Method and apparatus for estimating a position of a target

• US 5,130,934 A
• Filed: 07/13/1990
• Issued: 07/14/1992
• Est. Priority Date: 07/14/1989
• Status: Expired due to Term

• Current Assignee: Nec Toshiba Space Systems, Ltd. (NEC Space Technologies, Ltd.)
• Original Assignee: Kabushiki Kaisha Toshiba (Toshiba Corporation)
• Inventors: Ikeuchi, Masayuki
• Primary Examiner(s): Black, Thomas G.
• Application Number:
  US07/552,070
• Time in Patent Office: 732 Days
• Field of Search: 364/516, 364/459, 364/434, 364/559, 244/164, 244/169
• US Class Current: 700/90
• CPC Class Codes: G01C 21/14 by recording the course traversed by the object G01C21/16 takes precedence
• CPC Class Codes: G01S 19/485 whereby the further system is an optical system or imaging system
• CPC Class Codes: G01S 19/49 whereby the further system is an inertial position system, e.g. loosely-coupled
• CPC Class Codes: G01S 5/163 Determination of attitude using inertial means G01C9/00; control of attitude G05D1/49
• CPC Class Codes: G05D 1/12 Target-seeking control

Abstract

A position estimation apparatus is adapted to estimate the position of a target in the steps as will be set forth below. The target is observed four or more times by an image sensor during a time period in which the target and movable body unit move in those directions not parallel to each other. Acceleration is applied to an accelerator at least once at a time between the observation times. Two-dimensional angle information of the target'"'"'s azimuth and elevation angles is detected from the image information of the target acquired by the image sensor at the time of observation. A coordinate system of the movable body unit is found in accordance with the position and attitude information of the movable body unit, and the two-dimensional angle information of the target is plotted on the coordinate system. Simultaneous equations are prepared by sequentially substituting the two-dimensional angle information of the target obtained through the observation into an equation of motion representing a regulator motion of the target initially entered on a position estimation apparatus. Parameters in the equation of motion is found from the simultaneous equations. The position of the target at a given time is estimated by substituting the parameters into the equation of motion and the given time into the latter equation.

Claims

1. A position estimation apparatus mounted on a movable body unit to estimate a position in a given time of a target which moves regularly, which comprises:

an accelerator for applying acceleration to the movable body unit;

state detection means for detecting position and attitude information of the movable body unit;

an image sensor for acquiring the target as an image from the movable body unit;

observation control means for making four or more observations of the target, by said image sensor, during a period of time when the target and movable body unit are moved in those directions not parallel to each other and for applying acceleration by said accelerator to the moving body unit at least once at a point of time between the respective observations;

angle information detecting means for detecting two-dimensional angle information of target'"'"'s azimuth and elevation angles from the image information of the target acquired by the image sensor at the time of observation;

coordinate transformation means for finding a coordinate system of the movable body unit at the time of observation in accordance with the information obtained by the state detection means and for plotting, on the coordinate system the two-dimensional angle information of the target which is obtained by the image sensor; and

arithmetic operation processing means, initially stored with an equation of motion representing a regular motion of the target, for preparing simultaneous equations by sequentially substituting, into the equation of motion, the two-dimensional angle information of the target which is obtained through the observation, for finding parameters in the equation of motion from the simultaneous equations and for estimating a target position at a given time by substituting the parameters into the equation of motion and substituting given time data into the resultant equation of motion.

2. A position estimation method for estimating a position in a given time of a target of a regular motion, on a position estimation apparatus, comprising the steps of:

(1) entering into the position estimation apparatus an equation of motion representing the regular motion of the target;

(2) setting observation times four or more times during a period of time when the target and a movable body unit move in those directions not parallel to each other;

(3) applying acceleration to the movable body unit at least once during the period of time set by step (2);

(4) acquiring the target as an image at the observation time set by step (2) and detecting two-dimensional angle information of the target'"'"'s azimuth and elevation angles from the image information;

(5) detecting position and attitude information of the movable body unit, finding a coordinate system of the movable body unit at the time of observation and plotting, on the coordinate system, the two-dimensional angle information of the target which is obtained by step (4); and

(6) preparing simultaneous equations by sequentially substituting into the equation of motion the two-dimensional angle information at a respective time of observation obtained at step (5), finding parameters in the equation of motion from the simultaneous equations; and

estimating a position in a given time of the target by substituting the parameters into the equation of motion and substituting the given time into the equation of motion.