JPS5999308A - Distance measuring sensor - Google Patents

Abstract

PURPOSE:To obtain a distance measuring sensor, which is mounted on an unmanned conveying robot and can measure the distance accurately regardless of the reflecting characteristics of a body to be measured, by using laser beams. CONSTITUTION:A laser beam is projected from a laser device 1 through a rotary mirror 3 and rotated at an equal angle speed omega. When the spots of the laser beams are projected on positions C and D on a floor 2, the spots are received by light receiving devices 4 and 6 through a condenser lens 5. A counter 8 counts clock pulses CLK based on the output pulses from the light receiving device 4. The counter 8 become inoperative by the output pulse signal from the light receiving device 6. A latch circuit 9 latches the counted value of the counter 8, and outputs the value to an operating circuit 10. The counted value indicates a time (t) from the time point when the light receiving device 4 receives the spot to the time point when the light receiving device 6 receives the spot. When a body 12 is located at a position E, the light receiving device 6 receives the spot of a position F. By measuring the time (t), the distance (l) of the body 12 can be obtained by the expression in the Figure.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a distance measuring sensor that uses a laser beam, and in particular, when an unmanned guided robot moves in a factory, it detects an unspecified object placed on the floor and moves to the object. The present invention relates to a distance measuring sensor that is effective in measuring distance.

Conventionally, there are distance measuring sensors mounted on unmanned guided robots that utilize ultrasonic waves. This distance sensor measures the time from when an ultrasonic wave is emitted until it receives the reflected wave of the ultrasonic wave from the object to be measured, and measures the distance to the object based on this time and the speed of sound. , the measurement accuracy largely depended on the reflection characteristics of the object.

An object of the present invention is to improve this point by using a laser beam, and to provide a distance measuring sensor that can accurately measure distance with a simple configuration.

According to this invention, the laser beam projector installed at a predetermined height from the floor emits a laser beam at a constant angular velocity so that the laser beam surface is perpendicular to the floor surface, and emits the laser beam from a reference position. A light receiver is provided that captures the laser beam on an optical path connecting the light receiver and a point on the floor surface that is similar to a predetermined distance apart, and the laser beam is located on the optical path based on the capture time of the laser beam from a predetermined time of the light receiver. I am trying to calculate the distance of an object.

The present invention will now be described in detail with reference to the accompanying drawings.

FIG. 1 is a block diagram showing an embodiment of a distance measuring sensor according to the present invention. In FIG. 1, a laser beam emitted from a laser 1 is rotated and projected at a constant angular velocity ω by a rotating mirror 3 provided at a predetermined height h2 from a floor surface 2. Note that the rotating mirror 3 rotates and projects the laser beam so that the rotating laser beam plane thus formed is orthogonal to the floor surface 2.

When the spot of the laser beam irradiates a position C on the floor surface 2 (at a distance A from the projection position of the rotary mirror 30 on the floor surface 2), the light receiver 4 focuses this spot on a condenser lens 5.
Receives light through the sensor and outputs a pulse signal. Similarly, the light receiver 6 detects the spot of the laser beam at the position (
When the rotary mirror 30 is irradiated at a position (distance 12) D from the projection position on the floor surface 2, this spot is received through the E5 element lens 5 and a pulse signal is output. Note that the condenser lens 5 is provided at a predetermined height hl from the floor surface 2.

The pulse signal output from the light receiver 4 is applied to the set terminal S of the flip-flop 7, and is also applied to the counter 8.
is applied to the reset terminal R of , and sets and resets the flip-flop 7 and counter 8, respectively. When the flip 70 knob 7 is set, it outputs the signal "]" from its output terminal Q to the enable terminal EN of the counter 8, making the counter 8 operational. Clocks
- Counts the pulses CLK and outputs the counted value to the latch circuit 9.

On the other hand, the pulse signal output from the light receiver 6 is applied to the reset terminal R of the flip 70 knob 7 and is also applied to the load terminal LD of the latch circuit 9. As a result, the flip-flop 7 is set, and its output terminal Q
The latch circuit 9 latches the output value (count value) of the counter 8 and outputs it to the arithmetic circuit 10. Note that the count value latched by the latch circuit 9 indicates the time t from when the light receiver 4 receives the laser beam spot until the light receiver 6 receives the laser beam spot.

The arithmetic circuit 10 calculates the data corresponding to the time t and a constant preset in the constant setter 11, that is, distance'.
1 + '2's height hl, h2 and angular velocity ω
The distance of the object existing between distances 11 and 12 is calculated by performing calculations to be described later based on data corresponding to .

Next, the calculations executed by the calculation circuit 10 will be explained with reference to FIG.

In FIG. 2, the rotation center position B of the laser beam and the position f! of the condenser lens 5 with the floor surface 2 as the X axis! With LA on the y-axis, lower the object 12 so that its front surface is at position E on X@. At this time, the light receiver 4 can receive the laser beam spot when it is on the gland AC, and the light receiver 6 can receive the laser beam spot when the spot is on the line AD. Therefore, when the object 12 is located at the position shown in FIG. 2, the light receiver 6 receives the laser beam spot when the spot is at the position PK in front of the object 12.

Now /ACO=ψ1. Line segment FE=h3/FBc-ω
1 (1 is the time required for the laser beam to reach from BC to BF) / BGO = ψ (G is the time X on the extension of line BF)
Position on the axis) Line segment - d = 1 = l' Line segment 0E = Jl' (distance to be measured) According to the geometric relationship, b1 knee hs = #2: (72-l) h2 : h3=/' : (C-11) Simple ψ==1
12/, /' 1ψx=ht/A! 1 ωt+ψ=ψl is obtained. When l is determined from the above formula, the following formula is obtained. In the above equation ( ), everything except time is a constant, so the distance l to the object 12 can be determined by measuring the time t.

The calculation circuit 10 (FIG. 1) calculates the distance l of the object by executing the calculation of the above equation (1).

In addition, the constant 1. Instead of , using the constant ψl, the (1)
Expressing the formula, it becomes. Further, if there is no object between the distance l□ and 12, ωt=/cBD, and in this case, the arithmetic circuit 10 will output the distance 12.

As explained above, according to the present invention, since a laser beam is used, the distance to the object can be accurately measured regardless of the reflection characteristics of the object. Furthermore, when the offshore distance sensor according to the present invention is mounted on an unmanned guided robot,
It can be used as a visual means with a field of view ranging from distances 11 to 12.

Note that when measuring the distance of an object using this distance measurement sensor, the distance 1. It is necessary to make sure that there are no objects blocking the laser beam. Furthermore, although two photoreceivers were provided in this embodiment, the present invention can be implemented with one photoreceiver if the time is measured based on an appropriate timing synchronized with the rotation period of the laser beam. be.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing an embodiment of a distance measuring sensor according to the present invention, and FIG. 2 is a geometric diagram used to explain the present invention in detail. 1...Laser, 2...Floor surface, 3...Rotating mirror,
4゜6... Light receiver, 5... Condensing lens, 7... Free lag flop, 8... Counter, 9... Latch circuit, 10... Arithmetic circuit, 11... Constant Setting device, 12
···object.

Claims (1)

[Claims] a laser beam projector that rotates and projects a laser beam at a constant angular velocity so that the laser beam plane is orthogonal to the floor;
a light receiver that captures a laser beam reflected from a distance-measuring object on an optical path connecting the light receiver and a point on the floor spaced a predetermined distance from a reference position; A measuring device comprising: a timer for measuring the time until the laser beam is captured by the light receiver; and an arithmetic circuit for calculating the distance of the object to be measured from a reference position based on the time measured by the timer. distance sensor.