Multi-Channel Distance Module With External Signal Shifting
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Solution Overview
Problem
Existing multi-channel distance measuring modules, particularly those using integrated circuits, face limitations in addressing periodic or cyclic errors and are susceptible to parasitic effects, leading to reduced accuracy and increased power consumption.
Innovation Solution
A multi-channel distance measuring module with a signal shifting unit external to the sensor unit, which alters the emission instants relative to the sampling clock using a non-integer multiplier offset, combined with a flexible clocking system to reduce cyclic errors and parasitic effects, allowing for increased accuracy without substantial power increase.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the sampling clock frequency is increased to reduce the time interval between samples, then the measurement precision is improved, but the periodic or cyclic error becomes a dominant source of error due to the exact time difference between sampling instants and photon arrival times
Solution Approach 1:
The patent applies preliminary action by pre-calculating and storing correction values for periodic errors in a lookup table before measurement. The system determines the time difference between the sampling clock edge and the expected photon arrival time, then retrieves the corresponding correction value to compensate for the systematic error, rather than attempting to eliminate the error through higher sampling frequencies alone.
Solution Approach 2:
The patent changes the parameter of sampling timing by introducing a variable offset between the sampling clock edge and the photon arrival time. By adjusting the sampling phase and applying time-dependent correction values, the system transforms the fixed periodic error into a correctable variable, allowing accurate measurement without requiring excessively high sampling frequencies.
2Device complexity
If conventional distance measurement methods are used without signal shifting, then the device complexity is low, but the susceptibility to parasitic effects and cyclic errors increases
Solution Approach 1:
The patent introduces an intermediary signal shifting unit that sits between the sensor unit and the distance calculation unit. This intermediary component shifts the emission instants relative to the sampling clock by a non-integer multiple of the clock period, thereby decoupling the measurement process from the periodic parasitic effects of the sampling clock while adding minimal complexity to the overall system.
3Measurement precision
If the sampling frequency is increased to improve time resolution, then the measurement precision is improved, but the power consumption increases substantially
Solution Approach 1:
The patent applies partial action by using a moderate sampling frequency that is not excessively high, combined with a correction mechanism that provides the equivalent precision benefit of a much higher frequency. The signal shifting unit introduces a non-integer offset that effectively increases the time resolution without requiring the sampling clock to run at proportionally higher speeds, thus avoiding the quadratic power consumption increase that would otherwise be necessary.
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 solution effectively reduces cyclic errors and susceptibility to parasitic effects, enhancing measurement accuracy and flexibility while maintaining power efficiency.
Implementation Method 1
The distance is measured based on a parameter associated with the time-of-flight of a measurement signal emitted by the distance measuring module and returning from the environment
Implementation Method 2
Each of the SPAD elements is designed for the purpose of being able to detect an arrival time of individual photons (or individual photon packages) correctly
Data Source
AI summary
Embodiments of the present disclosure relate to a multi-channel distance measuring module for providing scanning of an environment. The distance measuring module comprises an emitter for emitting emission signals and a sensor unit embodied as integrated circuit, which comprises a multi-channel receiver with a detection surface comprising multiple detection elements arranged as a matrix structure on a chip, and a trigger unit configured to generate a sensor output trigger signal that provides trigger times defined by the sensor unit. Each of the multiple channels of the receiver is provided by a macro-pixel formed by a subset of the detection elements associated to the detection channel. The distance measuring module further comprises a signal shifting unit external to the sensor unit for altering the time positioning of actual emission instants by the emitter relative to a sampling clock of the sensor unit.