Cross track strapdown inertial quidance system

• US 3,924,824 A
• Filed: 10/17/1973
• Issued: 12/09/1975
• Est. Priority Date: 10/17/1973
• Status: Expired due to Term

• Current Assignee: Edwin G. Solov, Peter M. Brodie
• Original Assignee: Edwin G. Solov, Peter M. Brodie
• Inventors: Brodie, Peter M., Solov, Edwin G.
• Primary Examiner(s): Bentley, Stephen C.
• Assistant Examiner(s): Jordan, C. T.
• Application Number:
  US05/407,121
• Time in Patent Office: 783 Days
• Field of Search: 244/3.15,3.2
• US Class Current: 244/3.2
• CPC Class Codes: F41G 7/36 using inertial references
• CPC Class Codes: F42B 15/01 Arrangements thereon for guidance or control steering arrangements F42B10/60; aircraft flight control B64C; guidance systems other than those installed aboard F41G7/00, F41G9/00; locating by use of radio or other waves G01S; flight control in general G05D1/00; computer aspects G06]

Abstract

A simplified strapdown inertial guidance system is provided for the cross track or inertial '"'"''"'"''"'"''"'"'line-of-sight'"'"''"'"''"'"''"'"' planar guidance of an unmanned tactical vehicle, or the like; wherein one of the attitude angles can be of large magnitude. The system includes three orthogonally-mounted accelerometers and two gyroscopes. The large attitude angle is accommodated by torquing the appropriate gyroscope in a capture loop. The system implements the body attitude angles to inertial attitude angles in two steps. First a transformation is made from body to gyroscope coordinates, and then a transformation is made from gyroscope to inertial coordinates.

Claims

1. A strapdown inertial guidance system for a vehicle, comprising:

a first accelerometer mounted in said vehicle for producing an output signal (AX) representing the acceleration of said vehicle along a heading axis;

a second accelerometer mounted in said vehicle for producing an output signal (Ay) representing the acceleration of said vehicle along a cross-heading axis perpendicular to said heading axis;

a third accelerometer mounted in said vehicle for producing an output signal (AZ) representing the acceleration of said vehicle along a Z-axis perpendicular to said heading and crossheading axes;

roll axis gyroscope means captured loosely about null mounted on said vehicle to produce output signals representing the pitch angle ( theta ) and the rate of angular rotation ( Eta ) about the roll axis of the vehicle; and

pitch axis gyroscope means mounted on said vehicle to produce output signals representative of the yaw angle ( Psi ) and of the roll angle ( phi ) of the vehicle.

2. The inertial guidance system defined in claim 1, and which includes a first transformation matrix coupled to said gyroscopes and to said accelerometers, and responsive to the output signals therefrom representative of the roll, yaw and pitch angles, to transform the coordinate frame of said accelerometer signals from a body coordinate frame to an inertial coordinate frame.

3. The inertial guidance system defined in claim 2, and which includes a second transformation matrix coupled to said first transformation matrix to transform the accelerometer signals from said first matrix from a moving gyroscope coordinate frame to an inertial coordinate frame.

4. The inertial guidance system defined in claim 3, and which includes computation means coupled to said roll axis gyroscope and responsive to the output signal therefrom representing the rate of angular rotation about the pitch axis, signals representative of the sin and cosine of the pitch angle and for introducing such signals to said second transformation matrix.

5. The inertial guidance system defined in claim 1, in which said roll axis gyroscope means is captured by bang-bang torquing about its null utilizing a hysteresis circuit.