Distance factor learning device, distance factor learning method and current position calculating device

• US 10,001,566 B2
• Filed: 07/02/2014
• Issued: 06/19/2018
• Est. Priority Date: 11/29/2013
• Status: Active Grant

• Current Assignee: Clarion Co., Ltd. (Faurecia SA)
• Original Assignee: Clarion Co., Ltd. (Faurecia SA)
• Inventors: Liu, Zhixing, Kawabata, Akihiro
• Primary Examiner(s): Khatib, Rami
• Application Number:
  US15/100,102
• Publication Number:
  US 20170038474A1
• Time in Patent Office: 1,448 Days
• Field of Search: None
• CPC Class Codes: G01C 21/165 combined with non-inertial navigation instruments
• CPC Class Codes: G01C 22/00 Measuring distance traversed on the ground by vehicles, persons, animals or other moving solid bodies, e.g. using odometers, using pedometers
• CPC Class Codes: G01S 19/428 using multipath or indirect path propagation signals in position determination

Abstract

A distance factor learning device includes: a first learner that updates a first estimated value for the distance factor and a first parameter, based upon a measurement quantity, which is calculated based upon the vehicle speed pulses and the GPS information, the first estimated value for the distance factor and the first parameter; a second learner that updates a second estimate a value for the distance factor and a second parameter, based upon the measurement quantity, which is calculated based upon the vehicle speed pulses and the GPS information, the second estimated value for the distance factor and the second parameter; a difference calculation unit that calculates a difference between the first estimated value and the second estimated value; and an arithmetic operation control unit that overwrites the first parameter and the first estimated value at the first learner with the second parameter and the second estimated value at the second learner when the difference between the first estimated value and the second estimated value, having been calculated, is equal to or greater than a predetermined value.

Claims

1. A distance factor learning device that calculates an estimated value for a distance factor based upon a distance between a plurality of current positions obtained from GPS information, a number of vehicle speed pulses obtained while the distance is traveled, and a parameter which is an error index of the estimated value for the distance factor, and that is used for a current position calculation device that calculates a current position based upon the estimated value for the distance factor, comprising:

a continuous learning unit that updates a first estimated value for the distance factor and a first parameter, based upon

a measurement quantity, which is calculated based upon the vehicle speed pulses and the GPS information,

the first estimated value for the distance factor and

the first parameter;

a one-time learning unit that updates a second estimated value for the distance factor and a second parameter, based upon,

the measurement quantity,

the second estimated value for the distance factor and

the second parameter;

a factor comparing unit that calculates absolute value of the difference between the updated first estimated value and the updated second estimated value;

an arithmetic operation control unit that overwrites the first parameter and the first estimated value at the continuous learning unit with the second parameter and the second estimated value at the one-time learning unit when the difference between the updated first estimated value and the updated second estimated value, having been calculated, is equal to or greater than a predetermined value; and

a storage unit in which the first estimated value and the first parameter calculated by the continuous learning unit are stored with predetermined first timing, wherein;

both of the continuous learning unit and the one-time learning unit are a Kalman filter or a least-square estimator that determines the updated first estimated value or the updated second estimated value for the distance factor, based upon the first estimated value or the second estimated value previously calculated for the distance factor, current vehicle speed pulses and current GPS information, so that a value of the first parameter or the second parameter is reduced;

the continuous learning unit, started up with predetermined second timing, reads, at startup, the first estimated value and the first parameter having been stored with the predetermined first timing and starts execution of update processing to update the first estimated value and the first parameter based upon the measurement quantity, which is calculated based upon the vehicle speed pulses and the GPS information, the first estimated value and the first parameter;

the one-time learning unit, started up with the predetermined second timing, reads, at startup, an initial value for the second estimated value and an initial value for the second parameter, which are stored in advance, and starts execution of update processing to update the second estimated value and the second parameter based upon the measurement quantity, which is calculated based upon the vehicle speed pulses and the GPS information, the initial value for the second estimated value and the initial value for the second parameter;

the difference calculation unit calculates the difference between the second estimated value output after a predetermined length of time elapses following startup of the one-time learning unit and the first estimated value; and

the distance factor learning device is installed in a vehicle, the predetermined first timing is timing with which an ignition switch in the vehicle is turned off and the predetermined second timing is timing with which the ignition switch in the vehicle is turned on.

2. The distance factor learning device according to claim 1, wherein:

the continuous learning unit and the one-time learning unit adopt an algorithm whereby the first parameter and the second parameter each converge after a predetermined length of time elapses following startup of each of the continuous learning unit and the one-time learning unit; and

at a time point of the ignition switch in the vehicle being turned on, the first parameter is smaller than the second parameter.

3. The distance factor learning device according to claim 1, wherein:

the continuous learning unit and the one-time learning unit are Kalman filters and the first parameter and the second parameter each represent error variance in the first estimated value or the second estimated value for the distance factor.

4. A distance factor learning method for calculating an estimated value for a distance factor based upon a distance between a plurality of current positions obtained from GPS information, a number of vehicle speed pulses obtained while the distance is traveled, and a parameter which is an error index of the estimated value for the distance factor, and that is adopted in a current position calculation device that calculates a current position based upon the estimated value for the distance factor, comprising:

updating, by a continuous learning unit that is a Kalman filter or a least-square estimator, a first estimated value for the distance factor and a first parameter based upon

a measurement quantity, which is calculated based upon the vehicle speed pulses and the GPS information,

the first estimated value for the distance factor and

the first parameter;

updating, by a one-time learning unit that is a Kalman filter or a least-square estimator, a second estimated value for the distance factor and a second parameter based upon

the measurement quantity,

the second estimated value and

the second parameter;

calculating a difference between the first estimated value and the second estimated value; and

overwriting, with a predetermined first timing, the first parameter and the first estimated value having been updated with the second parameter and the second estimated value having been updated when the difference between the first estimated value and the second estimated value, having been calculated, is equal to or greater than a predetermined value;

wherein

the continuous learning unit and the one-time learning unit determine a current first estimated value or a current second estimated value for the distance factor, based upon the first estimated value or the second estimated value previously calculated for the distance factor, current vehicle speed pulses and current GPS information, so that a value of the first parameter or the second parameter is reduced;

the continuous learning unit and the one-time learning unit determine the updated first estimated value or the updated second estimated value for the distance factor, based upon the first estimated value or the second estimated value previously calculated for the distance factor, current vehicle speed pulses and current GPS information, so that a value of the first parameter or the second parameter is reduced;

the continuous learning unit, started up with predetermined second timing, reads, at startup, the first estimated value and the first parameter having been stored with the predetermined first timing and starts execution of update processing to update the first estimated value and the first parameter based upon the measurement quantity, which is calculated based upon the vehicle speed pulses and the GPS information, the first estimated value and the first parameter;

the one-time learning unit, started up with the predetermined second timing, reads, at startup, an initial value for the second estimated value and an initial value for the second parameter, which are stored in advance, and starts execution of update processing to update the second estimated value and the second parameter based upon the measurement quantity, which is calculated based upon the vehicle speed pulses and the GPS information, the initial value for the second estimated value and the initial value for the second parameter;

the difference calculation unit calculates the difference between the second estimated value output after a predetermined length of time elapses following startup of the one-time learning unit and the first estimated value; and

the distance factor learning device is installed in a vehicle, the predetermined first timing is timing with which an ignition switch in the vehicle is turned off and the predetermined second timing is timing with which the ignition switch in the vehicle is turned on.