US 2019/0098221 A1 · Methods for Measuring and Inspecting Structures Using Cable-Suspended Platforms

Abstract

Systems and methods for measuring the distance to a target object and acquiring three-dimensional coordinates, scale information, and point-to-point distance information for that target object in an environment using a remotely operated cable-suspended platform. The system uses on-board sensors and processing techniques to provide discrete or continuous measurements of the distances between points on a target object or the scale of the target object. The addition of on-board three-dimensional measurement capabilities to cable-suspended platforms enables these systems to acquire three-dimensional position data defined in the coordinate system of the environment, determine distances between objects or between points on the same object. The system can also be used to determine the scale factors of items in images captured by a camera carried by the cable-suspended platform, in the course of performing metrology-related tasks.

Claims26

Dependent claims

A method for calculating a position of a point of interest on a target object in a frame of reference using a cable-suspended platform comprising an equipment support member, a pan-tilt mechanism mounted to the equipment support member, a camera mounted to the pan-tilt mechanism, and a laser range meter affixed to the camera, the method comprising:

(a) suspending the cable-suspended platform from a plurality of cables connected to the equipment support member and supported at respective anchor points of a plurality of anchor points;
(b) calibrating the pan-tilt mechanism relative to the frame of reference;
(c) controlling lengths of paid-out portions of the plurality of cables in a manner that causes the equipment support member to move so that the camera is within range of a target object;
(d) measuring respective distances of a center point of the equipment support member from respective anchor points based in part on the lengths of the paid-out portions of the plurality of cables;
(e) controlling the pan-tilt mechanism to cause the laser range meter to aim at a point of interest on the target object;
(f) measuring the pan and tilt angles of the pan-tilt mechanism while the laser range meter is aimed at the point of interest;
(g) measuring a distance separating the laser range meter and the point of interest;
and
(h) converting the distance and angle measurements into a Cartesian coordinate vector representing the position of the point of interest in the frame of reference.

6 more elements

A method for inspecting and measuring a structure comprising:

(a) suspending a cable-suspended platform from cables in a vicinity of a structure;
(b) controlling the cable-suspended platform to move toward the structure;
(c) using first and second laser range meters on-board the cable-suspended platform to repeatedly measure first and second distances respectively separating the first and second laser range meters from respective first and second spots on a surface of the structure while the cable-suspended platform is moving;
(d) calculating a first separation distance separating the cable-suspended platform from the structure based at least on the first and second distances;
(e) determining whether the first separation distance equals a goal offset;
(f) controlling the cable-suspended platform to stay at a first location separated from the structure by the first separation distance in response to a determination in step (e) that the separation distance is equal to the goal offset;
(g) using a camera on-board the cable-suspended platform to capture a first image of the structure while the cable-suspended platform is at the first location;
and
(h) displaying the first image on a display screen.

6 more elements

A method for inspecting and measuring a structure comprising:

(a) suspending a cable-suspended platform from cables in a vicinity of a structure;
(b) controlling the cable-suspended platform to move to and then stay at a location separated from the structure;
(c) directing first and second laser pointers pivotably mounted on-board the cable-suspended platform in parallel toward a surface of the structure, respective pivot axes of the first and second laser pointers being separated by a fixed distance;
(d) using the mutually parallel first and second laser pointers to transmit mutually parallel laser beams onto first and second spots respectively while the cable-suspended platform is at the location;
(e) using a camera on-board the cable-suspended platform at a first time to capture a first image of a portion of the surface of the structure that includes the first and second spots;
(f) pivoting the first and second laser pointers by a predefined angle while the cable-suspended platform is at the location so that the first and second laser pointers are no longer parallel;
(g) using the pivoted first and second laser pointers to transmit non-parallel laser beams onto respective third and fourth spots on the surface of the structure while the cable-suspended platform is at the location;
(h) using the camera at a second time to capture a second image of the portion of the surface of the structure that includes the third and fourth spots;
and
(i) processing the first and second images to calculate a first separation distance separating the cable-suspended platform from the structure based on positions of the third and fourth spots in the images, the predefined angle and the fixed distance separating the pivot axes of the laser pointers.

7 more elements

A method for sizing a feature of a structure using a cable-suspended platform comprising a pan-tilt mechanism that supports a camera and a laser range meter, the method comprising:

(a) suspending the cable-suspended platform from a plurality of cables supported at respective anchor points of a plurality of anchor points;
(b) controlling lengths of paid-out portions of the plurality of cables in a manner that causes the cable-suspended platform to move to a first location;
(c) measuring respective distances of a center point of the cable-suspended platform from the respective anchor points based in part on the lengths of the paid-out portions of the plurality of cables when the cable-suspended platform is at the first location;
(d) aiming the laser range meter at a first point corresponding to a first visible feature on a surface of the structure while the cable-suspended platform is at the first location and acquiring a first distance measurement;
(e) using the pan-tilt mechanism to measure the respective pan and tilt angles of the laser range meter when the laser range meter is aimed at the first point;
(f) converting the distance and angle measurements acquired in steps (d) and (e) into a first vector representing the location of the first point in a frame of reference of the cable-suspended platform;
(g) controlling lengths of paid-out portions of the plurality of cables in a manner that causes the cable-suspended platform to move from the first location to a second location;
(h) measuring the respective distances of the center point of the cable-suspended platform from the respective anchor points based in part on the lengths of the paid-out portions of the plurality of cables when the cable-suspended platform is at the second location;
(i) aiming the laser range meter at a second point corresponding to a second visible feature on the surface of the structure while the cable-suspended platform is at the second location and acquiring a second distance measurement;
(j) using the pan-tilt mechanism to measure the respective pan and tilt angles of the laser range meter when the laser range meter is aimed at the second point;
(k) converting the distance and angle measurements acquired in steps (i) and (j) into a second vector representing the location of the second point in the frame of reference of the cable-suspended platform;
(l) generating a transformation matrix representing a position difference and an orientation difference between the first and second locations of the cable-suspended platform based on information acquired in steps (c) and (h);
(m) multiplying the second vector by the transformation matrix to form a third vector representing the location of the second point in the frame of reference of the cable-suspended platform at the first location;
and
(n) calculating a distance between the first and second points using the first and third vectors.

12 more elements

A system for inspecting and measuring a structure comprising:

at least two anchor points;
at least two pulleys, each pulley being supported by a respective anchor point;
at least two spools;
at least two spool motors, each spool motor being operatively coupled for driving a respective spool to rotate;
at least two rotational encoders, each rotational encoder being operatively coupled to detect incremental angular movements of a respective spool;
a platform comprising a rigid support structure, a pan-tilt mechanism mounted to the rigid support structure, a camera mounted to the pan-tilt mechanism, and a laser range meter mounted to the camera;
at least two cables connected to the rigid support structure, each cable having a first portion wrapped around a respective spool and a second portion in contact with a respective pulley;
a computer system configured to control operation of the pan-tilt mechanism and the spool motors and to selectively activate the camera and laser range meter;
and
a transceiver configured to enable communication between the computer system and a control station,
wherein the computer system is further configured to:
receive image data from the camera, pan and tilt angle data from the pan-tilt mechanism, distance data from the laser range meter, and rotation data from the rotational encoders;
determine a first location of the platform relative to a structure;
and
send commands for controlling the spool motors in a manner that causes the platform to move from the first location to a second location whereat the camera is separated from a surface of the structure by a goal offset.

12 more elements

Dependencies are inferred from the claim text.

Methods for Measuring and Inspecting Structures Using Cable-Suspended Platforms

Life of this patent

Methods for Measuring and Inspecting Structures Using Cable-Suspended Platforms

Life of this patent

Abstract

Claims26