Adaptive Laser Power for Time-of-Flight Sensor Safety and Range
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Solution Overview
Problem
Conventional time of flight (TOF) sensors face challenges in accurately detecting objects at close ranges due to non-linear and imprecise range detection results, and they often operate with fixed laser output power levels that are not safe for all operating ranges.
Innovation Solution
The proposed solution involves dynamically adapting the output power level of a laser in a TOF range detection device. The device initially operates at a mid-level output power and adjusts to higher or lower power levels based on the presence and distance of objects, ensuring safety and accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Length of stationary object
If a high powered laser is used to detect objects at far distances, then the ranging range is improved, but the safety is worsened for mid- or near-range operation
Solution Approach 1:
The laser output power is made dynamically adjustable rather than fixed. The system transitions from a static high-power configuration to a dynamic system that adapts power levels based on detected object distance, allowing safe operation at near ranges while maintaining far-range capability when needed.
Solution Approach 2:
The system changes the laser power parameter adaptively based on operating conditions. By monitoring the detected object distance and adjusting the laser power accordingly, the system resolves the contradiction between achieving long ranging range and maintaining safety at closer distances.
2Object-affected harmful factors
If a fixed low power laser is used for safety at near ranges, then the safety is improved, but the ranging range and detection accuracy are worsened for far distances
Solution Approach 1:
The system dynamically adjusts laser power based on detected object distance, transitioning from low power at near ranges to high power at far ranges. This dynamic adaptation allows the system to achieve both safety and extended ranging capability, resolving the limitation of fixed low-power lasers.
Solution Approach 2:
The laser power parameter is changed adaptively based on the operating scenario. The system increases power when far-range detection is required and reduces power when safety is prioritized at closer distances, thereby achieving both safety and extended range capabilities.
3Length of stationary object
If high power laser is used to increase ranging limit, then the detection range is improved, but the power consumption is worsened
Solution Approach 1:
The system dynamically adjusts laser power based on actual detection needs. By using higher power only when and where necessary (i.e., when detecting far-range objects), the system achieves extended detection range while minimizing overall power consumption compared to continuous high-power operation.
Solution Approach 2:
The laser power parameter is adaptively changed based on the detected object distance and detection requirements. The system increases power consumption only when far-range detection is needed, thereby achieving extended detection range while optimizing power consumption for the actual operational requirements.
4Object-affected harmful factors
If mid-level power is used initially for safety, then the safety is improved, but the detection accuracy at close ranges is worsened due to non-linear detection
Solution Approach 1:
The system dynamically adjusts laser power based on detected object distance. When objects are detected at close ranges, the system switches to low power mode to eliminate non-linear detection effects and improve measurement precision, while maintaining safety through adaptive power control.
Solution Approach 2:
The laser power parameter is changed based on the operating condition and detected object distance. By reducing power when close-range detection is required, the system eliminates non-linear detection artifacts and improves measurement precision while maintaining safety through adaptive power adjustment.
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 adaptive power control allows for accurate detection of objects at various ranges, improves safety by operating within safe laser classification limits, and reduces power consumption by adjusting output power according to detected distances.
Implementation Method 1
time of flight range detection device
Implementation Method 2
a laser that operably transmits an optical pulse
Implementation Method 3
an optical barrier configured to reflect a first portion of the transmitted optical pulse
Implementation Method 4
a reference single-photon avalanche diode (SPAD) array configured to receive the first portion of the optical pulse reflected by the optical barrier
Data Source
AI summary
A time of flight range detection device includes a laser configured to transmit an optical pulse into an image scene, a return single-photon avalanche diode (SPAD) array, a reference SPAD array, a range detection circuit coupled to the return SPAD array and the reference SPAD array, and a laser driver circuit. The range detection circuit in operation determines a distance to an object based on signals from the return SPAD array and the reference SPAD array. The laser driver circuit in operation varies an output power level of the laser in response to the determined distance to the object.