JPH06266417A - Work plan determining system - Google Patents

Abstract

PURPOSE:To easily tabulate SOE(Sequence Of Events) on the basis of a casual relation of each work, with regard to the work plan determining system of a system. CONSTITUTION:A generating/editing means 1 generates a Petri Net by a command from an operator and stores it in a storage means 2. Also, at need, according to a command from the operator, the Petri Net stored in the storage means 2 is read in and edited. An analyzing means 3 executes a net contraction by applying a net contraction rule to the Petri Net stored in the storage means 2, and also, executes an analytic processing such as reachable tree generation and deadlock verification, etc. A data conversion output means 4 allows the Petri Net stored in the storage means 2 to be subjected to data conversion to SOE, and outputs it to a display device 110 or a printer 120 as necessary. A simulation means 5 executes a plotting dislay by simulation onto the display device with respect to the Petri Net stored in the storage means 2.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a work plan determination method, and more particularly to a work plan determination method for determining a work plan of a system such as a spacecraft system.

Conventionally, in determining a work plan for a system such as a spacecraft system, SOE (Sequence Of Ev
A work process control table called ents) was created. This SOE is a line chart in which the start and end of each work (Events) such as the work on the orbit and the work on the ground corresponding to the time are sequentially described by taking time on the horizontal axis. Such work is usually started when a predetermined condition is satisfied. In addition, when the result of the started work or other predetermined conditions are satisfied, the next work is started, which is repeated.

[0003]

2. Description of the Related Art Conventionally, as one of the work plans of such a system, a mission of a spacecraft such as an artificial satellite is composed of a plurality of submissions by a plurality of companies and institutions. Moreover, because these submissions interfere with each other, tabulation is performed while taking into account various conditions such as ground control system work, satellite work information, manipulator orbit planning, and other orbit calculation data.

[0004]

However, the conventional SOE
In the table, it was necessary to do it manually while observing the above conditions and how each submission interferes. Moreover, if there was a change in mission or submission plan, it had to be restarted from the beginning. For this reason, there has been a problem in that considerable labor and time are required.

Further, the SOE does not describe interference information such as what is the condition for starting a certain work, and is a mere line chart. Therefore, the mission ends when one mission ends, so the technology is accumulated. There was a problem that the efficiency was low and the work plan know-how could not be used for the next work plan.

The present invention has been made in view of the above points, and it is possible to easily perform S based on the causal relationship of each work.
The purpose is to provide a work plan determination method that can be tabulated by the OE.

[0007]

FIG. 1 is a diagram for explaining the principle of the present invention for achieving the above object. The work plan determination method of the present invention is composed of respective elements of a creation / editing means 1, a storage means 2 and a data conversion output means 4.

The creating / editing means 1 is a Petri net.
Net) and edit as necessary. The storage means 2 stores the Petri net. Data conversion output means 4
Stores the Petri net stored in the storage unit 2 into S
The data is converted into OE and output to the display device 110 or the printer 120 as necessary.

[0009]

The creating / editing means 1 creates a Petri net in response to a command from the operator and stores it in the storage means 2. Further, the Petri net stored in the storage unit 2 is read and edited as needed according to a command from the operator.
After editing, it is stored in the storage means 2 as in the case of creation.

The Petri net thus completed is read from the storage means 2 by the data conversion output means 4,
Data is converted to SOE, and the display device 110 is used if necessary.
Alternatively, it is output to the printer 120.

Here, the theory regarding the Petri net will be described. "Petri Net" is the German mathematician Petri (Carl Adam) 196
It is one model of the discrete event system presented in 2 years. In this model, the relationship between the states corresponding to the conditions and events is described for the system. Here, the “state” means a situation in which a series of conditions are satisfied in the system. Therefore, an event corresponding to one state can occur, and the occurrence of the event causes a transition to a new state.

FIG. 2 is a diagram showing a basic model of a Petri net. In the figure, a Petri net is formally a 4-tuple N
= (P, T, I, O). P = {p1,
p2, ..., Pn} and T = {t1, t2 ,.
tn} is a disjoint finite set, and the element pi of P
{P1, p2, ..., pn} is replaced by "place (place
) ", And the elements ti {t1, t2, ..., Tn} of T are called" transitions ". In the relationship between the state and the event, the state corresponds to the place and the event corresponds to the transition.

I⊆P × T is an input binary relation,
Place set I defined for transition tεT
The element of (t) = {pi | pi It} is called "input place of t". Similarly, O⊆T × P is a set O (t) of places determined for the output binary relation transition tεT.
The element of = {pi | pi Ot} is called "output place of t".

By the way, the function M: P → N from the set of places to the set N of nonnegative integers is called “marking” of the Petri net, and the set (N, M) of N and M is “marked”. Called the Petri Net. The marked Petri net may be simply referred to as a Petri net. At this time, the place p i with the marking M is M (p i) tokens (token
)have. This M (pi) is called the "token number" of the place pi.

Next, the Petri net graph (Petri net graph) which expresses the relationship between the state of the Petri net and the event by a graph.
Net Graph). FIG. 3 is a diagram showing a basic unit of a Petri net graph in a marked Petri net. As a basic unit, the places p1, p
2, p3, transition t1 and directed graph (marked
graph) g1, g2, g3. In the figure, a directed graph g1 indicated by an arrow is drawn from a place p1 indicated by a circle toward a transition t1. Similarly, the directed graph g2 goes out from the place p2 toward the transition t1, and the directed graph g3 goes out from the transition t1 toward the place p3. Therefore,
The places p1 and p2 are input places, and the place p
3 is an output place.

Here, the marking is M = (M (p1),
If M (p2), ..., M (pn)), then a marked Petri net can be displayed by placing a token in any place p i. In the figure, one token tk indicated by a black circle is placed in the place p1. in this case,
M (p1) = 1. It should be noted that the transition t1 is M (p)> 0 for all pεI (t),
"It is firable."

Next, the firing of the Petri net will be described. 4A and 4B are diagrams showing firing of a marked Petri net, FIG. 4A showing before firing, and FIG. 4B showing after firing. The same elements as those in FIG. 3 are designated by the same reference numerals and the description thereof will be omitted.

In FIG. 4A, transition t1
The place p1 that is the source of the directed graphs g1 and g2 toward
When both M (p1) of p. And M (p2) of place p2 are 1 or more, the transition t1 is fired in response to a message from the operator. In the figure, place p
Since there are two tokens tk11 and tk12 in 1 and one token tk2 in the place p2, the transition t1 can be fired. At this time, if a message is received from the operator, it will fire.

In FIG. 4B, the tokens tk11 to tk11 from the place p1 and the tokens tk2 to tk2 from the places p2 are lost by firing, and a new token tk3 is generated in the place p3. Therefore, only the token tk12 remains in the place p1 and there is no token in the place p2.

Specifically, for example, the transition t1 represents an event that the machine starts to process a part, and a state that two parts arrive at the place p1 and one other part arrives at the place p2. It is assumed that the place p3 represents a state where the machine is working. Under this assumption, FIG. 4A shows the state of the machine before the start of machining,
FIG. 4B shows the state of the machine during processing.

Therefore, discrete events and states that interfere with each other are represented by connecting the required number of basic units of the Petri net, specifically the Petri net graph shown in FIG. The causal relationship can be expressed uniformly at various levels of the work plan. The SOE can be tabulated easily by converting the completed Petri net into SOE.

[0022]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is a diagram illustrating the principle of the present invention and a diagram illustrating an embodiment. The work plan determination method of the present invention comprises each element of a creation / editing means 1, a storage means 2, an analysis means 3, a data conversion output means 4 and a simulation means 5.

The creating / editing means 1 creates a Petri net in response to a command from the operator and stores it in the storage means 2.
In addition, the Petri net stored in the storage unit 2 is read and edited by a command from the operator as needed. After editing, it is stored in the storage means 2 as in the case of creation. Further, when creating and editing the Petri net, the Petri net can be hierarchized as described later.

The analysis unit 3 applies the net reduction rule, which will be described later, to the Petri net stored in the storage unit 2 to perform net reduction, and also performs analysis processing such as reachability tree generation and deadlock verification.

The data conversion output means 4 converts the Petri net stored in the storage means 2 into SOE data and outputs it to the display device 110 or the printer 120 as required.
The simulation means 5 draws and displays the Petri net stored in the storage means 2 on the display device 110 by simulation such as animation or a time chart.

Next, a device for carrying out the present invention will be described. FIG. 5 shows an EWS (Engineerin) for implementing the present invention.
(g Work Station) FIG. In the figure,
EWS100 is CPU101, ROM102, RAM1
03, hard disk I / F (interface) 1
04, HDD (hard disk device) 105, graphic control circuit 106, printer I / F (interface) 107, and communication I / F (interface) 1
It is composed of each element of 08.

The CPU 101 controls the entire EWS 100 according to the system program stored in the ROM 102. EPROM or EEPROM is used as the ROM 102. The creation / editing means 1, the analyzing means 3, the data converting / outputting means 4, and the simulating means 5 shown in FIG. 1 are all functions realized by the CPU 101 executing the system program stored in the ROM 102.

The RAM 103 stores various data such as data for creating, editing and analyzing a Petri net. The hard disk I / F 104 is an HDD for transferring data from the CPU 101 or the RAM 103 via the bus 109.
An interface for sending data to the CPU 101 or the RAM 103 by reading the data stored in the HDD 105 or the HDD 105. The HDD 105 stores various data such as a Petri net that should be retained even after the EWS 100 is powered off. RAM 103 or HD
D105 corresponds to the storage unit 2 shown in FIG.

The graphic control circuit 106 converts the digital signal output from the processor 101 or the like into a display signal and outputs it to the display device 110. A CRT or a liquid crystal display device is used as the display device 110.
The printer I / F 107 outputs data such as SOE output from the processor 101 via the bus 109 to the printer 120. The communication I / F 108 is another E
It controls the input / output of various data including data of Petri nets with WS and personal computers.

Next, the operation of the work plan determining method of the present invention will be described with reference to FIGS. 6 to 8. FIG. 6 is an example of a Petri net embodying the present invention, and is a diagram showing work at the time of launching an artificial satellite. In the figure, the Petri net is composed of 12 transitions and 19 places. Note that the 19 places are omitted here for the sake of simplicity.

The transition t11 is a transition t12 indicating a list-off event indicating the launch of a rocket or the like.
Is a satellite separation event that separates an artificial satellite from a launched rocket, transition t13 is a paddle check event that inspects the operating state of the solar array paddle, and transition t14 is a paddle deployment event that expands the solar array paddle. t15 is an SAR check event for inspecting the operating state of an antenna such as an S band antenna, and transition t16 is an SAR deployment event for expanding the antenna such as an S band antenna.
Reference numeral 7 indicates a paddle tracking event in which the solar cell paddle is directed to the sun, and transition t18 indicates a normal mode transition event in which the vehicle enters a orbit such as a geostationary orbit and operates.

The transition t21 is an orbit prediction event for predicting the flight orbit by calculating the position and velocity of the rocket or artificial satellite, and the transition t22 is an orbit for confirming that the position of the rocket or artificial satellite is in the planned orbit. Confirmation event, transition t23 is US NASA (Nati
onal Aeronautics and Space Administration) indicates an event of orbital element registration for registering the orbital operation of the artificial satellite, and a transition t24 indicates an event of orbital change for changing the orbit such as the geostationary orbit of the artificial satellite.

The created Petri net is stored in the storage means 2 of FIG. 1 and then converted into SOE by the data conversion output means 4. Data converted in this way S
The OE is as shown in FIGS. 7 and 8.

7 and 8 are views showing an example of the SOE after data conversion. FIG. 7 shows the transition t22 of FIG.
As a result of the orbit confirmation in Fig. 8, the SOE in the case where the orbit injection is normally operated is shown, and conversely, the SOE in the case where the orbit injection is not normally operated is shown.

In FIG. 7, the SOE 70 is divided into satellite event 71, operator job 72, and tracking system 73 work steps. In the satellite event 71, the work performed by the launched rocket and the artificial satellite is performed, in the operator job 72, the ground operator issues a command to the rocket and the artificial satellite, and the tracking system 73 responds to the command from the ground operator. Figure 6 shows the work performed by the paddle tracking system that directs the solar array paddle to the sun.
It is shown in chronological order corresponding to each transition of.

In this SOE 70, the operator job 7
As a result of the orbit confirmation 72a in 2, the orbit insertion is operating normally. Therefore, after performing the SAR check 72b,
The satellite event 71 has shifted to the paddle deployment 71a.

In FIG. 8, as in FIG. 7, the SOE 80 is divided into satellite event 81, operator job 82, and tracking system 83 work steps. The operations of the satellite event 81, the operator job 82, and the tracking system 83 are the same as those of the satellite event 71, the operator job 72, and the tracking system 73 shown in FIG.

In this SOE 80, the operator job 8
As a result of the orbit confirmation 82a in 2, the orbit insertion is not operating normally. Therefore, after performing the SAR check 82b, the orbit change 82c is performed, and the orbit element registration 82d and the SAR check 82e are performed again. Orbit change 82c
As a result, the satellite event 81 also changes its orbit 81a and then shifts to SAR deployment 81c. In this way, different SOEs can be obtained by fulfilling one event.

Next, a method for simplifying a complicated Petri net will be described. FIG. 9 is a diagram showing contraction of the net. In the figure, FIG. 9 (A) shows the reduction of the serial place,
FIG. 9 (B) shows a contraction of series transition, FIG. 9 (C).
Shows the reduction of the parallel place, FIG. 9D shows the reduction of the parallel transition, and FIGS. 9E and 9F show the case of removing the self-loop. Such reduction and removal is called "net reduction rule". The reduction of this net is executed by the analysis means 3 shown in FIG.

In the Petri net graph on the left side of the drawing of FIG. 9A, the place pa1 and the transition ta1 are shown.
And the place pa2 are connected in series in this order along the direction of the directed graph. The place pa1 receives two directed graphs and outputs one directed graph. Further, the transition ta1 receives the directed graph from the place pa1 and outputs the directed graph to the place pa2. Furthermore, the place pa2 is the transition ta1.
It receives two directed graphs in addition to the directed graph from and outputs two directed graphs.

The place pa1, the transition ta1 and the place pa2 are reduced to one place pa3 by the petri net on the right side of FIG.
It is a graph. The place pa3 receives four directed graphs corresponding to the directed graphs received in the places pa1 and pa2, and outputs two directed graphs corresponding to the directed graph output from the place pa2.

In the Petri net graph on the left side of the drawing of FIG. 9B, the transition tb1 and the place pb1
And the transition tb2 are connected in series in this order along the direction of the directed graph. Transition tb
1 receives two directed graphs and outputs three directed graphs. The place pb1 is the transition tb1.
And outputs the directed graph to the transition tb2. Furthermore, the transition tb2
Receives the directed graph from the place pb1 and outputs two directed graphs.

Such a transition tb1, place pb1 and transition tb2 are reduced to one transition tb3 in the Petri net graph on the right side of FIG. 9B. This transition tb3
Receives two directed graphs corresponding to the directed graph received at the transition tb2, and outputs four directed graphs corresponding to the directed graphs output at the transitions tb1 and tb2.

In the Petri net graph on the left side of the drawing of FIG. 9C, the transition tc1 and the place pc1
And the transition tc2 are connected in series in this order along the direction of the directed graph, and the place pc2 is connected in parallel to the place pc1. Transition tc
1 receives two directed graphs and outputs four directed graphs. Further, the place pc1 and the place pc2 are
Each receives the directed graph from the transition tc1, and outputs the directed graph to the transition tc2.
Furthermore, the transition tc2 receives two directed graphs in addition to the directed graphs from the place pc1 and the place pc2, and outputs two directed graphs.

Such a parallel place pc1 and place pc2 is contracted into one place pc3 in the Petri net graph on the right side of FIG. 9C. This place pc3 receives the directed graph from the transition tc1 and outputs the directed graph to the transition tc2.

In the Petri net graph on the left side of the drawing of FIG. 9D, the place pd1 and the transition td1
And the place pd2 are connected in series in this order along the direction of the directed graph. Further, a transition td2 is connected in parallel with the transition td1 between the place pd1 and the place pd2. The place pd1 receives two directed graphs and outputs four directed graphs. Further, the transition td1 and the transition td2 respectively receive the directed graph from the place pd1 and output the directed graph to the place pd2. Further, the place pd2 receives two directed graphs in addition to the directed graphs from the transition td1 and the transition td2, and outputs two directed graphs.

Such a parallel transition td1 and transition td2 are combined into one transition td3.
The Petri net graph on the right side of the drawing in FIG. This transition td3 receives the directed graph from the place pd1 and outputs the directed graph to the place pd2.

In the Petri net graph on the left side of the drawing in FIG. 9 (E), the place pe is set for the transition te1.
1 are connected in a ring shape and along the direction of the directed graph. That is, the transition te1 is a place p
It receives two digraphs in addition to the digraph from e1 and outputs two digraphs in addition to the digraph to the place pe1. In addition, the place pe1 receives the directed graph from the transition te1, and the transition t
Output a directed graph to e1.

Such a loop-connected place pe
Fig. 9 (E) shows that 1 is contracted to transition te2.
3 is a Petri net graph on the right side of the drawing. This transition te2 receives two directed graphs and outputs two directed graphs.

In the Petri net graph on the left side of the drawing of FIG. 9F, the place pf1 and the transition tf1
And are connected in a ring. That is, the place pf1
Receives two directed graphs in addition to the directed graph from the transition tf1, and outputs two directed graphs in addition to the directed graph to the transition tf1. Further, the transition tf1 receives the directed graph from the place pf1 and outputs the directed graph to the place pf1.

Such a loop-connected transition tf1 is reduced to the place pf2 as shown in FIG. 9 (F).
3 is a Petri net graph on the right side of the drawing. This place pf2 receives two directed graphs and outputs two directed graphs. By applying such six net contraction rules to the created Petri net, it is possible to simplify the original Petri net while preserving its boundedness and safety.

Next, the layering of nets will be described.
FIG. 10 is a diagram showing the hierarchization of nets. In the figure,
The upper layer Petri net graph is shown in FIG.
FIG. 10B shows a detailed Petri net of the lower hierarchy.
Graphs are shown respectively.

In the Petri net graph of FIG. 10A, the transition ta11, the place pa11, the transition ta12, and the place pa13 are connected in this order in a ring shape along the direction of the directed graph.
Further, between the place pa11 and the place pa13, a transition ta12 is connected in parallel with the transition ta12 along the direction of the directed graph.
Here, transition ta12 and transition t
Each a13 receives the directed graph from the place pa12 and outputs the directed graph to the place pa12.

A Petri net with such a connection
Regarding the graph, FIG. 10 shows a detailed Petri net graph of transition ta11, transition ta12, and transition ta13.
It is a Petri net graph shown in (B).

In the Petri net graph of FIG. 10B, the transition ta11 indicates that it is a Petri net graph connected by 6 transitions and 6 places as shown in the figure. Similarly, the transitions ta12 and ta13 indicate that they are Petri net graphs connected by 6 transitions and 4 places, respectively, as shown in the figure.

Thus, the Petri net is hierarchized into a plurality of hierarchies such as upper hierarchies and lower hierarchies by using the creating / editing means 1 shown in FIG. Further, one large work consisting of a plurality of transitions and places can be effectively utilized for the next work plan by accumulating it in the storage means or the like for each work unit and using it as know-how in the work plan.

In the above description, the present invention is applied to the SOE table in the work plan of the spacecraft system on the EWS 100. However, on each computer system such as a general-purpose computer or a personal computer, for example, each work such as urban development is performed. The same can be applied to tabulation of SOE based on causality.

Further, although the data-converted SOE is output to the display device 110 or the printer 120, it may be output to another EWS or host computer connected by a communication line.

[0059]

As described above, according to the present invention, the creating / editing means creates a Petri net in accordance with a command from the operator, stores it in the storage means, and edits it as needed, and the data conversion / output means writes data to the SOE. Since it is configured to convert and output, S is automatically output from the Petri net.
OE can be easily tabulated. Also, if there is a change in the plan, simply edit the corresponding Petri net and S
OE can be easily tabulated.

Further, by accumulating the Petri net in the storage means or the like, the know-how in the work plan can be effectively utilized in the next work plan.

[Brief description of drawings]

FIG. 1 is a diagram illustrating the principle of the present invention.

FIG. 2 is a diagram showing a basic model of a Petri net.

FIG. 3 is a diagram showing a basic unit of a Petri net graph.

FIG. 4 is a diagram showing firing of a Petri net.

FIG. 5 shows an EWS (Engineering Work S) for implementing the present invention.
FIG.

FIG. 6 is a diagram showing an example of a Petri net embodying the present invention.

[Figure 7] SOE (Sequence Of Events) after data conversion
It is a figure which shows an example.

FIG. 8 is a diagram showing an example of SOE after data conversion.

9A and 9B are diagrams showing reduction of a net, in which FIG. 9A shows reduction of a serial place, FIG. 9B shows reduction of a serial transition, FIG. 9C shows reduction of a parallel place, and FIG. Shows the reduction of the parallel transition, and (E) and (F) show the case of removing the self-loop.

10A and 10B are diagrams showing hierarchical layers of nets, in which FIG. 10A shows an upper layer and FIG. 10B shows a lower layer.

[Explanation of Codes] 1 creation / editing means 2 storage means 3 analysis means 4 data conversion output means 5 simulation means 110 display device 120 printer

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Shiro Nagashima 1015 Kamiodanaka, Nakahara-ku, Kawasaki City, Kanagawa Prefecture, Fujitsu Limited (72) Inventor Takashi Uchiyama 1015, Kamedotachu, Nakahara-ku, Kawasaki City, Kanagawa Prefecture, Fujitsu Limited ( 72) Inventor Yasushi Inamoto 1015 Kamiodanaka, Nakahara-ku, Kawasaki-shi, Kanagawa, Fujitsu Limited (72) Inventor Yoshiteru Nakamura 1015, Kamikodanaka, Nakahara-ku, Kawasaki, Kanagawa

Claims (5)

[Claims] 1. A work plan decision method for deciding a work plan of a system such as a spacecraft system, and a creating and editing means (1) for creating a Petri Net and editing it as necessary, and the Petri net. Storing means (2) for storing, and S the Petri net stored in the storing means (2).
A work plan determination method comprising: a data conversion output unit (4) for converting data into OE (Sequence Of Events) and outputting the data to a display device (110) or a printer (120) as necessary. 2. The work plan determining method according to claim 1, wherein the creating / editing means (1) is configured so that the Petri net can be hierarchized. 3. The method according to claim 1, further comprising analysis means (3) for applying a reduction rule to the Petri net stored in the storage means (2) to perform net reduction.
Described work plan determination method. 4. The analysis means (3) is configured to perform analysis processing such as reachability tree generation and deadlock verification of the Petri net stored in the storage means (2). The work plan determination method according to claim 3. 5. A simulation means (5) for displaying the Petri net stored in the storage means (2) on the display device (110) by a simulation such as animation or a time chart. The work plan determination method according to claim 1, which is characterized in that.