Resolution depends on the encoder. An absolute 20 bit encoder can have 1048580 counts per revolution. You can get more counts per revolution.
The advantage of an RMC is that it has feed forward so there is no lag between the motion profile and the actual motion. A lot depends on the inertia and speed of the rotation. Digital cylinders have no feed forward, they only have a mechanically fixed proportional gain so it cannot be changed to accommodate different inertias. RMCs can move heavier loads faster without overshooting. There are many good servo valves. The real problem is the friction within the motor.
The problem with the digital cylinder and motor is that it has poor speed control because there is no feedback. The motor or cylinder is given pulses, and it assumed the actual position or angle will be the proportional to the number of pulses but it isn’t because the digital cylinder and motor have only mechanical proportional control that can’t be adjusted. There is always a phase lag which means the actual velocity will never be the same as the actual velocity when the system is accelerating like when ramping up or down or following a sine wave as in testing.
How do you know if the digital cylinder is accurate when there is no feedback. You can only hope the digital motor or cylinder goes where you want it to go. RMCs can use Balluff or Temponic rods with 0.1 micrometer feedback resolution. I have shown videos doing fine control in the past. Yes, we have special algorithms that consider the natural frequency, damping factors and the fact that a hydraulic actuator is a mass between two springs unlike a motor so the algorithms must be enhanced over that of a PID used in motor. That is what makes the RMC motion controller special. The RMC Motion control has “auto tuning” or auto optimization that makes calculating the controller gains easy.
deltamotion.com/peter/Videos/Optimizing Gain- Chinese.mp4
It takes me only about 1 minute to optimize a hydraulic actuator. This video takes longer because Gan is explaining everything step by step.
Notice that the RMC knows where the actuator should be and where it really is every millisecond or half millisecond. The RMC has Ethernet connectivity so one can monitor everything in real time. Also, recently we added Ethercat. This allows the RMC200 to access many hydraulic valves and motors that use Ethercat as an interface well as Ethercat I/O modules.
Delta Motion has lots of videos.
Delta Motion
About me.
I announced that I retired 4 years ago.
My business partner and I sold Delta Motion to the employees.
This is called an Employee Stock Ownership Plan.
My business partner is still running the company for now.
I try to show up at the office once a week.
I am now a citizen of St Kitts and Nevis, but I don’t live there.
I am going to move to Panama. I have my temporary visa, but I am waiting for my permanent pensioner’s visa.