Continuum Arm Robot Coordination for Stiffness and Payload Control

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Solution Overview

Problem

Current continuum arm robots suffer from low stiffness due to the number of joints, limiting their load-carrying capacity and interaction with the environment, especially in longer lengths where deflection causes position and navigation issues, restricting their use to lightweight tasks to avoid damage.

Innovation Solution

A control system for multiple compliant robots with individual and overall control systems, synchronized clocks, and a redundancy control system to manage motion and stiffness, allowing linked movement and clamping of robots to enhance stiffness and payload capacity, while maintaining operational flexibility.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If the number of joints is increased to achieve greater dexterity and access to confined spaces, then the robot can operate in more complex areas, but the stiffness of the robot arm decreases

Engineering Contradiction:
ImprovedexterityVSAvoidstiffness
Core Design Contradiction:
Adaptability or versatilityVSStrength

Solution Approach 1:

The robot system is divided into multiple independent compliant robot segments, each with its own actuator pack and control system. These segments can be individually controlled and connected through clamping systems, allowing the robot to achieve complex configurations while maintaining stiffness through selective segment connection.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The system dynamically adjusts the number of active segments and their connection states based on task requirements. The clamping system allows segments to be connected or disconnected dynamically, enabling the robot to transition between flexible configurations for navigation and stiff configurations for load-bearing tasks.

Inventive Principle:
Principle #15Dynamics

2Length of moving object

If the length of the robot arm is increased to reach further areas, then the access capability is improved, but the deflection increases causing position and navigation issues

Engineering Contradiction:
Improvearm lengthVSAvoidposition accuracy
Core Design Contradiction:
Length of moving objectVSManufacturing precision

Solution Approach 1:

The long robot arm is segmented into multiple shorter compliant robot sections that can be connected in series. Each section maintains better positional accuracy independently, and the cumulative length achieves the required reach without the deflection problems of a single long cantilever beam.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The system uses multiple degrees of freedom and spatial arrangement of segmented sections to achieve extended reach. By configuring segments in three-dimensional space with independent actuation, the system achieves long effective length while maintaining control accuracy through redundant actuation paths.

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

3Strength

If multiple compliant robots are linked together to increase stiffness and payload capacity, then the load-carrying capacity is improved, but the control complexity increases

Engineering Contradiction:
Improvepayload capacityVSAvoidcontrol system complexity
Core Design Contradiction:
StrengthVSDevice complexity

Solution Approach 1:

Multiple compliant robots are physically connected through clamping systems to form a unified multi-segment structure. The control systems of individual robots are synchronized and coordinated through a master controller, allowing the linked system to function as a single stiff structure with enhanced payload capacity while managing control complexity through integrated control architecture.

Inventive Principle:
Principle #5Merging (Combining)

Solution Approach 2:

The control system incorporates feedback from sensors on each compliant robot segment to monitor position, orientation, and connection status. This feedback enables the master controller to coordinate the motion of linked segments, maintain synchronization, and adjust control commands in real-time to manage the complexity of controlling multiple connected robots as a unified system.

Inventive Principle:
Principle #23Feedback

Data Source

PatentEP4201601A1Continuum arm robot system
Publication Date: 2023.06.28 ROLLS ROYCE PLC
  • EP4201601A1 patent drawingFigure 1A~1B
  • EP4201601A1 patent drawingFigure 2
  • EP4201601A1 patent drawingFigure 3

AI summary

A control system for a complaint robotic system comprising at least two compliant robots each compliant robot having their own actuator pack, the control system comprising: an individual local control system associated with each of the actuator pack, the local control system providing control signals to the actuator to cause movement within the associated compliant robots, an overall control system which controls the overall motion of robots when they are proximate within a workspace, the overall control signal providing signals to the actuators associated with the at least two compliant robots, so as to cause linked movement of the continuum arm robots, and wherein each individual control system is provided with a clock, and the clocks of each individual control system is synchronized with the other, and wherein the overall control system is provided with a redundancy control system that limits the motion of the compliant robots within certain degrees of freedom, so that the motion of the at least two complaint robots does not conflict when operating under the overall control system.