Weight Sensor Segmentation for Multi-Occupant Monitoring

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Solution Overview

Problem

Existing weight sensing systems for beds are unable to independently monitor the weight and weight shifting of multiple individuals sharing the same bed, as they provide only a single weight reading for the entire bed, making it impossible to distinguish changes in weight between users.

Innovation Solution

A weight sensing system that uses differential weight measurements between sensors on either side of the bed, combined with a data hub for continuous data collection and processing, allows for the tracking of fluctuations in weight and differentiation of individual weights by recording absolute weight changes, enabling the monitoring of multiple occupants.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If a single weight sensing unit is placed under each leg of a bed, then the total weight of the bed and user can be measured, but it is impossible to distinguish weight changes between multiple users sharing the same bed

Engineering Contradiction:
Improveweight measurement capabilityVSAvoidindividual user weight data
Core Design Contradiction:
Measurement precisionVSLoss of information

Solution Approach 1:

The patent divides the bed into multiple zones by placing weight sensing units under different legs (head left, head right, foot left, foot right). Each sensor independently measures weight at its specific location, creating segmented weight data that can be analyzed to distinguish between multiple users based on their positional weight distributions and movements.

Inventive Principle:
Principle #1Segmentation

2Strength

If a load cell with thick base and central contact knob is used to accommodate high loads of 150 kg or more, then the load cell can handle the weight, but the load cell becomes excessively thick

Engineering Contradiction:
Improveload bearing capacityVSAvoidload cell thickness
Core Design Contradiction:
StrengthVSLength of stationary object

Solution Approach 1:

Instead of using a single thick load cell, the patent distributes the load-bearing function across multiple thinner load cells positioned at different bed legs. Each load cell handles a portion of the total weight, allowing the use of thinner, more compact sensors while collectively supporting the full bed and user weight.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The patent combines multiple load cells to achieve the required total load-bearing capacity. By merging the measurements from four separate load cells (under each bed leg), the system achieves both the necessary strength to handle 150 kg or more and the benefit of using thinner, less intrusive sensors.

Inventive Principle:
Principle #5Merging (Combining)

3Reliability

If a load cell requires fixing to a platform plate with a central foot, then the load cell can be securely mounted, but the installation becomes more complex and requires additional fasteners

Engineering Contradiction:
Improvemounting stabilityVSAvoidinstallation complexity
Core Design Contradiction:
ReliabilityVSEase of manufacture

Solution Approach 1:

Instead of requiring the load cell to be fixed to a platform plate, the patent inverts the mounting approach by placing the load cell directly on the ground floor underneath the bed. The load cell's base serves as the mounting surface, eliminating the need for platform plates, central feet, and additional fasteners, thereby simplifying installation while maintaining reliable weight measurement.

Inventive Principle:
Principle #13The other way round (Inversion)

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

Enables the independent tracking of weight and weight shifting of multiple individuals, providing insights into sleep quality, breathing, heart rate, and other activities, while minimizing data storage requirements and accommodating various bed leg configurations.

Implementation Method 1

a load cell element upon which are mounted one or more strain gauges, a base and a platform, as well as any necessary wires and cables for the strain gauge(s) to be wired e.g. in conventional Wheatstone bridge arrangements

Methodology Applied
Scientific EffectStrain gauge: Piezoresistive Effect

Data Source

PatentEP2863188B1Weight sensing
Publication Date: 2022.11.30 CARDE CHRIS
  • EP2863188B1 patent drawingFigure 1
  • EP2863188B1 patent drawingFigure 2
  • EP2863188B1 patent drawingFigure 3

AI summary

A weight sensor comprising a weighing platform and a load cell coupled to the platform to sense a weight applied to the platform, the load cell comprising a deformable plate with one or more strain gauges arranged to provide an electrical signal representing the weight applied to the platform, and a base supporting the load cell, wherein the deformable plate is movably mounted to the base at only three contact points, the contact points allowing lateral movement of the plate relative to the base when the plate deforms in response to a weight applied to the platform. The weight sensor makes it possible to independently monitor the weight and weight shifting of two people sharing the same bed. The weight sensor is selfcentring when a load is applied off-centre to the platform, which is particularly beneficial when such a weight sensor is used underneath a bed, e.g. under a bed leg or other support member which may not be aligned centrally over the weight sensor. Beneficially the sensor is not unduly affected by minor misalignment of the leg of a bed relative to the load cell.