Absolute Encoder Position Detection for Vehicle Doors

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Solution Overview

Problem

Existing entry/exit devices for vehicles, such as doors and ramps, face challenges with wear-resistant and reliable position detection systems, particularly due to the limitations of potentiometer designs and inaccessible switching contacts, leading to complex and time-consuming adjustments and increased downtimes.

Innovation Solution

The implementation of an absolute encoder system that compares instantaneous positions with stored reference values using a non-volatile memory, eliminating the need for limit switches and enabling simplified position detection and adjustment, with the absolute encoder being contactless and providing precise position feedback.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If switching contacts are used for position detection, then reliability can be improved, but adjustment becomes time-consuming due to poor accessibility

Engineering Contradiction:
Improveposition detection reliabilityVSAvoidadjustment time
Core Design Contradiction:
ReliabilityVSLoss of time

Solution Approach 1:

The patent replaces mechanical switching contacts with an absolute encoder that detects position non-contactually. This substitution eliminates the need for mechanical adjustment of switching contacts while maintaining reliable position detection, directly resolving the contradiction between reliability and adjustment time.

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

2Measurement precision

If switching contacts are arranged on moving elements, then position detection accuracy is improved, but accessibility for adjustment deteriorates

Engineering Contradiction:
Improveposition detection accuracyVSAvoidaccessibility for adjustment
Core Design Contradiction:
Measurement precisionVSEase of operation

Solution Approach 1:

The absolute encoder mounted on the drive mechanism provides non-contactual position detection with high precision, eliminating the need to access switching contacts on moving elements. This resolves the contradiction by maintaining measurement precision while dramatically improving accessibility for adjustment.

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

3Volume of moving object

If compact drive design is implemented, then space efficiency is improved, but accessibility of switching contacts deteriorates

Engineering Contradiction:
Improvedrive system compactnessVSAvoidswitching contact accessibility
Core Design Contradiction:
Volume of moving objectVSEase of operation

Solution Approach 1:

By replacing switching contacts with an absolute encoder on the drive mechanism, the system achieves compact design without compromising accessibility. The encoder requires no adjustment access, allowing compact integration while maintaining ease of operation for position detection.

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

4Reliability

If mechanical components are used for position detection, then reliability can be improved, but wear and play increase over time requiring readjustment

Engineering Contradiction:
Improveposition detection reliabilityVSAvoidservice life without readjustment
Core Design Contradiction:
ReliabilityVSDuration of action of stationary object

Solution Approach 1:

The absolute encoder provides non-contactual position detection that eliminates mechanical wear and play accumulation. This substitution maintains high reliability throughout the service life without requiring periodic readjustment, directly resolving the contradiction between initial reliability and long-term durability.

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

Data Source

PatentEP2212504B1Drive system for pivotal and/or slidable doors or for entry and exit facilities with improved position acquisition
Publication Date: 2015.03.04 GEBR BODE GMBH & CO KG
  • EP2212504B1 patent drawingFigure 1
  • EP2212504B1 patent drawingFigure 2

AI summary

The invention relates to a drive system for an entry/exit facility with at least one pivotally and/or slidably supported door, ramp, step or the like of a vehicle for passenger transport. It comprises at least one actuator or drive motor (1, 24) and a mechanism (3.3, 3.4) driven thereby and/or a gearbox (2, 4, 26) in order to effect the pivoting or sliding motion of the door, ramp, step or the like, having an absolute encloder (7, 34) for acquiring a current position during the pivoting or sliding motion. An evaluation unit is designed to compare the current position to at least one reference position, which is stored in a non-volatile memory of the evaluation unit so as to generate an output signal dependent thereon. The absolute encoder (7, 34) is flange-mounted to a trunnion fixing the pivoting motion of the door, ramp, step or the like, and the gearbox comprises a first reduction gear (2) and a second reduction gear(4), and an actuatable coupling (3.3, 3.4) is provided between the reduction gears (2, 4).