.

[peterwaller]

Finally getting round to setting up a practice arena so I can try and improve my driving skills on a moving target.
Basically it is a white arena with a black circle in the center the size of a mini sumo arena.
I have stripped some of the weight off one of my mini sumo robots LowBlow and given it better tyres which should run around in the black circle looking for a robot but turning back at the edge.
I can then drive my ants into and out off the circle trying to avoid detection and practicing my driving.
Just waiting for the paint to dry at the moment I will let you know if it works.

[peterwaller]

The arena seems to work quite well.
This is the slowest of my minisumo's and as you can see I can get out of range of the detectors with the faster ant even when still inside the circle.
I haven't put any mylar on the front of the ant so I have to try and avoid head to head encounters or get pushed out.
https://youtu.be/XJTZU1ZqDbA

[peterwaller]

Just been trying to improve the tracks on the new Defiant.
The soft molded rubber gives lots of grip but the tracks are very stretchy and so tend to come off in turns.
I have been considering molding some kind of insert into the track but t still needs to be a bit stretchy to be able to put the tracks on and elastic bands or indeed any latex rubber prevents the rubber from curing properly.
Hence as I mentioned elsewhere in the forum I decided to try printing some in Filaflex rubbery material.
My first attempts ended in failure with 20 cm of the filament rapped round the extruder drive wheels.
After a quick visit to my favorite 3D shop I found out you have to turn off the filament retraction, slow down the print speed and print straight on to glass.
This has resulted in some very credible inserts one of which is in the mold right now.
The insert is basically a band 4mm wide and 1mm thick with 4 bulges on the inside to hold it central in the mold horizontally and 4 legs on the edge to position it centrally in the vertical plane.

Turning off the filament retraction means you get fine stringy wisps left when the head moves from one part to another but these can be easily snipped off afterwards.

[peterwaller]

The inserts worked brilliantly ending up right in the middle of the molded track.
Unfortunately in an earlier attempt to get the tracks to stay on I had increased the distance between motor centers by about 10 mm to increase the tension so the new ones are a bit on the tight side.
They do in fact stretch enough to go on and they do run but they are so tight the tracks are bulging out either side if the drive wheel.
Looks like its back to the drawing board but at least it works in principle.

[Rapidrory]

Looking good pete!

Was wondering whether you could maybe use timing belts as track inserts. apparently they're relatively stretchy when they're fairly small cheap ones, and have have plenty of teeth for the silicon to grip onto... Something like this maybe? http://www.ebay.co.uk/itm/4-3mm-Thickne ... SwyQtVwry6

[peterwaller]

It would certainly be a possibility assuming the rubber in them is not latex based but now I can print them I can make them any size I like.
Hopefully the right size eventually.
At the moment I am just printing a new mold to give me track 14 mm longer so it only has to stretch 3 mm instead of 10 mm.

[peterwaller]

The longer tracks fitted much better and work well.
I have even tried a couple in the even softer rubber but due to the extra grip and flexibility they show signs of trying to twist and eventually come off in continuous spins.
I think I could probably fix that by making the insert 8 mm wide as opposed to the present 4 mm but I am not sure it would be worth it..

[peterwaller]

Having tried the new tracks on a chassis without any track guides I found the new tracks could still come off in continuous turns.
So I have made some in the firmer 10 A rubber with the 8 mm wide printed insert and they stay nicely in place.
Here they are on a newer modified version of Defiant where I have moved the scoop forward and cut away the front to hopefully improve its marble handling ability for the weekend.