CN209758984U - anti-collision device for overhead working truck - Google Patents
anti-collision device for overhead working truck Download PDFInfo
- Publication number
- CN209758984U CN209758984U CN201920567871.XU CN201920567871U CN209758984U CN 209758984 U CN209758984 U CN 209758984U CN 201920567871 U CN201920567871 U CN 201920567871U CN 209758984 U CN209758984 U CN 209758984U
- Authority
- CN
- China
- Prior art keywords
- vehicle
- working
- arm
- working arm
- mounted computer
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Active
Links
Landscapes
- Forklifts And Lifting Vehicles (AREA)
Abstract
the utility model discloses an aerial working car collision device belongs to building high altitude construction technical field. Comprises a control device, a vehicle-mounted computer, a vehicle detection device, a display and an alarm device; the working vehicle detection device comprises a working arm length sensor, a working arm angle sensor and a rotary encoder, wherein the working arm length sensor, the working arm angle sensor and the rotary encoder are arranged on a working arm of the working vehicle; the working arm length sensor is used for detecting the telescopic length of the working arm of the working vehicle in real time and transmitting information to the vehicle-mounted computer; the working arm angle sensor is used for detecting the amplitude variation angle of the working arm of the working vehicle in real time and transmitting information to the vehicle-mounted computer; the rotary encoder is used for detecting the rotary angle of the rotary body of the operation vehicle in real time and transmitting information to the vehicle-mounted computer. The utility model utilizes the self components of the working platform, the working arm and the like of the aerial work vehicle to set the boundary of the working area of the aerial work vehicle, and ensures that the working range of the aerial work vehicle can not exceed the upper limit and the lower limit, thereby avoiding the contact of the aerial work vehicle and the barrier; the device has simple structure, few added parts, easy construction and transformation and low cost.
Description
Technical Field
the utility model relates to a building high altitude construction technical field specifically is an overhead working truck collision device.
Background
During the construction operation process of the high-altitude operation vehicle at high altitude and the like, the operation environment is complex, and fixed obstacles such as buildings and the like are often touched within the high-altitude operation range. When the surrounding luffing angle is small, the working boom may also hit the cab or the outrigger of the device itself.
under the working condition, the operation pressure of a driver is very high, and even if the driver has rich working experience, collision is easy to occur to cause accidents.
The anti-collision device of the existing overhead working truck is generally as follows: and adding a radar and a probe, or adopting a three-dimensional laser scanning method and the like. The structure of the device is too complex, and the radar and the probe also need to be installed at multiple points and multiple angles, so that the anti-collision device is difficult to be applied in actual construction at present.
disclosure of Invention
in order to solve the technical problem, the utility model provides an aerial working car collision device.
The utility model discloses a following technical scheme realizes: an anti-collision device for an overhead working truck comprises a control device and a vehicle-mounted computer; the control device comprises an operating handle, a telescopic control valve, a rotary control valve and a variable amplitude control valve;
the device also comprises a working vehicle detection device, a display and an alarm device;
the working vehicle detection device comprises a working arm length sensor, a working arm angle sensor and a rotary encoder, wherein the working arm length sensor, the working arm angle sensor and the rotary encoder are arranged on a working arm of the working vehicle;
the working arm length sensor is connected with the vehicle-mounted computer through a CAN bus and used for detecting the telescopic length of the working arm of the working vehicle in real time and transmitting information to the vehicle-mounted computer;
the working arm angle sensor is connected with the vehicle-mounted computer through a CAN bus and used for detecting the amplitude variation angle of the working arm of the working vehicle in real time and transmitting information to the vehicle-mounted computer;
the rotary encoder is connected with the vehicle-mounted computer through a CAN bus and is used for detecting the rotary angle of the rotary body of the operation vehicle in real time and transmitting information to the vehicle-mounted computer;
the display is connected with the vehicle-mounted computer through the CAN bus and receives and displays information transmitted by the vehicle-mounted computer;
the vehicle-mounted computer is respectively connected with the telescopic control valve, the rotary control valve, the amplitude-variable control valve and the alarm device in a control mode through the CAN bus.
an anti-collision method for an overhead working truck,
Step one, data acquisition;
Before the operation of the operation vehicle, operating an operation arm of the operation vehicle through a control device, colliding with an obstacle, collecting data of the telescopic length, the amplitude variation angle and the rotation angle when colliding with the obstacle, and transmitting the data to an on-board computer;
step two, establishing a safety boundary curve;
the vehicle-mounted computer establishes an operation boundary curve according to the data collected in the first step to obtain a safety boundary curve;
Step three, detecting the real-time position of the operation vehicle;
when the operation vehicle works, the telescopic length, the amplitude variation angle and the rotation angle of the operation vehicle are detected in real time through the operation vehicle detection device, and the real-time position of the operation vehicle is obtained;
Step four, anti-collision judgment;
Comparing the real-time position of the operating vehicle in the third step with the safety boundary curve in the second step, and judging the collision trend;
when the collision tendency does not exist, the operation vehicle continues to operate;
when there is collision trend, the vehicle computer sends signal to the control device and the alarm device, the control device controls the operation vehicle and performs deceleration movement or inching according to the distance between the vehicle and the collision object, the alarm device starts to alarm, and the operation stops.
it further comprises the following steps:
step one, data acquisition;
operating the working arm to enable the working platform to approach to the corresponding position of the obstacle, and recording three parameters of the arm length L, the elevation angle alpha and the rotation angle theta of the current working arm;
The boundary point position (θ, R, H) is obtained:
θ = θ; wherein θ: the boundary point is at a horizontal plane rotation angle;
r = L cos alpha-R 0, wherein R is the distance from the gyration center to the boundary point along the direction of the working arm;
r 0, the distance from the rotation center to the rear connecting point of the working arm along the direction of the working arm;
h = L sin alpha + H 0, wherein H is the height distance of the boundary point from the ground;
h 0 height distance of the rear connecting hinge point of the working arm from the ground.
Step two, establishing a safety boundary curve;
the safety boundary curve comprises a telescopic operation boundary curve, a variable amplitude operation boundary curve and a rotary operation boundary curve;
expansion operation boundary curve:
the length of the working arm is L = (R 0 + R)/cos alpha, the height of the working arm head is H = (R 0 + R) tan alpha + H 0, the maximum extendable arm length L max corresponding to different elevation angles alpha and rotation angles theta of the working arm is calculated according to the rotation radius R and the height H zone boundary range of the collision object, and a telescopic working boundary curve is formed;
amplitude variation operation boundary curve:
determining the angle range alpha max of the amplitude of the working arm;
calculating the value of an elevation angle alpha' according to the calculation of the maximum length of the operation arm, wherein the rotation angle is the value of theta and the maximum extendable arm length L max;
when the maximum extendable arm length L max is greater than the current arm length L, amplitude variation to an elevation angle alpha 'can be performed, and then calculation and comparison are performed after amplitude variation to the elevation angle alpha';
when the maximum arm length value L max is smaller than the current arm length, then the elevation angle α ″ is the allowable amplitude range α max;
Revolving operation boundary curve:
Determining an angle range theta max of the rotation of the working arm;
Calculating a rotation angle theta' according to the calculation of the maximum length of the operation arm, wherein the elevation angle is a numerical value of L max of the maximum extendable arm length;
when the maximum extendable arm length L max is greater than the current arm length L, it may be rotated back to θ ', and then rotated back to the next angle θ' for calculation and comparison;
when the maximum arm length value L max is smaller than the current arm length, the rotation angle θ' is the allowable rotation range θ max.
Step three, detecting the real-time position of the operation vehicle;
the operating vehicle detection device detects the state parameters of the operating vehicle in real time: the arm length L, the elevation angle alpha and the rotation angle theta are set as theta;
the vehicle-mounted computer performs fitting judgment on the length, the elevation angle and the rotation angle of the operation arm according to a group of continuously detected parameters and data, and judges the action, the extending arm, the retracting arm, the upper amplitude variation, the lower amplitude variation, the left rotation, the right rotation and the static state of the operation arm at the next moment; and calculating the length L ', the elevation angle alpha ' and the rotation angle theta ' of the operation arm at the next moment.
step four, anti-collision judgment;
The anti-collision judgment comprises the operation arm stretching anti-collision, the operation arm amplitude variation anti-collision and the operation arm rotation anti-collision;
the telescopic anti-collision of the working arm:
according to the third step, if the working arm is determined to be an extension arm motion, and the arm length L 'at the next moment is detected, according to the telescopic working boundary curve, a data table of the arm length L', the maximum extendable arm length L max of the elevation angle α and the rotation angle θ can be queried, and the maximum extendable arm length at the positions of the elevation angle α and the rotation angle θ is obtained as L max;
Comparing the arm length L' at the next moment with the maximum extendable arm length L max, and according to the difference, sending a signal to a control device by the vehicle-mounted computer, wherein the control device controls the operation vehicle to normally operate, perform deceleration movement, perform inching or stop;
amplitude variation anti-collision of the working arm:
according to the third step, if the working arm is determined to be in amplitude variation motion and the elevation angle at the next time is α ″, then according to the amplitude variation working boundary curve, a data table of maximum amplitude variation α max of the arm length L, the elevation angle α and the rotation angle θ can be queried, and a maximum amplitude variation elevation angle α max at the position where the arm length L and the rotation angle θ are located is obtained;
Comparing the amplitude elevation angle alpha' with the maximum elevation angle alpha max at the next moment, and sending a signal to a control device by the vehicle-mounted computer according to the difference, wherein the control device controls the operation vehicle to normally operate, decelerate, jog or stop;
the operation arm rotates to prevent collision:
according to the third step, if the working arm is detected and judged to be in the slewing motion and the slewing angle is θ' at the next moment, according to the slewing operation boundary curve, a data table of maximum slewing θ max of the arm length L and the elevation angle α can be queried, so that the maximum slewing angle θ max at the position where the arm length is L and the elevation angle α is obtained;
and comparing the next-time rotation angle theta' with the maximum rotatable angle theta max, and sending a signal to a control device by the vehicle-mounted computer according to the difference, wherein the control device controls the operation vehicle to rotate normally, move in a decelerating manner, slightly move or stop.
compared with the prior art, the beneficial effects of the utility model are that: the working area boundary of the high-altitude operation vehicle is set by utilizing the self components of the high-altitude operation vehicle, such as the working platform, the working arm and the like, so that the working range of the high-altitude operation vehicle is ensured not to exceed the upper limit and the lower limit, and the high-altitude operation vehicle is prevented from touching the barrier; the device has simple structure, few added parts, easy construction and transformation and low cost.
Drawings
FIG. 1 is a control schematic diagram of the present invention;
FIG. 2 is a control flow chart of the present invention;
FIG. 3 is a schematic diagram of the safety margin curve established in the present invention;
fig. 4 is a schematic view of the telescopic anti-collision of the working arm of the present invention;
Fig. 5 is a schematic view of the variable-amplitude anti-collision device of the working arm of the present invention;
fig. 6 is a schematic view of the anti-collision rotation of the middle working arm of the present invention.
Detailed Description
The following is a specific embodiment of the present invention, which will be further described with reference to the accompanying drawings.
referring to fig. 1, the anti-collision device for the overhead working truck comprises a working truck detection device 1, a display 2, a control device 3, a vehicle-mounted computer 4 and an alarm device 5. The control device 3 comprises an operating handle, a telescopic control valve, a rotary control valve and a variable amplitude control valve.
The work vehicle detection device 1 includes a work arm length sensor, a work arm angle sensor, and a rotary encoder, which are mounted on a work arm of the work vehicle. The operation arm length sensor is connected with the vehicle-mounted computer 4 through a CAN bus and used for detecting the telescopic length of the operation arm of the operation vehicle in real time and transmitting information to the vehicle-mounted computer 4. The operation arm angle sensor is connected with the vehicle-mounted computer 4 through a CAN bus, and is used for detecting the amplitude variation angle of the operation arm of the operation vehicle in real time and transmitting information to the vehicle-mounted computer 4. The rotary encoder is connected with the vehicle-mounted computer 4 through a CAN bus, and is used for detecting the rotary angle of the rotary body of the operation vehicle in real time and transmitting information to the vehicle-mounted computer 4.
The vehicle-mounted computer 4 is respectively connected with the telescopic control valve, the rotary control valve, the amplitude-variable control valve and the alarm device 5 in a control mode through a CAN bus. The vehicle-mounted computer 4 establishes a collision obstacle position database and a safety boundary curve, and runs anti-collision control.
the display 2 is connected with the vehicle-mounted computer 4 through the CAN bus, and the display 2 is provided with a human-computer interaction interface and used for receiving and displaying information transmitted by the vehicle-mounted computer 4.
referring to fig. 2, an anti-collision method for an aerial cage,
step one, data acquisition;
before the operation of the operation vehicle, the operation arm of the operation vehicle is operated by the control device 3 to approach the collision obstacle, the data of the telescopic length, the amplitude variation angle and the rotation angle when the collision obstacle occurs are collected, and the data are transmitted to the vehicle-mounted computer 4;
step two, establishing a safety boundary curve;
the vehicle-mounted computer 4 establishes an operation boundary curve according to the data acquired in the step one to obtain a safety boundary curve;
Step three, detecting the real-time position of the operation vehicle;
when the operation vehicle works, the telescopic length, the amplitude variation angle and the rotation angle of the operation vehicle are detected in real time through the operation vehicle detection device 1, and the real-time position of the operation vehicle is obtained;
step four, anti-collision judgment;
comparing the real-time position of the operating vehicle in the third step with the safety boundary curve in the second step, and judging the collision trend;
When the collision tendency does not exist, the operation vehicle continues to operate;
when there is a collision trend, the vehicle-mounted computer 4 sends a signal to the control device 3 and the alarm device 5, the control device 3 controls the operation vehicle, the control device controls the operation vehicle to normally run, move in a deceleration way, slightly move or stop, and the alarm device 5 starts to give an alarm.
referring to fig. 3, the first step is specifically to collect data:
Operating the working arm to enable the working platform to approach to the corresponding position of the obstacle, and recording three parameters of the arm length L, the elevation angle alpha and the rotation angle theta of the current working arm;
the boundary point position (θ, R, H) is obtained:
θ = θ; wherein θ: the boundary point is at a horizontal plane rotation angle;
R = L cos alpha-R 0, wherein R is the distance from the gyration center to the boundary point along the direction of the working arm;
R 0, the distance from the rotation center to the rear connecting point of the working arm along the direction of the working arm;
H = L sin alpha + H 0, wherein H is the height distance of the boundary point from the ground;
H 0 height distance of the rear connecting hinge point of the working arm from the ground.
according to the shape of the obstacle, boundary points, 6 data points in the left-right direction, the front-back direction and the height direction are collected, and 4-6 data points are added for the object with the complex shape.
step two, establishing a safety boundary curve specifically comprises the following steps:
the safety boundary curve is a telescopic boundary value, an upper amplitude boundary value, a lower amplitude boundary value and a left-right rotation boundary value of the working arm of the working vehicle which are established according to the state of the obstacle. The boundary curve mainly means that the operation arm moves within a specified effective range, and collision between the operation arm and an obstacle can be effectively avoided.
The safety boundary curve comprises a telescopic operation boundary curve, a variable amplitude operation boundary curve and a rotary operation boundary curve;
Expansion operation boundary curve:
determining the maximum extendable arm length L max of the working arm, and determining the maximum extendable arm length L max when the elevation angle is alpha and the rotation angle is theta, wherein the extension lengths of the working arm are different, when the elevation angle of the working arm is alpha and the rotation angle is theta, the distance between the arm head and the rotation center is R, the length of the working arm is calculated to be L = (R 0 + R)/cos alpha, and the height of the working arm head is H = (R 0 + R) tan alpha + H 0;
amplitude variation operation boundary curve:
determining the angle range alpha max of the amplitude of the working arm;
calculating the value of an elevation angle alpha' according to the calculation of the maximum length of the operation arm, wherein the rotation angle is the value of theta and the maximum extendable arm length L max;
when the maximum extendable arm length L max is greater than the current arm length L, amplitude variation to an elevation angle alpha 'can be performed, and then calculation and comparison are performed after amplitude variation to the elevation angle alpha';
when the maximum arm length value L max is smaller than the current arm length, then the elevation angle α ″ is the allowable amplitude range α max;
Revolving operation boundary curve:
determining an angle range theta max of the rotation of the working arm;
calculating a rotation angle theta' according to the calculation of the maximum length of the operation arm, wherein the elevation angle is a numerical value of L max of the maximum extendable arm length;
when the maximum extendable arm length L max is greater than the current arm length L, it may be rotated back to θ ', and then rotated back to the next angle θ' for calculation and comparison;
when the maximum arm length value L max is smaller than the current arm length, the rotation angle θ' is the allowable rotation range θ max.
step three, the real-time position detection of the operation vehicle is specifically as follows:
the working vehicle detection device 1 detects the state parameters of the working vehicle in real time: the arm length L, the elevation angle alpha and the rotation angle theta are set as theta;
the vehicle-mounted computer 4 fits the data according to a group of continuously detected parameters to judge the length, the elevation angle and the rotation angle of the operation arm, and judges the action, the extending arm, the contracting arm, the upper amplitude variation, the lower amplitude variation, the left rotation, the right rotation and the static state of the operation arm at the next moment; and calculating the length L ', the elevation angle alpha ' and the rotation angle theta ' of the operation arm at the next moment.
Step four, the anti-collision judgment is specifically as follows:
the anti-collision judgment comprises the operation arm stretching anti-collision, the operation arm amplitude variation anti-collision and the operation arm rotation anti-collision;
As shown in fig. 4, the telescopic boom is anti-collision:
According to the third step, if the working arm is determined to be an extension arm motion, and the arm length L 'at the next moment is detected, according to the telescopic working boundary curve, the data table of the arm length L', the maximum extendable arm length L max in the states of the elevation angle α and the rotation angle θ can be queried, and the maximum extendable arm length at the positions of the elevation angle α and the rotation angle θ is obtained as L max;
Comparing the arm length L ' at the next moment with the maximum extendable arm length L max, and according to the difference between the arm lengths L ' and L ' the maximum extendable arm length, sending a signal to the control device 3 by the vehicle-mounted computer 4, wherein the control device 3 controls the work vehicle to normally operate, perform deceleration movement, jog or stop;
as shown in fig. 5, the working boom has variable amplitude and is anti-collision:
according to the third step, if the working arm is determined to be in amplitude variation motion and the elevation angle at the next time is α ″, then according to the amplitude variation working boundary curve, a data table of the maximum variable amplitude α max in the states of the arm length L, the elevation angle α and the rotation angle θ can be queried, so as to obtain the maximum variable amplitude elevation angle α max at the position where the arm length is L and the rotation angle θ;
comparing the amplitude elevation angle α 'with the maximum elevation angle α max at the next time, sending a signal to the control device 3 by the vehicle-mounted computer 4 according to the difference between the amplitude elevation angle α' and the maximum elevation angle α max, and controlling the normal operation, the deceleration motion, the inching motion or the stop of the operation vehicle by the control device 3;
as shown in fig. 6, the working arm rotates to prevent collision:
according to the third step, if the working arm is detected and judged to be in the slewing motion and the slewing angle is θ' at the next moment, according to the slewing operation boundary curve, a data table of maximum slewing θ max of the arm length L and the elevation angle α can be queried, so that the maximum slewing angle θ max at the position where the arm length is L and the elevation angle α is obtained;
the turning angle θ' at the next time is compared with the maximum turnable angle θ max, and according to the difference therebetween, the on-board computer 4 sends a signal to the control device 3, and the control device 3 controls the work vehicle to normally operate, to perform deceleration movement, to perform inching, or to stop.
Claims (1)
1. an anti-collision device of an overhead working truck comprises a control device (3) and a vehicle-mounted computer (4); the control device (3) comprises an operating handle, a telescopic control valve, a rotary control valve and a variable amplitude control valve;
The method is characterized in that:
the device also comprises a working vehicle detection device (1), a display (2) and an alarm device (5);
the working vehicle detection device (1) comprises a working arm length sensor, a working arm angle sensor and a rotary encoder, wherein the working arm length sensor, the working arm angle sensor and the rotary encoder are arranged on a working arm of a working vehicle;
the working arm length sensor is connected with the vehicle-mounted computer (4) through a CAN bus and used for detecting the telescopic length of the working arm of the working vehicle in real time and transmitting information to the vehicle-mounted computer (4);
the working arm angle sensor is connected with the vehicle-mounted computer (4) through a CAN bus and used for detecting the amplitude variation angle of the working arm of the working vehicle in real time and transmitting information to the vehicle-mounted computer (4);
the rotary encoder is connected with the vehicle-mounted computer (4) through a CAN bus and is used for detecting the rotary angle of the rotary body of the operation vehicle in real time and transmitting information to the vehicle-mounted computer (4);
the display (2) is connected with the vehicle-mounted computer (4) through the CAN bus, and the display (2) receives and displays information transmitted by the vehicle-mounted computer (4);
the vehicle-mounted computer (4) is respectively connected with the telescopic control valve, the rotary control valve, the variable amplitude control valve and the alarm device (5) in a control mode through a CAN bus.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201920567871.XU CN209758984U (en) | 2019-04-24 | 2019-04-24 | anti-collision device for overhead working truck |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201920567871.XU CN209758984U (en) | 2019-04-24 | 2019-04-24 | anti-collision device for overhead working truck |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CN209758984U true CN209758984U (en) | 2019-12-10 |
Family
ID=68760393
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN201920567871.XU Active CN209758984U (en) | 2019-04-24 | 2019-04-24 | anti-collision device for overhead working truck |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN209758984U (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN109970009A (en) * | 2019-04-24 | 2019-07-05 | 江苏建筑职业技术学院 | High-altitude operation vehicle collision prevention device and method |
-
2019
- 2019-04-24 CN CN201920567871.XU patent/CN209758984U/en active Active
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN109970009A (en) * | 2019-04-24 | 2019-07-05 | 江苏建筑职业技术学院 | High-altitude operation vehicle collision prevention device and method |
| CN109970009B (en) * | 2019-04-24 | 2024-02-23 | 江苏建筑职业技术学院 | Anti-collision device and method for overhead working truck |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| CN109970009B (en) | Anti-collision device and method for overhead working truck | |
| CN108049893B (en) | Arch frame trolley working arm anti-collision system and arch frame trolley | |
| WO2020093558A1 (en) | Engineering machine and dynamic workspace collision avoidance method, device, and system thereof | |
| EP2716821B1 (en) | Shovel provided with electric rotating device and control method therefor | |
| CN109231016B (en) | Anti-collision method for building construction tower crane | |
| CN111070212B (en) | Vehicle-mounted manipulator control system and method | |
| CN106629525B (en) | Slewing device capable of automatically limiting slewing angle of working platform and control method | |
| KR102109155B1 (en) | Apparatus and method for safety control of excavator | |
| CN109179228B (en) | Anti-collision system of building construction tower crane | |
| CN107176567B (en) | A kind of forklift door frame avoiding collision and device | |
| JP7114248B2 (en) | construction machinery | |
| CN206456430U (en) | Vehicle remote control device and automobile | |
| CN209758984U (en) | anti-collision device for overhead working truck | |
| WO2020166241A1 (en) | Monitoring device and construction machine | |
| CN111908342A (en) | Auxiliary anti-collision method and system suitable for tower crane boom | |
| KR102579791B1 (en) | construction machinery | |
| CN113463718A (en) | Anti-collision control system and control method for loader | |
| CN116514031A (en) | Arm support control method, arm support controller, arm support control system and operation machine | |
| CN111099504A (en) | Crane control method and device and vehicle | |
| CN203710582U (en) | Device for protecting operation of fire fighting truck in safe range | |
| CN108867747B (en) | Automatic return adjusting system and method for engineering machinery operation arm support and engineering machinery | |
| JPH0549600B2 (en) | ||
| CN114772473A (en) | Anti-collision detection control method and system, forklift system and forklift | |
| JPH05166089A (en) | Warning system for operating machine | |
| JP4051222B2 (en) | Boarding bridge control device and boarding bridge having the same |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| GR01 | Patent grant | ||
| GR01 | Patent grant |