LSTM Pose Estimation via Segmented IMU Processing
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Solution Overview
Problem
Existing pose estimation methods in VR and AR systems face delays due to complex calculations and tight coupling with multiple sensors, leading to inaccuracies and user inconvenience when the output image does not match the user's real-time pose.
Innovation Solution
A method using a loose coupling approach with an inertial measurement unit (IMU) to estimate the device's pose by generating IMU data, smoothing it, and employing a long-short-term memory (LSTM)-type recurrent neural network to predict future poses, while also determining static states and adjusting virtual objects accordingly.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a tight coupling method using many sensors is used to detect the pose of the device, then the accuracy of pose detection is improved, but the calculation complexity and processing time increase due to the amount of data and many constraints to be considered
Solution Approach 1:
The patent segments the pose estimation process into two distinct stages: a tight coupling stage using multiple sensors (IMU, magnetometer, accelerometer, gyroscope) for high-accuracy pose detection, and a loose coupling stage using only IMU data for prediction. This segmentation allows the system to apply complex calculations only when necessary (tight coupling) and use simpler methods for continuous tracking (loose coupling), thereby reducing overall calculation complexity while maintaining accuracy.
Solution Approach 2:
The system performs preliminary action by using the tight coupling method to establish an initial accurate pose estimate, then uses this as a foundation for subsequent predictions via the loose coupling method. The LSTM neural network is trained in advance on data from the tight coupling stage, enabling it to predict future poses accurately without requiring real-time processing of all sensor data, thus reducing computational burden during operation.
2Measurement precision
If a tight coupling method using many sensors is used to detect the pose of the device, then the accuracy of pose detection is improved, but the processing time increases due to calculations and computations
Solution Approach 1:
The patent divides the pose estimation workflow into an offline training phase and an online prediction phase. During offline training, the system processes extensive sensor data through tight coupling to train the LSTM neural network. During online operation, only IMU data is processed through the pre-trained LSTM model, dramatically reducing processing time while maintaining accuracy. This temporal segmentation of computation allows complex processing to occur when time is not critical.
Solution Approach 2:
The system performs preliminary computation by training the LSTM neural network in advance using data from the tight coupling method. Once trained, the model can predict poses rapidly using only IMU data, eliminating the need for real-time processing of multiple sensor streams. This preliminary action transfers the computational burden from runtime to setup time, improving real-time performance.
3Device complexity
If the output image lags behind the real-time pose, then the user experiences inconvenience due to error between pose and output image, but reducing the frame rate to decrease calculation complexity increases the lag
Solution Approach 1:
The system performs preliminary action by predicting future poses using the LSTM neural network before the actual rendering time. By estimating poses at future time points based on current and past motion states, the system prepares pose data in advance, allowing the rendering pipeline to proceed without waiting for real-time sensor processing. This eliminates lag without requiring increased frame rates or reduced calculation complexity.
Solution Approach 2:
The patent implements dynamic frame rate adjustment based on device motion characteristics. When the device is stationary or moving slowly, the system can use lower frame rates with full tight coupling processing. When motion is detected, the system dynamically switches to higher frame rates using the loose coupling LSTM prediction method. This dynamic adaptation allows the system to maintain low latency during active use while conserving computational resources during static periods.
Data Source
AI summary
A method and device that estimate a pose of a device and the device are disclosed. The method may include generating inertial measurement unit (IMU) data of the device, determining a first pose of the device a first time point based on the IMU data, generating a current predicted motion state array based on the IMU data, and estimating an M-th predicted pose of the device at an M-th time point after the first time point based on the current predicted motion state array, where M denotes a natural number greater than 1.


