[chbot] Hexapod....

[Chris Hellyar]

Hi-ho...

After a couple of fun evenings with the #1 son assembling the kit..

http://logicalit.biz/forumimages/140819-202728-0005.jpg

The quality of the kit is pretty good.  The servos are not the best 
quality, but heaps of torque, and plenty accurate enough for the job I 
suspect.

Weight like this is about 1.2 kilos... Not measured it accurately yet, 
must do that.

Fitted an arduino mega with a prototype shield on top between the two 
plates.

http://logicalit.biz/forumimages/140819-202826-0006.jpg

Which leads to the inevitable wiring shambles where 18 servo cables land 
in a small space.  I'll have to come up with a better plan for that.  
Probably distribute the servo headers around the edge of a board and 
route/cable tie things up nice and tidy somehow.

I've split the power into left/right bus, per the wires hanging out for 
the tethered testing.

On the power front, for those who've never bothered to look into one of 
these things.  Guestimate is I need 12A to make it walk using a dynamic 
gait.

Just having it 'stand there' with all servos at mid position requires a 
measured 3.5A at 6V to stop it gently resting on it's belly while making 
an unhappy-servo buzzing noise.

My bench supply does 2A and moving all the servos at the same time 
off-load with the bot sitting on a stand makes it slump to 3-2V which in 
turn causes some interesting servo gyrations as the servo regulator for 
the feedback pot drops out somewhere around 3V judging by what happens. :-)

The power plan is for a high discharge capable LiPo and a pair of 8A RC 
UBEC units feeding one side each. (small switch mode power supplies)

So far software wise all I've done done is some basic fixed position 
testing.  Work on configuring / debugging the phoenix code will be for 
another day, that's not a trivial undertaking but the code base looks 
pretty well organised and I didn't feint reading through it. :-)

A couple of other random pics:

http://logicalit.biz/forumimages/140819-202922-0001.jpg
http://logicalit.biz/forumimages/140819-203026-0003.jpg

Onwards, and upwards.

Cheers, Chris H.