Assembling Rocky

     The past few weeks have been incredibly busy. We're collecting everything necessary to finish building Rocky, our omni-directional force-controlled rough terrain vehicle, including the structure, drive trains, motors, embedded computers, power systems, suspension, and plenty more. Currently, almost everything is still "in progress". Only a few parts are actually complete.


We have a lower frame. If I do say so myself, it is a very nice frame.


We have drive trains, three of them, just about complete. Now we're calibrating/adjusting everything. The vehicle will be force-controlled, and that means that end-to-end, the actuators/drive trains need to have close to zero backlash. That means no gears, no flexible components, and minimal slip. To accomplish this we're using harmonic drives, timing belts, and very high-friction traction components. For force sensing we're using reaction torque sensors connected to each motor.
   The second major requirement of effective force control is that we need near zero latency in the control loop from sensors to actuators (sensors->low level controllers->high level controllers->low level controllers->actuators << 1 ms). To accomplish that we're installing a lovely embedded PC with high speed digital and analog IO, onboard DSPs for low level control, and running a hard realtime variant of Linux. All that to come via misspelled, sleep deprived blog posts in the near future.

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