DIFFERENTIAL ULTRA-WIDEBAND INDOOR POSITIONING METHOD

• US 20140301427A1
• Filed: 04/03/2013
• Published: 10/09/2014
• Est. Priority Date: 04/03/2013
• Status: Active Grant

• Current Assignee: Umm Al-Qura University
• Original Assignee: Umm Al-Qura University
• Inventors: KHALAF-ALLAH, MOHAMED
• Granted Patent: US 9,407,317 B2
• Time in Patent Office: Days
• US Class Current: 375/130
• CPC Class Codes: G01S 5/021 Calibration, monitoring or correction G01S5/0252 takes precedence
• CPC Class Codes: G01S 5/0218 Multipath in signal reception
• CPC Class Codes: H04B 1/69 Spread spectrum techniques

Abstract

The differential ultra-wideband indoor positioning method provides differential positioning to increase the accuracy of ultra-wideband (UWB) based indoor position estimation. Knowledge about common errors can be learned by employment of a reference source, where the difference between its known and estimated position (differential operation in solution domain), or the difference between the known and measured ranges (differential operation in measurement domain), provides invaluable information to be utilized in reducing errors in estimating the position of the target source. Differential operation accuracy reaches far beyond the accuracy of the non-differential setting.

Claims

1. A computer-implemented differential ultra-wideband indoor positioning method, comprising the steps of:

storing in memory a precisely known position of a single reference source (RS), wherein both a target source (TS) and the single RS are transmitting ultra-wideband (UWB) signals;

acquiring times of arrival (TOA) of both the RS and the TS;

estimating range and position of the RS and the TS based on the TOA of the ultra-wideband (UWB) signals;

computing the difference between range and positioning parameters based on the stored precisely known position of the RS, and range and positioning parameters based on the estimate of the RS;

computing correction factors for the TS estimated range and position based on the computed difference of the RS range and positioning parameters; and

recalculating the TS estimated range and position based on the correction factors;

wherein sensors i involved in the acquisition of the RS and the TS TOA are common to both the TS and the RS.

2. The computer-implemented differential ultra-wideband indoor positioning method according to claim 1, further comprising the steps of:

calculating η

_i as part of said correction factors computation, said η

_i calculation being characterized by the relation;

3. A computer-implemented differential ultra-wideband indoor positioning method, comprising the steps of:

storing in memory a precisely known position of a single reference source (RS) and known positions of n ultra-wideband (UWB) sensors, wherein both a target source (TS) and the single RS are transmitting ultra-wideband (UWB) signals;

acquiring times of arrival (TOA) of both the RS and the TS;

performing a range and position parameters calculation of the RS based on the stored precisely known position of the RS, the known positions of the n UWB sensors, and the n TOA measurements, wherein the i-th UWB sensor and the RS known position parameters are respectively characterized by the relations;

S_i=[x_i,y_i,z_i]^Tand

S_RS=[x_RS,y_RS,z_RS]^T;

calculating position parameter estimates of the RS based on the TOA measurements calculation of the position parameter estimates being characterized by the relation;

{circumflex over (s)}_RS=(H^TH)<sup>−

1</sup>H^Tb_RS^m;

computing an error vector of the position estimates of the RS based on differences between the precisely known RS position and the RS position estimates, the error vector computation being characterized by the relation;

e=ŝ

_RS−

S_RS;

calculating the TS estimated position based on the TOA acquisition times, the TS estimated position calculation being characterized by the relation;

ŝ

_TS=(H^TH)<sup>−

1</sup>H^Tb_TS^m; and

performing a final TS position estimate calculation characterized by the relation;

ŝ

_TS^SD=ŝ

_TS+e=[{circumflex over (x)},ŷ

,{circumflex over (z)}]^T,

wherein the final TS position estimate calculation includes corrections based on the error vector, and sensors involved in the acquisition of the RS and the TS TOA measurements, where these sensors are common to both the TS and the RS.

4. A computer software product, comprising a non-transitory medium readable by a processor, the non-transitory medium having stored thereon a set of instructions for performing a differential ultra-wideband indoor positioning method, the set of instructions including:

(a) a first sequence of instructions which, when executed by the processor, causes said processor to store in memory a precisely known position of a single reference source (RS) and known positions of n UWB sensors, n≧

3, wherein both a target source (TS) and said single RS are transmitting ultra-wideband (UWB) signals;

(b) a second sequence of instructions which, when executed by the processor, causes said processor to acquire times of arrival (TOA) of both said RS and said TS;

(c) a third sequence of instructions which, when executed by the processor, causes said processor to estimate range and position of said RS and said TS based on said TOA of said ultra-wideband (UWB) signals and known positions of n UWB sensors;

(d) a fourth sequence of instructions which, when executed by the processor, causes said processor to compute the difference between true and estimated range and position parameters of said RS based on said stored precisely known position of said RS, known positions of n UWB sensors, and n TOA measurements;

(e) a fifth sequence of instructions which, when executed by the processor, causes said processor to compute correction factors for said TS estimated range and position based on said computed difference of said RS range and positioning parameters;

(f) a sixth sequence of instructions which, when executed by the processor, causes said processor to recalculate said TS estimated range and position based on said correction factors, wherein sensors involved in the acquisition of said RS and said TS TOA are common to both said TS and said RS.

5. The computer software product according to claim 4, further comprising:

a seventh sequence of instructions which, when executed by the processor, causes said processor to calculate η

_i, as part of said correction factors computation, said η

_i calculation being characterized by the relation;