JP2005292058A - Method for determining tracking target angle of moving object and turntable using the same - Google Patents

Abstract

A turntable having a simple structure and an inexpensive human body automatic tracking function is obtained.
[Solution]
Paying attention to the fact that the trajectory with a constant distance difference between the two points is a hyperbola, and the target direction of the turntable coincides with an asymptote beyond a certain distance from the ultrasonic receiver, it was installed on the turntable side. The slope of the asymptote is obtained by detecting the difference in distance from the two points to the moving object with a pair of ultrasonic receivers. When there are a plurality of moving objects, the ultrasonic oscillation frequency is changed for each moving object. The ultrasonic wave is intermittently transmitted from the moving object side at a fixed period, and the ultrasonic receiver side detects the presence or absence of periodicity of the received wave. If the periodicity is lost, the moving object is considered to be stopped. .
[Selection] Figure 1

Description

  The present invention relates to a method for determining a tracking target angle of a moving object and a turntable using the same.

  Traditionally, floodlights for night work, surgical lighting, spotlights in theaters and banquet halls, etc., must be operated to follow the movements of users and actors, so rotation that can be changed by remote control or automatic tracking is possible. Used to install them on the pedestal.

  Speaking of a turntable capable of automatic tracking, there was no concept of calculating and calculating the distance and rotation angle before the development of microcomputer technology, but the sensor pair was swung to equalize the signal amount of the pair of sensors. The proposal was mainly.

  So far, Patent Document 1 and Patent Document 2 have proposed examples of a turntable having an automatic tracking function that introduces the concept of calculation and calculation of distance and rotation angle. In these devices, an ultrasonic transmitter is installed on a moving object, three or more ultrasonic receivers are installed on the ceiling or wall surface, and the absolute value of the distance between the moving object and three or more ultrasonic receivers. The position of the moving object is determined by measuring. In order to calculate the distance from the difference between the ultrasonic oscillation time and the reception time and the propagation speed of the ultrasonic wave, a means for notifying the receiver of the oscillation time is required. As this means, a radio wave transmitter / receiver is used in combination.

  Furthermore, in Patent Document 1, a large number of ultrasonic receivers are installed, and a moving object changes its position by selecting in order from the detection time having the smallest detection time or the detection energy having the largest energy. Describes a method for determining the position correctly without losing sight of the moving object even if the ultrasonic wave sending direction of the ultrasonic wave transmitter changes.

Japanese Patent No. 2746526

Japanese Examined Patent Publication No. 6-36323

However, in the above prior art,
1. Since a radio wave transmitter / receiver is used together as means for informing the receiver of the oscillation time, the configuration of the apparatus is complicated and expensive.
2. This tendency becomes more remarkable when there are a plurality of moving objects.
3. Since it is necessary to install a large number of ultrasonic receivers in order not to lose sight of the moving object, the configuration of the apparatus becomes complicated and expensive.
There were disadvantages such as.

  An object of the present invention is to eliminate the above-mentioned disadvantages of the prior art and to obtain a turntable that is simple and inexpensive.

The above purpose is
Pay attention to the fact that the trajectory having a constant distance difference from the point is a hyperbola, and that the target direction of the turntable coincides with the asymptote of the hyperbola at a distance of a certain distance or more from the pair of receivers. The tracking target angle is obtained by detecting the difference in distance from the two points to the moving object with a pair of receivers installed on the side.
2. When there are a plurality of moving objects, a feature for each moving object is given to the signal wave of the wireless oscillating means, and this feature is detected on the wireless receiving means side to identify the plurality of moving objects.
3. A signal wave is intermittently transmitted from the moving object side at a constant period, and the receiver side detects the presence or absence of periodicity of the received wave. If the periodicity is lost, the moving object is considered to be stopped.
Is achieved.

  According to the present invention, since a means for notifying an oscillation time such as a radio wave transmitter / receiver and a large number of ultrasonic receivers are not required, it is possible to obtain a turntable with a simple configuration and low cost.

An embodiment of a control method for a turntable of the present invention will be described with reference to FIGS.
The turntable 1 is attached to a pair of four ultrasonic receivers 3a, 3b, 3c, and 3d fixedly attached to a mount 22 and a horizontal turntable 8 and a horizontal turntable 8, and a reference point on the surface. It is composed of a vertical turntable 4 having 4a marking (⇒) and a power cord 2 for supplying power.

  The horizontal rotation table 8 includes a vertical rotation motor 5, a horizontal rotation motor 6, a rotation angle sensor 23 of the vertical rotation table 4, a rotation angle sensor 24 of the horizontal rotation table 8, and the ultrasonic receivers 3a to 3a. A control circuit 7 for controlling the rotation of the motor 5 and the motor 6 by comparing the tracking target angle calculated from the output of 3d and the outputs of the rotation angle sensors 23 and 24 is incorporated.

  An ultrasonic transmitter 51 is provided on the moving object 50, the turntable 1 is attached to the support base 9, the light 10 is attached to the vertical turntable 4, and the power supply of the light 10 is pulled from the power cord 2. The system is configured.

  FIG. 2 is a circuit diagram of the turntable 1. The power cord 2 is provided with a control circuit 7 for controlling the rotation of the motor 5 and the motor 6 by calculating the tracking target angle from the outputs of the light 10 and the ultrasonic receivers 3a to 3d. It is connected to the.

  In the control circuit 7, the outputs of the ultrasonic receivers 3 a to 3 d enter the comparators 41 a, 41 b, 41 c, 41 d having threshold values via the detection circuits 40 a, 40 b, 40 c, 40 d, and become pulse waveforms to the microcomputer 71. Entered.

  In the microcomputer 71, the time difference measurements 42 and 42 'are performed from the received waveforms of the paired ultrasonic receivers 3a, 3b and 3c and 3d, the distance difference calculation 43 and 43' is performed based on the time difference, and the distance difference and Target angle calculations 44 and 44 'are performed from the distance between the sound wave receivers 3a and 3b and the distances 3c and 3d.

  Connected to the motor drive circuits 45 and 45 ′ are a vertical rotation motor 5, a horizontal rotation motor 6, a rotation angle sensor 23 of the vertical rotation table 4, and a rotation angle sensor 24 of the horizontal rotation table 8. In accordance with the target angle calculated by the microcomputer 71 and the outputs of the rotation angle sensors 23 and 24, control is performed to rotate in the direction of the moving object or stop toward the direction of the moving object.

3 and 4 illustrate that the target tracking angle can be obtained with high accuracy from the difference in distance to the moving object 50 having the pair of left and right ultrasonic receivers 3a and 3b and the ultrasonic transmitter 51. FIG.
In FIG. 3, the positions of the pair of ultrasonic receivers 3a and 3b in the xy coordinates are (c, o) and (-c, o), and the distance between the ultrasonic transmitter 51 and the ultrasonic receivers 3a and 3b. 2a = distance difference 2a = constant locus becomes a hyperbola, and b = √ (c ² −a ² ), y = (b / a) √ (x ² −a ² ) Is done. The hyperbola has an asymptote and is expressed as y = (b / a) x.

  The position of the ultrasonic transmitter 51 in the xy coordinates is (X, Y), the coordinates of the asymptotic line y = (b / a) x and y = Y are (X ′, Y), and the xy coordinates When the origin (0, 0), that is, the angle formed by the midpoint of the pair of ultrasonic receivers 3a and 3b and the ultrasonic transmitter 51 is α and the slope of the asymptote is α ′, in the distance from the characteristics of the asymptote, α = α ′ X = X ′.

Here, ΔX = XX ′ and Δα = α−α ′ are calculated by actually substituting numerical values.
The calculation results are shown in FIG. As can be seen from FIG. 4, when the distance between the pair of ultrasonic receivers 3a and 3b is 0.5 m (c = 25 cm),
In the range of y> = 1 m, ΔX = X−X ′ = 0.015 m = 15 mm or less Δα = α−α ′ = 0.6 deg or less (see the arrow in FIG. 4).

Therefore, although it cannot be applied when the moving object is about ant (0.01 m above and below, 0.002 m left and right), the moving object is about the size of a human body (1.6 m above and below, 0.5 m left and right). In this case, sufficient tracking accuracy can be obtained only by measuring the distance difference without measuring the absolute value of the distance. That is, sufficient accuracy can be obtained even if means for knowing the oscillation time on the transmitter side is omitted.

  FIG. 5A shows the output signal waveform of the ultrasonic transmitter 51, the output waveforms of the detection circuits 40a and 40b of the signals input to the pair of left and right ultrasonic receivers 3a and 3b, and the output waveforms of the comparators 41a and 41b. It is. 5A, the ultrasonic oscillator 51 repeats intermittent oscillation with a period T = 60 msec and a duration T1 = 0.5 msec. Since a part of the oscillated ultrasonic wave is reflected on the wall or ceiling and becomes reverberant, the waveforms of the ultrasonic receivers 3a and 3b are tailed, and the influence appears on the detection output and the comparator output. This reverberation effect can be avoided by making the period T sufficiently long. After confirming the disappearance of reverberation, the time difference Td can be obtained by capturing the rising edge of the comparator output.

  FIG. 5B shows that there is a large obstacle between the ultrasonic transmitter 51 and the ultrasonic receivers 3a and 3b, or the ultrasonic transmitter 51 is deviated from the direction of the ultrasonic receivers 3a and 3b. This shows the case where the waveform is disturbed and the periodicity is lost and the period T cannot be confirmed. In such a case, the target angle is not calculated.

Next, the horizontal operation will be described with reference to the flowchart of FIG.
First, in order to confirm that the influence of reverberation has disappeared, a time T2 in which there is no signal in the left and right ultrasonic receivers 3a and 3b is measured (timer T2 reset → rising of the left and right comparators → T2 measurement). Next, T2 = 20 msec obtained experimentally and T2 are compared, and if T2> T3, it is determined that the effect of reverberation has disappeared. If T2 <= T3, it is determined that there is reverberation, and T2 is measured again.

  Since there may be no reverberation due to the disappearance of the signal, periodicity is confirmed. If T2 is larger than the oscillation period T = 60 msec (T2> = T), it is determined that there is no periodicity, and T2 is measured again. If T2 is smaller than the oscillation period T = 60 msec (T2 <T), it is determined that there is periodicity, and the time difference Td is measured.

  When the distance between the ultrasonic receivers 3a and 3b is 0.5 m, the maximum value of Td is 20 ° C. Td = 0.5 / 343.5 = 0.00146 seconds = 1.5 msec (Max) If there is no signal loss and periodicity, TdMax = 1.5 msec, so T4 = 1.5 msec. If Td <T4, it is determined that there is periodicity. If Td> = T4, it is determined that there is no periodicity, and T2 is measured again.

  Next, in measuring T2, it is determined whether the moving object is on the left or right side depending on whether the left side or the right side is received first. If the right side is ahead, the right side is determined, and if the left side is ahead, the left side is determined, and the right or left side data table is referred to. A target angle corresponding to the time difference Td is selected from the data table, and the target angle used in the motor drive circuit 45 is updated.

In the data table, the time difference of the rise of the comparator output is expressed as Td (seconds),
Distance of ultrasonic wave propagation velocity v = 331.5 + 0.6t m / msec (where t is the ambient temperature) 2a = Td (331.5 + 0.6t) m
And tracking target angle = gradient of asymptote tan α ′ = b / a = √ (c ² −a ² ) / a A list of numerical values of the target angle α ′ obtained from a.

  When the target angle is updated, the motor drive circuit 45 compares the output of the rotation angle sensor 24 of the horizontal turntable 8 with the target angle, and the horizontal direction so as to be positioned in the direction corresponding to the horizontal coordinate (X, Y). The motor 6 for rotation is rotated.

  In this way, if the received signal is not periodic, the target angle is not updated. If the received signal is periodic, the target angle is updated at a frequency of the period T, and the horizontal rotation motor 6 is tracked so as to track the moving object. Rotates. If the moving object stops, it stops at the position where the horizontal turntable 8 reaches the target direction.

  When there are a plurality of moving objects, a feature for each moving object is given to the signal wave of the wireless oscillating means, and this feature is detected on the wireless receiving means side to identify the plurality of moving objects. For example, in FIGS. 5A and 5B, the frequency of the ultrasonic wave is f1 = 40 kHz, but when there are a plurality of moving objects, f1 = 40 kHz, f2 = 50 kHz, f3 = 60 kHz. . . The receiving side may adopt a detection method corresponding to this. Since the same applies to the vertical direction, description of the vertical direction is omitted.

  As described above, according to the present invention, since the tracking target angle can be accurately measured from the difference in distance without measuring the absolute value of the distance, there is no need for means for notifying the oscillation time on the transmitter side such as a radio wave transmitter / receiver. Become. In addition, when there are a plurality of moving objects, the oscillation frequency may be changed for each moving object, so that a means for notifying the oscillation time such as a radio wave transmitter / receiver is not necessary.

Further, when there is an obstacle or the like and the received signal is disturbed, the update of the tracking target angle is postponed until the received signal is no longer disturbed, so that it is not necessary to search for a moving body by a large number of ultrasonic receivers.

The perspective view which shows one Embodiment of this invention. The circuit diagram which shows one Embodiment of this invention. Explanatory drawing of a measurement principle. Error comparison diagram. Timing chart. Timing chart. flowchart.

Explanation of symbols

3a, 3b, 3c and 3d are ultrasonic receivers, 51 is an ultrasonic transmitter, 4 is a vertical turntable, 7 is a control circuit, 8 is a horizontal turntable, and 9 is a support stand.

Claims (7)

A wireless oscillating means is installed on a moving object, and a transmission signal from the wireless oscillating means is received by a wireless receiving means arranged in a pair. A distance difference between the wireless receiving means and the moving object is 2a. When the tracking target angle is α and the distance between the wireless receiving means is 2c, the correlation between the distance difference 2a, the tracking target angle α, and the distance 2c between the wireless receiving means is calculated or measured in advance as appropriate. The result obtained by the method is stored in a storage device, and the tracking target angle is determined by comparing the calculation result of the distance difference 2a in the tracking process of the moving object with the content of the storage device. To determine the tracking target angle of a moving object. A wireless oscillating means is installed on a moving object, a transmission signal of the wireless oscillating means is received by a wireless receiving means arranged in a pair, a difference in distance between the wireless receiving means and the moving object is calculated, and this is expressed as 2a. The angle formed by the straight line connecting the wireless receiving means and the straight line connecting the midpoint of the pair of wireless receiving means and the wireless oscillating means installed on the moving object, that is, the tracking target angle of the moving object is α, and between the wireless receiving means A method of determining a tracking target angle of a moving object, characterized in that when the distance is 2c and b = √ (c ² −a ² ), the tracking target angle α is approximately calculated from the relational expression tan α = b / a. A turntable comprising a turntable in the horizontal direction and / or vertical direction, a support for this turntable, wireless oscillation means installed on a moving object, a plurality of wireless receivers mounted on the support for the turntable or in the vicinity of the turntable Means, a turntable having a moving object tracking function comprising a control circuit that performs control such that the reference point of the turntable is rotated in the direction of the moving object at the output of the wireless receiving means,
The wireless receiving means are arranged in a pair in a horizontal direction and / or a vertical direction, and the tracking target angle in the horizontal direction and / or the vertical direction of the turntable is determined by the method according to claim 1 or 2. Features a turntable. 4. The turntable according to claim 3, wherein the wireless oscillating means and the wireless receiving means are an ultrasonic transmitter and an ultrasonic receiver, respectively. 5. The turntable according to claim 3, wherein the correlation is stored, the distance is calculated, the tracking target angle is calculated, or the stored contents are compared with the distance using a microcomputer. A signal wave is intermittently transmitted from the wireless oscillating means, and the presence or absence of periodicity of the received wave is detected on the wireless receiving means side, and if the periodicity cannot be detected, the moving object is considered to be stopped. The turntable according to any one of claims 3 to 5, wherein the tracking target angle is not updated. 4. When there are a plurality of moving objects, a feature for each moving object is added to the signal wave of the wireless oscillating means, and the feature is detected on the wireless receiving means side to identify the plurality of moving objects. The turntable according to any one of 6.

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