Configurable Phase Delay Time-of-Flight Sensor
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Solution Overview
Problem
Traditional time-of-flight (ToF) cameras face errors in distance calculations due to noise from sensors and the environment, as fixed phase delays may not be optimized for all distances, leading to inaccuracies in distance estimation.
Innovation Solution
Implementing a ToF camera system with configurable phase delays, where multiple phase delays (e.g., between 0° and 90°) are used to determine the phase delay yielding the lowest error for each distance, creating a mapping or function to select the optimal phase delay for subsequent distance estimations, thereby reducing noise and improving accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If fixed phase delays are used in traditional ToF cameras, then device complexity is reduced and operation is simplified, but measurement precision deteriorates due to noise errors that are not optimized for all distances
Solution Approach 1:
The patent implements dynamic phase delay adjustment where the phase delay is no longer fixed but varies based on the measured distance. The system automatically selects optimal phase delays from multiple available delays (e.g., 0°, 90°, 180°, 270°) depending on the distance range, making the system adaptive rather than static. This resolves the contradiction by allowing the system to maintain low complexity for common distances while achieving high precision across all distances through automated phase delay selection.
Solution Approach 2:
The patent changes the parameter of phase delay from a fixed value to a variable that depends on distance. By implementing multiple phase delay options and selectively applying them based on measured distance ranges, the system optimizes measurement precision for different distance scenarios. This parameter change allows the same hardware to achieve high precision across varying distances without requiring complex additional components.
2Measurement precision
If multiple phase delays are implemented to reduce noise errors, then measurement precision improves, but device complexity increases due to additional sensors and synchronization requirements
Solution Approach 1:
The patent employs periodic action by using multiple phase delays corresponding to different time windows within a periodic modulation cycle. Instead of requiring multiple simultaneous sensors, the system uses a single sensor that is periodically switched between different phase delay configurations. This allows the system to capture reflected light at different phase intervals (e.g., 0°, 90°, 180°, 270°) sequentially, achieving noise reduction through temporal multiplexing rather than spatial redundancy.
Solution Approach 2:
The system dynamically switches between different phase delay configurations based on the measured distance. Rather than maintaining multiple sensors active simultaneously, the system activates only the necessary phase delay configuration for the current distance range, reducing overall system complexity while maintaining measurement precision. This dynamic switching is controlled by the clock synchronization mechanism that coordinates sensor activation with the light modulation phase.
3Reliability
If fixed phase delays are used, then ease of operation is maintained, but reliability deteriorates due to suboptimal performance at certain distances
Solution Approach 1:
The patent implements self-service by enabling the ToF camera system to automatically select and adjust the optimal phase delay based on the measured distance without requiring manual intervention. The system monitors the distance measurement and autonomously switches between different phase delay configurations to maintain optimal performance. This self-adjusting capability ensures reliable measurements across all distance ranges while keeping the operation simple for the user, as the system handles the complexity internally.
Solution Approach 2:
The system uses feedback from the distance measurement process to determine which phase delay configuration is optimal for the current range. By analyzing the measured distance and selecting the appropriate phase delay from available options, the system creates a closed-loop control mechanism that maintains measurement reliability. This feedback-driven approach allows the system to adapt to varying distances automatically, ensuring consistent performance without requiring user expertise in phase delay optimization.
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 reduces noise in distance calculations by selecting the optimal phase delay for each distance, achieving noise reductions of no more than 10% above the best case, compared to 40% noise in worst-case phasing scenarios, enhancing the accuracy of distance measurements.
Implementation Method 1
A time-of-flight (ToF) sensor can measure a distance to an object by emitting light and measuring a ToF of light that is reflected off of the object and back to the sensor
Implementation Method 2
measuring a ToF of light that is reflected off of the object and back to the sensor
Data Source
AI summary
Techniques to determine a distance associated with a surface using time-of-flight (ToF) of pulses of light occurring at a predetermined frequency. A ToF camera may include a light emitter that emits light according to one or more phase delays relative to the configured of a first storage device of multiple storage devices of the ToF camera to receive light, convert to current, and store a charge corresponding to current. For instance, a light emitter may emit pulses at a 0° phase delay (i.e., simultaneously with the opening of the first storage device), a 90° phase delay, a 180° phase delay, and a 270° phase delay. Light captured and stored as energy in the storage devices may be then be analyzed to estimate a distance to a surface of an object in an environment. After estimating a distance between the ToF camera and a surface, the ToF camera may optimize its phase delay to reduce the error associated with a subsequent distance measurement.