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Tutorial 3 AEE3305 Flight Systems: Sensor Fusion & Kalman Filtering

1) One frequently used version of the constant acceleration family of dynamic models used in target tracking is
the white-noise jerk model given by,
𝑎̇ (𝑡) = 𝑤(𝑡)
a) What is the discrete-time state transition matrix for this model?
b) What is the full state-update equation?

2) From the definition of error covariance,


𝑃𝑘 = 𝐸[(𝐱𝑘 − 𝐱̂𝑘 )(𝐱𝑘 − 𝐱̂𝑘 )T ]
Derive the covariance update equation.

3) Considering a Kalman Filter tracking the error Δ𝑥 = (𝑥 − 𝑥̂) of estimate 𝑥̂ of the state 𝑥.
a) Sketch the block diagram for the output-injection state observer.
b) Show that the Kalman Filter error dynamics for a linear system are given by,
𝛥𝒙𝑘 = (𝐴 − 𝐾𝐶)𝛥𝒙𝑘−1

4) It is proposed that a Kalman Filter is designed to observe the states of the following system. Determine if
such an observer is possible by evaluating the observability matrix.
𝑥1 1 0 𝑥1 0
[𝑥 ] = [ ] [𝑥 ] + [ ]𝑢
2 𝑘 0 1 2 𝑘−1 1
𝑥1
𝑦 = [1 0] [𝑥 ]
2 𝑘

5) Assuming a stabilised platform, derive a two-state Kalman Filter that estimates the 1D position and velocity
of a vehicle taking 1D position measurements at 1Hz. Supposing:
• The initial position and velocity estimates are zero.
• The initial position and velocity uncertainties have standard deviation (SD) of 10 m and √10
m/s, respectively, and all covariances between states are initially zero.
• The first four position measurements are 212, 218, 232 and 241 m.
• The measurement noise uncertainty is √0.5 m SD and process noise has SD of 1 m and √0.1
m/s for position and velocity uncertainties.
What are the estimated position and velocity and their associated error covariance after 2s?

Tutorial 3 AEE3305 Flight Systems: Sensor Fusion & Kalman Filtering


University of Glasgow Singapore, last modified: 05/06/2024 1
6) Assume a Kalman Filter is used to estimate the dynamics of a simple 1D system with position and velocity
as the states. The matrices for state transition (𝐴), process & measurement noise covariance (𝑄, 𝑅), initial
conditions of the estimator (𝑥̂0 , 𝑃̂0 ) and measurement matrix (𝐶) are given by,
1 0.1 0 0
𝐴=[ ], 𝑄=[ ], 𝑅 = 0.1
0 1 0 0
0 1.0 0.1
𝐱0 = [ ] , 𝑃̂0 = [ ], 𝐶 = [1 0]
2 0.1 1.0
Using the equations for the Kalman Filter available in the data sheet,
a) Calculate the Kalman Gain 𝐾1 on the first iteration 𝑘 = 1.
b) Calculate the a posteriori state estimate 𝑥̂1 on the first iteration assuming a position measurement of
𝑦1 = 2.2.
c) Calculate the a posteriori error covariance matrix 𝑃1 after the first iteration 𝑘 = 1.
d) Using the Kalman Gain calculated in part (a), derive an equation for the error dynamics and determine
whether the observer will converge.

7) Sketch the block diagrams for a loosely coupled open-loop Kalman Filter used to provide an integrated
INS/GNSS solution.

Tutorial 3 AEE3305 Flight Systems: Sensor Fusion & Kalman Filtering


University of Glasgow Singapore, last modified: 05/06/2024 2

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