Auxiliary Wheel for Patient Support Maneuverability
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Solution Overview
Problem
Patient support apparatus, such as hospital beds and stretchers, face difficulties in steering and maneuverability due to unpredictable motion caused by castors not maintaining a fixed orientation, requiring significant effort and often two people to operate effectively.
Innovation Solution
A deployable auxiliary wheel located at the midpoint of the apparatus, controlled by a rotatable shaft and actuator, which can be deployed and retracted to improve steering and maneuverability, with sensors and dampening mechanisms to maintain contact with the floor and absorb surface irregularities.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If castors are used at four corners of the apparatus, then the apparatus can move freely, but the axes of the castors are not maintained in a fixed relationship or orientation, causing unpredictable motion
Solution Approach 1:
The apparatus divides its wheel system into two functional segments: four corner castors for support and basic mobility, plus a fifth auxiliary wheel at the center for directional control. This segmentation allows the castors to swivel freely for adaptability while the auxiliary wheel provides the fixed pivot axis needed for predictable motion along straight paths.
Solution Approach 2:
The auxiliary wheel acts as an intermediary element between the operator and the castor system. By providing a fixed pivot axis at the center, it mediates the turning motion and ensures the apparatus moves predictably in the desired direction, overcoming the instability caused by multiple swiveling castors.
2Ease of operation
If mechanisms are added to brake or lock castors, then handling is facilitated, but the physical effort required to maneuver the apparatus remains significant
Solution Approach 1:
The auxiliary wheel assembly is designed to be dynamically deployable rather than permanently fixed. The wheel can be lowered to engage with the floor when directional control is needed, and raised when not needed, allowing the system to adapt its characteristics based on operational requirements and reducing unnecessary friction.
Solution Approach 2:
The auxiliary wheel assembly includes a spring mechanism that automatically lowers the wheel when the assembly is released, without requiring manual intervention. The spring stores potential energy during retraction and automatically converts it to kinetic energy to lower the wheel, making the system self-regulating and reducing the force needed by the operator.
3Reliability
If two people are required to steer the apparatus, then casting motion control is improved, but operational efficiency is reduced
Solution Approach 1:
The auxiliary wheel is positioned at the center of the apparatus, which is the optimal pivot point for turning. This preliminary placement of the control element at the geometric center allows a single operator to effectively control the apparatus's direction, eliminating the need for a second person and improving operational efficiency while maintaining reliable motion control.
4Reliability
If an auxiliary wheel is deployed at the midpoint of the apparatus, then tracking and maneuverability are improved, but the device complexity increases
Solution Approach 1:
The auxiliary wheel assembly is nested within the apparatus frame structure. The wheel, spring mechanism, and mounting components are compactly arranged in a space-efficient configuration that integrates with the existing frame, minimizing the increase in overall device complexity while providing the needed functional improvement.
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 ability to control and predict the path of motion, reducing the effort required to maneuver the apparatus, allowing single-person operation by providing a fixed pivot axis and improved stability over uneven surfaces.
Implementation Method 1
A spring may be provided to provide a dampening effect when the auxiliary wheel encounters a raised surface and to urge the auxiliary wheel into contact with the supporting surface when the auxiliary wheel encounters a lowered surface.
Data Source
AI summary
A patient support has caster devices supporting a frame for movement in relation to a supporting surface. A lift supports an auxiliary wheel in relation to the frame. A shaft may be rotatable to drive the lift to move the auxiliary wheel between a deployed position and a retracted position. The shaft may rotate to control deployment and retraction of the auxiliary wheel. A sensor may control deployment and retraction of the auxiliary wheel. An element may provide a dampening effect when the auxiliary wheel encounters a raised surface and urge the auxiliary wheel into contact with the supporting surface when the auxiliary wheel encounters a lowered surface.