End of leg rebuild with new joint bearings

Finished re-building the legs with the new joint axle and taper roller bearings. All went together very nicely, much easier than the previous system! Tomorrow I will get the encoders hooked up and start the calibration procedure. The maybe a test!

The New Femur & Tibia Axles

The first Femur axle in place, with half the Coxa and Femur cheeks. 

The completed Femur joint

The occasional stubborn bearing needed this jig to get it started. Thank goodness I add M8 tapped holes in the ends of the axle!

Half way there, all the femurs back on.

Not bad for one days work.. on my own!

And another day with help and the tibia's are back in place.

New joint bearing parts

I picked up the bearing housings from D&T today. I was hoping to get everything but its been delayed until Wednesday, still I'm going to push on and fit the bearing housing to the aluminium cheeks. You can see at the top right of the picture one of the 0.1mm laser cut shims I have had made to offset any cheeks that are of differing thickness. This is because the 25mm sheet aluminium cut parts came in a range of thickness's from 25.0 to 25.4 .

Legs Stripped Down... Again!

Ok, this has to be the last time! after carrying out further tests on the joints I have decided that the current spherical eye bearings are not up to the job, and although are plenty strong enough, they are allowing far too much mechanical play in the joints which is not helping the stability of the machine. So its time to re-engineer the joints with taper roller bearings similar to the coxa joint that was altered last year.

The first of six legs stripped.

Sandy came in to help me out.

Nearly finished, looks kind of cool.

All done! I bet the re-build doesn't go so smoothly!

I also decided to order more powerful rams for the coxa joints. Although the existing rams have plenty of power when pushing, the pull force is half which makes the joint tuning very difficult. With the improvement I have already seen in the tibia rams I think the coxa rams will also benefit from a larger bore 50mm cylinder.

New Cooler pipe work

Here is the new cooler pipe work layout. The cooler sits horizontal when mounted so the filter will end up in a vertical position.

Cooler baffle Issue

Well this would be why our cooler wasn't doing much cooling, check out the gape around the baffle!

The Bad!

And this is what is should have looked like.

TheGood!

Our Third oil cooler!

The third oil cooler arrived, lets hope it right!

Progress!

Finally some things are starting to work a little more predictably. The rebuild was well worth while, in particularly the new ground contact sensors are working as I would expect making things much easier to tune.

Rubbish DiPERK Exhaust cracked

Exhaust has cracked after 50hrs of engine use! I contacted DiPerk who supplied the exhaust with our Perkins engine, but they tell me it has cracked due to excessive vibration.. erm, its your engine that its attached to! Mounted on four rubber shock mounts to a chassis that is pretty much stationary! They are number two on my list of companies not to deal with again! If I had more time I would badger them for a new one, as IMO this is Not Fit For Purpose!

Inside the new hydraulic tank

First post of 2012

Been working on the software for the last few weeks. The new gait generator is coming together I think.. although I still have allot of testing to carry out. It's not as neat or simple as the original gait generator, but I can at least control the legs in a more predictable way. I ran a turning simulation with a pen attached to the simulated hexapod which allowed me to trace the motion, pretty neat! The smallest circle is using the slowest gait, the larger circles were tripod and one/two leg gaits.

You can also see I have spent some time creating the BEV (Birds Eye View) of the hexapod within the simulation screen which has helped a great deal while developing the new gait generator.