A man-machine human
interface for a special
device of the pervasive
computing world
B. Apolloni, S. Bassis, A. Brega,
S. Gaito, D. Malchiodi, A.M. Zanaboni
DSI - University of Milano (I)
Outline



A procedure detecting attention states in car
driving
Fed by biologic input supplied through non
invasive sensors
Explains its output through a possibly
interpretable rule
The data




One subject using a car driver simulator
Subjected to alternate attention demanding
manoeuvres (fast lane exchange, pedestrian
avoidance) and relaxed driving
4 signals traced by a Biopac device (SKT,
GSR, ECG, RSP)
Collected by the School of Psychology,
Queen’s University Belfast.
Preprocessing

Extracted features




8 conventional (from medical knowledge)
FFT processing for ECG
Drift of the ECG signal from a neural prediction
SKT not considered (constant)
Feature processing I
t-1

15 Boolean values
are extracted from a
time-window of
width 3

Result of a Boolean
ICA through
minimization of
empirical entropy

t+1
n


zp j
(1zp j )
Ep  log  z pj (1 z pj )



j 1
253 connections (after pruning)

t
Feature processing II


Boolean values interpreted as propositional
variables
Minimal DNF and DNF on variables
interpreted as symbolic wavelets
Begin
DNF=ø;
for each positive example u;
DNF = DNF {m};
return DNF;
End
An obtained CNF
(x1+x3+x6+x8+x10+x14)(x1+x2+x5+x6+x7+x9+x11+x12+x13)(x1+x2+x6+x7+x9+x10+x12+
x14)(x1+x2+x5+x7+x8+x12+x13+x15)(x1+x3+x5+x11+x13+x15)(x3+x8+x10+x11+x13+x14+
x15)(x1+x2+x4+x6+x7+x11+x12+x13+x14+x15)(x1+x2+x4+x8+x12+x13+x14+x15)(x1+x2+x
3+x7+x8+x10+x13+x14+x15)(x3+x4+x8+x10+x13+x14+x15)(x1+x3+x6+x7+x8+x13+x14)(x3
+x5+x7+x8+x13)(x2+x3+x6+x7+x10+x11+x12+x13+x14)(x1+x5+x6+x8+x9+x11+x12+x15)(x
1+x5+x6+x8+x9+x11+x14+x15)(x3+x5+x7+x9+x10+x11)(x1+x3+x4+x7+x13+x14+x15)(x1+x
2+x3+x8+x11+x13+x14+x15)(x2+x5+x6+x7+x9+x11+x12+x15)(x2+x3+x4+x6+x9+x10+x11+
x12+x14)(x2+x4+x5+x7+x8+x13+x15)(x3+x4+x6+x7+x10+x13)(x3+x4+x6+x8+x10+x14)(x1+
x4+x7+x8+x13+x15)(x1+x4+x5+x7+x8+x9+x15)(x4+x7+x8+x10+x15)(x4+x7+x8+x10+x14)(x
2+x4+x5+x6+x7+x9+x10+x12+x13+x15)(x1+x3+x5+x8+x13+x15)(x1+x3+x6+x9+x10+x11+x
14)(x1+x6+x9+x10+x11+x12+x14)(x1+x6+x8+x9+x11+x12+x14)(x1+x2+x4+x6+x7+x10+x11
+x12+x13+x14)(x2+x4+x5+x8+x9+x10+x12+x13+x15)(x2+x4+x5+x7+x9+x10+x11+x12)(x1+
x3+x6+x7+x8+x10+x13)(x3+x4+x5+x6+x8+x9+x10+x11)(x2+x5+x6+x8+x9+x10+x11+x12)(x
2+x5+x6+x7+x8+x9+x11+x12)(x1+x2+x4+x5+x6+x7+x9+x12+x13)(x3+x4+x5+x7+x10+x11)(
x1+x2+x5+x8+x10+x12+x13+x15)(x1+x2+x6+x7+x9+x10+x11)(x1+x2+x5+x7+x8+x9+x14)(x
3+x4+x5+x8+x9+x10+x13+x15)(x3+x8+x9+x10+x11+x13)(x3+x9+x10+x11+x13+x14)(x1+x6
+x7+x8+x9+x10+x12)(x1+x2+x3+x6+x11+x13+x14+x15)(x2+x4+x5+x6+x9+x11+x12+x14+x
15)(x2+x6+x7+x10+x11+x12+x13+x15)(x2+x4+x6+x10+x11+x12+x14+x15)(x2+x5+x6+x9+x
10+x11+x12+x14+x15)(x3+x4+x6+x8+x11+x14+x15)
Post processing

Simplification of the learnt rules through
stochastic optimization of the cost
m
m
m
i 1
i 1
i 1
O f ,   1 Li  2    i  3  i  4 0


L: rule length, :rule radius, :disregarded
points
A simplified CNF
(x6+x11+x1+x13)(x10+x12+x9+x6)(x1+x13+x11+x5)(x3+x8+x6)(x4+x1+x13)(x12+x6+x
7+x13)(x13+x8+x9+x4)(x1+x6+x8)(x12+x6+x7+x8)(x1+x8+x5+x7)(x4+x6+x7+x13)(x7+
x9+x10+x11+x3)(x1+x8+x13+x15)(x3+x8+x13+x15)(x4+x7+x8)(x1+x6+x9+x10+x11)(x2
+x6+x11+x12+x15)(x3+x5+x8+x13)(x4+x5+x7+x10+x11)(x3+x9+x10+x11+x13)

From 403 to 81 literals
Performance I
DNF
Length
AVG
STDV


FP
CNF
FN
44.42 22.91 27.62
7.35
5.36
8.79
Length
FP
FN
71.06 22.41 28.22
20.37
7.49
50 cross-validation test
FP: false positives; FN: false negatives
5.44
Performance II
Length
DNF
44.42
Length
CNF
71.06
TP
FP
FN
72.38
22.91
27.62
TN
FN
FP
71.78
22.42
28.22
Performance III
Cones
Pedestrian
60
40
50
30
40
Center line
Steering
Acceleration
Brake
Continuos DNF result
Integral
30
20
10
0
1
3
5
7
9
20
10
0
1
2
3
4
5
6
7
8
9
10
11
12
13
14
-10
Center line
Steering
Acceleration
Brake
Continuous DNF result
Integral
11 13 15 17 19 21 23 25 27 29 31 33 35 37
-10
-20
-20
-30
Cones
Pedestrian
60
60
50
50
40
40
Center line
Steering
Acceleration
Brake
DNF frequency result
Majority Continuity
30
20
10
0
1
3
5
7
9
11 13 15 17 19 21 23 25 27 29 31 33 35 37
30
20
10
0
1
-10
-10
-20
-20
-30
2
3
4
5
6
7
8
9
10
11
12
13
14
Center line
Steering
Acceleration
Brake
DNF frequency result
Majority continuity