controlling the amplification of the modes and keeping the SRS within specification at high  frequencies. Fixture modes can be estimated using finite element analysis  •Ensure that dynamic models used for motor verification have high accuracy in the electrical portion of the model – do not rely on past models or electronics engineering to provide a good model. Go through every detail and understand every component modeled, and perform checks against prototype data, such as BEMF plots to verify realistic behavior of model. •Voltage versus current plots for most electrical components can be easily found on the internet – Simulation of the electrical component should match the expected voltage versus current behavior before adding it into the stability model. •Make sure a high enough number of steps is modeled, since the torsion windup of the harmonic drive or other factors can allow a motor to step stably for 25 or even 50 steps before losing stability. This is more of an issue when the motor does not have enough torque margin. •Validate and calibrate the stability model early in the hardware development effort. •Even if the model used has a good track record, and only the values for the various parameters are being updated, model calibration should be performed once prototype data is available. •Motor-level prototype test data can allow for earlier validation of the electronic portion of the model, provided the motor is driven by flight-like drive electronics. If this data is available, the stability model can be chopped down to just the drive electronics and motor rotor, and compared to the motor-level test data. •Driving the motor with flight-like drive electronics should be performed as early in the development process as possible. All motor level testing should include flight-like drive electronics. •Motor hysteresis will decrease as temperature increases due to recoverable decrease in magnet strength. Motor designs should not rely on motor hysteresis (or friction!) to maintain stability at hot. •Loss of motor hysteresis at hot can be estimated based on data from the magnet supplier. Since detent is usually measured at ambient only, use this data to “knock down” the minimum hysteresis torque value input to the stability model. •Checking the motor operating point on the magnet B-H curve is recommended as operation at hot can lead to permanent demagnetization if the minimum permeance coefficient is too low. Demagnetization during operation at hot can also reduce detent torque and cause a loss of step stability. •Poor detent characteristics are a red flag for a poorly designed motor. In the world of motor design, there are usually many options for stator tooth count in a given step size and phase count, even though the rotor pole count cannot be adjusted. •Design the motor to take advantage of the drive electronics architecture – The drive electronics for the CSADA, although unusual and seemingly not conducive to stability, provide a significant amount of extra damping when needed if the motor design is properly optimized. References  1. Kackley, Russel & McCully, Sean. "Stepper Motor Instabilities in an Aerospace Application." Proceedings of the 26th Aerospace Mechanisms Symposium  (1992), 173-187. 2. Marks, D.B. "Integrating motion simulation with design for space stepper motor applications." Proceedings of the 6th European Space Mechanisms & Tribology Symposium , (1995), pp. 413-418. NASA/CP—2018-219887 306