Laser Tracker Roll Angle Measurement via Parallel Beams
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Solution Overview
Problem
Current laser tracking systems face challenges in achieving accurate and real-time roll angle measurement, leading to delays and reduced accuracy in dynamic motion compensation for industrial and construction robots, especially under outdoor conditions with dynamic movement and environmental factors.
Innovation Solution
A tracking system that uses a bidirectional light beam and a unidirectional light beam parallel to it, with an optical mount for controlled rotation to maintain linkage and determine roll angle, employing a position displacement sensor for precise roll angle measurement, enabling continuous and accurate roll angle data at high frequencies.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If vision systems using 2D cameras are used to measure orientation, then the system can measure position and orientation, but the measurement frequency is limited to a maximum of 100 Hz causing delays in real-time control
Solution Approach 1:
The patent replaces the mechanical vision system (2D cameras requiring complex image processing) with an optical sensing system using position sensors that directly detect laser beam positions. This substitution enables measurement at 1kHz frequency while maintaining orientation measurement accuracy, resolving the contradiction between measurement precision and productivity.
2Adaptability or versatility
If the laser tracker shifts lock between multiple Tmac frames to achieve greater field of view, then the field of view is increased, but data loss occurs during the shift causing interruptions in continuous measurement
Solution Approach 1:
The patent segments the field of view coverage by deploying multiple laser trackers with overlapping fields of view. Each tracker maintains continuous lock on its designated target without shifting, and the system integrates data from all trackers. This segmentation approach increases the overall field of view while maintaining measurement continuity, resolving the contradiction between adaptability and reliability.
3Productivity
If accelerometer data from tilt sensor or INS is used to determine orientation, then the measurement frequency can reach up to 1000 Hz, but the orientation accuracy is reduced to 0.01 degree
Solution Approach 1:
The patent merges two measurement approaches: using laser-based position sensors for high-accuracy orientation measurement (0.001 degree) at 1kHz frequency, and combining this with accelerometer data from INS for dynamic motion compensation. The integrated system achieves both high measurement frequency and high orientation accuracy, resolving the contradiction between productivity and measurement precision.
4Device complexity
If a single Tmac frame is used, then the system is simple, but the field of view is limited to approximately 90 degrees requiring multiple frames for broader coverage
Solution Approach 1:
The patent makes the laser tracker system universal by enabling each tracker to serve multiple functions: measuring position, orientation (pitch and yaw), and working with multiple targets within its field of view. The system can dynamically assign different targets to different trackers, providing adaptable field of view coverage without requiring complex mechanical reconfiguration, resolving the contradiction between device complexity and adaptability.
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 solution provides roll angle accuracy of up to 0.001 degrees at 1kHz, enhancing the absolute position accuracy of robotic end effectors to 0.2mm within a 40m radius, reducing latency and noise, and enabling effective dynamic motion compensation.
Implementation Method 1
a sensor housed in at least one of the tracking base and the tracking target that detects the unidirectional light beam
Data Source
Figure 1A
Figure 1B
Figure 1C~1D
AI summary
The present disclosure relates to a tracking system for tracking the position and orientation of an object in an environment, the tracking system including: (a) a tracking base positioned in the environment; (b) a tracking target mountable to the object, wherein in use the tracking base is linked to the tracking target by: (i) a bidirectional light beam transmitted therebetween; and, (ii) a unidirectional light beam transmitted therebetween, said unidirectional light beam parallel to the bidirectional light beam; and, (c) at least one controller configured to determine a roll angle of the tracking target relative to the tracking base, the roll angle determined at least in part by signals received from a sensor housed in at least one of the tracking base and the tracking target that detects the unidirectional light beam.