阅读说明：本技术 一种利用视频数据测算制动距离的起重机制动报警方法 (Crane braking alarm method for measuring and calculating braking distance by using video data ) 是由 黄赫余 宋志军 游茗粤 丁泽鹏 周健燊 陈定光 莫启安 严明锋 郭少宏 于 2019-09-16 设计创作，主要内容包括：利用视频数据测算制动距离的起重机制动报警方法过程如下：①起重机卷筒筒横截面上设定标识点A,临时点B；②测量A到B点的直线距离,作为一个固定常量参数输入至程序算法；③测量半径,作为一个固定常量参数输入至程序算法；④开启摄像头,计算机依据以上弦长+反三角函数公式计算出AB点间的弧长；⑤将AB间弧长与AB间直线距离的比值存入程序常量。作为比例标准尺,供程序算法调用,当制动器开启时,摄像机监测并记录瞬时边缘点(上述操作中A点)坐标位置,利用物体跟踪算法实时追踪边缘参考点坐标位置,多帧确定目标对象的关键点位置,再通过欧几里得距离、反三角函数计算等算法计算出弧长(即滚筒滚动的位移距离),超过指定阈值立即报警。(The crane braking alarm method for measuring and calculating the braking distance by utilizing the video data comprises the following steps: firstly, setting a mark point A and a temporary point B on the cross section of a drum of a crane drum; measuring the linear distance from the point A to the point B, and inputting the linear distance as a fixed constant parameter into a program algorithm; measuring radius, and inputting the radius as a fixed constant parameter into a program algorithm; starting the camera, and calculating the arc length between the AB points by the computer according to the chord length and the inverse trigonometric function formula; storing the ratio of the arc length between AB and the straight line distance between AB into a program constant. The device is used as a proportional standard scale for calling a program algorithm, when a brake is started, a camera monitors and records the coordinate position of an instantaneous edge point (point A in the operation), the coordinate position of an edge reference point is tracked in real time by using an object tracking algorithm, the positions of key points of a target object are determined by multiple frames, the arc length (namely the displacement distance of rolling of a roller) is calculated by algorithms such as Euclidean distance and inverse trigonometric function calculation, and an alarm is given immediately when the arc length exceeds a specified threshold value.)

1. A crane braking alarm method for measuring and calculating braking distance by using video data comprises the following data processing methods: firstly, setting a mark point A and a temporary point B on the cross section of a drum of a crane drum;

measuring the linear distance from the point A to the point B, and inputting the linear distance as a fixed constant parameter into a program algorithm;

measuring radius, and inputting the radius as a fixed constant parameter into a program algorithm;

starting the camera, and calculating the arc length between the AB points by the computer according to the chord length and the inverse trigonometric function formula;

storing the ratio of the arc length between AB and the straight line distance between AB into a program constant. And the scale is used as a scale for calling a program algorithm.

The algorithm of the program is as follows:

1. let the chord AB be L, the minor arc AB be C, and the radius OA ═ OB ═ r

2.Sin(∠AOD)＝AD/OA＝(AB/2)OA＝L/2r

3.∠AOD＝arcsin(L/2r)

∠AOB＝2∠AOD＝2arcsin(L/2r)

Making radian:

arc length C

Radius of the circle

＝∠AOB×OA

＝2arcsin(L/2r)×r

＝arcsin(L/2r)×2r

Angle system:

arc length C

Equal to (central angle/360 degree) x 2 pi x radius

＝(∠AOB/360°)×2π×OA

＝(2arcsin(L/2r)/360°)×2πr

＝arcsin(L/2r)×πr/90

And (3) actual operation: when the brake is started, the camera monitors and records the coordinate position of the instantaneous edge point (point A in the operation), the coordinate position of the edge reference point is tracked in real time by using an object tracking algorithm, and the positions of key points of the target object are determined by multiple frames. Then the arc length (namely the displacement distance of the rolling of the roller) is calculated by algorithms such as Euclidean distance and inverse trigonometric function calculation, and the alarm is given immediately when the arc length exceeds a specified threshold value.

2. The crane braking alarm method for calculating the braking distance by using the video data as claimed in claim 1, wherein the method comprises the following steps: the data processing flow is as follows: 1. and acquiring a cross section video 2 of the winding drum after braking, tracking the moving arc length of a pixel reference point in the video frame by frame, and accumulating until the last frame is finished, wherein the accumulated value is the rotating distance of the pixel reference point after braking. 3. This pixel distance is then compared with the recorded scale to obtain the actual rotation distance. 4. And if the actual rotating distance exceeds a preset alarm threshold value, alarming.

The technical field is as follows:

the invention relates to a crane braking alarm method for measuring and calculating a braking distance by using video data.

Background art:

the operation of elevator need frequently open and stop, and every pause can all be monitored by braking alarm system, and present braking alarm system all realizes the control whether safe to the elevator braking through monitoring braking distance, in case surpass braking distance, the alarm will start and send alarm signal, adopts more detection mode at present to have two kinds.

The utility model provides an utilize meter rice wheel and encoder cooperation to calculate the number of turns of hoist reel, obtain braking distance data, the phenomenon of skidding appears easily in this kind of mechanical system meter rice wheel, and the installation is maintained also not very conveniently, because the reel both ends are fluted, so meter rice wheel can only be adjacent the flat section between two recesses, but in the in-service use, the wire rope of hoisting elevator axle case can escape from the recess, can beat askew meter rice wheel.

Another way is to use six-axis gravity sensors, which can be used to measure the moving distance of the overhead travelling crane, the height of the lifting hook of the winding drum, the moving distance of the rail locomotive, etc., the sensors define the attitude of the object in space by taking gravity as an input vector, an acceleration sensor is fixed on the horizontal plane of the object, when the attitude of the object changes, the inclination angle of the equipment relative to the horizontal plane can be calculated by measuring the acceleration caused by gravity, and by analyzing the dynamic acceleration, the displacement and accumulated rotation angle algorithm can be performed after analyzing the basic data such as attitude angle, accumulated rotation angle, etc., where D: orbital displacement, C: circumference of the moving wheel, N: the number of turns is accumulated. Under the condition that the moving wheel does not determine the perimeter, the perimeter can be back calculated by measuring the track displacement and the number of accumulated turns, and the more the number of accumulated turns is, the more accurate the back calculation result is. The biggest defect of the technical scheme is that wireless power supply is achieved, the working voltage is DC3.3V-5V, the built-in lithium battery can support measurement and transmission for 1 hour, in other words, the lithium battery needs to be charged every 1 hour of working, and the lithium battery is not suitable for a production environment at all.

The invention content is as follows:

the invention aims to overcome the defects of the prior art and provide a crane braking alarm method which can accurately and reliably alarm and calculate the braking distance by using video data.

The invention aims to be realized by the following technical scheme: a crane braking alarm method for measuring and calculating braking distance by using video data comprises the following data processing processes:

firstly, setting a mark point A and a temporary point B on the cross section of a drum of a crane drum;

measuring the linear distance from the point A to the point B, and inputting the linear distance as a fixed constant parameter into a program algorithm;

measuring radius, and inputting the radius as a fixed constant parameter into a program algorithm;

starting the camera, and calculating the arc length between the AB points by the computer according to the chord length and the inverse trigonometric function formula;

storing the ratio of the arc length between AB and the straight line distance between AB into a program constant. And the scale is used as a scale for calling a program algorithm.

The algorithm of the program is as follows:

4. let the chord AB be L, the minor arc AB be C, and the radius OA ═ OB ═ r

5.Sin(∠AOD)＝AD/OA＝(AB/2)OA＝L/2r

6.∠AOD＝arcsin(L/2r)

∠AOB＝2∠AOD＝2arcsin(L/2r)

Making radian:

arc length C

Radius of the circle

＝∠AOB×OA

＝2arcsin(L/2r)×r

＝arcsin(L/2r)×2r

Angle system:

arc length C

Equal to (central angle/360 degree) x 2 pi x radius

＝(∠AOB/360°)×2π×OA

＝(2arcsin(L/2r)/360°)×2πr

＝arcsin(L/2r)×πr/90

And (3) actual operation: when the brake is started, the camera monitors and records the coordinate position of the instantaneous edge point (point A in the operation), the coordinate position of the edge reference point is tracked in real time by using an object tracking algorithm, and the positions of key points of the target object are determined by multiple frames. Then the arc length (namely the displacement distance of the rolling of the roller) is calculated by algorithms such as Euclidean distance and inverse trigonometric function calculation, and the alarm is given immediately when the arc length exceeds a specified threshold value.

The data processing flow is as follows: 1. and acquiring a cross section video 2 of the winding drum after braking, tracking the moving arc length of a pixel reference point in the video frame by frame, and accumulating until the last frame is finished, wherein the accumulated value is the rotating distance of the pixel reference point after braking. 3. This pixel distance is then compared with the recorded scale to obtain the actual rotation distance. 4. And if the actual rotating distance exceeds a preset alarm threshold value, alarming.

After adopting this technical scheme, compare with prior art, this technical scheme has following advantage: the detection process of the method is non-mechanical contact, is not influenced by the steel wire rope, does not influence the daily maintenance of the crane, has no charging problem, and is more reliable in detection and alarm.

Description of the drawings:

FIG. 1 is a data processing flow chart of a crane braking alarm method for measuring and calculating braking distance by video data according to the invention;

FIG. 2 is an explanatory diagram of a mathematical model for data processing in the crane braking alarm method for measuring and calculating braking distance by video data according to the present invention;

FIG. 3 is a diagram of an auxiliary explanation of the first embodiment of the present invention;

fig. 4 is a second auxiliary explanatory view of the first embodiment of the present invention.

The specific implementation mode is as follows:

the present technology is further described below with reference to the accompanying drawings.

The data processing flow of the embodiment is as follows: as shown in FIG. 1, 1. obtain a cross-sectional video of the reel after braking 2. track the arc length of the pixel reference point movement in the video frame by frame and accumulate until the end of the last frame, the accumulated value is the distance the pixel reference point rotates after braking. 3. This pixel distance is then compared with the recorded scale to obtain the actual rotation distance. 4. And if the actual rotating distance exceeds a preset alarm threshold value, alarming.

The data calculation formula (edge calculation (pixel tracking) and embedded computer analysis (inverse trigonometric function iterative calculation)) of the technology is as follows:

7. let the chord AB be L, the minor arc AB be C, and the radius OA ═ OB ═ r

8.Sin(∠AOD)＝AD/OA＝(AB/2)OA＝L/2r

9.∠AOD＝arcsin(L/2r)

∠AOB＝2∠AOD＝2arcsin(L/2r)

As shown in fig. 2

Making radian:

arc length C

Radius of the circle

＝∠AOB×OA

＝2arcsin(L/2r)×r

＝arcsin(L/2r)×2r

Angle system:

arc length C

Equal to (central angle/360 degree) x 2 pi x radius

＝(∠AOB/360°)×2π×OA

＝(2arcsin(L/2r)/360°)×2πr

＝arcsin(L/2r)×πr/90

And (3) actual operation:

1. setting an identification point A and a temporary point B on the cross section of the drum of the crane drum;

2. measuring the linear distance from the point A to the point B, and inputting the linear distance as a fixed constant parameter into a program algorithm;

3. measuring the radius, and inputting the radius as a fixed constant parameter into a program algorithm;

4. starting the camera, and calculating the arc length between the AB points by the computer according to the chord length and the inverse trigonometric function formula;

5. and storing the ratio of the arc length between the AB and the linear distance between the AB into a program constant. And the scale is used as a scale for calling a program algorithm.

When the brake is started, the camera monitors and records the coordinate position of the instantaneous edge point (point A in the operation), the coordinate position of the edge reference point is tracked in real time by using an object tracking algorithm, and the positions of key points of the target object are determined by multiple frames. Then the arc length (namely the displacement distance of the rolling of the roller) is calculated by algorithms such as Euclidean distance and inverse trigonometric function calculation, and the alarm is given immediately when the arc length exceeds a specified threshold value.

The calculation and execution processes will be described in detail by taking two examples of generating an alarm and not generating an alarm.

Example one, generating an alarm

Measuring the actual radius of the drum yields: 200mm

-inputting the program with the actual radius of the drum as a constant

The distance from the detected circle center to the circumference in the camera (the radius of the winding drum in the image) is as follows: 240 pixel

-inputting the program with the image radius of the web as a constant

Obtaining a pixel/mm scale: 240: 200

Namely: for every millimeter of movement of the point A on the actual reel, the point A on the screen moves by 1.2 pixels

Suppose that: the current early warning value is set to 97mm

Suppose that: establishing a plane rectangular coordinate system by taking the circle center of the cross section of the winding drum in the screen as a coordinate (0, 0)

Suppose that: when the brake brakes, the screen coordinate of the initial position A1 of the point A in the screen is recorded as (-200,133), then the winding drum cannot be immediately braked due to inertia, so the coordinate of the point A can be changed after braking, and the coordinate of the final position A2 of the point A in the screen is recorded as (230, 69) after the final picture is static

As shown in fig. 3

Long | -200 | -230| -430 px

133-69-64 px

According to a diagonal formula, the straight line distance between the position A1 and the position A2 in the screen is 435 pixels, namely, the chord length L is 435 pixels, the known radius r is 240 pixels, and the radian is arcsin (435/(2) 240) 1.134327 according to the formula of the chord length in FIG. 1

Then using radian (2 radius), the arc length is about 544 pixels

Then obtaining real A1-A2 according to the real pixel scale

685px/1.2px＝453mm

453mm is far greater than the safety braking distance 97mm of the crane drum, and an alarm is given.

Example two, No alarm is generated

Suppose that: when the brake is applied, the screen coordinate of the initial position A1 of the point A in the screen is recorded as (-200,133), and after the final picture is static, the screen coordinate of the final position A2 of the point A in the screen is recorded as (-150, 187)

Length-200- (-150) | 50px

Wide 133-

The straight-line distance (i.e., chord length) from a1 to a2 is found to be: 73.6px

According to the formula of chord length of fig. 1, radian is arcsin (73.6/(2 × 240)) -0.1539406

Using radian (2 radii) again, an arc length of about 74 pixels was obtained

Then obtaining real A1-A2 according to the real pixel scale

74px/1.2px＝62mm

62mm is less than hoist reel safety braking distance 97mm, and this braking is normal.

The foregoing is merely a preferred embodiment of the invention and is not intended to limit the invention in any manner. Those skilled in the art can make numerous possible variations and modifications to the present invention, or modify equivalent embodiments, using the methods and techniques disclosed above, without departing from the scope of the present invention. Therefore, all equivalent changes made according to the shape, structure and principle of the present invention without departing from the technical scheme of the present invention shall be covered by the protection scope of the present invention.