Pixel-Based Robot MPC Using Latent Dynamics for Stable Trajectory Prediction

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Solution Overview

Problem

Existing machine learning-based approaches for robots to perform tasks are limited by model accuracy and robustness, especially in dynamic environments, leading to divergent predictions for future states and trajectories.

Innovation Solution

Training a latent robot dynamics model using unsupervised trajectories with a deep neural network architecture, combining an encoder, transition function, and decoder, and a reward function to predict future actions and trajectories from pixel-based observations, enabling few-shot learning and efficient action sequence evaluation in latent space.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Device complexity

If a simple state-space model is used to predict future states and trajectories, then the computational complexity is low, but the prediction accuracy diverges quickly from actual states

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

Solution Approach 1:

The patent transforms the prediction approach by changing the parameter representation from direct pixel-space predictions to latent-space predictions. The model compresses pixel observations into latent states through an encoder, performs transitions in this compressed space, and reconstructs future states. This parameter transformation maintains computational efficiency while significantly improving prediction accuracy by capturing essential dynamics in a lower-dimensional manifold.

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

The patent introduces a latent space dimension that bridges pixel observations and predicted states. Instead of operating directly in high-dimensional pixel space or simple state space, the model creates an intermediate latent representation layer. This dimensional transformation allows the system to capture complex dynamics without the computational burden of full pixel-space modeling, resolving the accuracy-complexity tradeoff.

Inventive Principle:
Principle #17Another dimension (Dimensionality change)

2Duration of action of moving object

If predictions are made for multiple future time instances, then the planning horizon is extended, but the predicted state and trajectory diverge quickly from actual state

Engineering Contradiction:
Improveprediction horizonVSAvoidprediction reliability
Core Design Contradiction:
Duration of action of moving objectVSReliability

Solution Approach 1:

The patent applies preliminary compression of pixel observations into latent states before performing multi-step predictions. By encoding current and past pixel observations into compact latent representations that capture essential dynamics, the model establishes accurate initial conditions for future predictions. This preliminary action in latent space prevents divergence even over extended prediction horizons, as the compressed representations are more robust to prediction errors.

Inventive Principle:
Principle #10Preliminary action

3Measurement precision

If full image generation is performed for action sequence evaluation, then the visual accuracy is high, but the computational time increases

Engineering Contradiction:
Improvevisual accuracyVSAvoidevaluation speed
Core Design Contradiction:
Measurement precisionVSProductivity

Solution Approach 1:

The patent extracts only the essential latent state representations needed for action sequence evaluation, rather than generating full images. By performing evaluation in the compressed latent space and only generating images when necessary for final visualization or detailed analysis, the system achieves rapid action sequence comparison and selection. This extraction approach maintains visual accuracy for critical assessments while dramatically improving evaluation throughput.

Inventive Principle:
Principle #2Taking out (Extraction)

Data Source

PatentUS11904467B2System and methods for pixel based model predictive control
Publication Date: 2024.02.20 GOOGLE LLC
  • US11904467B2 patent drawing
  • US11904467B2 patent drawing
  • US11904467B2 patent drawing

AI summary

Techniques are disclosed that enable model predictive control of a robot based on a latent dynamics model and a reward function. In many implementations, the latent space can be divided into a deterministic portion and stochastic portion, allowing the model to be utilized in generating more likely robot trajectories. Additional or alternative implementations include many reward functions, where each reward function corresponds to a different robot task.