Multi-Head Laser Tracking for Precise Robot Orientation
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Solution Overview
Problem
Current laser tracking systems for robots face challenges in accurately tracking the position and orientation of robot components in real-time, especially at longer distances, due to line-of-sight issues and high positional errors, which result in vibrations and reduced accuracy for fine positioning tasks.
Innovation Solution
A tracking system with multiple tracking heads and targets, where each tracking head has a radiation source, sensor, and actuator, and targets with reflectors, allows for continuous tracking and accurate determination of position and orientation by using signals from base sensors and angle sensors, transforming data into a common coordinate system, and maintaining line of sight through adjustable mounts.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a single tracking head is used to measure position and orientation, then the device complexity is reduced, but the measurement precision deteriorates due to inability to calculate orientation mathematically
Solution Approach 1:
The system divides the measurement function into two separate components: position measurement (performed by the tracking head using laser time-of-flight) and orientation measurement (performed by calculating the relative positions of multiple targets). This segmentation allows each component to be optimized independently, achieving high precision without excessive complexity.
Solution Approach 2:
The system replaces the mechanical orientation sensing mechanism (physical orientation sensors on the tracking head) with a mathematical calculation approach. By measuring the positions of multiple targets and computing their relative geometry, the system derives orientation information without requiring the tracking head to physically sense orientation, thereby improving precision while maintaining manageable complexity.
2Measurement precision
If the end effector is positioned far from the tracking target, then the ease of operation is improved, but the measurement precision deteriorates due to greater positional error
Solution Approach 1:
The system replaces direct mechanical measurement of end effector position with an indirect mathematical approach. By measuring the positions of multiple targets attached to the end effector and calculating their relative geometry, the system derives end effector position and orientation with high precision regardless of the distance between the tracking target and end effector, eliminating the error amplification problem.
Solution Approach 2:
The system transitions from measuring a single point (tracking target position) to measuring multiple points in space (multiple targets on the end effector). By utilizing the spatial relationships between multiple targets in three-dimensional space, the system can accurately determine both position and orientation, providing high precision while allowing flexible target placement.
3Productivity
If orientation measurements are taken at low frequency (100 Hz), then the device complexity is reduced, but the productivity deteriorates due to inability to perform dynamic measurements
Solution Approach 1:
The system separates position measurement (which can be performed at high frequency using laser time-of-flight) from orientation measurement (which is calculated from position data). This allows position to be measured at high sampling rates for dynamic applications, while orientation is derived through mathematical computation, achieving high productivity without requiring complex high-frequency orientation sensing hardware.
4Measurement precision
If a single target is used for tracking, then the device complexity is reduced, but the measurement precision deteriorates due to inability to determine orientation
Solution Approach 1:
The multiple targets serve dual functions: they enable orientation determination through their relative geometric arrangement, and they provide redundant position measurement points that improve overall measurement precision. Each target acts as both a position reference and an orientation reference, maximizing the utility of each additional target while achieving high measurement accuracy.
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 system provides improved positional accuracy and reduced vibration, enabling precise tracking and orientation measurements with lower latency, suitable for dynamic and fine positioning tasks like brick laying, by using multiple tracking heads and targets to calculate orientation mathematically and maintain line of sight.
Implementation Method 1
a radiation source arranged to send a radiation beam to a respective target; a base sensor that senses reflected radiation
Data Source
AI summary
The present disclosure relates to a tracking system for tracking a position and orientation of an object, the tracking system including: a tracking base provided in an environment, the tracking base including: a tracking head support; and, at least three tracking heads mounted to the tracking head support, a target system including at least three targets mounted to the object, each target including a reflector that reflects a radiation beam to the base sensor of a respective tracking head; and, a control system that: causes each tracking head to track a respective target as it moves throughout the environment; determines a position of each target with respect to a respective tracking head; determines an orientation of the target system using at least in part the determined position of each target; and, determines the position and orientation of the object using at least in part the position and orientation of the target system.