Dynamic Seat Back Assembly for Stable Pelvis Support
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Solution Overview
Problem
Conventional seat back arrangements for disabled users are often uncomfortable due to their inflexibility and lack of adequate support, leading to asymmetric posture and discomfort, especially for those with muscular control issues like cerebral palsy, as they fail to effectively absorb and distribute user loads.
Innovation Solution
A seat back assembly with two independently movable portions, a lower seat back portion for supporting the pelvis and an upper seat back portion for the shoulder region, featuring adjustable height, angle, and dynamic reclining movement with a shock absorber to maintain a stable pelvis angle and absorb upper body movements, providing improved support and comfort.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If a rigid seat back is used to provide strong support, then the seat can withstand user forces and provide robust support, but the seat becomes uncomfortable due to inflexibility and lacks adequate support for different body regions
Solution Approach 1:
The seat back is divided into multiple independent segments including a lumbar support portion and an upper back support portion, each capable of independent movement. This segmentation allows each region to provide appropriate support while accommodating individual movement needs, resolving the contradiction between rigid support strength and comfort by making the support structure both strong and flexible.
Solution Approach 2:
The seat back incorporates dynamic elements including a movable lumbar support portion that can move independently relative to the upper back support portion. This dynamic capability allows the seat back to adapt to user movements and loading patterns, maintaining comfort while preserving structural strength through controlled movement rather than rigid fixation.
2Device complexity
If a single rigid seat back structure is used, then the seat structure can be simplified, but the seat cannot effectively absorb and distribute user loads leading to asymmetric posture
Solution Approach 1:
The seat back is segmented into functionally distinct portions (lumbar support portion and upper back support portion) that can move independently. This segmentation enables each region to respond to specific loading patterns, effectively distributing user loads across different body regions and preventing asymmetric posture, while the overall structure remains relatively simple in concept.
Solution Approach 2:
Different portions of the seat back are designed with different movement characteristics and support properties tailored to specific anatomical regions. The lumbar support portion has independent movement capability suited for lower back support, while the upper back support portion provides different characteristics appropriate for upper back support, optimizing postural reliability through localized functional differentiation.
3Device complexity
If the entire seat back moves as a single unit, then the seat back structure is simpler, but the pelvis position is altered when the seat back moves causing the seat back to force the user forward
Solution Approach 1:
The seat back is divided into a movable lumbar support portion and a relatively stable upper back support portion. This segmentation allows the lumbar region to move independently to absorb user loading without necessarily moving the entire seat back structure, thereby maintaining pelvis position stability while still providing dynamic response to user needs.
Solution Approach 2:
The independent movement capability is extracted and applied specifically to the lumbar support portion rather than the entire seat back. This localized movement extraction allows the seat back to absorb user loading and provide comfort while the upper back and pelvis regions maintain more stable positioning, preventing the unwanted forward forcing effect.
4Ease of operation
If conventional spring mechanisms are used for dynamic seat back movement, then the seat back can flex to absorb loading, but disabled users may respond by continually moving and bouncing against the seat back requiring reinforcement
Solution Approach 1:
The seat back incorporates controlled dynamic movement through independently movable portions with dampers that provide smooth, regulated motion. This dynamic design allows the seat back to flex and absorb user loading comfortably while the damper mechanism controls the movement to prevent excessive bouncing or oscillation, maintaining both flexibility and structural robustness without requiring excessive reinforcement.
Solution Approach 2:
The damper mechanisms in the movable portions provide passive feedback control by resisting movement based on the applied load. This feedback mechanism naturally dampens oscillations and prevents the kind of continual bouncing motion that occurs with simple spring mechanisms, allowing the seat to remain flexible and comfortable while maintaining robustness against repeated impact loading.
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 seat back assembly maintains a stable pelvis angle, absorbs forces associated with extensor patterns, and ensures better postural support by allowing independent movement of the upper and lower back portions, reducing discomfort and improving user positioning.
Implementation Method 1
featuring adjustable height, angle, and dynamic reclining movement with a shock absorber to maintain a stable pelvis angle and absorb upper body movements
Data Source
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Figure 5A~5C
AI summary
A seat back assembly (16) for a seat (10), comprising an upper seat back portion (24) for supporting an upper portion of a user's back and a lower seat back portion (22) for supporting a user's pelvis and pelvic region. The lower seat back portion (22) and the upper seat back portion (24) are independently adjustable. The upper seat back portion (24) can be reclined to one of a number of fixed angular positions and it is arranged and configured for dynamic angular movement under a load over a range of positions. The dynamic movement of the upper seat back portion (24) is controlled by a shock absorber (44) having adjustable damping means for providing a required level of tension and rebound in relation to the dynamic back action of the upper seat back portion (24).