METHOD AND MEANS FOR TRANSFORMING THE ACCELERATION SIGNALS GENERATED BY ACCELEROMETERS IN A FIRST COORDINATE SYSTEM INTO ACCELERATION SIGNALS IN A SECOND COORDINATE SYSTEM

• US 3,597,598 A
• Filed: 12/14/1964
• Issued: 08/03/1971
• Est. Priority Date: 12/14/1964
• Status: Expired due to Term

• Current Assignee: Donald F. Mcallister, Frank M. Pelteson
• Original Assignee: Donald F. Mcallister, Frank M. Pelteson
• Inventors: Mcallister, Donald F., Pelteson, Frank M.
• Application Number:
  US04/417,905
• Time in Patent Office: 2,423 Days
• US Class Current: 701/511
• CPC Class Codes: G01C 21/166 Mechanical, construction or arrangement details of inertial navigation systems
• CPC Class Codes: G01C 21/188 for accumulated errors, e.g. by coupling inertial systems with absolute positioning systems
• CPC Class Codes: G06G 7/22 for evaluating trigonometric functions; for conversion of co-ordinates; for computations involving vector quantities trigonometric computations using simultaneous equations G06G7/34 for computations in the complex plane; G06G7/20, G06G7/28 take precedence
• CPC Class Codes: Y10T 74/1221 Multiple gyroscopes

Abstract

A method and means for transforming the acceleration signals generated by orthogonally disposed accelerometers mounted upon an untorqued inertial gyro platform into acceleration signals which are useful in another coordinate system, for example, an earth base latitude and longitude coordinate system.

Claims

1. A method for converting the outputs from three accelerometers, each aligned to one axis of a Cartesian coordinate system fixed to a freely rotating platform into accelerometer outputs in a horizontal earth rotating coordinate system, comprising the steps of:

determining the constant direction cosine matrix c which transforms a first space-fixed coordinate system to a second space-fixed coordinate system by computing c from the following matrix equation;

2. Apparatus for calculating the fixed direction cosine matrix for converting first coordinate system accelerometer output signals of a freely rotating platform to accelerometer output signals in a second coordinate system comprising in combination:

means for releasing said platform to freely rotate from a preferred starting position;

means for determining the first coordinate space-fixed accelerometer outputs A'"'"''"'"'x, A'"'"''"'"'y and A'"'"''"'"'z from the following matrix;

3. Apparatus for converting the outputs from three accelerometers, each aligned to one axis of a Cartesian coordinate system fixed to a freely rotating platform into accelerometer outputs in a horizontal earth rotating coordinate system, comprising in combination:

means for releasing said platform to freely rotate from a preferred starting position;

means for determining the constant direction cosine matrix c by calculating c from the following matrix equation;

4. Apparatus for converting the output signals from three accelerometers mounted on a freely rotating platform into accelerometer output signals in a space-fixed coordinate system, comprising in combination:

means for transforming platform rotating accelerometer input signals in a first coordinate system into acceleration output signals in the second coordinate system, said means for transforming determining the acceleration output signals in the second coordinate system in response to the platform rotating accelerometer output signals in accordance with the relationship;