Dead Reckoning Heading Adjustment Using Lock Angle Multiples

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Solution Overview

Problem

Navigation devices face challenges in areas with low GPS signal reception, such as covered or underground parking structures, where inaccuracies in accelerometer and gyroscope data can lead to significant errors in determining the device's location, causing navigation issues upon exiting these areas.

Innovation Solution

The implementation of a dead reckoning navigation system that uses reference distances and angles to accurately determine the navigation device's heading and location, even in the absence of wireless navigation signals, by employing a method that sets a reference heading based on long and short distances traveled and adjusts headings to integer multiples of a lock angle, reducing errors associated with sensor mis-calibration.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If dead reckoning navigation is used in low GPS signal areas, then navigation functionality is maintained, but location accuracy deteriorates due to sensor inaccuracies

Engineering Contradiction:
Improvenavigation functionalityVSAvoidlocation accuracy
Core Design Contradiction:
ReliabilityVSMeasurement precision

Solution Approach 1:

The patent applies parameter changes by adjusting the dead reckoning calculation parameters dynamically. When GPS signal quality is poor or unavailable, the system switches to using accelerometer and gyroscope data with adjusted integration parameters. The system modifies the calculation time window and filtering parameters to optimize accuracy under degraded signal conditions, thereby maintaining navigation functionality while managing the inherent accuracy loss of dead reckoning.

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

The patent implements feedback mechanisms by continuously monitoring GPS signal quality and using it to adjust the navigation system's operation. When GPS signals are available, the system uses them directly and feeds back the position information to correct accumulated dead reckoning errors. When GPS signals are poor, the system switches to dead reckoning mode and uses the last known accurate position as a reference, creating a feedback loop that maintains reliability while managing accuracy degradation.

Inventive Principle:
Principle #23Feedback

2Adaptability or versatility

If accelerometer and gyroscope data are used for dead reckoning, then navigation is possible in low signal areas, but errors accumulate leading to significant location inaccuracies

Engineering Contradiction:
Improvenavigation in low signal areasVSAvoidlocation accuracy
Core Design Contradiction:
Adaptability or versatilityVSMeasurement precision

Solution Approach 1:

The patent applies preliminary action by establishing a reference position and heading before entering low signal areas. The system uses the last known accurate GPS position and heading as a baseline for dead reckoning calculations. By preparing this reference information in advance while GPS signals are still reliable, the system can maintain better accuracy during the transition to dead reckoning mode, reducing the accumulation of errors that would otherwise occur.

Inventive Principle:
Principle #10Preliminary action

Solution Approach 2:

The patent implements dynamics by making the navigation system adaptive and dynamic in its operation. The system continuously adjusts between GPS-based navigation and dead reckoning based on real-time signal quality assessment. When entering low signal areas, the system dynamically switches calculation methods and adjusts the weighting of sensor data to optimize performance under changing conditions, thereby maintaining adaptability while managing error accumulation.

Inventive Principle:
Principle #15Dynamics

3Duration of action of moving object

If sensor data is processed continuously to maintain location tracking, then navigation continuity is improved, but computational complexity and energy consumption increase

Engineering Contradiction:
Improvenavigation continuityVSAvoidenergy consumption
Core Design Contradiction:
Duration of action of moving objectVSUse of energy by moving object

Solution Approach 1:

The patent applies periodic action by implementing discontinuous measurement and batch processing of sensor data. Instead of continuously processing accelerometer and gyroscope data at high frequency, the system processes sensor information at lower, periodic intervals. This approach maintains navigation continuity by updating position estimates periodically while significantly reducing the computational load and energy consumption associated with continuous high-frequency processing.

Inventive Principle:
Principle #19Periodic action

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

This approach enhances navigation accuracy in low signal areas by minimizing errors in dead reckoning, allowing the device to accurately determine its location and provide reliable navigation upon exiting areas with poor signal reception.

Implementation Method 1

PND devices of this type also include a GPS antenna by means of which satellite-broadcast signals, including location data, can be received and subsequently processed to determine a current location of the device

Methodology Applied
Scientific EffectGPS signal reception:

Implementation Method 2

The PND device may also include electronic gyroscopes and accelerometers which produce signals that can be processed to determine the current angular and linear acceleration

Methodology Applied
Scientific EffectGyroscope: Gyroscope

Implementation Method 3

The PND device may also include electronic gyroscopes and accelerometers which produce signals that can be processed to determine the current angular and linear acceleration

Methodology Applied
Scientific EffectAccelerometer: Accelerometer

Data Source

PatentEP2729765B1Navigation device having dead reckoning navigation functionality and method thereof
Publication Date: 2017.05.31 TOMTOM INT BV
  • EP2729765B1 patent drawingFigure 1~2
  • EP2729765B1 patent drawingFigure 3
  • EP2729765B1 patent drawingFigure 4~5

AI summary

Embodiments of the present invention provide a method of determining a heading of travel of navigation device (200), comprising determining a reference heading for a roadway system and determining a current heading of navigation device (200) travel, wherein the current heading is determined as an integer multiple of a predetermined lock angle in combination with the reference heading.