Interior Tracking System Using Rotating Light Beam

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Solution Overview

Problem

Existing tracking methods in interior spaces face challenges in accurately determining the position of a mobile measuring station relative to a base station, particularly due to limitations in vertical resolution and the need for precise distance measurements and image processing.

Innovation Solution

A tracking system that uses a base station to rotate a beam of light in a predetermined sequence, creating a wandering pattern of light spots on a wall, and a mobile measuring station to record images of these spots, determining the position based on image coordinates and emission directions, with distance measurements stored in a reference database.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Device complexity

If a single light beam is rotated around one axis to generate moving light points, then the device complexity is reduced, but the vertical resolution is limited and lower than horizontal resolution

Engineering Contradiction:
Improvebase station structureVSAvoidvertical resolution
Core Design Contradiction:
Device complexityVSMeasurement precision

Solution Approach 1:

The patent segments the light beam into multiple parallel light rays arranged at constant angular intervals. This segmentation allows the system to achieve vertical resolution through the different vertical angles of multiple rays while maintaining the simple single-axis rotation structure, thus resolving the contradiction between device simplicity and measurement precision.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The patent transitions from single-point tracking to multi-point tracking by using multiple parallel light rays. This dimensional expansion from one to multiple rays provides vertical resolution information that was previously unavailable, improving measurement precision without adding mechanical complexity.

Inventive Principle:
Principle #17Another dimension (Dimensionality change)

2Productivity

If the beam is rotated at high angular velocity during tracking phase, then the tracking speed and productivity are improved, but the initialization phase requires separate low-speed distance measurements

Engineering Contradiction:
Improvetracking speedVSAvoidoperation phases
Core Design Contradiction:
ProductivityVSDevice complexity

Solution Approach 1:

The patent performs distance measurements during an initialization phase before the actual tracking phase. This preliminary action stores distance information in a reference database, allowing the tracking phase to operate at high speed without performing distance measurements in real-time, thus resolving the contradiction between tracking speed and operational complexity.

Inventive Principle:
Principle #10Preliminary action

Solution Approach 2:

The patent uses periodic rotation of the light beam at different angular velocities for different phases: low speed during initialization for accurate distance measurement, and high speed during tracking for productivity. This periodic variation in operational speed optimizes both phases without requiring complex simultaneous operations.

Inventive Principle:
Principle #19Periodic action

3Measurement precision

If multiple light rays are used to improve vertical resolution, then the measurement precision is improved, but the use of energy increases

Engineering Contradiction:
Improvevertical resolutionVSAvoidlight beam energy
Core Design Contradiction:
Measurement precisionVSUse of energy by moving object

Solution Approach 1:

The patent uses a limited number of parallel light rays at constant angular intervals rather than continuously varying the beam in all directions. This partial action approach provides sufficient vertical resolution through the discrete angular separation of rays while minimizing energy consumption compared to exhaustive angular scanning.

Inventive Principle:
Principle #16Partial or excessive action

Applied Scientific Principles

This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.

Function Achieved in This Case

This method provides accurate and efficient determination of the mobile measuring station's position, improving horizontal resolution while managing the lower vertical resolution effectively, suitable for typical interior structures.

Implementation Method 1

The base station pivots or rotates a beam containing at least one light beam around at least one axis of the base station in emission directions that change according to a predetermined sequence to generate a moving pattern of light points on a wall of the interior space

Methodology Applied
Scientific EffectLight: Light

Implementation Method 2

A camera of the mobile measuring station records a series of images of the interior wall from a constant viewing direction, with at least three different image points in the series capturing one of the moving light points

Methodology Applied
Scientific EffectPhotography: Photography

Implementation Method 3

The respective distance of the axis to the wall in the measurement directions is measured based on a time-of-flight and/or interference measurement of the measuring light beam

Methodology Applied
Scientific EffectTime of flight: Time of Flight

Implementation Method 4

The respective distance of the axis to the wall in the measurement directions is measured based on a time-of-flight and/or interference measurement of the measuring light beam

Methodology Applied
Scientific EffectInterference: Interference

Data Source

PatentEP3175253B1Tracking method and tracking system
Publication Date: 2020.01.08 HILTI AG
  • EP3175253B1 patent drawingFigure 1
  • EP3175253B1 patent drawingFigure 2~3
  • EP3175253B1 patent drawingFigure 4~7

AI summary

A tracking method determines the position 55 of a mobile measuring station 6 relative to a base station 5 in an interior. The tracking system 1 has a base station 5 and a mobile measuring station 6. The position of the measuring station 6 is determined relative to the base station 5. The base station 5 swivels or rotates a beam having at least one ray of light 40 through at least one axis 29 of the base station 5, in emission directions 41 that change according to a prescribed procedure, to produce a migrating pattern of points of light 8 on a wall 3 of the interior. A camera 17 of the mobile measuring station 6 records a series of images 9 of the wall 3 of the interior in a constant line of vision 18, with one of the migrating points of light 8 being mapped in the series onto at least three different image points P1, P2, P3. The image coordinates x1, y1; x2, y2; x3, y3 of the at least three different image points P1, P2, P3 are determined. The at least three emission directions 41 of the rays of light 40 whose points of light 8 are mapped onto one of the at least three different image points P1, P2, P3 at one instant in one of the images 9 are determined on the basis of the instants at which the respective image 9 is recorded. The at least three distances d1, d2, d3 of the axis 29 of the base station 5 from the wall 3 in the at least three emission directions 41 are ascertained on the basis of distance measurements, stored in a reference database 52, from the wall 3 in directions of measurement 44 from the base station 5. The position 55 of the mobile measuring station 6 is ascertained on the basis of the image coordinates x1, y1; x2, y2; x3, y3 of the at least three image points P1, P2, P3, the emission directions 41 associated with the image points P1, P2, P3 and the respective distances d1, d2, d3 of the base station 5 from the wall 3 in the associated emission directions 41.