Active Target Tracking for Precise 2D Position Measurement

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Solution Overview

Problem

Current surveying systems face challenges in accurately determining the positioning of a dipstick on a survey point without causing measurement errors due to wobbly equipment or premature triggering, and they require synchronized clocks for precise alignment.

Innovation Solution

A control method for a surveying system that involves emitting a light beam from a base station, rotating its direction using rotatable optics, detecting the impact point on a dipstick with a spatially resolving light sensor, determining a distance vector, and aligning the beam with a reference point on the dipstick, allowing the user to confirm correct positioning before measuring the emission direction with an angle encoder.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If the light beam is rotated to search for the sounding rod, then the surveying system can locate the rod, but measurement errors occur due to wobbly equipment or premature triggering

Engineering Contradiction:
Improvepositioning accuracyVSAvoidmeasurement error
Core Design Contradiction:
Measurement precisionVSReliability

Solution Approach 1:

The system performs preliminary alignment by rotating the light beam to search for the sounding rod and detect the reference point before final measurement. The evaluation unit determines when the light beam has correctly hit the reference point, and only then is the emission direction measured and recorded. This preliminary searching and alignment action ensures that measurements are only taken when proper alignment is achieved, eliminating premature triggering errors.

Inventive Principle:
Principle #10Preliminary action

2Measurement precision

If synchronized clocks are used for precise alignment, then the emission direction can be accurately determined, but the system complexity increases

Engineering Contradiction:
Improveemission direction determinationVSAvoidsynchronized clocks requirement
Core Design Contradiction:
Measurement precisionVSDevice complexity

Solution Approach 1:

The sounding rod serves itself by detecting when the light beam hits its reference point and generating the trigger signal for measurement. The evaluation unit in the sounding rod autonomously determines alignment by analyzing the light beam's position on the light sensor, eliminating the need for external synchronized clocks between the base station and sounding rod. The system uses the sounding rod's own detection capability to control the measurement timing.

Inventive Principle:
Principle #25Self-service

3Adaptability or versatility

If the light beam is continuously rotated, then the surveying system can cover all directions, but the determination of emission direction is delayed until the point of impact rests on the reference point

Engineering Contradiction:
Improvedirectional coverageVSAvoidmeasurement delay
Core Design Contradiction:
Adaptability or versatilityVSLoss of time

Solution Approach 1:

The light beam is rotated periodically to sweep through all directions and search for the sounding rod. The rotation continues until the evaluation unit detects that the light beam has hit the reference point, at which moment the periodic rotation stops and the emission direction is immediately measured and recorded. This periodic scanning approach ensures complete directional coverage while minimizing delay by stopping the rotation exactly when the target is found.

Inventive Principle:
Principle #19Periodic 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 ensures accurate alignment by eliminating measurement errors caused by wobbly equipment and removes the need for synchronized clocks, allowing for precise determination of survey points without relative movement of the light beam.

Implementation Method 1

Emitting a light beam by a light source in the base station; rotating the emission direction of the light beam about an axis by means of a rotatable optic of the base station

Methodology Applied
Scientific EffectLight: Light

Implementation Method 2

detecting a deviation of the point of impact of the light beam on a spatially resolving light sensor of the sounding rod

Methodology Applied
Scientific EffectPhotoelectric Effect: Photoelectric Effect

Data Source

PatentEP3615888B12d position measuring system based on the tracking of active targets
Publication Date: 2021.12.29 HILTI AG
  • EP3615888B1 patent drawingFigure 1~2
  • EP3615888B1 patent drawingFigure 3~4

AI summary

A control method is provided for a measuring system (1) comprising a marker rod (3) and a base station (2). The control method has the following steps: emitting a light beam (5) by means of a light source (7) in the base station (2); rotating the emission direction (6) of the light beam (5) about an axis (4) by means of a rotatable optical system (8) of the base station (2); aligning the light beam (5) onto the marker rod (3); confirming the position of the marker rod (3) on a measurement point P by means of a user; determining the emission direction (6) of the light beam (5) using an angle encoder (17) in the base station (2), wherein the determination of the emission direction (6) is delayed until the emission direction (6) is aligned; and recording the determined emission direction (6) belonging to the measurement point P by means of a logging device (36).