Aircraft and Rotorcraft System Identification

Contents......Page 7
List ofFigures......Page 13
List ofTables......Page 21
Nomenclature......Page 25
Acronyms......Page 31
Preface......Page 33
1.1 Basic Concepts of System ldentification......Page 39
1.2 Relationship Between Simulation......Page 44
1.3 Special Challenges of Rotorcraft System......Page 46
1.4 More About the Role of Nonparametric......Page 47
1.5 Frequency-Response Identification Method......Page 50
1.6 Role and Limitations of Flight-Mechanics......Page 55
1.7 Brief History of the Developmen......Page 56
1.8 Organization of this Book......Page 58
Problems......Page 60
2.1 Road Map of Frequency-Response......Page 63
2.2 Key Features of the Frequency-Response......Page 67
2.3 Frequency-Response Identification Method......Page 73
2.4 Examples of CIFER@ Applications......Page 89
Problems......Page 91
3.1 Pendulum Example Problem......Page 93
3.3 XV-15 Dynamic Characteristics in Hover......Page 96
3.4 Measurements for Closed-Loop Hover Flight......Page 98
3.5 XV-15 Test Case Database for Hover......Page 100
3.7 Measurements for Open-Loop Cruise Flight Testing......Page 102
3.8 XV-15 Test Case Database for Cruise......Page 103
Problems......Page 105
4.1 Basic Characteristics of the CIFERm Software......Page 107
4.2 Dataflow Through CIFERB......Page 109
4.4 CIFERm User Interface......Page 111
4.5 Examples of CIFER~U tilities......Page 116
4.6 Interfaces with Other Tools......Page 117
Problems......Page 119
5.1 Overview of Data Requirements......Page 121
5.2 Optimal Input Design......Page 123
5.3 Recommended Pilot Inputs......Page 124
5.4 Instrumentation Requirements......Page 126
5.5 Overview of Piloted Frequency Sweeps......Page 128
5.6 Detailed Design of Frequency-Sweep Inputs......Page 130
5.7 Flight-Testing Considerations......Page 132
5.8 Open-Loop vs Closed-Loop Testing......Page 133
5.9 Piloted Frequency SweepS......Page 135
5.10 Summary of Key Points in Piloted Frequency-......Page 138
5.1 1 Computer-Generated Sweeps......Page 140
5.12 Frequency-Response......Page 150
Problems......Page 155
6.1 Modeling Measurement Errors......Page 157
6.2 Simple Methods for Data Consistency......Page 167
Problems......Page 181
7-Single-Input 1 Single-Output......Page 183
7.1 Definition of Frequency Response......Page 184
7.2 Relating the Fourier Transform......Page 185
7.3 Simple Example of Frequency-......Page 187
7.5 Calculating the Fourier Transform......Page 190
7.6 Interpreting Spectral Functions......Page 196
7.7 Frequency-Response Calculation......Page 197
7.8 Coherence Function......Page 203
7.9 Random Error in the Frequency-Response Estimate......Page 205
7.10 Window Size Selection and Tradeoffs......Page 207
7.1 1 Frequency-Response Identification......Page 213
7.13 Pendulum Example......Page 215
7.1 4 Applications and Examples......Page 216
Problems......Page 241
8.1 Limiting Conditions in Closed-Loop......Page 247
8.2 Quantification of Bias Errors......Page 249
8.3 Bias Errors Defined......Page 251
8.4 Numerical Study of Identification......Page 253
8.5 Flight-Test lrnplications......Page 262
8.6 ldentification of Unstable Inverted......Page 263
Problems......Page 264
9.1 Multi-Input Terminology......Page 267
9.2 Need for Multiple-Input Identification......Page 268
9.3 Simple Two-Input Example......Page 269
9.4 Conditioned Spectral Quantities......Page 275
9.5 Example of aTwo-Input Identification Solution......Page 277
9.6 General MIMO Solution......Page 283
9.7 High Control Correlation......Page 286
9.8 Multiple-Input Identification in CIFER@......Page 287
9.9 Example of MIS0 Solution for a Hovering......Page 288
9.10 MIMO Identification Using a Multi-......Page 292
9.1 1 Determination of Broken-Loop Response......Page 294
Problems......Page 295
10.1 Background......Page 297
10.2 Composite-Window Approach......Page 298
10.5 Composite-Window Results......Page 301
10.6 COMPOSITE Windowing in Single-......Page 304
10.7 Composite-Windowing Results......Page 306
10.8 Composite-Windowing Results......Page 309
10.9 Composite Results for Structural......Page 311
10.10 Composite Windowing in Spectr......Page 312
Problems......Page 313
11 .I Motivations for Transfer-Function Modeling......Page 315
11.2 Transfer-Function Modeling......Page 316
11.3 Model Structure Selection......Page 319
11.4 SlSO Transfer-Function Identificatio......Page 322
11.5 Pendulum Example......Page 323
11.6 Handling-Qualities Applications......Page 324
11.7 Flight-Mechanics Characterization Studies......Page 336
11.8 Flight-Dynamics Models for Control......Page 345
11.9 Aeroelastic Model Identification......Page 348
11.10 Subsystem Component Modelin......Page 352
Problems......Page 355
12-State-Space Model Identification......Page 359
12.1 Background......Page 360
12.2 MIMO State-Space Model Identification......Page 361
12.3 Accuracy Analysis......Page 368
12.4 Key Features of the Frequency-......Page 378
12.5 State-Space Model Structure......Page 380
12.6 State-Space Model Identification in CIFERm Using DERlVlD......Page 385
12.7 Pendulum Example......Page 386
12.8 Identification of a XV-15 Closed-Loop......Page 388
12.9 Structural System Identification......Page 391
Problems......Page 395
13-State-Space Model Identification......Page 397
13.1 Background......Page 398
13.3 Equations of Motion for Flight Vehicles......Page 400
13.4 Model Formulation in a State-Space Structure......Page 404
13.5 Frequency-Response Database......Page 409
13.6 Checking the Initial Model Setup......Page 415
13.7 Model Identification and Structure Reduction......Page 416
13.8 Identification of Three-DOF LateraVDirectional......Page 417
13.9 Identification of Three-DOF LateraVDirectional......Page 432
13.10 Accurate Determination of Stability......Page 440
13.1 1 Identification of a Three-DOF Longitudinal......Page 444
13.12 System Identification of a six-DOF MIMO......Page 451
Problems......Page 468
14.1 Motivation for Time-Domain Verification......Page 471
14.2 Time-Domain Verification Method......Page 472
14.3 Estimating the Constant Bias and......Page 474
14.4 Correlation Problem......Page 477
14.6 Time-Domain Verification in CIFERB Using VERIFY......Page 478
14.7 Closed-Loop Transfer-Function Model Verification......Page 479
14.8 Bare-Airframe Model Verification......Page 480
14.9 Bare-Airframe Model Verification......Page 485
Problems......Page 487
15.1 Background and Literature on Identification......Page 489
15.2 Hybrid Model Formulation......Page 490
15.3 Hybrid Model Identification......Page 502
15.4 Lead-Lag Dynamics Identificatio......Page 528
Problems......Page 529
Appendix A-Summary of Suggested Guidelines......Page 533
References......Page 537
Index......Page 553
Supporting Materials......Page 563