Aerospace and Electronic Systems Magazine July 2017 - 33
Pasand, Hassani, and Ghorbani
Table 7. Extended
No. Pulses
Linear Displacement (m)
Average
No.
Pulses per
Thruster
Mean
PW
(ms)
Conf. 1
333
137
Conf. 2
193
Conf. 3
Conf. No.
Standard Deviation (ms)
1*
Three
Axis
Fuel
Cons.
(kg)
2**
3***
x
y
z
110
20
10
665
665
−739
140
99
29
10
−15.9
6.1
3.1
17.3
1.27
195
138
100
30
10
10
−2
−3.4
10.8
1.25
Conf. 4
236
157
110
30
10
−16.1
9.7
7.2
20.1
1.50
Conf. 5
177
156
109
40
10
0.74
−1.6
1.5
2.3
1.23
Conf. 6
289
112
100
20
10
−2
−0.9
1.8
2.8
1.27
Conf. 7
178
109
100
30
10
12.9
13.2
−12.7
22.4
1.05
Conf. 8
199
113
100
50
10
−8.9
−9.5
8.6
15.6
1.23
Conf. 9
309
116
99
19
10
263
246
−248
Conf. 10
158
115
99
39
10
−1.8
0.1
0.2
1.8
0.90
Conf. 11
221
133
100
50
10
−2
−0.9
1.8
2.8
1.41
Conf. 12
224
130
100
50
10
6.5
7.6
−6.9
12.2
1.37
Conf. 13
174
116
110
30
10
−0.46
−0.20
0.37
0.62
1.04
Conf. 14
188
113
100
30
10
−0.73
−0.21
0.61
0.98
1.14
1,196
437
20.8
6.82
Conf., configuration; Cons., consumption.
* 68% of total data.
** 95% of total data.
*** 99.7% of total data.
of 0.047° and 0.046° on average, respectively. Afterward, configuration 10, with an accuracy of 0.051°, has the best performance. From Table 7, it is clear that there is no meaningful link
between the number of thrusters and the average of the three-axis
accuracy.
Thruster valves are exposed to erosion and corrosion when
they are opened and closed. To minimize thruster valve wear, it is
desirable to minimize the number of thruster firings by the PWPF
modulator. According to the table, the average number of pulses
per thruster is approximately proportional to the fuel consumption.
For example, while the fuel consumption of configuration 10 is
0.90 kg and its average number of pulses per thruster is 158, the
fuel consumption of configuration 4 is 1.5 and its average number
of pulses per thruster is 236. Consequently, selecting a configuration with less fuel consumption leads to a configuration with fewer
pulses, less wear, and a longer life cycle.
According to Table 7, configurations with four and six thrusters have wider pulses compared to configurations with more
thrusters. This makes sense, because fewer thrusters are employed to realize the required torques; therefore, the configuration needs to have wider working pulses. Based on the informaJULY 2017
tion, the minimum pulse width of the PWPF modulators is equal
to 10 ms, the same as the closed-loop sampling rate. In addition,
68% of pulse-width data, which lie within [−1σ, 1σ], are between
0 and 99 or 110 ms for all configurations. In Figure 5, the distribution of PWPF modulator pulse width is showed. Considering that the acceptable PWPF pulse width is 50 ms-because of
some cold-gas thruster design considerations-the percentage of
pulses in the acceptable range is shown above each figure. According to Figure 5, configurations 1 and 9 have fewer pulses
in the acceptable range. This percentage for other configurations
ranges from 85% to 95%.
With regard to the point that thrusters do not produce meaningful thrust in the coast phase, in general, linear displacement
is negligible in the coast phase compared to the firing phase,
which is supposed to apply more powerful thrusters. Regardless
of the mission, it can be claimed that increasing the number of
thrusters to 16 decreases the linear displacement considerably.
In addition, configurations 5, 6, 10, and 11 benefit from a low
value of linear displacement. It can be seen that configuration
1 and 9 have the worst performance from the aspect of linear
displacement.
IEEE A&E SYSTEMS MAGAZINE
33
Table of Contents for the Digital Edition of Aerospace and Electronic Systems Magazine July 2017
No label
Aerospace and Electronic Systems Magazine July 2017 - No label
Aerospace and Electronic Systems Magazine July 2017 - Cover2
Aerospace and Electronic Systems Magazine July 2017 - 1
Aerospace and Electronic Systems Magazine July 2017 - 2
Aerospace and Electronic Systems Magazine July 2017 - 3
Aerospace and Electronic Systems Magazine July 2017 - 4
Aerospace and Electronic Systems Magazine July 2017 - 5
Aerospace and Electronic Systems Magazine July 2017 - 6
Aerospace and Electronic Systems Magazine July 2017 - 7
Aerospace and Electronic Systems Magazine July 2017 - 8
Aerospace and Electronic Systems Magazine July 2017 - 9
Aerospace and Electronic Systems Magazine July 2017 - 10
Aerospace and Electronic Systems Magazine July 2017 - 11
Aerospace and Electronic Systems Magazine July 2017 - 12
Aerospace and Electronic Systems Magazine July 2017 - 13
Aerospace and Electronic Systems Magazine July 2017 - 14
Aerospace and Electronic Systems Magazine July 2017 - 15
Aerospace and Electronic Systems Magazine July 2017 - 16
Aerospace and Electronic Systems Magazine July 2017 - 17
Aerospace and Electronic Systems Magazine July 2017 - 18
Aerospace and Electronic Systems Magazine July 2017 - 19
Aerospace and Electronic Systems Magazine July 2017 - 20
Aerospace and Electronic Systems Magazine July 2017 - 21
Aerospace and Electronic Systems Magazine July 2017 - 22
Aerospace and Electronic Systems Magazine July 2017 - 23
Aerospace and Electronic Systems Magazine July 2017 - 24
Aerospace and Electronic Systems Magazine July 2017 - 25
Aerospace and Electronic Systems Magazine July 2017 - 26
Aerospace and Electronic Systems Magazine July 2017 - 27
Aerospace and Electronic Systems Magazine July 2017 - 28
Aerospace and Electronic Systems Magazine July 2017 - 29
Aerospace and Electronic Systems Magazine July 2017 - 30
Aerospace and Electronic Systems Magazine July 2017 - 31
Aerospace and Electronic Systems Magazine July 2017 - 32
Aerospace and Electronic Systems Magazine July 2017 - 33
Aerospace and Electronic Systems Magazine July 2017 - 34
Aerospace and Electronic Systems Magazine July 2017 - 35
Aerospace and Electronic Systems Magazine July 2017 - 36
Aerospace and Electronic Systems Magazine July 2017 - 37
Aerospace and Electronic Systems Magazine July 2017 - 38
Aerospace and Electronic Systems Magazine July 2017 - 39
Aerospace and Electronic Systems Magazine July 2017 - 40
Aerospace and Electronic Systems Magazine July 2017 - 41
Aerospace and Electronic Systems Magazine July 2017 - 42
Aerospace and Electronic Systems Magazine July 2017 - 43
Aerospace and Electronic Systems Magazine July 2017 - 44
Aerospace and Electronic Systems Magazine July 2017 - 45
Aerospace and Electronic Systems Magazine July 2017 - 46
Aerospace and Electronic Systems Magazine July 2017 - 47
Aerospace and Electronic Systems Magazine July 2017 - 48
Aerospace and Electronic Systems Magazine July 2017 - 49
Aerospace and Electronic Systems Magazine July 2017 - 50
Aerospace and Electronic Systems Magazine July 2017 - 51
Aerospace and Electronic Systems Magazine July 2017 - 52
Aerospace and Electronic Systems Magazine July 2017 - 53
Aerospace and Electronic Systems Magazine July 2017 - 54
Aerospace and Electronic Systems Magazine July 2017 - 55
Aerospace and Electronic Systems Magazine July 2017 - 56
Aerospace and Electronic Systems Magazine July 2017 - 57
Aerospace and Electronic Systems Magazine July 2017 - 58
Aerospace and Electronic Systems Magazine July 2017 - 59
Aerospace and Electronic Systems Magazine July 2017 - 60
Aerospace and Electronic Systems Magazine July 2017 - 61
Aerospace and Electronic Systems Magazine July 2017 - 62
Aerospace and Electronic Systems Magazine July 2017 - 63
Aerospace and Electronic Systems Magazine July 2017 - 64
Aerospace and Electronic Systems Magazine July 2017 - Cover3
Aerospace and Electronic Systems Magazine July 2017 - Cover4
http://www.brightcopy.net/allen/aesm/34-2s
http://www.brightcopy.net/allen/aesm/34-2
http://www.brightcopy.net/allen/aesm/34-1
http://www.brightcopy.net/allen/aesm/33-12
http://www.brightcopy.net/allen/aesm/33-11
http://www.brightcopy.net/allen/aesm/33-10
http://www.brightcopy.net/allen/aesm/33-09
http://www.brightcopy.net/allen/aesm/33-8
http://www.brightcopy.net/allen/aesm/33-7
http://www.brightcopy.net/allen/aesm/33-5
http://www.brightcopy.net/allen/aesm/33-4
http://www.brightcopy.net/allen/aesm/33-3
http://www.brightcopy.net/allen/aesm/33-2
http://www.brightcopy.net/allen/aesm/33-1
http://www.brightcopy.net/allen/aesm/32-10
http://www.brightcopy.net/allen/aesm/32-12
http://www.brightcopy.net/allen/aesm/32-9
http://www.brightcopy.net/allen/aesm/32-11
http://www.brightcopy.net/allen/aesm/32-8
http://www.brightcopy.net/allen/aesm/32-7s
http://www.brightcopy.net/allen/aesm/32-7
http://www.brightcopy.net/allen/aesm/32-6
http://www.brightcopy.net/allen/aesm/32-5
http://www.brightcopy.net/allen/aesm/32-4
http://www.brightcopy.net/allen/aesm/32-3
http://www.brightcopy.net/allen/aesm/32-2
http://www.brightcopy.net/allen/aesm/32-1
http://www.brightcopy.net/allen/aesm/31-12
http://www.brightcopy.net/allen/aesm/31-11s
http://www.brightcopy.net/allen/aesm/31-11
http://www.brightcopy.net/allen/aesm/31-10
http://www.brightcopy.net/allen/aesm/31-9
http://www.brightcopy.net/allen/aesm/31-8
http://www.brightcopy.net/allen/aesm/31-7
https://www.nxtbookmedia.com