Method and system for decoupling structural modes to provide consistent control system performance

A method of estimating dynamics of a structural system, comprising:

• interconnecting a plurality of subsystems together as a housing subsystem, each of the plurality of subsystems including a rotating member;
• mounting the housing subsystem on an isolation subsystem at one or more degrees of freedom for isolating the housing subsystem from a surface subsystem;
• determining one or more transfer functions of interest for the housing subsystem mounted on the isolation subsystem at a plurality of degrees of freedom;
• and
• creating a control force transfer function based on the determining of the one or more transfer functions of interest, the control force transfer function determining a control force applied to the rotating member;
• and
• wherein the interconnecting of the plurality of subsystems together as the housing subsystem further comprises defining the housing subsystem as a two-mass subsystem where an active member within the housing subsystem moves in a direction opposite that of an outer housing member of the housing subsystem, and positioning the active member at a predetermined displacement relative to the outer housing.

A method of optimizing performance of a control system comprising:

• interconnecting a plurality of rotor housings that each include a rotor and an actuator between the rotor and the rotor housing as one rotor housing;
• connecting the one rotor housing to a spacecraft by mounting the one rotor housing to an isolation subsystem at all axes of structural communication between the one rotor housing and the isolation subsystem while preventing structural communication from the one rotor housing to the spacecraft;
• and
• determining an actuator transfer function for each actuator of the plurality of rotor housings by applying a system transfer function formula to all transfer functions of the plurality of rotor housings at all degrees of freedom as follows:
• y/u=−ΣYRy*u+ΣYHy*u,
• wherein y represents a velocity of displacement between the rotor and the one rotor housing, u represents a control force, ΣYRy represents a sum of rotor transfer functions at respective degrees of freedom, and ΣYHy represents a sum of one rotor housing member transfer functions at respective degrees of freedom;
• and
• repositioning each of the plurality of rotors to a predetermined position within the respective rotor housing by applying the control force to the rotor via the actuator.