Recurrent Neural Network Head Pose Prediction for AR Latency

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Solution Overview

Problem

Virtual Reality (VR) and Augmented Reality (AR) systems face challenges in accurately predicting user movements due to latency issues, leading to errors in content rendering and potential simulator sickness, as the time delay between user head movement and visual data rendering can result in mismatched head poses and perceived lag.

Innovation Solution

A computer-implemented method using Recurrent Neural Networks (RNNs), specifically Long Short-Term Memory (LSTM) cells and Gated Recurrent Unit (GRU) architectures, to predict head poses by modeling historical sequence data and reducing vanishing gradients, thereby improving accuracy and reducing perceived latency in VR/AR environments.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If VR/AR content is tracked and rendered remotely on a base station, then rendering quality and system performance are improved, but latency is introduced due to round-trip time from device to rendering server and back, causing errors in predicting user movements

Engineering Contradiction:
Improverendering qualityVSAvoidlatency
Core Design Contradiction:
ReliabilityVSLoss of time

Solution Approach 1:

The system performs preliminary actions by predicting future head poses before the actual rendering occurs. The RNN model forecasts user head movements in advance, allowing the rendering system to pre-compute and buffer visual content corresponding to predicted poses. This preliminary prediction and pre-rendering approach reduces the perceptible latency by ensuring that content is ready before the user actually moves their head to that position.

Inventive Principle:
Principle #10Preliminary action

Solution Approach 2:

The system dynamically adjusts the prediction horizon and rendering timing based on detected head movement patterns. The RNN continuously updates pose predictions as new head pose data arrives, and the system adapts the pre-rendering timeline dynamically. This dynamic adjustment allows the system to optimize between rendering quality and latency by flexibly responding to actual user behavior rather than following a fixed schedule.

Inventive Principle:
Principle #15Dynamics

2Device complexity

If simple prediction methods are used to compensate for latency, then computational complexity is reduced, but accuracy of head pose prediction deteriorates, leading to errors in content rendering

Engineering Contradiction:
Improvecomputational complexityVSAvoidprediction accuracy
Core Design Contradiction:
Device complexityVSMeasurement precision

Solution Approach 1:

The system replaces simple mechanical interpolation methods (such as linear extrapolation or constant velocity models) with a neural network-based predictive system. The RNN learns complex temporal patterns in head movement data and generates accurate pose predictions without requiring explicit mathematical models of head dynamics. This substitution of mechanical prediction with learning-based prediction significantly improves accuracy while keeping the computational architecture relatively simple through efficient network design.

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The system optimizes prediction accuracy by carefully selecting and tuning key parameters of the RNN model, including the number of LSTM cells, hidden layer dimensions, and training data characteristics. By changing these parameters, the system achieves high prediction accuracy without proportionally increasing computational complexity. The parameter optimization allows the model to capture essential movement patterns with minimal computational resources.

Inventive Principle:
Principle #35Parameter changes

3Ease of operation

If head pose predictions are made for future time periods to compensate for latency, then user experience smoothness is improved, but prediction errors may accumulate, causing mismatched head poses and perceived lag

Engineering Contradiction:
Improveuser experience smoothnessVSAvoidprediction accuracy
Core Design Contradiction:
Ease of operationVSReliability

Solution Approach 1:

The system implements feedback mechanisms where actual head pose measurements are continuously compared with predicted poses, and prediction errors are used to update and refine the RNN model in real-time. This feedback loop allows the system to correct accumulating prediction errors by adapting to actual user behavior patterns. The feedback ensures that even as predictions extend into the future, the model remains calibrated to the user's actual movement characteristics, preventing drift and maintaining accuracy.

Inventive Principle:
Principle #23Feedback

Data Source

PatentUS10989916B2Pose prediction with recurrent neural networks
Publication Date: 2021.04.27 GOOGLE LLC
  • US10989916B2 patent drawing
  • US10989916B2 patent drawing
  • US10989916B2 patent drawing

AI summary

Systems, methods, and computer program products are described for receiving a request for a head pose prediction for an augmented reality experience, identifying at least one positional indicator and at least one rotational indicator associated with the augmented reality experience, and providing the at least one positional indicator and the at least one rotational indicator to a Recurrent Neural Network (RNN) comprising a plurality of cells. The RNN may include a plurality of recurrent steps that each include at least one of the plurality of cells and at least one fully connected (FC) layer. The RNN may be used to generate at least one pose prediction corresponding to head pose changes for the augmented reality experience for at least one upcoming time period, provide the at least one pose prediction and trigger display of augmented reality content based on the at least one pose prediction.