Laser TOF Sensor Misalignment Compensation via Timing Correction
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Solution Overview
Problem
Current laser-based distance measurement systems face inaccuracies due to measurement errors and limitations in pulse spacing, which can result in incorrect distance calculations, especially when multiple laser light sources are not perfectly aligned, leading to misaligned projection regions and skewed depth data.
Innovation Solution
The system employs multiple laser light sources of different wavelengths with a scanning mirror and timing correction mechanisms to achieve alignment by adjusting the relative timing of transmitted light pulses and reordering the sequence of reflected results, ensuring consistent spatial mapping across the intended scan region, thereby reducing vertical and horizontal offsets between projection regions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If multiple laser light sources are used to increase measurement coverage, then productivity is improved, but manufacturing precision deteriorates due to misalignment between projection regions
Solution Approach 1:
The system performs preliminary characterization of each laser light source's projection region and applies timing offsets before actual depth mapping to pre-correct for misalignments. This allows multiple laser sources to be used simultaneously without compromising spatial accuracy.
Solution Approach 2:
The system changes the timing parameter of laser pulse emission by applying specific offsets to different laser light sources. This temporal parameter adjustment compensates for spatial misalignments in projection regions, enabling accurate depth mapping with multiple sources.
2Productivity
If laser pulses are emitted closer together in time to increase scanning speed, then productivity is improved, but measurement precision deteriorates due to pulse corruption from overlapping return signals
Solution Approach 1:
The system characterizes the time-of-flight and pulse spacing requirements before initiating the scanning sequence, allowing optimal pulse timing to be predetermined. This ensures that pulses are spaced sufficiently to avoid corruption while maintaining high scanning speed.
Solution Approach 2:
The system uses periodic laser pulse emission with carefully controlled spacing between pulses. By maintaining regular intervals that exceed the maximum time-of-flight, the system achieves high-speed scanning while preventing signal overlap and measurement corruption.
3Manufacturing precision
If timing correction mechanisms are applied to correct misalignment, then manufacturing precision is improved, but device complexity increases
Solution Approach 1:
The system replaces complex mechanical alignment mechanisms with electronic timing corrections. Instead of physically adjusting laser source positions, the system uses software-based timing offsets to achieve precise spatial mapping, significantly reducing mechanical complexity.
Solution Approach 2:
The system adjusts temporal parameters (timing offsets) rather than spatial parameters (physical positions) to correct misalignments. This parameter transformation from spatial to temporal domain simplifies the correction mechanism while maintaining high precision.
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 spatial resolution and accuracy of distance measurements by ensuring that laser pulses from different sources are directed to the same points in space, resulting in a consistent spatial map and improved horizontal spatial resolution, even in the presence of initial misalignments.
Implementation Method 1
The round trip time-of-flight (TOF) of the outgoing laser pulse 112 and return laser pulse 114 is measured by rangefinder 110 to determine the distance between rangefinder 110 and target 140.
Data Source
AI summary
Laser light pulses of at least two different wavelengths are reflected off a scanning mirror. A first time-of-flight distance measurement circuit receives reflected light pulses of a first wavelength and determines distances. A second time-of-flight distance measurement circuit receives reflected light pulses of a second wavelength and determines distances. The timing of transmission of laser light pulses of differing wavelengths are adjusted, and the data buffering of converted return pulses are adjusted, to compensate for laser light source misalignment.