Dynamic Moving Average for TOF Distance Measurement

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Solution Overview

Problem

Current distance measuring technologies using time-of-flight (TOF) methods face challenges in accurately measuring distances to objects due to noise variations caused by dynamic changes, leading to mixed signals and reduced noise reduction effectiveness, especially when objects move abruptly or have low reflectance.

Innovation Solution

A distance-measuring apparatus and method that emit pulsed light, sort electrical signals into phase signals, determine dynamic changes between frames, and perform moving average calculations on either current and past frames or solely past frames based on the presence of dynamic changes to accurately calculate distances, reducing noise and ensuring precise measurements.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If moving average calculations are performed on current and past frames to reduce noise, then measurement precision improves, but reliability deteriorates when dynamic changes are present due to mixed signals

Engineering Contradiction:

Improvedistance measurement precisionVSAvoidmeasurement reliability under dynamic conditions

Core Design Contradiction:

Measurement precisionVSReliability

Solution Approach 1:

The patent dynamically adjusts the calculation method based on whether dynamic changes are detected in the measurement target. When dynamic changes are detected, the system switches to using only past frame data for moving average calculations, excluding current frame data to avoid mixing static and dynamic signals. This dynamic adaptation resolves the contradiction by maintaining measurement precision through noise reduction while ensuring reliability under dynamic conditions.

Inventive Principle:

Principle #15Dynamics

Solution Approach 2:

The system changes the parameter of data selection for calculation based on the detection result of dynamic changes. The parameter changes from including both current and past frames (for noise reduction) to including only past frames (for dynamic condition accuracy). This parameter change allows the system to optimize between precision and reliability depending on the measurement conditions.

Inventive Principle:

Principle #35Parameter changes

2Loss of energy

If moving average calculations include current frame data, then noise reduction effectiveness improves, but measurement accuracy deteriorates when objects move abruptly

Engineering Contradiction:

Improvenoise reduction effectivenessVSAvoiddistance measurement accuracy during motion

Core Design Contradiction:

Loss of energyVSMeasurement precision

Solution Approach 1:

The patent implements dynamic selection of calculation data based on motion detection. When abrupt motion is detected, the system dynamically switches to using only past frame data for moving average calculations, excluding current frame data that contains mixed signals from moving objects. This resolves the contradiction by maintaining noise reduction effectiveness for static objects while ensuring measurement accuracy during motion through conditional data selection.

Inventive Principle:

Principle #15Dynamics

Solution Approach 2:

The system uses feedback from the dynamic change detection unit to control the calculation unit's data selection. The detection result of whether dynamic changes are present feeds back into the calculation process, determining whether to include current frame data or use only past frame data. This feedback mechanism resolves the contradiction by adaptively adjusting the calculation approach based on real-time measurement conditions.

Inventive Principle:

Principle #23Feedback

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 enables accurate distance measurement regardless of dynamic changes, reducing noise and ensuring high precision by adapting moving average calculations to the presence of dynamic objects, thus stabilizing distance measurements.

Implementation Method 1

a photoreceptor system that receives and photoelectrically converts the pulsed light that is emitted from the phototransmitter system and then reflected by an object into a plurality of electrical signals

Methodology Applied

Scientific EffectPhotoelectric conversion: Photoelectric Effect

Implementation Method 2

distance measuring technologies using so-called time-of-flight (TOF) computation are known in the art in which the distance to an object is calculated based on the time it takes for the light to be emitted, reflected by the object, and return

Methodology Applied

Scientific EffectTime of flight: Time of Flight

Data Source

PatentUS10684121B2Distance-measuring apparatus which uses different calculations depending on whether the object is dynamically changing

Publication Date: 2020.06.16 RICOH CO LTD

AI summary

A distance-measuring apparatus and a distance-measuring method. The distance-measuring apparatus and the distance-measuring method include emitting pulsed light, receiving and photoelectrically converting the pulsed light emitted and reflected by an object into a plurality of electrical signals, sorting the electrical signals into a plurality of phase signals, storing data including the phase signals or a value that is based on the phase signals, determining whether or not a dynamic change is present in the object, based on the data of a current frame and at least one past frame, and calculating distance to the object using the data, according to a result of determination made by the determining. When determined that the dynamic change is not present, moving average calculations are performed on the data of at least two of the current frame and a plurality of frames including the at least one past frame.