阅读说明：本技术 基于电磁感应原理的桥吊吊绳摆角检测装置 (Bridge crane lifting rope swing angle detection device based on electromagnetic induction principle ) 是由 刘建国 徐为民 宋贤广 刘素琪 唐辉腾 于 2021-05-17 设计创作，主要内容包括：本发明提供了一种基于电磁感应原理的桥吊吊绳摆角检测装置,包括箱体以及容置其内的第一亥姆霍兹线圈、第二亥姆霍兹线圈、第一轻质摆件、第二轻质摆件、第一固定件、第二固定件、第一线圈、第二线圈、交流电源和信号采集处理装置；第一亥姆霍兹线圈和第二亥姆霍兹线圈分别连接所述交流电源,以在各自内产生交变磁场；所述第一线圈和所述第二线圈分别与所述信号采集处理装置相连,所述信号采集处理装置用于接收所述第一线圈和所述第二线圈产生的感应电动势,并根据电磁感应原理计算所述第一线圈和所述第二线圈的转动角度,进而计算所述桥吊吊绳的摆动角度。采用不接触的测角方式,可以消除因机械磨损或环境带来的测量误差,从而有较高的精度。(The invention provides an electromagnetic induction principle-based swing angle detection device for a lifting rope of an bridge crane, which comprises a box body, a first Helmholtz coil, a second Helmholtz coil, a first light ornament, a second light ornament, a first fixing piece, a second fixing piece, a first coil, a second coil, an alternating current power supply and a signal acquisition and processing device, wherein the first Helmholtz coil, the second Helmholtz coil, the first light ornament, the second light ornament, the first fixing piece, the second fixing piece, the first coil, the second coil, the alternating current power supply and the signal acquisition and processing device are accommodated in the box body; the first Helmholtz coil and the second Helmholtz coil are respectively connected with the alternating current power supply so as to generate alternating magnetic fields in the first Helmholtz coil and the second Helmholtz coil respectively; the first coil and the second coil are respectively connected with the signal acquisition and processing device, and the signal acquisition and processing device is used for receiving induced electromotive force generated by the first coil and the second coil, calculating the rotation angle of the first coil and the second coil according to an electromagnetic induction principle, and further calculating the swing angle of the bridge crane lifting rope. By adopting a non-contact angle measurement mode, the measurement error caused by mechanical abrasion or environment can be eliminated, so that the precision is higher.)

1. A device for detecting the swing angle of a lifting rope of an bridge crane based on an electromagnetic induction principle is characterized by comprising a box body, a first Helmholtz coil, a second Helmholtz coil, a first light swing part, a second light swing part, a first fixing part, a second fixing part, a first coil, a second coil, an alternating current power supply and a signal acquisition and processing device, wherein the first Helmholtz coil, the second Helmholtz coil, the first light swing part, the second light swing part, the first fixing part, the second fixing part, the first coil, the second coil, the alternating current power supply and the signal acquisition and processing device are accommodated in the box body;

the first Helmholtz coil and the second Helmholtz coil are respectively connected with the alternating current power supply to generate alternating magnetic fields in the first Helmholtz coil and the second Helmholtz coil;

one end of the first light swing part penetrates through the box body, the other end of the first light swing part penetrates through the first fixing part and is fixedly provided with the first coil, the first coil is accommodated in the alternating magnetic field of the first Helmholtz coil, the first light swing part comprises a first swing shaft, and the extension directions of the first light swing part and the first coil are the same as the extension direction of the first swing shaft;

one end of the second light swing piece penetrates through the box body, the other end of the second light swing piece penetrates through the second fixing piece and is fixedly provided with the second coil, the second coil is contained in the alternating magnetic field of the second Helmholtz coil, the second light swing piece comprises a second swinging shaft, and the extending directions of the second light swing piece and the second coil are the same as the extending direction of the second swinging shaft;

the first light swing part and the second light swing part extend in directions perpendicular to each other, the first light swing part comprises a first groove, the second light swing part comprises a second groove, and a bridge crane lifting rope respectively penetrates through the first groove and the second groove so as to drive the first light swing part to swing in the first direction when the bridge crane lifting rope swings in the first direction; when the lifting rope of the bridge crane swings along a second direction, the second light swing part is driven to swing along the second direction; when the lifting rope of the bridge crane swings in a third direction, the first light swing part is driven to swing in the first direction, and the second light swing part swings in the second direction;

the first direction is the same as the extending direction of the second light ornament, and the second direction is the same as the extending direction of the first light ornament;

the first coil and the second coil are respectively connected with the signal acquisition and processing device, and the signal acquisition and processing device is used for receiving induced electromotive force generated by the first coil and the second coil, calculating the rotation angle of the first coil and the second coil according to an electromagnetic induction principle, and further calculating the swing angle of the bridge crane lifting rope.

2. The device for detecting the swing angle of the lifting rope of the bridge crane based on the electromagnetic induction principle as claimed in claim 1, wherein when the first light swing part and the second light swing part are at rest, the loop surfaces of the first coil and the second coil are parallel to the magnetic induction line.

3. The device for detecting the swing angle of the lifting rope of the bridge crane based on the electromagnetic induction principle as claimed in claim 1, wherein when the first light swing part and the second light swing part are at rest, the loop surfaces of the first coil and the second coil are both at a certain angle with the magnetic induction line.

4. The device for detecting the swing angle of the lifting rope of the bridge crane based on the electromagnetic induction principle as claimed in claim 2, wherein the rotation angle of the first coil or the second coil is calculated according to the electromagnetic induction principle, and the calculation formula is as follows:

dB/dt represents an alternating magnetic field magnetic induction intensity of the first helmholtz coil or the second helmholtz coil, and is the same as a current change frequency of the alternating power supply, s represents a coil segment length of a magnetic induction line cut by the first coil or the second coil, u represents an induced electromotive force of the first coil or the second coil measured by the signal acquisition processing device, and θ₁And the rotation angle of the first coil or the second coil is represented, and theta is an intermediate calculation value.

5. The device for detecting the swing angle of a lifting rope of a bridge crane based on the electromagnetic induction principle as claimed in claim 1, wherein the first light swing part is the same as the second light swing part, the first light swing part comprises a first swing part section, a second swing part section and a third swing part section, the first swing part section and the third swing part section are linear, the second swing part section is semicircular, the first swing part section is connected with one end of the second swing part section, the third swing part section is connected with the other end of the second swing part section, and the first swing part section and the second swing part section are both parallel to a tangent line of a central point of the second swing part section.

6. The device for detecting the swing angle of the suspension rope of the suspension bridge based on the electromagnetic induction principle as claimed in claim 1, wherein the first coil and the second coil are square in shape.

7. The device for detecting the swing angle of a suspension rope of a suspension bridge based on the electromagnetic induction principle as claimed in claim 4, wherein the suspension rope swings around a first swing point, the vertical distance from the first swing point to the first swing shaft is a first distance, the distance from the contact point of the suspension rope with the first light swing part when the suspension rope drives the first light swing part to swing to the first swing shaft is a second distance, and the first distance is equal to the second distance;

the vertical distance from the first swinging point to the second swinging shaft is a third distance, the distance from a contact point of the bridge crane lifting rope with the second light swing part to the second swinging shaft when the bridge crane lifting rope drives the second light swing part to swing is a fourth distance, and the third distance is equal to the fourth distance.

8. The device as claimed in claim 7, wherein the rope drives the first light swing member to swing in the first direction, and the first coil rotates at an angle θ₁According to the angle of rotation theta of the first coil₁Calculating the swing angle theta of the lifting rope of the bridge crane₂The calculation formula is as follows:

Technical Field

The invention relates to the field of container loading and unloading, in particular to a bridge crane lifting rope swing angle detection device based on an electromagnetic induction principle.

Background

Sea transport plays an important role in the logistics transportation industry, and often involves the handling of goods, i.e. containers by means of overhead cranes. The improvement of the working efficiency of the bridge crane is beneficial to improving the utilization rate of the port, thereby improving the efficiency of the whole sea transportation. The swing of the lifting rope of the bridge crane in the working process is reduced, and great help is provided for improving the working efficiency of the bridge crane.

At present, a passive anti-swing mode is mainly used for a port bridge crane, an active anti-swing technology is gradually applied to the bridge crane along with the development of a control technology, and for active anti-swing, accurate swing angle information of a lifting rope is a key for fully exerting the performance of a controller. At present, there are many devices related to the swing angle detection, for example, the swing angle measurement is performed by using the sliding rheostat principle; measuring a swing angle by using a variable capacitance principle; measuring a swing angle by using a laser mode; yaw angle measurement and the like are accomplished using methods in computer vision, both contact and non-contact are included. However, these methods have some problems, mechanical wear exists when the swing angle is measured by a contact method, the influence of environmental factors on the method using image processing is large, and the real-time performance is difficult to guarantee. These factors can cause inaccuracies in the swing angle measurement, which in turn affects the performance of the controller. The non-contact swing angle detection by using the laser machine has high detection precision and no mechanical abrasion, but the cost of the non-contact swing angle detection is obviously increased along with a precise optical device.

Therefore, it is necessary to provide a swing angle detecting device for a suspension rope of an axle crane, which has no mechanical wear, high accuracy and low cost.

Disclosure of Invention

The invention provides a bridge crane lifting rope swing angle detection device based on an electromagnetic induction principle, which does not generate mechanical wear and has the advantages of high precision and low cost.

In order to achieve the above and other related objects, the present invention provides an electromagnetic induction principle-based swing angle detection device for a lifting rope of an axle crane, including a box, and a first helmholtz coil, a second helmholtz coil, a first light swing part, a second light swing part, a first fixing part, a second fixing part, a first coil, a second coil, an ac power supply and a signal acquisition and processing device accommodated in the box;

the first Helmholtz coil and the second Helmholtz coil are respectively connected with the alternating current power supply to generate alternating magnetic fields in the first Helmholtz coil and the second Helmholtz coil;

one end of the first light swing part penetrates through the box body, the other end of the first light swing part penetrates through the first fixing part and is fixedly provided with the first coil, the first coil is accommodated in the alternating magnetic field of the first Helmholtz coil, the first light swing part comprises a first swing shaft, and the extension directions of the first light swing part and the first coil are the same as the extension direction of the first swing shaft;

one end of the second light swing piece penetrates through the box body, the other end of the second light swing piece penetrates through the second fixing piece and is fixedly provided with the second coil, the second coil is contained in the alternating magnetic field of the second Helmholtz coil, the second light swing piece comprises a second swinging shaft, and the extending directions of the second light swing piece and the second coil are the same as the extending direction of the second swinging shaft;

the first light swing part and the second light swing part extend in directions perpendicular to each other, the first light swing part comprises a first groove, the second light swing part comprises a second groove, and a bridge crane lifting rope respectively penetrates through the first groove and the second groove so as to drive the first light swing part to swing in the first direction when the bridge crane lifting rope swings in the first direction; when the lifting rope of the bridge crane swings along a second direction, the second light swing part is driven to swing along the second direction; when the lifting rope of the bridge crane swings in a third direction, the first light swing part is driven to swing in the first direction, and the second light swing part swings in the second direction;

the first direction is the same as the extending direction of the second light ornament, and the second direction is the same as the extending direction of the first light ornament;

the first coil and the second coil are respectively connected with the signal acquisition and processing device, and the signal acquisition and processing device is used for receiving induced electromotive force generated by the first coil and the second coil, calculating the rotation angle of the first coil and the second coil according to an electromagnetic induction principle, and further calculating the swing angle of the bridge crane lifting rope.

Preferably, when the first light swing part and the second light swing part are static, the coil surfaces of the first coil and the second coil are parallel to the magnetic induction line.

Preferably, when the first and second light ornament are at rest, the coil surfaces of the first and second coils are both at an angle to the magnetic induction line.

Preferably, the rotation angle of the first coil or the second coil is calculated according to the electromagnetic induction principle, and the calculation formula is as follows:

dB/dt represents an alternating magnetic field magnetic induction intensity of the first helmholtz coil or the second helmholtz coil, and is the same as a current change frequency of the alternating power supply, s represents a coil segment length of a magnetic induction line cut by the first coil or the second coil, u represents an induced electromotive force of the first coil or the second coil measured by the signal acquisition processing device, and θ₁Represents the aboveThe rotation angle of the first coil or the second coil, theta is an intermediate calculation value.

Preferably, the first light ornament is the same as the second light ornament, the first light ornament includes a first ornament section, a second ornament section and a third ornament section, the first ornament section and the third ornament section are linear, the second ornament section is semicircular, the first ornament section is connected with one end of the second ornament section, the third ornament section is connected with the other end of the second ornament section, and the first ornament section and the second ornament section are parallel to the tangent line of the center point of the second ornament section.

Preferably, the first coil and the second coil are square in shape.

Preferably, the bridge crane lifting rope swings around a first swinging point, a vertical distance from the first swinging point to the first swinging shaft is a first distance, a distance from a contact point of the bridge crane lifting rope and the first light swing piece when the bridge crane lifting rope drives the first light swing piece to swing to the first swinging shaft is a second distance, and the first distance is equal to the second distance;

the vertical distance from the first swinging point to the second swinging shaft is a third distance, the distance from a contact point of the bridge crane lifting rope with the second light swing part to the second swinging shaft when the bridge crane lifting rope drives the second light swing part to swing is a fourth distance, and the third distance is equal to the fourth distance.

Preferably, the first light swing part is driven by the lifting rope of the bridge crane to swing along the first direction, and the rotation angle of the first coil is theta₁According to the angle of rotation theta of the first coil₁Calculating the swing angle theta of the lifting rope of the bridge crane₂The calculation formula is as follows:

in summary, based on the electromagnetic induction principle and the biot-savart law, the helmholtz coil is used for generating an alternating magnetic field, based on the electromagnetic induction law, the coil placed in the magnetic field is used for generating corresponding induced electromotive force, and then measured electric signals are sent to the signal processing device, and the swing angle information of the current lifting rope can be obtained through processing and calculation; and the obtained swing angle information can be sent to an anti-swing controller for anti-swing control, and also can be sent to a display screen of a bridge crane cab for a driver to carry out reference operation.

Drawings

FIG. 1 is a schematic diagram of a double-crane bridge crane applied to a bridge crane lifting rope swing angle detection device based on an electromagnetic induction principle, provided by the invention;

fig. 2 is a schematic view of a swing angle detection device of a lifting rope of an axle crane based on an electromagnetic induction principle according to a first embodiment of the present invention;

fig. 3 is a partial schematic view of a swing angle detection device of a lifting rope of an axle crane based on an electromagnetic induction principle according to a first embodiment of the present invention;

fig. 4 is a schematic diagram illustrating a first coil swinging in a swing angle detecting device for a lifting rope of an axle crane based on an electromagnetic induction principle according to a first embodiment of the present invention;

fig. 5 is a schematic view of a magnetic field of a helmholtz coil in the device for detecting a swing angle of a lifting rope of an bridge crane based on an electromagnetic induction principle according to an embodiment of the present invention;

fig. 6 is a schematic view illustrating that a first light swing part is driven by a bridge crane lifting rope in a bridge crane lifting rope swing angle detection device based on an electromagnetic induction principle according to an embodiment of the present invention to swing in a first direction;

fig. 7 is a schematic view of a bridge crane lifting rope swinging angle detection device based on an electromagnetic induction principle according to an embodiment of the present invention, in which the bridge crane lifting rope drives a first light swinging member and a second light swinging member to swing in a third direction.

Detailed Description

The following describes in detail the swing angle detection device of a lifting rope of an axle crane based on the electromagnetic induction principle according to the present invention with reference to fig. 1 to 7 and the specific embodiments. The advantages and features of the present invention will become more apparent from the following description. It is to be noted that the drawings are in a very simplified form and are all used in a non-precise scale for the purpose of facilitating and distinctly aiding in the description of the embodiments of the present invention. To make the objects, features and advantages of the present invention comprehensible, reference is made to the accompanying drawings. It should be understood that the structures, ratios, sizes, and the like shown in the drawings and described in the specification are only used for matching with the disclosure of the specification, so as to be understood and read by those skilled in the art, and are not used to limit the implementation conditions of the present invention, so that the present invention has no technical significance, and any structural modification, ratio relationship change or size adjustment should still fall within the scope of the present invention without affecting the efficacy and the achievable purpose of the present invention.

It is noted that, herein, relational terms such as first and second, and the like may be used solely to distinguish one entity or action from another entity or action without necessarily requiring or implying any actual such relationship or order between such entities or actions. Also, the terms "comprises," "comprising," or any other variation thereof, are intended to cover a non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements does not include only those elements but may include other elements not expressly listed or inherent to such process, method, article, or apparatus. Without further limitation, an element defined by the phrase "comprising an … …" does not exclude the presence of other identical elements in a process, method, article, or apparatus that comprises the element.

In the description of the present invention, it is to be understood that the terms "center," "height," "thickness," "upper," "lower," "vertical," "horizontal," "top," "bottom," "inner," "outer," "axial," "radial," "circumferential," and the like are used in the orientations and positional relationships indicated in the drawings for convenience in describing the present invention and for simplicity in description, and are not intended to indicate or imply that the referenced devices or elements must have a particular orientation, be constructed and operated in a particular orientation, and are not to be considered limiting. In the description of the present invention, "a plurality" means two or more unless otherwise specified.

In the description of the present invention, unless otherwise expressly specified or limited, the terms "mounted," "connected," and "fixed" are to be construed broadly, e.g., as meaning either a fixed connection, a removable connection, or an integral part; can be mechanically or electrically connected; either directly or indirectly through intervening media, either internally or in any other relationship. The specific meanings of the above terms in the present invention can be understood in specific cases to those skilled in the art.

First, with reference to the helmholtz coil and the electromagnetic induction phenomenon used in the present invention, the conductor in the changing magnetic flux generates a corresponding induced electromotive force, which is called the electromagnetic induction phenomenon and is also the working principle of the generator. When the magnetic field is in a constant state, the coil moves in the magnetic field to change state, and at the moment, induced electromotive force is generated in the coil, and the magnitude u of the induced electromotive force is d phi/dt, wherein d phi is the change amount of magnetic flux. The above is the case of induced electromotive force generated by the coil when the magnetic field is constant. When the coil is in a fixed state and the magnetic field intensity changes, the magnetic flux in the coil can still be changed due to the change of the magnetic field, the condition of generating electromotive force in the coil is met, and the coil can still generate electromotive force.

The magnetic effect of the current indicates that electricity and magnetism can be mutually converted. The magnetic field can be generated around the electrified coil, the strength of the generated magnetic field is in positive correlation with the intensity of the current of the coil and the number of turns of the coil, and the magnetic field can be generated by utilizing the current magnetic effect. The number of turns of the coil is fixed, and the magnitude of the magnetic field intensity generated by the coil is only related to the current in the coil. At this time, the intensity of the magnetic field generated by the coil can be adjusted by adjusting the current flowing through the coil. According to the Bio-Saval law, the magnitude of the magnetic induction intensity d phi generated by the current element at a certain point P in space is in direct proportion to the magnitude of the current element. Based on this, can utilize a pair of coaxial circular coil that is parallel to each other and communicates, the electric current direction in two coils is unanimous, and the size is the same, can produce approximate homogeneous magnetic field in its great scope near the central point of common axis when distance d between the coil just equals circular coil's radius R, and this is helmholtz coil.

Fig. 1 is a schematic diagram of a double-crane bridge crane applied to a bridge crane lifting rope swing angle detection device based on an electromagnetic induction principle, wherein a main frame 1 of the bridge crane bears the weight of the whole bridge crane and plays a supporting role; the two winches 2 can perform lifting operation according to the command of a bridge crane driver; the pulley 3 is used for moving the trolley on the cart and can drive the winch 2 and the swing angle detection device 5 which are arranged on the trolley to move according to the operation command of a driver; the lifting rope 6 of the bridge crane is usually a steel wire rope and is wound on the winch 2; a lifting appliance 7 for grabbing the container is connected with a lifting rope 6; and the two sets of swing angle detectors 5 are arranged below the trolley and used for detecting the swing angle of the lifting rope 6.

Example one

Fig. 2 is a view of a swing angle detection device of a lifting rope of an axle crane based on an electromagnetic induction principle according to the present embodiment, referring to fig. 2, the device includes a box 10, and a first helmholtz coil 21, a second helmholtz coil 22, a first light swing part 31, a second light swing part 32, a first coil 41, a second coil 42, a first fixing part 51, a second fixing part 52, an ac power supply, and a signal acquisition and processing device accommodated in the box; the first helmholtz wire 21 and the second helmholtz coil 22 are respectively connected with an alternating current power supply to generate an alternating magnetic field in each of them; as shown in fig. 2, one end of the first light weight swing part 31 passes through the box 10, and the other end passes through the first fixing part 51 and is fixed with the first coil 41, so that the first light weight swing part 31 can swing around a shaft and has the same rotation angle as the first coil 41; the first coil 41 is accommodated in the alternating magnetic field of the first helmholtz coil 21, the first lightweight pendulum 31 includes a first swinging axis 31a, and the first lightweight pendulum 31 and the first coil 41 extend in the same direction as the first swinging axis 31 a; one end of the second light swing part 32 passes through the box body 10, and the other end passes through the second fixing part 52 and is fixed with the second coil 42, so that the second light swing part 32 can swing around a shaft and has the same rotation angle as the second coil 42; the second coil 42 is accommodated in the alternating magnetic field of the second helmholtz coil 22, the second pendulum member 32 includes a second swinging axis 32a, and the second pendulum member 32 and the second coil 42 extend in the same direction as the second swinging axis 32 a. As shown in fig. 2, the first light weight swing part 31 and the second light weight swing part 32 extend in directions perpendicular to each other, the first light weight swing part 31 includes a first groove, the second light weight swing part 32 includes a second groove, and a bridge sling passes through the first groove and the second groove, respectively, so that when the bridge sling swings in a first direction, the first light weight swing part 31 is driven to swing in the first direction; when the lifting rope of the bridge crane swings along a second direction, the second light swing part 32 is driven to swing along the second direction; when the lifting rope of the bridge crane swings in the third direction, the first light swing part 31 is driven to swing in the first direction, and the second light swing part 32 swings in the second direction; the first direction is the same as the extending direction of the second light swing part 32, and the second direction is the same as the extending direction of the first light swing part 31; the first coil 41 and the second coil 42 are respectively connected with the signal acquisition and processing device, and the signal acquisition and processing device is used for receiving induced electromotive force generated by the first coil 41 and the second coil 42, calculating a rotation angle of the first coil 41 and the second coil 42 according to an electromagnetic induction principle, and further calculating a swing angle of the bridge crane lifting rope.

In specific implementation, referring to fig. 3, the bridge crane rope runs through the first groove 31b of the first light weight swing part 31, the first direction is a direction perpendicular to the paper, when the bridge crane rope swings along the first direction, the first light weight swing part 31 is driven to swing along the first direction, the first coil 41 is located in the magnetic field of the first helmholtz coil 21The magnetic induction line of the magnetic field of the first helmholtz coil 21 is vertically downward, the coil surface of the first coil 41 is parallel to the magnetic induction line, the first helmholtz coil 21 is connected with an alternating power supply, so that an alternating magnetic field is generated in the first helmholtz coil 21, and the alternating frequency of the alternating magnetic field is the same as that of the alternating power supply. Initially, the coil surface of the first coil 41 is parallel to the magnetic induction line, and the first coil 41 does not generate induced electromotive force; referring to fig. 4, the first swing member 31 swings at a certain angle along the first direction, and the first coil 41 swings by θ₁An angle, an included angle between the first coil 41 and the horizontal direction is θ, at this time, the magnetic field is an alternating magnetic field, a magnetic flux Φ passing through the first coil 41 will change continuously and alternately with time, the first coil 41 will generate an induced electromotive force u, and according to the electromagnetic induction principle, the method includes:

φ＝Bscosθ

where s represents the length of the cut magnetically induced segment when the first coil 41 is rotated.

In this embodiment, the first coil 41 may be configured as a square, where s is a side length of the first coil 41, so that:

the magnetic induction intensity generated between the Helmholtz coils and the current flowing in the coils, the number of turns of the coils and the radius of the coils are in the following relationship:

wherein, mu₀The magnetic permeability of the vacuum is constant, N is the number of turns of the coil and is also constant, R is the radius of the coil, and I is alternating current which changes along with time. Under the condition of meeting a certain error,as shown in fig. 5, an approximately uniform magnetic field (i.e., where the induction coil should be) is generated within the (-x, x) cylindrical region, and the strength of the magnetic field within this magnetic field is related only to the magnitude of the current passing through the coil. Because the current source is an alternating current source, an alternating magnetic field alternating with the current can be generated in the Helmholtz coil, and the alternating frequency of the magnetic field is consistent with the frequency of the alternating current power supply.

Then, dB/dt can be obtained by an ac power supply, and the information collecting and processing device can obtain an angle θ by measuring the induced electromotive forces u, s generated in the first coil 41 to be known values, and finally obtain the rotation angle θ of the first coil 41₁：

In the present embodiment, the rotation angle θ of the first coil 41 is obtained₁Then according to the rotation angle theta of the first coil 41₁Calculating the swing angle theta of the lifting rope of the bridge crane₂. Referring to fig. 6, point a is a fixed point of the bridge crane sling, the bridge crane sling swings around point a, point B is a vertical projection point of the first swing shaft 31a on the paper, point C is a contact point of the bridge crane sling and the first lightweight swing part 31, and for convenience of calculation, point AB may be set to BC. As shown in fig. 6, the swing angle of the first swing member 31 along the first direction is equal to the rotation angle θ of the first coil 41₁，θ₂The swing angle of the bridge sling along the first direction is determined according to the geometrical angle relation:

therefore, the swing angle of the bridge crane lifting rope is obtained, which is a calculation principle for calculating the swing angle of the bridge crane lifting rope by an electromagnetic induction principle, and taking the first light swing part 31 swinging along the first direction as an example, the swing calculation principle of the second light swing part 32 along the second direction is the same as that described above, and details are not repeated here.

However, the bridge sling does not have to swing in the first direction or the second direction, but may swing in a third direction, which is any direction other than the first direction and the second direction. Referring to fig. 7, when the first direction is the x-axis direction and the second direction is the y-axis direction, the suspension rope swings along the third direction, and no matter which direction the suspension rope swings along the x-axis_xAnd a swing angle theta along the y-axis_yAnd theta_xAnd theta_yCan be calculated by the above calculation method and then by theta_xAnd theta_yAnd calculating the swing angle of the lifting rope of the bridge crane along the third direction.

In this embodiment, to ensure that the first light weight swing part 31 and the second light weight swing part 32 can be driven to swing along the first direction and the second direction simultaneously when the lifting rope swings along the third direction, the first light weight swing part 31 and the second light weight swing part 32 should adopt a configuration with a semicircular main body, and the first groove and the second groove are also semicircular grooves. Referring to fig. 3, the first light pendulum member 31 is identical to the second light pendulum member 32, the first light pendulum member 31 includes a first pendulum member segment, a second pendulum member segment and a third pendulum member segment, the first pendulum member segment and the third pendulum member segment are linear, the second pendulum member segment is semicircular, the first pendulum member segment is connected to one end of the second pendulum member segment, the third pendulum member segment is connected to the other end of the second pendulum member segment, and the first pendulum member segment and the second pendulum member segment are parallel to a tangent line of a center point of the second pendulum member segment.

Example two

Different from the first embodiment, in the first embodiment, the swing angle of the bridge crane lifting rope can be calculated by measuring the induced electromotive force, but the swing direction of the bridge crane lifting rope cannot be known, and the inventor researches and finds that the swing direction can be judged by setting the initial positions of the first coil 41 and the second coil 42.

Because the magnetic field is approximately even in most scope in the axis center of Helmholtz coil, the initial state is vertical when supposing that the coil is installed, the analysis is simplified, but the problem of direction can not be distinguished at this moment. For the problem of direction identification, when the lifting rope is in a static state, the included angle between the first coil 41 and the second coil 42 and the vertical direction is 45 °, so that initially, the signal collecting and processing device will test induced electromotive force, and due to the alternating magnetic field, the maximum induced electromotive force at this time is assumed to be u₁(ii) a Taking the first coil 41 as an example, the second coil 42 is the same, and when the first coil 41 rotates clockwise, the magnetic induction line passing through the first coil 41 increases, and the maximum induced electromotive force at this time is assumed to be u₂Then there is u₂＞u₁(ii) a When the first coil 41 rotates counterclockwise, the magnetic induction line passing through the first coil 41 decreases, and the maximum induced electromotive force is assumed to be u at this time₃Then there is u₃＜u₁。

Therefore, the swing direction of the first coil 41 or the second coil 42 can be obtained by comparing the maximum induced electromotive force with the initial induced electromotive force, and the calculation of the swing angle may be performed to calculate the angle difference.

The invention has the advantages that based on the electromagnetic induction principle and the Biot-Saval law, the Helmholtz coil is used for generating an alternating magnetic field, based on the electromagnetic induction law, the coil arranged in the magnetic field is used for generating corresponding induced electromotive force, then the measured electric signal is sent to the signal processing device, and the swing angle information of the current lifting rope can be obtained through processing and calculation; and the obtained swing angle information can be sent to an anti-swing controller for anti-swing control, and also can be sent to a display screen of a bridge crane cab for a driver to carry out reference operation.

While the present invention has been described in detail with reference to the preferred embodiments, it should be understood that the above description should not be taken as limiting the invention. Various modifications and alterations to this invention will become apparent to those skilled in the art upon reading the foregoing description. Accordingly, the scope of the invention should be determined from the following claims.