Geodetic survey method

• US 4,060,718 A
• Filed: 12/10/1976
• Issued: 11/29/1977
• Est. Priority Date: 12/10/1976
• Status: Expired due to Term

• Current Assignee: Litton Systems Incorporated
• Original Assignee: Litton Systems Incorporated
• Inventors: Huddle, James R.
• Primary Examiner(s): Ruggiero, Joseph F.
• Application Number:
  US05/749,356
• Time in Patent Office: 354 Days
• Field of Search: 235/150.27, 235/150.26, 235/150.25, 235/150.2, 235/151.3, 235/181, 340/15.5 R, 340/15.5 DS, 340/15.5 DP, 340/15.5 SS, 340/15.5 VD, 340/15.5 TN, 340/24, 33/1 R, 33/1 H, 33/318, 33/320, 33/321, 33/322, 33/331, 250/253, 73/382, 346/33 C, 324/1
• US Class Current: 702/2
• CPC Class Codes: G01C 21/166 Mechanical, construction or arrangement details of inertial navigation systems
• CPC Class Codes: G01V 7/06 Analysis or interpretation of gravimetric records

Abstract

The present method involves the detection of variations of the direction of gravity from the mathematical model of the earth, which may be caused by the presence of a discontinuity in the earth'"'"'s surface, with relatively heavy materials in the earth'"'"'s crust causing a deflection of gravity toward such heavier material. In accordance with the present method an inertial system is mounted in a mobile vehicle and the vehicle is moved along a survey route from a first control point to a second control point, with the locations and the deflection from the vertical being known at the two control points. The vehicle is stopped periodically between the two control points in order to eliminate accumulate errors in the inertial system, and to record the position of intermediate points to the surveyed. At each of the stopping points the indicated position of the stopping points relative to latitude, longitude, and elevation are recorded, and additional inertial system parameters are recorded as required to determine the deflection of the vertical at each of the survey points. To avoid complex intermingling of errors associated with the inertial system with the change in the deflection of the vertical, the inertial platform is not releveled at each of the stopping points. When the vehicle reaches the second control point, the position indicated by the inertial guidance system is compared with the actual position of the second control point as to latitude, longitude, and elevation, and following the determination of errors, the position of the various intermediate stopping points are recalculated taking the overall error and the time at which each point was surveyed into consideration. Similarly, the error in the deflection of the vertical, which is separate from the error in position, is determined, and the deflection from the vertical of each of the intermediate survey points is then determined. The results of the survey may then be plotted on a map.

Claims

1. A geodetic survey method using an inertial surveying system mounted in a vehicle which may be periodically stopped or brought to a substantially fixed position relative to the earth, comprising the steps of:

calibrating the system while the vehicle is in a fixed position including biasing the inertial system platform gyros and aligning the system accelerometers with the local coordinates;

at a first control point having a known location and a known deflection of the vertical, recording the surveying system indicated position, and recording the output from the inertial system sensing units, as required for determining the deflection of the vertical;

moving the vehicle along the terrain to be surveyed;

stopping the vehicle, at points which are to be surveyed, and at time intervals not to exceed the survey limit time interval, and eliminating accumulated errors from said system;

at all stops recording position including latitude, longitude, elevation, and the output from inertial system sensing units as required for determining the deflection of vertical, without releveling the inertial platform;

proceeding to a control point having a known location and known deflection of the vertical to take a second control point indication reading, and recording the inertial surveying system indicated position with regard to latitude, longitude elevation, and recording the output from the inertial system sensing units as required for determining the deflection of the vertical;

determining the position errors in latitude, longitude and elevation between the first and second control point indication readings;

recalculating the position of the intermediate survey points, utilizing the position errors between the two control point readings;

determining the error in the deflection of the vertical between the first and second control point indication readings; and

calculating the deflection of the vertical at the intermediate survey points, utilizing the error in the change in the deflection of the vertical between the two control point readings.

2. A geodetic survey method as defined in claim 1 further including the step of leveling said inertial system to the local gravitational vertical at the first control point.

3. A geodetic survey method as defined in claim 1 further including the step of plotting the results of the survey on a map.

4. A geodetic survey method as defined in claim 1 including the additional step of recording the time of each stop, and wherein the recalculation of the location of the intermediate survey point locations, and the calculation of the deflection of the vertical of the intermediate survey points, utilize the times of surveying the intermediate points as inputs.

5. A geodetic survey method using an inertial surveying system mounted in a vehicle which may be periodically stopped or brought to a substantially fixed position relative to the earth, comprising the steps of:

initially calibrating and aligning the inertial surveying system while the vehicle is in a fixed position;

at a first control point having a known location and a known deflection of the vertical, recording the outputs from the inertial system including outputs required for determining the deflection of the vertical;

moving the vehicle along the terrain to be surveyed;

stopping the vehicle, at points which are to be surveyed, and at time intervals not to exceed the survey limit time interval, and eliminating accumulated errors from said system;

at all stops recording the outputs from the inertial system required for determining the deflection of vertical, without releveling the inertial platform;

proceeding to a control point having a known location and a known deflection of the vertical to take a second control point indication reading, and recording the outputs from the inertial system required for determining the deflection of the vertical;

determining the error in the deflection of the vertical between the first and second control point indication readings; and

calculating the deflection of the vertical at the intermediate survey points, utilizing the error in the deflection of the vertical between the two control point readings.

6. A geodetic survey method as defined in claim 5 further comprising the steps of:

determining the position errors between the first and second control point indication readings; and

calculating the position of the intermediate survey points, utilizing the position errors between the two control point readings.

7. A geodetic survey method as defined in claim 5 further including the steps of:

recording the time of each of the stops; and

calculating the deflection of the vertical at the survey points as a function of the time of stopping at each of said stops.