JPH0551109B2 - - Google Patents

Description

[Detailed description of the invention]

[Industrial Application Field] The present invention relates to an automatic collimating optical range finder, and is particularly suitable for use in a marine work system in which a coastal work platform moves over a wide range. [Summary of the invention] A light wave distance meter is provided on the fixed station side and a reflector is provided on the mobile station side, and each of the fixed station and mobile station receives collimated servo light transmitted from the other station. A collimation servo system including an objective lens and a position sensor is provided, and these collimation servo systems align the optical axis of the objective lens with the optical axis of the collimation servo light to connect the fixed station and the mobile station to each other. Aim. The response speed of the collimating servo system to the collimating servo light of a relatively moving partner station is made slower for the fixed station than for the mobile station, and the collimating servo light is temporarily blocked by obstacles etc. This automatic collimating optical distance meter device maintains the tracking speed of the fixed station relative to the mobile station at the average value over a certain period of time immediately before the mobile station, allowing stable speed over a wide angular range. It is. [Prior Art] In civil engineering work, port construction work, coastal construction work, etc., there is a need for a system that measures the position or distance of a moving object such as a bulltozer, dredger, work boat, etc. from a fixed position. Conventionally, a light wave distance meter is used on one side of a fixed position and a moving object, and a reflector (corner cube prism, etc.) on the other side.
There is a known system in which the optical axis is automatically collimated so that the position can be measured without any problem even if a moving object such as a ship's platform swings. Publication No. 8221). A known automatic collimation type light wave rangefinder has a collimation servo optical axis parallel to the rangefinder, and splits the collimation servo light from a fixed station into four light receiving elements (the light receiving surface is divided into four horizontal and vertical quadrants). It is equipped with a servo system that receives the output from a divided photodiode (such as a split photodiode) and feeds the output back to the horizontal and vertical oscillation motors to image the servo light at the origin of the light receiving element. Since the distance measurement data from the rangefinder is used on the ship's platform side, the distance meter is usually placed on the ship's platform side and the reflector is placed on the shore side. A land station with a reflector is equipped with a collimating servo light source and a light transmitting lens, and the optical axis of the light transmitting lens is fixed toward the platform station. The platform station automatically collimates to match its own optical axis with respect to this fixed optical axis. [Problems to be solved by the invention] As mentioned above, conventional systems are semi-automatic, and when the platform moves over a wide range, a worker on the shore side redirects the reflector to match the movement of the platform. The need arose. In order to make it fully automatic, it must be bidirectionally collimated, but the following problems arise. It is better to keep the optical axis of the collimating servo light from the land station as fixed as possible to stabilize the third system when the platform station collimates to the land station. In other words, the servo system of the platform station refers to the servo light from the land station as the reference optical axis.
It detects the deviation of the optical axis of its own objective lens and operates to correct this deviation. Therefore, it is undesirable for the reference optical axis itself to fluctuate. However, when bidirectional collimation is used, there is no correction with respect to the reference, and corrections are made to each other so that the angular difference in the optical axes of the objective lenses is eliminated. When collimation is achieved, each optical axis coincides with a straight line connecting the platform station and the land station. However, if we consider the case where the optical axes of each station are somewhat offset from the other station but parallel to each other, in this case too, there is no difference in the angle of the optical axes, and moreover, both parallel rays form an image at each focal point, so each station In this case, there is no error detection and no optical axis correction is performed. There are countless parallel relationships between optical axes like this. This means that in bidirectional collimation, there is no stable point in the servo system, and each collimation point is not fixed at one point. In view of this problem, an object of the present invention is to enable stable operation of a servo system even in bidirectional collimation, and to enable automatic collimation and distance measurement over a wide angular range. [Means for solving the problem] As shown in Fig. 1, a light wave distance meter 3 is provided on the fixed station (land station) side, and a reflector 4 is provided on the mobile station (ship station) side for distance measurement. system is configured. A servo system optical axis having a pair of objective lenses (light receiving lens 13 and light transmitting lens 12) is provided parallel to the distance measuring system optical axis. A position sensor 23 that is perpendicular to the optical axis of the servo system and detects the deviation of the imaging point from the origin is provided in both the fixed station and the mobile station.
Using the output of the position sensor 23, a collimating servo system is configured to swing the optical axis of the objective lens horizontally and vertically to aim at the partner station. Regarding the response speed of the collimation servo system to time variations in the optical axis deviation of the collimation servo light, we set the response speed of the fixed station slower than the response speed of the mobile station, and set a reference axis in which the collimation servo light of the fixed station does not fluctuate suddenly. is configured to do so. When the servo light from the mobile station is temporarily blocked by an obstacle etc. as the mobile station moves, the fixed station can maintain its function as a reference. Figure 9, block B1) and
Speed maintenance means (Figure 9, block B) that maintains the tracking speed of the fixed station with respect to the mobile station (each speed of optical axis deflection) at the average value within a certain period of time immediately before the time of light interruption.
2) are provided at each fixed station. In addition, according to the general theory of control systems, the response speed of the collimating servo light to the time variation of the optical axis deviation of the collimating servo light corresponds to the time constant of the temporary delay element (integral element) of the servo system, and the response speed Fast speed means that the time constant is small and the upper limit of the frequency that can respond is high.
A slow response speed means that the time constant is large and the upper limit of the frequency to which it can respond is low. In addition, the tracking speed is the angular velocity of the output axis (horizontal and vertical optical axis deflection axes) of the servo system during tracking operation, and in the embodiment of the present invention, when the optical path is temporarily shaded, the average speed for several tens of seconds is The tracking (tracking) speed of the fixed station relative to the mobile station is maintained. [Function] Since both the fixed station and the mobile station are equipped with collimation servo systems, both the fixed station and the mobile station can automatically aim at the other station, allowing the mobile station to move over a wide range. It can be automatically followed in any case. In this way, both the fixed station and the mobile station are configured to automatically aim at the other station, but since the servo time constant on the fixed station side is set large, the fast optical axis fluctuations on the mobile station side are fixed. The servo optical axis of the station is almost fixed. Therefore, the mobile station corrects its optical axis fluctuations with reference to this fixed servo optical axis. On the other hand, the fixed station does not collimate by following the rapid optical axis fluctuations of the mobile station, but operates to track the slow movement of the mobile station. In addition, when a fixed station is tracking a mobile station, when the mobile station's collimation servo light is blocked by an obstacle, the fixed station's tracking speed with respect to the mobile station is maintained at the previous average value. without losing sight of the mobile station.
The operation of the collimation servo system is not hindered by obstacles or the like. [Embodiment] Fig. 1 is an overall block diagram of an optical ranging system for marine work showing an embodiment of the present invention, and Figs. 2 and 3 are front views of each ranging device of a land station and a berth station. It is a diagram. Each station is equipped with an automatic sighting device 2 provided on a base 1, a light wave distance meter 3 is provided at the land station, and a reflector 4 is provided at the boat station. The optical distance meter 3 includes an objective lens 5, and the reflector 4 includes a corner cube prism 6. The collimation device 2 includes a horizontal arm 7 that is rotatable in a horizontal plane and a vertical arm 8 that is rotatable in a vertical plane.
They are driven by an X-axis gear motor 9 and a Y-axis gear motor 10, respectively. A light transmitting/receiving unit 11 is mounted on the vertical arm 8 and includes a light transmitting lens 12 and a light receiving lens 13 whose optical axes are parallel to each other.
As shown in FIG. 1, in the land station and the platform station, the transmission and reception of the lenses 12 and 13 face each other, forming a pair of light transmission path 14 and light reception path 15 (with respect to land). FIG. 1 shows a collimating optical system 2a of an automatic collimating device 2.
Although the collimation servo circuit and optical communication circuit connected to the (land station) are shown, the same circuit is also attached to the collimation optical system 2b of the platform station, so that bidirectional collimation can be performed. It's getting old. Collimation optical system 2
A light emitting diode 20 for light transmission is arranged at the focal point of the light transmission lens 12, and the sine wave output (5k
Hz) is supplied via the LED drive circuit 22.
As a result, the AM-modulated collimating servo light passes through the light transmitting lens 12 and enters the light receiving lens 13 of the collimating optical system 2b on the ship's platform side, and forms an image on the position sensor 23 disposed at its focal point. On the other hand, the collimated servo light, which is also AM-modulated, is emitted from the light-transmitting light emitting diode 20 in the optical system 2b on the ship's platform side through the light-transmitting lens 12 toward the land station, and is transmitted through the light-receiving lens 13 of the land station. The light is received by the position sensor 23. Note that the collimated servo light sent from the land station optical system 2a to the platform station is reflected by the reflector 4 of the platform station and returns to the light receiving system of the own station, becoming a disturbance signal for the servo system. In order to prevent this, the AM modulation frequency of the collimation servo light of the ship's platform station was changed to 3kHz as shown in Figure 4A.
The AM modulation frequency of the land station is 5kHz. The land station servo system selects the frequency of the received servo signal as described later, responds only to the servo light (3kHz) from the platform station, and responds only to the return light (5k) from the own station.
Hz) interference is eliminated. The position sensor 23 may be, for example, a two-dimensional (XY plane) semiconductor position detection element that detects the position of the light spot from the origin. This element has a structure in which four electrodes (two pairs of X and Y) are provided on the four sides of a photodiode with a rectangular light-receiving surface, and the charge generated at the position hit by the light spot is transferred to each electrode as a photocurrent. The light is divided by the resistive layer on the light receiving surface in inverse proportion to the distance from the light receiving surface and taken out from each electrode. In FIG. 1, the output of each electrode of the position sensor 23 passes through current-voltage conversion amplifiers 24a-d, bandpass filters 25a-d, and detectors 26a-26d.
It is synchronously detected at d and converted into a DC level signal with a level value corresponding to the light receiving position. The detection outputs of the four poles are converted into digital values by the A/D converter 27 as upper and lower (U, D) and left and right (L, R) position detection signals, and then sent to the system controller 28.
is incorporated into the internal microprocessor. Note that the bandpuff filters 25a to 25d are shown in FIG. 4A.
As shown in the figure, it has a bandpass characteristic BM centered at 3kHz, allowing only the 3kHz servo signal from the ship's platform station to pass through, and eliminating interference caused by the return light of the 5kHz servo light from the local station (land station). In the microprocessor, the X-Y coordinate position of the light receiving spot on the light receiving surface of the position sensor 23 is calculated from the U, D, L, and R position detection data.
The system controller 28 uses the motor drive circuits 30X and 3 for each axis based on this coordinate position data.
Deriving the drive pulse to 0Y, this causes the X axis, Y
Gear motors 9 and 10 of the shafts are respectively driven. In the servo loop from the position sensor 23 to the motors 9 and 10, the light receiving spot of the sensor 23 is located at the X-
Operates to locate at the origin of the Y coordinate. When the servo is activated, the optical axes of the collimating optical systems 2a and 2b of the land station and the platform station coincide. As a result,
The optical axis of the land station's optical distance meter 3 is the reflector 4 of the ship's platform station.
When the object is pointed correctly, distance measurement becomes possible. Note that the platform station is equipped with a similar collimation servo system, so the two opposing stations collimate each other. Means for finely adjusting the direction of the optical axis of the collimation device 2 of each station is provided. In FIG. 1, this fine adjustment means is a joystick 31, but fine adjustment knobs may be provided in the gear systems of the motors 9, 10 for each XY axis. Voltage output corresponding to the operation of the joystick 31 in the X and Y directions is sent to the system controller 28 via the A/D converter 32, and from the controller 28 to the motor drive circuits 30X, 30.
Fine adjustment drive pulses are derived from Y and each motor 9,
10 is slightly moved. Therefore, the operator operates the joystick 31 while looking through the sighting telescope of the optical distance meter 3 to sight the other station. When the servo start button is pressed when the sighting is completed, the above-mentioned sighting servo starts, and then bidirectional automatic sighting follows the sway and movement of the boat platform. The deviation of the optical axis detected by the position sensor 23 is displayed on indicators 33A to 33C connected to the system controller 28. Display device 33A,
Each pointer 33B indicates the deviation from the origin of the X axis (horizontal direction) and the Y axis (vertical direction). The pointer of the display 33C indicates the overall light reception level (light reception intensity) of the position sensor 23. When the circuit section 34 of the optical distance meter 3 operates in the collimated state, the light transmitting/receiving unit 35 placed at the focal position of the objective lens 5 emits a distance measuring light of approximately 15 MHz (AM) and reflects light from the measuring point. is received. The phase difference between the transmitted light and the received light is measured by the circuit section 34, and the station opening distance is calculated based on the phase difference. Distance data is from interface 36.
is transferred to the system controller 28 through
Furthermore, it is sent to the dock station via the modem 37. In this way, since the land station and the platform station each sight the other's station, so that the two-way collimation is achieved, even when the platform station moves over a wide range, automatic aiming can be performed effectively. Figure 6 shows an example of an automatic tracking survey system.
A base line 49 is set, and land stations are installed at both left and right ends A and B, respectively, and two sets of ship platforms corresponding to the land stations are installed on the platform C. When the platform station does not move, the optical axes of the platform station and the land station coincide with each other at optical axes A and A', as shown in FIG. 7a. However, when the platform station moves, for example, in the direction of arrow 60 in Figure 6, if only the platform station is equipped with an automatic sighting device, the light on the platform station's side as shown in b in Figure 7. Axis B-
B' and the optical axis A-A' of the land station picture are greatly misaligned. Therefore, if the platform station is moved significantly, the land station must be reinstalled. However, in this embodiment, an automatic sighting device is also provided on the land station side to achieve bidirectional collimation, so the optical axis of the land station side is swung toward the ship's platform station as shown in Fig. 7c. The optical axes of the station and the land station can be aligned at the optical axis B-B'. The land station is capable of automatic tracking within a range of approximately ±45 degrees centered on the origin position, and even when the platform C moves significantly as shown by arrows 60 and 61 in Figure 6, automatic tracking can be performed over a wide range. can. That is, 1
The surveying range that can be carried out in one installation can be expanded, and surveying work efficiency can be greatly improved. Although bidirectional collimation has the above-mentioned advantages, as mentioned above, there is a problem in that the servo systems of the platform station and land station interfere with each other and become unstable. In order to solve this problem, a servo time constant setting unit 46 is installed in each collimation servo system of the ship's platform station and land station.
An X-axis gear motor 9 and a Y-axis gear motor 1 are provided.
The response speed of the servo system including 0 (time constant of the integral element of the servo system) is set so that the platform station side is high speed and the land station side is slow speed. The servo time constant setting section 46 includes a changeover switch 47 having contacts 47a and 47b. Each contact 47a, 47b
is a capacitor 48 which forms part of the loop filter.
a and 48b are connected with their other ends grounded. One capacitor 48a has a relatively large capacity and provides a long time constant to the servo system, and the other capacitor 48b
has a relatively small capacity and provides a short time constant to the servo system. In addition, the changeover switch 47 and the capacitor 48
a and 48b are coupled to respective outputs of four detectors 26a to 26d (in the vertical and horizontal directions) of a circuit that processes the output of the position sensor 23. At the land station, capacitor 48a is selected to lengthen the servo time constant. On the other hand, at the platform station, the capacitor 48b is selected to shorten the servo time constant. As a result, the platform station performs a collimation servo operation following optical axis fluctuations with a quick period of several seconds due to the influence of waves and the like. On the other hand, a land station is insensitive to such rapid optical axis fluctuations and operates by following very slow optical axis deviations such as the movement of a ship's platform. In other words, the land station assumes that the reference optical axis is at the average position of the optical axis fluctuations of the collimating servo light from the platform station, and uses the servo system to align this reference optical axis with the optical axis of its own objective lens. Operate. On the other hand, at the ship's platform station, the optical axis of the collimating servo light from the land station can be considered to be almost fixed within a period of several seconds, so this optical axis is used as the reference axis and the own optical axis fluctuation due to the rocking of the ship's platform is measured. Based on the detection results, corrective actions are taken to properly aim at the land station. In this way, bidirectional collimation is performed without any problems, and as mentioned above, the corner cube prism 6 is used as the reflector 4 at the platform station, so the optical axis may be slightly shifted due to the rocking of the platform. Stable distance measurement can be performed even when This is because the corner cube prism 6 has the function of reflecting incident light in parallel, and can reflect the incident light toward the light emitting source even when tilted by approximately ±30 degrees. The light transmitting optical path 14 and the light receiving optical path 15 for automatic collimation between the land station and the ship's platform station are used as bidirectional optical communication paths. That is, the transmission terminal S of the modem 37
The output from the select circuit 38 is led to the FM modulator 39, where the 5.5 MHz carrier is FM modulated with the transmission data. The FM output is provided to a transmitting light emitting diode 41 via an LED drive circuit 40. The transmitted data light from this diode 41 is approximately on the optical axis of the light transmitting lens 12 of the collimation servo system.
A cut filter 42 inserted at an angle of 45° causes the light to be placed on the light transmission optical path 14 and sent to the ship's platform station. On the other hand, the platform station is equipped with a similar modem 37, a transmitting light emitting diode 41, etc., and transmits transmitted data light onto the servo light receiving optical path 15 of the land station. At this time, for the same reason as the collimation servo system mentioned above, the FM carrier of the transmitted light from the platform station is set to 5M.
Hz, and the carrier frequency from the land station is 5.5MHz, as shown in Figure 4B. This eliminates self-crosstalk on the land station side due to the presence of the reflected optical path of the distance meter 3. The data transmitted from the platform station is, for example, physical condition correction data for distance measurement such as atmospheric pressure and temperature. The data light transmitted from the ship's platform station to the land station along the light receiving optical path 15 is approximately aligned with the optical axis of the light receiving lens 13.
The light is branched to a light receiving diode 44 by a cut filter 43 inserted at an angle of 45°. The light output of the diode 44 passes through an amplifier 50 and a bandpass filter 51, is demodulated by an FM demodulator 52, and is input to a receiving terminal R of the modem 37. The received data decoded by the modem 37 is introduced into the system controller 28 and used for correction of distance measurement data by the microprocessor. The bandpass filter 51 has a bandpass characteristic BM centered at 5MHz as shown in FIG. 4B, and prevents self-crosstalk of the 5.5MHz carrier as described above. As described above, since the reference servo optical path and the data communication optical path are shared, there arises a problem of mutual interference, particularly data light interfering with the servo system. Therefore, as mentioned above, the modulation frequency is changed between the data light and the servo light.
In addition to separating into 5MHz and 5KHz, the wavelength is 890nm.
It is divided into 1100nm and 1100nm. In other words, the distribution as shown in the table below is used to electrically and physically separate the bands and share the optical path.

〔Effect of the invention〕

As described above, in the present invention, a light wave distance meter is provided on the fixed station side and a reflector is provided on the mobile station side, so that stable measurement can be performed even when the mobile station is shaken. Further, since an automatic reference servo system is provided in each of the fixed station and the mobile station to provide bidirectional collimation, even if the mobile station moves significantly, it can be automatically tracked by following the movement. Therefore, the measurement range that can be performed in one installation can be greatly expanded, and the efficiency of device installation and measurement work can be improved. Furthermore, regarding the response speed of the collimation servo system to time variations in the optical axis deviation of the servo light used for automatic collimation, the response speed of the fixed station is slower than that of the mobile station, so the fixed station In addition to tracking the movement of the station, the mobile station effectively corrects optical axis fluctuations due to its own rocking, vibration, etc., based on the substantially fixed servo optical axis from the fixed station. Therefore, even though two-way collimation is used in which each station sights the other station, mutual interference can be eliminated and stable collimation and measurement can be performed. Additionally, when the fixed station is continuously tracking the mobile station and the mobile station's collimation servo light is temporarily blocked by an obstacle, the tracking speed of the fixed station will be maintained at the previous average value. Therefore, the tracking operation is not obstructed by obstacles, etc., and therefore the fixed station does not lose sight of the mobile station, and continuous measurements can be performed with stable tracking.

[Brief explanation of drawings]

FIG. 1 is an overall block diagram of an optical ranging system for marine work showing one embodiment of the present invention, and FIGS.
The figure is a front view of each distance measuring device of the land station and the ship's platform station, Figure 4 is a frequency distribution diagram of the collimation servo system and optical communication system, Figure 5 is a characteristic diagram of the wavelength cut filter, and Figure 6 is a diagram of the characteristics of the wavelength cut filter.
Figure 7 shows an example of an automatic tracking survey system.
The figure is a diagram explaining the state of the optical axes of the ship's platform station and land station, Figure 8 is a block diagram of the device that adjusts the amount of light entering the position sensor, and Figure 9 shows the procedure for adjusting the amount of received light and creating control pulse data. The flowchart shown in FIG. 10 is a diagram showing an example of the relationship between the number of drive pulses output from the system controller and time. In addition, in the symbols used in the drawings, 1... base;
2...Collimation device, 2a, 2b...Collimation optical system, 3
...Light wave distance meter, 4...Reflector, 5...Objective lens, 6...Corner cube prism, 7...Horizontal arm, 8...Vertical arm, 9...X-axis gear motor,
10... Y-axis gear motor, 11... Light transmitting/receiving unit, 12... Light transmitting lens, 13... Light receiving lens,
14...Light sending optical path, 15... Light receiving optical path, 20...
Light-transmitting light emitting diode, 21... oscillator, 23...
...Position sensor, 35...Light transmitting/receiving unit, 37...
...Modem, 41...Light emitting diode for transmission, 46
...This is the servo time constant setting section.

Claims (1)

[Claims] 1. A light wave distance meter is provided on the fixed station side and a reflector is provided on the mobile station side, and each of the fixed station and mobile station receives collimation servo light transmitted from the other station. and a position sensor disposed on a plane that is orthogonal to the optical axis of the objective lens and includes the focal point of the objective lens, and the collimated servo light is provided with the focal point as the origin of the position sensor. The position sensor detects the deviation between the image point formed on the position sensor through the objective lens and the origin, and deflects the optical axis horizontally and vertically to correct the deviation. By aligning the imaging point of the quasi-servo light with the origin, a collimating servo system is provided that collimates the optical axes of the optical distance meter and the reflector to the other station, and the above-mentioned view from the other station is Regarding the response speed of the above-mentioned collimation servo system to time variations in the optical axis deviation of the quasi-servo light, the response speed of the fixed station is made slower than the response speed of the mobile station, and the collimation servo light from the mobile station is prevented from hitting obstacles, etc. Therefore, there is a detection means for detecting temporary interruption, and in response to the detection signal, the tracking speed (angular speed of optical axis deflection) of the fixed station relative to the mobile station is determined by the average tracking speed within a certain period of time immediately before the detection means. 1. An automatic collimating light wave distance meter device, characterized in that a speed maintaining means for maintaining the same value is provided on the fixed station side.