Helicopter Shipboard Landing Relative Navigation System
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Solution Overview
Problem
Helicopter shipboard landing operations face challenges due to unpredictable wind and wake turbulence, which affect the consistency and safety of takeoff and landing, especially in rough sea conditions, requiring pilots to manually adjust for heave, pitch, and roll motions of the landing platform.
Innovation Solution
A relative navigation system using a pair of Inertial Navigation Units (INU) and Differential Global Positioning Systems (IDGPS) with a modified RTK algorithm, enabling accurate and low-latency position and attitude data exchange between a ship-based and helicopter-based unit, reducing relative position error to less than 50 cm, allowing for precise and consistent landing operations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If manual pilot judgment and reaction time are used to determine landing contact time, then the system is simple and requires no complex equipment, but the landing precision and consistency deteriorate due to human reaction time limitations and unpredictable sea conditions
Solution Approach 1:
The patent introduces an intermediary system consisting of inertial navigation units (INS) on both the helicopter and ship, combined with a range gate and processing equipment. This intermediary automatically measures and processes the distance and relative motion between helicopter and ship, eliminating the need for pilot judgment and providing precise landing guidance, thereby resolving the contradiction between landing precision and system complexity
Solution Approach 2:
The patent replaces the mechanical human pilot judgment and reaction time system with an automated electronic measurement and control system. The inertial navigation units, range gate, and processing equipment form an automated system that continuously measures distance and relative motion, substituting human cognitive and motor functions with mechanical and electronic systems to achieve consistent precise landing
2Reliability
If the helicopter maintains a safe distance above the landing deck during heaving sea conditions, then safety is improved, but the accuracy of altitude control deteriorates due to deck motion variation
Solution Approach 1:
The patent implements a feedback mechanism where the inertial navigation units continuously measure the relative position and motion between helicopter and ship, and this information is fed back to guide the helicopter's approach and landing. The system provides real-time feedback on distance and relative motion, enabling the pilot to maintain safe distance while achieving accurate altitude control despite deck heave motion
Solution Approach 2:
The patent uses preliminary action by having the inertial navigation units and range gate continuously measure and process distance information before the actual landing contact. The system prepares and provides guidance information in advance, allowing the pilot to anticipate and compensate for deck motion, thereby maintaining both safety distance and altitude control accuracy
Data Source
AI summary
A system for maneuvering an aircraft for operations in connection with a sea-going vessel, the vessel having a designated area for landings and sling-load operations. Each of the aircraft has a navigation unit (INU) comprising a GPS receiver and an inertial navigation unit. The INU's are updated by data from the GPS receivers and the data from the shipboard unit's GPS receiver and INU are transmitted to the aircraft. The aircraft performs RTK calculations to determine a vector to the shipboard GPS antennas and modifies the vector with data from the INU's.