Active sitting device with central pivot
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Solution Overview
Problem
Existing sitting devices fail to promote active sitting while maintaining a greater than 90-degree hip angle, engaging leg and core muscles, allowing wide range of motion in the pelvis, thoracic, and cervical spine, and returning to upright without mechanical resistance, while also being self-standing and comfortable for extended use.
Innovation Solution
A sitting device with a pivot joint located between the seat and base, a counterweight, and a gas lift system that allows 10-20 degrees of angular movement off the vertical axis, encouraging active engagement of legs and core muscles, and featuring a contoured seat for comfort and stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If springs or elastic elements are used to bring the central shaft back to upright, then the device can return to vertical alignment, but mechanical resistance increases reducing the need for user core engagement
Solution Approach 1:
The patent employs a counterweight mechanism where the seat and backrest assembly acts as a counterbalance to the base. When the user leans forward, the center of gravity shifts, causing the seat to pivot forward on the curved base. The counterweight effect is achieved through the distribution of mass in the seat assembly relative to the base, creating a seesaw-like motion that returns the device to vertical when the user releases the forward lean, without requiring springs or elastic elements.
Solution Approach 2:
The base of the device features a curved or convex shape rather than a flat surface. This curvature allows the device to rock forward and backward in a controlled manner. When the user leans forward, the curved base facilitates smooth angular movement of the seat assembly. The curvature geometry is designed to provide minimal resistance during the rocking motion while still guiding the device back to its stable vertical position, eliminating the need for mechanical springs.
2Stability of the object's composition
If the base is rigidly fixed at a right angle to the ground, then the device is stable, but whole-body movement range is limited
Solution Approach 1:
The base is designed with a curved or convex lower surface instead of being rigidly fixed perpendicular to the ground. This curvature allows the base to rock forward and backward along its curved surface, enabling the seat and backrest to tilt at angles greater than 90 degrees relative to the user's torso. The curved geometry provides a stable resting position when vertical while allowing extensive angular movement when the user leans forward, achieving both stability and adaptability.
Solution Approach 2:
The device transitions from a static, rigid base configuration to a dynamic system where the base can rock and the seat assembly can pivot. The curved base enables controlled rocking motion, and the connection between the seat assembly and base allows angular adjustment. This dynamic design adapts to the user's movements, providing stability when needed and movement freedom when the user leans forward, thereby increasing whole-body movement range while maintaining overall device stability.
3Device complexity
If the seat is rigidly set at ninety degrees to the central column, then the structure is simple, but pelvis and spine freedom of movement is limited
Solution Approach 1:
The connection between the seat assembly and the central column is designed to allow angular movement rather than being rigidly fixed at ninety degrees. The seat assembly can tilt forward and backward relative to the column, enabling the user's pelvis to move freely through a larger range of motion. This dynamic connection maintains structural simplicity by using straightforward pivot points or joints rather than complex mechanisms, while significantly increasing freedom of movement for the pelvis and spine.
Solution Approach 2:
The sitting device is divided into separable functional segments: the base, the central column, and the seat assembly with backrest. The seat assembly is connected to the column through a joint that allows independent angular movement. This segmentation enables each component to move relative to the others, providing freedom of movement for the user's body while keeping each individual component structurally simple and easy to manufacture.
4Adaptability or versatility
If a convex base is used to provide large range of motion, then movement freedom increases, but the device cannot stand on its own and requires user assistance to position
Solution Approach 1:
The device uses a counterbalanced design where the mass distribution between the base and the seat assembly creates a stable equilibrium in the vertical position. The center of gravity of the entire device is positioned such that when the device is upright, it naturally remains stable without requiring external support. The curved base works in conjunction with this counterbalance effect to allow forward rocking motion while ensuring the device returns to and remains stable in its vertical standing position, enabling it to stand on its own without user assistance for positioning.
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 device promotes active sitting by requiring continuous engagement of leg and core muscles for balance, enhances spinal mobility, and returns to upright with minimal resistance, standing independently and maintaining comfort over time.
Implementation Method 1
by means of gravity
Implementation Method 2
pivot joint located between the seat and base, a counterweight, and a gas lift system that allows 10-20 degrees of angular movement
Implementation Method 3
a gas lift system that allows 10-20 degrees of angular movement off the vertical axis
Data Source
AI summary
A sitting device that encourages the active engagement of the user to remain upright. A seat (14) supported by a central column (12) passes through a pivot joint (16) supported by a base (10). The pivot joint (16) is located substantially at the median of the central column (12) between the seat (14) and the bottom of the base (10). The central column (12) pivots angularly providing the user mobility in his or her hips and lumbar, thoracic, and cervical spine. The central column (12) and seat (14) are brought back to vertical when the sitting device is not in use by means of a counterweight (18) affixed to the bottom of the central column (12). The length of the central column (12) may be adjustable to allow the user to select the desired height of the seat (14). The pivot joint (16) may be a spherical plain bearing, spherical ball bearing, gimbal bearing, spherical thrust bearing, or other device that allows the central column (12) to pivot angularly. The base (10) supporting the pivot joint (16) and central column (12) may contain as few as one leg and as many legs as needed to support the user. The movement of the pivot joint (16) may be inhibited by affixing a collar lock (40). The frictional resistance of the pivot joint (16) may be adjusted with a set screw (50).