Helicopter ship board landing system

• US 20100228408A1
• Filed: 09/13/2006
• Published: 09/09/2010
• Est. Priority Date: 09/14/2005
• Status: Active Grant

• Current Assignee: Novatel Incorporated (Hexagon AB)
• Original Assignee: Novatel Incorporated (Hexagon AB)
• Inventors: Boloye, Michael, Ford, Tom
• Granted Patent: US 8,949,011 B2
• Time in Patent Office: Days
• US Class Current: 701/16
• CPC Class Codes: G01C 21/165 combined with non-inertial navigation instruments
• CPC Class Codes: G01C 21/28 with correlation of data from several navigational instruments
• CPC Class Codes: G01S 19/04 providing carrier phase data
• CPC Class Codes: G01S 19/15 Aircraft landing systems
• CPC Class Codes: G01S 19/26 involving a sensor measurement for aiding acquisition or tracking
• CPC Class Codes: G05D 1/0684 on a moving platform, e.g. aircraft carrier
• CPC Class Codes: G05D 1/0858 specially adapted for vertical take-off of aircraft
• CPC Class Codes: G05D 1/102 specially adapted for vertical take-off of aircraft
• CPC Class Codes: G08G 5/0013 with a ground station
• CPC Class Codes: G08G 5/025 Navigation or guidance aids radar or analogous systems specially adapted for landing purposes G01S13/913

Abstract

A system for maneuvering an aircraft for operations in connection with a sea-going vessel, the vessel having a designated area for landings and sling-load operations. Each of the aircraft has a navigation unit (INU) comprising a GPS receiver and an inertial navigation unit. The INU'"'"'s are updated by data from the GPS receivers and the data from the shipboard unit'"'"'s GPS receiver and INU are transmitted to the aircraft. The aircraft performs RTK calculations to determine a vector to the shipboard GPS antennas and modifies the vector with data from the INU'"'"'s.

Claims

1. A system for positioning an aircraft relative to a designated location on an ocean-going vessel, the system comprising:

A. a shipboard navigation unit comprising;

1. a first GPS antenna,

2. a first GPS receiver for processing signals from the first GPS antenna,

3. a first inertial navigation unit (INU),

the first INU configured to receive periodically updated data generated by said first GPS receiver, at a rate that minimizes INU error;

4. a transmitter for transmitting over a wireless link, shipboard GPS data and INU data;

B. an aircraft-based navigation unit comprising;

1. a second GPS antenna,

2. a second GPS receiver for processing signals received from the second GPS antenna,

3. a second INU,

the second INU configured to receive periodically updated data generated by the second GPS receiver, both said first INU and said second INU being updated with its respective GPS data, the timing for generating such updates is such as to cause the updates to have the same time tag,

4. a receiver for receiving signals from said shipboard navigation unit, said signals being transmitted over the link by the transmitter,

5. an RTK arrangement configured to generate at the aircraft an RTK moving baseline vector from the first GPS antenna to the second GPS antenna, said RTK arrangement further configured for

differencing a post update remote position of the aircraft with a post update base station position of the vessel to obtain a second vector, and subtracting the resulting second vector from the RTK moving baseline vector to obtain a correction; and

6. the aircraft INU further configured to update its output with the correction and to compute a position vector of high accuracy from the aircraft INU to a designated location on the vessel, said designated location being a landing pad.

2. The system defined in claim 1 including said RTK arrangement is further configured for generating a second vector from the first GPS antenna to the designated location and transmitting the data for generating said second vector to the aircraft which generates a position vector from the aircraft to the the landing pad.

3. The system defined in claim 1 in which:

A. the second GPS receiver provides its outputs at periodic intervals; and

B. the second INU updates the output of the second inertial unit in response to the outputs of the second GPS receiver.

4. The system defined in claim 3 including a Kalman filter that updates the parameters of the second inertial unit.

6. The system of claim 1 wherein said RTK arrangement is configured to enhance position data provided by said second GPS receiver to create further enhanced position data and to calculate an RTK vector from the aircraft to the shipboard, first GPS antenna.

7. The system of claim 6 further comprising a computer in said aircraft navigation unit that is configured to update the inertial navigation unit periodically with said further enhanced position data, to create an output position of the aircraft.

8. The system of claim 7 wherein said update position is calculated using a Kalman filter.

9. The system of claim 7 wherein the output position of the inertial system in the aircraft is modified by a post-update position correction to restore relative accuracy between the shipboard system and the aircraft system.

10. The system of claim 9 wherein said correction is computed by differencing a post-update position of the vessel and a post-update position of the aircraft, and subtracting this difference from said RTK vector used to generate a pre-update position of the aircraft.

11. The system of claim 1 wherein an updated aircraft position includes a vector between the vessel and the aircraft that is calculated using actual measurements occurring at substantially the same time from the second receiver and the first receiver, respectively.

12. The system of claim 11 wherein said updated aircraft position is used to update a Kalman filter in the aircraft navigation system to determine an accurate aircraft position, said aircraft position being adjusted to accommodate latency in the calculated measurements.

13. The system of claim 12 wherein the timing used to generate said updated aircraft position is adapted to ensure said measurements have the same time tag.

14. The system of claim 1 wherein RTK corrections to a GPS position of the aircraft provide the aircraft with an accurate position relative to said first GPS antenna onboard said vessel.

15. The system of claim 1 wherein a computer on the aircraft is configured to compare inertial navigation unit position data on the aircraft to inertial navigation unit position data transmitted to the aircraft from the vessel, to determine a low latency distance from and bearing to the GPS antenna on board said vessel from the aircraft.

16. The system of claim 1 wherein said navigation system on board said vessel is further configured to calculate information including parameters of a vector from the first GPS antenna to a landing pad.

17. The system of claim 16 wherein said information is transmitted over said wireless link from the vessel to the aircraft.

18. The system of claim 17 wherein the aircraft uses said information to provide the aircraft with a vector to a landing pad on the vessel.

5. (canceled)

19. A system for positioning an aircraft relative to a designated location on an ocean-going vessel, the system comprising:

A. on the vessel, a navigation unit including;

1. a first GPS receiver configured to receive and process signals received over a first GPS antenna, thereby to provide periodic position data;

2. a first inertial navigation unit (INU) configured to received periodically updated data generated by said first GPS receiver at a rate that minimizes INU error, relating to the position of the vessel;

3. a transmitter that transmits over a wireless link to an associated aircraft, the position data generated by the first GPS receiver and the first INU; and

B. in the aircraft, a navigation unit including;

1. a second GPS receiver configured for receiving and processing GPS signals received over a second GPS antenna,

2. a second INU having an output that is updated in accordance with the data generated by the second GPS receiver, both said first INU and said second INU being updated with its respective GPS data, and the timing for generating such updates is at the even second mark,

3. a receiver adapted to receive signals transmitted over a wireless link by the transmitter in the navigation unit on the vessel,

4. an RTK arrangement configured to process the GPS data to generate an RTK moving baseline vector from the second antenna to the first antenna, and said RTK arrangement being further configured for differencing a post update remote position at the aircraft with a post update base station position on the ship and subtracting the resulting vector from the RTK moving baseline vector to obtain a correction, and

5. the aircraft INU being further configured to update its output with said correction and to compute a position vector of high accuracy to guide the aircraft for landing at the designated location on the vessel.

20. The system of claim 19 further comprising:

said navigation unit on said aircraft being further configured for comparing inertial navigation unit position data on the aircraft to inertial navigation unit position data transmitted to the aircraft from the vessel, to determine a low latency distance from and bearing to the GPS antenna on board said vessel from the aircraft.

21. The system of claim 19 wherein said aircraft comprises a helicopter.