Accelerometer-Based Occupant Detection in Person Support Apparatuses
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Solution Overview
Problem
Existing person support apparatuses, such as beds and cots, face challenges in accurately detecting occupant presence, exit detection, weight measurement, and filtering out noise and vibrations, which affects the reliability of exit detection systems and weight measurement processes.
Innovation Solution
Incorporating accelerometers and force sensors into the support apparatus to detect and assess impacts, estimate occupant location and movement, and filter out unwanted signals, while also automatically managing the exit detection system and scale functionality, including automatic arming and zeroing of weight readings.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If accelerometers are added to detect occupant presence and movement, then exit detection accuracy is improved, but device complexity increases
Solution Approach 1:
The patent combines multiple sensor functions into a single accelerometer component. The accelerometer simultaneously detects occupant presence, movement patterns, exit events, and impact forces, replacing what would traditionally require multiple separate sensors. This merging reduces overall system complexity while maintaining comprehensive monitoring capabilities.
Solution Approach 2:
The accelerometer is designed to perform multiple functions: detecting static presence through vibration analysis, monitoring dynamic movement for exit detection, measuring impact forces for safety monitoring, and providing data for weight estimation. This multi-functionality eliminates the need for separate dedicated sensors for each function.
2Reliability
If multiple sensors are used to detect impacts and movements, then reliability is improved, but device complexity increases
Solution Approach 1:
The accelerometer acts as an intermediary sensor that indirectly measures various physical quantities through acceleration data. Instead of using separate direct sensors for presence, movement, and impact detection, the single accelerometer processes different aspects of acceleration to provide multiple detection functions, reducing sensor count while maintaining reliability.
3Ease of manufacture
If accelerometers are positioned below the cushioning structure, then ease of installation is improved, but measurement precision may worsen
Solution Approach 1:
The patent extracts the accelerometer from the traditional weight sensor position and places it in the litter frame below the cushioning structure. This separation allows the accelerometer to focus on detecting dynamic acceleration events while the cushioning structure handles static weight support, optimizing both installation ease and measurement precision for dynamic events.
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
Enhances the accuracy of exit detection and weight measurement by filtering noise and vibrations, improving the reliability of the system in detecting occupant presence and movement, and preventing potential damage to components.
Implementation Method 1
one or more accelerometers that are used for one or more of the following purposes: to detect and assess impacts of the person support apparatus; to estimate a location and/or detect movement of an occupant
Data Source
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AI summary
A person support apparatus, such as a bed, stretcher, cot, recliner, or the like, includes a support surface adapted to support a person, a litter, an accelerometer positioned below the support surface, and a controller that processes signals from the accelerometer to detect the presence or absence of a person on the support surface. In some embodiments, the controller also receives signals from a plurality of force sensors and uses them in combination with the accelerometer outputs to determine if the person has exited the person support apparatus. The controller may also be adapted to use outputs from the accelerometer to detect an impact against the person support apparatus, compare a magnitude of the detected impact with a threshold, and, if the threshold is exceeded, to issue a warning indicating potential damage to one or more of the plurality of force sensors.