Multi-Robot Pose Estimation with Particle Exchange at Rendezvous

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Solution Overview

Problem

Current multi-robot positioning methods face challenges in accurately estimating robot poses due to odometry errors, high communication bandwidth requirements, and computational complexity, especially when fusing sensor measurements and relative pose information between robots.

Innovation Solution

A probabilistic multi-robot positioning system using a particle filter that allows robots to exchange particles upon rendezvous, reducing the need for raw sensor measurements storage and communication bandwidth, and employs random pairing of particles to reduce computational complexity while ensuring performance guarantees through Bayesian inference principles.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If robots exchange all measurements (odometry and laser scans) between rendezvous, then positioning accuracy is improved, but communication bandwidth requirement increases excessively

Engineering Contradiction:
Improvepositioning accuracyVSAvoidcommunication bandwidth
Core Design Contradiction:
Measurement precisionVSQuantity of substance

Solution Approach 1:

The patent extracts only the essential pose information (particles representing robot pose and covariance matrices) from the complete sensor measurements, and exchanges only this extracted information between robots during rendezvous. This eliminates the need to transmit large volumes of raw odometry and laser scan data while preserving the critical positioning information needed for accurate multi-robot localization.

Inventive Principle:
Principle #2Taking out (Extraction)

Solution Approach 2:

The patent performs preliminary processing of sensor measurements by each robot to compute pose particles and covariance matrices before the rendezvous occurs. This advance preparation transforms raw measurements into compact, exchangeable pose information, reducing the communication burden during actual rendezvous while maintaining positioning accuracy.

Inventive Principle:
Principle #10Preliminary action

2Measurement precision

If robots exchange all measurements between rendezvous, then positioning accuracy is improved, but memory storage requirement increases

Engineering Contradiction:
Improvepositioning accuracyVSAvoidmemory storage
Core Design Contradiction:
Measurement precisionVSQuantity of substance

Solution Approach 1:

The patent extracts only the essential pose information (particles representing robot pose and covariance matrices) from the complete sensor measurements, and exchanges only this extracted information between robots during rendezvous. This eliminates the need to transmit large volumes of raw odometry and laser scan data while preserving the critical positioning information needed for accurate multi-robot localization.

Inventive Principle:
Principle #2Taking out (Extraction)

Solution Approach 2:

The patent performs preliminary processing of sensor measurements by each robot to compute pose particles and covariance matrices before the rendezvous occurs. This advance preparation transforms raw measurements into compact, exchangeable pose information, reducing the communication burden during actual rendezvous while maintaining positioning accuracy.

Inventive Principle:
Principle #10Preliminary action

3Measurement precision

If density trees are used to estimate robot pose from particles, then positioning accuracy is improved, but computational complexity increases

Engineering Contradiction:
Improvepose estimation accuracyVSAvoidcomputational complexity
Core Design Contradiction:
Measurement precisionVSDevice complexity

Solution Approach 1:

The patent replaces the complex, computationally intensive density tree data structure with a simpler, more efficient particle representation that uses minimal memory and computational resources. This substitution maintains pose estimation accuracy while dramatically reducing the computational burden, making the system suitable for resource-constrained mobile robots.

Inventive Principle:
Principle #27Cheap short-living objects (Disposable)

Solution Approach 2:

The patent changes the representation parameters from dense occupancy grid maps and complex density trees to a sparse set of pose particles with covariance matrices. This parameter transformation reduces computational complexity from polynomial to linear time complexity while preserving the probabilistic nature of pose estimation.

Inventive Principle:
Principle #35Parameter changes

4Measurement precision

If all pairs of particles from two robots are compared, then pose estimation accuracy is improved, but computational complexity becomes O(K^2)

Engineering Contradiction:
Improvepose estimation accuracyVSAvoidcomputational complexity
Core Design Contradiction:
Measurement precisionVSDevice complexity

Solution Approach 1:

The patent applies partial action by comparing only a subset of particle pairs rather than all possible pairs between two robots. By strategically selecting which particles to compare based on their weights and spatial distribution, the system achieves accurate pose estimation with significantly reduced computational complexity, avoiding the O(K^2) burden of exhaustive comparison.

Inventive Principle:
Principle #16Partial or excessive action

Data Source

PatentEP3678822B1System and method for estimating pose of robot, robot, and storage medium
Publication Date: 2022.05.18 MITSUBISHI ELECTRIC CORP
  • EP3678822B1 patent drawingFigure 1A
  • EP3678822B1 patent drawingFigure 1B
  • EP3678822B1 patent drawingFigure 1C

AI summary

A system for estimating a pose of a robot, the pose including at least one of a location and orientation of the robot, includes a particle filter to track the pose of the robot using particles that defining a probability of a pose of the robot and a particle tuner to update the particles of the robot based on particles of neighboring robot. Upon receiving data indicative of a relative pose between a pose of the robot and a pose of a neighboring robot, and particles of the neighboring robot, the particle tuner pairs an arbitrarily sampled particle of the robot with an arbitrarily sampled particle of the neighboring robot, determines a weight of the paired particles in reverse proportion to an error between a relative pose defined by the paired particles and the relative pose between the robot and the neighboring robot, and updates the particles of the robot in accordance to the weights of corresponding paired particles.