Inertial stabilization system with active jitter suppression and optical control

1 . A method for three-loop inertial stabilization with active jitter suppression and optical control to reduce line-of-sight jitter based on platform induced motion in a gimbal system, the method comprising:

dampening resonances by inertial actuators utilizing a first loop;

tracking out residual jitter utilizing a second loop; and

driving a plurality of stepper motors to keep a fast steering mirror near a middle of its dynamic range utilizing a third loop;

whereby said three loops substantially suppress said line-of-sight jitter of said gimbal system.

2 . The method of claim 1 , further comprising:

using calibrated measurement and calibrated actuation to accurately track residual mechanical jitter.

3 . The method of claim 1 , wherein said first loop comprises:

providing measured rates elevation (EL) and cross-elevation (XL) produced by rate sensors to a Kalman state estimator module;

providing four amplitude and four rate modes by said Kalman state estimator;

inputting said four amplitude and said four rate modes to a linear quadratic regulator;

producing an output of four stators and four masses forces by said linear quadratic regulator; and

inputting said four stators and said four masses forces to a state-space model of a gimbal.

4 . The method of claim 1 , wherein said second loop comprises:

receiving an input laser beam at a mirror system;

receiving bus inertial data at an open-loop closed-loop selector;

outputting received said input laser beam from said mirror system to a focal plane and centroid processing module;

outputting a focal plane and centroid processing to said open-loop closed-loop selector;

providing a direct current (DC) coupled output from said open-loop closed-loop selector to a signal combiner;

inputting measured rates EL and XL to a rate to angle module;

inputting an alternating current (AC) coupled output from said rate to angle module to said signal combiner;

inputting an output from said signal combiner to a loop integrator;

inputting an output from said loop integrator to said fast steering mirror; and

inputting an output from said fast steering mirror to said mirror system.

5 . The method of claim 1 , wherein said third loop comprises:

receiving an input to a fast steering mirror offload module from a loop integrator output;

receiving an input to gimbal motor drivers from said fast steering mirror offload module;

receiving an input of two stators’ and two rotors’ torques at a state-space model of a gimbal from a gimbal motor driver.

6 . The method of claim 1 , further comprising:

suppressing jitter on receive and transmit beams to below 0.8 µrad RMS.

7 . The method of claim 1 , further comprising:

operating an inertial measurement unit in a null mode whereby linearity requirements on said inertial measurement unit are reduced.

8 . The method of claim 1 , further comprising:

accounting for a secondary disturbance of said gimbal motors wherein each said gimbal motor includes 35 µrad 2 millisecond steps.

9 . The method of claim 1 , further comprising:

increasing a gain to frequencies between 30 and 300 Hz.

10 . The method of claim 1 , further comprising:

suppressing residual broadband jitter by a fast steering mirror at a high speed and a small dynamic range.

11 . A computer program product including one or more non-transitory machine readable mediums having instructions encoded thereon that when executed by one or more processors, result in a three-loop inertial stabilization system with active jitter suppression and optical control to reduce line-of-sight jitter based on platform induced motion in cantilevered gimbal systems, the instructions comprising:

executing a first loop comprising:

providing at least one inertial force actuator;

providing measured rates EL and XL produced by rate sensors to a Kalman state estimator module and producing four amplitude and four rate modes by said Kalman state estimator;

inputting said four amplitude and said four rate modes to a linear quadratic regulator and producing an output of four stators and four masses forces by said linear quadratic regulator; and

inputting said four stators and said four masses forces to a state-space model of a gimbal;

executing a second loop comprising:

receiving an input laser beam at a mirror system;

receiving bus inertial data at an open loop closed-loop selector;

outputting received said input laser beam from said mirror system to a focal plane and centroid processing module;

outputting focal plane and centroid processing to an open-loop closed-loop selector;

providing a DC coupled output from said open-loop closed-loop selector to a signal combiner;

inputting measured rates EL and XL from rate sensors to a rate to angle module;

inputting an AC coupled output from said rate to angle module to a signal combiner;

inputting output from said signal combiner to a loop integrator;

inputting output from said loop integrator to a fast steering mirror; and

inputting output from said FSM to said mirror system;

executing a third loop comprising:

receiving input to a fast steering mirror offload module from a loop integrator output;

receiving input to gimbal motor drivers from said fast steering mirror offload module; and

receiving input of two stators’ and two rotors’ torques at a state-space model of a gimbal from gimbal motor drivers;

wherein calibrated measurement and calibrated actuation track residual mechanical jitter; and

whereby said three loops substantially suppress said line-of-sight jitter of said cantilevered gimbal system.