Measurement and control system for scanning sensors

Claim 2

A measurement and control system comprising: a scanning sensor; means for controlling the motion of said sensor with respect to a sensor coordinate system; inertial measurement system for measuring angular rate of said sensor; attitude determination unit for determining the relationship between the sensor coordinate system and a reference coordinate system; and sensor attitude control unit coupled to said attitude determination unit for providing motion control commands to said means for controlling the motion of the sensor, said sensor attitude control unit comprising dual loop processing means for controlling said sensor.

Claim 3

The attitude control unit of claim 1 wherein said dual loop processing means utilizes both rate and position loop processing means.

Claim 4

The attitude control unit of claim 2 wherein the output of said dual loop processing means comprises a combination of the outputs of said rate and position processing means and wherein said dual loop processing means output is connected to motion control means on said sensor for controlling said sensor's rate and position.

Claim 5

The attitude control unit of claim 2 wherein inputs to said rate loop processing means comprise: (a) the angular rate of a reference coordinate system relative to an inertial coordinate system expressed in terms of the reference coordinate system; (b) the angular rate of a desired sensor coordinate system relative to the reference coordinate system expressed in terms of the desired coordinate system, and (c) the angular rate of a sensor coordinate system relative to the inertial coordinate system expressed in terms of the sensor coordinate system.

Claim 6

The attitude control unit of claim 2 wherein inputs to said position loop processing means comprises: (a) the position of a reference coordinate system relative to a desired sensor coordinate system; and (b) the position of a sensor coordinate system relative to the reference coordinate system.

Claim 7

A measurement and control system comprising: a scanning sensor; a scanning generation unit for defining a predefined path for said sensor; control device coupled to said scan generation unit for moving said sensor along said predetermined path; attitude determination unit for continuously estimating a solution based on a strapdown equation; and attitude control unit coupled to said attitude determination unit for determining motion control commands based on said strapdown equation solution, said commands being transmitted to said control device.

Claim 8

A measurement and control system comprising: a scanning sensor; a scanning generation unit for defining a predefined path for said sensor; control device coupled to said scan generation unit for moving said sensor along said predetermined path; attitude determination unit for continuously estimating a solution based on a strapdown equation; and attitude control unit coupled to said attitude determination unit for determining motion control commands based on said strapdown equation solution, said commands being transmitted to said control device.

Claim 9

The system of claim 6 wherein said measurement and control system further comprises Kalman filter means for reducing errors associated with said processing means.

Claim 10

The system of claim 7 wherein said Kalman filter means has a fiducial residual input signal.

Claim 11

The system of claim 8 wherein said Kalman filter means has an output signal comprising an error estimation of said fiducial residual signal.

Claim 12

The system of claim 6 wherein said measurement and control system causes said scanned sensor to follow any arbitrary commanded rotational motion defined relative to any arbitrary reference coordinate system.

Claim 13

A measurement and control system employing a sensor which is scanned, said system comprising: (a) scan generation means for providing a first signal representing a position of a reference coordinate system relative to the position of a desired sensor coordinate system, and a second signal representing an angular rate of the desired sensor coordinate system relative to the angular rate of the reference coordinate system, said second signal being expressed in terms of said desired sensor coordinate system; (b) inertial measurement means, connected to said sensor, having gyroscopic means for providing a third signal representing an angular rate of the sensor relative to an inertial coordinate system, said third signal being expressed in terms of a sensor coordinate system; (c) navigation means for providing a fourth signal representing the angular rate of the reference coordinate system with respect to the inertial coordinate system, said signal being expressed in terms of the reference coordinate system, and a fifth signal representing the position of the inertial coordinate system relative to the reference coordinate system; (d) attitude determination means, coupled to the inertial measurement and navigation means, for receiving the third and fifth signals, as well as signals representing the position of the inertial coordinate system with respect to the sensor coordinate system at measurement system initialization, the position of a sensor line of sight coordinate system with respect to the sensor coordinate system, and a fiducial residual signal representing error associated with angular position measurement of a known body; said attitude determination means generating a sixth signal representing the position of the sensor coordinate system relative to the reference coordinate system, and a seventh signal representing the position of the sensor line of sight coordinate system relative to the reference coordinate system; (e) sensor attitude control means for receiving the first, second, third, fourth and sixth signals and generating an output signal providing motion control commands; and (f) motion control means for moving the sensor in response to motion control commands received from said attitude control means whereby said sensor is scanned with respect to any arbitrarily selected reference coordinate system.

Claim 14

A measurement and control system employing a sensor which is scanned, said system comprising: (a) scan generation means for providing a first signal representing a position of a reference coordinate system relative to the position of a desired sensor coordinate system, and a second signal representing an angular rate of the desired sensor coordinate system relative to the angular rate of the reference coordinate system, said second signal being expressed in terms of said desired sensor coordinate system; (b) inertial measurement means, connected to said sensor, having gyroscopic means for providing a third signal representing an angular rate of the sensor relative to an inertial coordinate system, said third signal being expressed in terms of a sensor coordinate system; (c) navigation means for providing a fourth signal representing the angular rate of the reference coordinate system with respect to the inertial coordinate system, said signal being expressed in terms of the reference coordinate system, and a fifth signal representing the position of the inertial coordinate system relative to the reference coordinate system; (d) attitude determination means, coupled to the inertial measurement and navigation means, for receiving the third and fifth signals, as well as signals representing the position of the inertial coordinate system with respect to the sensor coordinate system at measurement system initialization, the position of a sensor line of sight coordinate system with respect to the sensor coordinate system, and a fiducial residual signal representing error associated with angular position measurement of a known body; said attitude determination means generating a sixth signal representing the position of the sensor coordinate system relative to the reference coordinate system, and a seventh signal representing the position of the sensor line of sight coordinate system relative to the reference coordinate system; (e) sensor attitude control means for receiving the first, second, third, fourth and sixth signals and generating an output signal providing motion control commands; and (f) motion control means for moving the sensor in response to motion control commands received from said attitude control means whereby said sensor is scanned with respect to any arbitrarily selected reference coordinate system.

Claim 15

The measurement and control system of claim 11 wherein said gyroscopic means is unaffected by cross axis errors and said gyroscopic means is operable at any selected angular acceleration or rate.

Claim 16

The measurement and control system of claim 11 wherein said attitude control means comprises dual loop control processing means, utilizing both position and rate signals, for reducing tracking errors associated with said sensor.

Claim 17

The measurement and control system of claim 11 wherein said attitude determination means comprises processing means for continually approximating solutions based on a strapdown equation.

Claim 18

The measurement and control system of claim 11 wherein said attitude determination means comprises Kalman filter means to which is input said fiducial residual signal and whose output represents estimated errors of measurements associated with said inertial measurement means, said attitude determination means, said fiducial residual signal, and the position of the sensor line of sight coordinate system relative to said sensor coordinate system.

Claim 19

The measurement and control system of claim 11 wherein said reference coordinate system is rotating relative to said inertial coordinate system.

Claim 20

In a measurement system employing a scanning sensor, the improvement comprising: inertial measurement means, connected to said scanning sensor, having gyroscopic means for providing a signal representing an angular rate of the sensor relative to an inertial coordinate system, said signal being expressed in terms of a sensor coordinate system; and wherein said gyroscopic means is unaffected by cross axis errors and is operable at any selected angular acceleration or rate.

Claim 21

In a measurement system employing a scanning sensor, the improvement comprising: inertial measurement means, connected to said scanning sensor, having gyroscopic means for providing a signal representing an angular rate of the sensor relative to an inertial coordinate system, said signal being expressed in terms of a sensor coordinate system; and wherein said gyroscopic means is unaffected by cross axis errors and is operable at any selected angular acceleration or rate.

Claim 22

The improvement of claim 17 wherein said measurement system comprises Kalman filter means for reducing errors associated with said gyroscopic means.

Claim 23

The improvement of claim 18 wherein said Kalman Filter means receives a fiducial residual input signal.

Claim 24

The improvement of claim 19 wherein said Kalman filter means has an output signal comprising an error estimation of said fiducial residual input signal.

Claim 27

The method of claim 21 wherein Kalman filter means is connected to said strapdown equation processing means for reducing errors associated with the estimation of said strapdown equation.

Claim 28

The method of claim 21 wherein said processing control means comprises dual loop processing control means, utilizing both rate and position signals, for adjusting said sensor's rate and position.

Claim 29

The method of claim 23 wherein outputs of said position and rate control processing means are combined together to generate motion control signals to said sensor.

Claim 30

The method of claim 21 wherein said strapdown equation processing means continuously estimates solutions to said strapdown equation.