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

Abstract

The application provides a forklift and a rollover prevention control method, a controller and a control device thereof. The forklift comprises an arm support, 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 luffing speed of the arm support. The method comprises: obtaining handle opening degree information of the handle, engine speed information and arm support angle information of the arm support; determining the working condition type of the arm support during luffing; inputting the handle opening degree information, the engine speed information and the arm support angle information into a torque calculation model corresponding to the determined working condition type to determine a first difference value between a current stable torque and a current rollover torque; using the torque calculation model to predict a second difference value between a stable torque and a rollover torque at a next time; and controlling the valve control current of the solenoid valve according to the change of the second difference value relative to the first difference value. The present scheme uses a feedforward prediction method to respond faster and has no hysteresis, and can achieve real-time rollover prevention matching.

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 boom and off-road capabilities. Combining the functions of both a forklift and a crane, it offers a wide range of capabilities. By replacing various attachments, it can perform various functions, such as high-altitude forklift loading, hoisting, passenger transport, and shoveling. Its complex operating conditions place higher demands on the safety and stability of the entire vehicle. This is especially true during boom lowering and boom extension operations. As the main boom angle decreases and the boom extends, the tipping moment at the front of the vehicle and the vehicle's stabilizing moment constantly change, leading to dynamic changes in the vehicle's anti-rollover stability. Maintaining operational efficiency while balancing safety is a technical challenge 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. Its 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 based on 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 actual operation, forklifts need to quickly move cargo, lifting or lowering cargo, or other complex movements. Due to the high randomness of the load, the speed of the corresponding movements varies greatly with changes in boom length and angle, as well as the difference in handle operation opening and engine speed. Therefore, when the target operating speed is achieved by combining multiple factors such as handle opening, engine speed, and load, the vehicle's anti-rollover torque changes in real time. Especially under large-angle, fully extended, and heavy-load conditions, the moment the boom is adjusted, the cylinder gives a starting speed, and the rollover torque increases sharply, far exceeding the calibrated rollover torque. Therefore, rollover occurs before the force limiter has time to cut off. Or under large-angle, fully extended, and heavy-load conditions, the moment the boom is adjusted to a stop, the rollover torque generated by the gravitational potential energy boom and the downward acceleration of the cargo, combined with the long lever arm, will also increase dramatically, causing the vehicle to roll over. The current common force limiter solution detects the rear axle force limit margin. Since this detection is performed during the process, there is a certain lag. The most critical issue is that when the load is large and heavy, part of the heavy load's force is pressed against the rear axle, resulting in the force limiter detecting that the rear axle margin is safe at this time. The force limit value at this time may be the same as the force limit value under a light load condition. However, under heavy load conditions, part of the force is also distributed to the front tipping side. At the moment of startup, this force component multiplied by the large lever arm generates a tipping torque that is far greater than the torque of the same force limit value under light load. Therefore, the force limiter system cannot distinguish between heavy and light loads. If the same speed is used to control the boom movement under the same force limit, 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 for variable amplitude reduction changes in real time with the driver's operating intention, and the tipping torque changes accordingly. 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] To achieve the above-mentioned objectives, the present application provides, in a first aspect, an anti-rollover control method for a forklift truck. The forklift truck 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 boom's luffing and lowering speed. The anti-rollover control method includes:

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

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

[0008] Inputting the handle opening information, the 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] predicting a second difference between the stabilizing moment and the overturning moment at the next moment using a moment calculation model;

[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 an embodiment of the present application, controlling the valve-controlled current of the solenoid valve according to a change in 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 variable amplitude descent starts and accelerates, the variable amplitude descents at a constant speed, and the variable amplitude descents decelerates and stops.

[0016] In the embodiment of the present application, when the determined operating condition type is a variable-range descending 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 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 overturning moment and the stabilizing moment at a next moment is predicted based on the predicted boom angle and angular acceleration.

[0021] In the embodiment of the present application, controlling the valve-controlled current of the solenoid valve according to a change in 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 a 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 the variable amplitude descending deceleration stop operating 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 overturning moment at a next moment is predicted based on the predicted boom angle and angular acceleration.

[0034] In the embodiment of the present application, controlling the valve-controlled current of the solenoid valve according to a change in 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-controlled 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 luffing, descending, deceleration and stopping 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] In a third aspect, 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 boom-lowering speed, the anti-rollover control device comprising:

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

[0045] The controller mentioned above.

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

[0047] boom;

[0048] handle;

[0049] engine;

[0050] Hydraulic cylinder;

[0051] A solenoid valve, used to adjust the retraction speed of the hydraulic cylinder to adjust the boom's luffing and lowering speed; 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 stored thereon instructions for causing a machine to execute the above-mentioned anti-rollover control method for a forklift.

[0054] The solution provided in the embodiments 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 rollover.

[0056] 2. Compared with the current traditional anti-rollover system, which mostly uses force limiters for force limit control, which has the disadvantages of not knowing the actual torque and having obvious hysteresis for dynamic torque, the technical solution of this application uses a feedforward prediction method with faster response, no hysteresis, and can achieve real-time anti-rollover matching;

[0057] 3. It can be applied to non-rotating functions, and there is no need to install a pressure sensor in the cylinder. Detection and control are performed through pure algorithms 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 detailed description. 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 detailed description, 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 according to 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 illustrates 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 diagram schematically illustrates the corresponding relationship between the movement speed of the hydraulic system's luffing cylinder and the actual movement speed of the boom luffing in the luffing descent constant speed descent condition in the anti-rollover control method for a forklift according to an embodiment of the present application. DETAILED DESCRIPTION

[0064] The following describes the specific implementation of the embodiment of the present application in detail with reference to the accompanying drawings. It should be understood that the specific implementation described herein is only used to illustrate and explain the embodiment of the present application and is not intended 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 limiter controller. The force sensor is installed on the rear axle of the forklift. The force limiter controller 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 under a heavy load, it will produce a large deformation. At this time, the entire vehicle is considered safe. When the load on the rear axle becomes smaller and a smaller deformation is produced, the entire vehicle is considered dangerous. According to the deformation caused by 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 rollover state calibrated when the entire machine is offline, the force limiter system can output the rear axle safety margin percentage in real time based on the rear axle deformation. When the forward rollover 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 the proportional relationship between the current tipping torque and the safety torque in a static state. However, this will cause two problems. First, the force limiter safety margin generated by a heavy load, large angle, and long arm extension is consistent with the force limiter safety margin generated by a certain light load working condition. This is because in a heavy load, large angle working condition, part of the heavy load's gravity component 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 the pressure 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 limiter safety margin in this working condition is likely to be consistent with a certain light load working condition. However, the tipping torque generated by a heavy load is much greater than that generated by a light load, and the heavy load working condition with the amplitude downward is more dangerous. The second issue is the sudden change in the tipping moment when the static system is converted to a dynamic system. During static operation, the tilting moment generated by heavy and light loads is proportional to the stabilizing moment due to the force component of the heavy load on the rear axle, and the rear axle safety margin provided by the force limiter is also the same. However, the tipping moment generated by heavy loads is much greater than that generated by light loads. As the boom begins to luff downward, the tipping moment changes. This change comes from three sources: the changing tipping force, the tipping lever arm, which constantly shifts in a dangerous direction, and the acceleration generated by the momentary acceleration of the luffing force generated by the cylinders combined with gravity. Stabilizing torque, on the other hand, only has two sources: the change in the stabilizing lever arm and the change in the stabilizing force. Therefore, when converting from a static system to a dynamic system, if the initial velocity applied by the operating handle is high, the acceleration generated by the momentary acceleration of the cylinders combined with gravity will increase instantaneously. This instantaneous increase in force, multiplied by the long lever arm, will generate a tipping moment that cannot be offset by the stabilizing moment. Because the stabilizing torque is aimed at the frame, which is a static object and has no acceleration force involved in the balance, 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 real-time torque and torque change trends, and therefore is only suitable for static and micro-motion systems. However, the non-rotating forklift loading process involves multiple loads, and the speed varies in real time based on driving requirements. The force limiter system is difficult to meet the requirements 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. Its 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, to 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 real-time torque and the trend of torque change, which leads to the problem of 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 shown schematically. Figure 1As shown, a forklift truck may include a vehicle body, a boom, a hydraulic system, a controller, a handle, and an accelerator pedal. One end (the tail) of the boom is mounted on the rear axle of the vehicle body. The hydraulic system may include an engine, a hydraulic pump, and a hydraulic cylinder. The engine is used to drive the hydraulic pump, which pumps 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 variable-speed movements (e.g., increasing or decreasing the boom). The hydraulic system may also include a hydraulic valve assembly, which may include, for example, a boom-lowering solenoid valve (e.g., a solenoid proportional valve) to regulate the flow of hydraulic oil in the hydraulic cylinder to adjust the speed of boom-lowering. The handle is used to set the boom's variable-speed direction and variable-speed. For example, the operator determines the boom's variable-speed direction by moving the handle in different directions (e.g., forward, backward, or reverse), and sets the target boom's variable-speed speed (a given speed) by adjusting the handle's travel (or handle opening). The accelerator pedal is used to set the engine's speed. Specifically, the travel of the accelerator pedal (or accelerator pedal opening) determines the engine's speed (a 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 the example where 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 boom extension, and a boom retraction solenoid valve for adjusting the speed of 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 the 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 relevant 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 entire 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 and 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, 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 based on the numerical relationship between the angle, handle opening, and accelerator pedal opening. Based on the above calculation, the difference between the current tipping torque and stabilizing torque of each anti-tip working mode and the difference between the tipping torque and stabilizing torque at the next moment 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-tip 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 its efficiency, the safety of the entire vehicle is improved, and the problem of the traditional force limiter system being unable to 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 entire 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 an arm, 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 luffing and 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 engine speed information and the boom angle information of the boom are obtained;

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

[0075] In step S30, the handle opening information, the 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 the current stabilizing torque and the current overturning 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: boom variable amplitude lowering start-up acceleration condition, boom variable amplitude lowering constant speed lowering condition, and boom variable amplitude lowering deceleration and stop condition. Each working mode can have a matching anti-rollover matching algorithm. 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 lever arm center of gravity S1, first-section arm lever arm center of gravity S2, second-section arm lever arm center of gravity S3, load center of gravity S4, stabilizing lever arm L1, first-section arm lever arm L2, second-section arm lever arm L3, and load combined lever arm L4. According to the vehicle efficiency calculation, the maximum arm amplitude change speed V1 that can be achieved by the arm amplitude change and the maximum extension and retraction speed V2 that can be achieved by the arm extension and retraction can be obtained when the arm is in position Si; 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. Based on the required working speed, its instantaneous acceleration is obtained 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. By controlling the current control of the amplitude change and retraction valves, the vehicle can reach the maximum safe movement speed V1safemax, V2safemax, realizing the real-time anti-rollover function of the vehicle while ensuring work efficiency.

[0079] In the embodiment of the present application, the vehicle's tilting and stabilizing forces can be calculated using the boom angle and cylinder angle, and thus the tilting and stabilizing torques can be calculated. During the boom's luffing and lowering motion, the angle of the luffing cylinder changes as the boom's luffing angle changes. Therefore, each boom angle θ1 corresponds to a corresponding cylinder angle θ2. Actual testing reveals the matching relationship between the boom's full-operation angle and the cylinder's full-operation angle. 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 rod and the boom, of course the angle between the cylinder rod and other reference (e.g. horizontal plane) is also feasible.

[0082] The actual load of the object on the forks of the forklift truck can be measured using force sensors arranged at the forks, 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 the load can be calculated based on the rear axle margin percentage and the moment balance. After obtaining the load, the controller can calculate the tilting moment of each section of the arm forward and the stabilizing moment, as well as the tilting moment of the heavy object at the front end of the forks, and then the actual load relationship at the front end of the forks can be converted. Figure 3 The forklift truck is shown as an example, wherein the boom includes two sections of arms, based on the corresponding relationship between the boom angle and the cylinder angle mapping and the rear axle margin percentage output by the force limiter, the boom amplitude lowering tilting moment M 倾翻 and the corresponding relationship of the stabilizing moment M 稳定 , the calculation formula is as follows:

[0083]

[0084] In the formula: K1m is the load weight, K2m is the first section of arm weight, K3m is the second section of boom self weight, K 车 m is the vehicle body self weight, L 轮 is the distance between front and rear wheels, L k2 is the first section of boom self length, L k3 is the second section of boom self length, L 连 is the length of the boom head connecting device, L 货 is the length of the forks, L1 is the stabilizing arm length, L2 is the first section of arm arm length, L3 is the second section of arm arm length, L4 is the load arm length.

[0085] Based on the above formula, the tilting moment M 倾翻 and the stabilizing moment M 稳定 when static can be obtained:

[0086] M 倾翻 = F S4 · L4 + F S3 · L3

[0087] M 稳定 = F S1 · L1 + F S2 · L2

[0088] In the formula: Fs4 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. Expanding the above formula, we have:

[0089]

[0090] As can be seen above, the tipping moment and stabilizing moment of a forklift in a static state are related to the boom length, boom angle, and the rear axle margin (load) output by the force limit controller. Therefore, the inputs to the torque calculation model in step S30 include not only known and relatively fixed parameters such as boom weight, vehicle weight, front and rear wheel distance, boom head connection length, and fork length, but also parameters such as boom length (if the boom is retractable, the lengths of the first and second boom sections are variable) and load (the weight of the cargo carried may vary during the operation of the forklift).

[0091] Based on the above analysis, the real-time tipping torque and stabilizing torque of the boom can be calculated, and the force limiter outputs the percentage of the tipping torque and stabilizing torque 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 of the boom from static to moving can be calculated, and then the linear acceleration of the weight at the end of the boom can be calculated, as well as the stable boom boom linear speed at the end of the boom after the acceleration is completed, thereby calculating the real-time change relationship between the tipping torque and the stabilizing torque 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 when the boom is variable and descending. According to the movement of the boom from static acceleration to stable speed, the cylinder flow of the hydraulic system is Q and the effective area of ​​the rodless cavity is S 无 , acceleration a of the variable amplitude lowering cylinder movement, load force E m The following relationship exists. 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] Where q0 is the displacement of the variable-luff main pump. Since the position of the cylinder (piston position) has a one-to-one correspondence with the cylinder angle, the acceleration of the cylinder movement can be equivalent to the acceleration of the cylinder angle. Since the cylinder angle corresponds to the boom angle, the cylinder acceleration is directly related to the angular acceleration of the boom. Therefore, the cylinder acceleration can be transformed into the boom acceleration. The flow rate entering the 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 The maximum current of the solenoid valve is calibrated, I min The minimum current of the solenoid valve’s calibrated amplitude drop;

[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 amplitude-downward direction generated during the amplitude-downward acceleration is:

[0104]

[0105] After analysis, it can be seen that the dynamic process mainly applies a force that causes the boom to change downward compared to the static process, and this force changes in real time with the angle and boom movement speed, causing the tipping moment and stabilizing moment to change in real time. Since the static moment has been calculated above, the acceleration process and the stable speed boom 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 L4+F S3 L3+F 倾加 L 合

[0108]

[0109] M 稳定 =F S1 L1+F S2 L2+F 稳加 L2

[0110]

[0111] In the embodiment of the present application, the boom luffing and lowering 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 has begun luffing and lowering (for example, the operator operates the handle so that the handle is pushed a certain distance (relative to the handle opening) in the direction indicating the boom luffing and lowering). This can be used to determine whether the boom has entered a uniform descent state during the luffing and lowering process. For example, the boom angle information (θ1) detected by the angle sensor is used to determine whether the boom has entered a uniform descent state during the luffing and lowering process. If the boom has entered a uniform descent state, this indicates that the current operating condition has ended and the next operating condition (uniform descent condition) has been switched to.

[0113] Based on the above calculations, the tipping torque and stabilizing torque during the variable amplitude lowering startup process can be obtained. At the same time, it can be seen that the tipping torque and stabilizing torque are both 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 motion 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 during the variable amplitude lowering startup process can be simplified to the direct relationship between 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. During the acceleration process of the 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 to:

[0114]

[0115] Where: f(△M) is the function related to angle and lever arm, which is obtained by extracting the difference between the stabilizing moment and the overturning moment;

[0116] During the boom luffing start-up process, the acceleration force generated by the acceleration and the change in boom angle will affect the tipping moment and the stabilizing moment. Since the acceleration time is short, the impact on the torque should be given priority to the impact of the acceleration force on the tipping moment and the stabilizing moment. Since the boom angle will inevitably increase and the stabilizing moment will inevitably decrease as the luffing moves downward, the angle needs to be added to the luffing acceleration process 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 boom is operated to perform the boom amplitude lowering operation (corresponding to the target speed). For the boom amplitude control system of the entire forklift, when the handle is operated to a certain opening degree, it means that the set speed for the boom to stably change the amplitude and lower has been determined. According to the size of the set speed, the size of the boom 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-mentioned mathematical model of the tilting torque and stabilizing torque of the variable amplitude, 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 variable amplitude lowering based on the handle pushing the amplitude 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 the tilting torque, so that the tilting 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 -Mtip infinitely approaches 0, indicating that the tipping torque is infinitely close to the stabilizing torque, which means that the control reaches the maximum acceleration 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 an 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 an embodiment of the present application, PID control can be adopted for the current of the solenoid valve (for example, the current is modulated by PWM). When the operator steps on the accelerator pedal and pushes the handle so that the boom starts to perform variable amplitude descending motion, the controller can obtain the accelerator pedal opening and the handle opening 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). As described above, the acceleration (for example, linear acceleration or angular acceleration) of the boom during the process of the boom from stationary to moving can be calculated based on the handle opening and the engine speed. 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 the 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 ), find 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 solenoid valve current based on the optimal solution. This current is the current adjustment amount △I of the valve control current at the next moment.

[0123] Figure 4 The diagram schematically illustrates the corresponding relationship between the movement speed of the hydraulic system's luffing cylinder and the actual movement speed of the boom luffing 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 luffing descent. Figure 4 After the luffing acceleration is completed, since there is a fixed correspondence between the angle of the luffing cylinder and the boom luffing angle, during the movement of the forklift to control the boom to perform luffing and lowering, there is a fixed correspondence between the movement speed of the hydraulic system luffing cylinder and the actual movement speed of the boom luffing. Therefore, the actual movement speed of the hydraulic system rodless cavity 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 ratio opening of the solenoid valve (arm boom lowering solenoid valve), I max The maximum current of the solenoid valve is calibrated, I min is the minimum current of the solenoid valve, H is the handle opening, q0 is the displacement of the 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, V2 is the linear velocity of the center of gravity of the first section of the boom, V3 is the linear velocity of the center of gravity of the second section of the boom, and V4 is the linear velocity of the center of gravity of the load.

[0126] The angle of the luffing cylinder and the boom luffing angle have a fixed corresponding relationship. Therefore, when the forklift controls the boom to perform luffing and lowering at a certain speed, the tipping moment and the stabilizing moment also have a fixed corresponding relationship. Therefore, the tipping moment and the stabilizing moment can be obtained as follows:

[0127] M 倾翻 =F S4 L4+F S3 L3+F S4 ·V4·L4+F S3 ·V3·L s

[0128] After expansion:

[0129]

[0130]

[0131] M 稳定 =F S1 L1+F s2 L2+F S2 V2 L2

[0132] After expansion:

[0133]

[0134] △M=M 稳定 -M 倾翻

[0135] The above formula is when the boom angle is θ1, the handle opening is H, and the boom angular velocity is ω θ1 The numerical relationship between the tipping torque and the stabilizing torque of the forklift, in which the solenoid valve control current related to the handle opening is The relationship between the difference between the tilting moment and the stabilizing moment at this time and the handle opening can be obtained:

[0136]

[0137] f(M 稳定 -M 倾翻 ) is a function of the single tilting moment and the stabilizing moment difference associated with the handle opening, and f(△M2) is a function of the stabilizing moment and the tilting moment difference associated with the boom angle and the force arm. The handle opening H is controlled so that f(M 稳定 -M 倾翻 ) approaches 0 infinitely, indicating that the tilting moment approaches the stabilizing moment infinitely, at which time it indicates that the control boom luffing reaches the maximum movement within the safety limit range;

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

[0139] θi = θ1 + ω θ1 △t

[0140] In the formula: θ1 is the current luffing angle of the boom, ω θ1 is the luffing angular velocity of the boom, and △t is the luffing time of the boom.

[0141] Therefore, according to the moment relationship of the current angle and the luffing angular velocity of the boom, the relationship between the stabilizing moment and the tilting moment at the next angle can be directly predicted.

[0142]

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

[0144] Since the speed of the boom arm amplitude reduction is determined based on the handle opening, the boom arm amplitude reduction angle changes with the angular velocity and time of the boom arm amplitude reduction. When the amplitude reduction angle and movement speed at the current moment are obtained, the current boom arm amplitude reduction tipping torque and stabilizing torque can be calculated. When the handle opening remains unchanged, the tipping torque and stabilizing torque of the next boom arm amplitude reduction angle after a certain period of time can be further predicted. Therefore, the controller can calculate the tipping torque and stabilizing torque at 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 amplitude reduction, so as to achieve real-time matching of the anti-tipping current as the amplitude reduction 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 during luffing and lowering. In this operating condition, the controller can calculate a first difference between the current stabilizing torque and the current tipping torque, and a second difference between the stabilizing torque and the tipping torque predicted at the next moment, according to the above formula. The controller then adjusts the solenoid valve's valve control current based on the comparison of the second difference with the first difference.

[0146] When the operator releases the boom lowering action (i.e., releases the handle, and the handle automatically returns to zero), the controller will shut off the valve control current of the solenoid valve for a certain period of time. Since the downward movement of the boom stops suddenly, an acceleration will be generated along the tangential 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 lowering stop condition change based on the acceleration that stops the boom. The push amplitude of the handle is converted into the user's expected movement speed ω in thousandths. i , the acceleration can be derived based on the current velocity 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 boom luffing and stopping process, the dynamic torque is similar to that during the acceleration process of the boom luffing and lowering. The acceleration force during the acceleration process is provided by the driving force of the hydraulic system, while the deceleration torque of the boom luffing and lowering is provided by the momentum of the initial velocity. Therefore, the specific mathematical relationship between the tipping torque and the stabilizing torque during the deceleration process is as follows:

[0151]

[0152] M 倾翻 =FS4 • L4 + F S3 • L3 + F 倾加 L 合

[0153]

[0154] M 稳定 = F S1 • L1 + F s2 • L2 + F 稳加 L2

[0155]

[0156] The above formula is the numerical relationship between the tilting moment and the stabilizing moment of the forklift truck during deceleration when the boom angle is θ1, the handle opening is H, and the boom angle velocity is ω θ1 The relationship between the difference between the tilting moment and the stabilizing moment at this time and the handle opening can be obtained as follows:

[0157] f(M 稳定 - M 倾翻 ) = f(△M3) • (a i );

[0158] f(M 稳定 - M 倾翻 ) is a function of the boom angle θ1 and the difference between the single tilting moment and the stabilizing moment associated with the handle opening, f(△M3) is a function associated with the angle and the force arm extracted by subtracting the stabilizing moment from the tilting moment; a i is the acceleration generated by the current valve control current of the electromagnetic valve being closed to 0. Therefore, it can be seen that if the deceleration time is too fast, the acceleration will become very large, and the tilting moment generated by the acceleration of the boom stop will increase sharply, so by controlling the time for the current valve control current to decrease to 0, the stop acceleration tends to a stable range, so that f(M 稳定 - M 倾翻 ) approaches 0 infinitely, indicating that the tilting moment approaches the stabilizing moment infinitely, at which time it indicates the fastest time to control the boom to stop descending. 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 position from an opening, it can be determined that it is in the boom descending deceleration stop working condition. In 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 function f(M 稳定 - M​倾翻 ), find the solution so that f(M 稳定 -M 倾翻 ) is greater than zero and approaches zero (or a set value greater than zero), and the optimal solution of the boom angular acceleration can be obtained 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)), and the valve-controlled current of the corresponding solenoid valve can be obtained. The boom angle at the next moment can be predicted based on the current boom angle and boom angular acceleration, and the predicted boom angle and boom angular acceleration are substituted into the above formula to predict the difference between the stabilizing torque and the tipping torque at the next moment (second difference). 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 current adjustment amount of the valve-controlled current can be determined in a similar manner to that in the boom amplitude drop 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 boom's luffing and lowering speed. The anti-rollover control device includes:

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

[0163] The controller of 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, used to adjust the retraction speed of the hydraulic cylinder to adjust the boom's luffing and lowering speed; and

[0170] The 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 according to any of the above embodiments.

[0172] The above-mentioned scheme provided in the embodiment of the present application, the controller can establish a mathematical model of the overturning torque and the stabilizing torque under various working conditions based on the parameters obtained by the sensor and the existing parameters of the boom system, and analyze the changing trends of the overturning torque and the stabilizing torque during the boom movement and the anti-overturning control method under the three anti-overturning working modes. It can be seen from the mathematical model that in the process of starting the boom amplitude lowering, 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 overturning torque and the stabilizing torque. In the process of constant speed amplitude lowering 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 overturning torque becomes larger as the angle becomes smaller. In the process of stopping the boom amplitude lowering, 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, and thus 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 can be provided as methods, systems, or computer program products. Therefore, the present application can 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 can adopt the form of a computer program product implemented on one or more computer-usable storage media (including but not limited to magnetic disk storage, CD-ROM, optical storage, etc.) that contain 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 produce a machine, so that the instructions executed by the processor of the computer or other programmable data processing device generate instructions for implementing the steps in the process. Figure 1one or more processes and / or blocks Figure 1 an apparatus with the functionality to achieve the specified processes or functions in the block or blocks.

[0175] These computer program instructions can also be stored in a computer-readable memory that can direct a computer or other programmable data processing apparatus to function in a Figure 1 one or more processes and / or blocks Figure 1 an apparatus with the functionality to achieve the specified processes or functions in the block or blocks.

[0176] These computer program instructions can also be loaded onto a computer or other programmable data processing apparatus to cause a series of operational steps to be performed on the computer or other programmable apparatus to produce a computer implemented process such that the instructions which execute on the computer or other programmable apparatus provide steps for implementing the processes specified in the flowchart Figure 1 one or more processes and / or blocks Figure 1 an apparatus with the functionality to achieve the specified processes or functions in the block or blocks.

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

[0178] The memory can include non-persistent memory and / or volatile memory, such as random access memory (RAM) about which the processor can execute instructions. The memory can also include non-volatile memory, such as read only memory (ROM), electrically programmable read only memory (EPROM), electrically erasable programmable read only memory (EEPROM), flash memory, or other memory technologies, about which the processor can execute instructions. The memory is an example of computer readable media.

[0179] Computer readable media includes permanent and non-permanent, removable and non-removable media implemented in any method or technology for storage of information such as 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 programmable read only memory (EEPROM), flash memory or other memory technologies, compact disc read only memory (CD-ROM), digital versatile disc (DVD) or other optical storage, magnetic cassette, magnetic tape magnetic disk storage or other magnetic storage devices, or any other non-transmission medium that can be used to store information accessible to computing devices. According to the definition herein, computer readable media does not include transitory media, such as modulated data signals and carrier waves.

[0180] It should also be noted that the terms "comprises," "includes," or any other variations thereof are intended to encompass non-exclusive inclusion, such that a process, method, commodity, or apparatus that includes a series of elements includes not only those elements but also other elements not explicitly listed, or includes elements inherent to such process, method, commodity, or apparatus. In the absence of further limitations, an element defined by the phrase "comprises a ..." does not exclude the presence of other identical elements in the process, method, commodity, or apparatus that includes the element.

[0181] The above are merely 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 modifications and variations. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principles of the present application should all be included within the scope of the claims of the present application.

Claims

1. A method for controlling an anti-rollover of a forklift, characterized in that: 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 boom's luffing and lowering speed. The anti-rollover control method includes: Acquiring handle opening information of the handle, speed information of the engine, and boom angle information of the boom; Determining the operating condition type of the boom during luffing and lowering, the operating condition type being one of a luffing and lowering start-up and acceleration operating condition, a luffing and lowering constant speed lowering operating condition, and a luffing and lowering deceleration and stop operating condition; Inputting the handle opening information, the 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 magnitude of the valve-controlled current of the solenoid valve is controlled according to a change in 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-controlled current of the solenoid valve according to a change of the second difference relative to the first difference includes: 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-controlled current is reduced.

3. The anti-rollover control method according to claim 1, characterized in that: When the determined operating condition type is the variable-range descent start and acceleration operating condition: The method of using the torque calculation model to predict a second difference between the stabilizing torque and the overturning torque at a next moment includes: determining the angular acceleration of the arm according to the handle opening information and the rotational speed information; Predicting a boom angle at a next moment based on the current boom angle and the angular acceleration of the boom; A second difference between the tilting moment and the stabilizing moment at a next moment is predicted according to the predicted boom angle and the angular acceleration.

4. 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 includes: 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-controlled current of the solenoid valve at the next moment is determined according to the optimal handle opening value.

5. The anti-rollover control method according to claim 1, characterized in that: When the determined operating condition type is the variable amplitude descent constant speed descent operating condition: The method of using the torque calculation model to predict a second difference between the stabilizing torque and the overturning torque at a next moment includes: determining an 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 based on the current boom angle and the angular velocity; A second difference between the stabilizing moment and the overturning moment at a next moment is predicted according to the predicted boom angle.

6. The anti-rollover control method according to claim 1, characterized in that: When the determined operating condition type is the variable amplitude descending deceleration stop operating condition: The method of using the torque calculation model to predict a second difference between the stabilizing torque and the overturning torque at a next moment includes: determining the angular acceleration of the arm according to the handle opening information; Predicting a boom angle at a next moment based on the current boom angle and the angular acceleration of the boom; A second difference between the stabilizing moment and the overturning moment at a next moment is predicted according to the predicted boom angle and the angular acceleration.

7. The anti-rollover control method according to claim 1, 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 includes: Obtaining 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.

8. The anti-rollover control method according to claim 1, characterized in that: The torque calculation model corresponding to the variable-luffing, lowering, starting, and accelerating working condition is associated with the boom angle, handle opening, and engine speed; The torque calculation model corresponding to the variable-luffing and 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 and stopping working condition is associated with the boom angle and the handle opening.

9. 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 8.

10. 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. The solenoid valve is used to adjust the retraction speed of the hydraulic cylinder to adjust the boom's luffing and lowering speed. The anti-rollover control device includes: an angle sensor configured to detect an angle of the boom; and A controller according to claim 9.

11. A forklift, characterized in that: include: boom; handle; engine; Hydraulic cylinder; a solenoid valve for adjusting the retraction speed of the hydraulic cylinder to adjust the boom lowering speed; and The anti-rollover control device for a forklift according to claim 10.

12. 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 8.

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