Mobile Machine Positioning with Sensor Reliability Switching
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Solution Overview
Problem
Existing position identification systems for mobile machines, such as those in hazardous or GNSS-degraded environments, face inaccuracies and disruptions due to satellite signal interference, and inertial navigation systems suffer from error accumulation over time, leading to unreliable positioning.
Innovation Solution
A system integrating motion sensors, GPS receivers, and an integration module with a controller that determines reliability and switches to dead reckoning when information becomes unreliable, using a Kalman filter for noise reduction and cross-checking with multiple sensors and external position data to ensure accurate positioning.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If GPS is used for positioning, then absolute position information can be obtained, but positioning becomes unreliable in GNSS-degraded environments
Solution Approach 1:
The patent combines GPS receiver with inertial sensors (accelerometers and gyroscopes) to create an integrated positioning system. The GPS provides absolute position references while inertial sensors provide continuous relative motion data, allowing the system to maintain positioning reliability when GPS signals are degraded or blocked by using the inertial data to bridge GPS signal gaps.
Solution Approach 2:
The inertial sensors act as an intermediary between GPS measurements, providing continuous position estimates during GPS signal interruptions. The system uses inertial data to maintain positioning continuity and then corrects drift when GPS signals become available again, ensuring reliable positioning throughout.
2Reliability
If inertial navigation system is used for positioning, then positioning can continue without external signals, but error accumulates over time
Solution Approach 1:
The system uses GPS measurements as feedback to correct inertial navigation drift. When GPS signals are available, the system compares the inertial position estimate with the GPS position and applies corrections to eliminate accumulated errors, maintaining long-term positioning accuracy.
Solution Approach 2:
The system performs preliminary integration of inertial sensor data to generate continuous position estimates, then uses GPS measurements to correct errors before they accumulate significantly. This preliminary action allows the system to maintain positioning during GPS outages while preparing for error correction when signals return.
3Reliability
If multiple sensors are integrated for positioning, then positioning reliability improves, but system complexity increases
Solution Approach 1:
The controller performs multiple functions: it processes GPS data, integrates inertial sensor data, determines sensor reliability, and switches between positioning sources. This multi-functionality consolidates what could be separate complex systems into a single integrated unit, managing complexity while maintaining high positioning reliability.
Data Source
AI summary
A position identification system for use with a mobile machine at a worksite is disclosed. The system may include an integration module configured to integrate information from at least one motion sensor and at least one GPS receiver to generate a location signal indicative of an actual location of the mobile machine. A controller may be provided in communication with the at least one motion sensor, the at least one GPS receiver, and the integration module, the controller being configured to determine the reliability of information received from the at least one motion sensor, the at least one GPS receiver, and the integration module, and following a period of time from when received information is first determined to be unreliable, switching from determining the position of the mobile machine using information determined to be unreliable to determining the position of the mobile machine using dead reckoning from a last known good position of the mobile machine, a determined wheel speed of the mobile machine, and a steering command being provided to the mobile machine.