US 10,310,054 B2 · Relative object localization process for local positioning system

Abstract

Systems and methods for performing relative object localization using a local positioning system. The process in accordance with one embodiment solves the problem of determining the location (i.e., the position and orientation) of an object relative to a previous location of the object, or relative to another object, without the need for known 3-D data point positions in the environment. The process in accordance with another embodiment solves the problem of determining the location of the measurement instrument relative to a previous location of the measurement instrument using visible feature points on a target object as a reference, again without the need for known 3-D data point positions. The process in accordance with a further embodiment is capable of determining the locations of multiple objects relative to each other.

A method for determining a relative location of a target object, said method comprising:

(a) placing first instances of a positioning system and a target object at respective locations such that the first instance of a target object is within measurement range of the first instance of a positioning system;
(b) specifying first, second and third points corresponding to visible features of or markers on the first instance of a target object, wherein the first, second and third points are not collinear;
(c) measuring respective coordinates of the first, second and third points and a fourth point on the first instance of a target object in a frame of reference of the first instance of a positioning system while the first instances of a positioning system and a target object are at their respective locations using light transmitted by the positioning system toward the first through fourth points on the first instance of a target object in succession;
(d) defining a frame of reference of the first, second and third points on the first instance of a target object based on the measured coordinates of the first, second and third points;
(e) computing a 4×4 current calibration matrix representing a transformation from the frame of reference of the first instance of a positioning system to the frame of reference of the first, second and third points on the first instance of a target object using the coordinates measured in step (c), the 4×4 current calibration matrix including:
(i) first through third columns of a 3×3 rotational matrix representing a difference in orientation of the frame of reference of the first instance of a positioning system and the frame of reference of the first, second and third points on the first instance of a target object, (ii) a fourth column that includes three elements representing a difference in position of an origin point of the frame of reference of the first instance of a positioning system and an origin point of the frame of reference of the first, second and third points on the first instance of a target object, and (iii) a fourth row consisting of the elements 0, 0, 0 and 1;
(f) placing second instances of a positioning system and a target object at respective locations such that the second instance of a target object is within measurement range of the second instance of a positioning system;
(g) measuring respective coordinates of the first, second and third points on the second instance of a target object in a frame of reference of the second instance of a positioning system while the second instances of a positioning system and a target object are at their respective locations using light transmitted by the positioning system toward the first through third points on the second instance of a target object in succession;
(h) computing a displacement matrix that represents a relative position and orientation difference of the first and second instances of a target object in the frame of reference of the first, second and third points on the first instance of a target object using the current calibration matrix and the coordinates measured in steps (c) and (g) and not using predetermined coordinates that specify the locations of the first, second and third points in a coordinate system of the first and second instances of a target object;
(i) computing an updated calibration matrix representing a transformation from the frame of reference of the second instance of a positioning system to a frame of reference of the first, second and third points on the second instance of a target object by multiplying the current calibration matrix by the displacement matrix to create the updated calibration matrix;
(j) storing the updated calibration matrix in a non-transitory tangible computer-readable storage medium accessible to the positioning system;
(k) computing the coordinates of the fourth point on the second instance of a target object in the frame of reference of the second instance of a positioning system using the updated calibration matrix and the coordinates of the fourth point measured in step (c);
(l) aiming the positioning system at the fourth point in accordance with the computed coordinates of the fourth point;
(m) emitting a laser beam from the positioning system while the positioning system is aimed at the fourth point;
and
(n) performing a machining or inspection operation on a portion of the target object that is located at the fourth point.

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Relative object localization process for local positioning system

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Relative object localization process for local positioning system

Life of this patent

Abstract

Claims6