Accelerometer Calibration Using Load Cell Data
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Patient weight measurement accuracy is compromised when patient support apparatuses are articulated or positioned other than horizontally flat, due to shifting center of gravity affecting load cell readings, and existing accelerometer recalibration methods are error-prone and require specific environments.
Innovation Solution
Automated systems and methods for calibrating accelerometers using load cell outputs at different angles, allowing for local recalibration without specific environmental requirements, by determining and correcting for gravitational variations and sensor drift.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If the patient support apparatus is articulated or positioned other than horizontally flat, then the patient support system can accommodate different patient positions and needs, but the load cell measurements become inaccurate due to shifting center of gravity
Solution Approach 1:
The system changes the parameter being measured from direct weight to a combination of load cell output and articulation angle. By measuring both the load on the support surface and the angle of articulation, the system can calculate the actual patient weight independent of position, resolving the contradiction between adaptability and measurement precision.
2Ease of operation
If traditional accelerometer calibration methods are used outside manufacturing facilities, then recalibration can be performed in various locations, but the process becomes error-prone and complex requiring particular preconfigured environments
Solution Approach 1:
The load cell serves as an intermediary reference standard for accelerometer calibration. Instead of requiring complex environmental setups or specialized equipment, the system uses the load cell's accurate weight measurements as a mediator to calibrate the accelerometer in any location, simplifying the process while maintaining reliability.
3Ease of manufacture
If accelerometers are calibrated at manufacturing time only, then the calibration process is simple and controlled, but the accelerometers experience drift and parameter variations over time leading to reduced accuracy
Solution Approach 1:
The system performs preliminary calibration actions using the load cell as a reference standard. By establishing a calibration relationship between the load cell and accelerometer that can be reapplied over time, the system maintains manufacturing simplicity while enabling periodic recalibration to counteract drift and maintain 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
Enables accurate patient weight measurement independent of articulation position and reduces errors associated with gravitational variations and sensor drift, improving measurement precision and simplifying recalibration processes.
Implementation Method 1
Accelerometers, or tilt sensors that incorporate an accelerometer, can be used to provide an effective way to measure the inclination in the patient's position
Implementation Method 2
One difficulty with determining the patient's weight occurs when the patient support apparatus is articulated or at positions other than a horizontally flat base position, at which load cells are usually calibrated
Data Source
AI summary
An automated system and methods are provided for calibrating an accelerometer of a patient support apparatus using a load cell. The patient support apparatus includes a litter frame and a deck supported by the litter frame, movable between various angled positions. A patient support surface is arranged on the deck and configured to support a patient thereon. The patient support surface has at least one region configured to be disposed at an angular position. A load cell is provided, configured to generate load data including first and second load outputs detected at first and second trend angles with respect to a horizontal plane. An accelerometer is provided, configured to generate angle data including first and second angle outputs representative of the trend angles. A controller in communication with the load cell and the accelerometer determines an error in the angle data and calibrates the accelerometer.