When everything is powered up, this converted robot arm carries out coordinated six-axis movements under the control of LinuxCNC's kinematics module. The base machine is a surplus Fanuc R-2000iA/200F, a 1.5 ton arm that still wears its RO8 stencil. Excessive Overkill took hardware that most of us would walk past and turned it into something that moves like a proper multi-axis machine tool.
The path there was anything but simple. The original Fanuc controller carried mismatched firmware, which produced incorrect joint scaling and kinematics errors, and the answer was to move control over to LinuxCNC running on a Dell PC with a Mesa FPGA expansion card. The whole controller lives in a yellow rugged case, with Allen-Bradley safety relays and cooling inside, plus four 12V server supplies alongside two 24V units. Motion runs on open-source ODrive controllers refreshing at 300 Hz.
The detail that stands out most to me is the encoder work. The maker reverse-engineered the serial signaling with an oscilloscope and a logic analyzer, worked out that it was a two-wire half-duplex RS-422 scheme, and then wrote custom VHDL so the Mesa card could decode the two-wire Fanuc encoders directly. That link runs at 2.7 Mbaud with an 8 kHz request rate, and servo PID following errors came in at up to 0.2 degrees, which sounds tidy for hardware this size.
The one open trade-off is speed. Right now the top speed sits at roughly 10%, since the 48V supply is a long way below the motors' standard rating of around 200V. That leaves a lot of performance on the table, but even at a crawl this is an impressive piece of work.
Project by Excessive Overkill. Watch it on their YouTube channel: