Escalator Braking Distance Measurement Using Optical and Acoustic Sync
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Solution Overview
Problem
Existing methods for measuring the braking distance of escalators and moving walkways do not accurately reflect the actual braking behavior due to the inclusion of reaction times of sensors and brakes, leading to inaccurate compliance with safety standards.
Innovation Solution
A method using a braking distance measuring device with an optical sensor and acoustic sensor, synchronized to record the relative motion and brake operating noises, allowing for precise calculation of braking distance and deceleration, and optionally utilizing image processing for automated analysis.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the optical sensor is used to detect the measuring scale and trigger braking, then the braking distance can be measured according to safety standards, but the measurement includes reaction times of sensors and control systems which reduces measurement precision
Solution Approach 1:
The measurement process is segmented into distinct phases: the total stopping distance measured by the optical sensor is divided into the reaction distance (covering sensor detection, control signal transmission, and brake activation) and the actual braking distance (from brake engagement to complete stop). This segmentation allows separate measurement and evaluation of each phase, enabling precise determination of actual braking behavior while maintaining compliance with safety standards that require measurement from stop signal to complete stop.
2Reliability
If the brake is activated immediately upon detecting the measuring scale, then the braking distance measurement complies with standards, but the reaction time of the brake system is included in the measurement reducing accuracy
Solution Approach 1:
The system performs preliminary measurement of the reaction distance by detecting when the optical sensor first detects the measuring scale and when the brake actually engages (through secondary detection means). This preliminary action quantifies the reaction time distance, which is then subtracted from the total stopping distance to isolate the actual braking distance. This approach maintains standard compliance while eliminating the reaction time component from the final braking performance evaluation.
3Reliability
If the measurement system includes all components from stop signal to complete stop, then it follows safety standards, but it records periods without braking torque including control system reaction times
Solution Approach 1:
The measurement system extracts and separates the reaction time component from the total stopping distance measurement. By using additional detection means to identify the exact moment of brake engagement, the system extracts the reaction distance portion and removes it from the calculation of actual braking distance. This extraction allows the system to adhere to safety standards that require measurement from stop signal while eliminating the non-braking time periods from the final evaluation metric.
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
Provides precise measurement of actual braking behavior, enabling adjustment of brakes to meet safety standards and diagnosing brake conditions, reducing the time and effort required for compliance checks.
Implementation Method 1
an optical sensor which is configured to detect the relative motion between the marker and the measuring scale
Data Source
Figure 1~2
Figure 3~4
Figure 5A~5C
AI summary
The invention relates to a method for measuring the braking distance (LB) and to a braking distance measuring device (30) for carrying out the method on an escalator (1) or a moving walkway. The braking distance measuring device (30) has at least one trigger device (45) which can be connected to the controller (14) of the escalator (1) or the moving walkway, an optically detectable linear measuring scale (31), an optical sensor (35), and an acoustic sensor (36). In order to allow a more precise measurement of the braking distance (LB), a braking process is optically and acoustically recorded as an image sequence (60) with a graphically displayed audio track (65). The start point (68) and the end position (69) of braking operation noises (51) recorded on the audio track (65) can be precisely assigned to the images (62, 63) of the image sequence (60), and the braking distance (LB) is ascertained from the determined images (62, 63) by comparing the different positions of a marking (53) with the measuring scale (31).