Elevator Car Positioning with Bi-Stable Gray Code Sensors

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Solution Overview

Problem

Existing methods for determining elevator car position are prone to system noise, leading to false clocking signals and are sub-optimal in the number of sense elements used, particularly when employing binary codes for position identification.

Innovation Solution

A system utilizing bi-stable sensors that travel with the elevator car and sense elements positioned along its path, where the sensors assume different states to generate a gray code zone code, indicating the car's position, thereby improving accuracy and reducing noise interference.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If three sensors and a fourth clock input sensor are used to determine elevator car position, then position detection capability is provided, but system noise causes false clocking signals reducing reliability

Engineering Contradiction:

Improveposition detection reliabilityVSAvoidsystem noise interference

Core Design Contradiction:

ReliabilityVSObject-affected harmful factors

Solution Approach 1:

The patent removes the separate clock input sensor from the sensing system. Instead of using four sensors where one provides timing signals, the invention uses only three bi-stable sensors that inherently provide both position and timing information through their state transitions, eliminating the source of false clocking signals caused by system noise

Inventive Principle:

Principle #2Taking out (Extraction)

Solution Approach 2:

The bi-stable sensors provide inherent feedback through their stable state transitions. Each sensor maintains one of two states and transitions only when triggered by a sense element, creating reliable position information without requiring external clock signals that could be corrupted by noise

Inventive Principle:

Principle #23Feedback

2Loss of information

If binary code is used for position identification, then position information is provided, but the number of sense elements required is sub-optimal

Engineering Contradiction:

Improveposition identification accuracyVSAvoidnumber of sense elements

Core Design Contradiction:

Loss of informationVSQuantity of substance

Solution Approach 1:

The patent changes the coding parameter from binary code to gray code. This parameter change allows for more efficient position identification where each zone transition requires only one sensor state change, reducing the number of sense elements needed while maintaining accurate position information

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The hoistway is segmented into multiple zones with each zone represented by a unique gray code combination of the three bi-stable sensors. This segmentation approach allows comprehensive position coverage with minimal sensors by utilizing the combinatorial states of the segmented zones

Inventive Principle:

Principle #1Segmentation

Data Source

PatentUS9296591B2Determining elevator car position using bi-stable sensors

Publication Date: 2016.03.29 OTIS ELEVATOR CO

AI summary

A system for monitoring elevator car travel includes a plurality of bi-stable sensors (12) traveling with an elevator car (10); a plurality of sense elements (20) positioned along a path of the sensors (12); the sense elements (20) causing the sensors (12) to assume one of a first state and a second state; wherein states of the sensors (12) define a zone code (30) identifying a zone corresponding to the elevator car (10) position, the zone code (30) being a gray code.