The system shown is an off-axis drive system that rotates the platform to 60° via a substantially-sized NEMA 34 stepper motor. The axial force required by the stepper/ballscrew assembly has already been determined. The maximum axial load on the ballscrew occurs at 40° and is approximately 150lb-force or ≈ 670N. The linear rail is a dual-rail quad-bearing carriage system capable of supporting over 5x the load weight. The stepper motor also will never reach a rotational velocity of more than 2.4 rev/sec and will be operated at full step to maximize torque. (200 ppr or 1.8° per step) The maximum motor torque required at the greatest load point is 1.7Nm. The stepper we have chosen provides 5.6Nm. Long story short, the system is not lacking in power or structural integrity in any way.
However, the system will be operated at specified degree points at low-stepping speeds. For example, it will be stopped at 40°, and then "stepped" in slow increments of 1.8°. I am controlling this via LabVIEW and can rotate the stepper at any number of 1.8° steps per second I choose. This positioning control is 100% open loop and determined by the operator. I am trying to determine the mechanical stability of the system as it is given this "step" input under a load. I'm not sure where to begin with deriving a transfer function or how to model it. As you can see, there are gas springs that assist the operation. Maybe it should be modeled as a spring-dampener system? I am not sure. I have Simulink and would like to be able to model they system in there...I'm just not sure where to start. Thank you.