Forklift and anti-rollover control method, controller and control device thereof

Abstract

The invention provides a forklift loader and an anti-rollover control method, a controller and a control device.The forklift loader comprises a boom, a handle, an engine, a hydraulic oil cylinder and an electromagnetic valve, and the electromagnetic valve is used for adjusting the retraction speed of the hydraulic oil cylinder so as to adjust the variable-amplitude descending speed of the boom. The method comprises the following steps: acquiring handle opening information of a handle, rotating speed information of an engine and arm support angle information of an arm support; determining the working condition type of the boom during amplitude-variable descending; inputting the handle opening degree information, the rotating speed information and the arm support angle information into a torque calculation model corresponding to the determined working condition type so as to determine a first difference value between the current stabilizing torque and the current tipping torque; predicting a second difference value between the stabilizing moment and the tipping moment at the next moment by using the moment calculation model; and the valve control current of the electromagnetic valve is controlled according to the change of the second difference value relative to the first difference value. According to the scheme, the feedforward prediction mode is used, the response is faster, hysteresis does not exist, and real-time anti-tipping matching can be achieved.

Description

Technical Field

[0001] The present application relates to the field of forklift operations, and in particular to an anti-rollover control method, a controller, a control device, a forklift, and a machine-readable storage medium for a forklift. Background Art

[0002] A telescopic forklift is a multi-purpose forklift with a telescopic arm and off-road performance. As it has some functions of a forklift and a crane, it has various functions. By replacing different attachments, it can perform functions such as high-altitude forklift loading, hoisting, manning, and shoveling. Its complex operating conditions put forward higher requirements on the safety and stability of the whole vehicle, especially in the process of variable amplitude lowering and boom extension. As the main arm angle decreases and the boom extends, the tipping moment of the front end of the whole machine and the stability moment of the whole vehicle are constantly changing, causing the anti-rollover stability of the whole vehicle to change dynamically. How to ensure the operating efficiency of the whole vehicle while taking safety into consideration is a technical difficulty that needs to be overcome.

[0003] In the field of non-rotating forklift loading, the general technical solution for the vehicle anti-rollover system is the force limiter system, whose principle is to detect the residual load of the rear axle in real time through the force sensor installed on the rear axle, and output the signal of the force sensor to the force limiter controller. The force limiter fits an anti-rollover curve based on the rear axle margin according to the calibrated lightest point and the heaviest point of the rear axle, and outputs the fitted anti-rollover signal according to the received real-time rear axle force sensor signal. When the output signal reaches the calibrated most dangerous working condition, the force limiter sends an action cut-off signal, thereby limiting the action in the dangerous direction. In the actual operation of the forklift, it is necessary to quickly move the goods, lift the goods up or down, or move the goods in other multiple actions. Due to the strong randomness of the load, the speed of the corresponding action varies greatly with the change of the arm length and angle, and the handle operation opening and engine speed. Therefore, when the handle opening, engine speed, load and other multiple factors are superimposed to reach the target working speed, the anti-rollover torque of the whole vehicle changes in real time, especially under the condition of large angle, full arm extension and large load. At the moment when the arm changes, the cylinder gives a starting speed, and the rollover torque increases sharply, far exceeding the rollover torque when calibrated, so the rollover occurs before the force limiter is cut off. Or under the condition of large angle, full arm extension and large load, at the moment when the amplitude changes, due to the downward acceleration of the gravitational potential energy arm and the goods, the rollover torque generated by the superimposed long lever arm will also increase sharply, causing the vehicle to roll over. The current general force limiter solution is to detect the margin of the rear axle force limit. Since it is detected during the process, it has a certain lag. The most critical thing is that when the angle is large and the load is heavy, part of the force component of the heavy load presses on the rear axle, resulting in the static force limiter detecting that the margin of the rear axle at this time is safe. The force limit value at this time may be the same as the force limit value under a light load condition, but under a heavy load condition, part of the force is also distributed to the front tipping side. At the moment of starting, this force component multiplied by the large lever arm generates a tipping torque that is much greater than the torque of the same force limit value of the light load. Therefore, the force limiter system cannot identify whether it is a heavy load or a light load. If the same speed is used to control the arm movement under the same force limit value, tipping is likely to occur. Therefore, the force limiter system is only suitable for working conditions that can only be static or slightly moved. For the actual use of forklifts, the speed requirement of the variable amplitude reduction changes in real time with the driver's operating intention, and the tipping torque changes in real time. Therefore, the traditional anti-rollover method cannot meet the requirements of anti-rollover under all working conditions, under the premise of controlling the movement speed through handles or pedals to meet the work efficiency requirements. Summary of the invention

[0004] The purpose of the embodiments of the present application is to provide an anti-rollover control method, controller, control device, forklift and machine-readable storage medium for a forklift, which can solve the problem of lag in the anti-rollover method in the prior art, use a feedforward prediction method to respond faster, and realize real-time anti-rollover matching.

[0005] In order to achieve the above-mentioned object, the first aspect of the present application provides an anti-rollover control method for a forklift, the forklift comprising a boom, a handle, an engine, a hydraulic cylinder and a solenoid valve, the solenoid valve being used to adjust the retraction speed of the hydraulic cylinder to adjust the variable amplitude descending speed of the boom, the anti-rollover control method comprising:

[0006] Obtaining the handle opening information of the handle, the speed information of the engine and the arm angle information of the arm;

[0007] Determine the type of working condition the boom is in when luffing and lowering;

[0008] Inputting the handle opening information, the rotation speed information and the boom angle information into a torque calculation model corresponding to the determined working condition type to determine a first difference between a current stabilizing torque and a current tipping torque;

[0009] Using the moment calculation model to predict a second difference between the stabilizing moment and the overturning moment at the next moment;

[0010] The valve control current of the solenoid valve is controlled according to the change of the second difference relative to the first difference.

[0011] In the embodiment of the present application, controlling the valve control current of the solenoid valve according to the change of the second difference relative to the first difference includes:

[0012] When the second difference becomes larger than the first difference, increasing the valve-controlled current; and

[0013] When the second difference becomes smaller than the first difference, the valve control current is reduced.

[0014] In the embodiment of the present application, the operating condition type is any one of the following:

[0015] The conditions include starting and accelerating the variable amplitude descent, descending at a constant speed with variable amplitude descent, and decelerating and stopping the variable amplitude descent.

[0016] In the embodiment of the present application, when the determined operating condition type is a variable amplitude descent start and acceleration operating condition:

[0017] The moment calculation model is used to predict a second difference between the stabilizing moment and the overturning moment at the next moment, including:

[0018] Determine the angular acceleration of the boom according to the handle opening information and the rotation speed information;

[0019] Predicting the boom angle at the next moment based on the current boom angle and angular acceleration of the boom;

[0020] A second difference between the tipping moment and the stabilizing moment at a next moment is predicted according to the predicted boom angle and angular acceleration.

[0021] In the embodiment of the present application, controlling the valve control current of the solenoid valve according to the change of the second difference relative to the first difference further includes:

[0022] Calculating the optimal handle opening value according to the difference between the second difference and the first difference and the predicted arm angle at the next moment;

[0023] The adjustment amount of the valve control current of the solenoid valve at the next moment is determined according to the optimal handle opening value.

[0024] In the embodiment of the present application, when the determined operating condition type is a variable amplitude descent constant speed descent condition:

[0025] The moment calculation model is used to predict a second difference between the stabilizing moment and the overturning moment at the next moment, including:

[0026] Determine the angular velocity of the boom according to the handle opening information, the speed information and the current boom angle of the boom;

[0027] Predict the boom angle at the next moment based on the current boom angle and angular velocity;

[0028] A second difference between the stabilizing moment and the overturning moment at the next moment is predicted according to the predicted boom angle.

[0029] In the embodiment of the present application, when the determined operating condition type is a variable amplitude descending deceleration stop condition:

[0030] The moment calculation model is used to predict a second difference between the stabilizing moment and the overturning moment at the next moment, including:

[0031] Determine the angular acceleration of the boom according to the handle opening information;

[0032] Predicting the boom angle at the next moment based on the current boom angle and angular acceleration of the boom;

[0033] A second difference between the stabilizing moment and the tipping moment at a next moment is predicted according to the predicted boom angle and angular acceleration.

[0034] In the embodiment of the present application, controlling the valve control current of the solenoid valve according to the change of the second difference relative to the first difference further includes:

[0035] Get the current boom angle when entering the luffing, descending, decelerating and stopping condition;

[0036] Input the current boom angle into the torque calculation model to obtain the optimal angular acceleration of the boom;

[0037] Determine the corresponding handle opening value according to the optimal angular acceleration;

[0038] The current valve control current value of the solenoid valve is determined according to the corresponding handle opening value.

[0039] In the embodiment of the present application, the torque calculation model corresponding to the variable amplitude descent start and acceleration working condition is associated with the boom angle, handle opening and engine speed;

[0040] The torque calculation model corresponding to the variable-luffing constant-speed descent condition is associated with the boom angle and handle opening;

[0041] The torque calculation model corresponding to the variable amplitude descent deceleration stop condition is associated with the boom angle and handle opening.

[0042] A second aspect of the present application provides a controller configured to execute the above-mentioned anti-rollover control method for a forklift.

[0043] The third aspect of the present application provides an anti-rollover control device for a forklift, the forklift comprising an arm, a handle, an engine, a hydraulic cylinder and a solenoid valve, the solenoid valve being used to adjust the retraction speed of the hydraulic cylinder to adjust the variable amplitude descending speed of the arm, the anti-rollover control device comprising:

[0044] an angle sensor configured to detect an angle of the boom; and

[0045] The controller described above.

[0046] A fourth aspect of the present application provides a forklift, comprising:

[0047] Boom;

[0048] handle;

[0049] engine;

[0050] Hydraulic cylinder;

[0051] A solenoid valve for adjusting the retraction speed of the hydraulic cylinder to adjust the luffing and lowering speed of the boom; and

[0052] The above-mentioned anti-rollover control device for a forklift.

[0053] A fifth aspect of the present application provides a machine-readable storage medium having instructions stored thereon, the instructions being used to enable a machine to execute the above-mentioned anti-rollover control method for a forklift.

[0054] The solution provided in the embodiment of the present application may have the following advantages:

[0055] 1. Through the anti-rollover matching strategy for different working conditions and dynamic real-time prediction of anti-rollover current control, the forklift can adjust the tipping torque and stabilizing torque in real time based on different working conditions while ensuring efficiency, thereby effectively preventing tipping.

[0056] 2. Compared with the current traditional anti-rollover system, which mostly uses force limiter force limit control, there are disadvantages such as the inability to know the actual torque and obvious hysteresis for the dynamic torque. The technical solution of this application uses a feedforward prediction method to respond faster, without hysteresis, and can achieve real-time anti-rollover matching;

[0057] 3. It can be applied to non-rotational functions, and there is no need to install a pressure sensor in the cylinder. It can be detected and controlled by pure algorithm and electronic control, which reduces costs and improves reliability.

[0058] Other features and advantages of the embodiments of the present application will be described in detail in the subsequent specific implementation section. BRIEF DESCRIPTION OF THE DRAWINGS

[0059] The accompanying drawings are used to provide a further understanding of the embodiments of the present application and constitute a part of the specification. Together with the following specific implementations, they are used to explain the embodiments of the present application, but do not constitute a limitation on the embodiments of the present application. In the accompanying drawings:

[0060] Figure 1 The structural diagram of a forklift truck to which the anti-rollover control method of an embodiment of the present application can be applied is schematically shown.

[0061] Figure 2 The flowchart of the anti-rollover control method for a forklift according to an embodiment of the present application is schematically shown.

[0062] Figure 3 The figure schematically shows the position parameter settings of various components of a forklift in the anti-rollover control method for a forklift according to an embodiment of the present application.

[0063] Figure 4 The corresponding relationship between the movement speed of the hydraulic system's boom cylinder and the actual boom movement speed in the boom-lowering constant speed descent condition in the anti-rollover control method for a forklift according to an embodiment of the present application is schematically shown. DETAILED DESCRIPTION

[0064] The specific implementation of the embodiment of the present application is described in detail below in conjunction with the accompanying drawings. It should be understood that the specific implementation described here is only used to illustrate and explain the embodiment of the present application, and is not used to limit the embodiment of the present application.

[0065] The hardware components of a general force limiter solution are a force sensor and a force limit controller. The force sensor is installed on the rear axle of the forklift. The force limiter is used to receive and calculate the rear axle signal detected by the force sensor. The force sensor detects the deformation caused by the forklift pressing on the rear axle and converts it into a digital quantity. When the rear axle is subjected to a heavy load, a large deformation will occur, and the vehicle is considered safe at this time. When the load borne by the rear axle decreases and a smaller deformation occurs, the vehicle is considered dangerous. According to the different deformations caused by the different loads applied to the rear axle, the tensile stress and compressive stress detected by the force sensor will have an obvious change trend. Finally, combined with the initial safety state and tipping state calibrated when the whole machine is offline, the force limiter system can output the percentage of rear axle safety margin in real time based on the deformation of the rear axle. When the forward tipping torque is close to the stabilizing torque, the movement in the direction of increasing dangerous torque is cut off.

[0066] The force limiter solution detects a proportional relationship between the current tipping torque and the safety torque in static state, but this will cause two problems. First, the force limiter safety margin generated by heavy load, large angle and long arm is consistent with the force limit safety margin generated by a certain working condition of light load. This is because in the working condition of heavy load and large angle, part of the gravity component of the heavy load will press down the rear axle, and the other part will press down the front. Although the forward tipping torque increases, the stabilizing torque generated by pressing on the rear axle also increases. Due to the proportional relationship between the stabilizing torque and the safety torque detected by the force limiter system, the force limit safety margin of this working condition is likely to be consistent with a certain working condition under light load. However, the tipping torque generated by heavy load is much greater than the tipping torque generated by light load, and the downward amplitude of heavy load working condition is more dangerous. The second problem is that when the static system is converted to a dynamic system, the tipping moment will suddenly change. In static state, the tipping moment generated by heavy load and light load is proportional to the stabilizing moment due to the component force of heavy load pressing on the rear axle, and the rear axle safety margin generated by the force limiter is the same, but the tipping moment generated by heavy load is much greater than the tipping moment generated by light load. When the boom begins to change its amplitude downward, the tipping moment will change. There are three sources of change: the constantly changing tipping force, the tipping lever arm that constantly changes in the dangerous direction, and the acceleration force generated by the instantaneous acceleration of the amplitude change force generated by the gravity superposition cylinder. The stabilizing moment has only two sources: the change of the stabilizing lever arm and the change of the stabilizing force. Therefore, when the static system is converted to a dynamic system, if the initial speed given by the operating handle is very large, the acceleration force generated by the instantaneous acceleration generated by the gravity superposition cylinder will increase instantly. The tipping moment generated by the instantaneous increase in force multiplied by the long lever arm cannot be offset by the stabilizing moment. Because the stabilizing moment is aimed at the frame, which is a static object, there is no acceleration force involved in the balance. Therefore, it is very likely that the force limiter is safe when static under heavy load. However, once the amplitude starts to change downward, overturning will occur immediately, and the force limiter will not be cut off in time.

[0067] Based on the above analysis, it can be seen that the force limiter system cannot detect the real-time torque and the trend of torque change, so it is only suitable for static systems and micro-motion systems. However, the non-rotating forklift loading process is a multi-load process, and the speed changes in real time based on driving requirements. The force limiter system is difficult to meet the needs of all working conditions.

[0068] In view of the shortcomings of traditional anti-rollover solutions, the embodiment of the present application proposes an intelligent anti-rollover solution for forklifts based on real-time prediction of dynamic loads. The main inventive concept may be to establish a real-time torque matching algorithm based on multi-parameter input to calculate the current rollover torque and stabilizing torque, and then simulate and calculate the rollover torque and stabilizing torque at the next moment according to driving requirements, to achieve real-time prediction of the rollover torque and stabilizing torque, and based on the current torque and the torque at the next moment, adjust the action current of the amplitude reduction in real time, so that during the amplitude reduction process, the rollover torque is always smaller than the stabilizing torque, thereby solving the problem that the current force limiter system cannot detect the trend of real-time torque and torque change, resulting in a delayed rollover response.

[0069] Figure 1 The structure diagram of a forklift truck to which the anti-rollover control method of the embodiment of the present application can be applied is schematically shown. Figure 1As shown, the forklift may include a vehicle body, a boom, a hydraulic system, a controller, a handle and an accelerator pedal. One end (tail) of the boom is mounted on the rear axle of the vehicle body, and the hydraulic system may include an engine, a hydraulic pump and a hydraulic cylinder. The engine is used to drive the hydraulic pump to rotate, and the hydraulic pump pumps the hydraulic oil to the hydraulic cylinder to drive the piston rod of the hydraulic cylinder to extend and retract, thereby driving the boom to perform a variable amplitude movement (e.g., variable amplitude rise, variable amplitude fall). The hydraulic system may also include a hydraulic valve group, and the hydraulic valve group may include, for example, a boom lowering solenoid valve (e.g., an electromagnetic proportional valve) for adjusting the hydraulic oil flow of the hydraulic cylinder to adjust the speed of the boom variable amplitude fall. The handle is used to set the variable amplitude direction and variable amplitude speed of the boom. For example, the operator determines the variable amplitude direction of the boom by operating the handle to move in different directions (e.g., forward, backward, and backward), and sets the target variable amplitude speed (given speed) of the boom by operating the handle to move in different directions (e.g., forward, backward, and backward), and sets the target variable amplitude speed (given speed) of the boom by operating the handle to move in different directions (e.g., forward, backward, and backward). The accelerator pedal is used to set the engine speed. Specifically, the stroke of the accelerator pedal being stepped on (or the accelerator pedal opening) is used to set the engine speed (given speed). The forklift may also include a fork and a connecting device connecting the fork to the other end (head) of the boom. The forklift may also include a force limiter system and various sensors. The force limiter system may include a force limiter controller and a force sensor. The force sensor may be used to detect the load applied to the rear axle. In an alternative embodiment of the present application, the sensor may include another force sensor for detecting the load at the fork. The sensor may also include an angle sensor for detecting the angle of the boom (for example, relative to the horizontal plane). Since the angle of the boom corresponds to the piston rod of the hydraulic cylinder, in an alternative embodiment of the present application, the sensor may also include an angle sensor for detecting the angle of the piston rod. In an example in which the boom of the forklift is a telescopic boom, the hydraulic system may also include another hydraulic cylinder for driving the boom to perform telescopic movement, and the hydraulic valve group may include a boom extension solenoid valve for adjusting the speed of the boom extension, and a boom retraction solenoid valve for adjusting the speed of the boom retraction. The engine may be provided with an engine ECU for controlling the operation of the engine. The controller may include an industrial controller, the controller may be a vehicle controller of the forklift, or a separate controller may be provided in addition to the vehicle controller. The forklift truck may further include a display for displaying the working condition and related parameters of the forklift truck.

[0070] Those skilled in the art will appreciate that, although the embodiments of the present application are described using a forklift as an example, other working machines with booms that encounter similar problems as the forklift are also applicable.

[0071] As the general inventive concept of the embodiment of the present application, an intelligent anti-rollover technology for forklifts based on real-time prediction of dynamic load is provided. The controller can determine the anti-rollover working mode of the whole vehicle by receiving the signal of the handle based on the handle control logic. The anti-rollover working mode can include three different stages of anti-rollover working modes, which can be divided into the working condition of the boom variable amplitude descent starting and accelerating to a constant speed, the boom constant speed descent working condition, and the boom deceleration stop working condition. The controller can obtain parameters such as different boom angles, cylinder angles, boom lengths, rear axle margin percentages, handle target movement speeds, etc. for each working condition, and establish a mathematical model of the rollover torque and stabilizing torque corresponding to the current working condition based on the data collected by the sensor, and then calculate the rollover torque and stabilizing torque at the next moment according to the numerical relationship between the angle, handle opening, and accelerator pedal opening. Based on the above calculation, the current tipping torque and stabilizing torque difference and the tipping torque and stabilizing torque difference of each anti-tipping working mode are obtained, and the current closed-loop control is performed until the currently required tipping torque and stabilizing torque are within a certain range, and the current tipping torque and stabilizing torque, the maximum current that can be achieved under the current working condition, and the current working current can be displayed in real time on the display screen. The intelligent anti-tipping technology for forklifts based on real-time prediction of dynamic load proposed in this application uses an algorithm to perform specific analysis and prediction of all working conditions, covering all tipping working stages of forklifts. For different working modes, the real-time tipping torque and stabilizing torque are calculated based on the change of parameters, and the tipping torque and stabilizing torque at the next moment are calculated. Under the premise of ensuring that its efficiency is met, the safety of the whole vehicle is improved, and the problem that the traditional force limiter system cannot detect dynamic overload and real-time torque is further optimized, and the tipping problem caused by the sudden change of real-time torque caused by dynamic overload is solved, thereby improving the safety performance of the whole vehicle.

[0072] Figure 2 The flowchart of the anti-rollover control method for a forklift according to an embodiment of the present application is schematically shown. The forklift may include a boom, a handle, an engine, a hydraulic cylinder, and a solenoid valve. The solenoid valve may be used to adjust the retraction speed of the hydraulic cylinder to adjust the boom's variable amplitude lowering speed. Figure 2 In an embodiment of the present application, the anti-rollover control method may include the following steps.

[0073] In step S10, the handle opening information of the handle, the speed information of the engine and the arm angle information of the arm are obtained;

[0074] In step S20, the type of working condition of the boom during the luffing and lowering is determined;

[0075] In step S30, the handle opening information, the rotation speed information and the boom angle information are input into a torque calculation model corresponding to the determined working condition type to determine a first difference between a current stabilizing torque and a current tipping torque;

[0076] In step S40, a second difference between the stabilizing moment and the overturning moment at the next moment is predicted using the moment calculation model;

[0077] In step S50, the valve control current of the solenoid valve is controlled according to the change of the second difference relative to the first difference.

[0078] Figure 3 The figure schematically shows the position parameter settings of various components of a forklift in the anti-rollover control method for a forklift according to an embodiment of the present application. Figure 3 Specifically, in the embodiment of the present application, based on the handle action, the forklift loading action can perform three anti-rollover working mode control logics, the boom variable amplitude lowering start acceleration working condition, the boom variable amplitude lowering constant speed descending working condition, and the boom variable amplitude lowering deceleration stop working condition. Each working mode can have an anti-rollover matching algorithm that matches it. The vehicle controller can obtain the following parameters: boom angle sensor value θ1, cylinder angle value θ2, boom length L, force limiter rear axle margin I, handle opening H, accelerator pedal opening A, stabilizing force arm center of gravity S1, first arm force arm center of gravity S2, second arm force arm center of gravity S3, load center of gravity S4, stabilizing force arm L1, first arm force arm L2, second arm force arm L3, load combined force arm L4. According to the vehicle efficiency calculation, the maximum arm amplitude change speed V1 that the arm can reach and the maximum telescopic speed V2 that the arm can reach when the arm is in position Si can be obtained; based on the above parameters, the rollover torque and stability torque of the three anti-rollover working modes are calculated respectively, and the required working speed at the next moment is calculated by the handle opening and the accelerator pedal opening, and the instantaneous acceleration is obtained based on the required working speed to further obtain the rollover torque and stability torque obtained at the acceleration moment, as well as the maximum rollover torque and stability torque allowed under the current working conditions, and the maximum safe movement speed V1safemax, V2safemax of the whole vehicle is achieved by controlling the current control of the amplitude change and telescopic valves, thereby realizing the real-time anti-rollover function of the whole vehicle while ensuring work efficiency.

[0079] In the embodiment of the present application, the vehicle can calculate the force in the tipping direction and the force in the stabilizing direction through the boom angle and the cylinder angle, and then calculate the moment in the tipping direction and the moment in the stabilizing direction. During the boom's variable-length lowering movement, the angle of the variable-length cylinder changes with the change in the boom's variable-length angle. Therefore, each boom angle θ1 has a corresponding cylinder angle θ2. Through actual testing, the matching relationship between the full-operating angle of the boom and the full-operating angle of the cylinder can be obtained. The cylinder angle θ2 can be replaced by the following mathematical model;

[0080] θ2=f(θ1)

[0081] Where θ1 is the input parameter of the boom angle sensor. Here, the cylinder angle θ2 can be the angle between the cylinder piston rod and the boom, and of course, the angle between the cylinder piston rod and other reference objects (such as a horizontal plane) is also feasible.

[0082] The actual load of the object on the forklift can be measured using a force sensor installed at the fork, for example, or can be obtained through a force limiter system. Specifically, the force limiter system can obtain the real-time rear axle margin percentage, and calculate the load based on the rear axle margin percentage and the moment balance. After obtaining the load, for example, the controller can calculate the forward tipping moment and stabilizing moment of each arm section, as well as the tipping moment of the heavy object at the front end of the fork, and then convert it into the actual load relationship at the front end of the fork. Figure 3 Taking the forklift shown in the figure as an example, the boom includes two sections of the boom. Based on the mapping relationship between the boom angle and the cylinder angle and the rear axle margin percentage output by the force limiter, the boom amplitude reduction tipping moment M can be calculated. 倾翻 and stabilizing moment M 稳定 The corresponding relationship is as follows:

[0083]

[0084] Where: Km is the load weight, K 2 m is the weight of the first boom section, K 3 m is the weight of the second boom, K 车 m is the weight of the vehicle itself, L 轮 is the distance between the front and rear wheels, L k2 is the length of the first boom section, L k3 is the length of the second boom, L 连 is the length of the boom head connection device, L 货 is the length of the fork, L 1 is the length of the stabilizing force arm, L 2 is the length of the first arm moment arm, L 3 is the length of the second arm moment arm, L 4 is the load arm length.

[0085] Based on the above formula, the tipping moment M in static state can be obtained. 倾翻 and stabilizing moment M 稳定 :

[0086] M 倾翻 =F S4 ·L 4 +F S3 ·L 3

[0087] M 稳定 =F S1 ·L 1 +F S2 ·L 2

[0088] Where: F s4 F is the tipping force generated by the heavy object at the front end of the fork. S3 is the tipping force generated by the second boom, F S1 is the stabilizing force of the frame, F S2 is the stabilizing force of the first arm. Expand the above formula to get:

[0089]

[0090] From the above, it can be seen that the tipping moment and stabilizing moment of the forklift in static state are associated with the boom length, boom angle and rear axle margin (load) output by the force limit controller. Therefore, the input of the moment calculation model in step S30 includes parameters such as the boom weight, the weight of the vehicle body, the distance between the front and rear wheels, the length of the boom head connection device, the length of the fork, etc., which are known and relatively fixed values, as well as information such as the boom length (when the boom is retractable, the length of the first and second booms are variable), load (the weight of the cargo carried may change during the operation of the forklift), etc.

[0091] Based on the above analysis, the real-time tipping moment and stabilizing moment of the boom can be calculated, and the force limiter outputs the percentage of tipping moment and stabilizing moment in real time. In actual working conditions, when the operator steps on the accelerator and pushes the boom boom handle to perform the boom boom lowering action, the solenoid valve corresponding to the handle opening has a fixed opening (i.e., the target opening), and the accelerator pedal opening corresponds to a fixed speed. Therefore, based on the power generated by the hydraulic system on the cylinder, the acceleration applied by the hydraulic system to the boom boom cylinder during the process from static to moving can be calculated, and then the linear acceleration of the weight at the end of the boom and the stable boom boom linear speed at the end of the boom after the acceleration are calculated, thereby calculating the real-time change relationship between the tipping moment and the stabilizing moment from the static moment to the dynamic moment. Therefore, there are two stages when the boom is transformed from a static process to a dynamic process, namely the acceleration stage and the stable speed stage. The calculation formulas for the dynamic torque and stable torque of the entire system in the acceleration stage are as follows. In the acceleration stage, the power of the hydraulic system is all consumed in the acceleration kinetic energy of the boom from static to motion. According to the boom's acceleration from static to stable speed movement, the cylinder flow of the hydraulic system is Q and the effective area of ​​the rodless chamber is S 无 , acceleration a of the variable amplitude lowering cylinder movement, load force E m There is the following relationship. First, the cylinder flow rate Q is equal to the rate of change of the liquid volume in the cylinder, that is:

[0092] Q=S·V

[0093] Where: V is the movement speed of the cylinder piston;

[0094] The acceleration a can be obtained by differentiating the velocity V with respect to time, that is:

[0095]

[0096] therefore

[0097]

[0098] Among them, q 0 is the displacement of the variable-luffing main pump. Since the position of the oil cylinder (piston position) has a one-to-one corresponding oil cylinder angle, the acceleration of the oil cylinder movement can be equivalent to the acceleration of the oil cylinder angle. Since the oil cylinder angle corresponds to the boom angle, the acceleration of the oil cylinder is directly related to the angular acceleration of the boom. Therefore, the acceleration of the oil cylinder can be transformed into the acceleration of the boom. The flow entering the oil cylinder is related to the engine speed and the opening of the solenoid valve. Therefore, the above formula can be equivalent to:

[0099]

[0100] Where: H is the handle opening (per thousandth opening), n is the engine speed, J is the proportional coefficient of the cylinder flow and the cylinder speed, the value of J is affected by the engine speed, I max is the maximum current of the solenoid valve, I min It is the minimum current of the calibrated amplitude drop of the solenoid valve;

[0101]

[0102] Where: J1 is the structural coefficient corresponding to the cylinder stroke and cylinder angle (can be determined in advance), a θ1 is the angular acceleration of the boom, f(θ1) is the angle of θ2;

[0103] Therefore, the overturning acceleration force in the downward direction of the amplitude change generated during the process of amplitude change downward acceleration is:

[0104]

[0105] After analysis, it can be seen that the dynamic process mainly applies a force that causes the amplitude to change downward compared to the static process, and this force changes in real time with the angle and the boom movement speed, resulting in real-time changes in the tipping moment and the stabilizing moment. Since the static moment has been calculated above, the acceleration process and the stable speed amplitude drop process can be calculated. The numerical calculation relationship between the tipping moment and the stabilizing moment can be used to obtain the tipping moment of the acceleration process. The specific calculation is as follows:

[0106]

[0107] M 倾翻 =F S4 ·L 4 +F S3 ·L 3 +F 倾加 L 合

[0108]

[0109] M 稳定 =F S1 ·L 1 +F S2 ·L 2 +F 稳加 L 2

[0110]

[0111] In the embodiment of the present application, the boom luffing and descending start and acceleration operating condition type can be determined, for example, in the following manner:

[0112] The handle is operated to indicate that the boom begins to drop in variable amplitude (for example, the operator operates the handle so that the handle is pushed in a direction indicating that the boom drops in variable amplitude (for the handle opening)), which can be used to determine whether the boom enters a uniform descent state during the variable amplitude descent process. For example, the angle information (θ1) of the boom detected by the angle sensor is used to determine whether the boom enters a uniform descent state during the variable amplitude descent process. If the boom enters a uniform descent state, it indicates that the current working condition type has ended and the next working condition type (uniform descent working condition) is switched to.

[0113] Based on the above calculation, the tipping torque and stabilizing torque in the process of variable amplitude lowering startup can be obtained. At the same time, it can be seen that the tipping torque and stabilizing torque are related to the acceleration of the variable amplitude lowering action of the handle controlling the boom, and the acceleration of the variable amplitude lowering action is directly related to the acceleration of the cylinder action, and the movement acceleration of the cylinder is related to the opening of the solenoid valve controlled by the electronic control system and the time to reach the target opening. Therefore, the relationship between the tipping torque and the stabilizing torque in the process of variable amplitude lowering startup can be simplified to the target opening of the solenoid valve and the response time to reach the target opening. The tipping torque and the stabilizing torque are both functions of the time derivative of the valve opening. In the acceleration process of variable amplitude lowering, it is necessary to always ensure that the tipping torque is less than the stabilizing torque. Therefore, it is only necessary to control the valve opening and the acceleration time of the valve to ensure that the tipping torque is always less than the stabilizing torque. The control equation related to the tipping torque and the stabilizing torque can be simplified as:

[0114]

[0115] Where: f(△M) is the function associated with angle and lever arm, which is extracted by difference between stabilizing moment and overturning moment;

[0116] During the process of boom luffing startup, the acceleration force generated by the acceleration and the change of the boom angle will affect the tipping moment and the stabilizing moment. Since the acceleration time is short, the impact on the moment should be given priority to the impact of the acceleration force on the tipping moment and the stabilizing moment. Since the tipping moment of the boom angle will inevitably increase and the stabilizing moment will inevitably decrease due to the luffing downward, the angle needs to be added to the process of luffing acceleration, and the angle coefficient w is introduced. Therefore, the above formula can be further optimized as follows:

[0117]

[0118] Wherein: the value range of w can be determined in advance based on expert experience. The shorter the acceleration time, the larger the value of w, and the longer the acceleration time, the smaller the value of w. For example, the value of w can be measured in advance under different circumstances and stored in the expert database. In actual use, the value of w can be determined according to the opening degree of the handle when the handle is operated to perform the boom amplitude reduction operation (corresponding to the target speed). For the entire forklift's amplitude control system, when the handle is operated to an opening degree, it means that the set speed for the boom to stably change the amplitude and decrease has been determined. According to the size of the set speed, the size of the boom's acceleration and descent time from the prohibition can be determined. Therefore, after the handle opening information is known, the w value corresponding to the opening degree (or speed) can be found from the expert database. For example, the value of w can be 0.8 to 1.

[0119] Based on the derivation of the above mathematical model of the variable amplitude lowering tipping torque and stabilizing torque, it can be seen that the change in the dynamic torque of the variable amplitude during the acceleration process is based on the static torque before starting and the dynamic torque superimposed by the power provided by the hydraulic system to make the boom move. When the boom starts to move up and down based on the handle pushing to a certain opening, the target current of the solenoid valve of the variable amplitude lowering is a desired fixed value, but the dynamic torque changes with the time of acceleration to the target expected value. Finally, it can be known that the dynamic torque is a function related to the opening of the solenoid valve and time. Based on the above mathematical model, the two parameters of the solenoid valve opening and the acceleration ramp time can be controlled to adjust the stabilizing torque and tipping torque, so that the tipping torque is always close to the stabilizing torque, but always less than the stabilizing torque. Therefore, the optimal acceleration time and valve opening can be obtained as shown below:

[0120]

[0121] f(M 稳定 -M 倾翻 ) is the function of the difference between the stabilizing moment and the overturning moment per unit time. When f(M 稳定-M tilt infinitely approaches 0, indicating that the tilting torque is infinitely close to the stabilizing torque, which means that the control reaches the maximum acceleration movement within the safety limit. In this embodiment, the torque calculation model involved in step S30 can be constructed according to the above formula.

[0122] In the embodiment of the present application, the current moment and the next moment can be one or more control cycles, for example, 50ms, 100ms, etc. In the embodiment of the present application, the current of the solenoid valve can be controlled by PID (for example, the current is modulated by PWM). When the operator steps on the accelerator pedal and pushes the handle to make the boom start to move with variable amplitude and descend, for the controller, the accelerator pedal opening and the handle opening can be known by stepping on the accelerator pedal and pushing the handle. The accelerator pedal opening corresponds to the engine speed, and the handle opening corresponds to the target opening of the solenoid valve (the target opening corresponds to the target current of the solenoid valve). The acceleration (for example, linear acceleration or angular acceleration) of the boom during the process from static to moving can be calculated according to the handle opening and the engine speed as above. In fact, after obtaining the engine speed, the handle opening and the boom angle, the controller can input these parameters into the torque calculation model to calculate the current stabilizing torque and tipping torque, or the difference between the current stabilizing torque and tipping torque. In addition, the controller can also predict the stabilizing torque and overturning torque (or the difference between the stabilizing torque and the overturning torque) at the next moment (for example, the next one or more control cycles) based on the current boom angle and boom angular acceleration. Then compare the difference between the stabilizing torque and the overturning torque at the next moment (which can be called the second difference) with the difference between the current stabilizing torque and the overturning torque (which can be called the first difference). If the second difference is larger than the first difference, the valve control current of the solenoid valve can be increased. If the second difference is smaller than the first difference, the valve control current of the solenoid valve can be reduced. More specifically, in one example, the difference between the second difference and the first difference and the boom angle at the next moment are substituted into the above control equation f(M 稳定 -M 倾翻 ), solve the optimal solution of the handle opening H that makes the control equation greater than zero and close to zero (or close to a set value greater than zero), and obtain the corresponding current of the solenoid valve based on the optimal solution, which is the current adjustment amount △I of the valve control current at the next moment.

[0123] Figure 4 The diagram schematically shows the corresponding relationship between the movement speed of the hydraulic system's boom cylinder and the actual boom movement speed in the anti-rollover control method for a forklift according to an embodiment of the present application under the condition of constant-speed descent of the boom. Figure 4After the acceleration of the boom is completed, since there is a fixed corresponding relationship between the angle of the boom cylinder and the boom angle, during the movement of the boom to control the boom to do the boom lowering and lowering with the fork-loaded load, there is a fixed corresponding relationship between the movement speed of the hydraulic system boom cylinder and the actual movement speed of the boom. Therefore, the actual movement speed of the rodless cavity of the hydraulic system can be obtained, and the movement speed of each center of gravity of the actual boom can be obtained. The specific calculation is as follows:

[0124]

[0125] Where, PwmI 降 is the thousandth opening of the solenoid valve (arm variable amplitude lowering solenoid valve), I max is the maximum current of the solenoid valve, I min is the minimum current of the solenoid valve, H is the handle opening, q 0 is the displacement of the variable amplitude main pump, n is the engine speed, S 无 is the cross-sectional area of ​​the rodless cavity, r is the distance from the fulcrum of the cylinder and the boom to the end of the boom, f(θ1) is the mathematical conversion formula of the cylinder angle compared to the boom angle, L is the current boom length, V 2 is the linear velocity of the center of gravity of the first boom section, V 3 is the linear velocity of the center of gravity of the second boom, V 4 is the linear velocity of the load center of gravity.

[0126] There is a fixed corresponding relationship between the angle of the boom cylinder and the boom angle. Therefore, when the forklift controls the boom to make a variable amplitude drop at a certain speed, there is also a fixed corresponding relationship between the tipping moment and the stabilizing moment. Therefore, the tipping moment and the stabilizing moment can be obtained as follows:

[0127] M 倾翻 =F S4 ·L 4 +F S3 ·L 3 +F S4 ·V 4 ·L 4 +F S3 ·V 3 ·L s

[0128] After expansion:

[0129]

[0130]

[0131] M 稳定 =F S1 ·L 1 +F s2 ·L2 +F S2 ·V 2 ·L 2

[0132] After expansion:

[0133]

[0134] △M=M 稳定 -M 倾翻

[0135] The above formula is when the arm angle is θ1, the handle opening is H, and the arm angular velocity is ω θ1 The numerical relationship between the tipping moment and the stabilizing moment of the forklift truck, where the solenoid valve control current related to the handle opening The relationship between the difference between the tipping moment and the stabilizing moment and the handle opening can be obtained:

[0136]

[0137] f(M 稳定 -M 倾翻 ) is the angle θ1, a function of the difference between the single tipping moment and the stabilizing moment associated with the handle opening, and f(△M2) is a function associated with the boom angle and the lever arm for extracting the difference between the stabilizing moment and the tipping moment. Control the handle opening H so that f(M 稳定 -M 倾翻 ) infinitely approaches 0, indicating that the tipping moment is infinitely close to the stabilizing moment. At this time, it means that the control boom amplitude reduction reaches the maximum movement within the safety limit;

[0138] As the boom continues to change its amplitude, the angle of the amplitude continues to decrease. As the boom angle decreases, the tipping moment continues to increase, and the stabilizing moment continues to decrease. The relative angle of the boom in the next stage can be calculated in real time based on the handle opening and the angular velocity of the movement. Therefore, based on the current angle and the amplitude change speed combined with the movement speed time t, the angle θi of the boom amplitude change at the next moment can be calculated in real time.

[0139] θi=θ1+ω θ1 △t

[0140] Where: θ1 is the current boom angle, ω θ1 is the boom luffing angular velocity, △t is the boom luffing time;

[0141] Therefore, according to the torque relationship of the current angle and the angular velocity of the boom, the relationship between the stabilizing torque and the tipping torque at the next angle can be directly predicted;

[0142]

[0143] Where: f(M,t) is the optimal difference real-time matching function based on the current torque difference, the current boom angle, and the amplitude angular velocity based on time t, and f(θi) is a function related to angle and time. In this embodiment, the torque calculation model involved in step S30 can be constructed according to the above formula.

[0144] Since the speed of the boom luffing is determined based on the handle opening, the angle of the boom luffing changes with the angular velocity and time of the boom luffing. When the luffing angle and movement speed at the current moment are obtained, the tipping moment and stabilizing moment of the current boom luffing can be calculated. When the handle opening remains unchanged, the tipping moment and stabilizing moment of the next boom luffing angle after a certain period of time can be further predicted. Therefore, the controller can calculate the tipping moment and stabilizing moment of the next moment in real time based on the input of the current parameters, and then feed-forward adjust the valve-controlled current of the luffing, so as to realize real-time matching of the anti-tipping current as the luffing action occurs.

[0145] In this embodiment, when the detected boom angle changes at a constant speed, it can be determined that the boom has entered this operating condition type during the variable amplitude drop. Under this operating condition type, the controller can calculate the first difference between the current stabilizing torque and the current tipping torque and the second difference between the stabilizing torque and the tipping torque predicted at the next moment according to the above formula, and then adjust the valve control current of the solenoid valve according to the comparison result of the second difference and the first difference.

[0146] When the operator releases the variable amplitude lowering action (i.e., releases the handle, and the handle automatically returns to zero), the controller will close the valve control current of the electromagnetic valve variable amplitude lowering for a certain period of time. Since the downward movement of the boom stops suddenly, the whole will generate an acceleration downward along the tangent direction of the boom. If the valve closing time is too short and the acceleration is large enough, it is very likely to cause tipping. Therefore, the tipping torque and stabilizing torque of the boom variable amplitude lowering stop condition change based on the change of acceleration that stops the boom, and the push amplitude of the handle is converted into the user's expected movement speed ω i , the acceleration can be derived based on the current speed and time as follows:

[0147]

[0148] Where: a i is the angular acceleration, and since a i It is directly related to the valve control current, so it can be equivalent to:

[0149]

[0150] During the process of stopping the boom luffing, the dynamic torque is similar to the acceleration process of the boom luffing. The acceleration force in the acceleration process is provided by the driving force of the hydraulic system, while the deceleration torque of the boom luffing is provided by the momentum of the initial speed. Therefore, the specific mathematical relationship between the tipping torque and the stabilizing torque in the deceleration process is as follows:

[0151]

[0152] M 倾翻 =F S4 ·L 4 +F S3 ·L 3 +F 倾加 L 合

[0153]

[0154] M 稳定 =F S1 ·L 1 +F s2 ·L 2 +F 稳加 L 2

[0155]

[0156] The above formula is when the arm angle is θ1, the handle opening is H, and the arm angular velocity is ω θ1 The numerical relationship between the tipping moment and the stabilizing moment of the forklift during deceleration, where the valve control current related to the handle opening The relationship between the difference between the tipping moment and the stabilizing moment and the handle opening can be obtained:

[0157] f(M 稳定 -M 倾翻 )=f(△M3)·(a i );

[0158] f(M 稳定 -M 倾翻 ) is the arm angle θ1, a function of the difference between the single tipping moment and the stabilizing moment associated with the handle opening, and f(△M3) is a function associated with the angle and the lever arm for extracting the difference between the stabilizing moment and the tipping moment; a i is the acceleration generated by the valve control current of the solenoid valve from the current current closing to 0. Therefore, it can be seen that if the deceleration time is too fast, the acceleration will become very large, and the overturning torque generated by the acceleration of the boom stop will increase sharply. Therefore, by controlling the time when the current valve control current decreases to 0, the stop acceleration tends to a stable range, so that f(M稳定 -M 倾翻 ) infinitely approaches 0, indicating that the tipping moment is infinitely close to the stabilizing moment, which means that the control arm can stop the fastest time of variable amplitude drop. In this embodiment, the moment calculation model involved in step S30 can be constructed according to the above formula.

[0159] In this embodiment, the determination of the working condition type can be achieved, for example, by detecting the opening of the handle. For example, when it is detected that the handle returns to zero from an opening, it can be determined that it is in the variable amplitude descending deceleration stop working condition. Under this working condition type, the controller can obtain the current boom angle of the boom when entering this working condition type, and substitute the current boom angle into the above-mentioned function f(M 稳定 -M 倾翻 ), find the solution such that f(M 稳定 -M 倾翻 ) is an optimal solution for the boom angular acceleration that is greater than zero and approaches zero (or a set value greater than zero). According to the optimal solution, the corresponding handle opening value can be obtained (at this time, the difference between the stabilizing torque and the tipping torque is zero or the set value (first difference)), thereby obtaining the corresponding valve-controlled current of the solenoid valve. The boom angle at the next moment can be predicted based on the current boom angle and the boom angular acceleration. The predicted boom angle and the boom angular acceleration are substituted into the above formula to predict the difference (second difference) between the stabilizing torque and the tipping torque at the next moment. The controller then compares the second difference with the first difference. If the second difference is larger than the first difference, the valve-controlled current of the solenoid valve can be increased. If the second difference is smaller than the first difference, the valve-controlled current of the solenoid valve can be reduced. In one example, the method for determining the current adjustment amount of the valve-controlled current can be similar to the method for determining it in the boom variable amplitude descent start and acceleration operating condition type.

[0160] In an embodiment of the present application, a controller is provided, which is configured to execute the anti-rollover control method for a forklift according to any of the above embodiments.

[0161] In an embodiment of the present application, an anti-rollover control device for a forklift is provided. The forklift includes a boom, a handle, an engine, a hydraulic cylinder, and a solenoid valve. The solenoid valve is used to adjust the retraction speed of the hydraulic cylinder to adjust the variable amplitude lowering speed of the boom. The anti-rollover control device includes:

[0162] an angle sensor configured to detect an angle of the boom; and

[0163] A controller according to any of the above embodiments.

[0164] In an embodiment of the present application, a forklift is provided, comprising:

[0165] Boom;

[0166] handle;

[0167] engine;

[0168] Hydraulic cylinder;

[0169] A solenoid valve for adjusting the retraction speed of the hydraulic cylinder to adjust the luffing and lowering speed of the boom; and

[0170] An anti-rollover control device for a forklift according to any of the above embodiments.

[0171] In an embodiment of the present application, a machine-readable storage medium is provided, on which instructions are stored, and the instructions are used to enable a machine to execute the anti-rollover control method for a forklift truck of any of the above embodiments.

[0172] In the above scheme provided in the embodiment of the present application, the controller can establish a mathematical model of the rollover moment and the stabilizing moment under various working conditions based on the parameters obtained by the sensor and the existing parameters of the boom system, and analyze the change trends of the rollover moment and the stabilizing moment in the boom movement process and the anti-rollover control method under the three anti-rollover working modes. It can be seen from the mathematical model that in the process of starting the boom amplitude reduction, it is mainly the acceleration of the cylinder movement caused by the starting force of the hydraulic system that generates an acceleration force on the entire system, causing a sudden change in the rollover moment and the stabilizing moment. In the process of constant speed amplitude reduction of the boom, based on the momentum theorem analysis, the dynamic torque generated by the kinetic force generated by the moving object changes with the angle and the rollover moment increases as the angle becomes smaller. In the process of stopping the boom amplitude reduction, it is mainly the sudden stopping force of the hydraulic system on the entire system that suppresses the acceleration generated by the downward movement of the boom to generate the downward acceleration force on the entire system. Since the movement speed can be calculated in real time during the variable amplitude lowering movement, the angle changes regularly with time. The working angle of the boom at the next moment can be calculated based on the existing boom angle, and then the tipping torque and stabilizing torque at the next moment when the target movement speed is reached can be calculated. Through the above calculations, the controller can predict the tipping torque and stabilizing torque at the next moment in advance. Therefore, the difference between the tipping torque and the stabilizing torque can be feedforward matched by controlling the current of the solenoid valve, so that the difference between the tipping torque and the stabilizing torque is always kept within a safe range, thereby achieving the effect of real-time prediction of anti-rollover. Compared with simply using a force limiter to prevent rollover, the dynamic load real-time prediction technology has the advantages of fast response, high matching degree and no hysteresis.

[0173] Those skilled in the art will appreciate that the embodiments of the present application may be provided as methods, systems, or computer program products. Therefore, the present application may adopt the form of a complete hardware embodiment, a complete software embodiment, or an embodiment in combination with software and hardware. Moreover, the present application may adopt the form of a computer program product implemented in one or more computer-usable storage media (including but not limited to disk storage, CD-ROM, optical storage, etc.) that include computer-usable program code.

[0174] The present application is described with reference to the flowcharts and / or block diagrams of the methods, devices (systems), and computer program products according to the embodiments of the present application. It should be understood that each process and / or box in the flowchart and / or block diagram, as well as the combination of the processes and / or boxes in the flowchart and / or block diagram, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, a special-purpose computer, an embedded processor, or other programmable data processing device to generate a machine, so that the instructions executed by the processor of the computer or other programmable data processing device generate instructions for implementing the processes in the flowchart and / or block diagram. Figure 1 A process or multiple processes and / or boxes Figure 1 A device that provides the functions specified in a block or multiple blocks.

[0175] These computer program instructions may also be stored in a computer-readable memory capable of directing a computer or other programmable data processing device to operate in a specific manner, so that the instructions stored in the computer-readable memory produce an article of manufacture comprising an instruction device, which implements the process Figure 1 A process or multiple processes and / or boxes Figure 1 A function specified in one or more boxes.

[0176] These computer program instructions can also be loaded onto a computer or other programmable data processing device so that a series of operating steps are executed on the computer or other programmable device to produce a computer-implemented process, thereby providing instructions for implementing the process in the computer or other programmable device. Figure 1 A process or multiple processes and / or boxes Figure 1 The steps for the functions specified in one or more boxes.

[0177] In a typical configuration, a computing device includes one or more processors (CPU), input / output interfaces, network interfaces, and memory.

[0178] The memory may include non-permanent memory in a computer-readable medium, random access memory (RAM) and / or non-volatile memory in the form of read-only memory (ROM) or flash RAM. The memory is an example of a computer-readable medium.

[0179] Computer readable media include permanent and non-permanent, removable and non-removable media that can be implemented by any method or technology to store information. 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 technology, compact disk read-only memory (CD-ROM), digital versatile disk (DVD) or other optical storage, magnetic cassettes, magnetic tape magnetic disk storage or other magnetic storage devices or any other non-transmission media that can be used to store information that can be accessed by a computing device. As defined herein, computer readable media does not include temporary computer readable media (transitory media), such as modulated data signals and carrier waves.

[0180] It should also be noted that the terms "include", "comprises" or any other variations thereof are intended to cover non-exclusive inclusion, so that a process, method, commodity or device including a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, commodity or device. In the absence of more restrictions, the elements defined by the sentence "comprises a ..." do not exclude the existence of other identical elements in the process, method, commodity or device including the elements.

[0181] The above are only embodiments of the present application and are not intended to limit the present application. For those skilled in the art, the present application may have various changes and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application should be included within the scope of the claims of the present application.

Claims

1. A method for controlling the rollover prevention of a forklift, characterized in that: The forklift comprises an arm, a handle, an engine, a hydraulic cylinder and a solenoid valve, wherein the solenoid valve is used to adjust the retraction speed of the hydraulic cylinder to adjust the variable amplitude descending speed of the arm, and the anti-rollover control method comprises: Acquiring handle opening information of the handle, speed information of the engine, and arm angle information of the arm; Determining the type of working condition the boom is in when luffing and lowering; Inputting the handle opening information, the rotation speed information and the boom angle information into a torque calculation model corresponding to the determined working condition type to determine a first difference between a current stabilizing torque and a current tipping torque; Using the torque calculation model to predict a second difference between the stabilizing torque and the overturning torque at the next moment; The valve control current of the solenoid valve is controlled according to a change of the second difference relative to the first difference.

2. The anti-rollover control method according to claim 1, characterized in that: The controlling the valve control current of the solenoid valve according to the change of the second difference relative to the first difference comprises: When the second difference becomes larger than the first difference, increasing the valve-controlled current; and When the second difference becomes smaller than the first difference, the valve control current is reduced.

3. The anti-rollover control method according to claim 2, characterized in that: The operating condition type is one of the following: The conditions include starting and accelerating the variable amplitude descent, descending at a constant speed with variable amplitude descent, and decelerating and stopping the variable amplitude descent.

4. The anti-rollover control method according to claim 3, characterized in that: When the determined operating condition type is the variable amplitude descent start and acceleration operating condition: The using the moment calculation model to predict a second difference between the stabilizing moment and the overturning moment at the next moment comprises: Determining the angular acceleration of the arm according to the handle opening information and the rotation speed information; Predicting a boom angle at a next moment according to the current boom angle of the boom and the angular acceleration; A second difference between the tipping moment and the stabilizing moment at a next moment is predicted according to the predicted boom angle and the angular acceleration.

5. The anti-rollover control method according to claim 4, characterized in that: The controlling the valve-controlled current of the solenoid valve according to the change of the second difference relative to the first difference further comprises: Calculating an optimal handle opening value according to the difference between the second difference and the first difference and the predicted arm angle at the next moment; The adjustment amount of the valve control current of the solenoid valve at the next moment is determined according to the optimal handle opening value.

6. The anti-rollover control method according to claim 3, characterized in that: When the determined operating condition type is the variable amplitude descent constant speed descent operating condition: The using the moment calculation model to predict a second difference between the stabilizing moment and the overturning moment at the next moment comprises: Determining the angular velocity of the boom according to the handle opening information, the rotation speed information and the current boom angle of the boom; Predicting the boom angle at the next moment according to the current boom angle and the angular velocity; A second difference between the stabilizing moment and the overturning moment at the next moment is predicted according to the predicted boom angle.

7. The anti-rollover control method according to claim 3, characterized in that: When the determined operating condition type is the variable amplitude descending deceleration stop operating condition: The using the moment calculation model to predict a second difference between the stabilizing moment and the overturning moment at the next moment comprises: Determining the angular acceleration of the arm according to the handle opening information; Predicting a boom angle at a next moment according to the current boom angle of the boom and the angular acceleration; A second difference between the stabilizing moment and the tipping moment at a next moment is predicted according to the predicted boom angle and the angular acceleration.

8. The anti-rollover control method according to claim 3, characterized in that: The controlling the valve-controlled current of the solenoid valve according to the change of the second difference relative to the first difference further comprises: Acquire the current boom angle when entering the luffing, descending, decelerating and stopping working condition; Inputting the current boom angle into the torque calculation model to obtain the optimal angular acceleration of the boom; Determining a corresponding handle opening value according to the optimal angular acceleration; The current valve-controlled current value of the solenoid valve is determined according to the corresponding handle opening value.

9. The anti-rollover control method according to claim 3, characterized in that: The torque calculation model corresponding to the variable amplitude descent start and acceleration working condition is associated with the boom angle, handle opening and engine speed; The torque calculation model corresponding to the variable amplitude descent constant speed descent working condition is associated with the boom angle and the handle opening; The torque calculation model corresponding to the variable amplitude descending deceleration stop working condition is associated with the boom angle and the handle opening.

10. A controller, characterized in that: The method is configured to execute the anti-rollover control method for a forklift according to any one of claims 1 to 9.

11. An anti-rollover control device for a forklift, characterized in that: The forklift truck includes a boom, a handle, an engine, a hydraulic cylinder and a solenoid valve, wherein the solenoid valve is used to adjust the retraction speed of the hydraulic cylinder to adjust the variable amplitude descending speed of the boom, and the anti-rollover control device includes: an angle sensor configured to detect an angle of the boom; and A controller according to claim 10.

12. A forklift, characterized in that: include: Boom; handle; engine; Hydraulic cylinder; A solenoid valve, used to adjust the retraction speed of the hydraulic cylinder to adjust the luffing and lowering speed of the boom; and The anti-rollover control device for a forklift according to claim 11.

13. A machine-readable storage medium having instructions stored thereon, the instructions being used to enable a machine to execute the anti-rollover control method for a forklift according to any one of claims 1 to 9.

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