Crossed Link Robot Joint Expanding Bending Range
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Solution Overview
Problem
Conventional robot joint structures face limitations in expanding the range of motion in the bending direction without causing physical interference with links or covers, and they often suffer from reduced movable range in the extension direction due to singularity postures, which restricts the critical value of driven speed.
Innovation Solution
A robot joint structure is designed with a first and second main link connected through a first and second movable link, where the rotation axes are arranged in a quadrangle configuration with diagonally opposed axes connected by these links, allowing them to cross and be driven by an actuator, thereby increasing the joint's overall angle of rotation and expanding the range of motion in the bending direction while minimizing interference and singularity-related constraints.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If the rotation axis is offset outward to expand bending range of motion, then physical interference is avoided, but the critical value of driven speed is reduced due to singularity constraints
Solution Approach 1:
By segmenting the rotation into two separate axes, the patent eliminates the singularity constraint that limits driven speed in the single-axis offset configuration. Each rotation axis operates independently within its own optimal range, allowing higher critical speeds without encountering singularity-induced control divergence.
Solution Approach 2:
The patent changes the rotational parameters by introducing a second rotation axis with different angular and positional characteristics. This parameter change allows the system to achieve the desired bending range of motion while maintaining higher critical driven speeds through the alternative rotational path provided by the second axis.
2Device complexity
If a single axis is used to interconnect links, then the structure is simplified, but physical interference occurs between links and covers requiring axis offset
Solution Approach 1:
The patent segments the single rotation axis into two separate rotation axes positioned at different locations. This segmentation allows each axis to operate in a different spatial plane, eliminating the physical interference problem that would require offsetting a single axis while maintaining relatively simple link and cover structures.
Solution Approach 2:
By introducing a second rotation axis, the patent utilizes additional spatial dimensions to separate the motion paths of the links and covers. This dimensional separation allows both links and covers to maintain simple, compact structures without requiring outward offsets, as the two rotation axes provide independent motion pathways that avoid physical interference.
Data Source
AI summary
In a robot of an elbow joint of a humanoid robot, a first main link and a second main link are connected through a first movable link and a second movable link, and the two movable links are arranged to cross. Specifically, in a quadrangle whose apices are formed by rotation axes A, B, C and D, when assuming that rotation axes diagonally opposed to each other are A and C, and B and D, the rotation axes A and C are connected through the first movable link and the rotation axes B and D are connected through the second movable link in such a manner that the first and second movable links are disposed to cross, and that the rotation axis A is driven by the actuator to drive the first movable link, such that the first and second main links are displaced relative to each other. In addition, the first movable link is rotatably connected to a first plate and a second plate through the rotation axis A, while the second movable link is rotatably connected to the first plate through the rotation axis B. With this, it becomes possible to increase the overall driven angle of the joint relative to the input, expand the range of motion of the joint in the bending direction, and also raise the critical value of the driven speed (i.e., rotational speed).