JPH06137867A - Scan position detecting device and scan position control device for distance measuring device - Google Patents

Abstract

PURPOSE:To detect the scan angle position with a high resolution. CONSTITUTION:A two-sided reflection type rotating mirror 14 is rotated by a motor 15 in a range of a required angle. The distance measuring light of a distance measuring laser diode 11 is reflected by a fixed mirror 13, and furthermore, reflected by the rotating mirror 14 to go outside. The reflected light from an object is received by a light receiving means 31. Distance to the object is measured on the basis of the time from the emission of the distance measuring light to the receiving of the reflected light. The detecting light, which goes out from a scan position detecting laser diode 21, is reflected by the rotating mirror 14, and enters a position detecting element (PSD) 22. The position signal showing the incidence position is output from the position detecting element 22. Scan angle position of the distance measuring light to be scanned by the rotating mirror 14 is displayed by the position signal of the position detecting element 22. Feedback control of the motor 15 is performed by using this position signal.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention projects a distance measuring light and measures the distance to the object based on the reflected light from the object, and more particularly, the projection direction of the distance measuring light within a certain angle range. The present invention relates to a scan position detection device and a scan position control device used in a distance measuring device of a type that scans with a scanner.

[0002]

2. Description of the Related Art There are the following types of scan position detecting devices or scan position control devices in a distance measuring device, but each has a problem.

An apparatus for detecting the rotational angle position of a motor for rotating a mirror for scanning the distance measuring light by using an encoder or a plurality of photodiodes has a low positional resolution.

In a device for controlling a scan motor by an open loop control system, it is easily affected by disturbance such as vibration and shock, and scanning performance is deteriorated. It is very vulnerable to disturbances because it does not have a compensation circuit.

In the device for controlling the scan motor by the closed loop control system, the correction is performed by the deviation between the target value and the current value. However, since the position detecting device having the low scan position resolution is used as described above, the correction is performed. Linearity is not good.

[0006]

DISCLOSURE OF THE INVENTION The present invention provides a position detecting device capable of accurately detecting a scan position.

The present invention also provides a scan position control device which is strong against disturbance and has high linearity based on accurate scan position detection.

A scanning position detecting device in a distance measuring device according to the present invention is a distance measuring light source for generating a distance measuring light, a detecting light source for generating a scanning position detecting light, and a distance measuring light for reflecting the distance measuring light. Is arranged at a position where the detection light reflected by the rotary mirror is incident on the rotary mirror that reflects the detection light and emits light to the outside. Is provided with a position detection element that outputs a position signal indicating the incident position.

The light source for distance measurement included in the distance measuring device can be omitted to represent the scan position detecting device alone.

That is, the scan position detecting device according to the present invention reflects the detection light in a region other than the region used for reflecting the detection light source for generating the scan position detection light and the distance measurement light. A rotating mirror, and a position detecting element arranged at a position where the detecting light reflected by the rotating mirror is incident in a rotation angle range of the rotating mirror and outputting a position signal indicating an incident position of the detecting light. ing.

The scan position control device according to the present invention using the above-mentioned scan position detection device is a region other than the region used for reflecting the detection light source for generating the scan position detection light and the distance measurement light. At a rotation mirror that reflects the detection light, and at a position where the detection light reflected by the rotation mirror is incident in the rotation angle range of the rotation mirror, a position signal that indicates the incident position of the detection light is generated. Position detection element for output, scan motor for rotating the rotating mirror, scan for the above
A target value command device that gives a target value of the motor at fixed time intervals, and a target value given from the target value command device and a position signal output from the position detection element are input, and the position of the scan motor is A motor controller for controlling the scan motor so as to match the target value is provided.

The light source for detection can also be used as the light source for distance measurement. Further, the rotating mirror may be a double-sided mirror whose both surfaces are mirror surfaces that reflect light, or a single-sided mirror whose only one surface is a mirror surface. In the case of a double-sided mirror, one surface would be used to reflect the distance measuring light and the other surface to reflect the scan position detecting light. In the case of a single-sided mirror, the distance measuring light may be reflected on a part of the mirror surface and the scan position detecting light may be reflected on the other part.

According to the scan position detecting device of the present invention, the position detecting element (PSD = Position Sensitive Dev
ice) is used to detect the scan position. The output position signal of the position detecting element is an analog signal and represents the incident position of light with high accuracy. Therefore, according to the present invention, a high position (angular position) detection resolution can be obtained.

Further, according to the present invention, the distance measuring light emitted to the outside and the light for position detection are reflected by one rotating mirror. Therefore, the reflection direction of the position detection light correctly corresponds to the emission light direction of the distance measurement light, and no error occurs in this portion. In addition, the configuration is very simple, and fine adjustment of the rotating mirror is unnecessary.

In the position control device according to the present invention, since the closed-loop control system is constructed by using the position signal obtained from the above-mentioned position detecting element, the correction operation is performed even if there is a disturbance such as vibration or shock. So it is strong against external disturbances. Moreover, since the closed-loop control system is constructed using the output signal of the high-resolution position detection element, the scanning linearity is high.

[0016]

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 shows the arrangement of optical systems of a distance measuring device and a scan position detecting device.

Laser diode 11 for generating distance measuring light
And a laser diode 21 for generating scan position detection light.

The distance measuring light emitted from the laser diode 11 is collimated by the projection lens system 12, reflected by the fixed mirror 13 and directed to the rotary mirror 14.

The rotating mirror 14 is a double-sided mirror whose both sides are reflecting mirrors, and is reciprocally rotated within a predetermined angle range by a scan motor 15. The scan motor 15 is, for example, a voice coil motor. The rotation position of the motor 15 is a rotating mirror, either directly or via an appropriate reduction mechanism.
Transmitted to 14.

The distance measuring light reflected by the fixed mirror 13 is reflected by one surface of the rotating mirror 14 and projected to the outside. If necessary, a lens system 16 for collimating or condensing the light reflected by the rotating mirror 14 may be provided.

The distance measuring light projected toward the outside is reflected by the detection target, if any, and a part of it returns. A light receiving optical system is provided in the vicinity of the above projection optical system, and this light receiving optical system includes a light receiving lens system 32 and a light receiving element 31 (photodiode or phototransistor). The light reflected from the object is the lens system 32
The light is collected by and enters the light receiving element 31.

As will be described later, the laser diode 11
From this, pulsed light for distance measurement is generated. Therefore, the light reflected from the object and received by the light receiving element 31 is also pulsed light. The distance to the object is measured from the time when the projected pulse light is generated to the time when the reflected pulse light is received,
It is calculated based on this clocked time.

Laser diode 21 for scan position detection
The scanning position detection light from is also pulsed light and is emitted at the same time as the distance measurement light of the laser diode 11. The detection light is reflected by the other surface of the rotating mirror 14 and enters the position detection element (PSD) 22. The position detecting element 22 outputs a signal indicating the incident position of incident light. If necessary, the detection light of the laser diode 21 is also collimated or condensed by the lens system 23.

When the rotary mirror 14 rotates, the projection direction of the distance measuring light reflected and emitted from one surface of the rotary mirror 14 is scanned. The detection light is also the same rotating mirror 14
Since the light is reflected by the other surface and enters the position detecting element 22, the light receiving surface of the position detecting element 22 is scanned. Since the distance measuring light and the detecting light are both reflected by the single rotating mirror 14, the incident position of the detecting light on the position detecting element 22 correctly represents the projection direction of the distance measuring light. .

FIG. 2 shows an example of changes in the scan angle of the distance measuring light. The scan angle is equal to the rotation angle of the rotating mirror 14. In this example, one scan is performed in 100 ms. The scan angle range is 100mrad. The motor 15 or rotating mirror 14 will make one round trip in the range of 100 mrad in 200 ms. As shown below, the distance measurement is performed 1000 times in 100 ms.

FIG. 3 shows the timing of the distance measuring light, the received light (reflected light from the object to be treated) and the detection light.

The distance measuring light has a pulse width of 50 ns and is 100
It emits light in a cycle of μs. The received light enters the light receiving element 31 slightly after the generation of the distance measuring light. If the maximum distance to be measured is 250 m, the maximum delay of the received light with respect to the distance measuring light is about 1.7 μs.

The detection light also has a pulse width of 50 ns and has a width of 25 μm.
Light is emitted in a cycle of s. The generation timing of the distance measuring light and the generation timing of one of the four detection light beams are completely the same. As will be described later, the target value of the motor 15 is given at the generation timing of the distance measuring light.

FIG. 4 shows the electrical construction of the scan position controller.

The distance measuring CPU 41, as shown in FIG.
The target value (angular position and speed) is output every 100 μs and given to the motor control device 42 (step 51). This target value is preferably precalculated and stored in memory. As described above, the laser diodes 11 and 21 are controlled to emit light in synchronization with the output time of the target value. After that, the distance measurement CPU 41 measures the time until the reflected light is received and calculates the distance based on the measured time (step 52). In this distance measuring process, the position signal obtained from the position detecting element 22 is also used to determine the direction in which the object exists (and the shape of the object).

The motor controller 42, as described above,
A signal representing the angular position measured by the position detecting element 22 is input every 25 μs. This position signal is held for 25 μs. Since the output signal of the position detection element 22 and the angular position of the rotary mirror 14 (motor) are not necessarily proportional, it goes without saying that an appropriate conversion calculation (including conversion by a table) is performed between them.

The motor control device 42 calculates a position change amount (speed) based on the position signal provided from the position detection element 22. Then, the deviation (positional deviation) between the target position given from the CPU 41 and the actual position measured by the position detection element 22 is obtained, and the target speed given from the CPU 41 and the actual velocity found from the measured actual position are calculated. The deviation (speed deviation) is calculated, the manipulated variable is determined so that these position deviation and speed deviation are close to zero, and given to the motor 15,
A so-called feedback (closed loop) control of the motor 15 is performed.

FIG. 5 shows a control block for performing the above-mentioned feedback control in the motor control device 42. Each code has the following meaning. rv: target speed value (target speed) rp: target position value (target position) ev: speed deviation ep: position deviation Kv: speed gain Kp: position gain Gc: controller Gp: control target (motor) y: position dy / dt : Position change amount (speed) u: Operation amount (Kvev + Kpep)

FIG. 7 shows a modification of the optical system of the scan position detecting device. The same parts as those shown in FIG. 1 are designated by the same reference numerals, and the duplicated description will be omitted.

The rotary mirror 64 is a single-sided mirror having only one surface formed as a mirror surface, and is vertically long. The upper half of the rotating mirror 64 is a region that reflects the distance measuring light, and the lower half is a region that reflects the detecting light.

FIG. 8 shows still another example. The laser diode 21 for detecting the scan position in FIG. 7 is omitted. A part of the position detecting element 22 has entered a part of the optical path of the distance measuring light reflected by the rotating mirror 64 and projected to the outside, and the position detecting element 22 determines the incident position of this distance measuring light. Outputs the indicated position signal.

[Brief description of drawings]

FIG. 1 shows an optical arrangement of a scan position detecting device.

FIG. 2 is a graph showing a change over time of a scan angle.

FIG. 3 is a time chart showing the timings of distance measuring light, received light, and detection light.

FIG. 4 is a block diagram showing a configuration of a scan position control device.

FIG. 5 is a block diagram showing a configuration of a motor control device.

FIG. 6 is a flow chart showing a processing procedure of a distance measurement CPU.

7A and 7B show a modification of the optical configuration of the scan position detecting device, in which FIG. 7A is a plan view and FIG. 7B is a side view.

FIG. 8 shows another modification of the optical configuration of the scan position detecting device.

[Explanation of symbols]

 11 Laser diode for distance measuring light 12 Lens system 13 Fixed mirror 14, 64 Rotating mirror 15 Motor 21 Optical laser diode for scanning position detection 22 Position detection element (PSD) 41 Distance measurement CPU 42 Motor controller

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Wataru Ishio 10 Odoron-cho, Hanazono Dodo-cho, Ukyo-ku, Kyoto City, Kyoto Prefecture

Claims (3)

[Claims] 1. A distance measuring light source for generating distance measuring light, a detecting light source for generating scan position detecting light, the distance measuring light reflected and emitted to the outside, and the detecting light source. A rotating mirror that reflects light, and a position that is arranged at a position where the detection light reflected by the rotating mirror enters in a rotation angle range of the rotating mirror and that outputs a position signal that represents the incident position of the detection light. Detection element,
Scan position detecting device in a distance measuring device equipped with. 2. A detection light source for generating light for scanning position detection, a rotary mirror for reflecting the detection light in a region other than a region used for reflecting the distance measuring light, and rotation of the rotary mirror. A scan position detecting device provided with a position detecting element arranged in a position where the detecting light reflected by the rotating mirror is incident in an angular range and outputting a position signal indicating an incident position of the detecting light. 3. A detection light source for generating light for scanning position detection, a rotary mirror for reflecting the detection light in a region other than a region used for reflecting the distance measuring light, and a rotation angle of the rotary mirror. A position detecting element which is arranged at a position where the detecting light reflected by the rotating mirror is incident and which outputs a position signal indicating the incident position of the detecting light, a scan motor which rotates the rotating mirror, The target value command device that gives the target value of the scan motor at fixed time intervals, and the position of the scan motor that receives the target value given by the target value command device and the position signal output from the position detection element as input. A scan position control device comprising a motor control device for controlling the scan motor so that the above-mentioned target value agrees with the target value.