Birfield Variable-Stiffness Continuum Robot Joints with Torsional Resistance
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Solution Overview
Problem
Existing continuum robots face challenges in motion modeling complexity due to limited degrees of freedom and torsional resistance, with traditional structures being complicated and difficult to model, and lacking sufficient adaptability and stiffness for various environments.
Innovation Solution
The birfield flexible variable-stiffness continuum robot unit employs a birfield joint design with two degrees of freedom, spherical pair connections, and flexible springs to provide variable stiffness and high torsional resistance, allowing for simpler modeling and improved adaptability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If traditional double-core column structure is used, then the robot can achieve basic movement, but the motion modeling becomes complicated and torsional resistance is poor
Solution Approach 1:
The robot arm is divided into multiple modular structural units, each with standardized spherical shell structures and inner race structures. This segmentation allows for simplified modeling of each unit while maintaining overall system complexity reduction through repeatability
Solution Approach 2:
Spherical pair connections are implemented using spherical shell structures and inner race structures with spherical raceways. This spherical geometry simplifies the motion modeling mathematics compared to traditional curved spline representations while providing inherent torsional resistance through the spherical contact geometry
2Stability of the object's composition
If contact-assisted structures with cam mechanisms or gear teeth are used, then the robot structure is stabilized, but each joint has only one degree of freedom and modeling difficulty increases
Solution Approach 1:
The spherical pair connections provide inherent structural stability through their spherical geometry and raceway design, eliminating the need for additional cam mechanisms or gear teeth. The spherical contact surfaces naturally guide motion while maintaining stability, and the standardized spherical geometry simplifies modeling compared to complex contact-assisted structures
Solution Approach 2:
The spherical pair connection structure serves multiple functions simultaneously: it provides structural stability, enables two degrees of freedom motion, and offers simplified modeling through standardized spherical geometry. This multi-functionality replaces the need for separate cam mechanisms or gear teeth that would otherwise be required for stability
3Strength
If traditional stiff structures are used, then the robot has good load bearing capacity, but flexibility and adaptability are reduced
Solution Approach 1:
The robot employs variable-stiffness joints that can dynamically adjust their stiffness characteristics. The spherical pair connections with flexible elements allow the structure to be stiff when load bearing is required and flexible when adaptability is needed, enabling dynamic transition between rigid and compliant states based on operational requirements
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The birfield structure enables precise and flexible manipulation with enhanced torsional resistance, variable stiffness, and improved control precision, enabling the robot to operate effectively in diverse environments.
Implementation Method 1
connection design of flexible springs is further adopted, certain stiffness is provided for a manipulator, and thus the manipulator has a variable-stiffness characteristic
Implementation Method 2
a roll ball structure makes the manipulator have high torsional resistance, be capable of bearing a large torsional load
Data Source
AI summary
Disclosed is a birfield flexible variable-stiffness continuum robot unit and a continuum robot. In the birfield flexible variable-stiffness continuum robot unit, main structural units are interconnected to constitute a continuum manipulator; joint connecting structures connect the two adjacent main structural units; a front-end unit is arranged at a foremost end of the manipulator; and a rear-end unit is arranged at a rearmost end of the manipulator. When in use, birfield joint design is adopted, a single joint has two degrees of freedom, is more flexible and variable, and the adjacent structural units rotate around a center of a sphere, so that modeling is simpler and more convenient; connection design of flexible springs is further adopted, certain stiffness is provided for the manipulator, and thus the manipulator has a variable-stiffness characteristic; and meanwhile, a roll ball structure makes the manipulator have high torsional resistance.