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Aircraft Deck Motion Compensation Design




ACQUISITION PROGRAM: PMA-268, Navy Unmanned Combat Air System Demonstration

OBJECTIVE: Develop deck motion compensation algorithm and control law design methodology and guidance via airborne and/or shipboard sensors (e.g. GPS and rate/acceleration gyros) to improve aircraft boarding rate capabilities in high ship motion conditions.

DESCRIPTION: The Navy continues to invest in the development of shipboard automated landing systems and Unmanned Air System (UAS) capabilities. One important area of investment is improved boarding rates in high sea state conditions with large ship motions. Due to legacy systems’ computational and hardware restrictions, current systems only account for the basic movement of the touchdown point with altitude rate and bank angle commands. The systems become unreliable and unusable as the sea state increases which then greatly increases pilot workload and decreases recovery rate. Autonomous and highly augmented aircraft can integrate more sensor information and increase boarding rates using advanced data fusion and control algorithmic techniques. The Navy’s Unmanned Combat Air System demonstration (UCAS-D) program successfully completed several carrier demonstration events using a more advanced deck motion compensation (DMC) scheme, but only in benign sea states.

Control law methods for ship motion and aircraft data fusion and flight control are needed to enable Naval Aviation operations at the worst sea state conditions. These types of algorithms exist and have been used in the past in limited scenarios (i.e. X-47B) and disparate scenarios (e.g. relative position flight control of UAS in swarms). Unfortunately, the implementations have relied on extensive analysis techniques (e.g. Monte Carlo variations of environmental conditions and sub-system capabilities) to test the robustness and precision of the control systems, or were flight tested without airworthiness certifications. Early design and performance guidance (including sensitivities to sensor accuracy, precision, data rate, latency, and reliability), for deck motion measurements, prediction methods, sensor noise and errors, and DMC control algorithms need to be created to support future aircraft development and improvements.

A design guidance and conceptual analysis toolset is needed for existing simulation environments to demonstrate the six-degree-of-freedom (6DOF) simulation response of an aircraft during a shipboard recovery. The environments need to be able to incorporate variations in ship deck (landing/recovery location) motion, environmental disturbances (e.g. turbulence, ship airwake, etc.), and sensor errors/noise to assess the feasibility of the developed design guidance using DMC algorithms and control law design methodology and analysis tools.

PHASE I: Develop preliminary detailed aircraft design guidance for DMC control schemes addressing deck motion measurements, prediction methods, sensor noise and errors, data fusion, aircraft performance, and flight characteristics and control. Develop a conceptual analysis toolset for ship-based recovery and show feasibility of the design guidance with a prototype DMC control method and publically available shipboard environment inputs. The preliminary design guidance and conceptual analysis toolset will be evaluated against algorithm coverage scope, system level accuracy (e.g. approach flight path maintenance and touchdown point location), robustness to control law methods and variations in input data, and incorporation of sea-based aviation environmental considerations.

PHASE II: Mature the DMC design guidance and analysis toolset using multiple prototype DMC schemes, including data source fusion and control algorithms. Perform sensitivity analyses on the DMC schemes to determine what information, and the associated sensor accuracy, precision, data rate, latency, and reliability, needs to be fed back to the system. Identify the data and information types that are required for successful DMC schemes, those that provide improvements to boarding rate and reliability, and the ones that do not impact a DMC scheme performance. Identify flight control law techniques (e.g. vehicle control of flight path, attitudes, rates, accelerations, etc.) and develop associated design and performance guidance for DMC concepts. Show feasibility of the design guidance by evaluating how aircraft performance capabilities and flight limitations affect the DMC schemes performance and reliability. Document the design guidance with technical rationale including the results of the sensitivity studies and the impact of the individual criteria on the overall system’s recovery capabilities.

PHASE III DUAL USE APPLICATIONS: Finalize and transition the DMC design guidance and analysis toolset by validating them with additional aircraft and simulation sources, as required. Integrate the results into future Navy programs, such as UCLASS, Fire Scout, RQ-21A, F-18, and Joint Strike Fighter, to enable the development of advanced shipboard landing control laws with DMC. Private Sector Commercial Potential: The deck motion compensation concept design guidance and toolset developed under this SBIR are relevant in applications beyond Navy shipboard approach and landing. The underlying technologies can be used with commercial off the shelf UAS platforms that operate on personal, research, or corporate ships to provide improved recovery performance and operational usefulness. Other applications include other two-body relative navigation like formation flight, swarm operations, and vehicle tracking.


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KEYWORDS: Airworthiness; Unmanned Air Vehicle; Shipboard Landing; Ship Motion; Control Law Design; Sea-Based Aviation

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