Rehabilitation Device with Constant Load Mechanism
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Solution Overview
Problem
Existing motor rehabilitation devices struggle to effectively reduce articulation stresses from limb weight while maintaining a natural workspace range, leading to cumbersome designs with high inertia and limited movement variability.
Innovation Solution
A sensorized device with a mechanism providing three translational and three rotational degrees of freedom, featuring a constant vertical load application point that adjusts to accommodate varying limb positions, using a combination of kinematic pairs and a pantograph to minimize link lengths and inertia, allowing for extensive movement without the need for user-specific setup.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Force
If passive balancing techniques are used to reduce limb weight, then articulation stresses are reduced, but device mechanics are complicated and movement amplitude is limited
Solution Approach 1:
The patent employs passive balancing techniques using counterweights integrated into the device structure to compensate for limb weight. The counterweight system generates forces that offset gravitational effects on the user's limb, reducing articulation stresses without requiring active actuators. This resolves the contradiction by achieving force compensation through passive mechanical means rather than complex active control systems.
2Length of moving object
If long links are used in the articulated parallelogram to achieve greater vertical movement, then movement amplitude increases, but mechanical stresses increase and device dimensions increase
Solution Approach 1:
The patent implements a dynamically adjustable mechanism where the effective link length in the articulated parallelogram can vary during operation. The mechanism adapts its configuration based on the required movement range, allowing shorter links to be used when possible to reduce stresses, while still achieving the necessary vertical movement through dynamic reconfiguration rather than relying on fixed long links.
3Length of moving object
If long links are used in the articulated parallelogram to achieve greater vertical movement, then movement amplitude increases, but device transverse dimensions increase
Solution Approach 1:
The patent resolves the spatial contradiction by transitioning from a two-dimensional planar mechanism to a three-dimensional configuration. The articulated parallelogram is arranged in a spatial configuration that allows vertical movement to be achieved through combinations of rotational degrees of freedom in multiple directions, rather than requiring long horizontal links. This enables compact device dimensions while maintaining the required vertical workspace range.
4Adaptability or versatility
If the device is designed to cover the natural workspace of the limb, then movement variability increases, but device complexity increases
Solution Approach 1:
The patent implements a universal mechanism design where a single articulated parallelogram structure with six degrees of freedom serves multiple functions: it provides passive balancing, enables full natural workspace coverage, and accommodates various limb positions and orientations. The mechanism's geometric configuration and degree of freedom distribution allow it to handle diverse movement requirements without requiring separate specialized components for each function, thereby reducing overall device complexity.
Data Source
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AI summary
A device (1) for carrying out rehabilitation exercises, or training, of a limb, for example of the upper limb (40), of an operator (150). The device (1) comprises a fixed base (10) and a movable interaction element (60) arranged in contact and integral to a medial segment (42, 142), of the limb (40, 140), of the operator (150). In case of the upper limb (40) the medial segment, i.e. the forearm (42) of the operator (150), is set between elbow articulation (E) and the wrist articulation (W). The movable interaction element (60) and the base (10) are connected by a mechanism comprising a primary section Si equipped with, for example, of six pivot joints (21-26), connected by rigid links (12-16) and for moving the movable interaction element (60) in a workspace with respect to the fixed base (10). Furthermore, is provided a secondary section (S2), kinematically depending to the primary section (Si). The device (1) comprises, furthermore, a means for generating a vertical load (C) substantially fixed at a point (O3' ) integral to a link of the secondary section (S2). More in detail, the means (30' ) of generating the load (C) and said mechanism are adapted to apply a force vertical F proportional to the load (C), and therefore fixed, in a predetermined balance point (45).