Patient Support Lift Systems With Dynamic Load-Cell Alignment
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Solution Overview
Problem
Conventional patient support apparatuses face inaccuracies in weight and position measurement when the patient is positioned in Trendelenburg positions due to the arrangement of load cells.
Innovation Solution
A patient support apparatus with a lift system that includes independent head and foot end lifts, allowing the support frame to be placed in Trendelenburg positions, and load cells coupled to these lifts to accurately measure the load while accommodating frame movement.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If load cells are arranged in a conventional fixed configuration, then the structure is simple and stable, but measurement accuracy deteriorates when the patient is positioned in Trendelenburg positions
Solution Approach 1:
The load cell arrangement is made dynamic by coupling them to independently operable lifts that can adjust their positions. The lifts include guided bodies that move along guides, allowing the load cells to reposition themselves relative to the support frame. This dynamic configuration enables accurate load measurement in Trendelenburg positions while maintaining a relatively simple overall structure through modular design.
2Adaptability or versatility
If the support frame is made rigid and fixed, then structural stability is improved, but the ability to achieve Trendelenburg positions deteriorates
Solution Approach 1:
The support frame system is segmented into multiple independent components: the base, the support frame, and independently operable first and second lifts. Each lift can be controlled separately to achieve Trendelenburg positions, providing adaptability. The modular segmented structure maintains stability through rigid connections within each module while allowing relative movement between modules.
3Measurement precision
If load cells are fixed relative to the support frame, then the structure is simpler, but load transmission accuracy deteriorates during frame movement
Solution Approach 1:
The lifts serve as intermediary elements between the support frame and the load cells. The load cells are coupled to the lifts rather than directly to the support frame, allowing them to maintain accurate relative positioning during frame movement. The guided bodies on the lifts act as intermediaries that transmit load accurately while accommodating the dynamic positioning requirements for Trendelenburg configurations.
Data Source
AI summary
A patient support apparatus includes a base and a support frame. A lift system operates to lift and lower the support frame relative to the base. The lift system includes a first lift and a second lift. The first lift and the second lift are independently operable to place the support frame in one or more Trendelenburg positions. A plurality of load cells acts between the lifts and the support frame such that a load on the support frame is transmitted to the plurality of load cells to measure the load. The first lift includes a guided body arranged to move longitudinally relative to the base in response to operation of the second lift to move the support frame to the one or more Trendelenburg positions.