I think the sub-cpu board is our well-known RC003 board and the main CPU send command to the board through RS232 or RJ45.
The command type can be found in the SDK CD ROM (purchasable)
By the way, how about your full video of your robot with your hands?
really want to see
In your case, about the five wires, any loose after several hand gripping ?
there should be some mechanism to prevent the back-lacklash. In the God-hand there is five holds to prevent the cable-tie to came back, instead of just clipping the five wires together as most of the hobby does
your robot's hand size is very good and good-looking, it may make a business