Control and Signal Processing (ECS 2002)
Singapore, December 9-12, 2002
Dear Sirs,
We send you a summary and report “Methodology of development of high-tech profitable Mission Control Center for automatic space vehicles” and "Peculiarities of spacecraft “Ocean-O” control in geomagnetic storms".
Authors are Udaloy V.A., Ivanov N.M., Sokolov N.L., Pazdnikov V.U.
We ask you to find opportunity to include this report in conference work.
Contact telephone number: (095) 513-44-64, Sokolov N.L.
Fax: (095) 586-84-34, Sokolov N.L.
First deputy director
of Mission Control Center V. A. Udaloy
Methodology of development of high-tech profitable Mission Control Center for automatic space vehicles
Udaloy Valeriy Alekseevich, Ivanov Nikolay Mihailovich, Sokolov Nikolay Leonidovich, Pazdnikov Vladimir Urievich
Mission Control Center and Modeling of Central Scientific and Research Institute of machinebuilding, t. Korolev, Moscow region, Russia.
Summary
There are various Mission Control Centers (MCC) in many countries. But analysis of the existing literature proves absence of general idea of MCC structure optimization although optimal structure of MCC could allow to increase profitability of mission control.
The base of methodology is principle of center link allocation in general MCC structure – it is mission control section, where all decisions about space vehicles (SV) mission control are made. Other impotent principle is development of high-tech universal hardware-software means, which could be used for almost any SV control.
MCC structure is formed as hierarchical system, which includes following levels: making of decisions, self-organizing, adaptation, reception and calculation of data.
Global and local purposes of hierarchical system structure optimization are formulated, algorithms of a number of managing influences forming, which provides optimal interaction between separate elements of MCC, is submitted.
Key words:
Modeling, Control operations, Optimization, Methods, Hierarchical systems, spacecraft.
1. Introduction
Modern civilization development is accompanied by development and use of various space systems for commercial and scientific purposes to provide vital functions and increasing needs of people. Space systems of remote probe of the Earth play a special role among such systems. Orbital segment of this systems is set of low-orbit space vehicles (SV), Which make interactive coordinated movement and accomplish with certain periodicity survey and observation of the earth surface in various spectral ranges. Information, received from SV is vital and constantly used in various fields of national economy.
At present there are various Mission Control Centers (MCC) in many countries. Some methods of development of some MCC subsystems, hardware-software means, of forming of operative groups for V control are known. But analysis of the existing domestic and foreign literature proves absence of general idea of MCC structure optimization.
Basing on general theory of hierarchical managing systems questions about development of mathematical model describing researched process and methodology of such processes optimization are considered in this work. It is known that in development of models and methods of MCC structure optimization basic complexity is connected with processes taking place in separate elements of large managing system, depend on different technical, organizational, information and other factors.
The base of methodology is principle of center link allocation in general MCC structure – it is mission control section, where all decisions about SV mission control are made. Other impotent principle is development of high-tech universal hardware-software means, which could be used for almost any SV control.
2. MCC hierarchic structure characteristics
Developing models of MCC functioning we used the following laws of hierarchical managing systems structure:
§ consecutive vertical arrangement of subsystems forming appropriate hierarchy;
§ priority of actions or top level subsystem right intervention in actions of lower level subsystems;
§ dependence of top level subsystem actions on actual execution of lower level subsystems functions;
§ management tasks of top levels contains more vagueness and it is harder for mathematical formalization that complicates search of optimal decisions;
§ in practice top level subsystem intervene in lower level subsystems work occurs only in contingency, it means that structure is changed only if system characteristics are worsened up to such degree that correction is necessary.
Basing on listed principles hierarchical MCC structure could be submitted as centralized structure with independent management. Feature of such structure is combination of centralized hierarchical system management accomplished by controller with local separate subsystems management accomplished by appropriate subsystem controller.
Research contains two stages. At the first stage distribution optimization of system functions performance between its separate elements and purposes coordination and optimization of various level subsystems interaction were carried out. At the second stage preliminary analysis of alternative variants of MCC structure was accomplished. As a result of basic or general management functions synthesis optimal hierarchical system structure is defined.
Following hierarchical levels were allocated:
§ the top level (decision making level) – coordinate all actions on SV control so to accomplish main objects of control. These functions are performs by central control section, which includes: chief of SV control, technical chief of SV control, representatives of organizations participating in SV control;
§ the second level (self-organizing level) – choose criteria and algorithms used on lower levels to insure basic conditions of performing main objects of control. These functions are performs by groups of planning and on-board facility capacity analysis;
§ the third level (adaptation level) – performs concrete definition of a number of vagueness for top level subsystems by examining external influences and definition of algorithm type or parameters for lower level work. These functions are performs by groups of ballistic-navigation, telemetry and command-program software;
§ the fourth level (receiving and calculating flight data level) – defines method of subsystem elements actions according to initial information about external environment and command algorithmic instructions of top level subsystems. These functions are performs by groups of receiving telemetry, current navigation parameters, return channel information, standard ballistics calculations, command-program information files, on-board systems operating time calculations, etc.
3. Methodic of calculating
For analysis of basic features of management we give mathematical description of functioning of whole MCC system and its subsystems and describe general method of optimal hierarchical system structure.
Designations:
C1 – the first coordinating level subsystem;
C2i (i=1, 2,…, n), C3j (j=1, 2,…, m), C4k (k=1, 2,…, l) – set of the second-, third-, fourth level subsystems accordingly;
P – managed process;
m Є M – a number of managing signals;
ω Є Ω – a number of external influences;
r Є R - a number of information signals sent by MCC subsystems;
s Є S - a number of coordinating signals;
y Є Y - a number of target signals;
k Є K - a number of information signals sent by subsystem C1.
System functioning model is submitted in terms of set theory.
Managed process:
P: M x Ω → Y
Coordinator model:
C1: K → S
Management subsystem S functioning model (s= 2, 3, 4):
Cs: S x Rs → Ms
Information feedback of all levels:
f1: S x R x M → K
fs: Ms x Ω x Y → Rs
At analysis of features of system functioning and management principles the main tasks of optimal management are general management task and local lower levels management tasks.
Global task of optimization is basic purpose of hierarchical system management and means: determining such number of managing signals m Є M at which global special function (g (m) = G [m, P (m)]achieves the minimum.
Considering local optimization tasks we suppose that managed process P contains a number of sub-processes Ps (s=1, 2, 3, 4) cooperating between themselves and every sub-processes is managed by lower level Cs controller.
Sub-process Ps interaction with others is accomplished via a number of connections. Ds – local optimizational task solving by controller S of lower level, and local optimizational function of this task solving quality is:
gs (ms, us) = G [ms, Ps (us, ms)], where Ms x Us – a number of function tasks.
Coordination principles are the central part of hierarchical management system development. There are two methods of influences on local optimization tasks from top level subsystem:
§ through quality function Gs by changing management tasks;
§ through changing parameters of a number of connections in certain sub-processes class Ps.
The first method supposes taking not one, but a lot of local quality functions, and as a result coordinating signal Ss is directed on choice of appropriate quality function from given number of management systems S. In case there is no opportunity for coordination by purpose changing, coordination by limits changing basing on either principles of interaction interrupting or interactions forecasting Us should be used.
Interaction interrupting principle supposes every lower management controller solving its task gets right to consider connecting inputs Us as additional variables which it from own local criteria. In case management tasks that need solving are determined as if lower elements and sub-processes were absolutely independent.
Interaction forecasting principle supposes coordinating signals Ss to contain information about forecast values of connections Us that occur during issuing managing influences.
So offered methodology allows forming a number of managing influences issued on every hierarchical system levels and to accomplish comparative analysis of alternative variants of MCC structure.
4. Conclusion
Research problem of MCC structure optimization methodology development is requirement of MCC profitability increasing by definition of optimal structure and interaction between various hierarchical management system elements.
Correctness of received methods is confirmed during MCC-M development for automatic SV “Ocean-O” and “Meteor-3M” (town Korolev, Moscow region).
REFERENCES
[1] Udaloy V. A. Current state and basic peculiarities of the Mission Control Center of the Central Science-Research Institute of Machinebuilding. Bulletin of Cosmonautics academy. Samara. 1998.
[2] Vishnyakova L.V. Development of decomposition methods of optimal designing of complicated technical systems, basing on mathematical modeling. Theory and management systems, N4, 1995.
[3]Ivanov N.M., Sokolov N.L., Udaloy V.A. Methodology of structure optimization of Mission control center for multipurpose spacecraft, basing on general theory of hierarchical management systems. Report of machinebuilding section of Russian science academy. 1999.
Peculiarities of spacecraft “Ocean-O” control in geomagnetic storms
Udaloy Valeriy Alekseevich, Ivanov Nikolay Mihailovich, Sokolov Nikolay Leonidovich, Pazdnikov Vladimir Urievich
Mission Control Center and Modeling of Central Scientific and Research Institute of machinebuilding, 141070, t. Korolev, Moscow region, Russia.
Summary
Russian-Ukraine spacecraft “Ocean-O” (S/C) was launched on July, 17, 1999. S/C is controlled from Mission Control Centre and Modeling (MCC-M), town Korolev, Moscow region.
Purpose of the S/C “Ocean-O” is operative reception of Earth and World ocean remote probe information.
After the launch the control group came across complexity of S/C attitude control. In condition of atmosphere density difference control system nominal work turned out to be impossible because of lack of flywheel uncharge by electromagnetic plant in tangage channel.
Russian-Ukraine commission suggested and the control group accomplished unique scheme of S/C attitude control. The main idea of this scheme is performing periodic correction of the solar array position during communication session by issuing discrete commands to make necessary aerodynamic and gravitational moments combination that compensates disturbing moment. To support energy balance limits on angle of solar array turning were taken into consideration.
Analytic dependences were come out by input a number of simplifications into general system f differential equations, that describe the change dynamics of kinetic moment of flywheel. This dependences help to determine solar array inclination angle to provide necessary aerodynamic and gravitational moments combination.
Using such scheme turned out to be effective in S/C control in geomagnetic storms (July, 15-16, 2000; March, 30-31, 2001; November, 24-25, 2001). It is worth to note that during the geomagnetic storm on July, 15-16, 2000 Japanese X-Ray Telescope, that had worked on orbit since 1993 and studied black holes and other distant astrophysical objects, spun out of control.
Key words:
Control, Spacecraft, Modeling, Geomagnetic storms, Aerodynamic moment, Solar Array.
1. Introduction
Russian-Ukraine spacecraft “Ocean-O” (S/C) was launched on July, 17, 1999. S/C is controlled from Mission Control Centre and Modeling (MCC-M), town Korolev, Moscow region.
Purpose of the S/C “Ocean-O” is operative reception of Earth and World ocean remote probe information.
After the launch the control group came across complexity of S/C attitude control. In condition of atmosphere density difference control system nominal work turned out to be impossible because of lack of flywheel uncharge by electromagnetic plant in tangage channel.
Russian-Ukraine commission suggested and the control group accomplished unique scheme of S/C attitude control. The main idea of this scheme is performing periodic correction of the solar array position during communication session by issuing discrete commands to make necessary aerodynamic and gravitational moments combination that compensates disturbing moment. To support energy balance limits on angle of solar array turning were taken into consideration.
2. Task
Research is based on using general differential equation, that describes the change dynamics of kinetic moment of flywheel H in tangage channel [1-3].
(1)
Where M – summary external moment acting in tangage channel, w – rate of the S/C spinning in tangage channel.
Some simplifications that fit to nominal S/C work were made:
§ rates of S/C in relation to its center of mass are near to zero;
§ summary external moment M is considered to be constant at limited time periods and flight periods with constant position of solar array inclination angle;
§ aerodynamic moment changes value abruptly during solar array turning.
Note, piece constancy of summary external moment helps to increase accuracy of calculations in condition of atmosphere density difference by phased recalculation of value M.
By differential equation (1) reform following analytic dependences were come out to determine solar array inclination angle to provide necessary aerodynamic and gravitational moments combination in tangage channel.
3. Algorithms of control
To get some necessary value of kinetic moment H (t)=H2 the angle a determining solar array position, is calculated with the following formula (angle a is zero if solar array is transversely to oncoming blast and increase during solar array turning anticlockwise):