3D TOF Collision Avoidance With Floor-Based Self-Diagnostics
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Solution Overview
Problem
Current collision avoidance systems, particularly those using 2D laser scanners, have limitations in safety reliability and field of view, failing to meet the high safety integrity level requirements for environments needing SIL 3 with PLe performance, and lack effective diagnostic capabilities to ensure accurate distance measurements.
Innovation Solution
A 3D TOF camera system is mounted on a mobile asset at a downward incline, emitting light pulses and using a photo-sensor array to determine distance values, with self-diagnostic capabilities to verify measurement accuracy and adjust for inclination, initiating safety actions to mitigate collisions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a 2D laser scanner is used for collision avoidance, then the device complexity is reduced, but the safety reliability and field of view are insufficient to meet SIL 3 with PLe performance requirements
Solution Approach 1:
The patent transitions from 2D laser scanning to 3D time-of-flight imaging, adding a dimensional aspect to obstacle detection. The 3D camera captures depth information across a volumetric field of view, enabling comprehensive monitoring of the protective field space in front of the mobile asset, thereby achieving SIL 3 with PLe safety performance
2Reliability
If a 3D TOF camera is mounted at a downward incline to monitor ground portion, then the field of view and obstacle detection capability are improved, but the distance measurement accuracy deteriorates due to inclination effects
Solution Approach 1:
The system incorporates self-diagnostic capabilities that continuously monitor and verify distance measurements. The diagnostic component detects inclination effects and compensates for them through feedback mechanisms, ensuring measurement accuracy is maintained even when the camera is mounted at a downward incline to expand the protective field monitoring volume
Solution Approach 2:
The patent adjusts measurement parameters and calculation methods to account for the camera's inclined mounting position. By modifying how distance values are computed and interpreted based on the known inclination angle, the system maintains measurement precision while benefiting from the expanded field of view provided by the downward tilt
3Volume of stationary object
If the 3D TOF camera monitors a larger volume with downward tilt, then the protective field coverage is enhanced, but the diagnostic capability to verify measurement accuracy becomes more complex
Solution Approach 1:
The diagnostic component is integrated into the 3D TOF camera system itself, enabling self-verification of distance measurements without requiring external diagnostic equipment. The system performs self-diagnostics by analyzing the consistency of measurements across multiple pixels and time points, automatically detecting and flagging potential measurement errors while maintaining the expanded volumetric monitoring capability
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
The 3D TOF camera system enhances obstacle detection reliability, improves safety ratings by monitoring a larger volume, and ensures accurate distance measurements through diagnostic verification, effectively addressing the limitations of 2D systems.
Implementation Method 1
an emitter component configured to emit light pulses into a space in front of the mobile asset
Implementation Method 2
a photo-sensor component comprising an array of pixels, wherein respective pixels of the array of pixels are configured to convert a subset of the light pulses received from surfaces within the space to electrical energy proportional to the subset of the light pulses received at the pixels
Implementation Method 3
a distance determination component configured to: determine measured distance values dso associated with the respective pixels based on analysis of the electrical energy
Data Source
AI summary
A safety system for autonomously mobile machinery (e.g., automated guided vehicles) achieves safety-rated collision avoidance functionality by detecting objects located in the field of view of a three-dimensional (3D) time-of-flight (TOF) vision system or camera. Incorporating a 3D TOF camera into a collision avoidance system allows a large volume to be monitored for object intrusion, improving reliability of object detection. To ensure reliability of the safety system's obstacle detection capabilities, the collision avoidance system also includes self-diagnostic capabilities that verify the accuracy of the TOF camera's distance measurements even in the absence of a test object within the camera's field of view. This is achieved by tilting the TOF camera downward to include the floor within the camera's field of view, allowing the floor to act as a test object that can be leveraged to verify accuracy of the camera's distance measurements.