part 5b - lateral autopilot

0

Lateral Autopilots

09/12/2015

1

Introduction

09/12/2015 Flight Control Systems

Autopilot uses:

For safety reasons

Lowers pilot workload (especially for long flights)

Types

Control or Hold certain flight parameter(s)

Perform navigational tasks

2

Introduction

09/12/2015 Flight Control Systems

3

Introduction

09/12/2015 Flight Control Systems

4

Lateral Autopilots Bank/Roll Angle Hold Coordinated Roll Angle hold

09/12/2015 Flight Control Systems

5

Bank Hold Autopilot

9/10/2012

6

Bank Angle Hold Prevents pilot having to constantly control roll angle.

Autopilot mode analysis/design, 2 important questions: Which type of control device do we use?

Ailerons

What type of feedback loop structure (sensor)? Roll Angle gyro

09/12/2015 Flight Control Systems

7

Bank Angle Hold In simplest form it is a wing leveler An Attitude Sensor, roll gyro, is used to sense deviation Bank Angle feedback gives positive stiffness in roll and

stabilize the spiral mode. If the aircraft is held at some other attitude other than

wing level, additional control systems must be used to control sideslip and pitch rate, so that a coordinated turning motion is produced.

This control system can provide the inner loop for other autopilots, e.g. to maintain Fixed Heading etc.

09/12/2015 Flight Control Systems

8

Bank Angle Hold Block Diagram

09/12/2015 Flight Control Systems

9

Bank Angle Hold Block Diagram

09/12/2015 Flight Control Systems

10

Bank Angle Hold

09/12/2015 Flight Control Systems

11

Bank Angle Hold

09/12/2015 Flight Control Systems

12

Bank Angle Hold

09/12/2015 Flight Control Systems

13

Bank Angle Hold

09/12/2015 Flight Control Systems

14

Bank Angle Hold

09/12/2015 Flight Control Systems

15

Bank Angle Hold

09/12/2015 Flight Control Systems

16

Bank Angle Hold

09/12/2015 Flight Control Systems

17

Bank Angle Hold

09/12/2015 Flight Control Systems

18

Bank Angle Hold

09/12/2015 Flight Control Systems

19

Bank Angle Hold

09/12/2015 Flight Control Systems

20

Bank Angle Hold

09/12/2015 Flight Control Systems

Spiral Mode (𝑇𝑇 < 10) Roll Mode (𝑇𝑇 < 0.2) Dutch Roll Mode (𝜁𝜁 > 0.1)

21

Coordinated Roll Angle hold Autopilot

9/10/2012

22

Coordinated Roll Angle hold

09/12/2015 Flight Control Systems

23

Coordinated Roll Angle hold

09/12/2015 Flight Control Systems

24

Heading Angle hold Autopilot

9/10/2012

25

Heading Angle hold Prevents pilot having to constantly control altitude during

the flight

Autopilot mode analysis/design, 2 important questions: Which type of control device do we use?

Rudder/Aileron

What type of feedback loop structure (sensor)? Sideslip Sensor, Gyro

09/12/2015 Flight Control Systems

26

Heading Angle hold

09/12/2015 Flight Control Systems

27

Heading Angle Hold

09/12/2015 Flight Control Systems

28

Heading Angle Hold

09/12/2015 Flight Control Systems

29

Heading Angle Hold

09/12/2015 Flight Control Systems

30

Heading Angle Hold

09/12/2015 Flight Control Systems

31

Heading Angle Hold

09/12/2015 Flight Control Systems

32

Summary For each Hold autopilot there are two important

questions: Which type of control device? Which type of feedback? loop structure? sensors?

Keep controller as simple as possible Proportional only (if acceptable) PD, PI, Lead/Lag, etc…

The closed loop system must comply with the airworthiness requirements

09/12/2015 Flight Control Systems

33

Summary Take into account the inner loop, when constructing the

outer loop. Keep in mind the possible effects on the closed loop

system of: Servo break frequency Flight condition (airspeed, altitude) etc...

09/12/2015 Flight Control Systems