A method for keeping a slewing platform of a truck crane horizontal and a truck crane

Abstract

The application relates to a method for keeping a slewing platform of a truck crane horizontal and the truck crane, and the specific steps are as follows: a gyroscope is arranged on the truck crane and located on a vertical center line of an area surrounded by multiple supporting legs of the truck crane, and the initial height difference between each supporting leg and the gyroscope is 0 by default; a sensor is installed to obtain the distance H (i=1~n, n is the total number of the supporting legs) between the multiple supporting legs and the ground; the multiple supporting legs of the truck crane are controlled to be horizontally extended; the gyroscope is used to detect the inclination angle of the truck crane relative to the horizontal plane; the height difference D between the multiple supporting legs and the gyroscope is calculated; the multiple supporting legs of the truck crane are controlled to be vertically extended, the distance Z (i=1~n, n is the total number of the supporting legs) by which the multiple supporting legs are extended is determined, and D is taken as min{D}. The method provided by the application can accurately calculate the length by which the supporting legs should be extended when the truck crane is on uneven ground, ensures that the truck crane is horizontal before operation, and reduces the safety risks and hidden dangers in the operation process.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of automobile crane operation, in particular to a method for keeping the rotating platform of an automobile crane horizontal and the automobile crane. BACKGROUND

[0002] In the maintenance operation of urban substations, power supply engineering cranes are used more and more widely, and the power supply engineering crane is a kind of automobile crane. Before the operation of the automobile crane, the rotating platform (or the automobile crane itself) needs to be kept in a horizontal state. Due to uneven road surfaces, the automobile crane cannot be kept in a horizontal state before operation, and when the road surface is too uneven, the operation cannot be started directly. The automobile crane has multiple supporting legs that replace the tires to bear the pressure and help the rotating platform of the automobile crane to be horizontal.

[0003] At present, in actual operation, for a relatively serious uneven road surface (within the operable range), a worker needs to be arranged beside the automobile crane to judge the inclination degree of the automobile crane by naked eye and communicate with the driver to adjust the extension length of the supporting legs in real time. For a relatively light uneven road surface that cannot be identified by naked eye, it is assumed to be horizontal, and only the length of the supporting legs needs to be adjusted slightly in the operation project. However, no matter which judgment method is used, the automobile crane cannot be kept in a truly horizontal state, and there is a great safety hazard in the operation process under the inclined state. SUMMARY

[0004] Therefore, it is necessary to provide a method for keeping the rotating platform of an automobile crane horizontal to solve the problem of great safety hazard in the adjustment of the horizontal state of the automobile crane.

[0005] The gyroscope is arranged on the automobile crane and located on the vertical center line of the area surrounded by the multiple supporting legs of the automobile crane, and the initial height difference between each supporting leg and the gyroscope is assumed to be 0;

[0006] The sensor is installed to obtain the distance Hi (i = 1 ~ n, n is the total number of supporting legs) between the multiple supporting legs and the ground;

[0007] The multiple supporting legs of the automobile crane are controlled to extend horizontally to the left and right sides of the automobile crane;

[0008] The inclination angle of the automobile crane relative to the horizontal plane is detected by the gyroscope;

[0009] The height difference Di (i = 1 ~ n, n is the total number of supporting legs) between the multiple supporting legs and the gyroscope is calculated according to the inclination angle;

[0010] The vertical extension of the multiple outriggers of the truck crane is controlled, wherein the distance of the extension of the multiple outriggers is determined as Zi=Hi+Di-D, (i=1~n, n is the total number of the outriggers), and D=min{Di}.

[0011] In one of the embodiments, after the step of controlling the horizontal extension of the multiple outriggers of the truck crane to the left and right sides of the truck crane, and before the step of detecting the inclination angle of the truck crane relative to the horizontal plane by the gyroscope, the method further comprises:

[0012] A space rectangular coordinate system is established: the gyroscope is taken as the origin O, the X-axis and the Y-axis are established in the horizontal direction, and the Z-axis is established in the vertical direction; the inclination angle α of the truck crane relative to the XOZ plane and the inclination angle β relative to the YOZ plane are determined by the gyroscope.

[0013] In one of the embodiments, after the step of establishing a space rectangular coordinate system: the gyroscope is taken as the origin O, the X-axis and the Y-axis are established in the horizontal direction, and the Z-axis is established in the vertical direction; and the inclination angle α of the truck crane relative to the XOZ plane and the inclination angle β relative to the YOZ plane are determined by the gyroscope, and before the step of calculating the height difference Di (i=1~n, n is the total number of the outriggers) between the multiple outriggers and the gyroscope according to the inclination angles, the method further comprises: determining the X-axis distance W and the Y-axis distance S between the multiple outriggers and the gyroscope, and calculating Di=Wi*sin(α)+Si*sin(β).

[0014] In one of the embodiments, after the step of determining the distance of the extension of the multiple outriggers as Zi=Hi+Di-D, and before the step of controlling the vertical extension of the multiple outriggers of the truck crane according to Zi, the method further comprises: establishing a parameter C, and finally determining the distance of the extension of the multiple outriggers as Zi=Hi+Di-D+C.

[0015] In one of the embodiments, after the step of controlling the vertical extension of the multiple outriggers of the truck crane, wherein the distance of the extension of the multiple outriggers is determined as Zi=Hi+Di-D, (i=1~n, n is the total number of the outriggers), and D=min{Di}, the method further comprises: during the process of lifting the load by the truck crane, the change of the inclination angle of the truck crane is determined by the gyroscope, so as to obtain the change amount of Zi, and the vertical extension length of the multiple outriggers is adjusted.

[0016] In one of the embodiments, the gyroscope and the sensor are both in communication connection with the host computer, the host computer is provided with a data calculation program, so as to obtain the standard vertical extension length of the multiple outriggers in real time and make adjustment.

[0017] In one of the embodiments, the host computer is provided with an inclination angle alarm program, when the inclination angle of the truck crane is too large to work, an alarm signal will be sent out.

[0018] In one of the embodiments, during the process of lifting the load by the truck crane, the change of the inclination angle of the truck crane is determined by the gyroscope, so as to obtain the change of Zi, and then the vertical extension length of the plurality of outriggers is adjusted.

[0019] The application also provides a truck crane, which is installed with the device in the method for keeping the horizontal of the slewing platform of the truck crane in any of the above embodiments and is horizontally adjusted by the method for keeping the horizontal of the slewing platform of the truck crane in any of the above embodiments.

[0020] In one of the embodiments, the number of the outriggers of the truck crane is four.

[0021] The above method for keeping the horizontal of the slewing platform of the truck crane can accurately calculate the length of the outriggers when the truck crane is on uneven road, so as to ensure the horizontal of the slewing platform of the truck crane before operation and greatly reduce the safety risk and hidden danger during the operation. BRIEF DESCRIPTION OF DRAWINGS

[0022] Fig. 1 The flow chart of the method in one of the embodiments.

[0023] Fig. 2 The position relationship diagram of the four outriggers and the gyroscope.

[0024] Fig. 3 The distribution space diagram of the four outriggers.

[0025] The figure shows the gyroscope 100 and the outrigger 200. DETAILED DESCRIPTION

[0026] In order to make the above objects, features and advantages of the application more obvious and easy to understand, the specific embodiments of the application will be described in detail below with reference to the drawings. In the following description, a lot of specific details are set forth in order to fully understand the application. However, the application can be implemented in many other ways different from those described herein, and those skilled in the art can make similar improvements without departing from the spirit of the application, so the application is not limited by the specific embodiments disclosed below.

[0027] In the description of the application, it should be understood that, if there are these terms "center", "longitudinal", "transverse", "length", "width", "thickness", "upper", "lower", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", "counterclockwise", "axial", "radial", "circumferential" and the like, these terms indicate the orientation or positional relationship based on the orientation or positional relationship shown in the drawings, and are only for the purpose of facilitating the description of the application and simplifying the description, and do not indicate or imply that the device or element referred to must have a particular orientation, be constructed and operated in a particular orientation, and therefore cannot be understood as a limitation on the application.

[0028] In addition, if there are these terms "first", "second", these terms are only for the purpose of description, and cannot be understood as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Therefore, the features defined as "first", "second" can explicitly or implicitly include at least one of the features. In the description of the application, if the term "multiple" appears, the meaning of "multiple" is at least two, such as two, three, etc., unless otherwise explicitly specified.

[0029] In this application, unless otherwise explicitly specified and limited, if there are terms such as "mounting", "connecting", "connecting", "fixing" and the like, these terms should be broadly understood. For example, it can be fixedly connected, or it can be detachably connected, or it can be integrated; it can be mechanically connected, or it can be electrically connected; it can be directly connected, or it can be indirectly connected through an intermediate medium; it can be the internal communication of two elements or the interaction relationship between two elements, unless otherwise explicitly limited. For those skilled in the art, the specific meaning of the above terms in this application can be understood according to the specific circumstances.

[0030] In this application, unless otherwise explicitly specified and limited, if there are similar descriptions such as "first feature on or under second feature", the meaning can be that the first and second features are in direct contact, or the first and second features are indirectly in contact through an intermediate medium. Moreover, the first feature "above", "above" and "above" of the second feature can be that the first feature is directly above or obliquely above the second feature, or only indicates that the horizontal height of the first feature is higher than that of the second feature. The first feature "below", "below" and "below" of the second feature can be that the first feature is directly below or obliquely below the second feature, or only indicates that the horizontal height of the first feature is less than that of the second feature.

[0031] It is to be noted that when an element such as a layer, film, region, or substrate is referred to as being "on" another element, it can be directly on the other element or intervening elements can also be present. In addition, it is to be understood that when an element such as a layer, film, region, or substrate is referred to as being "connected", "attached", or "coupled" to another element, it can be directly connected, attached, or coupled to the other element, or intervening elements can be present. As used herein, the term "vertical", "horizontal", "up", "down", "left", "right", and the like are merely used for the purpose of illustration and do not indicate an absolute orientation.

[0032] The crane is a large multi-action hoisting machinery for lifting and transporting heavy objects vertically and horizontally. The truck crane (hereinafter referred to as the crane) is a kind of crane that travels by tires. In operation, outriggers 200 on both sides of the crane need to be extended to keep the crane stable during the entire operation process and prevent it from tipping over. The crane is generally provided with four or six outriggers 200, of course, depending on the positioning, it can also be provided with other number of outriggers 200. The outriggers 200 include horizontal extension and vertical extension. The horizontal extension is to increase the footprint of the crane, because after lifting the heavy object, the center of gravity of the crane will shift. Once it shifts out of the footprint of the crane, the crane will tip over. A large footprint will ensure that the center of gravity will not shift out. The vertical extension is to make the outriggers 200 contact the ground or even lift the tires on that side to ensure the stability of the crane in operation.

[0033] The crane has high requirements for the levelness of the road. In actual operation, for the road surface that is relatively serious (within the operable range), a worker needs to be arranged beside the truck crane to judge the inclination of the truck crane by naked eye and communicate with the driver to adjust the length of the outriggers 200 in real time. For the road surface that is not serious and cannot be identified by naked eye, it is assumed to be horizontal, and only the length of the outriggers 200 needs to be adjusted slightly in the operation project. However, no matter which judgment method is used, there is a great safety hazard.

[0034] Referring to Figs. 1-3 The present application provides a method for keeping the truck crane rotary platform horizontal (hereinafter referred to as the method). By setting up a gyroscope 100, a sensor, and other data collection devices and calculating, the inclination angle of the crane on different roads can be obtained, and the crane can be made to achieve a relatively accurate horizontal state before operation by vertically extending the outriggers 200. The specific method is as follows:

[0035] The gyroscope 100 is placed on the vertical center line of the area surrounded by the plurality of outriggers 200, and the initial height difference between each outrigger 200 and the gyroscope 100 is set to 0 by default. Here, the plurality of outriggers 200 can be 4 or 6 or more even numbers, which are symmetrically arranged on the outside of the tires on both sides of the crane, and the distance between the crane outriggers 200 is known, so the center can be accurately determined. The initial height difference is set to 0 by default, which does not mean that the actual height difference between the gyroscope 100 and each outrigger 200 is 0, but that this height difference is omitted in the subsequent calculation process.

[0036] A sensor is installed to obtain the distance Hi between the plurality of outriggers 200 and the ground (i = 1 ~ n, n is the total number of outriggers 200), assuming that the number of added outriggers 200 is 4, the distances between the 4 outriggers 200 and the ground are obtained: H1, H2, H3, H4. The following will be described taking 4 outriggers 200 as an example, and the remaining number of outriggers 200 has no essential difference from 4 outriggers 200, and the horizontal state of the crane can be realized by the method provided in the present application. In this step, a corresponding sensor such as a displacement sensor can be installed on each outrigger 200, or a sensor can be installed to simultaneously obtain the distance between the 4 outriggers 200 and the ground. Please note that the distance refers to the distance between the lower end surface of the outrigger 200 and the ground, so as to ensure that the lower end of the outrigger 200 can be supported on the ground after extending to the length of the distance.

[0037] The plurality of outriggers 200 of the truck crane are controlled to be horizontally extended to the left and right sides of the crane, and this step belongs to the prior art and will not be described here.

[0038] The inclination angle of the truck crane relative to the horizontal plane is detected by the gyroscope 100, and any angle of inclination will cause inclination relative to the vertical plane or inclination relative to the horizontal plane, so in order to facilitate the inclination angle, a space rectangular coordinate system can be established with the gyroscope 100 as the origin O, the horizontal direction as the X and Y axes, and the vertical direction as the Z axis. The inclination angles of the truck crane in the XOZ and YOZ planes are determined by the gyroscope 100, which are α and β respectively. Specifically, the length direction of the vehicle body can be taken as the X axis and the width direction of the vehicle body can be taken as the Y axis.

[0039] Specifically, the gyroscope 100 can be an inertial measurement unit (IMU), which can be used to measure the inclination angles of the crane relative to the vertical plane and the horizontal plane.

[0040] In other embodiments, any one direction can be taken as the X, Y, and Z axes, because the distances of the four outriggers 200 in the space rectangular coordinate system can be determined, and the principle is existing mathematical knowledge, which will not be described here.

[0041] Referring to Fig. 1 , according to the inclination angle, the height difference Di between the multiple outriggers 200 and the gyroscope 100 is calculated. Please note that Di here is the height difference variation when measured on uneven road, and the height difference between the lower end of the outrigger 200 and the gyroscope 100 measured on the horizontal plane is 0 by default, so it does not need to be considered in the mathematical calculation process. However, when measuring in practice or when the host computer needs to calculate the program, the height difference between the gyroscope 100 and the outrigger 200 in the vertical direction needs to be subtracted in advance.

[0042] Taking the gyroscope 100 as the origin O, the length direction of the vehicle body as the X-axis, the width direction of the vehicle body as the Y-axis, and the vertical direction as the Z-axis, the inclination angles of the truck crane in the XOZ and YOZ planes are determined by the gyroscope 100, which are α and β respectively. At this time, by determining the X-axis distance W and Y-axis distance S between the multiple outriggers 200 and the gyroscope 100, we get Di = Wi*sin(α) + Si*sin(β). Here, Di can be positive or negative. Assuming that the distance from the outrigger 200 to the ground on the horizontal road is H, Di is positive, indicating that after the outrigger 200 is extended by H, it needs to be further extended by Di. Di is negative, indicating that after the outrigger 200 is extended by H, it needs to be retracted by the absolute value of Di. Of course, after the calculation, only (H + Di) needs to be extended, without retraction. The X-axis distance W and Y-axis distance S between the multiple outriggers 200 and the gyroscope 100 can be determined from the distance between the multiple outriggers 200, which is a known quantity as the inherent data of the crane.

[0043] Control the truck crane to extend the multiple outriggers 200, where the distance of the multiple outriggers 200 is determined as Zi = Hi + Di - D, (i = 1 ~ n, n is the total number of outriggers 200), and D = min{Di}. The purpose of this step is to reduce the common stroke of the four outriggers 200 and complete the final extension action. The principle behind this is that when one of the outriggers 200 touches the ground and continues to lengthen, it will inevitably adjust the inclination angle of the entire crane, affecting the extension length of the other three outriggers 200. When the crane is stopped, without adjustment, only the four outriggers 200 need to be extended by their distance Hi from the ground. At this time, the four outriggers 200 all touch the ground, but the crane is in an inclined state, so the outrigger 200 with the longest extension length needs to be retracted, and the outrigger 200 with the shortest extension length needs to be extended. In this way, when the outriggers 200 are first extended, only the final extension length needs to be calculated, without retraction. The following is an example with a simple set of data.

[0044] Assuming that the four outriggers 200 are extended horizontally to the position, the width is 400, the length is 800, and the distribution of the four outriggers 200 is as shown in Fig. 3 The height difference between the four outriggers 200 and the gyroscope 100 is -26, -46, 46, and 26, respectively. At this time, a is about 3°, and β is about 5°. Taking D = min{Di} = -46, and substituting it into the formula Z1= H1+ D1- D, the following is obtained

[0045] The extension distance of the first outrigger 200 is Z1= H1+ 26- (-46) = H1+ 72.

[0046] The extension distance of the second outrigger 200 is Z2= H2+ 46- (-46) = H2+ 92.

[0047] The extension distance of the third outrigger 200 is Z3= H3- 46- (-46) = H3.

[0048] The extension distance of the fourth outrigger 200 is Z4= H4- 26- (-46) = H4+ 20.

[0049] From the height difference between the four outriggers 200 and the gyroscope 100, if the ground under the first outrigger 200 is taken as the reference, the height difference between the ground under the three outriggers 200 and the ground is -20, 72, and 52, respectively. Adding the distance between the first outrigger 200 and the ground to the four groups of numbers 0, -20, 72, and 52, respectively, and substituting them into H1, H2, H3, and H4, respectively, Z1= Z2= Z3= Z4 is obtained, that is, the extension lengths are equal, and the crane is kept in a horizontal state.

[0050] The above numbers do not represent the actual parameters of the crane or the specific data of the road, but are selected to illustrate that the method provided herein can achieve the corresponding technical effects. By substituting the actual parameters of the crane and the inclination angle of the crane under the corresponding road conditions into the calculation, the values are obtained, and the four outriggers 200 of the crane are extended accordingly, which can also achieve the horizontal state of the crane.

[0051] Similarly, the above data are all relative values, so it is not necessary to obtain them through a spatial rectangular coordinate system. Any spatial coordinate system can be established to obtain the above data (the relative values between any two of the four outriggers 200 and the gyroscope 100 do not change, and the coordinate positions in space will be different due to the different angles of the axes), so the process of obtaining the numbers and calculating is not limited to establishing a coordinate system, and the data calculation program of the computer can be diversified.

[0052] Since the crane is inclined at the initial state and the four outriggers 200 are extended, the crane is horizontal, so at least one tire is lifted.

[0053] In one embodiment, the method provided by the present application can further set a parameter C after calculating Zi, and finally determine the distance of the extension of the plurality of legs 200 as: Zi = Hi + Di - D + C. The purpose of setting the parameter C is to make the four legs 200 all extend by a height of C, so as to reduce the effect of the tire during pressure bearing, avoid bearing too much force during operation, and affect the pressure bearing of the legs 200 and the horizontal state of the crane. Generally, C can be between 0.05 meters and 0.15 meters. It can be determined according to specific needs.

[0054] During operation, the center of gravity will shift due to the crane lifting the load, so that the pressure bearing of the four legs 200 changes. Specifically, the legs 200 that bear more pressure will be forced to retract a small displacement amount of the cylinder. As the load moves, the center of gravity will also shift, causing the four legs 200 to change slightly relative to the extension before operation, causing the crane to be unable to stably maintain a horizontal state.

[0055] Therefore, during the process of lifting the load by the truck crane, the change in the inclination angle of the truck crane can be determined by the gyroscope 100, so as to obtain the change amount of Zi, and thus adjust the vertical extension length of the plurality of legs 200.

[0056] Since the driver is focused on lifting the load, he cannot manually adjust the extension length of the legs 200. In addition, the extension change amount of the legs 200 changes at any time, and the value is very small, so it is difficult for the driver to make accurate operations. Therefore, the gyroscope 100 and the sensor can be in communication connection with the upper computer. The upper computer can be a computer or other built-in program device. The upper computer is provided with a data calculation program, which can analyze and calculate the data transmitted by the gyroscope 100 and the sensor. Since only data reception integration and formula calculation are involved, the process is relatively simple, and the effect is very easy to achieve. Therefore, the existing program can fully realize this function, and details are not repeated here. Therefore, the upper computer can realize real-time detection of the change amount of the four legs 200 during the operation of the crane, so as to quickly calculate the extension length of the four legs 200. If it is greater than the current extension length, the legs 200 are controlled to extend. If it is less than the current extension length, the legs 200 are controlled to retract, so as to realize dynamic adjustment of the four legs 200, and ensure that the crane can also dynamically be in a horizontal state as the load moves.

[0057] In one of the embodiments, the host computer is provided with an inclination angle alarm program, which will send an alarm signal when the inclination angle of the truck crane is too large to work. The inclination angle threshold can be set in advance, such as 10°, and an alarm signal will be sent when it exceeds 10°. At this time, it means that even if the outrigger 200 is adjusted, it cannot be guaranteed to be level. For example, the outrigger 200 has reached the maximum extension length, or the outrigger 200 has reached the maximum retraction length, the tire cannot bear the pressure, and so on.

[0058] The application also provides a truck crane (hereinafter referred to as crane), which has 4 or 6 or more even outriggers 200, which are symmetrically arranged and arranged towards the two sides of the tire. Correspondingly, devices are installed on the crane, such as sensors on the outrigger 200, gyroscopes 100 on the crane, host computers, etc. Through the above method, the crane can be better maintained in a horizontal state before and during work, thereby reducing safety hazards and reducing labor costs.

[0059] The technical features of the above-mentioned embodiments can be combined arbitrarily. In order to make the description simple, all possible combinations of the technical features in the above-mentioned embodiments are not described, but as long as the combination of the technical features does not exist contradictory, it should be considered as the scope of the present application.

[0060] The above-mentioned embodiments only express several implementation manners of the present application, and the description is more specific and detailed, but it should not be understood as a limitation on the patent scope of the application. It should be pointed out that for ordinary skilled in the art, without departing from the concept of the present application, a number of modifications and improvements can be made, which are all within the protection scope of the present application. Therefore, the patent protection scope of the present application should be subject to the appended claims.

Claims

1. A method of maintaining a level of a slewing platform of a truck crane, c h a r a c t e r i s e d in that, The application relates to a method for keeping a rotary platform of a truck crane horizontal, comprising the following steps: arranging a gyroscope on the truck crane and placing the gyroscope on a vertical center line of an area surrounded by multiple outriggers of the truck crane, wherein the initial height difference between each outrigger and the gyroscope is 0 by default; installing sensors to obtain distances H (i=1~n, n is the total number of outriggers) between the multiple outriggers and the ground; controlling the multiple outriggers of the truck crane to horizontally extend to the left and right sides of the truck crane; setting up a space rectangular coordinate system: taking the gyroscope as an origin O, setting up an X axis and a Y axis in the horizontal direction, and setting up a Z axis in the vertical direction; detecting the inclination angle of the truck crane relative to the horizontal plane through the gyroscope, including judging the inclination angle alpha of the truck crane relative to the XOZ plane and the inclination angle beta of the truck crane relative to the YOZ plane through the gyroscope; determining the X axis distance W and the Y axis distance S between the multiple outriggers and the gyroscope, and calculating Di=Wi*sin (alpha) + Si*sin (beta); calculating the height difference Di (i=1~n, n is the total number of outriggers) between the multiple outriggers and the gyroscope according to the inclination angle; controlling the multiple outriggers of the truck crane to vertically extend, wherein the distance Z (i=1~n, n is the total number of outriggers) that the multiple outriggers extend is determined as Z=Hi+Di-D, and D is min{Di}. After the step of determining the distance Z (i=1~n, n is the total number of outriggers) that the multiple outriggers extend as Z=Hi+Di-D, before the step of controlling the multiple outriggers of the truck crane to vertically extend according to Z, the method further comprises: setting up a parameter C, and finally determining the distance Z (i=1~n, n is the total number of outriggers) that the multiple outriggers extend as Z=Hi+Di-D+C. After the step of controlling the multiple outriggers of the truck crane to vertically extend, wherein the distance Z (i=1~n, n is the total number of outriggers) that the multiple outriggers extend is determined as Z=Hi+Di-D, the method further comprises: during the process that the truck crane hoists a heavy object, the change of the inclination angle of the truck crane is judged through the gyroscope, so that the change amount of Z is obtained, and the vertical extension length of the multiple outriggers is adjusted. The gyroscope and the sensors are in communication connection with an upper computer, the upper computer is provided with a data calculation program, so that the standard vertical extension length of the multiple outriggers can be obtained in real time and adjusted. The upper computer is provided with an inclination angle alarm program, and an alarm signal is sent when the inclination angle of the truck crane is too large to work. After the step of, during the process that the truck crane hoists a heavy object, the change of the inclination angle of the truck crane is judged through the gyroscope, so that the change amount of Z is obtained, and the vertical extension length of the multiple outriggers is adjusted, the method further comprises: after the work is completed, the multiple outriggers are retracted. The truck crane rotary platform is provided with the equipment in the method for keeping the truck crane rotary platform horizontal according to any one of claims 1-6, and the truck crane rotary platform is operated through the method for keeping the truck crane rotary platform horizontal according to any one of claims 1-6. ​ ​ 2. A method of maintaining the level of a slewing platform of a truck crane according to claim 1, characterized in that, ​ 3. A method of maintaining a level of a slewing platform of a truck crane according to claim 1, characterized in that, ​ 4. A method of maintaining a level of a slewing platform of a truck crane according to claim 1, characterized in that, ​ 5. A method of maintaining the level of a slewing platform of a truck crane according to claim 4, characterized in that, ​ 6. A method of maintaining a level of a slewing platform of a truck crane according to claim 4, characterized in that, ​ 7. A truck crane, characterized in that ​ 8. A lorry crane according to claim 7, characterised in that The automobile crane has four outriggers.

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