KR100699083B1 - Positioning deduction Method - Google Patents

Abstract

The present invention relates to a position estimation method using RFID and ultrasonic time of flight (TOF) used in an active beacon sensor, and the present invention transmits an RF signal including the ID of the beacon to the beacons. And start counting and receive ultrasonic waves transmitted from the corresponding beacon, filter the received ultrasonic signals to obtain ultrasonic distance information, and process the obtained ultrasonic distance information by triangulation to position the ultrasonic receiver. By calculating the data, filtering the calculated position data, and applying the average value theorem to minimize the error of the position values, the position data is calculated, thereby obtaining reliable position data which minimizes the position estimation error.

Position estimation, active beacon sensor system, filtering, triangulation, averaging

Description

Positioning deduction method

1 is a configuration diagram of a conventional active beacon sensor system,

2 is a configuration diagram of an embodiment of the receiver of FIG. 1,

3 is a configuration diagram of an embodiment of a beacon applied to FIG. 1,

4 is a conceptual diagram for calculating a two-dimensional distance value between a receiver and a beacon,

5 is an explanatory diagram for explaining a triangulation method;

6 is an explanatory diagram showing a position of an ultrasonic receiver installed on a moving body (robot),

7A and 7B are flowcharts illustrating a position estimation method according to the present invention;

8 is an explanatory diagram for explaining a maximum / minimum value of distance data in the present invention.

<Explanation of symbols for the main parts of the drawings>

11 to 14 ..... 1st to 4th beacon

20 ..... Receiver

21 ..... Controls

22 ..... RF Transmitter

24, 25 ..... ultrasonic receiver

45 ..... Ultrasonic Transmitter

The present invention relates to position estimation, and more particularly, to a position estimation method for minimizing position measurement error caused by the influence of the external environment using RFID and ultrasonic flight time (TOF).

More specifically, the present invention relates to a position estimation method for filtering a measured distance value of each beacon, applying the value to a triangulation algorithm, calculating a position value, and then using a mean value theorem to reduce the measurement position error.

In general, when monitoring where a moving object is located in a certain environment or when instructing a robot, it is necessary to know its current position. Position measurement is classified into indoor and outdoor according to its range, and is divided into relative position measurement method and absolute position measurement method according to the measurement method.

The relative position measurement methods in the outdoors are Odometry and inertial navigation. The absolute position measurement methods in the outdoors are GPS (Global Positioning Systems), milestone navigation, and model matching. In the room, the relative position measurement method is Odometry, and the absolute position measurement method is triangulation method, landscape analysis method, and proximity method. Landscape analysis recognizes the location by using the features of the scenery observed at the detected location. In this case, there is a disadvantage in that the environmental characteristics (landscape) must be known in advance. Scenery has a completely different form depending on the observation system. For example, in the case of a computer vision system, it is an image, and in the case of a receiver using a radio signal, it is the signal strength of the radio wave. This landscape should be simplified with features that are easy to express and easy to compare. Using proximity detects a location by contact with another object whose location is already known. Detection methods include physical contact detection, wireless cell access point monitoring and automatic ID system observation.

Absolute position measurement using triangulation in indoor environment is divided into lateration method using distance measurement and angulation method based on angle measurement.

1 is a diagram illustrating a configuration of an active beacon sensor system for performing position estimation by a conventional triangulation method.

As shown in FIG. 1, four beacons 11 to 14 installed in an environment (generally a ceiling) and transmitting RF reception and ultrasonic signals, and mounted on a moving body (robot), transmit RF and the beacons 11 to 11. It consists of a receiver 20 for receiving the ultrasonic signal emitted by 14).

Here, the entire control unit of the receiver 20 is one, and only two ultrasonic receivers that receive ultrasonic waves are mounted in a straight line of the robot.

As shown in FIG. 2, the receiver 20 controls a whole system and performs coordinate calculation, an RF transmitter 22 for transmitting RFID, and an RFID generated from the RF transmitter 22. Output signals of the antenna 22 to be transmitted in the space, the two ultrasonic receivers 24 and 25 to receive the ultrasonic signals transmitted from the beacons 11 to 14 and the ultrasonic receivers 24 and 25. Amplifying circuits 26 and 27 for respectively amplifying the signal to a predetermined level, a temperature sensing unit 28 for sensing a temperature and transmitting the temperature to the control unit 21, a communication unit 29 for transmitting and receiving data, and supplying power. Power supply circuit 30, a clock circuit 31 for providing a synchronous clock, and a reset circuit 32 for system initialization.

Next, the four beacons 11 to 14, as shown in Figure 3, the control unit 41 for comparing the ID and control the ultrasonic transmission signal, the antenna 42 for receiving the RF signal, and the antenna An RF receiver 43 for processing the signal received by the processor 42 and delivering it to the controller 41, an ultrasonic transmitter circuit 44 for generating an ultrasonic signal in response to the control of the controller 41, and An ultrasonic transmitter 45 for transmitting ultrasonic waves generated by the ultrasonic transmitter circuit 44 in a space, a power supply circuit 46 for supplying power, a clock circuit 47 for providing a synchronization clock, and system initialization And a reset circuit 48 for each.

The basic position recognition method uses a conventional distance measuring method using ultrasonic waves, that is, a distance measuring method by measuring a flight time (TOF) of ultrasonic waves. The RF signal is used to synchronize transmitters and receivers, which are essential for flight time measurement. In other words, since the speed of RF is very fast compared to sound waves, the time delay of the RF signal is regarded as 0.

When there are several beacons using the same frequency, the RF signal of the receiver may malfunction if it does not distinguish which beacon ultrasonic signal is received. To prevent this, each ID is assigned to the Active Beacon Sensor. Here, when transmitting RF data in the RF transmission module mounted on the mobile robot, it transmits a predetermined identification ID. Therefore, the Active Beacon Sensor generates ultrasonic waves from the beacon when the received ID matches its ID. The reason for assigning each ID to the beacon is as follows.

1) to prevent interference between ultrasonic signals, 2) to identify each ultrasonic signal at an ultrasonic receiver, and 3) to synchronize between ultrasonic transmission / reception sensors for measuring ultrasonic flight time (TOF).

In order to prevent the interference between the ultrasonic signals, the RF transceiver module should sequentially generate the signal generation points of the ultrasonic transmitters 11 to 14, and also synchronize the ultrasonic transceiver for identifying the ultrasonic signals in the ultrasonic receiver 20. Each beacon is driven by the RFID reception corresponding to its ID. If it is determined that the RFID is given to the ultrasonic wave is sent to the receiver side, the receiver 20 receiving this is calculated for each distance by the following equation.

는 회로 지연, S는 전체 초음파 비행 시간, v는 초음파 비행 속도이며, r은 거리이다.Where T is temperature, f is count clock rate, n is timer counter,

Is the circuit delay, S is the total ultrasonic flight time, v is the ultrasonic flight speed, and r is the distance.

Triangulation is performed using the distance between the ultrasonic transmitters and receivers thus obtained. Knowing the speed of the medium (such as radio waves or sound waves) and measuring the ultrasonic time of flight (TOF) of the medium from the transmitter to the receiver, the position can be calculated. First, we need to convert the distance r value into a planar two-dimensional value.

As shown in FIG. 4, the distance value d of the two-dimensional plane on the receiver mounted on the robot may be expressed by Equation 2 below.

As shown in FIG. 5, the triangulation method can easily determine that the intersection of three circles is the current position in two dimensions if the distance from three known points can be measured.

Here, if there is only one receiver of the ultrasonic wave, it is possible to know where the moving object is located, but the attitude angle cannot be measured.

In order to compensate for this, as shown in FIG. 6, two ultrasonic receivers are attached to both the position and the direction in which the moving object is referred to in a straight line. Knowing the position of the two receivers allows us to measure the attitude angle in the reference coordinate system.

This measurement method provides reliable and accurate position detection with minimal calculation, but the ultrasonic transmitters serving as reference points should be fixed at very accurate positions. In the case of using distance measurement using ultrasonic waves, ultrasonic signals generate noise due to the influence of the external environment, and measurement errors due to reflected waves or ultrasonic reception sensitivity are generated. Due to such external environment factors, the position estimation error increases. In addition, there are errors in the sensor itself that do not have sufficient reliability for the desired position value in the sensor.

Meanwhile, in the conventional receiver, a plurality of indirect ultrasonic signals, including direct waves that arrive directly from the ultrasonic transmitter during one sampling interval, may be detected, but may not be filtered and may be used as it is, thereby causing a distance measurement error. There is a problem that an error occurs in the position estimation.

The present invention has been proposed to remove a position estimation error that occurs when the position estimation in the conventional receiver as described above,

An object of the present invention is to provide a position estimation method for minimizing position measurement error caused by the influence of the external environment using RFID and ultrasonic flight time (TOF).

More specifically, since there is a limit to the method of reducing the measurement distance error of the ultrasonic wave by receiving only the direct wave arriving directly from the ultrasonic transmitter during one sampling interval, the distance value of each measured beacon is filtered to reduce the measurement error, and the filtered The present invention provides a position estimation method for reducing a measurement position error by applying a triangulation algorithm to a value, calculating a position value, and applying an average value theorem to the calculated position value.

The "position estimation method" according to the present invention for achieving the above object,

In the position estimation method in the position estimation system comprising a first to fourth beacons provided at a predetermined position in the room (ROOM) for transmitting ultrasonic waves and a receiver for receiving the ultrasonic waves transmitted from the first to fourth beacons,

Transmitting an RF signal including the ID of the beacon to the first to fourth beacons provided at each corner of the top of the space and receiving the ultrasonic wave transmitted from the beacon;

Obtaining ultrasonic distance information by performing filtering on the received ultrasonic signal;

Calculating position data of an ultrasonic receiver by processing the obtained ultrasonic distance information by triangulation;

And calculating the position data by filtering the calculated position data and minimizing the error of the position values by applying an average value theorem.

Hereinafter, described in detail with reference to the accompanying drawings, preferred embodiments of the present invention according to the technical spirit as described above.

7A and 7B are flowcharts illustrating a position estimation method according to the present invention.

FIG. 7A is an operation flowchart of a receiver (20 of FIG. 1), and transmits an RF signal including the ID of the beacon to the first to fourth beacons 11 to 14 provided at the top corners of the space. Receiving ultrasonic waves transmitted from the beacon (S101, S103); Obtaining ultrasonic distance information by performing filtering of the received ultrasonic signal (S105); Repeating the steps (S101, S103) on all installed beacons (S107, S109); Calculating position data of the ultrasonic receiver 20 by processing the obtained ultrasonic distance information by triangulation (S111); Step S113 and S115 are calculated by filtering the calculated position data and applying an average value theorem to minimize the error of the position values.

7B is an operation flowchart of each beacon, which confirms whether an RF signal is received (S201); Waiting if an RF signal is not received as a result of the checking (S203); Comparing the ID included in the received RF signal with its own ID when the RF signal is received (S205); When the ID included in the received RF signal and its ID match as a result of the comparison is made to send an ultrasonic wave (S207).

The position estimation method according to the present invention made as described above will be described in detail with reference to the accompanying drawings.

First, the present invention transmits an RFID to a beacon, an active beacon receiver (20 of FIG. 1) for receiving an ultrasonic wave transmitted from the beacon, and an active beacon for receiving the RFID and transmitting an ultrasonic signal (Active) Beacon: 11 to 14 of FIG. 1), and the active beacon receiver includes Positioning algorithms and filtering processing algorithms.

This configuration is configured to measure the position and orientation angle of the mobile robot more quickly and precisely.

In the configuration diagram of FIG. 1, the receiver 20 uses an RF transmitting module and an ultrasonic receiving module, and the beacon uses an existing technology using an RF receiving module and an ultrasonic transmitting module. In addition, the ultrasonic distance calculation for distance measurement and the triangulation method for position measurement apply the method used in the existing global positioning system (GPS). That is, the triangulation method used in the GPS system is utilized in the present invention.

The processor for position estimation algorithm and filtering in the present invention is built in the receiver 20 side and is calculated by known appropriate procedures when performing position calculation. The calculation method also includes processing for the case where no ultrasonic signal is detected by the ultrasonic receiver, and it is assumed that it has a signal detection method and a processing function of the detected signal. This location estimation method will be explained continuously with a robot, but the Active Beacon Sensor System can be applied to moving not only a robot but also an indoor building such as a PDA, a pet, and a cart of a mart. It is readily apparent to those skilled in the art that the principles of the present invention may be equally applicable. Active Beacon System enables to calculate the coordinates and to measure the distance between the beacon installed in the ceiling corner of the indoor environment and the receiver mounted on the robot to implement the object of the present invention.

This is explained in more detail as follows.

First, it is assumed that the receiver has a built-in RF transmitting module capable of transmitting RFID and an ultrasonic receiving module capable of receiving an ultrasonic signal. In addition, it is assumed that timing programs for RF transmission and reception and ultrasonic transmission and reception are stored. The timer counter value starts at the same time as ultrasonic transmission and operates until it is received. In the program on the receiver side, this counter data becomes a reference for position and orientation angle calculations. This is taken as a reference value for position estimation.

(i = 1, 2, 3, 4)에 설치한다. 이는 삼각 측량법은 각 비컨의 좌표를 알고 있는 상황에서 수신기의 좌표를 측정하는 알고리즘이다.The first receiver 20 is installed so that the two ultrasonic receiving modules 24 and 25 of the robot are located at the center of the robot. And beacons 11 to 14 already know the coordinates of the interior space and assume fixed coordinates for each corner of the space.

(i = 1, 2, 3, 4). This is a triangulation algorithm that measures the coordinates of the receiver in situations where you know the coordinates of each beacon.

As shown in FIGS. 7A and 7B, the beacons 11 to 14 maintain the standby mode (SLEEP mode) to reduce power consumption when the position estimation is not normally performed (S203). When the receiver 20 transmits an RF signal including the ID of the 1 beacon (for example, 11) (S101), only the beacons that match the ID of the 4 beacons, that is, the 1 beacon 11 transmits the ultrasonic waves. (S201, S205, S207). At this time, the receiver 20 transmits the RFID and counting starts.

When the receiver 20 senses the ultrasonic signal, the distance is calculated using the counted time value (S101, S105).

When the ultrasonic signal is detected, the distance value is affected by the external environment, and measurement errors due to noise, reflected waves, or ultrasonic reception sensitivity are generated. That is, since the received ultrasonic signal may be wrong data, the measured distance value may not be the actual distance value, and thus the primary filtering is performed. The filtering method first removes the reflected wave of the received ultrasonic signal and receives only the direct wave to obtain reliable ultrasonic distance information. Since the direct wave always arrives before the reflected wave, the reflected wave is filtered by not receiving the ultrasonic wave for a predetermined delay after receiving the direct wave. In addition, the noise caused by the external environment is an impulse form of noise as a result of the analysis of the ultrasonic noise. Use the method. And in case the signal is completely wrong due to disturbance, the value larger than the total space and smaller than the minimum value is defined as out-of-range error and discarded. In this case, the largest value is a Dmax value as shown in FIG. 8, and the minimum value is defined as the distance Dmin from the plane of the ultrasound module to the ceiling, that is, the height. And finally, the triangulation method needs the distance data measured in three beacons, and when filtering the distance data received from two or more beacons when filtering, the receiver transmits the RFID of the beacon 1 from the beginning again. If the filtered distance data is one beacon, a position calculation is performed by triangulation using distance data from the remaining three beacons (S111). Under normal circumstances, however, the distance data will pass the above filtering in all four beacons. There is a reason why triangulation is performed by installing four beacons.

First, there are obstacles in the indoor space. There is a case where ultrasonic transmission / reception is not possible between the beacon and the ultrasonic reception module of the receiver due to an obstacle. In this case, the position estimation is performed using three beacons to ensure more reliability.

Second, as mentioned above, the distance data is received from all four beacons, but there is a sampling error in the sensor itself. It is easy for the relevant intellectuals to understand that the error increases as the distance increases. Therefore, the distance data of the incoming distance data is discarded the largest value, and triangulation is performed using the remaining three distance data. By filtering, the error of distance data between ultrasonic transmission and reception is minimized and then triangulation is applied.

Next, by applying the second order filtering and the mean value theorem with the coordinate values of the two ultrasonic receiving modules of the receiver to further minimize the error of the position data (S113, S115). If this is explained in more detail as follows.

Collect 10-15 pieces of position data of each ultrasonic receiving module obtained by triangulation. The data are discarded from the maximum and minimum values by the maximum and minimum theorem and then the remaining data is added. The sum is divided by the number of collected data and used as the final position value. Through this second-order filtering and average theorem, the error of position values is minimized in Active Beacon Sensor System. This method is suitable for rapid system estimation of real time position because signal processing or data processing does not require complicated equations or algorithms.

The final position values can be transferred to the main robot or host PC through the serial module and the Bluetooth module installed on the USB and used for the purpose.

According to the present invention described above, by applying to a mobile object (mobile robot, mobile phone, pocket PC, pets, children or the elderly) in the indoor environment more accurately estimate the real-time absolute position, and reacts insensitive to changes in the external environment It is effective to provide a position estimation system.

In addition, the application of these systems is simpler and faster in spaces that require real-time location estimation and external noise with significant external environmental changes such as educational institutions, vehicle control systems, unmanned automated factories, hospital service robots, parking lots, buildings, and homes. The advantage of guaranteeing speed is to make location recognition faster and more precise.

Claims (8)

delete In the position estimation method in the position estimation system comprising a first to fourth beacons that are provided at each top corner of the room (ROOM) for transmitting the ultrasonic waves and a receiver for receiving the ultrasonic waves transmitted from the first to fourth beacons , Transmitting a RF signal including the ID of the beacon to the first to fourth beacons, starting counting, and receiving ultrasonic waves transmitted from the beacons; A second step of obtaining ultrasonic distance information by filtering the received ultrasonic signal; A third step of calculating position data of an ultrasonic receiver by processing the obtained ultrasonic distance information by triangulation; And a fourth step of filtering the calculated position data and applying an average value theorem to minimize the error of the position values to calculate the position data. Counting in the first step, And counting until the ultrasonic wave is received after starting simultaneously with transmitting the RF signal. In the position estimation method in the position estimation system comprising a first to fourth beacons that are provided at each top corner of the room (ROOM) for transmitting the ultrasonic waves and a receiver for receiving the ultrasonic waves transmitted from the first to fourth beacons , Transmitting a RF signal including the ID of the beacon to the first to fourth beacons, starting counting, and receiving ultrasonic waves transmitted from the beacons; A second step of obtaining ultrasonic distance information by filtering the received ultrasonic signal; A third step of calculating position data of an ultrasonic receiver by processing the obtained ultrasonic distance information by triangulation; And a fourth step of filtering the calculated position data and applying an average value theorem to minimize the error of the position values to calculate the position data. The filtering of the second step, And a reflection wave is filtered by a method of not receiving an ultrasonic wave for a predetermined delay time after receiving the direct wave of the received ultrasonic signal. In the position estimation method in the position estimation system comprising a first to fourth beacons that are provided at each top corner of the room (ROOM) for transmitting the ultrasonic waves and a receiver for receiving the ultrasonic waves transmitted from the first to fourth beacons , Transmitting a RF signal including the ID of the beacon to the first to fourth beacons, starting counting, and receiving ultrasonic waves transmitted from the beacons; A second step of obtaining ultrasonic distance information by filtering the received ultrasonic signal; A third step of calculating position data of an ultrasonic receiver by processing the obtained ultrasonic distance information by triangulation; And a fourth step of filtering the calculated position data and applying an average value theorem to minimize the error of the position values to calculate the position data. The filtering of the second step, And a narrow time signal from the received ultrasonic signal to remove impulse noise. In the position estimation method in the position estimation system comprising a first to fourth beacons that are provided at each top corner of the room (ROOM) for transmitting the ultrasonic waves and a receiver for receiving the ultrasonic waves transmitted from the first to fourth beacons , Transmitting a RF signal including the ID of the beacon to the first to fourth beacons, starting counting, and receiving ultrasonic waves transmitted from the beacons; A second step of obtaining ultrasonic distance information by filtering the received ultrasonic signal; A third step of calculating position data of an ultrasonic receiver by processing the obtained ultrasonic distance information by triangulation; And a fourth step of filtering the calculated position data and applying an average value theorem to minimize the error of the position values to calculate the position data. The filtering of the second step, A method for estimating a position, comprising filtering a value larger than the total space for which the position is to be estimated and smaller than the minimum value (the distance from the plane of the ultrasonic receiver to the ceiling). In the position estimation method in the position estimation system comprising a first to fourth beacons that are provided at each top corner of the room (ROOM) for transmitting the ultrasonic waves and a receiver for receiving the ultrasonic waves transmitted from the first to fourth beacons , Transmitting a RF signal including the ID of the beacon to the first to fourth beacons, starting counting, and receiving ultrasonic waves transmitted from the beacons; A second step of obtaining ultrasonic distance information by filtering the received ultrasonic signal; A third step of calculating position data of an ultrasonic receiver by processing the obtained ultrasonic distance information by triangulation; And a fourth step of filtering the calculated position data and applying an average value theorem to minimize the error of the position values to calculate the position data. The third step, And when the distance data calculated in the second step is four, discard the largest value of the distance data and calculate the position data by applying a triangulation method using the remaining three distance data. In the position estimation method in the position estimation system comprising a first to fourth beacons that are provided at each top corner of the room (ROOM) for transmitting the ultrasonic waves and a receiver for receiving the ultrasonic waves transmitted from the first to fourth beacons , Transmitting a RF signal including the ID of the beacon to the first to fourth beacons, starting counting, and receiving ultrasonic waves transmitted from the beacons; A second step of obtaining ultrasonic distance information by filtering the received ultrasonic signal; A third step of calculating position data of an ultrasonic receiver by processing the obtained ultrasonic distance information by triangulation; And a fourth step of filtering the calculated position data and applying an average value theorem to minimize the error of the position values to calculate the position data. The fourth step, After collecting 10 to 15 pieces of position data obtained by the triangulation method of the third step, discarding the maximum and minimum values by the maximum and minimum theorem, adding the remaining data, and collecting the sum of the data. And determining the final position value as position data by dividing by the number. In the position estimation method in the position estimation system comprising a first to fourth beacons that are provided at each top corner of the room (ROOM) for transmitting the ultrasonic waves and a receiver for receiving the ultrasonic waves transmitted from the first to fourth beacons , Transmitting a RF signal including the ID of the beacon to the first to fourth beacons, starting counting, and receiving ultrasonic waves transmitted from the beacons; A second step of obtaining ultrasonic distance information by filtering the received ultrasonic signal; A third step of calculating position data of an ultrasonic receiver by processing the obtained ultrasonic distance information by triangulation; And a fourth step of filtering the calculated position data and applying an average value theorem to minimize the error of the position values to calculate the position data. The first to fourth beacons, Checking whether an RF signal is received; Maintaining a standby state when no RF signal is received as a result of the checking; Comparing the ID included in the received RF signal with its own ID when the RF signal is received as a result of the checking; And transmitting an ultrasonic wave when the ID included in the received RF signal and its ID match as a result of the comparison.

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