The Development of Neural Network Based System Identification ...

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60 CHAPTER 3 AERIAL PLATFORM AND CUSTOM-BUILT FLIGHT TEST SYSTEM Forward Clockwise Rotation Bell Input Hiller Input Main Rotor Blade Stabilizer Bar β Stabilizer Bar Teetering Hinge Slider Wash-out Arm Swash-plate Roll Servo Input Pitch Servo Input Main Rotor Blade Stabilizer Bar Figure 3.4 The basic cyclic and collective pitch mechanism in the helicopter control system. β indicates the stabiliser bar flapping with respect to the body coordinate frame attached to the rotor hub. Symbol ‘◦’ indicates ball joints and fixed joints are shown as ‘•’. Figure adapted from Kim and Tilbury [2004]. blades is manipulated so that more lift is produced at the aft rather than the front of the rotor head. This tends to tilt the vehicle forward creating a forward component of force from the main rotor lift vector and thus creating forward motion. Similarly, a tilt of the swash-plate to the left causes more lift to be produced on the right than the left sides of the rotor disc. This asymmetry tilts the vehicle and moves it to the left. A tilt in any intermediate direction creates motion in that particular direction. The collective actuator moves the swash-plate up and down the rotor shaft and does not induce any tilt to the swash-plate. As the swash-plate moves up, the blade angle is increased by the same amount at all points through the cycle. This creates a uniform increase in lift across the disc with an overall increase in lifting force. In the TREX600 class helicopter, the motion of the collective actuator is achieved with a combination of three servomotors (120 ◦ Cyclic/Collective Pitch Mixing type) to push the swash-plate
3.2 AIR VEHICLE DESCRIPTIONS 61 up and down along the main rotor shaft. A total of three electrically powered Futaba S9252 and one JR 8900G actuators or control servos are used to position collective, lateral cyclic, longitudinal cyclic and tail rotor linkages. The rotation speed of the brushless DC motor is controlled through an electronic speed controller (ESC). A small rechargeable 4.8 V Type C 2000 mA h battery provides power to the actuators through a 2.4 GHz AR7000 Remote Control (RC) receiver located in the servo mounting frame. The receiver processes signals transmitted by a hand-held Spektrum DX7 transmitter on the ground and produces Pulse Width Modulated (PWM) output signals to drive the servos. The AR7000 receiver combines an internal and external receiver, which offers superior performance in comparison with conventional narrow band systems. The Spektrum radio system simultaneously transmits two frequencies which create dual RF paths, and this virtually makes the system immune to internal and external radio interference. The receiver may accommodate as many as 7 different actuators where the channel assignments are shown in Table 3.2. Table 3.2 RC receiver output channels Receiver Channel Output Description CH1 THRO Electric motor/Electronic speed control (ESC) CH2 AILE Collective/Cyclic pitch movement CH3 ELEV Collective/Cyclic pitch movement CH4 RUDD Tail rotor cyclic pitch movement CH5 GEAR Auxiliary Channel CH6 AUX1 Collective/Cyclic pitch movement CH7 AUX2 Rate Gyro Sensitivity Switching CH8 BATT Power Supply (5V) For the throttle, collective, lateral cyclic and longitudinal cyclic pitch, the receiver outputs are routed directly to the actuators/servos as shown in Figure 3.5. However, for the tail rotor cyclic pitch, the receiver output command is routed to a JR Angular Vector Control System (AVCS) G770 3D piezoelectric rate gyro which serves as a yaw damper. The yaw damper senses angular turn rate about the z-axis and uses this information to stabilise the helicopter in yaw motion. This feature allows the RC pilot to have better yaw control as all helicopters experience considerable cross-coupling
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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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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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