Lecture 4

Question 1

dynamic system

Answer 1

relates control inputs to the vehicle dynamic response (output), which might be influenced by disturbances

Question 2

output types

Answer 2

measurements and states

Question 3

states

Answer 3

translational velocity, angular velocity

Question 4

measurements

Answer 4

attitude angles, linear accelerometers, aerodynamic angles, pressure, temperature, GPS velocity and location

Question 5

problems in system theory

Answer 5

1. when output is unknown (simulation)
2. when input is unknown (control)
3. when model is unknown (system identification)

Question 6

system identification

Answer 6

development of a mathematical model for physical systems based on imperfect observations or measurements

concerned with the model structure determination and estimation of parameters

Question 7

synthesized model

Answer 7

1. simple enough to be useful
2. complex enough to capture important dependencies and features embodied in the observations or measurements

Question 8

simulation

Answer 8

concerned with the computation of system responses; numerical integration

Question 9

parameter estimation

Answer 9

concerned with the quantification of parameter values; statistical estimation of parameters

Question 10

must haves for data gathering

Answer 10

1. minimum sampling rate (twice the frequency of interest)
2. signal-to-noise ratio much higher than 1 (e.g. 10:1)
3. time-tagging of measurement channels

Question 11

types of sensors

Answer 11

basic aircraft systems, inertial sensors, GPS systems, air data sensors, control surface deflection, pilot forces / control inputs

Question 12

inertial systems

Answer 12

accelerometers, gyroscopes, angular accelerometers

Question 13

accelerometers

Answer 13

consist of proof mass, suspension holding the mass, pickoff providing a signal related to the acceleration

measure specific forces acting on the proof mass w.r.t inertial space; the proof mass gets deflected from its null position when accelerated

the gravitational acceleration on null mass should not be interpreted as acceleration by the accelerator

Question 14

gyroscopes

Answer 14

types: spinning mass (mechanical), optical ring laser gyro (RLG), fiber optical gyro (FOG), micro electro mechanical sensor (MEMS)

Question 15

Global Navigation Satelite System (GNSS)

Answer 15

measures the transmission time of an electro-magnetic signal from a transmitter to the user and multiplies this time with the speed of light, hence getting the distance

one satellite provides a sphere of possible positions, two provide two points, three provide one point

four satellites are needed to synchronise the receiver clock

Question 16

air data systems (ADS)

Answer 16

provide calibrated measurements of atmospheric conditions and the aircraft’s aerodynamic state: static pressure, total pressure, dynamic pressure, Mach number, airspeeds, angle of attack, angle of sideslip, air density, air temperature

Question 17

residual analysis

Answer 17

will show model deficiencies and any departure from the underlying assumptions

1. whiteness / independence test
2. graphical analysis
3. test for normality

Question 18

residual analysis - whiteness / independence test

Answer 18

computing estimate of autocorrelation function and comparing with theoretical result for white noise

a good model has residuals uncorrelated with past inputs

Question 19

residual analysis - graphical analysis

Answer 19

analyse residual plots

residual plots have to be purely random

Question 20

residual analysis - test for normality

Answer 20

if normally distributed measurement noise was assumed, check if the assumption is valid