The Development of Neural Network Based System Identification ...

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64 CHAPTER 3 AERIAL PLATFORM AND CUSTOM-BUILT FLIGHT TEST SYSTEM Vertical Arm Second Arm First Arm Pivot Centre Casters Figure 3.7 Translational functionality of the test stand. allows the helicopter to execute a full 6 DOF movement with limited work space. The safety test rig system could also be equipped with instrumentation sensors that provide position and orientation of the helicopter UAV. Such a system can provide the ability to test the controller continuously regardless of the weather conditions. Subsequently, the development of such device would also minimise the need for experienced helicopter pilots while conducting flight tests. 3.3.1 Design Concept of The Test Stand The final design of the test stand consists of two sections, one providing translation motion and while the other introducing rotational motion to the stand. Translation in the horizontal plane is achieved through the use of two jointed Selective Compliant Articulated Robot Arms (SCARA). The design offers faster motion response and lighter design than a comparable Cartesian system. Figure 3.7 shows the translational motion functionality of the designed test stand. The arms are mounted on a set of caster wheels which support the weight of the test stand. The first arm pivots off an anchor (a 15 kg steel weight) using deep groove ball bearings. The second arm pivots off the first arm, but it is longer than the first arm, and the helicopter is mounted such that it passes directly over the central pivot. Vertical translation motion is achieved using linear bearings, made from two drawer sliders, mounted perpendicular to each other. There is 500 mm of vertical travel. The
3.3 THE DEVELOPMENT OF TEST STAND FOR SAFE FLIGHT CONTROL TESTING 65 weights of the sliders, and of the pitch, roll and yaw joints, which are mounted at the top of them, are cancelled out by a counterweight. This means that the helicopter only has to lift its own weight, as if it was in free flight without the test stand. There are three stays which are attached to the top of the static part of the sliders, and to three points on the second horizontal arm. This gives rigidity to the sliders with minimal weight gain. The helicopter platform is joined to the test stand by the mount shown in Figure 3.8. Rotational motion is achieved by the pitch, roll and yaw joints in the test frame. This arrangement allows the helicopter to have a variable tilt around pitch, roll and yaw axis. In order to limit the roll and pitch rotation movements, the helicopter motion is constrained by a flexible cord joining the bottom of the helicopter mount to the base of the yaw arm. The cord prevents the combined angle of the pitch and roll from exceeding the maximum tilt angle. By altering the length of the cord the maximum tilt angle can be restricted to a smaller angle. The maximum tilt of the roll and pitch movements are set about 30 ◦ around pitch and roll axis. The yaw motion is constrained to approximately 450 ◦ due to cable twist issues. The pitch, roll and yaw arrangement consists of two sections; a ‘U’ shaped section and a bent section. Pitching motion occurs by a rotation between the helicopter mount and ‘U’ shaped section. The yaw motion occurs by the rotation between the bent section of the helicopter occurs by coupled rotation of the ‘U’ shaped to bent section and the bent section to the vertical member. The rotational joints (pitch, roll and yaw) can also be locked into to zero position with three solenoids. This is necessary for the zeroing of the instrumentation before testing and during the wind up phase of the helicopters rotors. During wind up phase, the rotor blades can be unstable and behave chaotically. The helicopter needs to be held in a steady position until steady rotation speed of the blades has been reached. The metal shaft of the solenoids is released via locking switch allowing the helicopter to tilt and yaw. In the first design of the test frame prototype, the solenoid shafts are returned back to their respective initial position by using elastic bands. Since the solenoids only allow single direction of movement, re-engagement process of the solenoids to lock the pitch, roll and yaw motion must be done manually by aligning the solenoid pins with
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The Development of Neural Network B
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ABSTRACT This thesis presents the d
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vii the MLP network, the prediction
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PUBLICATIONS The following is a lis
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xiv TABLE OF CONTENTS CHAPTER 4 CHA
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LIST OF FIGURES 1.1 Examples of typ
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LIST OF FIGURES xix 3.13 Overview o
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LIST OF FIGURES xxi 5.2 The predict
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LIST OF FIGURES xxiii 5.13 The pred
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LIST OF FIGURES xxv 7.1 The locatio
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LIST OF TABLES 3.1 The specificatio
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NOMENCLATURE AFCS Automatic Flight
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LIST OF TABLES xxxi NNARX QP RBF RC
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2 CHAPTER 1 INTRODUCTION Surveillan
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4 CHAPTER 1 INTRODUCTION is then de
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6 CHAPTER 1 INTRODUCTION the dynami
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8 CHAPTER 1 INTRODUCTION models [Sa
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10 CHAPTER 1 INTRODUCTION improved
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12 CHAPTER 1 INTRODUCTION Chapter 3
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4.3 SYSTEM IDENTIFICATION WITH NEUR
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4.4 SUMMARY 117 Segment 1 Segment 2
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Chapter 5 NN BASED SYSTEM IDENTIFIC
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5.2 OFF-LINE BASED SYSTEM IDENTIFIC
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5.6 ON-LINE SYSTEM IDENTIFICATION 1
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5.6 ON-LINE SYSTEM IDENTIFICATION 1
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5.7 MODEL PERFORMANCE COMPARISON US
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5.8 SUMMARY 151 methods such as wei
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5.8 SUMMARY 153 would enable the im
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156 CHAPTER 6 NEURAL NETWORK BASED
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Chapter 7 FLIGHT CONTROL SYSTEM DES
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7.2 FLIGHT TESTS IMPLEMENTATION 185
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7.3 EXPERIMENTAL RESULTS 187 1 0.8
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7.3 EXPERIMENTAL RESULTS 189 Longit
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7.3 EXPERIMENTAL RESULTS 191 Pitch
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7.3 EXPERIMENTAL RESULTS 193 Flight
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7.3 EXPERIMENTAL RESULTS 195 140 Ya
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7.3 EXPERIMENTAL RESULTS 197 indica
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7.3 EXPERIMENTAL RESULTS 199 20 100
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7.3 EXPERIMENTAL RESULTS 201 Yaw Ra
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7.3 EXPERIMENTAL RESULTS 203 mainta
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7.3 EXPERIMENTAL RESULTS 205 Yaw Ra
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7.4 SUMMARY 207 data measured from
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210 CHAPTER 8 CONCLUSIONS AND FUTUR
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212 CHAPTER 8 CONCLUSIONS AND FUTUR
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214 REFERENCES B. W. Bequette. Non-
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216 REFERENCES Konstantinos Dalamag
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218 REFERENCES Wayne Johnson. Helic
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220 REFERENCES B. Mettler, Mark B.
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222 REFERENCES V. R. Puttige and S.
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224 REFERENCES D.H. Shim. Hierarchi
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226 REFERENCES Nikos Vitzilaios and
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