ToF LIDAR Frequency Toggling for Extended Unambiguous Range
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Solution Overview
Problem
Existing LIDAR systems face challenges in accurately determining distance to targets due to unambiguous range rollover errors and limited precision without increasing processing time or physical resources.
Innovation Solution
Employing alternating combinations of scanning frequencies in a LIDAR system to calculate true distances by toggling modulation frequencies in subsets of frames, allowing for extended unambiguous range without increasing error rates.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a single modulation frequency is used in ToF LIDAR systems, then the system operation is simple, but the unambiguous range is limited and distance measurement precision deteriorates
Solution Approach 1:
The patent applies periodic action by alternating between multiple modulation frequencies in a periodic manner. The system toggles between a first modulation frequency and a second modulation frequency across different subframes, allowing the system to accumulate distance measurement data at multiple frequencies over time. This periodic frequency switching enables extended unambiguous range and improved distance precision without requiring simultaneous multi-frequency processing, thus maintaining operational simplicity while achieving higher measurement accuracy.
Solution Approach 2:
The patent implements parameter changes by dynamically switching the modulation frequency parameter between at least two different values. By changing the modulation frequency from a first frequency to a second frequency across different subframes, the system extends the unambiguous range (which is directly proportional to the modulation frequency) and improves distance measurement precision. The controller manages these parameter changes systematically, combining the measurements to achieve accurate distance determination beyond the limitations of any single frequency.
2Measurement precision
If multiple modulation frequencies are used simultaneously, then the unambiguous range is extended, but the processing time and computational resources increase
Solution Approach 1:
The system uses periodic action by sequentially alternating between multiple modulation frequencies across different subframes rather than processing multiple frequencies simultaneously. The controller toggles the modulation frequency in a periodic pattern, collecting measurement data at each frequency over time. This approach extends the effective unambiguous range by combining measurements from multiple frequencies while avoiding the computational overhead of simultaneous multi-frequency processing, thus reducing processing time and resource requirements.
Solution Approach 2:
The patent applies segmentation by dividing the measurement process into separate subframes, each dedicated to a specific modulation frequency. Instead of handling multiple frequencies at once, the system segments the acquisition process temporally, collecting data at the first frequency in one subframe, then switching to the second frequency in another subframe. This segmentation allows for simpler per-subframe processing while achieving extended unambiguous range through combination of segmented measurements, thereby reducing overall processing complexity and time.
3Length of stationary object
If the unambiguous range is extended by using lower modulation frequencies, then the measurement range increases, but the distance measurement precision decreases
Solution Approach 1:
The patent implements parameter changes by switching between multiple modulation frequency values to optimize the trade-off between unambiguous range and measurement precision. When measurement precision is critical, the system uses higher modulation frequencies that provide finer distance resolution. When extended range is needed, it switches to lower modulation frequencies that provide larger unambiguous range. By dynamically changing the frequency parameter and systematically combining measurements from multiple frequencies, the system achieves both extended range and maintained precision that would be impossible with any single frequency.
Solution Approach 2:
The system applies periodic action by alternately using higher and lower modulation frequencies across different subframes. This periodic switching allows the system to collect high-precision measurements at higher frequencies and range-extending measurements at lower frequencies, then combine them periodically to achieve both extended unambiguous range and high distance measurement precision. The periodic alternation ensures that neither extreme is used exclusively, thereby resolving the trade-off between range and 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
Enhances distance measurement precision and extends unambiguous range in LIDAR systems while maintaining efficiency and reducing power consumption.
Implementation Method 1
a laser diode, such as a VCSEL or other surface-emitting laser diode, an edge-emitting laser diode, and/or other semiconductor laser
Implementation Method 2
Direct ToF measurement includes directly measuring the length of time between emitting radiation by an emitter element of a ToF system, and sensing the radiation after reflection from an object or other target
Data Source
Figure 1~2
Figure 3~4
Figure 5A~5B
AI summary
A method of operating a time of flight system includes detecting first optical signals comprising a first frequency having a first unambiguous range, the first optical signals reflected from a target, processing the first optical signals to determine a first estimated distance to the target, and generating an output frame comprising a true distance to the target based on the first estimated distance and a second estimated distance to the target, wherein the second estimated distance was used to generate a previous output frame.