JPH05126932A - Device for detecting position of unmanned flying object - Google Patents

Abstract

PURPOSE:To highly accurately detect the position of an unmanned flying object with an inexpensive device. CONSTITUTION:A master station O and slave stations P, Q, and R respectively have spectrum-spread communication equipment. The slave station R is provided in an unmanned flying object and the other stations are installed on the ground. The master station O transmits radio waves which are modulated with PN codes having codes previously assigned to the slave stations. Of the slave stations P, Q, and R, only one station has the code transmitted from the master station and only the slave station having the code detects the transmission from the master station O. Upon detecting the code, the slave station transmits the radio waves modulated with the PN code having the code of the master station O. The master station O detects the answer from the slave station and measures the distance from the station O to the slave station based on the time spent until the answer is detected after transmission. By similarly measuring the distances between the master station and other slave stations and between each slave station, the coordinates of the pilotless flying object are found by calculation.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to position detection of an unmanned aerial vehicle, and in particular, there is no drift over time as seen in inertial navigation systems, and absolute position information can be obtained with respect to a reference point for measurement. Highly accurate position measurement can be constructed at low cost. For example, it can be used for forestry with unmanned helicopters, chemical spraying in agriculture, aerial photography, news media, and other applications in environments where danger is expected in manned flight.

[0002]

2. Description of the Related Art Conventionally, radio-controlled maneuvers (radio control) by a propo have been mainly used for flying unmanned aerial vehicles such as unmanned helicopters, but a method of mounting an inertial navigation device and flying a preprogrammed route is also practical. Has been converted. In this case, radio control (radio control) and inertial navigation are often used together.

However, in the radio control operated by human hands, the safety is poor due to the difficulty of seeing at a long distance, and the probability of damage is high.

When an inertial navigation system is installed, basically an unmanned aerial vehicle is required to have a structure similar to that of the inertial navigation system used for manned flight. Then, it becomes an expensive device.

FIG. 7 shows an example of the structure of an inertial navigation system (INS). In FIG. 7, the platform (stabilization platform) 1
A platform called Stable Accelerometer 2-3 and Gyro (angular velocity meter) 2-3 are arranged in the proper direction, and the outputs from these sensors are processed to stabilize the platform 1 (with respect to the ground surface). Keep it horizontal). At the same time, the computer 12 calculates the traveling direction and position of the aircraft.
In the figure, the Shula loop is a configuration for preventing the platform 1 from performing unnecessary operation due to acceleration (R is the radius of the earth). The height of the flying object is the radio altimeter,
It may be measured by other means.

Although the platform type inertial navigation system has been described above, the strapdown type is another type. This is a method in which an accelerometer, a gyro, etc. are directly attached to the machine body, the output thereof is A / D converted, and a computer performs necessary calculations such as coordinate conversion to obtain position and other information. This system does not require a mechanical part such as a platform and is relatively simple in configuration, but on the other hand,
A gyro with higher precision is required and the amount of calculation is large, so that the load on the computer is large. Furthermore, since it is attached to the machine body, it is easily affected by the vibration of the machine body. Therefore, an unmanned helicopter using a strapdown inertial navigation system lacks stability in maneuvering and has never been put to practical use.

[0007]

[Problems to be Solved by the Invention] As described above,
Conventional position measurement of unmanned air vehicles uses expensive equipment such as inertial navigation equipment. The gyro, which is the most important component among them, is a sensor that measures angular velocity, but drift that accumulates over time becomes a problem,
It is one of the causes of position error. The accelerometer also accumulates as an error over time if there is an initial bias,
After all, it appears as a position error. Therefore, when highly accurate position information is required, even an unmanned air vehicle will be a considerably expensive device.

An object of the present invention is to provide a position detecting device for an unmanned aerial vehicle that is inexpensive and relatively accurate and that eliminates the conventional drawbacks.

[0009]

Means for Solving the Problems The means provided by the present invention for solving the above-mentioned problems are a position detecting device for an unmanned aerial vehicle by a ranging system using spread spectrum communication technology. A plurality of devices are arranged, one of the plurality of spread spectrum communication devices is assigned to a master station, the other is assigned to a slave station, and one of the spread spectrum communication devices assigned to the slave station.
One is mounted on the unmanned aerial vehicle, and instructions from the master station to the slave stations are given in a transponder type in a predetermined order for each code, thereby measuring the distances between all the spread spectrum communication devices, and from the distances. The coordinates of the unmanned air vehicle are calculated.

[0010]

The present invention is an apparatus for measuring the current position of an unmanned air vehicle from the propagation time of radio waves using the spread spectrum communication system as a transponder.

A plurality of spread spectrum communication devices (for example, 3
Place one on an unmanned air vehicle. One of the spread spectrum communication devices arranged on the ground is the master station, and its position is the coordinate reference. Other devices are slave stations and operate according to instructions from the master station.

A PN code (Pseed) corresponding to a code assigned from a master station (probably O station) to a certain slave station.
Emit radio waves modulated by o noise (pseudo noise code). All the slave stations (probably P station, Q station, and R station) receive the radio wave, but only the slave station (provisionally P station) that has a matched filter matching the code. However, the signal can be detected. After a certain time, the detected slave station (P station) emits a radio wave modulated by a PN code corresponding to the code of the matched filter of the master station (O station). The parent station (O station) detects the code from the child station (P station), but after the parent station transmits the radio wave to the child station (P station), the parent station sends the code for the own station (slave station). (P
Since the time taken to receive (the one transmitted from the station) is measured, the distance to the slave station (P station) can be known from the measured time. Of course, since the specific delay time at the slave station (P station) is known in advance, this time is taken into consideration.

In this way, other slave stations (Q station, R station)
Also, by repeating transmission and reception with each code in order, the distance between the master station and the slave station can be known. On the other hand, the distance between the slave stations can be known according to this method. The coordinates of the unmanned air vehicle (R station) can be calculated based on the distances between all the stations thus obtained.

[0014]

EXAMPLES Next, examples of the present invention will be described. FIG. 1 shows a state (coordinates) in which the spread spectrum communication device is arranged.
In the figure, the reference master station is O (x ₀ , y ₀ , z
₀ ), P (x ₁ , y ₁ , z ₁ ), Q (x
₂ , y ₂ , z ₂ ), the unmanned air vehicle's child station is R (x ₃ , y
₃ , z ₃ ).

First, when a radio wave modulated by the code P is transmitted from the master station O [oscillation indicated by (1)], the slave station P detects it and, after the elapse of the characteristic time τ ₁ , codes to the master station O. It sends back the radio wave modulated by O (other stations do not detect the signal even if they receive it because the code is different). At this time, since the master station measures the time T ₀₁ from transmitting the code P to receiving the code O of the own station, the distance L ₀₁ between O and P is L _01.
Can be obtained as follows [(1) to (1
The oscillation shown in 5) is shown in FIG. 1] (1) → (2) T ₀₁ = t ₀₁ + τ ₁ + t ₁₀ = 2L ₀₁ / C + τ ₁ ∴L ₀₁
= C (T ₀₁ −τ ₁ ) / 2 where t ₀₁ : radio wave propagation time between O and P t ₁₀ : radio wave propagation time between P and O (t ₀₁ = t ₁₀ ) τ ₁ : at slave station P Peculiar time C: speed of light The subscript of each letter corresponds to the subscript of the coordinate of each station. Example: t ₀₁ is O (x ₀ , y ₀ , z ₀ ), P (x ₁ , y ₁ , z ₁ ).
Subscript 0 and the corresponding other similarly Similarly, 1 (3) → (4) T 02 = t 02 + τ 2 + t 20 = 2L 02 / C + τ 2 ∴L 02
= C (T ₀₂ −τ ₂ ) / 2

Next, between the slave stations P and Q, (5) → (6) →
Oscillation is performed in the order of (7). First, from parent station O to child station P
When the slave station P detects that,
The code Q of the slave station Q is transmitted. The slave station Q detects the code Q and transmits the code O to the master station O. Therefore, T ₀₁₂ = t ₀₁ + τ ₁ + t ₁₂ + τ ₂ + t ₂₀ = (T ₀₁ −τ ₁ ) / 2 + τ ₁ + L ₁₂ / C + τ ₂ + (T ₀₂ −τ ₂ ) / 2 ∴L ₁₂ = C {T ₀₁₂ − ( T ₀₁ + T ₀₂ ) / 2- (τ ₁ + τ ₂ ) / 2} In this case, between OPs [(1) → (2)] and between OQs [(3)
Since there is a need to distinguish it from the case of (4)], there are two methods. One is the end of OP and OQ as shown in FIG. 1, and it is the second time for slave stations P and Q to receive their own code. Even if the code is used, the order can be distinguished as (5) → (6) → (7). The second method changes all codes as shown in FIG. This method improves reliability but increases the number of matched filters. Similarly for other distances, (8) → (9) L ₀₃ = C (T ₀₃ −τ ₃ ) / 2 (10) → (11) → (12) L ₁₃ = C {T ₀₃₁ − (T ₀₃ + T ₀₁ ) / 2- (τ ₃ + τ ₁ ) / 2} (13) → (14) → (15) L ₂₃ = C {T ₀₃₂ − (T ₀₃ + T ₀₂ ) / 2− (τ ₃ + τ ₂ ) / 2 } Is required. After completing this operation, O, P, Q
Is fixed, it is only necessary to repeat the oscillations of (8) to (15).

Based on the distances between the stations thus obtained, the coordinates of the stations will be calculated. O to determine the coordinates
With (x ₀ , y ₀ , z ₀ ) as the origin, P (x ₁ , y ₁ , z ₁ ) is given. Now, assuming that x ₀ = y ₀ = z ₀ = ₀ , x ₁ , y ₁ , z ₁ is known, L ₀₁ = (x ₁ ² + y ₁ ² + z ₁ ² ) ^1/2 L ₀₂ = (x ₂ ² + y ₂ ² + z ₂ ² ) ^1/2 L ₀₃ = (x ₃ ² + y ₃ ² + z ₃ ² ) ^1/2 L ₁₂ = {(x ₂ −x ₁ ) ² + (y ₂ −y ₁ ) ² + (z ^{_{2 -z 1) 2} 1/2 L}} 23 = {(x 3 -x 2) 2 + (y 3 -y 2) 2 + (z 3 -z 2) 2} 1/2 L 13 = {(x ^{_{3 -x 1) 2 + (y}} 3 -y 1) 2 + (z 3 -z 1) 2} 1/2 from this _{x 1 x 2 + y 1 y} 2 + z 1 z 2 = (L 01 2 + L 02 2 -L ₁₂ ² ) / 2 x ₂ x ₃ + y ₂ y ₃ + z ₂ z ₃ = (L ₀₂ ² + L ₀₃ ² -L ₂₃ ² ) / 2 x ₁ x ₃ + y ₁ y ₃ + z ₁ z ₃ = (L _{01 ^{2 + L 03 2 -L 13 2}} ) / 2 further, with reference to FIG. _{3 X 1 (y 1 z 2} -y 2 z 1) + Y 1 (x 2 z 1 -x 1 z 2) + Z 1 (x 1 y ₂₋ x ₂ y ₁ ) = 0 X ₂ (y ₂ z ₃ −y ₃ z ₂ ) + Y ₂ (x ₃ z ₂ −x ₂ z ₃ ) + Z ₂ (x ₂ y ₃ −x ₃ y ₂ ) = 0 X ₃ (y ₁ z ₃ −y ₃ z ₁ ) + Y ₃ ( x ₃ z ₁ −x ₁ z ₃ ) + Z ₃ (x ₁ y ₃ −x ₃ y ₁ ) = 0 X _i ² + Y _i ² + Z _i ² = r _i ² (i = 1,2,3) _{x 2, y 2, z 2} , x 3, y 3, z 3, may be obtained. However, for simplicity of description, to the extent that without loss of generality to the following. Referring to FIG. 4, if x ₁ = L ₀₁ , y ₁ = 0, z ₁ = 0, z ₂ = 0, then x ₂ = (L ₀₁ ² + L ₀₂ ² −L ₁₂ ² ) / (2L _{01 ^{) x 3 = (L 01 2}} + L 03 2 -L 13 2) / (2L 01) y 2 = (L 01 2 -L 02 2 -L 12 2) / [2 {(2r 1 + L 01) (2r 1 -L ₀₁ )} ^1/2 ] where r ₁ = (L ₀₁ L ₁₂ L ₀₂ ) / [4 {S ₁ (S ₁ -L ₀₁ ) (S ₁ -L ₁₂ ) (S ₁ -L ₀₂ )} ^{_{1/2] S 1 = (L 01}} + L 12 + L 02) / 2 y 3 = {2L 01 2 (L 02 2 + L 03 2 -L 23 2) - (L 01 2 + L 02 2 -L 12 2) ( ^{_{L 01 2 + L 03 2 -L}} 13 2)} {(2r 1 + L 01) (2r 1 -L 01)} 1/2 / {2L 01 2 (L 01 2 -L 02 2 -L 12 2)} z ₃ = (L ₀₃ ² −x ₃ ² −y ₃ ² ) ^1/2 , and the coordinates are obtained.

Next, a specific example of the spread spectrum communication device used for distance measurement of the present invention will be shown. FIG. 5 shows a block diagram of distance measurement using a spread spectrum communication device. In the master station shown in the figure, a carrier wave sent from the carrier wave generator 2 is modulated by a modulator 3 with a code (code) made by a PN code (Pseudo random code) generator 1 to generate a modulated wave. .. The modulated wave passes through the duplexer 4,
It is transmitted from the antenna 5. At the same time, the operation of the PN code generator 1 is started and the time interval measuring device 11 is started to start measuring the time. On the other hand, the slave station receives the modulated wave from the master station as a radio wave. The received modulated wave passes through the transmission / reception switch 4 which is switched to the reception state, the local oscillation signal generated by the local oscillator 6 is mixed by the mixer 7, demodulated, and enters the matched filter 8. If the signal input to the matched filter 8 has the same sign as the matched filter pattern that it has, a pulsed signal is obtained from the output terminal of the matched filter 8 at the moment of matching. The waveform of this pulse is shaped by the waveform shaping circuit 9, and the control circuit 1
The PN code generator 1 is operated through 0. When the PN code generator 1 operates and generates a code, the antenna 5 oscillates a radio wave including a necessary code by the same operation as that of the master station. The partner station to which the slave station generates a radio wave and tries to transmit the code may be the master station or the slave station.

Here, if the received signal is not the code of the own station, no output appears in the matched filter 8 and the receiving station does not respond.

On the other hand, the master station receiving the response from the slave station passes the signal to the receiving side by the transmission / reception switch 4, demodulates it by the mixer 7 and the local oscillator 6, and then passes the demodulated signal to the matched filter 8. Therefore, after detecting that it is the code of its own station, the detected signal is shaped by the waveform shaping circuit 9, and then the time interval measuring device 11 is stopped. With this, it is possible to measure the time from when the master station transmits the radio wave to when the slave station responds and when the master station receives again. As already mentioned, since the individual times of the respective slave stations are known, it is possible to consider them and calculate the distance to the slave station. Similarly, the above operation is sequentially performed between the parent station and the child station.

The matched filter 8 is a well-known technique in the field of spread spectrum communication technique, but the concept of an example is briefly shown in FIG. 6A and 6C are plan views of the shaping filter 8. 6B is an input / output waveform of the filter of FIG. 6A, and FIGS. 6D and 6E are FIG.
It is an input / output waveform of the filter of (c). The figure is a schematic explanatory view. Actually, the number of comb-shaped electrodes and the like in FIGS. 6A and 6C is larger, and therefore the output waveform on the receiving side is also a pulse-like waveform that is sharper than the figure. Of course. With this method, the position of the unmanned air vehicle can be known.

[0023]

As described above, according to the present invention, absolute measurement and drift can be performed without using an expensive system such as an inertial navigation system using a gyro and an accelerometer for detecting the position of an unmanned air vehicle. Therefore, a simple and relatively accurate system can be provided.

[Brief description of drawings]

FIG. 1 is a diagram showing a state (coordinates) in which a spread spectrum communication device used for position detection of an unmanned aerial vehicle of the present invention is arranged, and an order of transmission / reception between the devices and types of codes.

FIG. 2 is a diagram when the types of codes are all different.
Figure corresponding to.

FIG. 3 is an auxiliary diagram for calculating the coordinates of each device (station) from the distance between each device (station).

FIG. 4 is a diagram showing an example for facilitating the explanation when obtaining the coordinates of a device (station).

FIG. 5 is a diagram showing an example of a configuration of distance measurement (transponder-like usage) by the spread spectrum communication device used in the present invention.

FIG. 6 is a conceptual diagram of a matched filter which is one of the constituent elements of FIG.

FIG. 7 is a diagram showing an outline of an inertial navigation device used in a conventional unmanned aerial vehicle (the same applies to manned vehicles).

Claims (1)

[Claims] 1. A position detecting device for an unmanned aerial vehicle by a distance measuring system using a spread spectrum communication technology,
A plurality of spread spectrum communication devices are arranged, one of the plurality of spread spectrum communication devices is assigned to a master station, the other is assigned to a slave station, and the spectrum spread communication device assigned to the slave station is One of them is mounted on the unmanned aerial vehicle, and instructions from the master station to the slave station are given in a transponder manner in a predetermined order for each code to measure the distance between all the spread spectrum communication devices, A position detecting device for an unmanned air vehicle, wherein coordinates of the unmanned air vehicle are calculated from the distance.