Pulsing Pump Pressure

The variable displacement pump has been playing up recently! When the pressure is reduced to idle, which should be about 14bar, sometimes the pump pulses at around 35 to 45 bar. I took a video of this happening so that I can show the bosch rep. I have checked various signals to the pressure relief valve etc but can't see anything wrong. I also cleared the 0.8mm orifice but again i don't think it was blocked.

Christina and the Mantis

 

My girlfriend Christina pays a welcome visit to the workshop :)

Diesel tank rupture...

 

Well I noticed the diesel level switch was leaking today, just a minor drip, so I tightened the float switch by one quarter turn... walked away, 15 minutes later the sensor popped out and covered the machine and floor in diesel. Great! just what I needed.. So A strip down and de-gunk is on the cards for tomorrow. I guess at least I will have tested the electronics IP65 rating! 

Floor Panels

Finished installing the cab and posterior chassis floor panels which all things considered went on pretty well! I had to take the angle grinder to a few of the pieces and completely chopped up and modified the read cab panel for practical purposes. Also I will need to have the cab side panels re-made, as the drawing was slightly wrong which means the holes for the valves is in the wrong place.

Once I'm happy with all the panels I will remove them and take the for anodizing. I still have to fit the side and bottom chassis panels.

New Engine Mounts

It seemed to me that the engine was sitting a little too low on the rear engine mounts, plus there was a bit too much engine movement, so I have replaced the engine mounts with a harder rubber mount which seems to have improved things.

Another VIC-E controller mod.

We have modified the VIC-E analogue input circuit to include an initial potential divider of 1.2K and 51K, the signal is fed through the 1.2K and into the PIC ADC and one end of the 51K which is joined to ground. This gives a stronger ground pull down, and protects the PIC from excessive input voltages via the 1.2K resistor. This does of course effect the full scale output at 5V input, but I have picked these resistor values so that full scale is now approx 4000 instead of 4095.

Body Velocity Control

Spent a couple of weeks working on the software, primarily to get constant body velocity while walking but still using the balance gesture technique. I think I have a pretty good solution now, although the turn motion control doesn't scale yet, and the maximum velocity does seem slightly limited in certain leg motion modes. This can be tweaked by having special cases for faster movement, but I would rather find a more elegant solution.

Cooler Test

 

I've been testing the cooler in optimum conditions to see if there is any improvement in cooling capacity. Currently the hydraulic fluid is overheating, so OCCO suggested that the cooler needed more free air space around it, hence I pulled it out of the machine and hung it on the crane. Didn't notice much difference, so a two pass cooler has been suggested with a higher flow rate pump.

Overheating

Having had a long chat with one of the engineers at Occo, I spent the afternoon testing the cooling capacity of our hydraulic oil cooler. The system temperature does not seem to stabilize, and worryingly I have hardly used the machine yet! I have been measuring the differential across the cooler, and have been seeing about 8 degrees from in to out, which is not enough given that the ambient temperature is around 18 degs and the inlet temperature around 45. One suggestion from the Occo engineer was to remove the cooler from the chassis and test it in an open space, I did this for the test but I only saw an improvement to approx. 10 degs differential...

 

 

Cooler mounted between the engine and the fuel tank.

Cooler hanging off of our engine hoist to give more free space around the fan and grill

New Tibia Rams

The new 50mm bore tibia rams arrived this morning and I managed to get them all fitted and commissioned by the end of the day. The control I now have over the tibia axis is in a different league! I think the intertial load of the tibia was just too much for the 40mm bore rams, as I now have the PID loop tuned really nicely, just using the P term and MAX/MIN drive. I think the coxa rams would also benefit from the same size rams, however, I'm concerned about the knock on effect of adding an extra tonne of thrust into the coxa position!

Interestingly the new 50mm bore rams are slightly smaller than the Parker 40mm bore rams, and 3.5Kg lighter! When compared to the Parker 50mm bore ram they are about 9Kg lighter!! this would have been a great weight saving for out machine if we had of gone with this make in the first place.. live and learn :)