Method for positioning a to-be-positioned device

• US 9,568,586 B2
• Filed: 03/07/2016
• Issued: 02/14/2017
• Est. Priority Date: 04/13/2015
• Status: Active Grant

• Current Assignee: National Chiao Tung University (Government of The Republic of China)
• Original Assignee: National Chiao Tung University (Government of The Republic of China)
• Inventors: Hu, Jwu-Sheng, Sun, Kuan-Chun
• Primary Examiner(s): Marc, McDieunel
• Application Number:
  US15/063,239
• Publication Number:
  US 20160299209A1
• Time in Patent Office: 344 Days
• Field of Search: 701/408, 342/351.61, 342/357.69
• US Class Current: 1/1
• CPC Class Codes: G01C 21/1654 with electromagnetic compass
• CPC Class Codes: G01C 21/206 specially adapted for indoor navigation
• CPC Class Codes: G01S 2205/02 Indoor
• CPC Class Codes: G01S 5/02 using radio waves using satellite radio beacon systems for determining position G01S19/00
• CPC Class Codes: G01S 5/0284 Relative positioning

Abstract

A method for positioning a device includes the steps of: estimating an absolute distance between a reference point and the device at each of a current time point and a number (N) of consecutive previous time points, where N is a integer smaller than n, n is a non-negative integer indicating a total number of time points since the device starting to move, and the current time point is defined as the (n)^th time point; estimating a unit vector of a movement direction of the device in each of (n−N+1)^th to (n)^th time periods; and estimating a coordinate of a location of the device at (n)^th time point based on the absolute distance(s), the unit vector(s), and a coordinate of a location of the device at each of the number (N) of the consecutive previous time points.

Claims

1. A method for positioning a to-be-positioned device, the method to be implemented by a positioning system that includes a distance estimating unit, an orientation estimating unit disposed on the to-be-positioned device, and a processing unit coupled to the distance estimating unit and the orientation estimating unit, the method comprising the steps of:

a) estimating, by the distance estimating unit, an absolute distance between a reference point and the to-be-positioned device at each of a current time point and a number (N) of consecutive previous time points before the current time point, where N is an integer smaller than n, n is a non-negative integer indicating a total number of time points accumulated since the to-be-positioned device starts to move, the current time point is defined as the (n)^th time point, a (j)^th time period is defined as a time period between (j−

1)^th and (j)^th time points, and j is an integer ranging from 1 to n;

b) estimating, by the orientation estimating unit, a unit vector of a movement direction of the to-be-positioned device in each of (n−

N+1)^th to (n)^th time periods; and

c) estimating, by the processing unit, coordinates of a location of the to-be-positioned device at the (n)^th time point based on the absolute distance(s) estimated in step a), the unit vector(s) estimated in step b), and coordinates of a location of the to-be-positioned device at each of the number (N) of the consecutive previous time points.

2. The method of claim 1, wherein in step c), the processing unit is programmed to calculate a moving distance (α

_n) that the to-be-positioned device has moved in the (n)^th time period according to the following equation;

3. The method of claim 2, wherein α

_n satisfies one of the following conditions;

when ε

_n>

0, α

_n is a positive value; and

when {right arrow over (d)}_n^T{right arrow over (x)}_n<

0 and ε

_n<

0, α

_n has two positive value solutions and the smaller one of α

_n is selected as the moving distance.

4. The method of claim 3, wherein in step c), the coordinates are in a two-dimensional X-Y Cartesian coordinate system, and the reference point is given as the origin of the Cartesian coordinate system,

wherein, in step b), the orientation estimating unit is configured to estimate an angle between the movement direction and a reference direction that is parallel to an X-axis of the Cartesian coordinate system, so as to obtain the unit vector of the movement direction.

5. The method of claim 4, wherein, step c), the processing unit is programmed to further determine a measurement vector (z_n) associated with the location of the to-be-positioned device, and a status vector (x_n) associated with the moving distance of the to-be-positioned device in the (n)^th time period by the following equations:

6. The method of claim 3, wherein in step c), the processing unit determines α

_n and x_n via a filtering process.

7. The method of claim 3, wherein in step c), the coordinates are in a three-dimensional X-Y-Z Cartesian coordinate system, and the reference point is given as the origin of the Cartesian coordinate system,

wherein, in step b), the orientation estimating unit is configured to estimate an angle between the movement direction and a reference direction that is parallel to an X-axis of the Cartesian coordinate system, so as to obtain the unit vector of the movement direction.

8. The method of claim 7, wherein, in step c), the processing unit is programmed to further determine a measurement vector (z_n) associated with the location of the to-be-positioned device and a status vector (x_n) associated with the moving distance of the to-be-positioned device in the (n)^th time period by the following equations:

9. The method of claim 8, wherein in step c), the processing unit determines α

_n and x_n via a filtering process.