Load Sensor Configurations for Caster Assemblies
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Solution Overview
Problem
Conventional patient support apparatuses face challenges in accurately measuring load due to tilting of the support surface, which causes load paths to circumvent sensors, leading to inaccurate readings, especially when patients move or adjust their posture.
Innovation Solution
Integrating load sensors with the caster assemblies, allowing the load path to pass through the sensors, ensuring accurate measurements even when the support surface is tilted, and enabling the sensors to capture the load effectively without the need for additional support structures.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If sensors are placed by the support surface, then the support surface can be positioned freely for patient comfort, but the load readings become inaccurate when the support surface is tilted
Solution Approach 1:
The patent inverts the conventional sensor placement location from the support surface to the caster assembly. By placing the load sensor at the caster assembly where the load path is guaranteed to pass through, the system eliminates the need to maintain horizontal positioning for accurate measurements, thus resolving the contradiction between positioning freedom and measurement accuracy.
2Device complexity
If sensors are placed by the support surface, then the structure remains simple, but the load path may bypass the sensors when patients move or adjust posture
Solution Approach 1:
The patent extracts the load sensor from the support surface structure and relocates it to the caster assembly. This extraction ensures that the sensor is positioned at a critical point in the load path where all forces must pass through, eliminating the reliability issues caused by patients moving or adjusting posture while maintaining structural simplicity.
3Measurement precision
If the support surface is kept horizontal to ensure accurate readings, then measurement accuracy improves, but patient convenience and health-related movement are restricted
Solution Approach 1:
The patent inverts the approach by not controlling the support surface orientation for accurate readings, but rather placing the sensor at the caster assembly where accurate readings are obtained regardless of support surface orientation. This enables full patient position adaptability while maintaining measurement precision.
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
This configuration provides accurate load readings regardless of the support surface's orientation, allowing for free tilting and movement while ensuring that the load path is consistently detected, enhancing the reliability of load measurements.
Implementation Method 1
the load sensor is integrated with the caster assembly and is configured to measure an applied load
Data Source
AI summary
A patient support apparatus comprises a base supported by caster assemblies with each caster assembly comprising a stem, a caster wheel, and a caster wheel axle. A patient support surface is coupled to the base and is configured to receive a load. One or more load sensors are integrated with at least one of the stem, the caster wheel, or the caster wheel axle for measuring the load. One or more of the caster assemblies can be coupled to a steering motor, which controls orientation of the caster assembly. A controller can control the steering motors based on analyzing the measurements of the load sensor. The load sensors can produce measurements indicative of both vertical load and non-vertical load applied to the caster assembly. The controller can also analyze the measurements of the load sensor to determine the load received by the patient support surface by negating the non-vertical load.