Nested Joint Encoder Structure for Compact Robot Rotation
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Solution Overview
Problem
Existing rotational structures for robots, particularly care robots and exoskeletons, face issues with encoder malfunction due to external forces, require a compact and lightweight design, and struggle with easy separation and coupling with other members while maintaining positioning accuracy.
Innovation Solution
A rotational structure with an encoder integrated inside, using a hollow portion around the shaft member, where the detection target member and detector rotate together, eliminating the need for external casing and reducing components, and employing an optical encoder with reflective or transmission scales for accurate angle measurement without transmission elements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of repair
If the encoder is provided outside the movable part of the joint structure, then the encoder can be easily accessed and maintained, but the encoder is highly susceptible to malfunction from external forces such as shocks
Solution Approach 1:
The encoder is nested inside the movable part of the joint structure, specifically within the rotational member or base member. The detection target member and detector are positioned within the hollow portion formed by the rotational member, protecting the encoder from external forces while maintaining functional integrity.
2Device complexity
If the encoder is provided outside the movable part, then the encoder structure is simple, but the joint structure size increases in the axial direction
Solution Approach 1:
The encoder components are nested within the hollow portion of the rotational member, utilizing the existing structural space. This eliminates the need for additional axial space that would be required if the encoder were mounted externally, thereby maintaining a compact joint structure.
3Reliability
If a separate bearing component is provided for the encoder, then the encoder is protected from stress, but the number of components and assembly steps increases
Solution Approach 1:
The bearing function for the encoder is merged with the existing bearing of the joint structure. The detector is positioned within the hollow portion formed by the rotational member, and the existing bearing structure serves dual purposes: supporting the rotational member and supporting the encoder components, thereby eliminating the need for separate bearing components.
4Ease of manufacture
If the encoder is provided outside the movable part, then the encoder can be easily installed, but the joint structure weight increases
Solution Approach 1:
The encoder components are integrated into the existing structural components of the joint. The detection target member is formed as part of the rotational member or base member, and the detector is positioned within the hollow portion, eliminating the need for additional supporting structures and reducing overall weight.
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
This design significantly reduces the likelihood of encoder malfunction from external forces, achieves a compact and lightweight structure, and enables secure, accurate coupling with other members, while allowing operation in harsh environments like MRI scanners or high humidity.
Implementation Method 1
a circuit board having a main surface provided with an optical sensor which transmits and receives light to detect a rotational state of the disc part to and from the disc part
Data Source
AI summary
A rotational structure is configured such that a hollow portion, in which a base member is opposed to a rotational member, is formed around a shaft member. An encoder provided in the hollow portion includes a detection target member rotated together with one of the rotational member and the base member and having a physical quantity changing in a circumferential direction, and a detector capable of detecting the physical quantity of the detection target element and rotated together with the other of the rotational member and the base member.