Load Cell Motion Characterization in Hospital Beds
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Solution Overview
Problem
Existing patient support apparatuses face challenges in accurately characterizing patient motion due to external influences and transient forces, which complicate the detection of patient movement and motion, leading to compromised weight distribution measurements and inaccurate predictive analysis.
Innovation Solution
A patient support apparatus equipped with a control system that processes signals from multiple load cells to distinguish between patient motion and non-patient motion artifacts, calculating work done by the patient in various directions and updating a patient profile to reflect the characterization of motion, thereby improving the accuracy of motion characterization and predictive analysis.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Difficulty of detecting and measuring
If load cells are used to measure patient weight and detect movement, then patient motion detection capability is improved, but measurement precision deteriorates due to external influences and transient forces
Solution Approach 1:
The patent segments the motion detection function into two independent components: (1) a scale system with load cells that measures only vertical weight changes, and (2) a separate motion detection system that processes transient force changes from multiple load cells to detect lateral and rotational movements. This segmentation allows each system to optimize for its specific function without interference from external influences affecting the other.
Solution Approach 2:
The patent introduces an intermediary processing layer that receives raw force data from multiple load cells and applies algorithms to distinguish patient motion from external transient forces. This intermediary layer filters out harmful factors such as equipment additions or caregiver pressure by analyzing force distribution patterns across multiple sensors, thereby preserving measurement precision while maintaining motion detection capability.
2Loss of information
If motion algorithms rely on weight distribution changes to determine patient location, then patient position tracking is improved, but reliability deteriorates due to transient external forces
Solution Approach 1:
The patent implements feedback mechanisms where the motion detection system continuously monitors force distribution patterns from multiple load cells and adjusts its algorithms based on detected patterns. When transient external forces are detected, the system learns to distinguish these from genuine patient movements, improving reliability over time while maintaining accurate position tracking.
Solution Approach 2:
The patent makes the load cell system multi-functional by using the same sensors for both weight measurement and motion detection, but with separate processing pathways. The scale system handles vertical weight changes while the motion detection system processes lateral and rotational movements, allowing both functions to operate reliably without interfering with each other.
3Difficulty of detecting and measuring
If the system monitors all weight changes on the frame, then comprehensive motion detection is improved, but measurement precision deteriorates due to equipment additions and caregiver pressure
Solution Approach 1:
The patent segments the monitoring function into distinct channels: weight measurement channel that captures only vertical forces, and motion detection channel that captures transient force changes from multiple sensors. This segmentation allows comprehensive motion monitoring without compromising the precision of weight measurements, as each channel processes only relevant data.
Solution Approach 2:
The patent extracts the harmful transient force components from the overall weight measurement by using separate motion detection algorithms that specifically target lateral and rotational movements. This extraction removes the confounding influence of external forces such as equipment additions or caregiver pressure, preserving the accuracy of patient weight measurements while maintaining comprehensive motion detection.
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 solution enables precise characterization of patient motion, distinguishing between different types of movements and disregarding non-patient motion artifacts, leading to enhanced predictive analysis and improved monitoring of patient conditions and actions.
Implementation Method 1
a plurality of load cells positioned on the first frame... the load cells measure the combined load of the patient and equipment
Data Source
AI summary
A patient support apparatus comprise a first frame, a plurality of load cells positioned on the first frame, a second frame, and a control system. The control system includes a controller, the controller is operable to receive a separate signal from each of the plurality of load cells, process the signals to identify, based on transient changes in the forces measured by each of the plurality of load cells, motion of the patient, classify the motion of the patient, and, based on the classification, update a patient profile in a patient record to reflect the characterization of the patient motion.