Phase Modulation Runtime Measurement for 3D Lidar
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Solution Overview
Problem
Current 3D lidar sensors for distance measurement are complex, expensive, and require high computational effort, with limitations in accuracy and mobility due to the need for high sampling rates and complex signal processing, making them unsuitable for mobile or battery-operated applications.
Innovation Solution
A method and arrangement for runtime measurement using a modulation signal with digitally determined phase positions for the transmission and reception of pulses, allowing for accurate distance calculation with reduced computational effort by storing and comparing sampled value patterns, eliminating the need for high-frequency sampling and complex circuitry.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If direct time of flight method with high sampling rate is used for distance measurement, then measurement precision is improved, but device complexity and power consumption increase
Solution Approach 1:
The patent replaces complex high-speed electronic timing circuits with a phase modulation approach. Instead of directly measuring time of flight with high-frequency clocks, the system modulates the light source with a periodic signal and measures phase shift, substituting mechanical/electronic timing with optical modulation and correlation detection.
Solution Approach 2:
The patent introduces a periodic modulation signal as an intermediary between the light source and the detection process. This modulation signal serves as a reference that enables correlation-based measurement, simplifying the direct time measurement problem into a phase comparison problem that can be solved with lower-frequency electronics.
2Measurement precision
If complex signal processing methods with very high sampling rates are used, then measurement precision is improved, but use of energy increases
Solution Approach 1:
The patent employs periodic modulation of the light source intensity at a specific frequency. This periodic action creates a reference signal that can be correlated with the received signal, enabling precise measurement without requiring continuous high-speed sampling. The system only needs to sample at the modulation frequency, dramatically reducing power consumption.
Solution Approach 2:
The patent changes the measurement parameter from direct time measurement to phase shift measurement. By measuring the phase difference between transmitted and received modulated signals, the system achieves high precision with lower sampling rates, as phase can be determined with much coarser temporal resolution than direct time-of-flight measurement.
3Measurement precision
If phase shift method with high modulation frequency is used, then measurement precision is improved, but device complexity increases
Solution Approach 1:
The patent implements a correlation-based measurement approach that can determine both distance and velocity using the same hardware setup. The periodic modulation and correlation detection framework is universal, handling various measurement scenarios without requiring additional specialized circuits, thereby reducing overall device complexity.
4Adaptability or versatility
If direct time of flight method is used for large distances, then adaptability is improved, but measurement precision deteriorates
Solution Approach 1:
The patent implements a dynamic measurement approach where the system can adapt its modulation frequency and correlation window based on the expected distance range. For longer distances, the system uses lower modulation frequencies and extended correlation windows, while for shorter distances it can use higher frequencies for improved precision, making the system adaptable across wide distance 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 enables precise and inexpensive 3D lidar sensors with reduced power consumption and flexibility, suitable for various applications, including autonomous vehicles and indoor smart sensing, with the ability to self-calibrate and avoid high-frequency signal processing, resulting in cost-effective and efficient distance measurement systems.
Implementation Method 1
a transmitter (1) transmits a pulse (2) of a physical signal in a transfer medium; a sensor receives a reflection (4) of the pulse
Implementation Method 2
a sensor receives a reflection (4) of the pulse
Implementation Method 3
a phase shift between the signal on the occurrence of a first event and the signal on the occurrence of a second event is determined; the phase position of the modulation signal is determined as a first signature for the occurrence of the signal in the first event and as a second signature for the occurrence of the signal in the second event
Data Source
AI summary
Method for a runtime measurement of a signal between two events. A phase shift between the signal on the occurrence of a first event and the signal on the occurrence of a second event is determined, and to an arrangement for performing the method has the underlying object of providing a runtime measurement of a signal between a first event and a second event that can be carried out with a high accuracy, at a high speed, and with a low computational effort. A modulation signal is generated whose phase position is determined as a first signature for the occurrence of the signal in the first event. The phase position of the modulation signal is determined as a second signature for the occurrence of the signal in the second event; and in that the runtime is determined as a difference of the phase positions of the first and second signatures.