CN100424540C - Large-aperture optical periscope laser radar 3D scanning device - Google Patents

Abstract

The present invention discloses a large-bore optical periscope type radar 3-D Scanner which comprises a plane reflection mirror, a horizontal rotation mechanism and a vertical rotation mechanism, wherein the plane reflection mirror is arranged on the horizontal rotation mechanism and the vertical rotation mechanism at a 45 DEG angle. The vertical rotation mechanism and the horizontal rotation mechanism are rotationally connected. The lower end of the vertical rotation mechanism is provided with a rotary disk, and both the horizontal rotation mechanism and the vertical rotation mechanism are driven through a worm wheel and worm rod driving mechanism. The present invention has the advantages of high scanning accuracy, high system stability, simple control and convenient installation, and can be butted with a reception system in a long distance.

Description

Large-aperture optical periscope laser radar 3D scanning device

technical field

The invention relates to a three-dimensional scanning device of laser radar.

Background technique

Optical scanning is often used in optical instruments, especially in atmospheric detection, lidar scanning, aerial cameras, laser marking and other systems. The most commonly used scanning method in the scanning system is the scanning method of a single plane mirror. For example, the MSS scanning mirror of the spectral scanner on the land satellite is an elliptical plane mirror with a long axis of 33cm and a short axis of 23cm. The optical system is at 45 degrees and oscillates at a frequency of 13.65Hz to achieve scanning; the horizontal and vertical rotation of the single mirror is used to realize 3D laser scanning and close-range photography in shipbuilding. In addition, the scanning system often uses rotation Mirror drum, refracting prism column, rotating refracting wedge, rotating V-shaped mirror, double plane mirror rotating scanning. In the lidar monitoring system, the rotating main lens barrel is often used for scanning.

Contents of the invention

The purpose of the present invention is to provide a large-aperture optical periscope laser radar three-dimensional scanning device, which can be widely used in laser radar systems and scanning imaging systems, especially in some systems that require relatively high scanning accuracy.

A large-caliber optical periscope laser radar three-dimensional scanning device, including a plane mirror, a horizontal rotation mechanism, and a vertical rotation mechanism, is characterized in that a 45-degree plane mirror is installed on the vertical rotation box, and the side of the vertical box The outer ring is installed on the vertically rotating inner ring, the outer ring of the vertically rotating inner ring is fixed with a turbine, the vertically rotating inner ring is covered with a vertically rotating outer ring, and a radial bearing is installed between the vertically rotating outer ring and the vertically rotating inner ring. The rotating outer ring is fixedly connected with the horizontally rotating box, and a support is fixed on the horizontally rotating box, and a vertically rotating worm gear transmission mechanism is fixedly installed on the support, which cooperates with the turbine on the vertically rotating inner ring; A 45-degree plane reflector is installed parallel to the plane reflector installed in the vertically rotating box. A horizontally rotating inner ring is fixedly installed under the horizontally rotating box. A turbine is installed outside the horizontally rotating inner ring. The horizontally rotating inner ring is fixed in the hollow On the turntable, there is a fixed base plate under the turntable, and there are circumferential grooves on both the base plate and the turntable, and the plane supporting rings are respectively fixed in the circumferential grooves, and there are steel balls between the upper and lower circumferential grooves.

The three-dimensional scanning device is characterized in that the plane reflector is fixed on a mirror base, and the mirror base is further fixed on a horizontal rotating box or a vertical rotating box.

The three-dimensional scanning device is characterized in that the lower part of the turntable is fixedly connected to the positioning inner ring, the lower part of the substrate is connected to the positioning outer ring, and a centripetal bearing is installed between the positioning inner ring and the positioning outer ring.

The three-dimensional scanning device is characterized in that a counterweight is installed outside the horizontally rotating box.

The accuracy index of the present invention is as follows:

(1) Periscope scanning mirror:

Horizontal scanning angle range: -180°-180°;

Angular velocity: >5°/sec;

Vertical scanning angle range: -5°-95°;

Angular velocity: >5°/sec;

(2) When the two scanning mirrors rotate, the optical axis swings <5';

(3) Parallel deviation of two plane mirrors < 5';

(4) The horizontal scanning and vertical scanning of the periscope scanning mirror have zero-angle identification devices respectively.

The advantages of the present invention are as follows: 1. Under the control of the computer, the rotation of the plane reflector is realized by using the worm gear transmission principle, so that the scanning part becomes an independent component and is widely used in the laser radar system, avoiding the problems caused by the rotating telescope system. Inconvenience. 2. Since it is an independent system, there is a large margin in the installation site, and it can be separated from the lidar telescope, which greatly reduces the limitation on the installation space. 3. The entire scanning system is controlled by a computer, which guarantees a certain degree of control accuracy and avoids the inconvenience and shortage of manual operation. 4. High scanning precision, good system stability, simple and convenient control. Since the system has an independent installation method, there is no distance limit on the installation space, and it can be connected to the receiving system at a long distance, which is quite convenient for installation. The computer control technology is used to avoid the inconvenience of manual operation; because the limit device is added to the system, the reliability of the system operation is improved.

Description of drawings

Fig. 1 is a schematic diagram of the structure of the present invention.

Fig. 2 is a schematic diagram of the scanning principle of the present invention.

Fig. 3 is a schematic diagram of the scanning space of the three-dimensional scanning mechanism of the present invention.

Figure 4 Worm gear drive mechanism.

Fig. 5 is a schematic diagram of the principle of an incremental angular displacement encoder.

Fig. 6 is a structural diagram of a planar support ring.

Fig. 7 is a structural diagram of a plane reflector seat.

Fig. 8 is a sectional view of the vertically rotating box.

Fig. 9 is a three-dimensional structural view of the vertically rotating box.

Fig. 10 is a sectional view of the horizontally rotating box.

Fig. 11 is a three-dimensional structural view of the horizontal rotating box.

Fig. 12 is a structural diagram of a plane mirror.

Detailed ways

See Figure 1~Figure 10. Each label in the figure: 1. Plane reflector, 2. Plane reflector base, 3. Vertically rotating box, 4. Vertically rotating inner ring, 5. Vertically rotating outer ring, 6. Centripetal bearing, 7. Horizontally rotating box Body, 8, horizontal counterweight, 9, vertical counterweight, 10, worm gear transmission mechanism, 11, fixed base, 12, positioning outer ring, 13, positioning inner ring, 14, centripetal bearing, 15, plane support ring , 16, steel ball, 17, support, 18, horizontal protective cover, 19, horizontal rotating inner ring, 20, turntable, 21, base plate, 22, worm, 23, motor, 24, incremental angular displacement encoder, 25, power line, 26, control line, 27, computer, 28 turbo.

A large-caliber optical periscope laser radar three-dimensional scanning device. The plane reflector 1 is fixed on the mirror base 2. There are two groups in total. One set of mirror bases 2 is fixed on the vertical rotating box 3. The plane reflector 1 becomes Installed at 45 degrees, the side outer ring of the vertically rotating box body 3 is installed on the vertically rotating inner ring 4, the outer ring of the vertically rotating inner ring 4 is fixed with a turbine, and the outer ring of the vertically rotating inner ring 4 is covered with a vertically rotating outer ring 5, and the vertically rotating outer ring A centripetal bearing 6 is installed between the ring 5 and the vertically rotating inner ring 4, the vertically rotating outer ring 5 is fixedly connected with the horizontally rotating box 7, and a support 17 is fixed on the horizontally rotating box, and a vertical shaft is fixedly installed on the support 17. The rotating worm gear transmission mechanism 10 cooperates with the worm gear on the vertically rotating inner ring 4; another group of plane reflectors 1 and mirror base 2 are installed on the horizontally rotating box 7, and the plane reflector 1 is also installed at 45 degrees. The plane reflector 1 installed in the vertical rotation box 3 is parallel, and the bottom of the horizontal rotation box 7 is fixedly installed with a horizontal rotation inner ring 19, and a turbine is installed outside the horizontal rotation inner ring 19, and the horizontal rotation inner ring 29 is fixed on a hollow turntable 20, below the turntable 20 is a hollow fixed base plate 21, the base plate 21 and the turntable 20 have circumferential grooves, and plane support rings 15 with high flatness precision are respectively fixed in the grooves, and steel balls 16 are between the upper and lower plane support rings 15 It rolls around the central axis to support and reduce friction. The substrate 21 is fixedly installed on the fixed base 11 .

The lower part of the turntable 20 is fixedly connected to the positioning inner ring 13 , the lower part of the base plate 21 is connected to the positioning outer ring 12 , and a centripetal bearing 14 is installed between the positioning inner ring 13 and the positioning outer ring 12 .

Figure 1 is a schematic cross-sectional view of the optical-mechanical system for periscope scanning with an optical aperture of Φ300mm. The present invention adopts a periscope double-plane reflector structure in the optical system, and the two plane reflectors are placed parallel to the chief light at 45 degrees, and the reflectors are coated with a high-reflection film according to actual usage conditions. Since the reflector is placed at 45 degrees, the clear aperture on the reflector is elliptical; in the scanning system with clear aperture Φ300mm, the actual aperture of the reflector is an ellipse with major axis a=424mm and minor axis c=300mm, considering the processing And clamping, the actual two planar reflectors are made into an octagon. The three-position scanning rotation principle of the periscope laser radar is shown in Figure 2. Its rotation system consists of horizontal rotation and vertical rotation. When rotating horizontally, the two mirrors rotate as a whole; when rotating vertically, only the mirror in the vertical direction rotates. , and its scanning space schematic diagram is shown in Figure 3.

1. Realization of vertical rotation

It can be seen from Figure 1 that the plane reflector 1 is fixed on the mirror base 2 in the form of suspension, and the mirror base 2 is connected with the vertically rotating box 3 by screws, and the box and the vertically rotating inner ring 4 are positioned with positioning pins The connection improves positioning accuracy and rotation stability. The vertically rotating inner ring 4 is connected with the worm gear. In order to control the swing amount of the axis when rotating, two large-diameter radial bearings 6 are installed between the inner ring 4 and the outer ring 5; the vertical rotating part passes through the outer ring 5 and the horizontal rotating box Body 7 is connected. In this way, when the motor drives the worm gear mechanism 10, the vertical rotation of the box and the flat mirror on it can achieve vertical rotation. And outer ring 5 and box body 7 can keep static state.

2. Realization of horizontal rotation

Horizontal rotation needs to consider factors such as system installation and weight, so the horizontal rotation structure is more complicated. The rotating system of horizontal rotation is shown in Figure 1. The plane reflector 1 is also fixed on the mirror base 2 in the form of suspension, and the mirror base 2 is fixed on the box body 7. The entire rotating part is finally connected with the rotating inner ring 13, and the rotating inner ring Between 13 and the rotating outer ring 12 are two large-diameter centripetal bearings 14, which bear the weight of the whole system. Driven by the worm gear transmission mechanism 10, the horizontal rotation of the entire rotating system is realized. In order to reduce the friction force and the amount of optical axis shaking, steel balls 16 are used for support, and the steel balls 16 are placed on two high-flatness support rings 15. Rolling, used to bear the gravity of the entire scanning mechanism, avoiding excessive axial force on the radial bearing.

The design of the steel ball is actually to calculate the minimum diameter required by the steel ball, the formula is:

$\mathrm{<span\; class="notranslate">\; d</span>}<span\; class="notranslate">\; =</span>\sqrt{\frac{{\mathrm{<span\; class="notranslate">\; Q</span>}}_{\mathrm{<span\; class="notranslate">\; k</span>}}}{\mathrm{<span\; class="notranslate">\; C</span>}}}<span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; )</span>$

In the formula, C—the allowable load strength of the steel ball material, about 780-980N/cm ²

Q _k ——calculated load, its calculation formula is

Q _k =Q ₀ ·a ₁ ·a ₂ ·a ₃ (2)

Where a ₁ ——Considering the coefficient of the rotation of the seat ring, 1.4 is taken here;

a ₂ —coefficient considering the load condition, here take 1.8;

a ₃ ——Considering the coefficient of working hours, take 2 here;

Q ₀ ——When bearing axial load, the maximum load on the steel ball, the calculation formula is

${\mathrm{<span\; class="notranslate">\; Q</span>}}_{\mathrm{<span\; class="notranslate">\; 0</span>}}<span\; class="notranslate">\; =</span>\frac{\mathrm{<span\; class="notranslate">\; Q</span>}}{\mathrm{<span\; class="notranslate">\; 0.8</span>}\mathrm{<span\; class="notranslate">\; z</span>}\mathrm{<span\; class="notranslate">\; cos</span>}\mathrm{<span\; class="notranslate">\; \&alpha;</span>}}<span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 3</span>}<span\; class="notranslate">\; )</span>$

Among them, Q - total axial load, according to all loads is about Q = 210kg;

z—the number of steel balls used, the number of steel balls used in this system is 60;

α——the angle between the force direction of the steel ball and the axis, and α is zero in this system.

Substituting the data, we can get:

Q _k =Q ₀ ·a ₁ ·a ₂ ·a ₃ =4.79×1.4×1.8×2=24.15kg=236.7N;

$\mathrm{<span\; class="notranslate">\; d</span>}<span\; class="notranslate">\; =</span>\sqrt{\frac{{\mathrm{<span\; class="notranslate">\; Q</span>}}_{\mathrm{<span\; class="notranslate">\; k</span>}}}{\mathrm{<span\; class="notranslate">\; C</span>}}}<span\; class="notranslate">\; =</span>\sqrt{\frac{\mathrm{<span\; class="notranslate">\; 236.7</span>}}{\mathrm{<span\; class="notranslate">\; 780</span>}}}<span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; 0.55</span>}\mathrm{<span\; class="notranslate">\; cm</span>}<span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; 5.5</span>}\mathrm{<span\; class="notranslate">\; mm</span>}$

Therefore, the strength of steel balls with a diameter of 10mm is sufficient in this system.

3. Turbine and worm drive mechanism

The worm gear transmission mechanism is shown in Figure 4, the worm gear 28 and the worm screw 22 are driven by the motor 23, the incremental angular displacement encoder 24 is connected behind the motor, the motor and the encoder communicate with the control system and the computer 27 through the power line 25 and the control line 26 connected. A stepper motor is an actuator that converts electrical pulses into angular displacement. When the stepper driver receives a pulse signal, it drives the stepper motor to rotate a fixed angle (that is, the step angle) in the set direction. The angular displacement can be controlled by controlling the number of pulses, so as to achieve the purpose of accurate positioning, and at the same time, the speed and acceleration of the motor rotation can be controlled by controlling the pulse frequency, so as to achieve the purpose of speed regulation. The stepping motor selected by the present invention is a two-phase hybrid type, and the step angle is 1.8° (0.36° after being subdivided by the driver). Because the moment of inertia of the scanning mechanism is very large, when the stepper motor starts and stops, it may not fully respond to one control pulse, but another pulse has arrived. This out-of-step phenomenon will greatly affect the control accuracy. The solution is to add zero angle discriminator and incremental angular displacement encoder 24 in the system. Incremental angular displacement encoder is a pulse disc angle digital sensor. Its schematic diagram is shown in Figure 5. Radial slits (divided into light-transmitting and opaque parts) with equal angular distances are engraved on the edge of the disc. A light source and a photosensitive element are respectively installed on both sides of the slit disc. When the disc rotates with the working shaft, the light and shade will change every time it turns through a gap. A change in electrical signal is generated by the photosensitive element. After shaping and amplifying, an electric pulse output signal with a certain amplitude and power can be obtained. The number of pulses is equal to the number of slots turned. The output pulse signal is sent to the counter for counting, and the disc rotation angle value can be obtained from the obtained count value.

The two ends of the stepper motor are equipped with a protruding shaft, one end is connected to the worm, and the other end is connected to an angular displacement encoder, which is used to monitor the rotation angle of the shaft. The minimum error of this counting method is the angular resolution of the angular displacement encoder, that is, the angle that the rotating shaft rotates every time a pulse is generated. Therefore, the influence of the counting method on the control accuracy can be expressed by the following formula:

$\mathrm{<span\; class="notranslate">\; \&Delta;</span>}{\mathrm{<span\; class="notranslate">\; \&theta;</span>}}_{\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; =</span>\frac{\mathrm{<span\; class="notranslate">\; 360</span>}<span\; class="notranslate">\; /</span>\mathrm{<span\; class="notranslate">\; N</span>}}{\mathrm{<span\; class="notranslate">\; i</span>}}<span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 4</span>}<span\; class="notranslate">\; )</span>$

In the formula, Δθ ₂ ——the influence of the angular resolution of the angular displacement encoder on the control accuracy (°);

N——The number of pulses generated by the grating disk in the angular displacement encoder for one revolution;

i——total transmission ratio.

The engraved lines of the grating disk are generally dense, so the N value is very large, and then subdivided by 1/168, so after the angular displacement encoder is used, the influence of the angle counting method on the control accuracy is minimal. Using computer programming to realize the synchronous rotation of the incremental angular displacement encoder and the motor, under the strict control of the photoelectric switch and travel switch, the scanning mechanism can scan the three-dimensional space at a given angle.

The calculation of the worm gear in the scanning mechanism with a diameter of Φ300mm is as follows:

(1) Calculation of worm head number Z ₁ , worm gear tooth number Z ₂ and transmission ratio i:

According to the actual optical and mechanical dimensions, the overall dimensions of the worm gear are determined as follows:

Worm gear: outer diameter Φ430mm, inner diameter Φ336mm, thickness 35mm;

Worm: diameter Φ35mm

Take the modulus m=2, 5, and the diameter of the worm gear index circle is d2=420mm, then the number of worm gear teeth is:

Z ₂ =d ₂ /m=420/2.5=168

Because the transmission ratio in this example is relatively large, the number of worm heads can be taken as Z1=1, and the transmission ratio is: i=Z ₂ /Z ₁ ＝168

Therefore, it can be determined that the number of worm heads Z ₁ =1, the number of worm gear teeth Z ₂ =168, and the transmission ratio i=168.

(2) Select material and determine its allowable stress:

The material of the worm pair not only requires sufficient strength, but more importantly, it must have good anti-friction and wear resistance properties. Therefore, ZQSn10-1 is used as the material of the worm gear, which has good anti-gluing and anti-wear properties and a high allowable sliding speed. , and easy to cut; the material used for the worm is 40Cr, and the surface is hardened to HRC40-45, with high hardness.

It is estimated that the relative sliding speed between the worm gear and the worm screw does not exceed 0.5m/s during normal operation, and the allowable contact stress of the worm gear is [σ _H ]=180N/mm ² .

(3) Calculation of modulus m, diameter coefficient q and geometric dimensions:

In the first step, m=2 and 5 have been taken, and the diameter of the worm pitch circle is d1=30mm, then the diameter coefficient is q=d ₁ /m=30/2.5=12

The calculation formulas and results of other geometric dimensions are shown in Table 1

4. Design of counterweight

In order to make the system run smoothly, counterweights are designed for the horizontal and vertical rotating mechanisms respectively. This part of the content is completed with the help of PRO/E software. In the Assembly (assembly) mode, first design the rough model of the scanning mechanism, and then input the density value of the part according to the material of each part, and then analyze the mass properties of the entire model.

The counterweight is carried out in two parts. Firstly, the vertical rotation mechanism should be counterweighted, and then the horizontal rotation mechanism should be counterweighted. The two process methods are the same, and only the counterweight process of the horizontal rotation mechanism will be introduced here.

Since the horizontal rotation mechanism drives the vertical rotation mechanism to rotate together when it is running, the vertical rotation mechanism must be added to the analysis when balancing the horizontal rotation mechanism. This is also the reason why the vertical mechanism must be counterweighted first.

The total weight of the system before counterweight is about G = 173 kg. This is the key parameter to use for the counterweight. To reduce the offset of the center of gravity relative to the horizontal axis of rotation, counterweights are added in the opposite direction. Materials with high density and low cost should be used, such as cast iron. In the design, the counterweight is installed at a position slightly away from the rotating shaft, so that the total weight of the system can be reduced while achieving the same counterweight effect. When adding counterweights, it is not necessary to accurately calculate how much weight to add. You can analyze the quality attributes immediately after adding a certain counterweight. If you are not satisfied, you can easily change the volume (weight) of the counterweights and analyze again until you are satisfied.

According to the PRO/E software, the weight of the counterweights 8 and 9 is calculated to be 37 kg, plus the base plate 11 and the protective cover 18 with a total weight of 20 kg, the total weight of the three-dimensional scanning system is about 230 kg.

Claims (4)

1. large-bore optical periscope type radar 3-D Scanner, include plane mirror, horizontally rotate casing, with vertical rotating box, it is characterized in that being equipped with on the vertical rotating box 45 degree plane mirrors, on the outer ring, side of vertical rotating box is installed in and encircles in the vertical rotation, the ring outer ring is fixed with turbine in the vertical rotation, be with vertical rotation outer shroud outside the ring in the vertical rotation, vertical rotation outer shroud is equipped with radial bearing between encircling with vertical rotation is interior, vertical rotation outer shroud with horizontally rotate casing and fixedly connected, horizontally rotate and be fixed with bearing on the casing, be installed with vertical revolving wormgear scroll bar gear train on the bearing, with the turbine cooperation on the ring in the vertical rotation; Horizontally rotate 45 degree plane mirrors are installed on the casing, parallel with the plane mirror of installing in the vertical rotating box, the below that horizontally rotates casing is installed with and horizontally rotates interior ring, the outer turbine that is equipped with of ring in horizontally rotating, ring is fixed on the rotating disk of hollow in horizontally rotating, and the rotating disk below is the substrate of fixing, and circumferential groove is all arranged on substrate and the rotating disk, difference fixed pan support ring has steel ball between two circumferential grooves up and down in the circumferential groove.

2. device according to claim 1 is characterized in that described plane mirror is fixed on the microscope base, and microscope base is fixed on and horizontally rotates on casing and the vertical rotating box.

3. device according to claim 1 is characterized in that described rotating disk below is fixedly connected on ring in the location, and the substrate below is connected with the location outer shroud, between ring and the location outer shroud radial bearing is installed in the location.

4. device according to claim 1 is characterized in that the described casing outside that horizontally rotates is equipped with balancing weight.

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