Measurement and control system for scanning sensors
First Claim
1. 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.
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Accused Products
Abstract
A sensor may be scanned relative to any arbitrarily selected reference coordinate system by the use of a system including an attitude determination unit, attitude control unit, inertial measurement unit, navigation unit, and a scan generation unit. Methods are also employed, in this system, for reducing errors and increasing the accuracy of the scan of the sensor. These methods include the use of gyroscopes having no cross axis coupling or inherent limit on their angular speed, a Kalman filter to reduce system errors, continually estimating solutions to the strapdown equation, and a dual loop control system utilizing both rate and position signals which issues motion control commands to the sensor.
36 Citations
25 Claims
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1. A measurement and control system comprising:
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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. - View Dependent Claims (2, 3, 4, 5)
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6. A measurement and control system comprising:
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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. - View Dependent Claims (7, 8, 9, 10)
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11. A measurement and control system employing a sensor which is scanned, said system comprising:
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(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. - View Dependent Claims (12, 13, 14, 15, 16)
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17. In a measurement system employing a scanning sensor, the improvement comprising:
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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. - View Dependent Claims (18, 19, 20)
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21. A method for causing a scanned sensor to follow any path relative to an arbitrarily selected reference coordinate system, said method comprising:
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(a) selecting a reference coordinate system in which said sensor is to be rotated; (b) generating the orientation of said reference coordinate system relative to a desired sensor coordinate system, and inputting said orientation to control processing means for generating control signals to said sensor; (c) generating the angular rate of said desired coordinate system relative to said reference coordinate system in terms of said desired coordinate system, and inputting said measurement to said control processing means; (d) measuring the angular rate of said reference coordinate system relative to an inertial coordinate system and expressing said measurement of angular rate in terms of said reference coordinate system, and inputting said measurement to said control processing means; (e) measuring the angular rate of said sensor coordinate system relative to said inertial coordinate system and expressing said measurement of angular rate in terms of said sensor coordinate system, and inputting said measurement of angular rate to strapdown equation processing means and to said control processing means; (f) measuring the initial orientation of the inertial coordinate system relative to said sensor coordinate system and inputting said measurement of initial orientation of the inertial coordinate system relative to said sensor coordinate system to said strapdown equation processing means; (g) measuring the orientation of the inertial coordinate system with respect to the reference coordinate system and inputting said measurement orientation to multiplication processing means for combining signals; (h) coupling the output of said strapdown equation processing means to an input of said multiplication processing means; and (i) coupling the output of said multiplication processing means to said control processing means. - View Dependent Claims (22, 23, 24, 25)
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Specification