JPH0650732Y2 - Variable illumination distance measuring device with spatial filter - Google Patents

Description

[Detailed Description of the Device] A. Industrial Application Field The present invention relates to a distance measuring device using a spatial filter.
The illumination is variable to improve the measurement accuracy.

B. Outline of the device In a distance measuring device using a spatial filter, if the amount of light reflected from the road surface is insufficient or too large, it may not be detected by the photodetection converter, or the detection output may be saturated. . Therefore, we installed a lighting device on the vehicle body,
The distance measurement accuracy is improved by adjusting the amount of illumination light so that the absolute value of the vector in the phase space becomes substantially constant.

C. Conventional technology Conventionally, in automatic driving of unmanned guided vehicles, a method of laying electromagnetic induction wires and optical reflective tape on the road to form a running guide, and mounting encoders and tacho-generators on axles and measuring wheels Then, there is a method of measuring the speed and moving distance of the unmanned vehicle from a pulse or analog voltage corresponding to the rotation of the wheel.

However, these methods require processing of a traveling path by laying a guide wire, a reflective tape, etc. on the road surface, and the processing work is troublesome, and the wheel slippage due to external force etc. I couldn't make good measurements.

For this reason, a distance measuring method using a spatial filter has been developed as a method of measuring a moving distance in a non-contact manner without requiring guidance from the outside.

A distance measuring device using this spatial filter is shown in FIG.
This will be described with reference to FIG.

As shown in FIGS. 5 and 6, the reflected light from the road surface 1 is captured by the optical system 2, and the line sensor (CCD) 3
Thus, it is sampled at a predetermined cycle and converted into an electric signal. Here, although the reflected light from the road surface 1 is composed of a combination of various kinds of frequencies,
If the materials and surrounding environment are constant, the combination is considered to be almost constant. If the optical system 2, the line sensor 3 and the like are provided on the bottom surface of the vehicle (not shown), slight fluctuations will be repeated as the vehicle travels.

The output from the line sensor 3 passes through the read circuit 4 and then
It is input to the spatial filter calculation unit 5. The spatial filter calculation unit 5 extracts an arbitrary frequency component from the reflected light composed of optically random frequencies, and obtains a vector corresponding to the moving distance in the phase space from the time series change thereof. . That is, the signal P that has passed through the read circuit 4 is converted into a digital signal by the A / D converter 6, but when expanded into a Fourier series, it becomes as follows.

However, x _o is the position of the vehicle at time t, x is the position in the line sensor read from the read circuit, and k = 2π / L, i = 0,1,2 ..., L with reference to x _o Is the measurement range of the line sensor.

The Fourier coefficients A _i (x _o ) and B _i (x _o ) are given by the following equation.

A _i (x _o ) ＝ (2 / L) ・ ▲ ∫ ^L ₀ ▼ P ・ cos (k ・ i ・ x) dx
… (2) B _i (x _o ) ＝ (2 / L) ・ ▲ ∫ ^L ₀ ▼ P ・ sin (k ・ i ・ x) dx
(3) These signals P are each multiplied by a cosine wave and sine waves S ₁ and S ₂ of a specific frequency shown in the following equations as spatial filters, and integrated in a predetermined range.

_{S 1 = F · cos (n} · k · x) ... (4) S 2 = F · sin (n · k · x) ... (5) a (x o) = ▲ ∫ L 0 ▼ P · S 2 d _x = F · B _n (x _o ) · L / 2…
(6) b (x _o ) = ▲ ∫ ^L ₀ ▼ P ・ S ₁ d _x ＝ F ・ A _n (x _o ) ・ L / 2…
(7) Here, if the output P from the line sensor is due to reflected light having a constant condition such as a road surface or environment, a certain nth-order component should change continuously in a triangular function. Yes, for example, as shown in the following formula.

P _n (l) = G · sin (n · k · l + φ) (8) Therefore, the n-th order Fourier coefficients A _n and B _n are obtained as follows.

A _n (x _o ) ＝ (2 / L) ・ ▲ ∫ ^L ₀ ▼ P _n (x _o + x) ・ cos (k ・
n · x) dx = 2 / L ▲ ∫ ^L ₀ ▼ Gsin {n ・ k (x _o + x) + φ} ・ cos (k
・ N ・ x) dx = G / L ▲ ∫ ^L ₀ ▼ sin {2nkx ＋ nkx _o ＋ φ} ＋ sin (nkx _o ＋
φ) dx = G / L ・ L ・ sin (nkx _o + φ) = G ・ sin (nkx _o + φ) (9) Similarly, B _n (x _o ) = G ・ cos (nkx _o + φ) (10) (9) ) Substituting equation (10) into equations (6) and (7) and rearranging gives the following equation.

a (x _o ) = (FL / 2) ・ Gcos (nk ・ x _o + φ) (11) b (x _o ) = (FL / 2) ・ Gsin (nk ・ x _o + φ) (12) A (x _o ), b (x _o ) obtained in step (3) vibrate in a trigonometric function, and are then input to the moving distance calculation unit 7.

Here, the moving distance calculation unit 7 determines the rotation angle ρ about the origin on the phase plane shown in FIG. 8 of the vector A whose two-dimensional coordinates are a (x _o ), b (x _o ). Ask. That is, as shown in FIG. 8, a vector A having two-dimensional coordinates of a (x _o ) and b (x _o ) rotates at a rotation angle nkx _o proportional to the movement distance x _o . Therefore, the following relational expression holds from FIG.

nkx _o + φ = 2πm + ρ (13) where m is the number of revolutions around the origin, ρ = arctan (b (x _o ) / a (x _o )), (0 ≦ ρ ≦ 2π) φ is the initial value ρ _{t = o} .

Therefore, if the equation (13) is modified, the moving distance x _{o to be obtained} is given by the following equation.

x _o = m · p + (ρ−φ) p / 2π (14) Incidentally, in FIG. 5, the CPU 18, RAM 19, and ROM 20 constitute the spatial filter calculation unit 5 and the moving distance calculation unit. Further, the moving distance x _o is time-differentiated by the moving speed calculator 17 to obtain the speed.

D. Problem to be Solved by the Invention However, in the above-mentioned conventional method, since the reflected light from the road surface is detected by the line sensor 3, it becomes impossible to detect in a place where the reflected light is insufficient or excessive, The detection output will be saturated. Further, even if the reflected light is not insufficient to become undetectable, if it is insufficient, the absolute value of the vector in the phase space shown in FIG. 8 becomes small,
The rotation around the origin could not be detected accurately.

The present invention has been made in view of the above conventional technology,
An object of the present invention is to provide a variable illumination distance measuring device using a spatial filter that can variably illuminate a road surface and obtain appropriate reflected light to maintain the absolute value of a vector in a phase space substantially constant.

E. Means and actions for solving the problem The rotation angle about the origin of the vector in the phase space is proportional to the moving distance of the vehicle body, but its absolute value is proportional to the amount of reflected light. It is a thing. Therefore, if the amount of reflected light is insufficient, the absolute value of the vector becomes small, and conversely, if the amount of reflected light becomes excessive, the absolute value of the vector becomes large.

Therefore, an illuminating device is provided on the vehicle body to increase the light quantity when the vector's absolute value becomes small, and conversely, when the vector's absolute value becomes large, decrease the vector's absolute value to reduce the vector's absolute value. It will be kept almost constant.

F. Embodiment Hereinafter, one embodiment of the present invention will be described in detail with reference to the drawings.

1 to 3 show one embodiment of the present invention. As shown in FIG. 1, in this embodiment, a lighting device 8, a control circuit 9 and an amplitude calculator 10 are added to the distance measuring device shown in FIGS. 5 and 6. Here, the amplitude calculator 10 calculates the absolute value of the vector A in the phase space shown in FIG. 8 based on the signals a (x _o ), b (x _o ) from the spatial filter calculator 5, To calculate.

This absolute value | A | is input to the control circuit 9. Here, the control circuit 9 is for adjusting the amount of light of the illumination device 8, and specifically uses a triangular wave generation circuit as shown in FIG. That is, in the triangular wave generating circuit of the control circuit 9, an operational amplifier A ₁ is Schmitt circuit, an operational amplifier A ₂ has respectively an integrating circuit, when powered on, the operational amplifier A ₁
A square wave is output as the output of the above, and this is integrated by the operational amplifier A ₂ to form a triangular wave V ₁ shown in FIGS. 4 (a) and 4 (b). This triangular wave V ₁ is input to the operational amplifier A ₃ and D /
Absolute value of vector digitalized by A converter |
A | is also input to this operational amplifier A ₃ . The operational amplifier A ₃ is
The triangular wave V ₁ is compared with the vector absolute value | A |, and a square wave V ₂ that is turned on when the triangular wave V ₁ exceeds the vector absolute value | A | and turned off when it falls below is output To do. Here, as shown in FIGS. 4A and 4B, the square wave V ₂ has a coarser density as the absolute value | A | of the vector becomes larger, and becomes denser as it becomes smaller. This square wave V ₂ is input to the lighting device 8. In the illumination device 8, by switching action transistor Tr is based on a square wave V _2, and outputs a square wave V ₃ corresponding to the square wave V _2. This square wave V ₃ is input to the lamp L,
The lamp L illuminates the road surface with a quantity of light according to the density of the square wave V ₃ . The lamp L may be supported so as to be suspended in front of the vehicle body 12 as shown in FIG. 3, for example, so that the reflected light of the road surface is effectively incident on the optical system 2.

Therefore, in the present embodiment having the above configuration, the control circuit 9 adjusts the light amount of the lighting device 8 as follows. For example, when the amount of light incident on the optical system 2 is insufficient, the size of the signal P sampled by the line sensor 3 at a predetermined cycle and converted into a digital signal by the A / D converter 6 becomes small,
Therefore, in the spatial filter calculation unit 5, the above equation (1)
The _{values of} a (x _o ) and b (x _o ) calculated according to the equation (7) are also small. As a result, the absolute value of the vector A in the phase space obtained by the amplitude calculator 10 also becomes small, and as shown in FIG. 4 (a), the operational amplifier A ₃ of the control device 8 compares it with the triangular wave V _1. And a square wave V ₂ with a relatively high density
Due to the switching action of Tr, the corresponding square wave V ₃
Therefore, the light amount of the lamp L is increased.

On the other hand, when the amount of light incident on the optical system 2 is excessive, the above is reversed, and the absolute value of the vector A in the phase space obtained by the amplitude calculator 10 becomes large. Therefore, Fig. 4 (b)
When compared with the triangular wave V ₁ by the operational amplifier A ₃ of the control circuit 8 as shown in, less dense square wave V ₂ becomes, by the switching action of the transistor T _r, the square wave V ₃ corresponding thereto Therefore, the light amount of the lamp L is reduced.

That is, when the quantity of the reflected light entering the optical system 2 is insufficient, the quantity of the light of the lamp L is increased, and conversely, when the quantity of the reflected light entering the optical system is excessive, the quantity of the lamp L is decreased. As a result, the absolute value of the vector in the phase space becomes almost constant, and the rotation angle about the origin of this vector can be accurately obtained.

Although the triangular wave generating circuit is used as the control circuit 19 in the above embodiment, the present invention is not limited to this. Further, the absolute value of the vector in the phase space is allowed to increase or decrease within a range in which the angle detection is reliable.

G. Effect of the Invention As described above in detail with reference to the embodiments, the present invention attaches the illumination device to the vehicle body and adjusts the illumination light amount so that the vector in the phase space is substantially constant. Always reliable distance measurement.

[Brief description of drawings]

FIG. 1 is a block diagram showing an embodiment of the present invention, FIG. 2 is a circuit diagram showing a lighting device and a control circuit, FIG. 3 is an external view of a vehicle body to which a lamp is attached, and FIG. 4 (a) ( b) are each a graph showing the output waveform of the operational amplifier a _1, a ₂ and transistor T _r, Fig. 5 is a configuration diagram of a conventional moving distance measuring apparatus, FIG. 6 is a block diagram of the apparatus, Fig. 7 Is a graph showing a conventional spatial filter, and FIG. 8 is an explanatory view showing vectors and their rotation angles in the phase plane. In the drawings, 1 is a road surface, 2 is an optical system, 3 is a line sensor, 4 is a readout circuit, 6 is an A / D converter, 7 is a movement distance calculator, 8 is a lighting device, 9 is a control circuit, and 10 is an amplitude. Calculation unit, 11 is a D / A converter, 12 is a vehicle body, 17 is a moving speed calculator, 18 is a CPU, 19 is RAM, 20 is ROM, A ₁ and A ₂ are operational amplifiers, and _Tr is a transistor.

Claims (1)

[Scope of utility model registration request] 1. A light detecting and converting unit which is arranged downward on a vehicle body and which captures light reflected on a traveling road surface, samples the light at a predetermined cycle and converts it into an electric signal, and an electric signal from the light detecting and converting unit. , A spatial filter calculation unit for extracting an arbitrary frequency component by multiplying by a sine wave and a cosine wave and integrating it within a predetermined range, and obtaining a sine wave signal and a cosine wave signal oscillating at the frequency, and the spatial filter And a traveling distance calculation unit for calculating a moving distance of the vehicle body from a rotation angle centered on an origin in a phase plane of a vector having two-dimensional coordinates of a sine wave signal and a cosine wave signal obtained by the calculation unit. In a distance measuring device using a spatial filter, an illuminating device that illuminates a traveling road surface is provided on the vehicle body, and an electric circuit that controls the light amount by the illuminating device so that the absolute value of the vector is substantially constant. Variable illumination range finder according to a spatial filter, characterized in that digit.