Bipedal Leg Link Structure With Passive Joints for Compact High Force
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Solution Overview
Problem
Existing bipedal walking robot leg structures face challenges in achieving optimal configuration due to their serial or parallel link types, which either lack driving force or are difficult to use in narrow spaces, and require complex design parameters.
Innovation Solution
A leg structure with a five-node link mechanism and passive joints, where the first and second Jacobian matrices satisfy specific formulas to emulate the dynamics of a linear motion spring, allowing for a parallel link type with high driving force and compact design.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If a serial link type structure is used, then the structure is small and suitable for narrow spaces, but the driving force is low and it is difficult to perform bipedal walking
Solution Approach 1:
The leg structure is divided into multiple links (thigh link, shin link, foot link) connected by passive joints, creating a multi-segmented mechanism that increases driving force while maintaining compact size. The segmentation allows each link to contribute to the overall motion, enabling bipedal walking capability.
Solution Approach 2:
The patent introduces a parallel link type structure with multiple degrees of freedom, transitioning from a simple serial arrangement to a more complex spatial mechanism. This dimensional change enables the structure to generate sufficient driving force for bipedal walking while keeping the overall footprint small.
2Force
If a parallel link type structure is used, then the driving force is high and suitable for bipedal walking, but it is difficult to use in a narrow space
Solution Approach 1:
The passive joints are designed with specific local characteristics - they allow relative rotation between links while maintaining a compact form factor. Each joint is optimized to provide the necessary rotational freedom locally without increasing the overall volume of the leg structure, enabling high driving force in a compact configuration.
3Adaptability or versatility
If each structure is made up of a large number of members with predetermined length and angle parameters, then the configuration can be optimized, but it is difficult to design and obtain an optimum configuration
Solution Approach 1:
The patent transforms the design problem from optimizing multiple geometric parameters (lengths and angles of many members) to selecting spring constants for two passive joints. This parameter transformation simplifies the design process while maintaining the ability to achieve optimal configuration for bipedal walking.
Solution Approach 2:
The passive joints with springs automatically adjust the leg configuration during walking by utilizing the spring constants to control micro displacements. The system self-optimizes its configuration through the elastic properties of the springs, eliminating the need for complex real-time control of multiple geometric parameters.
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 structure efficiently realizes the dynamics of a linear motion spring, simplifying spring design and enabling miniaturization while maintaining high driving force, suitable for bipedal walking in various environments.
Implementation Method 1
constants C2 and C4 of a spring which controls the micro displacement δθ of the two passive joints
Data Source
AI summary
A structure of the present invention has a plurality of links (L) which link a lumbar side connection part (S) and a grounding part (E), and passive joints (M) which link the links (L) to each other, in which a second Jacobian matrix Jp in a coordinate system obtained by rotating a coordinate system of a first Jacobian matrix J which associates a displacement vector δp of the grounding part (E) with a micro displacement vector δθ of each of the passive joints (M) at an angle θp satisfies following Formula (1) or Formula (2) using spring constants k1 and k2 and constants C2 and C4 of a spring which controls the micro displacement δθ of two passive joints (M).[Math. 1]Jp=[Jp11±c2Jp11Jp21∓c4Jp21](1)Jp=[Jp11±c2Jp21Jp21∓c4Jp11](2)