XRobots blog

XRobots.co.uk blog

Saturday, June 03, 2006

Working as planned so far...

The current situation is that the android is able to lean side-to-side a few times at about one second intervals between leaning each way, if the gyro says it's not stable enough to lean back the other way after that second then it waits 100ms (0.1 seconds) and checks again... Then another 100ms until it the gyro data is between certain constraints. Basically I'm trying to find the Zero Moment Point (ZMP) which is when the gyro effectively reads 'centred' and there is no momentum in either direction. You can tell some delays are longer than others because you can hear the relays clicking, a bit of fine tuning to do though because although it doesn't fall over it's sometimes close so I need to turn up the sensitivity I think.

I've got a few things to resolve with mounting the batteries inside it which I'm now using instead of the mains power supplies - and I've had far less trouble with the Picaxes hanging due to the long wires and spikey load/unhappy PSUs/back EMF/noise etc. One of the gear boxes got damaged when the motor got stuck 'on' due to this and the pot shaft that was attached to it also sheared as a result... So there's no issue with the strength of the gearboxes, I just have to be more careful not to abuse them. Might implement end switches at some point.

When the replacement gearbox arrives (and my other Picaxe board / chips as mentioned in the article), then I'll be hopefully putting up a video of it leaning side to side with some degree of dynamic control. All that remains after that to make it walk will be triggering the leg controllers to do the right thing at the right time during the main dynamically stable leaning loop.


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