Data processing: structural design – modeling – simulation – and em – Emulation
Reexamination Certificate
1998-07-01
2001-10-02
Teska, Kevin J. (Department: 2123)
Data processing: structural design, modeling, simulation, and em
Emulation
C703S021000, C703S013000, C703S024000, C434S030000, C434S002000
Reexamination Certificate
active
06298318
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to IMU emulation, and more particularly to a real-time emulation method for ground test or hardware-in-the-loop test of GNC system, which allows unlimited dynamic 6DOF trajectory simulation of IMU for performing accurate test for the GNC system.
BACKGROUND OF THE PRESENT INVENTION
There are commonly unsolved difficult problems in the ground tests and laboratory hardware-in-the-loop tests of the inertial and integrated Guidance, Navigation, and Control (GNC) system on-board a military missile or a vehicle such as aircraft, spacecraft, ship, and car.
In the ground test, since the vehicle is stationary, the IMU in the GNC system can not produce dynamic electronic signals for it is a self-contained device. In other words, it is unable to test the accuracy and errors of the GNC system installed on-board vehicle while it is stationary. If the IMU and the GNC system are installed on-board a ground vehicle such as a car or a combat tank, the tester can still process a motion test for the IMU by actually driving the ground vehicle in relatively low cost. However, if the vehicle to be test is an aircraft or even a spacecraft, the cost and labors for actual-fly test are ultimately expensive.
In order to verify the correctness and/or evaluate the performance of an integrated GPS/INS system on the ground, before a real flight test or in the laboratory, the GPS/INS system must be excited by its dynamic sensor signals, as if the GPS/INS system were under an actual dynamic flight condition. Motion table approaches can put the GPS/INS system into actual motion and provide dynamic excitation to the system. But these approaches are usually costly, inconvenient, and even inaccurate.
A straightforward method for dynamic ground testing is the application of the flight motion tables that provide the motion of the vehicle during emulated flight in an installed system environment. With this method, the GPS receiver receives actual satellite RF signals and the IMU produces dynamic inertial measurement signals itself, for the integrated system is actually in motion. But this test method is not a viable solution. It needs a large set of testing equipment, its operational cost is high, its dynamic motion is limited, and its data acquisition during the emulation is not convenient. In fact, the motion table method is very much limited in the dynamic trajectory emulation. The rate table can only produce angular motion in one axis and it can not produce transnational motion. The centrifuge can only produce one or two direction acceleration and one angular rate and the motion of the IMU system is limited to a small space.
SUMMARY OF THE PRESENT INVENTION
Therefore the real-time computer emulation method for dynamic ground testing is desired.
It is thus a first object of the present invention to provide a real-time IMU emulation method in which the installed system on the vehicle is motionless during the emulation test, so the testing can be carried out in a laboratory or in an anechoic chamber facility and the IMU emulation can achieve the easy, effective, and least intrusive injection of emulated IMU signals into the INS computer.
A further object of the present invention is to provide a real-time IMU emulation method that generates IMU signals on the ground, under static conditions, identical to what would be encountered if the vehicle were flying. The present invention has features supporting the final integration of a developmental Guidance, Navigation, or Control (GNC) system installed into a vehicle. It assures testers that GNC avionics on-board vehicle work properly before and during a flight test. It also helps to debug on-board GNC avionics and verify system performance.
Another object of the present invention is to provide a real-time IMU emulation method, which receives real-time flight data from the 6DOF flight simulator and generates IMU electronic signals according to the IMU measurement modules and error modules defined by the user. The emulated electronic signals are injected into the installed avionics system, which causes the on-board GNC system computer into “thinking” that the vehicle is really moving.
Another object of the present invention is to provide a real-time IMU emulation method which allows unlimited dynamic 6DOF trajectory simulation because the motion devices are removed from the test system. Only with the IMU emulation method and the corresponding system can the tester be able to test the GNC system performance over a real mission trajectory.
Another object of the present invention is to provide a real-time IMU emulation method that is efficiently utilized for ground test of installed systems, laboratory hard-in-the-loop dynamic simulation, and GNC system analysis and development.
Another object of the present invention is to provide a real-time IMU emulation method that can perform accurate test for the GNC system. In the simulated test, the reference trajectory is accurate and known, since it is defined by the tester, so that the high accuracy of the simulated method is very useful for the performance verification of the GNC system.
Another object of the present invention is to provide a real-time IMU emulation method adapted to predict and evaluate the dynamic GNC performance through a simulated test, which can make the follow on real flight test safer and will greatly reduce the number of the real flight test. Consequently, the operation and test cost of the simulated method is low for it does not need the expensive motion device in the test system. The maintenance of the test system is simplified.
Another object of the present invention is to provide a real-time IMU emulation method which includes the steps of emulating the behavior of a real IMU as defined by the user, producing dynamic electronic IMU signals and injecting these signals into the integration system to be tested, and bypassing the real IMU in the tested system since the IMU can not produce dynamic signals when the system is stationary because of its self-contained characteristics
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Chan Raymond Y.
David and Raymond Patent Group
Teska Kevin J.
Thomson William
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