Robot Behavior Tree Control for Reactive Task Execution

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Solution Overview

Problem

Existing robot control methods, such as finite state machines, are inadequate for robots that need to react to complex and dynamic environments, as they are not well-suited for handling versatile tasks and decision-making processes.

Innovation Solution

The use of a behavior tree architecture that comprises nodes with specific functions and data flow management, allowing for modular and flexible control of robot tasks, prioritization, and error handling, enabling robots to react to their surroundings effectively.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If finite state machines are used for robot control, then the control structure is simple, but the robot cannot handle versatile tasks and react to complex dynamic environments

Engineering Contradiction:
Improveability to handle versatile tasksVSAvoidcontrol structure complexity
Core Design Contradiction:
Adaptability or versatilityVSDevice complexity

Solution Approach 1:

The behavior tree architecture segments complex robot control into hierarchical nodes (composite nodes and execution nodes), where each node represents a specific task or behavior. This segmentation allows the robot to handle versatile tasks by composing simple behavioral units into complex sequences, resolving the contradiction between task versatility and control structure complexity.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The behavior tree implementation dynamically evaluates node execution status (running, success, failure) and adapts the control flow based on real-time conditions. The tree structure allows dynamic selection of alternative behaviors through selector nodes and conditional execution through decorator nodes, enabling the robot to react to complex dynamic environments while maintaining manageable control complexity.

Inventive Principle:
Principle #15Dynamics

2Adaptability or versatility

If behavior tree architecture is used for robot control, then the robot can react to complex environments, but the implementation complexity increases

Engineering Contradiction:
Improvereactivity to environmentVSAvoidimplementation complexity
Core Design Contradiction:
Adaptability or versatilityVSDevice complexity

Solution Approach 1:

By dividing behavior into discrete executable nodes with clear interfaces (run method returning status), the implementation complexity is managed through modular design. Each node handles specific environmental reactions independently, making the overall complex behavior systematic and maintainable.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The behavior tree architecture provides universal control mechanisms that work across different robot tasks and environments. The standardized node interface and execution model allow the same framework to handle diverse behaviors (navigation, manipulation, interaction), reducing implementation complexity compared to task-specific control systems.

Inventive Principle:
Principle #6Universality (Multi-functionality)

3Ease of manufacture

If modular sub-actions are used to describe robot behavior, then task implementation is simplified, but data management between tasks becomes challenging

Engineering Contradiction:
Improvetask implementation easeVSAvoiddata flow management complexity
Core Design Contradiction:
Ease of manufactureVSDevice complexity

Solution Approach 1:

The behavior tree introduces intermediate data structures and communication mechanisms between nodes. Data flows through the tree hierarchy via parent-child node relationships, with composite nodes mediating data exchange between multiple execution nodes. This intermediary structure simplifies modular task implementation while systematically managing data flow complexity.

Inventive Principle:
Principle #24Intermediary (Mediator)

Data Source

PatentUS11338434B2Controlling process of robots having a behavior tree architecture
Publication Date: 2022.05.24 JUNGHEINRICH AG
  • US11338434B2 patent drawing
  • US11338434B2 patent drawing
  • US11338434B2 patent drawing

AI summary

The present invention relates to a method for controlling a robot, the method including usage of a behavior tree architecture for tasks performed by the robot. The present invention also relates to a system comprising a data processing means adapted to carry out the method, wherein the system preferably comprises a robot. The present invention also relates to a use of a behavior tree architecture for programming, supervision, introspection and/or debugging.