A DEVICE FOR REAL TIME STIMULATION

Abstract: A device is described for simulating in real time the position of a possibly fictitious object in a three-dimensional coordinate system, comprising at least a first unit and a second unit. Each unit is provided with a GPS-receiver (2) for receiving position and timing signals respectively from at least four satellites, furthermore with a transmitter/receiver for communication between the first and second units and a communication computer (6) having memory capacity and connecting the GPS-receiver (2) and transmitter/receiver (4). The device is in particular characterized in that at least the first unit contains a simulation computer (7) communicating with the communication computer and simulating the position in the coordinate system and in time of said object and communicating this information to the second unit and the that the communication computer (6) is arranged to control the communication through the transmitter/receiver (4) according to the STDMA-method.

Description: A device for real-time simulation The present invention relates to a device for real-time simulation of the position of a possibly fictitious object in a three-dimensional coordinate system, comprising at least a first unit and a second unit, each one provided with a GPS-receiver for receiving position and time signals respectively from at least four satellites, furthermore a transmitter/receiver for communication between the first and second unit, preferably within the VHF- or UHF-radio frequencies, and a communication computer having memory capacity which connects the GPS-receiver and the transmitter/receiver. Since a long time various devices for military simulation of battle simulations are used, for example it can be concerned with laser methods for simulating realistic paths of projectiles. Then usually, the considered projectiles have been fired from a vehicle located on the ground to a target, also located on the ground. However, there has been a lack of devices which at a reasonable cost simulate battle situations in which at least one part is located in space. This is even more true in those cases when the two parts are located there. In recent years the appearance of GPS-systems, i.e. Global Positioning Systems, which include satellites, the position of which in relation to the earth is accurately determined, has resulted in possibilities of a very accurate determination of the position, also of objects in space. The object of the present invention is thus to provide a device of the kind which is mentioned in the introduction and which is suited to many applications and has a relatively low cost when used. According to the invention such a device is primarily characterized in that at least the first unit contains a simulation computer communicating with the communication computer and simulating the position in the coordinate system and in time of said object and communicating this information to the second unit. Such a device works well in the case where the number of objects is limited, i.e. if not more than some 3 - 4 objects are considered. However, a method developed in recent years, the so called STDMA, i.e. "Self-organizing Time Division Multiple Access", allows, as applied in the actual context, that a very large number of objects can participate in the simulation. This method is described in the International Patent Application PCT/SE92/00485 having the publication number WO 93/01576, published 21 January 1993, and in other documents. In a preferred embodiment of the invention thus the communication computer in the first and second units is provided with a time base which is exactly controlled by timing signals from said satellites, said time base defining time blocks, which are standardized, are capable of being numbered and form a common, exact and predetermined repeated maximum frame, and furthermore with means for using a free time block in each maximum frame, and for automatically therein transmit a position signal between transmitter and receiver using the selected radio frequency. The details of the STDMA-method are exhaustively described in said International Patent Application and is only described in a summarizing way in the present context. However, the device according to the invention can be also used for collision warnings between at least a first unit and a second unit, in civil and military contexts. In that case the device is characterized in that the simulation computer of the first unit both simulates the position of the first unit in the coordinate system and in time to a first table and also simulates, as guided by data communicated as to position and time for the second unit, the position of the second unit in the coordinate system in time to a second table, whereupon the simulation computer compares the first and the second tables and issues, for agreeing data as to position and time, a warning signal. The invention is in the following described in greater detail with reference to the accompanying drawings, in which Fig. 1 shows a principle diagram of a unit in the device according to the invention, Fig. 2 shows a principle diagram of a simulation computer, and Fig. 3 schematically illustrates the use of the device. In this context a unit according to the invention is called a transponder, and it is in Fig. 1 denoted by 1. It contains a GPS-receiver, denoted by 2, for receiving through an antenna 3 position and timing signals respectively from at least four satellites, in practical cases still more satellites. The GPS-system is supplemented with transmitters positioned on the ground in order to achieve full performance. Furthermore, in the transponder a digital transmitter/receiver 4 is included for communication through an antenna 5 between this unit and other units, i.e. transponders, in this case within the VHF- or UHF-radio frequencies. A communication computer 6 having memory capacity is connected to the GPS-receiver 2 and the transmitter/receiver 4. A simulation computer 7 is connected to the communication computer. Input terminals of the latter and the simulation computer are denoted by 8. The communication computer is arranged to control the communication through the transmitter/receiver 4 according to the STDMA-method mentioned above. A repeated maximum time frame is schematically illustrated at the numeral 9. It comprises in the example illustrated 60 seconds, divided in 9000 time blocks, one of which being denoted by 10, each block thus comprising 6.67 ms. As described in greater detail in the cited International Patent Application PCT/SE92/00485 a large number of transponders can communicate their positions through an automatic allocation of the time blocks. The construction of the simulation computer, i.e. its simulation protocol, is schematically illustrated in Fig. 2. The simulation core consists of a numerical integration schedule having six degrees of freedom, both for continuous and discrete dynamic systems. Data such as position reports from the communication computer are stored in an event input list denoted by 12. The event handler 13 is an input filter through which events pass before being processed in the simulation core. The model library 14 contains specific information on the simulation objects, e.g. robots such as Sidewinder, AMRAAM, RBS-15, Maverick, etc. The event output list 15 transmits data to the communication computer 16. In Fig. 3 a first aircraft is denoted by 16 and a second aircraft is denoted by 17, which are both provided with devices according to the invention, i.e. transponders. The first aircraft then continuously receives in real-time information on the path 18 of the second aircraft in the three-dimensional coordinate system. In the transponder of the first aircraft now a firing of a robot along a path 19 is simulated, which is calculated to result in hitting a robot at a point 20 of impact. The information on the path 19 is transmitted to the transponder in the second aircraft and the pilot therein will, as guided by the information, change his path, so that a hit is avoided. The first aircraft then deviates along a path 21. Fig. 3 can also illustrate the use of the device for collision warnings. In that case the two airplanes transmit through their transponders information to each other on their path in the three-dimensional coordinate system, as simulated forwards in time, so that the simulation computer of each transponder stores first and second tables listing the positions of the own aircraft and of the other aircraft respectively in the three- dimensional coordinate system in time, which data are illustrated by the paths 18 and 19. By comparing the position and time data found in the two tables in the simulation computer it issues a warning signal in the case of agreeing position and time data (as is indicated by the numeral 20 in Fig. 3) and issues a warning signal, so that at least one of the aircrafts can change its path, as indicated by the numeral 21 in Fig. 3.

Claims: Claims 1. A device for simulating in real-time the position of a, possibly fictitious, object in a three-dimensional coordinate system, comprising at least a first unit and a second unit, each one provided with a) a GPS-receiver (2) for receiving position and timing signals respectively from at least four satellites, b) a transmitter/receiver (4) for communication between the first and second units, preferably within the VHF- or UHF-radio frequencies, and c) a communication computer (16) having memory capacity and connecting the GPS- receiver (2) and the transmitter/receiver (4), characterized in that at least the first unit contains a simulation computer (7) communicating with the communication computer (6) and simulating the position in the coordinate system and in time of said object and communicating this information to the second unit and that the communication computer (6) is arranged to control the communication through the transmitter/receiver (4) according to the STDMA-method. 2. A device according to claim 1, characterized in that the communication computer (6) in the first and second unit is provided with a) a time base accurately controlled by timing signals from said satellites, said time base defining timing blocks which are standardized, capable of being numbered and form a common, exact and predetermined repeated maximum frame, b) means for using a free time block in each maximum frame and for automatically therein transmit a position signal between the transmitter and the receiver using the selected radio frequency. 3. A device according to claim 1 or 2, the device being used for collision warnings between at least a first unit and a second unit, characterized in that the simulation computer (7) of the first unit both simulates the position of the first unit in the coordinate system and in time to a first table and also simulates, as guided by communicated data on position and time of the second unit, the position of the second unit in the coordinate system in time to a second table, whereupon the simulation computer (7) compares the first table and the second table, and issues, for agreeing data on position and time, a warning signal.

Inventors: BERGLJUNG PETER, BERGSTROEM TOMMY, BERGLJUNG, PETER, BERGSTROEM, TOMMY
Applicants: BERGLJUNG PETER, BERGSTROEM TOMMY, SAAB DYNAMICS AB, BERGLJUNG, PETER, BERGSTROEM, TOMMY
Application year: 1997
Main classification: G09B9
IPC codes: F41G3, G08G5, G09B9