Method of Correcting the Orientation of a Freely Installed Accelerometer in a Vehicle

• US 20130081442A1
• Filed: 10/01/2012
• Published: 04/04/2013
• Est. Priority Date: 09/30/2011
• Status: Active Grant

• Current Assignee: Appy Risk Technologies Limited (Trak Global Group Ltd.)
• Original Assignee: Intelligent Mechatronic Systems Inc. (Trak Global Group Ltd.)
• Inventors: Basir, Otman A., Jamali, Seyed Hamidreza, Miners, William Ben, Toonstra, Jason
• Granted Patent: US 9,581,615 B2
• Time in Patent Office: Days
• US Class Current: 73/1.38
• CPC Class Codes: G01C 21/185 for gravity
• CPC Class Codes: G01C 25/00 Manufacturing, calibrating, cleaning, or repairing instruments or devices referred to in the other groups of this subclass testing, calibrating or compensating compasses G01C17/38
• CPC Class Codes: G01P 21/00 Testing or calibrating of apparatus or devices covered by the preceding groups
• CPC Class Codes: G01S 19/53 Determining attitude

Abstract

A vehicle monitoring system includes an accelerometer installed in the vehicle in an unknown orientation. The system infers the orientation of the accelerometer in the vehicle from the acceleration signals. The proposed method detects and corrects the orientation in two steps. In the first step, the gravity vector is used to estimate the orientation in the vertical plane. Then, based on the acceleration data collected during the vehicle movement, the heading of the vehicle is estimated and the orientation within the horizontal plane is corrected.

Claims

1. A method for orienting an accelerometer in in a vehicle including the steps of:

a) determining a gravity vector relative to the accelerometer orientation; and

b) determining a forward direction of the vehicle to determine the horizontal orientation of the accelerometer relative to the vehicle.

2. The method of claim 1 wherein said step b) is based upon a determination that change in direction of acceleration in a plane orthogonal to the gravity vector is below a threshold.

3. The method of claim 1 wherein said step b) is based upon a determination that the vehicle is traveling forward based upon speed information from the vehicle.

4. The method of claim 1 further including:

using a previous determination of horizontal orientation from a previous trip as an initial accelerometer orientation relative to the vehicle.