Folding boom assembly control method and system, and aerial work platform and storage medium

Abstract

The present invention relates to the technical field of engineering machinery. Disclosed are a folding boom assembly control method and system, and an aerial work platform and a storage medium. The control method comprises: acquiring an absolute angle of a folding boom and an extension length of a main boom; on the basis of the absolute angle of the folding boom and the extension length of the main boom, determining a current value of an oil return proportional valve of an oil cylinder; and on the basis of the current value, controlling the actuation of the oil return proportional valve of the oil cylinder, so as to implement the variable control of an oil return amount of an oil cylinder of a boom assembly. In the present invention, on the basis of not changing electrical / hydraulic hardware configurations of the existing work platforms, a current value of an oil return proportional valve of an oil cylinder is determined by means of a detected real-time posture of a boom assembly, and then the hydraulic oil return amount of an actuating oil cylinder of the boom assembly is dynamically adjusted on the basis of the current value, thereby ensuring the stability of the boom assembly during movement, and making a luffing operation of the boom assembly safer.

Description

Articulated boom control methods, systems, aerial work platforms, and storage media Technical Field

[0001] This invention belongs to the field of engineering machinery technology, and in particular relates to a control method, system, aerial work platform and storage medium for a folding boom. Background Technology

[0002] With the increasing variety of high-altitude work scenarios, aerial work platforms with higher boom lengths and more diverse boom configurations have emerged. Currently, boom movements on articulated boom aerial work platforms are still achieved through electro-hydraulic control systems. However, as boom length increases, the smoothness of boom movement is often affected by boom posture and hydraulic oil temperature. Therefore, how to address the impact of boom deflection and changes in the load on the electro-hydraulic control system on boom control (such as vibration and impact) has become a pressing technical challenge for high-height articulated boom aerial work platforms. Specifically, boom lengths exceeding 38 meters are defined as high-meter booms, and boom lengths exceeding 46 meters are defined as ultra-high-meter booms.

[0003] In existing boom electro-hydraulic control technology, only the oil inlet of the boom cylinder is controlled by variables, while the oil return of the boom cylinder is controlled quantitatively. This means that relatively smooth boom control (i.e., no shock and vibration) can only be achieved under certain conditions (such as a certain boom posture and a certain temperature range). Under other conditions, the boom stability control effect is poor and the adaptability is poor. At the same time, the influence of hydraulic resistance caused by hydraulic oil temperature on the smooth movement of the boom is not considered in the boom control process. Summary of the Invention

[0004] The purpose of this invention is to provide a control method, system, aerial work platform, and storage medium for a folding boom, in order to solve at least one of the following problems: existing boom electro-hydraulic control technology only uses variable control for the oil inlet of the boom cylinder, while using quantitative control for the oil return of the boom cylinder, resulting in poor boom stability control and poor adaptability under certain conditions; and the problem that hydraulic oil temperature affects the smooth movement of the boom.

[0005] This invention solves the above-mentioned technical problems through the following technical solution: a folding boom control method, comprising:

[0006] Obtain the absolute angle of the articulated boom and the extension / retraction length of the main boom;

[0007] The current value of the hydraulic cylinder return proportional valve is determined based on the absolute angle of the folding arm and the extension length of the main arm.

[0008] The action of the hydraulic cylinder return proportional valve is controlled according to the current value to achieve variable control of the return oil volume of the boom hydraulic cylinder.

[0009] Further, determining the current value of the hydraulic cylinder return proportional valve based on the absolute angle of the folding arm and the extension / retraction length of the main boom includes:

[0010] If the absolute angle θ of the folding arm belongs to the first angle range and the telescopic length L of the main boom belongs to the first length range, then the current value I of the oil cylinder return proportional valve is equal to the difference between the first initial current I1 and the current adjustment value ΔI.

[0011] If the absolute angle θ of the folding arm belongs to the first angle range and the extension length L of the main boom belongs to the second length range, then the current value I of the oil cylinder return proportional valve is equal to the first initial current I1.

[0012] If the absolute angle θ of the folding arm belongs to the second angle range and the telescopic length L of the main boom belongs to the first length range, then the current value I of the oil cylinder return proportional valve is equal to the difference between the second initial current I2 and the current adjustment value ΔI.

[0013] If the absolute angle θ of the folding arm belongs to the second angle range and the extension length L of the main boom belongs to the second length range, then the current value I of the oil cylinder return proportional valve is equal to the second initial current I2.

[0014] The first angle range is [θ] mid ,θ max The second angle range is [θ]. min ,θ mid ), the first length range is [L mid ,L max The second length range is [L]. min ,L mid ), θ max θ represents the absolute angle of the maximum folding arm. min θ represents the absolute angle of the minimum folding arm. mid Represents the range of the third angle (θ) min ,θ max A value within ) L max L represents the maximum telescopic length of the boom. min L represents the minimum telescopic length of the boom. mid Indicates the third length range (L) min ,L max A certain value within ), where the first initial current I1 < the second initial current I2.

[0015] Furthermore, before controlling the operation of the hydraulic cylinder return proportional valve based on the current value, the control method further includes:

[0016] Obtain the hydraulic oil temperature;

[0017] The final current value of the cylinder return proportional valve is determined based on the hydraulic oil temperature and the current value.

[0018] The operation of the oil cylinder return proportional valve is controlled based on the final current value.

[0019] Further, determining the final current value of the cylinder return proportional valve based on the hydraulic oil temperature and the current value includes:

[0020] Determine whether the hydraulic oil temperature is greater than or equal to a temperature threshold;

[0021] If yes, then the final current value is equal to the product of the corresponding temperature compensation coefficient and the current value; if no, then the final current value is equal to the current value.

[0022] Wherein, when the absolute angle θ of the folding arm corresponding to the current value belongs to the first angle range, the temperature compensation coefficient is the first temperature compensation coefficient; when the absolute angle θ of the folding arm corresponding to the current value belongs to the second angle range, the temperature compensation coefficient is the second temperature compensation coefficient; the value range of the first temperature compensation coefficient and the second temperature compensation coefficient is (0,1).

[0023] Furthermore, before obtaining the absolute angle of the folding arm and the extension / retraction length of the main boom, the control method further includes:

[0024] Obtain the operation type of the boom handle, and determine whether it is a folding boom luffing control based on the operation type;

[0025] When the operation type is folding boom luffing control, the absolute angle of the folding boom and the extension / retraction length of the main boom are obtained.

[0026] Based on the same concept, the present invention provides a folding boom control system, comprising:

[0027] Angle detection unit is used to measure the absolute angle of the folding arm;

[0028] The length detection unit is used to measure the extension and retraction length of the main boom;

[0029] The control unit is used to determine the current value of the hydraulic cylinder return proportional valve based on the absolute angle of the boom and the extension length of the main boom, and to control the action of the hydraulic cylinder return proportional valve based on the current value, thereby realizing variable control of the return oil volume of the boom hydraulic cylinder.

[0030] Furthermore, the control unit is used to determine the current value of the hydraulic cylinder return proportional valve based on the absolute angle of the folding boom and the extension / retraction length of the main boom, specifically including:

[0031] Determine whether the absolute angle θ of the folding arm belongs to a first angle range or a second angle range, and determine whether the telescopic length L of the main arm belongs to a first length range or a second length range;

[0032] If the absolute angle θ of the folding arm belongs to the first angle range and the telescopic length L of the main boom belongs to the first length range, then the current value I of the oil cylinder return proportional valve is equal to the difference between the first initial current I1 and the current adjustment value ΔI.

[0033] If the absolute angle θ of the folding arm belongs to the first angle range and the extension length L of the main boom belongs to the second length range, then the current value I of the oil cylinder return proportional valve is equal to the first initial current I1.

[0034] If the absolute angle θ of the folding arm belongs to the second angle range and the telescopic length L of the main boom belongs to the first length range, then the current value I of the oil cylinder return proportional valve is equal to the difference between the second initial current I2 and the current adjustment value ΔI.

[0035] If the absolute angle θ of the folding arm belongs to the second angle range and the extension length L of the main boom belongs to the second length range, then the current value I of the oil cylinder return proportional valve is equal to the second initial current I2.

[0036] The first angle range is [θ] mid ,θ max The second angle range is [θ]. min ,θ mid ), the first length range is [L mid ,L max The second length range is [L]. min ,L mid ), θ max θ represents the absolute angle of the maximum folding arm. min θ represents the absolute angle of the minimum folding arm. mid Represents the range of the third angle (θ) min ,θ max A value within ) L max L represents the maximum telescopic length of the boom. min L represents the minimum telescopic length of the boom. mid Indicates the third length range (L) min ,L max A certain value within ), where the first initial current I1 < the second initial current I2.

[0037] Furthermore, the control system also includes a temperature detection unit for measuring the temperature of the hydraulic oil;

[0038] The control unit is also used to determine the final current value of the cylinder return proportional valve based on the hydraulic oil temperature and the current value, and then control the operation of the cylinder return proportional valve based on the final current value.

[0039] Furthermore, the control unit is used to determine the final current value of the cylinder return proportional valve based on the hydraulic oil temperature and the current value, specifically including:

[0040] Determine whether the hydraulic oil temperature is greater than or equal to a temperature threshold;

[0041] If yes, then the final current value is equal to the product of the corresponding temperature compensation coefficient and the current value; if no, then the final current value is equal to the current value.

[0042] Wherein, when the absolute angle θ of the folding arm corresponding to the current value belongs to the first angle range, the temperature compensation coefficient is the first temperature compensation coefficient; when the absolute angle θ of the folding arm corresponding to the current value belongs to the second angle range, the temperature compensation coefficient is the second temperature compensation coefficient; the value range of the first temperature compensation coefficient and the second temperature compensation coefficient is (0,1).

[0043] Based on the same concept, the present invention also provides a boom-type aerial work platform, the work platform including the folding boom control system described above.

[0044] Based on the same concept, the present invention also provides a computer-readable storage medium having a computer program / instructions stored thereon, which, when executed by a processor, implements the steps of the folding boom control method as described above. Beneficial effects

[0045] Compared with the prior art, the advantages of the present invention are as follows:

[0046] This invention, without altering the existing electrical / hydraulic hardware configuration of the operating platform, determines the current value of the hydraulic cylinder return proportional valve by detecting the real-time boom posture (absolute angle of the folding boom and the extension length of the main boom), and then dynamically adjusts the hydraulic return volume of the boom actuation cylinder based on this current value, ensuring the stability of the boom during operation and making boom luffing operation safer and more comfortable.

[0047] The present invention also determines the temperature compensation coefficient by detecting the hydraulic oil temperature, dynamically adjusts the current value of the cylinder return proportional valve according to the temperature compensation coefficient to obtain the final current value, and then dynamically adjusts the hydraulic return amount of the boom action cylinder according to the final current value, thereby avoiding the influence of hydraulic oil temperature on the smooth movement of the boom and further ensuring the smoothness and adaptability of boom luffing operation. Attached Figure Description

[0048] To more clearly illustrate the technical solution of the present invention, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only one embodiment of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0049] Figure 1 is a flowchart of the folding boom control method in an embodiment of the present invention;

[0050] Figure 2 is a flowchart of determining the final current value of the oil cylinder return proportional valve in an embodiment of the present invention;

[0051] Figure 3 is a structural block diagram of the articulated boom control system in an embodiment of the present invention. Detailed Implementation

[0052] The technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings of the embodiments. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0053] The technical solutions of this application will be described in detail below with specific embodiments. The following specific embodiments can be combined with each other, and the same or similar concepts or processes may not be described again in some embodiments.

[0054] As shown in Figure 1, the folding boom control method provided in this embodiment of the invention includes the following steps:

[0055] Step 1: Obtain the operation type of the boom handle;

[0056] Step 2: Determine whether the operation type of the boom handle is for folding boom luffing control; if the operation type is folding boom luffing control, proceed to step 3;

[0057] Step 3: Obtain the absolute angle of the folding boom, the extension and retraction length of the main boom, and the hydraulic oil temperature;

[0058] Step 4: Determine the current value of the hydraulic cylinder return proportional valve based on the absolute angle of the folding boom and the extension length of the main boom;

[0059] Step 5: Determine the final current value of the cylinder return proportional valve based on the hydraulic oil temperature and the current value determined in Step 4.

[0060] Step 6: Control the operation of the hydraulic cylinder return proportional valve according to the final current value determined in Step 5 to achieve variable control of the return oil volume of the boom hydraulic cylinder.

[0061] In a specific embodiment of the present invention, an angle detection unit (e.g., an angle sensor) is used to measure the absolute angle of the folding arm in real time, whereby the absolute angle of the folding arm refers to the angle between the folding arm and the horizontal plane; a length detection unit (e.g., a length sensor) is used to measure the extension and retraction length of the main boom in real time; and a temperature detection unit is used to measure the hydraulic oil temperature of the hydraulic control system in real time.

[0062] The absolute angle of the folding boom, the extension / retraction length of the main boom, and the hydraulic oil temperature are inducing factors causing boom vibration and impact. These factors are incorporated as control factors into the return oil volume control of the boom cylinder. During boom cylinder oil volume control, the angle detection unit also measures the absolute angle of the main boom and the relative angle between the main boom and the folding boom in real time, while the length detection unit measures the extension / retraction length of the folding boom in real time. The absolute angle of the main boom, the relative angle between the main boom and the folding boom, and the extension / retraction length of the folding boom are used as control factors in the boom cylinder oil volume control. Boom cylinder oil volume control is existing technology and will not be elaborated upon here. By controlling the variable oil volume of the boom cylinder and the variable oil return volume of the boom cylinder, the vibration and impact of boom movement are reduced, and the smoothness of boom movement is improved.

[0063] In a specific embodiment of the present invention, as shown in Figure 2, determining the current value of the hydraulic cylinder return proportional valve based on the absolute angle of the folding arm and the extension / retraction length of the main boom includes:

[0064] If the absolute angle θ of the folding arm belongs to the first angle range [θ] mid ,θ max Furthermore, the main boom extension length L falls within the first length range [L]. mid ,L max If the current value I of the oil cylinder return proportional valve is equal to the difference between the first initial current I1 and the current adjustment value ΔI;

[0065] If the absolute angle θ of the folding arm belongs to the first angle range [θ] mid ,θ max Furthermore, the main boom extension length L falls within the second length range [L]. min ,L mid If the current value I of the oil cylinder return proportional valve is equal to the first initial current I1;

[0066] If the absolute angle θ of the folding arm belongs to the second angle range [θ] min ,θ mid And the main boom extension length L belongs to the first length range [L] mid ,L max If the current value I of the oil cylinder return proportional valve is equal to the difference between the second initial current I2 and the current adjustment value ΔI;

[0067] If the absolute angle θ of the folding arm belongs to the second angle range [θ] min ,θ mid And the main boom extension length L belongs to the second length range [L] min ,L mid If the current value I of the oil cylinder return proportional valve is equal to the second initial current I2;

[0068] Where, θ max θ represents the absolute angle of the maximum folding arm. minθ represents the absolute angle of the minimum folding arm. mid Represents the range of the third angle (θ) min ,θ max A value within ) L max L represents the maximum telescopic length of the boom. min L represents the minimum telescopic length of the boom. mid Indicates the third length range (L) min ,L max A certain value within ), where the first initial current I1 < the second initial current I2.

[0069] In a specific embodiment of the present invention, θ mid The determination process is as follows: When the first initial current I1 and the second initial current I1 are constant, the indicators that measure the vibration performance of the folding arm (e.g., vibration frequency and / or vibration amplitude) are measured. For a certain absolute angle of the folding arm, if the vibration performance changes significantly when the angle exceeds that absolute angle, then that absolute angle of the folding arm is taken as θ. mid In this embodiment, the maximum absolute angle θ of the folding arm max The minimum absolute angle of the folding arm is θ, which is 75°. min θ is 0° mid The angle is 30–45°. L mid The determination process and θ mid The process of determining the result is similar and will not be repeated here.

[0070] The larger the absolute angle of the articulated boom, the greater the load. To make the boom start smoother (i.e., less vibration), a smaller cylinder return proportional valve current is selected. Therefore, the first initial current I1 < the second initial current I2. The first initial current I1 and the second initial current I2 are set according to technical specifications (e.g., speed requirements). In this embodiment, the values ​​of the first initial current I1 and the second initial current I2 range from 0 to 2A. The current adjustment value ΔI is used to minimize vibration of the articulated boom while meeting technical specifications. The current adjustment value ΔI is determined by measuring indicators that measure the vibration performance of the articulated boom. At the current adjustment value ΔI, the vibration of the articulated boom is minimized. In this embodiment, the value of the current adjustment value ΔI ranges from 30mA to 50mA.

[0071] In a specific embodiment of the present invention, as shown in Figure 2, the final current value I of the cylinder return proportional valve is determined based on the hydraulic oil temperature and the current value I. e Specifically, it includes:

[0072] Determine if the hydraulic oil temperature T is greater than or equal to the temperature threshold T. th ;

[0073] If so, then the final current value I e It equals the product of the corresponding temperature compensation coefficient and the current value I; otherwise, the final current value I... eIt equals the current value I.

[0074] When I = I1 - ΔI or I = I1, that is, when the absolute angle θ of the bent arm corresponding to the current value I belongs to the first angle range, the temperature compensation coefficient is the first temperature compensation coefficient K1, and T ≥ T th The final current value I at that time e =K1×I;

[0075] When I = I² - ΔI or I = I², that is, when the absolute angle θ of the bent arm corresponding to the current value I belongs to the second angle range, the temperature compensation coefficient is the second temperature compensation coefficient K², and T ≥ T. th The final current value I at that time e =K2×I. In this embodiment, the values ​​of the first temperature compensation coefficient K1 and the second temperature compensation coefficient K2 are in the range of (0,1).

[0076] The higher the temperature, the lower the viscosity coefficient of the hydraulic oil. In order to reduce vibration, the first temperature compensation coefficient K1 or the second temperature compensation coefficient K2 should be smaller, that is, closer to 0.

[0077] In existing boom electro-hydraulic control technology, the current of the cylinder return proportional valve of the boom cylinder is I = I1 or I = I2; while the current of the cylinder return proportional valve obtained by the boom control method of the present invention is I e =I1, or I e =I1-△I, or I e =K1×(I1-△I), or I e =K1×I1, or I e =I2, or I e =I2-△I, or I e =K2×(I2-△I), or I e =K2×I2, the current of different cylinder return proportional valves corresponds to different boom postures, making the boom stability control effect better and the adaptability better.

[0078] Figure 3 shows a structural block diagram of the articulated boom control system according to an embodiment of the present invention. As shown in Figure 3, the articulated boom control system provided by the present invention includes an angle detection unit, a length detection unit, a temperature detection unit, a boom operating handle, a control unit, and a hydraulic cylinder return proportional valve.

[0079] The angle detection unit is used to measure the absolute angle of the boom in real time; the length detection unit is used to measure the extension and retraction length of the main boom in real time; the temperature detection unit is used to measure the hydraulic oil temperature in real time; and the boom operating handle is used to determine the operating direction and operating range of the boom in real time.

[0080] The control unit is used to determine the operation type based on the boom's operating direction and operating range. When the operation type is boom luffing control, it receives the absolute angle of the boom measured by the angle detection unit, the boom extension length measured by the length detection unit, and the hydraulic oil temperature measured by the temperature detection unit. Based on the absolute angle of the boom and the boom extension length, it determines the current value of the cylinder return proportional valve. Based on the hydraulic oil temperature and the current value, it determines the final current value of the cylinder return proportional valve. Based on the final current value, it controls the action of the cylinder return proportional valve to control the return speed of the boom cylinders (boom luffing cylinder and extension cylinder).

[0081] In this embodiment, the control unit is the vehicle controller of the aerial work platform. The vehicle controller generates a PWM signal based on the calculated final current value of the hydraulic cylinder return proportional valve. The PWM signal is applied to the coil of the hydraulic cylinder return proportional valve, and the coil generates a current drive signal. The current drive signal drives the valve core of the hydraulic cylinder return proportional valve to move. The larger the valve core opening, the larger the hydraulic oil displacement and the faster the cylinder movement; conversely, the smaller the valve core opening, the smaller the hydraulic oil displacement and the slower the cylinder movement. By controlling the proportion of the PWM signal, the voltage across the coil of the hydraulic cylinder return proportional valve is controlled, thereby adjusting the magnitude of the current drive signal and regulating the cylinder speed.

[0082] In controlling the oil inlet flow of the boom cylinders, the actuator is the cylinder oil inlet proportional valve. The control unit generates a PWM signal based on the absolute angle of the main boom, the relative angle between the main boom and the folding boom, and the extension / retraction length of the folding boom. This PWM signal is used to control the action of the cylinder oil inlet proportional valve, thereby controlling the oil inlet speed of the boom cylinders (main boom luffing cylinder and extension / retraction cylinder). Variable oil inlet flow control of the boom cylinders is existing technology and will not be elaborated upon here.

[0083] In a specific embodiment of the present invention, the actuator further includes a hydraulic cylinder switching valve, the boom luffing includes two actions: up and down, and the boom telescopic includes two actions: extension and retraction. The control unit generates a DO control signal (switching quantity level signal) according to the operating direction of the operating handle to drive the hydraulic cylinder switching valve to actuate, so as to realize the directional drive of boom luffing and telescopic.

[0084] In the present invention, the hydraulic cylinder in the hydraulic cylinder return proportional valve, hydraulic cylinder inlet proportional valve, and hydraulic cylinder hydraulic switching valve refers to the luffing hydraulic cylinder.

[0085] In some embodiments, the folding boom control system may incorporate features of any folding boom control method in the embodiments of this application, and vice versa, which will not be elaborated here.

[0086] Although not shown, embodiments of the present invention also provide a boom-type aerial work platform, the work platform including the folding boom control system of the embodiments of this application.

[0087] Although not shown, embodiments of the present invention also provide a computer-readable storage medium having a computer program / instructions stored thereon, which, when executed by a processor, implements the steps of the folding boom control method in the embodiments of this application.

[0088] Readable storage media include both permanent and non-permanent, removable and non-removable media that can store information using any method or technology. Information can be computer-readable instructions, data structures, program modules, or other data. Examples of computer storage media include, but are not limited to, phase-change memory (PRAM), static random access memory (SRAM), dynamic random access memory (DRAM), other types of random access memory (RAM), read-only memory (ROM), electrically erasable programmable read-only memory (EEPROM), flash memory or other memory technologies, CD-ROM, digital versatile optical disc (DVD) or other optical storage, magnetic tape, disk storage or other magnetic storage devices, or any other non-transferable medium that can be used to store information accessible by a computing device. As defined herein, computer-readable media does not include transient media, such as modulated data signals and carrier waves.

[0089] The above description only discloses specific embodiments of the present invention, but the scope of protection of the present invention is not limited thereto. Any changes or modifications that can be easily conceived by those skilled in the art within the scope of the technology disclosed in the present invention should be included within the scope of protection of the present invention.

Claims

1. A method of controlling a folding jib, characterized by, The control method includes: Obtain the absolute angle of the articulated boom and the extension / retraction length of the main boom; The current value of the hydraulic cylinder return proportional valve is determined based on the absolute angle of the folding arm and the extension length of the main arm. The action of the hydraulic cylinder return proportional valve is controlled according to the current value to achieve variable control of the return oil volume of the boom hydraulic cylinder.

2. The method of claim 1, wherein, The current value of the hydraulic cylinder return proportional valve is determined based on the absolute angle of the folding arm and the extension / retraction length of the main boom, including: If the absolute angle θ of the folding arm belongs to the first angle range and the telescopic length L of the main boom belongs to the first length range, then the current value I of the oil cylinder return proportional valve is equal to the difference between the first initial current I1 and the current adjustment value ΔI. If the absolute angle θ of the folding arm belongs to the first angle range and the extension length L of the main boom belongs to the second length range, then the current value I of the oil cylinder return proportional valve is equal to the first initial current I1. If the absolute angle θ of the folding arm belongs to the second angle range and the telescopic length L of the main boom belongs to the first length range, then the current value I of the oil cylinder return proportional valve is equal to the difference between the second initial current I2 and the current adjustment value ΔI. If the absolute angle θ of the folding arm belongs to the second angle range and the extension length L of the main boom belongs to the second length range, then the current value I of the oil cylinder return proportional valve is equal to the second initial current I2. Wherein, the first angle range is [θ mid ,θ max The second angle range is [θ]. min ,θ mid The first length range is [L] mid ,L max The second length range is [L] min ,L mid ), θ max θ represents the absolute angle of the maximum folding arm. min θ represents the absolute angle of the minimum folding arm. mid Represents the range of the third angle (θ) min ,θ max A value within ) L max L represents the maximum telescopic length of the boom. min L represents the minimum telescopic length of the boom. mid Indicates the third length range (L) min ,L max A value within ) where the first initial current I1 < the second initial current I2.

3. The method of claim 2, wherein: said maximum absolute angle of the folding θ max is 75°, said minimum absolute angle of the folding θ min is 0°, θ mid is 30-45°; The values ​​of the first initial current I1 and the second initial current I2 range from 0 to 2A.

4. The method according to any one of claims 1 to 3, characterized in that Before controlling the operation of the hydraulic cylinder return proportional valve based on the current value, the control method further includes: Obtain the hydraulic oil temperature; The final current value of the cylinder return proportional valve is determined based on the hydraulic oil temperature and the current value. The operation of the oil cylinder return proportional valve is controlled based on the final current value.

5. The method of claim 4, wherein: Determining the final current value of the cylinder return proportional valve based on the hydraulic oil temperature and the current value includes: Determine whether the hydraulic oil temperature is greater than or equal to a temperature threshold; If yes, then the final current value is equal to the product of the corresponding temperature compensation coefficient and the current value; if no, then the final current value is equal to the current value. Wherein, when the absolute angle θ of the folding arm corresponding to the current value belongs to the first angle range, the temperature compensation coefficient is the first temperature compensation coefficient; when the absolute angle θ of the folding arm corresponding to the current value belongs to the second angle range, the temperature compensation coefficient is the second temperature compensation coefficient; the value range of the first temperature compensation coefficient and the second temperature compensation coefficient is (0,1).

6. The method of claim 1, wherein: Before obtaining the absolute angle of the articulated boom and the telescopic length of the main boom, the control method further includes: Obtain the operation type of the boom handle, and determine whether it is a folding boom luffing control based on the operation type; When the operation type is folding boom luffing control, the absolute angle of the folding boom and the extension / retraction length of the main boom are obtained.

7. A folding boom jib control system characterized by, The control system includes: Angle detection unit is used to measure the absolute angle of the folding arm; The length detection unit is used to measure the extension and retraction length of the main boom; The control unit is used to determine the current value of the hydraulic cylinder return proportional valve based on the absolute angle of the boom and the extension length of the main boom, and to control the action of the hydraulic cylinder return proportional valve based on the current value, thereby realizing variable control of the return oil volume of the boom hydraulic cylinder.

8. The knuckleboom arm control system of claim 7, wherein, The control unit is used to determine the current value of the hydraulic cylinder return proportional valve based on the absolute angle of the articulated boom and the extension / retraction length of the main boom, specifically including: Determine whether the absolute angle θ of the folding arm belongs to a first angle range or a second angle range, and determine whether the telescopic length L of the main arm belongs to a first length range or a second length range; If the absolute angle θ of the folding arm belongs to the first angle range and the telescopic length L of the main boom belongs to the first length range, then the current value I of the oil cylinder return proportional valve is equal to the difference between the first initial current I1 and the current adjustment value ΔI. If the absolute angle θ of the folding arm belongs to the first angle range and the extension length L of the main boom belongs to the second length range, then the current value I of the oil cylinder return proportional valve is equal to the first initial current I1. If the absolute angle θ of the folding arm belongs to the second angle range and the telescopic length L of the main boom belongs to the first length range, then the current value I of the oil cylinder return proportional valve is equal to the difference between the second initial current I2 and the current adjustment value ΔI. If the absolute angle θ of the folding arm belongs to the second angle range and the extension length L of the main boom belongs to the second length range, then the current value I of the oil cylinder return proportional valve is equal to the second initial current I2. Wherein, the first angle range is [θ mid ,θ max The second angle range is [θ]. min ,θ mid The first length range is [L] mid ,L max The second length range is [L] min ,L mid ), θ max θ represents the absolute angle of the maximum folding arm. min θ represents the absolute angle of the minimum folding arm. mid Represents the range of the third angle (θ) min ,θ max A value within ) L max L represents the maximum telescopic length of the boom. min L represents the minimum telescopic length of the boom. mid Indicates the third length range (L) min ,L max A value within ) where the first initial current I1 < the second initial current I2.

9. An aerial work platform of the boom type, characterized in that, The operating platform includes the articulated boom control system as described in claim 7 or 8.

10. A computer readable storage medium having stored thereon computer programs / instructions, characterized in that, When the computer program / instructions are executed by the processor, they implement the steps of the folding boom control method as described in any one of claims 1 to 6.

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