Modernized Control Laws for UH-60 BLACK HAWK Optimization and Flight-Test Results

Abstract

Modernized control laws were developed to provide an attitude-command/attitude-hold response type for the UH-60 BLACK HAWK helicopter and thereby afford improved handling qualities for near-Earth operation in night and poor weather. The inner-loop system modernized control laws were implemented using the 10% authority stability augmentation system actuators and was evaluated in an EH-60L helicopter. Central to addressing the significant resource and technical challenges of this project was the extensive use of a modern integrated tool set. System identification methods provided an accurate flight-identified aircraft response model and allowed the efficient isolation of discrepancies in the block diagram-based simulation model. Additional key tools were real-time rapid prototyping and a well-designed picture-to-code process. Control laws were tuned to achieve the maximum design margin relative to handling qualities and control system performance requirements. The optimized design was seen to be robust to uncertainties in the identified physical parameters. A flight-test evaluation by three test pilots showed significant benefits of the optimized design compared to the BLACK HAWK standard flight control configuration.

Modified Guidance Law and Operational Logic for Auto-Approach of Unmanned Air Systems

“…8) This paper applied the multi-objective parameter optimization method using Control Designer's Unified Interface (CONDUIT) tool, which has been proven through successful applications for UH-60 and Fire Scout MQ-8 in previous studies. 9,10) All simulation codes are made under the Matlab/Simulink environment and integrated with the logics presented in the previous sections using the Stateflow program in order to facilitate the real-time implementation and generation of the C-codes for loading in the onboard flight control computer (FCC).…”

Aircraft and Rotorcraft System Identification

“…Tischler et al 20 documented the development of modernized control laws (MCLAWS) to provide an attitude-command/attitude-hold response type for the UH-60 and thereby afford improved handling qualities for near-Earth operation in night and poor weather. Initial flight tests of the baseline gain set showed significant qualitative discrepancies with the predicted characteristics based on the SIMULINK ® analysis model.…”

“…This ensured that the improvements seen in analysis and simulation would be realized in flight. A full discussion of control law validation and final handling-qualities performance is presented in Tischler et al 20 Numerical linearization of complex block diagram models (e.g., using the MATLAB ® function linmod) for the purpose of obtaining a state-space representation can be problematic and should be checked before using the result in linear analyses. Time integration of the block diagram model can be considered to be accurate.…”

“…Rupnik also developed a prototype MATLAB ® GUI that provides the user with a more modern browser-type interface, while preserving the same CIFER ® screen organization and flow. Tischler et al 20 have integrated CIFER ® and the control system design tool CONDUIT ® . The CONDUIT ® tool can access directly the identified models and accuracy bounds from the CIFER ® database to allow control-system optimization and robustness analysis, as described in the cited reference.…”

“…The accurate determination of flight-control parameters and the rapid solution of complex flight-control interactions on modern aircraft demand a degree of model precision that can quickly (and perhaps only) be achieved using system identification (e.g., Refs. [17][18][19][20] in the early flight-test stage. Systemidentification results can then be used to update the physics-based simulation models (as in Tischler et al 17 ).…”