Remote Center Shoulder Joint for Exoskeletons
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing mechanisms for exoskeletons and robotics require rotational freedom with a remote center of motion, often relying on complex spherical mechanisms or actuated means to support loads, which add unnecessary complexity.
Innovation Solution
A remote center mechanism using six segments in a hexagonal shape with parallel rotational axes, allowing for passive rotational motion without intersecting segments, transferring loads through intermeshing gears between a base and terminal segment.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If spherical mechanisms are used to provide rotational freedom with a remote center of motion, then rotational freedom is achieved, but device complexity increases
Solution Approach 1:
The mechanism is divided into six segments (first through sixth segments) arranged in a hexagonal configuration, where each segment performs a specific function. The segments are coupled through revolute joints at remote centers of motion, allowing the system to achieve rotational freedom while maintaining structural simplicity through functional decomposition.
Solution Approach 2:
The fourth segment acts as an intermediary between the third segment (coupled to base) and the fifth segment (coupled to terminal). This intermediate segment, along with the gear mechanism between segments three and four, mediates the motion transmission while maintaining the remote center of motion constraint, thereby simplifying the overall mechanism architecture.
2Volume of moving object
If six segments are used in a hexagonal shape with parallel rotational axes, then device profile is minimized, but manufacturing complexity increases
Solution Approach 1:
Multiple segments (first, third, fifth segments) are configured with parallel rotational axes and similar structural characteristics. The gear mechanisms between segments follow a consistent pattern (e.g., gear coupling between segments one-two, three-four, and five-six). This universality allows for standardized manufacturing processes and reduces production complexity despite the six-segment hexagonal configuration.
Solution Approach 2:
The mechanism uses parallel rotational axes (all axes are parallel to each other) rather than intersecting axes, which allows the segments to be arranged in a planar hexagonal configuration. This dimensional arrangement minimizes the volume occupied by the mechanism while maintaining the required motion capabilities, and simplifies manufacturing compared to three-dimensional intersecting axis configurations.
3Ease of operation
If intermeshing gears are used to constrain motion to one degree of freedom, then motion control is improved, but device complexity increases
Solution Approach 1:
The gear mechanisms between segments automatically constrain the motion to one degree of freedom through their inherent mechanical geometry. The intermeshing gears self-regulate the motion transmission, ensuring that only rotation about the remote center axis is permitted without requiring additional control systems or complex actuation mechanisms. The passive gear coupling provides inherent motion control.
4Device complexity
If parallel rotational axes that do not intersect are used, then mechanism simplicity is improved, but load transfer capability is reduced
Solution Approach 1:
The mechanism uses revolute joints with curved joint surfaces that accommodate rotation about parallel axes. The curved segments and joint geometries are designed to distribute loads effectively across the parallel axis configuration, compensating for the non-intersecting nature of the axes. This allows simple parallel axis geometry to maintain adequate load transfer capability through optimized contact surfaces.
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 mechanism provides one degree of freedom while minimizing device profile and transferring loads efficiently, maintaining stability and simplicity by avoiding direct coupling between segments.
Implementation Method 1
each set of segments are geared together in order to constrain the mechanism to one degree of freedom and resist applied loads
Data Source
Figure 1A
Figure 1B
Figure 2
AI summary
A remote center joint 1 is configured to rotate segment 7 relative to segment 2 along axis 15. Remote center joint 1 comprises a segment 3 coupled to base segment 2 along axis 16. Segment 4 is coupled to segment 3 about axis 17 intersecting axis 16 at first point 22. Segment 4 is coupled to segment 7 about axis 18 intersecting first point 22. Segment 5 is coupled to segment 2 about axis 19 parallel to axis 16. Segment 5 is geared to segment 3. Segment 6 is coupled to segment 5 about axis 20 intersecting axis 19 at second point 23. Segment 6 is coupled to segment 7 along axis 21 intersecting second point 23. Segment 6 is geared to segment 4. Axis 15 of rotation of terminal segment 7 relative to segment 2 connects first point 22 and second point 23.