Laser Scanner Tracking via Point Cloud Center of Gravity

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Solution Overview

Problem

Conventional laser scanners lack the ability to track objects without retroreflective characteristics, relying on complex tracking optical systems and requiring retroreflective targets, which limits their functionality and flexibility.

Innovation Solution

A tracking method and laser scanner system that scans a predetermined range, acquires point cloud data, compares data cycles to detect deviations, sets a local scan area, calculates the center of gravity, and performs tracking based on this position, allowing for object tracking without the need for a tracking optical system or retroreflective targets.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a tracking optical system is provided and retroreflective targets are used, then tracking function is achieved, but device complexity increases and adaptability decreases

Engineering Contradiction:
Improvetracking functionVSAvoidoptical system complexity
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The patent extracts the tracking function from a dedicated optical tracking system and implements it through software processing of point cloud data from the existing scanning system. The tracking capability is separated from hardware complexity and achieved through algorithmic comparison of point cloud deviations, thereby eliminating the need for complex tracking optical systems while maintaining reliable tracking functionality.

Inventive Principle:
Principle #2Taking out (Extraction)

Solution Approach 2:

The patent makes the laser scanner's point cloud acquisition system perform multiple functions: both general scanning and object tracking. By processing point cloud data deviations, the same scanning hardware achieves tracking capability without requiring separate dedicated tracking optics, thus improving universality and reducing overall system complexity.

Inventive Principle:
Principle #6Universality (Multi-functionality)

2Measurement precision

If retroreflective targets are required, then tracking accuracy is improved, but ease of operation worsens due to target restrictions

Engineering Contradiction:
Improvetracking accuracyVSAvoidtarget requirement flexibility
Core Design Contradiction:
Measurement precisionVSEase of operation

Solution Approach 1:

The patent enables objects to be tracked through their own reflected light characteristics without requiring additional retroreflective markers or targets. The system extracts tracking information from the natural light reflection off the object surface, allowing the object itself to provide the necessary tracking signal, thereby eliminating the need for special retroreflective targets and improving ease of operation.

Inventive Principle:
Principle #25Self-service

3Area of stationary object

If full scan range is used for tracking, then tracking coverage is improved, but productivity decreases due to scanning inefficiency

Engineering Contradiction:
Improvetracking coverageVSAvoidscanning efficiency
Core Design Contradiction:
Area of stationary objectVSProductivity

Solution Approach 1:

The patent applies local quality by concentrating scanning resources on the local area where the target object is detected through point cloud deviation analysis. Instead of continuously scanning the entire predetermined range, the system identifies the object's position and focuses subsequent scanning on that specific local region, thereby maintaining effective tracking coverage while significantly improving scanning efficiency and productivity.

Inventive Principle:
Principle #3Local quality

Solution Approach 2:

The patent segments the scanning process into two phases: initial full-range scanning to detect object position through point cloud comparison, and subsequent localized scanning focused on the detected object. This segmentation allows the system to achieve both comprehensive tracking coverage and high scanning efficiency by dividing the scanning task into broad detection and focused tracking stages.

Inventive Principle:
Principle #1Segmentation

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

Enables simple and effective tracking of objects without the need for retroreflective characteristics, improving the flexibility and functionality of laser scanners by using a distance measuring module, optical axis deflector, and control module to detect and follow moving objects based on calculated center of gravity positions.

Implementation Method 1

a distance measuring module for irradiating a pulsed distance measuring light, receiving a reflected light, and performing the distance measurement

Methodology Applied
Scientific EffectTime of Flight: Time of Flight

Implementation Method 2

an optical axis deflector for scanning a predetermined scan range with the pulsed distance measuring light

Methodology Applied
Scientific EffectRefraction: Refraction

Implementation Method 3

the optical axis deflector has a pair of disk prisms, is configured to deflect the distance measuring light and perform a scan

Methodology Applied
Scientific EffectReflection: Reflection

Data Source

PatentEP3974775A1Tracking method, laser scanner, and tracking program
Publication Date: 2022.03.30 TOPCON CORPORATION
  • EP3974775A1 patent drawingFigure 1
  • EP3974775A1 patent drawingFigure 2
  • EP3974775A1 patent drawingFigure 3A~3B

AI summary

A laser scanner comprises a distance measuring module for performing the distance measurement, an optical axis deflector for scanning the pulsed distance measuring light, a tracking module for performing tracking, and a control module for controlling the distance measuring module, the optical axis deflector, and the tracking module. The control module detects a moving object from the point cloud data of the predetermined scan range, sets a local scan area including the object, acquires the local point cloud data of the local scan area, calculates a center of gravity position of the local point cloud data, and make the tracking module to track the object based on the calculated center of gravity position.