Patient Weight Measurement via Drive Train Oscillation

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Solution Overview

Problem

Existing methods for determining a patient's weight on a patient positioning device are imprecise, especially for patients who cannot stand or are unconscious, and often rely on estimating weight through power consumption or force sensors, lacking a reliable and accurate alternative.

Innovation Solution

A method utilizing an elastic component in the drive train of a patient positioning device to create a mass-spring system, where the patient's weight is determined by analyzing the oscillation frequency induced by a motorized movement, allowing for precise weight calculation through motor current analysis.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If force sensors are mounted on the table-foot to determine patient weight, then weight measurement capability is provided, but device complexity and cost increase

Engineering Contradiction:

Improvepatient weight determinationVSAvoiddevice complexity

Core Design Contradiction:

Measurement precisionVSDevice complexity

Solution Approach 1:

The existing motorized drive unit and elastic drive train elements serve dual purposes: both moving the tabletop and measuring patient weight through oscillation analysis. The system uses its own operational components for measurement without requiring separate dedicated sensors or weighing mechanisms.

Inventive Principle:

Principle #25Self-service

Solution Approach 2:

The patent replaces direct mechanical force sensing with a dynamic oscillation-based measurement approach. Instead of using force sensors to directly measure weight, the system induces oscillations and analyzes the frequency characteristics to determine patient weight, substituting a mechanical sensing system with a dynamic analysis system.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

2Ease of operation

If power consumption of the lift drive is used to estimate patient weight, then weight estimation is possible, but measurement precision deteriorates

Engineering Contradiction:

Improveweight determination capabilityVSAvoidweight estimation accuracy

Core Design Contradiction:

Ease of operationVSMeasurement precision

Solution Approach 1:

The patent deliberately induces mechanical oscillations in the tabletop system and measures the oscillation frequency to determine patient weight. The elastic drive train element acts as a spring in a mass-spring system, where the oscillation frequency directly correlates with the total mass (tabletop + patient), providing accurate weight measurement through vibration analysis.

Inventive Principle:

Principle #18Mechanical vibration

3Measurement precision

If external personal scales are used to weigh patients, then accurate weight measurement is achieved, but ease of operation and patient comfort deteriorate for unable-to-stand patients

Engineering Contradiction:

Improveweight measurement accuracyVSAvoidpatient positioning requirement

Core Design Contradiction:

Measurement precisionVSEase of operation

Solution Approach 1:

The patient positioning device is designed to perform multiple functions: positioning the patient during medical procedures and simultaneously determining patient weight. The weight measurement function is integrated into the positioning system itself, allowing both functions to be performed without requiring the patient to be moved to or from external weighing equipment.

Inventive Principle:

Principle #6Universality (Multi-functionality)

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 accurate and simple determination of a patient's weight by correlating motor current amplitude and frequency with physical characteristics, providing better precision than existing methods and eliminating the need for external weighing.

Implementation Method 1

A motorized movement of the tabletop along at least one predeterminable axis sets the tabletop in an oscillation by an elastic drive train element, and the patient's weight is determined from the determined oscillation frequency

Methodology Applied

Scientific EffectOscillation: Vibration

Implementation Method 2

Patient, tabletop and drive train form a mass-spring system that is capable of oscillation, the frequency of which is indirectly proportional to the patient's mass

Methodology Applied

Scientific EffectMass-spring system: Spring

Implementation Method 3

The invention also claims a method for automatically determining a patient's weight of a patient lying on the tabletop of a patient positioning device. A motorized movement of the tabletop along at least one predeterminable axis sets the tabletop in an oscillation by an elastic drive train element

Methodology Applied

Scientific EffectOscillation compensation: Damping

Data Source

PatentUS10806410B2Method, arrangement, computer program product and computer-readable medium for automatically determining patient weight with a patient positioning device

Publication Date: 2020.10.20 SIEMENS HEALTHINEERS AG

AI summary

A method automatically determines a weight of a patient lying on a tabletop of a patient positioning device. A motorized movement of the tabletop along at least one predeterminable axis sets the tabletop in an oscillation via an elastic drive train element, and the patient's weight is determined from a determined oscillation frequency. Therefore, the weight of a patient lying on a patient positioning device can be determined in a simple manner.