LinuxCNC delta robot

I considered building a delta robot for a long time. It's well known, but I was interested how rotary actuators work and how fast the robot can actually move. The main problem is rotary actuators stiff enough with high torque.
Recently I had a chance to purchase a few small harmonic reducers size 14 with 50W Yaskawa servo motors for a decent price. The reducers have cross roller bearing incorporated, so I just needed to install the reducers to the plate and screw the robot arms to their output plates. Robot arms and parallelograms were made of light aluminium tubes. The joints consist of steel balls and aluminium sockets.
Delta robot control is definitely a job for LinuxCNC. I used MESA 7i43 and 7i48 boards to control Yaskawa SGDH-A5 servo drives in analog velocity mode. Tuning PID and servo drives setting is the most difficult part. It's hard to get oscillation-free positioning with high acceleration. S-curve acceleration would be extremely useful for delta robots, but LinuxCNC does not support it (yet, I hope).

More photos and videos coming.