Thursday, 10 December 2009

The leg lives!! Very EXCITING :)

Yes, today we have the leg moving under hydraulic control.. Ok, so its only one joint of one leg, but it feels like a major mile stone, and also slightly terrifying :)

We started with simple open loop control of the valve at 50bar, so that we could drive the cylinder from one end to the other. This was working pretty well, although a little underpowered on the annulus upstroke when lifting the weight of the leg. However, we were only running at 50bar. At first we had the tibia down in contact with the floor, I drove the leg in the wrong direction, eg, towards the floor. To our surprise even at this low pressure the leg started to move our test rig which is bolted to the floor and wall.. that's the terrifying part :)

Next we got the leg running under closed loop control and at a higher pressure of 75bar, it's all going pretty well considering its our first hydraulic test, however, we have quite a bit of air in the system which isn't helping. We will spend more time on Monday bleeding the system and give the leg a power test. Josh has an idea of using our engine hoist to check the femur power.. kind of hoist versus leg.. to be continued.