JP4991279B2 - Autonomous mobile device - Google Patents

Description

  The present invention relates to an autonomous mobile device.

    Conventionally, a technique for obtaining the position of a mobile station by receiving radio waves from a mobile station at a plurality of base stations whose positions are known and using the relationship of the arrival directions of radio waves from the mobile stations detected at each base station Is known (see, for example, Patent Document 1).

  This Patent Document 1 discloses a positioning method in which positioning is performed in each mobile station using an existing positioning system such as Loran or GPS, and a positioning result is transmitted to a base station or another mobile station through communication means. In the case of determining the position of the mobile station on the base station side, there is a disclosure of a positioning method sharing the radio wave for determining the position at the base station and the radio wave for notifying the mobile station of the position. However, in the former positioning method, It is necessary to separately provide a receiver such as GPS, and there are problems such as an increase in cost, weight, and volume.

  On the other hand, in the latter, although the former problem can be solved, there is a problem that the mobile station cannot know its own position.

As the positioning method to solve these problems, a positioning method of determining the position by a DOA estimation algorithm MUSIC DOA Estimation Using (MU ltiple SI gnal C lassification) method are also provided (e.g., Patent Document 2).
JP-A-9-119970 Japanese Patent Laid-Open No. 2006-234683

  By the way, in the MUSIC method which requires setting of the number of incoming waves disclosed in Patent Document 2, a multipath in which a direct wave and a reflected wave are received simultaneously due to an influence of a phenomenon that can actually occur such as diffraction and reflection of radio waves. There is a problem that a correct direction-of-arrival estimation result cannot be obtained in an environment where it is undecided how much radio waves will arrive like the environment.

  The present invention has been made in view of the above points, and an object thereof is an autonomous mobile device that can perform accurate positioning even in a multipath environment and can accurately travel on a travel route. Is to provide.

In order to achieve the above-mentioned object, in the invention of the autonomous mobile device according to claim 1, a traveling means, a positioning section for positioning based on radio waves received from at least three radio wave transmitters at known positions, and a map of a positioning area A storage unit that stores information; a travel generation unit that generates a travel route based on the map information; a travel control unit that controls the travel unit based on the generated travel route; and a current operation based on the operation of the travel unit A dead reckoning means for estimating a position, wherein the dead reckoning means is an autonomous mobile device that corrects a current position based on a result of positioning by the positioning section, and the positioning section is in an absolute coordinate system defined in a plane. be those detected using the arrival direction of radio waves from at least three radio transmitters are arranged to coordinate positions in a known position, and three selection the radio transmitters, the electrostatic If for at least one of the transmitter are multiple arrival direction of radio waves, radio transmitters of the known positions of a plurality of the coordinate positions obtained by using the arrival direction of radio waves from three of said radio transmitters the selected together determine the existence direction of the radio transmitter when looking into, and arrival direction by matching the arrival direction and the presence azimuth and there orientation characterized by employing the determined the coordinates position and the aligned.

  According to the invention of the autonomous mobile device of the first aspect, the positioning unit can perform accurate positioning even in a multipath environment, and as a result, the vehicle can travel accurately with respect to the travel route.

In the invention of the autonomous mobile device according to claim 2, in the invention of claim 1, the positioning unit periodically estimates the direction of arrival using the spectrum of the radio wave intensity with respect to the direction, and is estimated at the time of the previous positioning. Further, the present invention is characterized in that a region where the spectrum of the radio wave intensity with respect to the direction is present is limited based on its own direction and the position of the radio wave transmitter.

  According to the invention of the autonomous mobile device of the second aspect, the positioning unit can periodically filter the spectrum, and as a result, the positioning time in the positioning unit can be shortened.

  In the invention of the autonomous mobile device according to claim 3, in the invention of claim 1, the autonomous mobile device further includes an ambient environment determination unit that determines whether or not the device exists in an area where multipath is likely to occur, and the positioning unit includes: In an area where there is a low possibility of multipath, arrival direction estimation is performed without considering multipath.

  According to the invention of the autonomous mobile device according to claim 3, the positioning time of the positioning unit can be shortened by determining whether or not to consider multipath according to the surrounding environment.

  The present invention has an effect that the positioning unit can perform accurate positioning even in a multipath environment, and as a result, the vehicle can travel with high accuracy on the travel route.

  Embodiments of the present invention will be described below.

FIG. 1 shows a configuration of an autonomous mobile device 1 of the present embodiment, and the autonomous mobile device 1 is transmitted from a radio wave transmitter 2 (2 ₁ to 2 ₃ ) arranged in a traveling area as shown in FIG. A radio wave is received through the antenna 30, and a positioning unit 3 that performs positioning based on the direction of arrival of the received radio wave, a storage unit 4 that stores map information Map of the operation area, and a travel route is generated based on the map information Map. A route generation unit 5 that performs the control, a travel control unit 7 that controls the travel unit (such as an electric motor and a travel wheel) 6 based on the generated travel route, and dead reckoning that estimates the current position based on the operation of the travel unit 6 Part 8.

  As shown in FIG. 1, the positioning unit 3 extracts and extracts an antenna 30 that receives a radio wave from the radio wave transmitter 2 (see FIG. 2) and a component for detecting the arrival direction of the radio wave from the output of the antenna 30. An antenna signal processing circuit unit 31 having a function of converting a component into a digital signal for subsequent processing, and a radio wave arrival direction for estimating the arrival direction of the radio wave in the antenna coordinate system using the output of the antenna signal processing circuit unit 31 An estimation unit 32 and a parameter storage unit 33 that stores parameters for radio wave arrival direction estimation are provided. Further, since the positioning unit 3 needs to know the coordinate position of the radio wave transmitter 2 in order to obtain the coordinate position in the absolute coordinate system, the transmitter coordinate memory in which the coordinates of the radio wave transmitter 2 in the absolute coordinate system are registered in advance. A positioning algorithm for determining the coordinate position of the positioning unit 3 using the arrival direction estimated by the radio wave arrival direction estimating unit 32 and the coordinate position of the radio wave transmitter 2 registered in the transmitter coordinate storage unit 34 is provided. A processing unit 35 is provided.

  The coordinate position of the positioning unit 3 is the coordinate position of the representative point of the positioning unit 3. In the following description, the coordinate position of the origin of the antenna coordinate system set with the antenna 30 provided in the positioning unit 3 as a reference is expressed as an absolute coordinate. It shall be used for the coordinate position of the positioning unit 3 in the system.

  The antenna 30 is configured to be able to detect the arrival direction of radio waves. In the present embodiment, a plurality of antenna elements 30a (four in the illustrated example at equal intervals on the circumference) are used as a basis. An array antenna having a shape standing on the table 30b is used. Each antenna element 30a is a monopole, and in the example shown in the figure, four equal intervals are provided upright on the circumference of one surface of a base 21b. The origin of the antenna coordinate system is the center of the part surrounded by the antenna element 30a, that is, the center of the circle.

  The output of the antenna 30 is input to the antenna signal processing circuit unit 31. As shown in FIG. 2, the antenna signal processing circuit unit 31 includes an attenuator that switches a gain for each antenna element 30a, and a high-frequency circuit unit RF that includes a mixing circuit that converts a signal received by the antenna element 30a to a constant frequency. A local oscillation circuit SG for supplying a local oscillation signal to the mixing circuit, and an A / D conversion unit AD for converting the output of the mixing circuit into a digital signal.

  The same number of attenuators and mixing circuits of the high-frequency circuit section RF as the antenna elements 30a are provided. The mixing circuit also has a function of IQ separation (separation of real and imaginary components). The mixing circuit performs down-conversion, and the mixing circuit performs frequency conversion to a constant frequency by changing the frequency of the local oscillation signal output from the local oscillation circuit SG (local oscillation frequency). Therefore, by providing a band-pass filter that passes a predetermined frequency at the output of the mixing circuit, only the component corresponding to the local frequency is output from the mixing circuit in the signal received by the antenna element 30a. That is, the component corresponding to the radio wave from the radio wave transmitter 2 can be extracted from the mixing circuit by changing the local oscillation frequency. The output of the high-frequency circuit unit RF, that is, the output frequency of the mixing circuit is set to a frequency suitable for sampling in the A / D conversion unit AD (a frequency equal to or less than half the sampling frequency).

  The A / D conversion unit AD converts the real number component and the imaginary number component output from the high frequency circuit unit RF into digital values, respectively. For the A / D converter AD, the sampling frequency, the number of sampling points, and the number of output bits are, for example, 10 MHz, 1000 points, and 12 bits. Since the radio wave transmitter 2 transmits radio waves of different frequencies, the A / D converter AD performs sampling for the number of sampling points for each frequency. In the present embodiment, the reception frequency is switched three times on the assumption that radio waves from the three radio wave transmitters 2 are received. Note that the reception frequency is selected according to the current position of the positioning unit 3 so as to receive radio waves from the radio wave transmitter 2 existing at a short distance.

  The output of the A / D conversion unit AD is input to a DSP (digital signal processor) 300 that realizes the function of the radio wave arrival direction estimation unit 32. The DSP 300 estimates the arrival direction of the radio wave using the real component and the imaginary component of the radio wave received by the antenna element 30a. On the other hand, the transmitter coordinate storage unit 34 in which the coordinate position of the positioning unit 3 in the absolute coordinate system O-XY is registered is realized by an internal memory (not shown) attached to the DSP 300. The transmitter coordinate storage unit 34 stores the frequency of the transmission signal from the radio wave transmitter 2 in addition to the coordinate position of the radio wave transmitter 2, and the three radio wave transmitters 2 located at a short distance from the positioning unit 3. And the local oscillation frequency of the local oscillation circuit SG can be selected according to the frequency of the radio wave transmitter 2.

  The DSP 300 also has a function as the positioning algorithm processing unit 35, and the radio wave arrival direction 2 obtained from the real component and the imaginary component output from the A / D conversion unit AD and the radio wave transmitter 2 registered in the internal memory. Is used to calculate the coordinate position of the positioning unit 3 in the absolute coordinate system. The calculation result is sent to the control unit 9 composed of a microcomputer via the communication unit 10.

  This control unit 9 constitutes a route generation unit 5, a travel control unit 7, and a dead reckoning unit 8. From the DSP 300, in addition to the coordinate position, the arrival direction of radio waves and the received power at each antenna element 30a are also output. Is done.

  In the positioning unit 3, it is necessary to change the local oscillation frequency for each radio wave transmitter 2, but it is necessary to change the reception condition of the antenna 30 while detecting the arrival direction of the radio wave from one radio wave transmitter 2. Therefore, for each radio wave transmitter 2, it is possible to estimate the arrival direction of radio waves in a short time that can be regarded as substantially the same time. That is, in the positioning unit 3, the relative position between the radio wave transmitter 2 and the antenna 30 may fluctuate, but the time required to collect data necessary to estimate the arrival direction of the radio wave from each radio wave transmitter 2 is Since it is short, the arrival direction can be estimated in a short time such that the arrival direction of radio waves does not fluctuate.

  The dead reckoning unit 8 includes a gyro sensor 80 that measures the rotation angle Δθ (t) of the autonomous mobile device 1 and a vehicle speed sensor 81 that measures the travel distance (Δx (t), Δy (z)) of the autonomous mobile device 1. And a movement distance / rotation angle calculation means 82 for calculating the movement distance and rotation angle of the autonomous mobile device 1 from the detection outputs of the sensors 80 and 81 and estimating the current position. A means for calculating Δθ (t) based on the difference between the rotational speeds of the left and right wheels of the traveling means 6 may be provided instead of the gyro sensor 80.

  Next, a method for obtaining the coordinate position of the autonomous mobile device 1 will be described in detail using the conceptual diagram of the positioning system of FIG.

FIG. 3 detects the position of the autonomous mobile device 1 as the coordinate position of the absolute coordinate system O-XY defined for the target space (target plane) for positioning. Specifically, the direction in which radio waves arrive at the positioning device 2 from the _three radio wave transmitters 2 (2 ₁ to 2 ₃ ) whose coordinate positions in the absolute coordinate system O-XY are known is detected, and each radio wave transmission The coordinate position of the positioning device 2 in the absolute coordinate system O-XY is detected based on the arrival direction of the radio wave from the device 2 and the known coordinate position of each radio wave transmitter 2 (2 ₁ to 2 ₃ ). In order to distinguish the radio waves from the radio wave transmitters 2 ₁ to 2 ₃ in the positioning device 2, the radio waves transmitted from the radio wave transmitters 2 ₁ to 2 ₃ are set to different frequencies.

  Since the positioning unit 3 cannot specify the arrival direction of radio waves in the absolute coordinate system O-XY, the positioning unit 3 detects the arrival direction of radio waves in the antenna coordinate system O′-X′Y ′ set for the autonomous mobile device 1. The X′Y ′ plane of the antenna coordinate system O′-X′Y ′ is assumed to be coincident with or parallel to the XY plane of the absolute coordinate system O-XY.

Thus, now in FIG. 3, the three radio wave transmitters 2 ₁ to 2 ₃ are known points P ₁ (x ₁ , y ₁ ), P ₂ (x ₂ , y ₂ ), P ₃ (x ₃ , y ₃ ). At that time, the radio wave arrival direction estimation result from the point P ₁ (x ₁ , y ₁ ) is φ ₁ a, φ ₁ b, P ₂ (x ₂ , y ₂ ) is the radio wave arrival direction estimation result is φ ₂ , P in _{3 (x} 3, _{y 3)} DOA estimation result phi ₃ from, and the coordinate values of the respective radio transmitters 2 ₁ to 2 ₃ DOA estimation result and the positioning result obtained as shown in Table 1 To do. Incidentally radio transmitters 2 _1, there is set a direct wave and reflected wave both, 2 1 _a, 2 1 _b is a code indicating to distinguish between direct and reflected waves.

The positioning algorithm processing unit 35 of the positioning unit 35 performs self-position estimation using a known Cassini solution, and selects three each of which overlaps the combination. In the example of Table 1 above, 2 ₁ a, 2 ₂ , 2 ₃ and 2 ₁ b, 2 ₂ , 2 ₃ are used. At this time, the following determination is performed on the set of 2 ₁ a, 2 ₂ , 2 _{3 and} the set of 2 ₁ b, 2 ₂ , 2 ₃ .

The radio wave transmitters 2 _{1 to} 2 ₃ are present at three locations of P ₁ (x ₁ , y ₁ ), P ₂ (x ₂ , y ₂ ), and P ₃ (x ₃ , y ₃ ), and the arrival direction estimation angle is When φ ₁ a, φ ₁ b, φ ₂ , and φ ₃ are used, the positioning results are as follows.

P ₁ , P ₂ , P ₃ , φ ₁ a, φ ₂ , φ ₃ ⇒x1a23, y1a23, θ1a23
P ₁ , P ₂ , P ₃ , φ ₁ b, φ ₂ , φ ₃ ⇒x1b23, y1b23, θ1b23
Radio wave transmitter coordinates: P _i (x _i , y _i ) (i = 1, 2, 3)
Orientation of the radio transmitters P_ _i viewed from the positioning position P_ _t (θ _{t, i)} is as shown by the number 1.

With correct positioning result t, geometrically θt, i = θt + θi
Since holds, all i contained in the t (t = 1a2 3 of al i = 1a, 2,3, t = 1b23 if i = 1b, 2,3) if satisfied the above expression, the combination of t Is a correct positioning result, and if the above equation is not satisfied for at least one i, the t is removed as an incorrect positioning result. That is, the function of removing the abnormal positioning result of the positioning algorithm processing unit 35 works.

  Here, Table 2 shows results obtained by processing the positioning results in Table 1 by the above-described algorithm.

  In Table 2, the radio wave transmitter 2 corresponding to the estimated arrival direction is indicated only by the suffix. In addition, in the tables shown below, they are similarly indicated by subscripts. “OK” indicates adoption, and “NG” indicates non-adopted positioning results.

Therefore, as a result of the determination process, a combination of 1a, 2, 3 is selected, and a correct positioning result is obtained as (x, y, θ) = (10, 10, 0). If the radio wave arrival direction estimating angle from radio transmitters 2 ₂ becomes two, phi _{2 a,} if phi _{2 b} is obtained, as the combination of the radio transmitters 2, (2 1 _a, 2 ₂ a, 2 ₃ ), (2 ₁ b, 2 ₂ a, 2 ₃ ) (2 ₁ a, 2 ₂ b, 2 ₃ ), (2 ₁ b, 2 ₂ b, 2 ₃ ). Table 4 lists all the four combinations at this time.

If the results of determination processing for these four combinations are as shown in Table 4, only the combinations of 2 ₁ a, 2 ₂ a, and 2 ₃ are adopted, and the positioning results (x, y, θ) = (10, 10, 0).

  As described above, the positioning algorithm processing unit 35 of the positioning unit 3 separates the direct wave and the reflected wave and eliminates the inappropriate angle of the arrival direction estimation angle, thereby obtaining the positioning result using the reflected wave. Removal (NG) enables accurate positioning in a multipath environment.

  Thus, when the route generation unit 5 of the autonomous mobile device 1 generates a travel route to move to a point designated from the outside based on the map information Map in the storage unit 4, the accurate positioning obtained by the positioning unit 3. Based on the result and the current position estimated by the dead reckoning unit 8, a deviation of the travel route is calculated and the deviation is corrected.

  As a result, the autonomous mobile device 1 of the present embodiment can travel accurately with respect to the travel route.

Since the Cassini solution used in this embodiment is known, the description thereof is omitted.
(Embodiment 2)
In this embodiment, the same configuration as that of the first embodiment is used, but positioning by the positioning unit 3 is sequentially performed every predetermined time, and the position at the next positioning and the direction are detected by the vehicle speed sensor 81. Guess from the speed to do. Using the estimated position and direction, the map information Map is collated, and the direction of the radio wave transmitter 2 used for positioning is estimated.

The method by which the positioning algorithm processing unit 35 of the positioning unit 3 estimates the direction of the radio wave transmitter 2 at the next positioning will be further described with reference to FIG. 4. The position of the autonomous mobile device 1 is Robot (x _t1 , y _t1 ). when, for example, I guess the location of the next positioning _{(x t2, y} t2) from the speed of the vehicle speed sensor 81 detects, each radio transmitters ₂ 1 to 2 ₃ of the direction of the time (φd, φe, φf) estimates To do. Then, the positioning algorithm processing unit 35 detects the spectrum of the radio wave intensity with respect to the direction using, for example, the known Capon method for each of the radio wave transmitters 2 ₁ to 2 ₃ as shown in FIGS. 5 (a) to (c). Although it is used for positioning calculation, the above-described estimated range is set for the detected spectrum, and other than that range is not used for positioning calculation. In FIG. 5, φa to φc indicate moving directions at the current position.

  That is, in this embodiment, the processing time by positioning is shortened by filtering the broken line portions in FIGS. 5 (a) to 5 (c).

Since the Capon method is known, the description is omitted. Since other configurations are the same as those of the first embodiment, illustration is omitted.
(Embodiment 3)
The autonomous mobile device 1 of the present embodiment uses map information in which a place (α) where multipath is likely to occur as shown in FIG. 6 is used as the map information Map stored in the storage unit 4 shown in FIG. The processing unit 35 is characterized in that it has a function of performing positioning by switching between an algorithm that considers multipath as an algorithm and an algorithm that does not consider multipath but has a short processing time. Since other configurations are the same as those of the first embodiment, illustration is omitted.

  In other words, the positioning algorithm processing unit 35 compares the current position estimated by the dead reckoning unit 8 and the positioning unit 3 itself with the place (α) set in the map information Map where the multipath is likely to occur. When the multipath is likely to occur (α), an algorithm that considers the multipath is used, and in an area where the multipath is difficult to occur, the algorithm is switched to the algorithm that does not consider the multipath.

  As a result, in this embodiment, positioning is performed with an algorithm that considers this in a place (α) where multipath is likely to occur, and in a place where there is no need to consider the algorithm, the algorithm is not considered and the processing time is short. By switching, the overall positioning time can be shortened.

1 is an overall configuration diagram of Embodiment 1. FIG. FIG. 3 is a configuration diagram illustrating a specific circuit of the first embodiment. It is explanatory drawing of the positioning method using Embodiment 1. FIG. 6 is a conceptual explanatory diagram of direction estimation of a radio wave transmitter at the time of next positioning according to Embodiment 2. FIG. It is explanatory drawing of the spectrum data corresponding to each radio wave transmitter of Embodiment 2, and filtering. It is explanatory drawing of the map information used for Embodiment 3.

Explanation of symbols

1 autonomous mobile device ₂ 1 to 2 ₃ radio transmitters 3 positioning unit 30 antenna 30a antenna element 30b base 31 antenna signal processing circuit unit 32 DOA estimating unit 33 parameter storage unit 34 transmitter coordinate storage section 35 positioning algorithm processor 4 storage unit 5 route generation unit 6 travel means 7 travel control unit 8 dead reckoning unit 80 gyro sensor 81 vehicle speed sensor

Claims (3)

A traveling unit, a positioning unit that performs positioning based on radio waves received from radio wave transmitters at at least three known positions, a storage unit that stores map information of the positioning area, and a travel that generates a travel route based on the map information A generating unit; a traveling control unit that controls the traveling unit based on the generated traveling route; and a dead reckoning unit that estimates a current position based on an operation of the traveling unit. The dead reckoning unit is the positioning unit. In an autonomous mobile device that corrects the current position based on the positioning results,
The positioning unit is for detecting using the arrival direction of radio waves from at least three radio transmitters placed a coordinate position in the absolute coordinate system defined in a plane at a known position, said radio transmitter and three selection of at least one when the arrival direction of the radio waves are multiple for a plurality of the coordinates obtained using the arrival direction of radio waves from three of the radio transmitters selected in the radio transmitters present with obtaining the azimuth, the determined the coordinate position and the arrival direction by matching the arrival direction and the presence azimuth and there orientation and are aligned in each of the radio signal transmitters when the position expected to radio transmitters of the known position An autonomous mobile device characterized by adopting. The positioning unit, there is regularly performed using a spectrum of radio field intensity direction of arrival estimation with respect to the direction, the radio wave with respect to a direction based on the direction of its own estimated at the previous positioning, the position of the radio transmitters The autonomous mobile device according to claim 1, wherein a region where the intensity spectrum exists is limited.   An ambient environment determination unit that determines whether or not the device itself is present in an area where multipath is likely to occur, and the positioning unit does not consider multipath in an area where multipath is unlikely to occur The autonomous mobile device according to claim 1, wherein direction estimation is performed.

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