Real-time IMU signal emulation method for test of Guidance Navigation and Control systems

• US 6,298,318 B1
• Filed: 07/01/1998
• Issued: 10/02/2001
• Est. Priority Date: 07/01/1998
• Status: Expired due to Term

• Current Assignee: American GNC Corporation
• Original Assignee: Ching-Fang Lin
• Inventors: Lin, Ching-Fang
• Primary Examiner(s): Teska, Kevin J.
• Assistant Examiner(s): THOMSON, WILLIAM D
• Application Number:
  US09/108,595
• Time in Patent Office: 1,189 Days
• Field of Search: 703/13, 703/20, 703/21, 703/22, 703/24, 703/6, 703/23, 434/30, 434/35, 434/2
• US Class Current: 703/23
• CPC Class Codes: G01C 21/16 by integrating acceleration or speed, i.e. inertial navigation
• CPC Class Codes: G01C 25/005 initial alignment, calibration or starting-up of inertial devices

Abstract

A real-time IMU emulation method for GNC method includes the step of receiving real-time flight data from a 6DOF flight simulator and generating simulated IMU electronic signals according to the IMU measurement modules and error modules defined by the user, and injecting said simulated IMU electronic signals into an on-board GNC system which causes the on-board GNC system into “thinking” that the vehicle is really moving. The on-board GNC system which is installed on the vehicle is motionless during the emulation test, so that 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. 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.

Claims

1. A real-time IMU emulation method for GNC system, comprising the steps of:

(a) inputting IMU measurement modules and IMU error modules into a real-time IMU emulation system according to a real IMU device of an on-board GNC system to be tested, wherein said IMU measurement modules comprises Gyro measurement model and accelerometer measurement model which are determined by inertial sensor principles, and that said IMU error modules comprises Gyro error module and accelerometer error module which are defined by a user according to an actual IMU used in said on-board GNC system to be tested;

(b) producing real-time trajectory data from a 6DOF trajectory generator and sending said real-time trajectory data to said real-time IMU emulation system, wherein said real-time trajectory data are defined by said user and said real-time IMU emulation system produces IMU signals as if a vehicle is really transporting along a trajectory defined by said user;

(c) generating output data that are real-time IMU data identical to said real IMU device in a designated mission by said IMU model of said real-time IMU emulation system, wherein said real-time IMU data are determined by said 6DOF trajectory data, said IMU measurement modules, and said IMU error modules;

(d) converting said real-time IMU data into Simulated IMU electronic signals by an IMU signal generator in a simulator of said real-time IMU emulation system, wherein said IMU signal generator is an interface board in said emulation computer for producing said Simulated IMU electronic signals which are identical to that produced by said real IMU in said on-board GNC system;

(e) processing said generated Simulated IMU electronic signals by a regulator and connector circuit to form suitable electrical specifications and connector pin arrangement that is compatible to a GNC/IMU interface; and

(f) injecting said electronic signals into said on-board GNC system to excite said on-board GNC system, wherein with said dynamic 6DOF trajectory and compatible electronic signals, said real-time IMU emulation system provides same IMU signals as a real IMU on a transporting carrier, and that when said on-board GNC system is excited in dynamic operation, a performance thereof is able to be tested and evaluated as if carrying out a real transportation test.

2. A real-time IMU emulation method for On-board GNC system, as recited in claim 1, after the above step (f), further comprising an additional step of collecting test data from said on-board GNC system by a computer system connected between said 6DOF trajectory generator and said on-board GNC system, so as to compare said real-time trajectory data from said 6DOF trajectory generator with a GNC resolved vehicle trajectory data output from said on-board GNC system in order to determine if said on-board GNC system works properly and to evaluate its performance.

3. A real-time IMU emulation system, as recited in claim 2, wherein said IMU measurement modules and error modules are a group of software programs used to produce IMU data according to said input trajectory data and defined IMU error parameters by the user, wherein said Gyro measurement module and said accelerometer measurement module which are based on Gyro and accelerometer mathematical modules respectively, and said Gyro error module and said accelerometer error module are based on Gyro and accelerometer error modules respectively, wherein said gyro and accelerometer measurement modules describe a relationship between a motion of said GNC avionics on-board vehicle and outputs of sensors used in said on-board GNC system to be tested, and that said Gyro and accelerometer error modules describe the performance of said sensors.

4. A real-time IMU emulation system, which is connected between a GNC avionics on-board vehicle for bypassing a real IMU in an on-board GNC system of said vehicle and a 6DOF trajectory generator for producing a real-time trajectory data to send to said real-time IMU emulation system, comprising:

an IMU emulation computer which is a computation platform for said real-time IMU emulation system, to which a plurality of off-the-shelf open standard bus modules, including IMU measurement modules and IMU error modules, are defined by a user and input according to said real IMU of said GNC system, wherein said IMU measurement modules include Gyro measurement module and accelerometer measurement module and said IMU error modules include Gyro error module and accelerometer error module, wherein said real-time trajectory data are sent to said IMU emulation computer which generates real-time IMU data;

an IMU signal generator, which is installed between said IMU emulation computer and said on-board GNC system to be tested, for converting said real-time IMU data into simulated IMU electronic signals which are able to be injected into said on-board GNC system and are identical to said real IMU in said on-board GNC system of said vehicle during a designated mission and are determined by said real-time trajectory data, said IMU measurement modules and said IMU error modules;

a regulator and connector circuit for processing said Simulated IMU electronic signals to form corresponding electrical specifications and connector pin arrangement, wherein said simulated IMU electronic signals are injected into said on-board GNC system to excite said on-board GNC system, thereby with said dynamic trajectory signals and said compatible simulated IMU electronic signals, said real-time IMU emulation system provides same IMU signals as a real IMU on a transporting carrier, so that the performance of said on-board GNC system is able to be tested and evaluated as if said on-board GNC system is carrying out a real transportation test when said on-board GNC system is excited in dynamic operation.

5. A real-time IMU emulation system, as recited in claim 4, wherein said IMU measurement modules and error modules are a group of software programs used to produce IMU data according to said input trajectory data and defined IMU error parameters by the user, wherein said Gyro measurement module and said accelerometer measurement module which are based on Gyro and accelerometer mathematical modules respectively, and said Gyro error module and said accelerometer error module are based on Gyro and accelerometer error modules respectively, wherein said gyro and accelerometer measurement modules describe a relationship between a motion of said GNC avionics on-board vehicle and outputs of sensors used in said on-board GNC system to be tested, and that said Gyro and accelerometer error modules describe the performance of said sensors.

6. A real-time IMU emulation system, as recited in claim 4, wherein said IMU electronic signal generator includes an analog signal interface which is a multi-channel D/A converter circuit board for generating analog IMU signals, which comprises a bus interface circuitry, a DMA interface and an interrupt interface respectively connected to a standard bus of said IMU emulation computer, said analog signal interface further comprising a FIFO circuitry connected with said bus interface circuitry, a multi-channel D/A converter circuitry connected between said FIFO circuitry and an analog signal regulator and/or isolator of said signal regulator and connector board, and a timing circuitry connected between said DMA interface and said multi-channel D/A converter circuitry.

7. A real-time IMU emulation system, as recited in claim 5, wherein said IMU electronic signal generator includes an analog signal interface which is a multi-channel D/A converter circuit board for generating analog IMU signals, which comprises a bus interface circuitry, a DMA interface and an interrupt interface respectively connected to a standard bus of said IMU emulation computer, said analog signal interface further comprising a FIFO circuitry connected with said bus interface circuitry, a multi-channel D/A converter circuitry connected between said FIFO circuitry and an analog signal regulator and/or isolator of said signal regulator and connector board, and a timing circuitry connected between said DMA interface and said multi-channel D/A converter circuitry.

8. A real-time IMU emulation system, as recited in claim 4, wherein said IMU electronic signal generator includes a serial signal interface which is a communication control circuit board for generating serial IMU signals, which comprises a bus interface circuitry connected with said standard bus of said IMU emulation computer, an interrupt interface connected between said bus interface circuitry and said standard bus of said IMU emulation computer, a discrete logic circuitry connected between said bus interface circuitry and a serial signal regulator and connector of said signal regulator and connector board, and an interface circuitry connected between said bus interface circuitry and said signal regulator and connector of said signal regulator and connector board.

9. A real-time IMU emulation system, as recited in claim 5, wherein said IMU electronic signal generator includes a serial signal interface which is a communication control circuit board for generating serial IMU signals, which comprises a bus interface circuitry connected with said standard bus of said IMU emulation computer, an interrupt interface connected between said bus interface circuitry and said standard bus of said IMU emulation computer, a discrete logic circuitry connected between said bus interface circuitry and a serial signal regulator and connector of said signal regulator and connector board, and an interface circuitry connected between said bus interface circuitry and said signal regulator and connector of said signal regulator and connector board.

10. A real-time IMU emulation system, as recited in claim 6, wherein said IMU electronic signal generator further includes a serial signal interface which is a communication control circuit board for generating serial IMU signals, which comprises a bus interface circuitry connected with said standard bus of said IMU emulation computer, an interrupt interface connected between said bus interface circuitry and said standard bus of said IMU emulation computer, a discrete logic circuitry connected between said bus interface circuitry and a serial signal regulator and connector of said signal regulator and connector board, and an interface circuitry connected between said bus interface circuitry and said signal regulator and connector of said signal regulator and connector board.

11. A real-time IMU emulation system, as recited in claim 7, wherein said IMU electronic signal generator further includes a serial signal interface which is a communication control circuit board for generating serial IMU signals, which comprises a bus interface circuitry connected with said standard bus of said IMU emulation computer, an interrupt interface connected between said bus interface circuitry and said standard bus of said IMU emulation computer, a discrete logic circuitry connected between said bus interface circuitry and a serial signal regulator and connector of said signal regulator and connector board, and an interface circuitry connected between said bus interface circuitry and said signal regulator and connector of said signal regulator and connector board.

12. A real-time IMU emulation system, as recited in claim 4, wherein said IMU electronic signal generator includes a pulse signal interface which is a multi-channel digital controlled frequency generator circuit board for producing pulse IMU signals, which comprises bus interface circuitry connected with said standard bus of said IMU emulation computer, an interrupt interface connected between said bus interface circuitry and said standard bus of said IMU emulation computer, a multi-channel digital to frequency convert circuitry connected with said bust interface circuitry, and a Inc/Dec pulse separation circuitry connected between said multi-channel digital to frequency convert circuitry and a pulse signal regulator and connector of said signal regulator and connector board.

13. A real-time IMU emulation system, as recited in claim 5, wherein said IMU electronic signal generator includes a pulse signal interface which is a multi-channel digital controlled frequency generator circuit board for producing pulse IMU signals, which comprises bus interface circuitry connected with said standard bus of said IMU emulation computer, an interrupt interface connected between said bus interface circuitry and said standard bus of said IMU emulation computer, a multi-channel digital to frequency convert circuitry connected with said bust interface circuitry, and a Inc/Dec pulse separation circuitry connected between said multi-channel digital to frequency convert circuitry and a pulse signal regulator and connector of said signal regulator and connector board.

14. A real-time IMU emulation system, as recited in claim 10, wherein said IMU electronic signal generator further includes a pulse signal interface which is a multi-channel digital controlled frequency generator circuit board for producing pulse IMU signals, which comprises bus interface circuitry connected with said standard bus of said IMU emulation computer, an interrupt interface connected between said bus interface circuitry and said standard bus of said IMU emulation computer, a multi-channel digital to frequency convert circuitry connected with said bust interface circuitry, and a Inc/Dec pulse separation circuitry connected between said multi-channel digital to frequency convert circuitry and a pulse signal regulator and connector of said signal regulator and connector board.

15. A real-time IMU emulation system, as recited in claim 11, wherein said IMU electronic signal generator includes a pulse signal interface which is a multi-channel digital controlled frequency generator circuit board for producing pulse IMU signals, which comprises bus interface circuitry connected with said standard bus of said IMU emulation computer, an interrupt interface connected between said bus interface circuitry and said standard bus of said IMU emulation computer, a multi-channel digital to frequency convert circuitry connected with said bust interface circuitry, and a Inc/Dec pulse separation circuitry connected between said multi-channel digital to frequency convert circuitry and a pulse signal regulator and connector of said signal regulator and connector board.

16. A real-time IMU emulation system, as recited in claim 4, wherein said IMU electronic signal generator includes a parallel digital signal interface which comprises two sets of interrupt interfaces and bus interface circuitries, wherein said first set of said interrupt interface and bus interface circuitry are mutual connected and respectively connected to said standard bus of IMU emulation computer, and said second set of said interrupt interface and bus interface circuitry are also mutual connected and respectively connected to a standard bus of said navigation (INS) computer of said on-board GNC system, and that said first bus interface circuitry is connected to said second bus interface circuitry.

17. A real-time IMU emulation system, as recited in claim 5, wherein said IMU electronic signal generator includes a parallel digital signal interface which comprises two sets of interrupt interfaces and bus interface circuitries, wherein said first set of said interrupt interface and bus interface circuitry are mutual connected and respectively connected to said standard bus of IMU emulation computer, and said second set of said interrupt interface and bus interface circuitry are also mutual connected and respectively connected to a standard bus of said navigation (INS) computer of said on-board GNC system, and that said first bus interface circuitry is connected to said second bus interface circuitry.

18. A real-time IMU emulation system, as recited in claim 14, wherein said IMU electronic signal generator further includes a parallel digital signal interface which comprises two sets of interrupt interfaces and bus interface circuitries, wherein said first set of said interrupt interface and bus interface circuitry are mutual connected and respectively connected to said standard bus of IMU emulation computer, and said second set of said interrupt interface and bus interface circuitry are also mutual connected and respectively connected to a standard bus of said navigation (INS) computer of said on-board GNC system, and that said first bus interface circuitry is connected to said second bus interface circuitry.

19. A real-time IMU emulation system, as recited in claim 15, wherein said IMU electronic signal generator further includes a parallel digital signal interface which comprises two sets of interrupt interfaces and bus interface circuitries wherein said first set of said interrupt interface and bus interface circuitry are mutual connected and respectively connected to said standard bus of IMU emulation computer, and said second set of said interrupt interface and bus interface circuitry are also mutual connected and respectively connected to a standard bus of said navigation (INS) computer of said on-board GNC system, and that said first bus interface circuitry is connected to said second bus interface circuitry.

20. A real-time IMU emulation system, as recited in claim 4, further comprising an Ethernet network controller board for receiving said real-time trajectory data from said 6DOF trajectory generator, wherein said 6DOF trajectory generator and said real-time IMU emulation system are connected by a serial communication port.

21. A real-time IMU emulation system, as recited in claim 5, further comprising an Ethernet network controller board for receiving said real-time trajectory data from said 6DOF trajectory generator, wherein said 6DOF trajectory generator and said real-time IMU emulation system are connected by a serial communication port.

22. A real-time IMU emulation system, as recited in claim 6, further comprising an Ethernet network controller board for receiving said real-time trajectory data from said 6DOF trajectory generator, wherein said 6DOF trajectory generator and said real-time IMU emulation system are connected by a serial communication port.

23. A real-time IMU emulation system, as recited in claim 7, further comprising an Ethernet network controller board for receiving said real-time trajectory data from said 6DOF trajectory generator, wherein said 6DOF trajectory generator and said real-time IMU emulation system are connected by a serial communication port.

24. A real-time IMU emulation system, as recited in claim 10, further comprising an Ethernet network controller board for receiving said real-time trajectory data from said 6DOF trajectory generator, wherein said 6DOF trajectory generator and said real-time IMU emulation system are connected by a serial communication port.

25. A real-time IMU emulation system, as recited in claim 11, further comprising an Ethernet network controller board for receiving said real-time trajectory data from said 6DOF trajectory generator, wherein said 6DOF trajectory generator and said real-time IMU emulation system are connected by a serial communication port.

26. A real-time IMU emulation system, as recited in claim 14, further comprising an Ethernet network controller board for receiving said real-time trajectory data from said 6DOF trajectory generator, wherein said 6DOF trajectory generator and said real-time IMU emulation system are connected by a serial communication port.

27. A real-time IMU emulation system, as recited in claim 15, further comprising an Ethernet network controller board for receiving said real-time trajectory data from said 6DOF trajectory generator, wherein said 6DOF trajectory generator and said real-time IMU emulation system are connected by a serial communication port.

28. A real-time IMU emulation system, as recited in claim 18, further comprising an Ethernet network controller board for receiving said real-time trajectory data from said 6DOF trajectory generator, wherein said 6DOF trajectory generator and said real-time IMU emulation system are connected by a serial communication port.

29. A real-time IMU emulation system, as recited in claim 19, further comprising an Ethernet network controller board for receiving said real-time trajectory data from said 6DOF trajectory generator, wherein said 6DOF trajectory generator and said real-time IMU emulation system are connected by a serial communication port.

30. A real-time IMU emulation system, as recited in claim 4, further comprising a test analysis system which is further independently connected between said 6DOF trajectory generator and said on-board GNC system, wherein a reference trajectory is sent to said test analysis system which is compared with on-board system solutions.

31. A real-time IMU emulation system, as recited in claim 5, further comprising a test analysis system which is further independently connected between said 6DOF trajectory generator and said on-board GNC system, wherein a reference trajectory is sent to said test analysis system which is compared with on-board system solutions.

32. A real-time IMU emulation system, as recited in claim 6, further comprising a test analysis system which is further independently connected between said 6DOF trajectory generator and said on-board GNC system, wherein a reference trajectory is sent to said test analysis system which is compared with on-board system solutions.

33. A real-time IMU emulation system, as recited in claim 7, further comprising a test analysis system which is further independently connected between said 6DOF trajectory generator and said on-board GNC system, wherein a reference trajectory is sent to said test analysis system which is compared with on-board system solutions.

34. A real-time IMU emulation system, as recited in claim 10, further comprising a test analysis system which is further independently connected between said 6DOF trajectory generator and said on-board GNC system, wherein a reference trajectory is sent to said test analysis system which is compared with on-board system solutions.

35. A real-time IMU emulation system, as recited in claim 11, further comprising a test analysis system which is further independently connected between said 6DOF trajectory generator and said on-board GNC system, wherein a reference trajectory is sent to said test analysis system which is compared with on-board system solutions.

36. A real-time IMU emulation system, as recited in claim 14, further comprising a test analysis system which is further independently connected between said 6DOF trajectory generator and said on-board GNC system, wherein a reference trajectory is sent to said test analysis system which is compared with on-board system solutions.

37. A real-time IMU emulation system, as recited in claim 15, further comprising a test analysis system which is further independently connected between said 6DOF trajectory generator and said on-board GNC system, wherein a reference trajectory is sent to said test analysis system which is compared with on-board system solutions.

38. A real-time IMU emulation system, as recited in claim 18, further comprising a test analysis system which is further independently connected between said 6DOF trajectory generator and said on-board GNC system, wherein a reference trajectory is sent to said test analysis system which is compared with on-board system solutions.

39. A real-time IMU emulation system, as recited in claim 19, further comprising a test analysis system which is further independently connected between said 6DOF trajectory generator and said on-board GNC system, wherein a reference trajectory is sent to said test analysis system which is compared with on-board system solutions.