Elbow Orthosis Stop Mechanism for Adjustable Motion Limits
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Solution Overview
Problem
Existing elbow orthoses for patients with spasticity after cardiovascular accidents are cumbersome to set up, require highly qualified operators, and have complex mechanical stop arrangements that are not intuitive.
Innovation Solution
An elbow orthosis with a simplified mechanical stop arrangement featuring aligned circular slots and a pin mechanism that allows easy adjustment to a patient's morphology and pathology, combined with a worm-and-wheel transmission and an electric gear-motor for controlled angular movement.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a complex mechanical stop arrangement with aluminum switches is used to limit angular movement, then the angular movement can be limited, but the device becomes cumbersome to set up and requires highly qualified operators
Solution Approach 1:
The mechanical stop arrangement is divided into separate modular components: a first plate with a first circular slot, a second plate with a second circular slot, and a crank with a pin. These segmented components can be independently assembled and adjusted, allowing the angular movement limitation to be configured without requiring complex pre-assembled mechanisms or highly skilled operators.
Solution Approach 2:
The mechanical stop arrangement transitions from a static pre-configured system to a dynamic adjustable system. The circular slots and pin mechanism allow the angular movement limits to be dynamically adjusted according to patient-specific requirements, enabling flexible adaptation while maintaining simplicity in the setup process.
2Reliability
If pre-configured aluminum switches are used for limiting angular movement, then the angular movement can be controlled, but the adaptation to actual use takes time and requires highly qualified operators
Solution Approach 1:
The mechanical stop arrangement is designed with pre-configured circular slots and pin mechanisms that are ready for immediate adjustment. The components are prepared in advance with appropriate tolerances and alignment features, allowing quick adaptation to different patient configurations without requiring time-consuming pre-assembly or complex calibration procedures.
Solution Approach 2:
The system enables easy parameter changes by allowing the angular movement limits to be adjusted by repositioning the crank and pin within the circular slots. This parameter adjustment can be performed quickly by less qualified operators, reducing the time required for adaptation to actual patient use while maintaining reliable angular movement control.
3Reliability
If a complex mechanical stop arrangement is used, then angular movement can be limited, but the device becomes relatively expensive
Solution Approach 1:
The complex pre-configured switch mechanism is extracted and replaced with a simpler pin-and-slot mechanism. The essential function of limiting angular movement is maintained, but the implementation uses basic mechanical elements (plates, slots, and a crank with pin) rather than complex pre-assembled components, thereby reducing device complexity and cost while preserving reliability.
Solution Approach 2:
The mechanical stop arrangement uses simple, inexpensive components that can be easily manufactured and replaced. The circular slots and pin mechanism can be implemented using basic machining operations on standard materials, eliminating the need for expensive pre-configured aluminum switches and complex assembly processes, thus reducing overall device cost while maintaining functional reliability.
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
Facilitates quick and intuitive setup for left or right arm use, ensuring safe and effective rehabilitation by allowing easy adaptation to individual patient needs.
Implementation Method 1
A worm-and-wheel transmission drives the rotation shaft, which defines the first rotation axis, from the rotational movement of the output shaft of the electric gear-motor
Implementation Method 2
A mechanical stop arrangement is configured for limiting the angular movement of the second fitting with respect to the first fitting around the first rotation axis. The mechanical stop arrangement includes a first plate, with a first circular slot, and a crank secured to the rotation shaft and equipped with a pin engaged in the first circular slot
Implementation Method 3
An angular sensor for sensing the angular position of the second fitting with respect to the first fitting around the first rotation axis
Implementation Method 4
with a torque sensor for sensing a torque exerted on the articulation mechanism by the electric gear-motor
Data Source
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AI summary
This elbow orthosis comprises a first fitting, a second fitting and a mechanical stop arrangement (40) configured for limiting the angular movement of the second fitting with respect to the first fitting around a first rotation axis (A1). The mechanical stop arrangement (40) includes first and second plates (402, 404), each provided with a circular slot (4024, 4044) and a series of through holes (4028, 4048) spread on a circle centered on a central axis (A402, A404) of the circular, and a crank (408) equipped with a pin (409) engaged in the circular slots (4024, 4044). The first and second plates (402, 404) are aligned on a common central axis and their relative orientation around this common axis is set by aligning at least one through hole (4028) of the first plate with one through hole (4048) of the second plate. Some portions of the circular slots (4024, 4044) overlap, depending on the orientation of the first and second plates around the common axis. The extremities (4024A, 4024B, 4044A, 4044B) of the overlapping portions of the circular slots define the amplitude of the maximum angular movement of the second fitting with respect to the first fitting when it is driven by a worm-and-wheel transmission (22).