Wheelchair Tie-Down Tensioning for Excursion Control
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Solution Overview
Problem
Existing vehicle safety systems are inadequate for securing wheeled mobility devices and their occupants during adverse driving scenarios, as they do not account for the independent and dynamic movements of the device and passenger, leading to increased excursions and potential injuries.
Innovation Solution
A comprehensive energy management system that utilizes a computing system with a processor to ascertain adverse driving conditions and trigger appropriate safety devices, such as tensioning and load-limiting technologies, to reduce excursions of the mobility device and its occupant.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If elastic tie-downs are used to secure the wheeled mobility device, then the device can be easily installed and removed, but the tie-downs stretch and allow excessive movement of the device during transit
Solution Approach 1:
The system performs preliminary action by detecting adverse driving conditions (such as crashes or sharp turns) before they result in excessive excursion, and pre-tensions the tie-downs to minimize movement. The processor detects g-force changes and triggers tensioning mechanisms in advance to prevent harmful excursions rather than reacting after they occur.
Solution Approach 2:
The tie-down system transitions from a static elastic configuration to a dynamic controlled system. The retractors can adjust their tension characteristics in real-time based on detected driving conditions, changing from allowing elastic movement to providing rigid constraint when adverse conditions are detected, thus adapting the system's mechanical properties to the operational context.
2Reliability
If the tie-down webbing is locked in place, then the mobility device is securely fixed, but the webbing cannot spool out to accommodate movement during transit
Solution Approach 1:
The retractor mechanism dynamically adjusts between two states: a locked state for securement stability and a spooling state for movement accommodation. The system transitions between these states based on detected adverse driving conditions, allowing the same mechanism to provide both rigid fixation when needed and flexible movement when appropriate.
Solution Approach 2:
The system uses feedback from g-force sensors and processors to monitor the mobility device's movement and tension status. This feedback loop allows the retractor to respond to actual conditions, spooling out webbing when movement is detected and locking when stable conditions return, thus adapting the securement level to the operational context.
3Reliability
If existing vehicle safety systems are used, then ambulatory passengers are protected during crashes, but wheeled mobility device occupants are not adequately secured due to different movement dynamics
Solution Approach 1:
The system applies local quality by implementing safety mechanisms specifically tailored to the unique characteristics of wheeled mobility devices rather than using generic vehicle safety systems. The processor detects adverse conditions and triggers tensioning actions specifically for the mobility device securement system, addressing the local needs of this particular occupant type with customized control logic and response characteristics.
Solution Approach 2:
The system changes operational parameters based on detected conditions, adjusting tension force, response timing, and retractor engagement characteristics to match the specific dynamics of wheeled mobility devices. The processor modifies these parameters in real-time based on g-force data, allowing the same hardware to provide optimized protection for mobility device occupants under varying crash scenarios.
Data Source
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AI summary
A pre/post-tensioning controller system for a wheelchair tie-down and occupant restraint system ("WTORS") will be a comprehensive energy management system for controlling excessive excursions of a wheeled mobility device during various adverse driving scenarios. The system uses multiple pre-tensioning and post-tensioning events during a front, side, or rear impact crash or rollover scenario - and effectively controls excursions by the tensioning of the WTORS equipment at specific and ideal moments. The system also uses tensioning events on the tie-down equipment during a long duration turn or other aggressive maneuvers. The system may also use tensioning events on the occupant restraints. The energy management system can be adapted for use with traditional four-point tie-downs and newer three- and two-point tie-down systems that incorporate fixed or movable bumpers, as well as compressive-type securement systems, and other systems as well, including docking systems.