Hybrid RFID Inductive Positioning System for Absolute Tracking
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Solution Overview
Problem
Existing position determination systems are either unreliable or expensive, particularly when determining the exact position of large-scale objects like cranes in port areas or rotary encoders with diameters over several meters, as they often require incremental systems and stored values for accurate positioning.
Innovation Solution
A position determination system combining an RFID transponder reading unit and an induction detector unit with a metallic sub-transmitter unit, allowing for immediate absolute position determination without moving the reading head, using passive RFID transponders and metallic materials to enhance accuracy and reliability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If incremental position determination systems are used, then the system can track position changes, but the position cannot be determined immediately after power-up without incremental movement
Solution Approach 1:
The patent combines RFID transponder technology with inductive position sensing to create a hybrid system. The RFID transponder provides absolute position information immediately upon power-up, while the inductive sensor provides continuous incremental position tracking. This merging of two different positioning technologies resolves the contradiction by eliminating the warm-up time requirement while maintaining continuous position determination capability.
Solution Approach 2:
The RFID transponder acts as an intermediary that provides absolute position reference points. Instead of relying solely on incremental movement from a reference position, the system uses RFID transponders placed at known locations along the travel path to immediately establish absolute position coordinates when detected, thereby eliminating the time delay associated with incremental systems.
2Ease of manufacture
If RFID transponders alone are used for position determination, then the system is simple and inexpensive, but the accuracy decreases at distances over 10 m
Solution Approach 1:
The patent merges RFID transponder reading with inductive position sensing in a combined sensor unit. The RFID component provides cost-effective, simple positioning at close range, while the inductive sensor component compensates for RFID signal degradation at distances over 10 meters. This combination maintains manufacturing simplicity while extending accurate measurement capability to longer distances.
Solution Approach 2:
The system uses different sensing technologies optimized for different distance ranges. The RFID transponder is optimized for short-range, low-cost positioning, while the inductive sensor is activated or weighted more heavily at longer distances where RFID accuracy degrades. This local quality approach ensures optimal accuracy for each distance range while maintaining overall system simplicity.
3Reliability
If inductive position sensors alone are used, then the system provides continuous position tracking, but the system becomes expensive to manufacture and use
Solution Approach 1:
The patent creates a hybrid sensor unit that merges RFID reading capability with inductive position sensing. The inductive sensor provides continuous position tracking capability, while the RFID transponder adds absolute position reference. By sharing the sensor unit hardware and processing infrastructure between the two technologies, the system achieves continuous tracking reliability without proportionally increasing manufacturing costs.
Solution Approach 2:
The sensor unit is designed with multi-functionality, serving both RFID transponder reading and inductive position sensing functions within a single integrated device. This universality allows the system to achieve continuous position tracking through the inductive sensor while using the same hardware platform for RFID operations, thereby avoiding the need for completely separate expensive inductive positioning systems.
4Measurement precision
If optical incremental position encoders are used, then the system provides precise position measurement, but the system becomes sensitive to dirt and environmental factors
Solution Approach 1:
The patent replaces optical sensing mechanisms with inductive sensing. Instead of using light-based optical encoders that are sensitive to dirt and environmental interference, the system uses electromagnetic induction-based position sensing. This substitution eliminates the optical path that would be blocked or scattered by dirt, providing the same precise position measurement capability while being robust against environmental contaminants.
Solution Approach 2:
The system changes the physical parameter used for position sensing from optical (light) to electromagnetic induction (magnetic field). This parameter change fundamentally alters how position is detected, replacing light-based measurement with magnetic field-based measurement. The magnetic field approach maintains measurement precision while being inherently more resistant to dirt and environmental factors that interfere with optical systems.
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 system provides precise and reliable absolute position determination, capable of functioning immediately after power-up without incremental movement, with increased accuracy at distances over 10 m, and is robust against dirt and power failures, suitable for safety-critical applications.
Implementation Method 1
the sensor unit comprises a first RFID transponder reading unit and a first induction detector unit
Implementation Method 2
the induction detector unit is set up for determining the absolute position and outputs a second position value
Implementation Method 3
Another position determination system is known from WO 2008/101702. In order to determine the position of a turning wheel, the induction is detected in a sensor of the magnets arranged on the turning wheel.
Data Source
AI summary
The invention relates to a positioning system, comprising a sensor unit and a transmitter unit, wherein the sensor unit comprises a first RFID transponder reading unit and a first induction detector unit and an evaluating unit connected to the RFID transponder reading unit and to the induction detector unit, the transmitter unit comprises an RFID transponder and a metal material, the sensor unit can be moved relative to the transmitter unit, the RFID transponder reading unit is designed for absolute positioning and outputs a first position value, the induction detector unit is designed for absolute positioning and outputs a second position value, and the evaluating unit is designed to determine an absolute position of the sensor unit from the first position value and the second position value from the data determined by the transmitter unit.