Motorized Track Battery Control for Powered Stair Chair Safety
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Solution Overview
Problem
Conventional powered stair chairs for patient transport face challenges such as increased system complexity, weight, cost, reliability issues, thermal generation, and reduced motor speed due to redundant hardware and software for battery safety, as well as difficulty in consistent control under varying operation conditions.
Innovation Solution
A patient transport apparatus with a battery system that includes a power output, battery cells, and a controller configured to enable power transmission only when the current draw is below a predefined threshold, along with a track assembly and drive system operable between a current sink mode and an operational mode, featuring a motor and apparatus controller to manage power and movement, ensuring safe and efficient operation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If redundant hardware and software are employed to disconnect the battery system for safety, then battery safety is improved, but system complexity increases
Solution Approach 1:
The patent extracts the battery disconnection function from complex redundant hardware and software systems, implementing it through a simplified controller that monitors current draw and automatically disconnects the battery when thresholds are exceeded. This removes the need for multiple separate safety mechanisms while maintaining battery protection.
Solution Approach 2:
The controller serves multiple functions: it manages motor operation, monitors battery current draw, determines when to disconnect the battery, and controls the drive system. By consolidating these functions into a single multi-functional controller, the patent reduces overall system complexity while maintaining comprehensive safety and operational control.
2Reliability
If redundant hardware and software are employed to disconnect the battery system, then battery safety is improved, but weight increases
Solution Approach 1:
The patent removes unnecessary redundant safety hardware and implements battery protection through a software-based current monitoring and disconnection system in the controller. This significantly reduces the weight compared to hardware-based safety mechanisms while maintaining equivalent or superior safety performance.
3Reliability
If redundant hardware and software are employed for battery safety, then battery safety is improved, but motor speed reduces
Solution Approach 1:
The controller dynamically adjusts its operation based on real-time current draw monitoring. It allows the motor to operate at full speed when current is within safe limits and only intervenes to disconnect the battery when current exceeds thresholds. This dynamic approach maintains optimal motor performance while ensuring battery safety, unlike static redundant systems that may continuously limit speed.
4Reliability
If redundant hardware and software are employed for battery safety, then battery safety is improved, but thermal generation increases
Solution Approach 1:
The patent converts the potentially harmful effect of current draw into a useful monitoring parameter. By continuously measuring current and using it to trigger battery disconnection when thresholds are exceeded, the system prevents overheating and thermal damage before they occur, transforming what could be a safety hazard into an early warning signal.
5Reliability
If redundant hardware and software are employed for battery safety, then battery safety is improved, but product efficiency reduces
Solution Approach 1:
The controller autonomously monitors battery current draw and automatically disconnects the battery when safety thresholds are exceeded, without requiring external intervention or complex safety systems. This self-service approach maintains battery safety while minimizing efficiency losses associated with redundant hardware and software overhead.
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 enhances battery safety, reduces system complexity and weight, improves motor speed, and provides consistent control, addressing the challenges faced by conventional powered stair chairs.
Implementation Method 1
a motor disposed in rotational communication with the track assembly to control movement of the patient transport apparatus along stairs
Implementation Method 2
a battery system coupled to the support structure, the battery system including: a power output, one or more battery cells configurable for power transmission
Data Source
AI summary
A patient transport apparatus including a battery system is provided. The battery system includes a battery controller configured to enable power transmission from one or more battery cells to a power output in response to power draw across the power output being below a predefined current threshold. A track assembly, a drive system including a motor disposed in rotational communication with the track assembly to control movement of the patient transport apparatus, and an apparatus controller disposed in communication with the motor and the battery system are provided. The apparatus controller is configured to monitor the power transmission from the battery and to operate the drive system in a current sink mode causing the battery to interrupt power supply upon determining the input current of the battery is greater than the predefined current threshold by comparing the input current of the battery to the predefined current threshold.