MATH36031 Project 2 - deadline 26th November 2021, time 1100hrs.
In this project, the dynamics between a fox and a rabbit will be investigated, by solving
differential equations modelling their positions at different times. The initial configuration
is shown in Figure 1, where the fox starts chasing the rabbit while the rabbit tries to escape
from its predator and moves towards its burrow. The fox is initially located at the origin
O(0, 0) and the rabbit is at (0, 800). There is a circular fence with an opening G at (0, 300).
The rabbit moves in a circular path of radius 800 with speed sr
1 towards its burrow. The
rabbit’s burrow is located at 800(sin(pi/3), cos(pi/3)). The path of the fox is initially directed
straight towards G with speed sf . After having reached the opening at G, the subsequent
path the fox takes in trying to catch the rabbit depends on whether its view of the rabbit is
blocked by the straight line fence between A and E or not, as follows:
ˆ if the rabbit is in sight, the fox’s attack path points directly towards the rabbit (the
direction of the velocity vector of the fox is exact from the fox to the rabbit);
ˆ if the view of the rabbit is blocked by an inpenetrable straight line fence AE, see figure
1, then the fox runs directly towards the corner A and once having reached A its attack
path points directly towards the rabbit. The coordinates of AE are A(350, 620) and
E(550, 300).
1The subscripts f and r denote the fox and rabbit respectively. The units of the coordinates are metres.
G
A
C C
O
E
Burrow
Figure 1: Schematic diagram showing the geometry and obstacles with O denoting the origin
of coordinates. There is a circular fence C with a small opening at G (0, 300). There is
a fence at AE with A (350, 620) and E(550, 300). The dashed green line shows the path
followed by the rabbit towards it burrow. The dashed-dotted red line shows the initial path
of the fox.
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Question 1: Constant speeds.. Assuming that both the fox and the rabbit run with
constant speeds sf = sf0 = 16m/s and sr = sr0 = 13m/s respectively, determine whether
the rabbit can be captured before it reaches its burrow. The rabbit is considered to be
captured by the fox, if the distance between them is smaller than or equal to 0.1 meter.
Question 2: Diminishing speeds. Let us consider a more realistic scenario, when
the hungry fox meets the tired rabbit. Because neither the fox nor the rabbit are in their
best conditions, their chasing/escaping speeds diminish in time, according to the amount of
distance (starting from the time they find each other and start running) they have travelled
so far. More precisely, their speeds at time t are given by
sf (t) = sf0e
−µfdf (t), sr(t) = sr0e−µrdr(t),
where sf0 = 16m/s and sr0 = 13m/s are the same initial speeds as above, µf = 0.0002m
−1
and µr = 0.0008m
−1 are the rates of the diminishing speeds, df (t) and dr(t) are the distance
they have travelled up to time t(> 0). Determine whether the rabbit can be captured before
it reaches its burrow. (You may assume that this diminishing speed starts from t = 0).
Outputs required You are required to submit a report (maximum 8 pages including
any appendices) in pdf form via the submission box on Blackboard. Additionally you need
to submit your m-files used for the MATLAB codes. As part of the required output, the
times and locations of the events happening need to shown (eg, the time and location where
the fox catches the rabbit, or the time it takes for the rabbit to escape and the location of
that fox at that time). A graph of the paths taken by the fox and rabbit during the chase
should be given.
Additional information and guidelines
1. All coding must be done in MATLAB.
2. Treat both the fox and the rabbit as points, without worrying about their finite sizes
(as in most models).
3. The questions can be answered with different approaches, but the preferred way is to
use the built-in ODE solver ode45 discussed during the lectures.
4. Avoid using hard-coded numbers. Any number in your code should either be given as
initial condition, or be derived from these conditions.
5. Keep to the page length not exceeding eight A4 pages, and there is no need for a title
page or abstract for a relative short report like this. Font sizes should be no smaller
than 11 point, and page margins no smaller than 2cm.
6. List the complete code of the whole function at the end of each question, or in an
appendix. Make your source code more readable, by keeping the indentation and
stylistic features, and can be copied from your submitted. Your published results
should be reproducable from the code attached.
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7. Have a look at the generic rubric about how your report will be marked, and also the
intended learning outcomes about what you are expected to achieve in the end.
8. Avoid copying (too many) sentences directly from the project description, and try to
restate the problem with your own words or examples if possible.
9. You may use your report in the future as evidences of written work, so take it seriously.
10. Your target audience is a fellow student on your course: explain the questions so that
the report can be understood without this project description and your approach could
be implemented in another computer language like Python. The report should indicate
to the reader how well you understand the problem and the approach you took. Your
goal will be to communicate your solutions to another person rather than to show
you’ve completed the assignment.
11. Balance the explanation of the approach and the comments in the code. Avoid under-
commenting and over-commenting.
12. Aim for precision and clarity of writing.
13. Since there is no final exam, you are advised to spend at least 15 hours on each project,
with additional self-study if you are less experience with computer programming. Re-
member for a 10 credit module like this one, you are expect to spend 100 = 10 Ö 10
hours in total (including lectures, labs, self-study and coursework).
14. Please do not put any personal information on the report, only your student ID number.
15. The submission for each project will be open two weeks before the deadline. Only
your last submission will be marked, and anything submitted after the deadline will
be treated late and any penalty will be applied by the Teaching and Learning Office
in June according to the Undergraduate Student Handbook.
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