Event-Based Motion Capture Using Asynchronous Light Sensors

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Solution Overview

Problem

Existing motion capture systems face limitations in capturing fast movements with high fidelity due to high computational power usage and fixed framerate, leading to low temporal resolution and high latency.

Innovation Solution

The use of event-based light sensors with asynchronous data processing to detect and track markers, allowing for high temporal resolution and reduced computational power by generating events based on light variations from markers, enabling precise motion capture with microsecond accuracy.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If frame-based cameras with fixed framerate are used to detect markers, then the system can capture motion at regular intervals, but the computational power usage increases and temporal resolution is limited

Engineering Contradiction:

Improvetemporal resolutionVSAvoidcomputational power usage

Core Design Contradiction:

Measurement precisionVSUse of energy by moving object

Solution Approach 1:

The patent transitions from static frame-based capture to dynamic event-based capture, where the sampling rate adapts to motion intensity. Events are generated asynchronously based on light intensity changes, allowing the system to capture fast movements with high temporal resolution while reducing computational load during static periods.

Inventive Principle:

Principle #15Dynamics

Solution Approach 2:

The system changes the fundamental parameter of time sampling from fixed intervals to event-driven timing. By using timestamps with microsecond precision for each event rather than processing entire frames at fixed framerates, the system achieves superior temporal resolution with reduced computational requirements.

Inventive Principle:

Principle #35Parameter changes

2Speed

If frame-based cameras with fixed framerate are used, then the system structure is simple, but the latency increases and fast movements cannot be captured with high fidelity

Engineering Contradiction:

Improvecapture speed for fast movementsVSAvoidlatency

Core Design Contradiction:

SpeedVSLoss of time

Solution Approach 1:

The event-based sensors continuously monitor light intensity and are ready to generate events immediately when changes occur, eliminating the waiting time inherent in frame-based systems. This preliminary readiness state allows the system to capture fast movements without latency delays.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

Instead of periodic sampling, the system maintains continuous monitoring capability through event-based sensors that generate events asynchronously whenever light changes occur. This continuous action ensures no motion details are lost between frames, capturing fast movements with high fidelity.

Inventive Principle:

Principle #20Continuity of useful action

3Adaptability or versatility

If conventional imaging sensors are used for localization, then the system can process images, but the fixed framerate limits the dynamics capture capability

Engineering Contradiction:

Improvedynamics capture capabilityVSAvoidsystem complexity

Core Design Contradiction:

Adaptability or versatilityVSDevice complexity

Solution Approach 1:

The patent replaces the mechanical frame-based scanning approach with an event-driven optical detection system. Event-based sensors directly convert light intensity changes into electrical signals with timestamps, eliminating the mechanical constraints of fixed framerates and enabling superior dynamics capture.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

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 significantly improves latency and temporal resolution, enabling high-fidelity movement capture with precision in microseconds and millimeters, making the system more flexible and suitable for applications like augmented and virtual reality, sports analysis, and cinema.

Implementation Method 1

receiving events asynchronously from the pixels of the at least two event-based light sensors depending on variations of incident light from the at least one marker sensed by the pixels

Methodology Applied

Scientific EffectPhotoelectric Effect: Photoelectric Effect

Data Source

PatentUS12131544B2Method for capturing motion of an object and a motion capture system

Publication Date: 2024.10.29 PROPHESEE SOLUTIONS PVT LTD

AI summary

A method for capturing motion of an object, the method comprising: installing at least one marker on the object; bringing the object having the at least one marker installed thereon in an acquisition volume; arranging at least two event-based light sensors such that respective fields of view of the at least two event-based light sensors cover the acquisition volume, wherein each event-based light sensor has an array of pixels; receiving events asynchronously from the pixels of the at least two event-based light sensors depending on variations of incident light from the at least one marker sensed by the pixels; and processing the events to position the at least one marker within the acquisition volume and capture motion of the object.