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Flight Control Optimization
 

The Control Designer's Unified Interface (CONDUIT), developed at Ames Research Center , has changed the traditional flight control design process by unifying all of the necessary elements needed in flight control design.

Benefit
CONDUIT is a state-of-the-art design tool that has been used on both manned and unmanned aerial vehicles. CONDUIT can provide critical design help in a time-efficient and cost-effective manner to any vehicle that has a control system. This suite of tools has revolutionized the aviation industry, enabling a rapid, low-cost design of control systems for a wide spectrum of aerial vehicles, including planetary exploration vehicles. CONDUIT accounts for safety from the start allowing the designer to specify, and design to, safety specifications.

Research Overview
CONDUIT The dynamics and control of new vehicles remains a significant technical challenge. CONDUIT was used to abate these challenges in a cost-effective manner to achieve credible flight control designs on industry programs such as Boeing’s Joint Strike Fighter, Northrop-Grumman’s Vertical Takeoff Unmanned Aerial Vehicle (UAV), Kaman’s BURRO (UAV), and Microcraft’s 9-inch diameter Lift Augmented Ducted Fan (UAV). Each of these programs used CONDUIT and flew the first time successfully. The success of this advanced engineering tool in enabling a "rapid, high-confidence, and cost efficient design of revolutionary systems" is validated by the simple fact that the above industry partners paid Ames to use the tool, and in each case, the tool delivered.

Right: Screenshot of the CONDUIT Interface.

Previously, industry used home-grown tools that solved segregated pieces of the flight control problem. This added cost and complexity. CONDUIT brought all the pieces under one umbrella while also integrating another industry standard analysis package, Matlab, into the mix in an innovative fashion. Thus, engineers can use their existing software and data and fold it into CONDUIT seamlessly.

CONDUIT’s level of accomplishment and technical performance are unsurpassed for flight control. Specifically, this tool creates a flight control system that simultaneously satisfies tens or hundreds of performance and safety specifications. Previously, engineers were unsure if this was even possible, let alone to be able to find a solution. What enables these solutions is a clever, state-of-the-art, minimax vector optimization scheme. This optimization engine allows a flight control designer to rationally tradeoff a set of competing constraints and objectives, which is the hallmark of any flight control design.

CONDUIT reduces the analysis time for the first flight condition to one hour and each subsequent condition to five minutes. This allows overnight turnaround for a new control design. To date, this is unheard of in the flight control discipline, and it has changed its culture. Since CONDUIT completely evaluates and optimizes the resulting control design against performance specifications, record cycle time reductions are achieved simultaneously with improved system performance. Improved system performance, in a handling qualities context, improves flight safety.

CONDUIT represents a significant new capability in flight control design, development, and integration. The system is built on top of the highly flexible MATLAB/SIMULINK system modeling and analysis environment, which includes a graphical block diagram editor and block-diagram-to-code features.

Key Features of CONDUIT include: Flying vehicle that have used CONDUIT

  • Graphical User Interface
  • Built-in Libraries
  • Customizable Specifications
  • Easy Problem Set-up
  • Quick Access to Detailed Information
  • Optimization and Organized Results
  • External Scripts Plug-in
  • Sensitivity and Robustness Studies
  • Integration with CIFER Database
  • Batch Mode Evaluation
Right: Flying vehicles that have used CONDUIT.

Tools are provided for the user to gain insight about relationships between specifications and design parameters during the optimization process, and they allow the user to analyze the control system to determine if it can maintain its robustness with the presence of uncertainties within the system.

Background
Developing flight control systems for today's aerospace vehicles is time consuming. While the theory is understood, its application is lengthened as a result of three factors. First, flight control is an interdisciplinary subject that integrates math models, control theory, computers, hydraulic and electrical systems, specifications, and pilots. Combining these pieces into a unified framework is a challenge. Second, imperfect knowledge of a contributing component results in costly flight-test iterations. Manufacturers have previously allotted 25% of the total flight test development time for flight control evaluation and iteration. Third, after a control system design is finalized, it can take two weeks to just evaluate the control system against the myriad of often conflicting design specifications. CONDUIT ruthlessly attacks these three complicating factors with a vengeance, and as a result, embodies the description of "Pioneering Technology Innovation Enabling a Revolution in Aerospace Systems" and "Engineering Innovation."