Load Cell Calibration via Virtual Symbols
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Solution Overview
Problem
Existing patient support apparatuses with weight sensors, such as load cells, face challenges in maintaining consistent reliability and accuracy of weight measurements due to the complexity and cost of calibration, which can lead to human error in entering calibration values.
Innovation Solution
A patient support apparatus with a load cell system that uses calibration reference symbols to simplify the calibration process. The system includes a user interface for receiving virtual symbols corresponding to calibration reference symbols, and a controller that stores calibration values, initiates calibration, determines representative calibration values, and calibrates the load cell parameters based on these values.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If manual entry of calibration values is used, then calibration can be performed, but human error increases leading to inaccurate measurements
Solution Approach 1:
The load cell performs self-calibration by automatically entering its own calibration values into the controller through an interface, eliminating the need for manual technician input. The calibration values are transmitted automatically from the load cell to the controller, ensuring accuracy without human intervention.
Solution Approach 2:
The manual mechanical process of entering calibration values via keyboard or switch is replaced with an automatic electronic data transmission system. The calibration values are electronically transferred from the load cell to the controller, substituting the manual entry mechanism with an automated electronic interface.
2Measurement precision
If complex calibration procedures are used, then measurement accuracy can be maintained, but cost and complexity increase
Solution Approach 1:
The complex manual calibration procedure is extracted and replaced with a simplified automatic process. Only the essential calibration data transmission remains, while the complex manual entry and verification steps are removed. The system extracts only the necessary calibration information from the load cell and inputs it directly.
Solution Approach 2:
The calibration process changes from manual parameter input to automatic parameter transmission. The calibration values are automatically transmitted from the load cell to the controller, changing the process from a complex manual procedure to a simple automated data transfer operation.
3Manufacturing precision
If multiple calibration values with significant figures are entered manually, then calibration precision can be achieved, but error probability increases
Solution Approach 1:
The load cell automatically inputs its own calibration values into the controller without human assistance. The precision calibration values are transmitted directly from the load cell's internal storage to the controller, eliminating the risk of human error in data entry while maintaining full precision.
Solution Approach 2:
The calibration values are copied directly from the load cell's internal storage to the controller's memory through an automatic interface. This direct copying process preserves the exact precision of the calibration values without the degradation that occurs during manual transcription.
Data Source
AI summary
A patient support apparatus includes a load cell, disposed between a base and a litter, that is configured to generate an output representative of a load acting on the patient support surface. The load cell is associated with a calibration reference symbol assigned to the load cell to define a calibration value for a parameter of the load cell. A user interface is configured to receive user input of a virtual symbol corresponding to the calibration reference symbol. A controller is configured to store a plurality of calibration reference symbols and a plurality of representative calibration values each associated with one of the plurality of calibration reference symbols, initiate a calibration procedure, determine a representative calibration value for each calibration reference symbol, calibrate the parameter of the load cell based on the representative calibration value determined based on the virtual symbol, and determine weight acting on the litter.