CN101818653A - Received signal strength based real-time location method for people under mine - Google Patents

Abstract

The invention discloses a received signal strength based real-time location method for people under a mine, which comprises steps of: establishing wireless communicating network based on an IEEE 802.15.4 wireless network protocol in a mine channel; accessing a locator on each mine worker to the wireless communicating network to be a communicating node of the network; calculating a relative distance between a reference node and an unknown communication node according to the strength of a signal received by the reference node and sent from the unknown communication node and further calculating the position of the coordinate (x, y) of the unknown communication node when the function f (x, y) is minimum. By using the IEEE 802.15.4 wireless network technology, the invention realizes the location to people under a mine so as to ensure the safety of mine operation and provide strong support for search and rescue work after accidents.

Description

Real-time location method based on the downhole personnel of received signal intensity

Technical field

The present invention relates to a kind of localization method of radio communication, especially relate to a kind of IEEE of employing 802.15.4 radio network technique, downhole personnel carried out the method for real-time positioning based on received signal intensity.

Background technology

The heavy industry that pit mining takes place frequently as security incident, very high to the requirement of safety supervision management system.Utilize the radio communication navigation system, also following personnel are carried out the real-time positioning supervision, will strengthen the safety guarantee of underground work to a great extent.

At present, some collieries of China also rest on takes the mine lamp work attendance, and original methods such as phone track and localization are grasped the stage of staff's down-hole information, and this method can not be timely, understand underground work personnel's position and distribution situation accurately, can't adapt to the actual requirement of Safety of Coal Mine Production.In recent years, more domestic scientific research institutions and enterprise have released separately to down-hole application personnel tracking location and attendance checking system, this type systematic mainly is based on REID RFID (radio frequencyidentification), this class technology can only realize zone location, can't realize personnel in the pit's accurate location.As for adopting cable laying, then there is the cost height in the wire signal transmission means of optical cable etc., and complex-terrain district laying difficulty is bigger, the problems that flexibility is relatively poor.

In addition, the roadway passage of mine is long and narrow, closed communication channel, and since dust, humidity, the existence of reasons such as electromagnetic interference, communication condition is more abominable, mainly shows these points:

At first, multipath effect is serious.Small scale decline is meant that the electromagnetic wave that sends from emission source reflects on the surface of each obstruction, scattering, diffraction effect, thereby along multiple different paths arrival receiving terminal.The signal that receiving terminal receives be each path signal vector with.The effect that superposes and the phase difference of each path signal are closely related, spatially cancel out each other on some point, and strengthen mutually on some point, thereby cause strong quick at random fluctuation in the near field region.

Secondly, obstructed path is propagated for the signal strength signal intensity influence big.After the air line distance between travelling carriage and the receiver is blocked, have only refraction and reflection path to arrive receiving terminal, then (Received Signal StrengthIndication RSSI) can be slackened the signal strength signal intensity that obtains of reception place, thereby influences the performance of location algorithm under the mine.

Summary of the invention

The present invention proposes a kind of real-time location method of the downhole personnel based on received signal intensity, utilize IEEE 802.15.4 radio network technique to realize downhole personnel is located, thereby, and provide strong guarantee for post-disaster search and rescue work for mine operation provides safety guarantee.

The present invention has adopted following technical scheme to realize: a kind of real-time location method of the downhole personnel based on received signal intensity, and it comprises:

In mine passage, set up cordless communication network, be arranged on the communication node that the equal access to wireless communication network of each mine staff locator on one's body also becomes this network respectively based on IEEE 802.15.4 wireless network protocol;

Extrapolate relative distance between itself and the unknown communication node according to the received signal intensity of reference communication node, so calculate the unknown communication node coordinate (x, y) for make function f (x, y) get the position of minimum value:

$f(x,y)=\frac{1}{2}\underset{i=1}{\overset{N}{\mathrm{\Σ}}}{\left(g\right\{{(x-x_i)}^2+{(y-y_i)}^2\}-g\{d_i^2\left\}\right)}^2$

Wherein, with reference to communication node coordinate (x _i, y _i), function g is a nonlinear function, d _iDistance between expression unknown communication node and N the reference mode,

A is the received signal field intensity at 1 meter of range transmission node, and n is the signal attenuation coefficient, and numerical value depends on concrete signal communication environments, RSSI _iBe that i receives the signal strength signal intensity that unknown node is launched signal with reference to communication node after level and smooth, i=1 ..., N.

Wherein, the real-time location method of described downhole personnel based on received signal intensity also comprises: intensity RSSI carries out smoothing processing, RSSI to received signal _K+1=α RSSI '+(1-α) RSSI _k, RSSI wherein _kThe received signal intensity after level and smooth constantly for k with reference to communication node, the true received signal intensity of RSSI ' for sampling, α is a smoothing factor.

Wherein, smoothing factor α is 0.3.

Wherein, nonlinear function g is a square root function.

Wherein, the real-time location method of described downhole personnel based on received signal intensity also comprises: utilize and optimize algorithm the coordinate position that reckoning draws each communication node is calculated.

Wherein, optimize algorithm and be row civilian Burger-Ma Kuaerte (Levenberg-marquardt) algorithm.

Wherein, cordless communication network is tree-shaped, starlike or mesh network topology.

Wherein, cordless communication network is formed one of them router of locator wireless access by a base station and several routers.

Compared with prior art, the present invention has following beneficial effect:

As long as each mine operation personnel carries the locator of a ZigBee mixed-media network modules mixed-media terminal, become a node in the ZigBee network, promptly can utilize the present invention to realize the location of personnel positions fast.Because ZigBee mixed-media network modules mixed-media terminal has the little and high advantage of communication efficiency of power, be very suitable for the mine passage environment and use.

Description of drawings

Fig. 1 is a schematic flow sheet of the present invention.

The specific embodiment

Common signal framing method has the method based on received signal intensity (RSSI), and (Angle OfArrival, method AOA) is based on time of arrival (toa) (Time Of Arrival, method TOA) etc. to arrive angle based on signal.Wherein, few based on the localization method of RSSI to the requirement of system hardware, realize simplely, so the present invention has adopted the method based on RSSI to position processing.

The present invention proposes a kind of downhole personnel localization method of the Zigbee of utilization technology, for downhole personnel Information Statistics and post-disaster search and rescue work provide strong guarantee.

Step S101, set up wireless network based on the communication of IEEE 802.15.4 wireless network protocol at mine passage.

One or more networks with network structure such as tree-shaped, starlike or netted are set in mine passage, and each network is made up of a base station and several routers; The base station is arranged on the initiating terminal of network, by certain communication distance a plurality of routers are set along the network bearing of trend, the mine staff locator (for ZigBee mixed-media network modules mixed-media terminal) is set on one's body, thereby, between base station, router and locator, adopt ZigBee wireless network to communicate, and the main control system on base station and the mine communicate by Ethernet or RS485 communication protocol based on IEEE 802.15.4 wireless network protocol.

The node of below mentioning, receiving terminal and transmitting terminal all adopt ZigBee mixed-media network modules mixed-media terminal, and reference mode refers to base station and router in the ZigBee wireless network, thereby adopts the self-organization network communication mode to constitute the network of a networking flexibility, reliable communications between each ZigBee mixed-media network modules mixed-media terminal.

Step S102: employing is smoothly handled to RSSI, to improve the accuracy of location.

In position fixing process, unknown node is not stopped paying out and is penetrated wireless signal, because mine wireless channel conditions down is more abominable, often signal is beated apparent in viewly, therefore can adopt level and smooth method, utilizes a part of information of signal.Smoothing method can be described as:

RSSI _K+1=α RSSI '+(1-α) RSSI _k(formula 1.1)

RSSI wherein _kThe RSSI value that is used to calculate in the etching system during for k.The true RSSI data of RSSI ' for sampling, α is a smoothing factor; Among the preferential embodiment of the present invention, get α=0.3.

Step S103:, calculate the relative distance between each node (corresponding to the operating personnel of each mine) and the reference mode based on the localization method of RSSI.

Unknown node can be calculated according to receiving RSSI of signals numerical value to the relative distance between the reference mode, thus the coordinate of calculating unknown node.Propagation models of electromagnetic wave propagation in the free space can be abbreviated as:

RSSI=-(10nlog ₁₀D+A) (formula 1.2)

Wherein A is the received signal field intensity at 1 meter of range transmission end, and n is the signal attenuation coefficient, and d is the distance of receiving terminal and transmitting terminal.

The position of supposing unknown node is for (x, y), the coordinate of N reference mode is (x ₁, y ₁), (x ₂, y ₂) ... (x _N, y _N), they are d to the distance between the unknown node ₁, d ₂..., d _N

Following formula is then arranged:

$\left\{\begin{array}{c}{(x-x_1)}^2+{(y-y_1)}^2=d_1^2\\ \·\·\·\\ {(x-x_N)}^2+{(y-y_N)}^2=d_N^2\end{array}\right.$ (formula 1.3)

D wherein _i(i=1 ..., N) can obtain through counter pushing away by the RSSI of received signal:

$d_i={10}^{(-\frac{A+\mathrm{RSS}{I}_i}{10n})}$ (formula 1.4)

In the two-dimensional space location, to know the reference mode coordinate more than three at least, therefore, the equation group in the formula (1.5) is a transcendental equation.Consider the existence of noise, the problem of separating this equation can change one into asks optimal solution, selects cost function to be:

$f(x,y)=\frac{1}{2}\underset{i=1}{\overset{N}{\mathrm{\Σ}}}{\left(g\right\{{(x-x_i)}^2+{(y-y_i)}^2\}-g\{d_i^2\left\}\right)}^2$ (formula 1.6)

Wherein g{} is a nonlinear function, and different nonlinear functions can be regulated cost function to the sensitivity of noise and result's error range.In a preferred embodiment of the invention, be chosen as square root function, i.e. g{}=sqrt ().

Then make function f (x, y) Zui Xiao position (x ', y ') be the unknown node position (x, being estimated as y):

$(x^{\′},y^{\′})=\arg \underset{x,y}{\min }f(x,y)$ (formula 1.7)

Step S104: utilize the optimization algorithm that the accurate position that reckoning draws each node is calculated, try to achieve final positioning result.

To function f (x, optimization y) is converted into a least square problem, make x=(x, y) ^TBe the unknown parameter vector, then cost function can be rewritten as:

$f\left(x\right)=\frac{1}{2}\underset{i=1}{\overset{N}{\mathrm{\Σ}}}{r}_i{\left(x\right)}^2$ (formula 1.8)

Wherein, r (x) is expressed as:

R (x)=(r ₁(x) ..., r _N(x)) ^T(formula 1.9)

$r_i\left(x\right)=g\{{(x-x_1)}^2+{(y-y_1)}^2\}-g\left\{d_i^2\right\},i=1,...,N$ (formula 1.10)

Then following formula can adopt row civilian Burger-Ma Kuaerte (Levenberg-marquardt) method to carry out iterative, and its iterative formula can be written as:

(J (x ^(k)) ^TJ (x ^(k)The d=-J of)+vI) (x ^(k)) ^TR (x ^(k)) (formula 1.11)

Wherein J (x) is Jacobi (Jacobi) matrix of r (x), is expressed as:

$J\left(x\right)=\left(\begin{array}{ccc}\frac{{\∂r}_1}{\∂x}& \·\·\·& \frac{{\∂r}_n}{\∂x}\\ \frac{{\∂r}_1}{\∂y}& \·\·\·& \frac{{\∂r}_n}{\∂y}\end{array}\right)$ (formula 1.13)

And v＞0th needs the parameter of adjusting in the iterative process.

Therefore,, become a node in the ZigBee network, promptly can utilize the present invention to realize the location of personnel positions fast as long as each mine operation personnel carries a ZigBee mixed-media network modules mixed-media terminal.Because ZigBee mixed-media network modules mixed-media terminal has the little and high advantage of communication efficiency of power, be very suitable for the mine passage environment and use.

Claims (8)

1. the real-time location method based on the downhole personnel of received signal intensity is characterized in that, comprising:

In mine passage, set up cordless communication network, be arranged on the communication node that the equal access to wireless communication network of each mine staff locator on one's body also becomes this network respectively based on IEEE 802.15.4 wireless network protocol;

The transmit signal strength that receives the unknown communication node according to reference mode is extrapolated the relative distance between itself and the unknown communication node, so calculate the unknown communication node coordinate (x, y) for make function f (x, y) get the position of minimum value:

$f(x,y)=\frac{1}{2}\underset{i=1}{\overset{N}{\mathrm{\Σ}}}{\left(g\right\{{(x-x_i)}^2+{(y-y_i)}^2\}-\{d_i^2\left\}\right)}^2$

Wherein, be (x with reference to the communication node coordinate _i, y _i), function g is a nonlinear function, d _iDistance between expression unknown communication node and N the reference mode, $d_i={10}^{\left(\frac{A+{\mathrm{RSSI}}_i}{10n}\right)},$ A is the received signal field intensity at 1 meter of range transmission node, and n is the signal attenuation coefficient, RSSI _iBe that i receives the signal strength signal intensity that unknown node transmits with reference to communication node after level and smooth, i=1 ..., N.

2. according to the real-time location method of the described downhole personnel based on received signal intensity of claim 1, it is characterized in that also comprise: intensity is carried out smoothing processing, RSSI to received signal _K+1=α RSSI '+(1-α) RSSI _k, RSSI wherein _kBe the k received signal intensity of reference mode after level and smooth constantly, the true received signal intensity of RSSI ' for sampling, α is a smoothing factor.

3. according to the real-time location method of the described downhole personnel based on received signal intensity of claim 2, it is characterized in that smoothing factor α is 0.3.

4. according to the real-time location method of the described downhole personnel based on received signal intensity of claim 1, it is characterized in that nonlinear function g is a square root function.

5. according to the real-time location method of the described downhole personnel based on received signal intensity of claim 1, it is characterized in that, also comprise: utilize and optimize algorithm the coordinate position of each communication node is calculated.

6. according to the real-time location method of the described downhole personnel based on received signal intensity of claim 5, it is characterized in that, optimize algorithm and be row civilian Burger-Ma Kuaerte algorithms.

7. according to the real-time location method of the described downhole personnel based on received signal intensity of claim 1, it is characterized in that cordless communication network is tree-shaped, starlike or mesh network topology.

8. according to the real-time location method of the described downhole personnel based on received signal intensity of claim 1, it is characterized in that cordless communication network is formed one of them router of locator wireless access by a base station and several routers.

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