Hybrid TOF-Triangulation Range Sensor for Near-Far 3D Sensing
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Solution Overview
Problem
Existing 3D imaging technologies face challenges in accurately determining the range of objects under difficult conditions such as low light, bad weather, and strong ambient light, particularly in distinguishing between distant and near objects effectively.
Innovation Solution
A range sensor system that combines direct time-of-flight (TOF) and triangulation methods within a single image sensor, using a light source to project a sheet of light at an angle, an offset image sensor, and collection optics to determine object ranges, with the option to ignore certain ranges through range gating and employing a single photon avalanche diode (SPAD) array in both avalanche and linear modes to reduce power consumption and interference.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Length of stationary object
If direct time-of-flight method is used for distant objects, then measurement range is extended, but measurement precision deteriorates for near objects
Solution Approach 1:
The patent divides the measurement space into two segments: distant objects measured by direct time-of-flight method and near objects measured by triangulation method. This segmentation allows each method to operate in its optimal range, resolving the contradiction between extended measurement range and maintained precision.
Solution Approach 2:
The system dynamically switches between direct time-of-flight and triangulation methods based on object distance. The controller selects the appropriate measurement method for each object, enabling the system to adaptively maintain high precision across varying ranges.
2Measurement precision
If triangulation method is used for near objects, then measurement precision is improved, but device complexity increases
Solution Approach 1:
The patent merges direct time-of-flight and triangulation methods into a single integrated range sensor system. By combining both methods in one device with a unified controller, the system achieves high precision for near objects without proportionally increasing overall device complexity.
Solution Approach 2:
The range sensor system is designed to perform multiple functions: direct time-of-flight measurement for distant objects and triangulation measurement for near objects. This multi-functionality allows a single device to handle diverse measurement scenarios without requiring separate dedicated systems.
3Reliability
If SPAD array operates in avalanche mode for high sensitivity, then detection capability is enhanced, but power consumption increases
Solution Approach 1:
The SPAD array dynamically switches between avalanche mode and linear mode based on measurement requirements. Avalanche mode is activated when high sensitivity is needed for distant or low-light objects, while linear mode is used for near objects or brighter conditions, thereby reducing overall power consumption while maintaining detection capability when needed.
4Measurement precision
If range gating is applied to ignore certain ranges, then measurement accuracy is improved, but loss of information occurs
Solution Approach 1:
Range gating segments the measurement ranges by ignoring only those ranges where neither direct time-of-flight nor triangulation methods are applicable. This selective gating reduces noise and improves accuracy for measurable objects while preserving information about objects within the valid measurement ranges.
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 approach enhances the accuracy and efficiency of range determination for both distant and near objects, improves performance under challenging conditions, and reduces power consumption and substrate-induced interference, thereby improving the reliability of 3D imaging systems.
Implementation Method 1
range (or distance) to a 3D object is resolved based on the known speed of light, by measuring the round-trip time it takes for a light signal to travel between a camera and the 3D object
Implementation Method 2
using a single photon avalanche diode (SPAD) array in both an avalanche mode and a linear mode
Data Source
AI summary
A range sensor and a method thereof. The range sensor includes a light source configured to project a sheet of light at an angle within a field of view (FOV); an image sensor offset from the light source; collection optics; and a controller connected to the light source, the image sensor, and the collection optics, and configured to determine a range of a distant object based on direct time-of-flight and determine a range of a near object based on triangulation. The method includes projecting, by a light source, a sheet of light at an angle within an FOV; offsetting an image sensor from the light source; collecting, by collection optics, the sheet of light reflected off objects; and determining, by a controller connected to the light source, the image sensor, and the collection optics, a range of a distant object based on direct time-of-flight and a range of a near object based on triangulation simultaneously.