Filtering Underestimated Distance Measurements from Time-of-Flight Sensors

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Solution Overview

Problem

Robots equipped with periodic pulse-modulated time of flight sensors often incorrectly localize objects beyond their maximum range, leading to inefficient operation and potential human intervention due to incorrect distance measurements.

Innovation Solution

A robotic system that filters out erroneous distance measurements by segmenting depth images based on color or distance values, applying criteria such as aspect ratio and field of view, to produce a filtered depth image used for navigation.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If periodic pulse-modulated time of flight sensors are used to measure distance, then the sensor can operate within a defined maximum range, but objects beyond this range are incorrectly localized as being within range, causing erroneous distance measurements

Engineering Contradiction:

Improvedistance measurement accuracyVSAvoidlocalization accuracy

Core Design Contradiction:

Measurement precisionVSReliability

Solution Approach 1:

The patent segments the depth image into multiple groups based on color values or distance values. Each group represents a portion of the image with similar characteristics. By processing groups separately and applying filtering criteria to each, the system can identify and remove erroneous measurements while preserving valid ones, thus resolving the contradiction between measurement precision and reliability.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The patent implements a feedback mechanism where the sensor continuously monitors distance measurements and compares them against expected patterns. When an object is detected beyond the maximum range, the system uses the periodic nature of the pulse modulation to identify the error and correct the localization, improving both measurement precision and reliability through iterative validation.

Inventive Principle:

Principle #23Feedback

2Loss of information

If the sensor measures all objects in the field of view, then complete environmental mapping is achieved, but erroneous measurements from out-of-range objects cause incorrect localization and disrupt navigation

Engineering Contradiction:

Improveenvironmental mapping completenessVSAvoidobject localization accuracy

Core Design Contradiction:

Loss of informationVSMeasurement precision

Solution Approach 1:

The patent applies preliminary filtering criteria to depth image groups before they are used for navigation decisions. By pre-identifying and removing erroneous measurements based on aspect ratio, position, and other criteria, the system ensures that only accurate localization data is used for navigation, preventing disruptions while maintaining complete environmental mapping.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The patent extracts and removes erroneous distance measurement groups from the depth image while retaining valid measurements. This extraction process separates correct localization data from incorrect data, allowing the system to maintain complete environmental mapping without the negative effects of erroneous out-of-range object localization.

Inventive Principle:

Principle #2Taking out (Extraction)

3Reliability

If the robotic system stops or interrupts operation due to incorrect distance measurements, then safety is maintained, but task performance and productivity decrease

Engineering Contradiction:

Improvenavigation safetyVSAvoidtask performance

Core Design Contradiction:

ReliabilityVSProductivity

Solution Approach 1:

The patent performs preliminary filtering and validation of distance measurements before the robotic system makes navigation decisions. By pre-removing erroneous measurements that would trigger unnecessary stops, the system maintains navigation safety through accurate data while preventing productivity losses from unwarranted interruptions.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The patent implements a feedback loop that continuously validates distance measurements against multiple criteria. This feedback mechanism distinguishes between genuine obstacles requiring safety stops and erroneous measurements, allowing the system to maintain safety only when truly necessary and preserve productivity by avoiding unnecessary interruptions.

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

Improves robotic task performance, mapping, and predictability by accurately removing incorrectly localized objects, enhancing navigation and reducing unnecessary stops or interruptions.

Implementation Method 1

periodic pulse-modulated time of flight sensors

Methodology Applied

Scientific EffectTime of flight: Time of Flight

Implementation Method 2

emitting periodic light pulses and detecting the reflected light

Methodology Applied

Scientific EffectLight reflection: Reflection

Data Source

PatentUS20220163644A1Systems and methods for filtering underestimated distance measurements from periodic pulse-modulated time-of-flight sensors

Publication Date: 2022.05.26 BRAIN CORP

AI summary

Systems and methods for filtering underestimated distance measurements from pulse-modulated time of flight sensor are disclosed herein. According to at least one non-limiting exemplary embodiment, a cluster of pixels in a depth image may be identified as having incorrect distance measurements based on a set of pre-defined criteria disclosed herein. The incorrect distance measurements may be filtered from the image such that robots using depth cameras do not perceive objects as being substantially close to the robots when no objects are present.