Showing papers by "Robert F. Stengel published in 1981"
26 Oct 1981
TL;DR: This instrumentation package will use a quaternion-based ¿strapdown IMU¿ algorithm to derive vehicle attitude from angular rate data, and it will use fault-detection logic to identify inflight sensor failures.
Abstract: Accurate data are necessary for the identification of aerodynamic parameters at high angle of attack and in spinning flight. Modern sensors and microelectronic devices are employed in a stall/spin data acquisition system that will be tested in a Schweizer 2-32 sailplane. This instrumentation package will use a quaternion-based ?strapdown IMU? algorithm to derive vehicle attitude from angular rate data, and it will use fault-detection logic to identify inflight sensor failures. Details of the system and flight test program are presented, together with results of preflight digital simulation analysis.
4 citations
19 Aug 1981
TL;DR: In this paper, the authors interpret existing flying qualities criteria in a multivariable format based upon state vectors and matrices of stability and control derivatives, which are shown to be entirely compatible with conventional flying qualities analysis.
Abstract: The objective of this paper is to interpret existing flying qualities criteria in a multivariable format based upon state vectors and matrices of stability and control derivatives. State-space methods are shown to be entirely compatible with conventional flying qualities analysis. Furthermore, they lead to a definition of the well-known control anticipation parameter that has potential utility in the evaluation of higher-order aircraft/control systems.
1 citations
01 Jan 1981
TL;DR: In this paper, the stability limits imposed by control saturation are presented using state trajectories with control limiting, as well as describing functions and eigenvalue computation, and an investigation of the interaction of the state-space saturation and stability boundaries for various choices of LQ weighting matrices.
Abstract: Methodologies are presented for the analysis and design of stability augmentation control laws for aircraft in which 'hard' displacement and rate limiting are significant. Candidate control laws are derived using the linear-quadratic (LQ) regulator. Analytical and computational estimates of the stability limits imposed by control saturation are presented using state trajectories with control limiting, as well as describing functions and eigenvalue computation. Analysis also includes an investigation of the interaction of the state-space saturation and stability boundaries for various choices of LQ weighting matrices. For minimum-energy control, the saturation and stability boundaries are shown to be parallel. In this case, there is a direct relation between the solution to the matrix Riccati equation and the aircraft's open-loop dynamics.