Yes, it uses solenoid based actuators. Not sure if it controls the dynamics too, but one way to do that would be by driving the actuators using a curve modulated by high frequency PWM; probably quite hard to calibrate to MIDI key velocity since those actuators are essentially on/off devices, but doable.
A very nice project, I'd love to see some more information about it.
Thanks! So - midi velocity translates to PWM and hence solenoid force? Cool. You can always add some kind of mapping function if lower velocities are too low force. Nice work.
(old pre-electronics player pianos could do dynamics but most relied heavily on input from the operator to do so - with various limitations - it's probably a good plan to avoid directly imitating them :-)