Markerless 6DOF Tracking via Modulated Laser and IMU Fusion
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Solution Overview
Problem
Current positional tracking systems in construction jobsites face challenges in using multiple independent laser receivers to simultaneously calculate positions without communication with the laser transmitter, and existing algorithms are not robust enough to handle environments with transparent, shiny, or textureless objects, requiring large tracking markers and being computationally expensive.
Innovation Solution
A positional tracking system that includes a laser transmitter, control tracker, and layout indicator, utilizing photo diodes and inertial measurement units to calculate 6DOF positions of objects without markers, using modulated laser beams and camera vision to determine object orientation and location, allowing multiple users to simultaneously track positions and orientations of objects with high accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If traditional laser measuring systems are used with one laser receiver, then measurement accuracy is maintained, but productivity is reduced due to sequential position measurement
Solution Approach 1:
The system divides the measurement task by deploying multiple independent laser receivers simultaneously across different locations, allowing parallel position measurements instead of sequential measurement by a single receiver
Solution Approach 2:
Each laser receiver is equipped with both camera and IMU capabilities, allowing it to perform multiple functions (visual feature detection, inertial tracking, laser beam detection) simultaneously, enabling robust 6DOF tracking without requiring large markers
2Productivity
If multiple independent laser receivers are deployed simultaneously, then productivity is improved, but coordination complexity increases without communication with the laser transmitter
Solution Approach 1:
Each laser receiver independently detects the modulated laser beam and extracts position information without requiring communication or coordination with the laser transmitter, eliminating system complexity while enabling simultaneous operation of multiple receivers
Solution Approach 2:
The laser transmitter emits modulated laser beams at periodic intervals, allowing each receiver to independently detect and process signals without requiring inter-device communication or synchronization protocols
3Device complexity
If natural image features are used for tracking, then marker requirements are eliminated, but tracking reliability decreases in construction environments with transparent, shiny, or textureless objects
Solution Approach 1:
The system merges multiple tracking approaches by combining natural feature detection with inertial measurement unit (IMU) data and laser beam detection, creating a hybrid system that maintains reliability in challenging construction environments without requiring artificial markers
Solution Approach 2:
The tracking system uses a composite approach combining visual features, inertial sensors, and optical laser detection to create a robust multi-sensor system that overcomes the limitations of any single method in transparent, shiny, or textureless environments
4Device complexity
If natural image features are extracted and identified, then marker-based tracking is eliminated, but computational cost increases
Solution Approach 1:
The system uses partial action by leveraging the laser beam itself as a reference feature that simplifies feature extraction and matching computations, reducing the computational burden compared to extracting and tracking all natural features in the scene
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 simultaneous, accurate calculation of positions and orientations of multiple objects with six degrees of freedom, reducing the need for manual placement of laser receivers and improving tracking precision in diverse construction environments, allowing multiple users to work efficiently by correlating building information models with physical jobsite locations.
Implementation Method 1
a laser transmitter 110, a control tracker 200, a layout indicator 300
Implementation Method 2
utilizing photo diodes and inertial measurement units to calculate 6DOF positions
Implementation Method 3
The laser beam may impinge directly on the point or may impinge on a retro reflector target that is contact with the point
Implementation Method 4
utilizing photo diodes and inertial measurement units to calculate 6DOF positions of objects
Data Source
AI summary
A position tracking system has a laser transmitter, a control tracker and a layout indicator. The laser transmitter has a laser for emitting a laser beam, a controller controlling the laser, and a motor for rotating the emitted laser beam. The control tracker has a housing, at least two photo diodes disposed on the housing, and a laser assembly for generating a beam to be projected unto a surface. The layout indicator has a housing, and at least two photo diodes disposed on the housing. A network server communicates with at least one of the laser transmitter, the control tracker and the layout indicator.