Stairlift Carriage Levelling via Accelerometer Feedback
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Solution Overview
Problem
Existing stair lift systems face challenges in maintaining seat level and optimal speed along complex rail paths, requiring pre-programming, multiple sensors, and memory storage, which increases complexity, cost, and risk of data corruption.
Innovation Solution
A lift system utilizing a single high-sensitivity accelerometer for real-time levelling control, coupled with a levelling motor and mechanism, allows the seat to maintain a predetermined orientation without pre-programming, using filtered accelerometer signals to adjust the seat's inclination and control speed based on rail slope and curvature.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If pre-programming with multiple fixed speeds is used for each rail section, then speed control along complex rail paths is achieved, but system complexity and cost increase due to programming requirements and memory storage
Solution Approach 1:
The patent replaces the mechanical/electronic system of pre-programmed speed tables and memory storage with a sensor-based feedback system. Accelerometers detect rail slope and curvature in real-time, and the control means automatically adjusts speed based on these physical measurements, eliminating the need for programmed speed values and memory storage.
Solution Approach 2:
The system uses the rail's own geometric properties (slope and curvature) as detected by accelerometers to automatically determine the appropriate speed. The rail itself provides the information needed for control through its physical configuration, eliminating the need for external programming or stored data.
2Speed
If memory means are used to store programmed speeds, then speed control is maintained, but reliability decreases due to potential data corruption or loss over time
Solution Approach 1:
The patent replaces the vulnerable electronic memory storage system with a physical sensor-based system. Instead of storing speed data electronically (which can corrupt), the system continuously measures rail geometry with accelerometers and derives speed requirements from these real-time physical measurements, eliminating data corruption risks.
Solution Approach 2:
The system performs real-time detection of rail conditions before speed adjustment is needed. The accelerometers continuously monitor rail slope and curvature ahead of the carriage, allowing the control means to proactively adjust speed based on upcoming rail geometry rather than relying on pre-stored speed data.
3Measurement precision
If multiple sensors are used for levelling control, then orientation accuracy is improved, but device complexity and cost increase
Solution Approach 1:
The patent makes the accelerometer system multi-functional by using the same accelerometers that detect rail slope for both speed control and seat levelling functions. The levelling mechanism uses the slope information already captured by the accelerometers, eliminating the need for separate level-specific sensors and reducing overall system complexity.
Solution Approach 2:
The patent combines the speed control and levelling control functions into a single integrated system. Both functions use the same accelerometer data regarding rail slope and curvature, merging what could have been separate sensor systems into one unified control approach that reduces complexity while maintaining accuracy.
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
Enables real-time levelling and speed control responsive to rail changes, reducing system complexity, eliminating the need for pre-programming and memory storage, while ensuring accurate and reliable operation.
Implementation Method 1
a first accelerometer arranged to provide an output signal indicative of an inclination of the carriage assembly with respect to vertical
Implementation Method 2
a levelling mechanism operable to adjust an orientation of the carriage assembly with respect to the rail
Data Source
Figure 1
Figure 2~3
Figure 4~5
AI summary
A lift system comprises: a rail (1): a carriage assembly (2)comprising a seat or platform (21) for supporting a person to be conveyed along the rail; and drive means (31) coupled to the carriage assembly and adapted to engage the rail and drive the carriage assembly along the rail. In one aspect the system comprises levelling means (41) operable to adjust an orientation of the carriage assembly with respect to the rail, and the carriage assembly comprises: an accelerometer (22a) arranged to provide an output signal indicative of an inclination of the seat or platform with respect to a horizontal plane HP; and control means (23) arranged to receive the output signal and control the levelling means to adjust the orientation to maintain the inclination of the seat or platform substantially at a predetermined value or within a predetermined range. In another aspect the system comprises control means arranged to control the drive means; slope indicating means (5); and curvature indicating means (6), and the control means is adapted to use signals indicative of slope or curvature to control a speed at which the drive means drives the carriage assembly along the rail according to position along the rail.