Pressure-Sensitive Barrier for Wheelchair Lift Safety
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Solution Overview
Problem
Existing sensor technologies, such as switch-mats, ultrasonic sensors, or infrared sensors, are not well-suited to comply with new Federal Motor Vehicle Safety Standards due to physical design constraints, weight, maintenance requirements, and precision issues, making it difficult to prevent wheelchair lift barriers from operating when occupied by a passenger or mobility aid.
Innovation Solution
A wheelchair lift with pressure-sensitive moveable barriers that use an actuator to prevent operation when an object is present, featuring a biasing device that absorbs movement when loaded, ensuring the barrier does not transition into a blocking position if occupied, thus preventing potential injury.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If switch-mat technology is used to detect passengers on the lift platform, then passenger detection capability is improved, but the weight and power transmission requirements increase due to the thickness and mass of the switch-mats
Solution Approach 1:
The patent replaces mechanical switch-mat technology with a pressure-sensitive material integrated into the barrier structure itself. The barrier incorporates a pressure-sensitive layer that directly detects passenger presence through pressure changes, eliminating the need for separate mechanical switch-mats and reducing overall weight while maintaining detection reliability
Solution Approach 2:
The pressure-sensitive detection function is merged directly into the barrier structure. The barrier serves dual purposes: it acts as both the safety barrier and the passenger detection mechanism through the integrated pressure-sensitive material, eliminating the need for separate detection components
2Reliability
If switch-mats are added to the outer barrier and inner roll stop, then passenger detection is improved, but the device complexity and manufacturing difficulty increase due to integration constraints
Solution Approach 1:
The pressure-sensitive detection function is merged directly into the barrier structure. The barrier serves dual purposes: it acts as both the safety barrier and the passenger detection mechanism through the integrated pressure-sensitive material, eliminating the need for separate detection components
Solution Approach 2:
The barrier is designed with multi-functionality, serving both as a physical safety barrier and as a passenger detection system through the integrated pressure-sensitive material. This universal design simplifies manufacturing by eliminating the need to integrate separate sensor systems into the barrier structure
3Reliability
If ultrasonic or infrared sensors are used for passenger detection, then detection capability is improved, but maintenance requirements increase due to the need for clean sensor lenses in the dirty transit environment
Solution Approach 1:
The patent replaces optical sensor systems (ultrasonic or infrared) with a pressure-sensitive material system. This mechanical/physical detection method has no lenses or optical components that require cleaning or maintenance, eliminating the maintenance burden associated with optical sensors in dirty transit environments
Solution Approach 2:
The pressure-sensitive material system requires no external maintenance or cleaning. It automatically detects passenger presence through pressure changes and continues to function reliably in dirty environments without requiring preventive maintenance of lenses or optical components
4Reliability
If traditional sensors are used to prevent barrier operation when occupied, then safety is improved, but the barriers may still operate erroneously due to imprecise sensing patterns
Solution Approach 1:
The pressure-sensitive material is distributed throughout the barrier structure, creating multiple local detection zones. Each area of the barrier can independently detect pressure changes, providing precise and reliable detection of passenger presence regardless of where the passenger is positioned on the barrier
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
The solution effectively prevents the wheelchair lift barriers from operating when occupied, enhancing safety by ensuring the barriers remain in a position that allows safe loading and unloading, while reducing weight and maintenance concerns associated with traditional sensor technologies.
Implementation Method 1
the actuator is adapted to apply an actuation force upon the barrier to move the barrier from the access position to the blocking position
Implementation Method 2
When the barrier is in a loaded state, the actuation force causes the actuator to move in a second direction a predetermined amount without causing substantial movement of the barrier
Data Source
AI summary
A wheelchair lift (100) for a vehicle having a barrier (128) moveable between an access position and a blocking position. The wheelchair lift includes an actuator (152) coupled to the barrier, the actuator adapted to apply an actuation force upon the barrier to move the barrier from the access position to the blocking position. When the barrier is in an unloaded state, the actuation force causes the actuator to move in a first direction resulting in the barrier moving from the access position to the blocking position. When the barrier is in a loaded state, the actuation force causes the actuator to move in a second direction a predetermined amount without causing substantial movement of the barrier.