Intelligent control method and system for attitude stability of forklift loader

Abstract

The invention relates to the technical field of artificial intelligence, and discloses an intelligent control method and system for the attitude stability of a forklift loader, and the method comprises the steps: carrying out the filtering processing of the original data of a sensor of the forklift loader; calculating the actual attitude of the forklift loader by using the vehicle attitude model and the filtered original data of the sensor; calculating boundary parameters of the forklift truck according to the actual attitude, and separating stable boundaries of the attitude of the forklift truck through the boundary parameters; an attitude stability combined control strategy of the forklift loader is generated according to the separation boundary area, and a stability control instruction is generated according to the attitude stability combined control strategy; performing combined adjustment on the attitude of the forklift truck through the stability control instruction, monitoring the attitude stability of the forklift truck after combined adjustment in real time, and generating a two-dimensional annular control strategy of the attitude of the forklift truck according to the attitude stability; and the attitude stability of the forklift loader is adjusted according to the two-dimensional annular control strategy. According to the invention, the efficiency of controlling the attitude stability of the forklift loader can be improved.

Description

Technical Field

[0001] The present invention relates to the field of artificial intelligence technology, and in particular to an intelligent control method and system for the posture stability of a forklift. Background Art

[0002] In today's industrial field, intelligence has become an unstoppable development trend. All kinds of industrial equipment are moving towards automation and intelligence to improve production efficiency, reduce labor costs, and improve equipment operation safety and reliability. Forklifts, as important loading and unloading equipment in logistics, warehousing and other industries, also need to follow this trend and realize intelligent control of posture stability to improve the intelligence level of the entire industrial production process.

[0003] The existing intelligent control technology for the posture stability of forklifts relies on the driver's experience and simple mechanical control methods to maintain the stability of the forklift's posture. It is difficult for the driver to accurately judge whether the vehicle's posture is within a safe and stable range at all times while operating the vehicle, especially under complex working conditions. It is difficult to respond quickly and accurately to adjust the posture. Moreover, traditional mechanical control methods often lack flexibility and accuracy, resulting in low efficiency in controlling the forklift's posture stability. Summary of the invention

[0004] The present invention provides an intelligent control method and system for the posture stability of a forklift, the main purpose of which is to solve the problem of low efficiency when controlling the posture stability of the forklift.

[0005] To achieve the above object, the present invention provides an intelligent control method for forklift posture stability, comprising:

[0006] Collecting raw sensor data of the forklift, and filtering the raw sensor data;

[0007] The actual posture of the forklift is calculated using the pre-built vehicle posture model and the filtered raw sensor data;

[0008] Calculating a boundary parameter of the forklift according to the actual posture, separating the stability boundary of the forklift posture by the boundary parameter to obtain a separation boundary area;

[0009] generating a posture stability joint control strategy for the forklift according to the separation boundary area, and generating a stability control instruction for the forklift according to the posture stability joint control strategy;

[0010] The forklift posture is jointly adjusted by the stability control instruction, including: determining the actual posture parameter vector of the forklift according to the real-time posture of the forklift; determining the control parameter according to the stability control instruction; generating a joint adjustment function according to the actual posture parameter vector and a preset posture state variable:

[0011]

[0012] Wherein, u is the value of the joint adjustment function, u1(θ, p1) is the joint adjustment function corresponding to the stable state p1 under the actual posture parameter vector θ, u2(θ, p2) is the joint adjustment function corresponding to the critical state p2 under the actual posture parameter vector θ, u3(θ, p3) is the joint adjustment function corresponding to the dangerous state p3 under the actual posture parameter vector θ, and S is the posture state variable;

[0013] The forklift truck posture is jointly adjusted by using the joint adjustment function, and the posture stability of the forklift truck after the joint adjustment is monitored in real time, and a two-dimensional ring control strategy of the forklift truck posture is generated according to the posture stability;

[0014] The posture stability of the forklift is adjusted according to the two-dimensional ring control strategy to obtain a stable posture of the forklift.

[0015] Optionally, the filtering the raw data of the sensor includes:

[0016] Obtaining the initial state value, initial covariance matrix and initial state transfer matrix of the forklift, and generating a measurement matrix according to the raw data of the sensor;

[0017] Calculate the target state value and the target covariance matrix at the target time through the initial state transfer matrix and the initial covariance matrix;

[0018] The gain coefficient is calculated according to the real-time measurement value in the measurement matrix and the target covariance matrix, the target state value is fused with the real-time measurement value according to the gain coefficient to obtain the optimal state value, and the raw data of the sensor after filtering is determined according to the optimal state value.

[0019] Optionally, the calculating the actual posture of the forklift using the pre-built vehicle posture model and the filtered raw sensor data includes:

[0020] Determine the angle data, pressure data and acceleration data of the forklift according to the raw data of the sensor after filtering;

[0021] Generate a force balance equation and a force-moment balance equation according to the angle data, the pressure data and the acceleration data using a pre-constructed vehicle posture model;

[0022] The posture equation of the forklift is constructed according to the force balance equation and the force-moment balance equation, wherein the posture equation is:

[0023]

[0024] Among them, μ r is the rolling friction coefficient, m v is the vehicle's own mass, m g is the mass of the cargo, g is the acceleration of gravity, θ1 is the pitch angle, θ2 is the roll angle, sin is the sine function, cos is the cosine function, a′ x is the longitudinal acceleration, a′ y is the lateral acceleration, (x g ,y g ,z g ) is the coordinate of the center of gravity of the forklift, F′1 is the pressure measurement value of the first wheel, F′2 is the pressure measurement value of the second wheel, F′3 is the pressure measurement value of the third wheel, F′4 is the pressure measurement value of the fourth wheel, and F t is the traction force of the forklift, L is the vehicle length of the forklift, and W is the vehicle width of the forklift;

[0025] Calculating the center of gravity coordinates of the forklift truck using the posture equation, and determining the degree and direction of inclination of the forklift truck according to the center of gravity coordinates;

[0026] The actual posture of the forklift is determined according to the tilt degree and the tilt direction.

[0027] In order to solve the above problems, the present invention also provides an intelligent control system for forklift posture stability, the system comprising:

[0028] A data filtering module, used to collect raw sensor data of the forklift and perform filtering on the raw sensor data;

[0029] The actual posture calculation module is used to calculate the actual posture of the forklift truck using the pre-built vehicle posture model and the filtered raw sensor data;

[0030] A boundary parameter calculation module, used to calculate the boundary parameters of the forklift according to the actual posture, and separate the stable boundaries of the forklift posture by the boundary parameters to obtain a separation boundary area;

[0031] A stability control instruction generating module, used for generating a posture stability joint control strategy of the forklift according to the separation boundary area, and generating a stability control instruction of the forklift according to the posture stability joint control strategy;

[0032] A two-dimensional loop control strategy generation module, used to jointly adjust the posture of the forklift through the stability control instruction, and monitor the posture stability of the forklift after the joint adjustment in real time, and generate a two-dimensional loop control strategy for the posture of the forklift according to the posture stability;

[0033] The posture stability adjustment module is used to adjust the posture stability of the forklift according to the two-dimensional ring control strategy to obtain a stable posture of the forklift.

[0034] The embodiments of the present invention filter the collected sensor data to remove data noise and calibration deviation, thereby improving data accuracy and reliability; calculate demarcation parameters and separation boundary areas, quantify the boundary of posture stability, and clearly divide different posture state intervals to facilitate targeted control strategy formulation; generate joint control strategies and control instructions, coordinate multi-link control requirements, adapt to changes in different working conditions, and ensure the coordination of various operating links; multiple systems collaboratively optimize vehicle posture, respond to posture changes in real time, and keep the vehicle in a relatively stable state during operation; adjust the two-dimensional ring control strategy to obtain a stable posture, continuously ensure safe and stable operation of the vehicle, ensure the stability of the forklift posture from multiple aspects, and improve operation safety and efficiency. Therefore, the intelligent control method and system for the forklift posture stability proposed in the present invention can solve the problem of low efficiency when controlling the forklift posture stability. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] Figure 1 A schematic flow chart of an intelligent control method for a forklift truck posture stability provided by an embodiment of the present invention;

[0036] Figure 2 A functional module diagram of an intelligent control system for forklift posture stability provided by an embodiment of the present invention;

[0037] The realization of the purpose, functional features and advantages of the present invention will be further explained in conjunction with embodiments and with reference to the accompanying drawings. DETAILED DESCRIPTION

[0038] It should be understood that the specific embodiments described herein are only used to explain the present invention, and are not used to limit the present invention.

[0039] The embodiment of the present application provides an intelligent control method for the posture stability of a forklift. The execution subject of the intelligent control method for the posture stability of the forklift includes but is not limited to at least one of the electronic devices such as a server and a terminal that can be configured to execute the method provided by the embodiment of the present application. In other words, the intelligent control method for the posture stability of the forklift can be executed by software or hardware installed on a terminal device or a server device, and the software can be a blockchain platform. The server includes but is not limited to: a single server, a server cluster, a cloud server or a cloud server cluster, etc. The server can be an independent server, or it can be a cloud server that provides basic cloud computing services such as cloud services, cloud databases, cloud computing, cloud functions, cloud storage, network services, cloud communications, middleware services, domain name services, security services, content delivery networks (Content Delivery Network, CDN), and big data and artificial intelligence platforms.

[0040] Reference Figure 1 FIG. 1 is a flow chart of an intelligent control method for the posture stability of a forklift truck provided by an embodiment of the present invention. In this embodiment, the intelligent control method for the posture stability of a forklift truck includes:

[0041] S1. Collecting raw sensor data of a forklift truck and filtering the raw sensor data.

[0042] In the embodiment of the present invention, the sensor raw data refers to the initial measurement information directly collected by various sensors installed on the forklift, including angle sensor data, pressure sensor data and acceleration sensor data. The angle sensor data includes roll angle data and pitch angle data, the pressure sensor data includes pressure data at the wheel and pressure data at parts such as the cargo fork, and the acceleration sensor data includes longitudinal acceleration data and lateral acceleration data.

[0043] In detail, the raw sensor data of the forklift can be collected from a pre-stored storage area through a computer statement with a data capture function (such as a Java statement, a Python statement, etc.), where the storage area includes but is not limited to a database and a blockchain.

[0044] Furthermore, when the sensor collects the forklift-related status data, it will inevitably be affected by various interference factors, causing the collected raw data to contain noise. Therefore, the collected sensor raw data must be filtered to enhance the data quality of the sensor raw data.

[0045] In the embodiment of the present invention, the filtering processing technology uses the estimated value at the previous moment and the measured value at the current moment to continuously optimize the state estimation through two steps of prediction and update. It is necessary to filter the forklift posture-related sensor data (such as angle, acceleration, pressure, etc.) under various working conditions.

[0046] In the embodiment of the present invention, the filtering process of the raw data of the sensor includes:

[0047] Obtaining the initial state value, initial covariance matrix and initial state transfer matrix of the forklift, and generating a measurement matrix according to the raw data of the sensor;

[0048] Calculate the target state value and the target covariance matrix at the target time through the initial state transfer matrix and the initial covariance matrix;

[0049] The gain coefficient is calculated according to the real-time measurement value in the measurement matrix and the target covariance matrix, the target state value is fused with the real-time measurement value according to the gain coefficient to obtain the optimal state value, and the raw data of the sensor after filtering is determined according to the optimal state value.

[0050] Specifically, when the system is started, some initial values ​​need to be set, including the initial state estimate x0 (for example, the roll angle and pitch angle are set to zero according to the known posture of the vehicle when it is initially stationary on a horizontal road, and the center of gravity is set to the ideal designed position, etc.), the initial covariance matrix P0 (reasonably set according to the uncertainty of the initial state estimate, generally a relatively large value indicates that the initial state is not very certain), and the known system state transfer matrix F k―1 (Based on the vehicle kinematics and dynamics model, determine the transfer relationship between state variables at different times, such as the impact of vehicle speed changes, lifting operations, etc. on posture), measurement matrix H k (Determine the corresponding relationship between the angle, pressure and other measured values ​​and the vehicle state variables according to the sensor measurement principle and installation position), process noise covariance matrix Q k―1 (set based on past experience or analysis of vehicle model errors, unmodeled dynamics, etc.) and the measurement noise covariance matrix R k (Refer to the sensor's accuracy indicators, etc. for setting).

[0051] Specifically, as the forklift starts to operate, the sensor continuously collects data and transmits it to the control system. For example, at a certain time k, first follow the prediction step, based on the optimal state estimate and covariance of the previous moment, combined with the current control input of the vehicle (such as whether it is lifting goods, changing the driving speed, etc.), the predicted state value of the current moment is calculated through the state equation and covariance prediction equation and the prediction covariance matrix Then, the angle, pressure and other data actually measured by the sensor at the current moment are obtained to form the measurement vector z k , and then calculate the Kalman gain K according to the update step k , and use it to fuse the predicted state and the measured value to get the optimal state estimate x at the current moment k (i.e., the filtered vehicle attitude estimate, including accurate roll angle, pitch angle, center of gravity position estimation, etc.) and the updated covariance matrix P k , used for the next moment's loop filtering operation, through the Kalman filtering process, continuously optimizes the estimation of the forklift's posture, providing a high-quality data basis for subsequent posture analysis and intelligent control strategy formulation, thereby better ensuring the vehicle's posture stability under various working conditions and improving the safety and efficiency of operations.

[0052] Furthermore, forklifts face various complex working conditions in actual operations, such as driving on roads of different smoothness, loading goods of different weights and center of gravity distributions, turning, accelerating, decelerating, and lifting goods. These working conditions will have different degrees of impact on the vehicle posture, and the various influencing factors are intertwined. Based on the raw sensor data after filtering, it is possible to accurately analyze and reflect how the vehicle posture changes under the interaction of these complex working conditions, so that the operator or control system can understand the real status of the vehicle in real time.

[0053] S2. Calculate the actual posture of the forklift truck using the pre-built vehicle posture model and the filtered raw sensor data.

[0054] In the embodiments of the present invention, the pre-constructed vehicle posture model is usually based on the principle of rigid body mechanics, and regards the forklift as a rigid body, and comprehensively considers various forces and torques acting on the vehicle to describe its posture changes. The actual posture refers to the real spatial state of the forklift at a certain moment, and comprehensively considers the lateral and longitudinal inclination of the vehicle (combined by the roll angle, pitch angle and center of gravity coordinates) and the overall force and motion state of the vehicle and other factors.

[0055] In the embodiment of the present invention, the method of calculating the actual posture of the forklift truck using the pre-built vehicle posture model and the raw sensor data after filtering includes:

[0056] Determine the angle data, pressure data and acceleration data of the forklift according to the raw data of the sensor after filtering;

[0057] Generate a force balance equation and a force-moment balance equation according to the angle data, the pressure data and the acceleration data using a pre-constructed vehicle posture model;

[0058] The posture equation of the forklift is constructed according to the force balance equation and the force-moment balance equation, wherein the posture equation is:

[0059]

[0060] Among them, μ r is the rolling friction coefficient, m v is the vehicle's own mass, m g is the mass of the cargo, g is the acceleration of gravity, θ1 is the pitch angle, θ2 is the roll angle, sin is the sine function, cos is the cosine function, a′ x is the longitudinal acceleration, a′ y is the lateral acceleration, (x g ,y g ,z g ) is the coordinate of the center of gravity of the forklift, F′1 is the pressure measurement value of the first wheel, F′2 is the pressure measurement value of the second wheel, F′3 is the pressure measurement value of the third wheel, F′4 is the pressure measurement value of the fourth wheel, and F t is the traction force of the forklift, L is the vehicle length of the forklift, and W is the vehicle width of the forklift;

[0061] Calculating the center of gravity coordinates of the forklift truck using the posture equation, and determining the degree and direction of inclination of the forklift truck according to the center of gravity coordinates;

[0062] The actual posture of the forklift is determined according to the tilt degree and the tilt direction.

[0063] In detail, the vehicle posture model includes elements such as the vehicle's own weight, cargo weight, ground support force, inertia force, and friction force. For example, for the longitudinal posture (pitch direction) of the vehicle, with the front and rear axles of the vehicle as reference, when establishing the moment balance equation, it is necessary to consider the moment generated by the vehicle's own weight, the moment generated by the cargo at different lifting heights and front and rear positions, the moment of the inertia force generated during the acceleration or deceleration of the vehicle, and the moment of the ground support force given to the vehicle through the tires. Similarly, in the lateral posture (roll direction), the corresponding equation needs to be constructed based on the force and moment conditions on the left and right sides of the vehicle.

[0064] Specifically, the angle data includes roll angle and pitch angle, which directly reflect the degree of inclination of the vehicle in the lateral and longitudinal directions relative to the horizontal plane. The filtered roll angle measurement value is θ2, which can intuitively indicate the current inclination angle of the vehicle in the left and right directions. A positive value indicates a tilt to the right, and a negative value indicates a tilt to the left. Similarly, the pitch angle measurement value θ1 reflects the tilt of the vehicle in the front and rear directions. A positive value means that the front of the vehicle is lifted up, and a negative value means that the front of the vehicle is sunken. The pressure data is the filtered measurement data of the pressure sensors installed on the wheels, cargo forks and other parts. Taking the pressure sensor data at the wheels as an example, it is assumed that the filtered pressure values ​​at the four wheels are F′1, F′2, F′3, and F′4, which correspond to the actual measurement values ​​of the ground support force on the left front wheel, right front wheel, left rear wheel, and right rear wheel of the vehicle, respectively. The acceleration data reflects the changes in the acceleration of the vehicle during driving and operation, mainly involving the longitudinal acceleration a′ in straight-line driving. x The lateral acceleration a′ generated by steering and other operations y .

[0065] Furthermore, according to the principle of vertical force balance of the vehicle as a whole, the sum of the vehicle's own weight and the cargo's weight is equal to the sum of the ground support forces on the four wheels, and the vertical force balance is obtained as F'1+F'2+F'3+F'4=(m v +m g )g, when the vehicle accelerates in the longitudinal direction, in addition to considering the vehicle's own weight, cargo gravity and the longitudinal component of the wheel support force, the inertia force must also be considered. The balance of the longitudinal (x-axis) force is F t ―F f ―(m v +m g )a′ x =0, and F f =μ r (F′1+F′2+F′3+F′4), and the lateral moment balance (around the x-axis, considering the roll angle) is The longitudinal moment balance equation (around the y-axis, considering the pitch angle) is: The above-arranged equations are constructed into a matrix form Ax=b, where A is the coefficient matrix and x is the unknown vector (including x g ,y g ,z g ), b is a constant term vector, so as to obtain the coordinate x of the center of gravity of the vehicle in the vehicle coordinate system g ,y g ,z gThe specific value of the vehicle's lateral and longitudinal tilt degree and direction can be directly determined based on the center of gravity coordinates and the filtered roll angle θ2 and pitch angle θ1. By solving the linear equations through matrix operations, based on the force and torque balance relationship in the vehicle posture model and the actual measured sensor data, the key actual posture parameter of the vehicle's center of gravity position can be quantitatively determined, providing an important basis for subsequent comprehensive evaluation of the forklift's posture stability and other work.

[0066] Furthermore, according to the calculated actual posture of the forklift, it is necessary to determine the state of the forklift's posture, so as to collect different stabilization measures according to different states to keep the forklift in a stable state.

[0067] S3. Calculate the boundary parameters of the forklift according to the actual posture, separate the stability boundaries of the forklift posture by using the boundary parameters, and obtain a separation boundary area.

[0068] In the embodiment of the present invention, the boundary parameter refers to a key indicator value used to distinguish different posture stability states of the forklift, such as the boundary between a stable state indicator and a critical state indicator, and the boundary between a critical state indicator and a dangerous state indicator.

[0069] In the embodiment of the present invention, the step of calculating the boundary parameter of the forklift according to the actual posture includes:

[0070] S21, extracting static vehicle attributes and dynamic vehicle attributes corresponding to the actual posture;

[0071] S22, calculating the demarcation value of the forklift according to the static vehicle attributes and the dynamic vehicle attributes, wherein the demarcation value calculation formula is:

[0072]

[0073] Among them, R1 is the first dividing value, R2 is the second dividing value, and m s is the frame mass of the forklift, L is the vehicle length of the forklift, g is the acceleration of gravity, h1 is the height of the center of mass of the forklift, is the frame tilt angle, a′ y is the lateral acceleration, h x is the vertical distance between the forklift's center of mass and the steering axle's articulation axis, m v is the vehicle's own mass, b is the horizontal distance from the center of mass to the rear axle, B1 is the front wheel track, and B2 is the rear wheel track;

[0074] S23: Determine the first demarcation value and the second demarcation value as demarcation parameters of a forklift truck.

[0075] Specifically, static vehicle attributes are parameters related to the relatively fixed (not changing in real time with the vehicle's operating state in the short term) characteristics of the forklift's structure and mass distribution. For example, the frame mass m of the forklift s , vehicle length L, height of the forklift's center of mass h1, vertical distance between the forklift's center of mass and the steering axle's articulation axis h x , the horizontal distance b from the center of mass to the rear axle, the front wheel track B1 and the rear wheel track B2 are all static vehicle attributes. The frame mass reflects the weight of the vehicle frame. The vehicle length determines the overall size of the vehicle. The center of mass height reflects the height of the vehicle's center of gravity in the vertical direction relative to the ground or the vehicle reference plane. The vertical distance h between the forklift's center of mass and the steering axle articulation axis x It is the vertical distance between the overall center of mass of the forklift and the plane where the steering axle articulation axis is located. The horizontal distance b between the center of mass and the rear axle refers to the distance between the overall center of mass of the forklift and the center line of the rear axle (usually the rear axle of the vehicle, which often plays a supporting and driving role, depending on the vehicle drive form) in the horizontal direction. These parameters are basically fixed after the vehicle is designed and manufactured. They are the basic conditions for analyzing the stability of the vehicle's posture. They affect the stability of the vehicle in different postures from the structural and mass distribution levels; dynamic vehicle attributes are parameters related to the motion state of the vehicle during operation, which will change in real time with the vehicle's driving, steering, lifting of goods and other operations, such as the frame roll angle. and lateral acceleration a′ y The frame roll angle belongs to this type of attribute. It intuitively reflects the degree of inclination of the vehicle in the lateral direction. Its value and change reflect the instantaneous posture change of the vehicle when it is turning and subjected to lateral forces (such as side winds, lateral interference caused by uneven road surface, etc.); the lateral acceleration also represents the effect of the lateral force acting on the vehicle. It is a key indicator for measuring the lateral dynamic stability of the vehicle. For example, when the vehicle turns at a faster speed, the lateral acceleration will increase, thereby affecting the actual posture and stability of the vehicle.

[0076] Specifically, since the forklift frame is fixed to the front axle and the rear axle is hinged, there are two stages in the roll process. In the first stage, due to the large roll angle, the limit block fixed to the frame contacts the rear axle, and the single front wheel always leaves the ground first. In the second stage, the roll angle of the forklift continues to increase, and the forklift deteriorates from single front wheel off the ground to both wheels on one side off the ground. At this time, the risk of rollover is generally difficult to avoid. The demarcation value of the forklift is calculated based on the static vehicle properties and dynamic vehicle properties, and R1 and R2 are the boundary parameters of the forklift's rollover risk under different loads and working conditions. R1 and R2 are the "critical values" of the stability of the forklift in different states. R1 and the front wheel R1 is related to B1, which indicates the stability of the forklift at the front, which is usually related to the support force of the front wheels of the forklift and the length of the vehicle. R2 is related to B2, which indicates the stability of the forklift at the rear, which is usually related to the support force of the rear wheels of the forklift and the length of the vehicle. B1 and B2 represent the front wheel track and the rear wheel track respectively. The front wheel track affects the stability of the forklift at the front, while the rear wheel track affects the stability of the forklift at the rear. A larger wheel track usually provides better stability, especially when turning. The calculated R1 and R2 dividing values ​​can be used to analyze the stability of the forklift under different loads and speeds, especially when turning or operating quickly, to prevent the forklift from tipping over.

[0077] Furthermore, the area to which the forklift belongs can be determined based on the boundary parameters, and the stable, critical and dangerous areas of the vehicle can be distinguished according to different preset boundary ranges. Therefore, based on the comparison between the real-time posture parameters of the vehicle and these areas, the state category of the vehicle posture can be clearly known, so as to take targeted countermeasures.

[0078] In the embodiment of the present invention, the separation boundary area is a concept of quantifying and zoning the vehicle posture stability. It is a collection of areas that can distinguish different posture stability states of the vehicle, such as stable, critical, and dangerous, divided according to different boundary ranges based on the boundary parameters of the forklift.

[0079] In the embodiment of the present invention, the separation of the stability limits of the forklift posture by the boundary parameter to obtain the separation boundary area includes:

[0080] S31, when the boundary parameter meets the preset first target boundary range, dividing the stable domain boundary line according to the boundary parameter, and generating the stable domain boundary area according to the stable domain boundary line;

[0081] S32, when the boundary parameter meets the preset second target boundary range, dividing a critical boundary line according to the boundary parameter, and generating a critical domain boundary area according to the critical boundary line;

[0082] S33, when the boundary parameter meets the preset third target boundary range, dividing the danger zone boundary line according to the boundary parameter, and generating the danger zone boundary area according to the danger zone boundary line;

[0083] S34, merging the stable domain boundary area, the critical domain boundary area and the dangerous domain boundary area into a separation boundary area.

[0084] In detail, when the first demarcation value and the second demarcation value in the boundary parameter meet the preset first target boundary range, the posture of the forklift is considered to be in the stable domain. The stable domain is the "safe area" when the forklift is operating, indicating that the forklift will not roll over or become unstable in this state. The boundary line of the stable domain is based on the maximum roll angle, maximum lateral acceleration and other parameters that the forklift can withstand under normal working conditions. The boundary area of ​​the stable domain represents the area where the forklift can maintain a stable posture under various operating conditions. As long as the forklift is in this area, its posture and operation will not cause instability. The preset first target boundary range refers to a range of values ​​determined based on the design parameters, safety standards, and a large amount of actual tests and empirical data of the forklift. Within this range, the posture of the forklift is considered to be in a stable state, and the various parameters of the vehicle (such as force, angle, acceleration, etc.) are in a reasonable range, and the operation can be carried out normally and safely. There is no possibility of safety risks such as rollover and loss of control caused by posture problems.

[0085] Specifically, the second target boundary range is also a pre-set parameter value interval, which is the critical state of the forklift's posture approaching instability. When the value of the dividing parameter (such as R1 and R2) is in this range, it means that although the vehicle has not yet reached the dangerous level of instability, it is already close to a state where problems such as rollover and loss of control may occur. The critical boundary line is drawn based on the operating parameters of the forklift (such as the maximum allowable roll angle, acceleration, etc.), and is located between the stable domain and the dangerous domain, indicating that the forklift is in a state close to the limit, and the critical domain boundary area indicates that the forklift may become unstable in this area, and special care must be taken when operating. At this time, the stability margin of the forklift is small, and improper operation may cause rollover or rollover; the third target boundary range is to define the parameter value range of the forklift posture in a dangerous and unstable state. When the boundary parameter falls into this range, it indicates that the vehicle is in a state where serious safety accidents such as rollover and loss of control are likely to occur. Emergency control measures (such as emergency braking, lowering cargo, etc.) must be taken immediately to avoid accidents as much as possible or reduce the degree of harm of accidents to ensure the safety of personnel and vehicles. The dangerous boundary line is defined according to the extreme conditions such as the roll angle and acceleration of the forklift under extreme conditions, and the dangerous and domain boundary area means that once the forklift enters the dangerous domain, the operation is extremely dangerous and may even cause serious accidents or rollovers. At this time, the stability of the forklift is very poor, and any improper operation may cause the vehicle to become unstable. After the stability of the forklift is divided into regions according to the boundary parameters, the stable domain boundary area, the critical domain boundary area and the dangerous domain boundary area are obtained. The three areas are merged into a separation boundary area to achieve real-time judgment of the stability state of the vehicle according to the posture and working conditions of the forklift in actual operation, and timely adjust the operation or take countermeasures.

[0086] Furthermore, the posture stability of the forklift is an important factor in ensuring that the forklift does not become unstable or overturn during operation. By defining separation boundary areas (such as the boundary between the stable domain and the unstable domain), the safe operation of the forklift under different working conditions can be ensured, and different control strategies can be generated according to different boundary areas, so that the forklift is always within a stable range under various operating conditions, thereby avoiding danger due to exceeding the safety range.

[0087] S4. Generate a posture stability joint control strategy for the forklift according to the separation boundary area, and generate a stability control instruction for the forklift according to the posture stability joint control strategy.

[0088] In the embodiment of the present invention, the posture stability joint control strategy refers to the control strategies of the three key operations of driving, lifting and braking cooperating with each other and working in coordination during the entire posture stability joint control process.

[0089] In an embodiment of the present invention, the generating of a posture stability joint control strategy of a forklift according to the separation boundary area includes:

[0090] Determining driving data, lifting data and braking data of the forklift according to each boundary area in the separation boundary area;

[0091] generating a driving control strategy for each boundary area according to the driving data, generating a lifting control strategy for each boundary area according to the lifting data, and generating a braking control strategy for each boundary area according to the braking data;

[0092] A posture stability joint control strategy of the forklift in each boundary area is determined according to the driving control strategy, the lifting control strategy and the braking control strategy.

[0093] In detail, the boundary area includes a stable area, a critical area and a dangerous area, and the driving control strategy, lifting control strategy and braking control strategy are determined in the stable area, the critical area and the dangerous area respectively, and the driving control strategy includes the driving speed and driving steering parameters; the lifting control strategy includes the lifting speed and the change of the vehicle's center of gravity during the lifting process; the braking control strategy includes braking mode data, so that the driving control strategy, lifting control strategy and braking control strategy corresponding to the stable area, the critical area and the dangerous area are determined as the joint control strategy for the posture stability of the forklift.

[0094] Specifically, in the stable area, the driving control strategy includes determining the appropriate driving speed range based on the vehicle's rated load, road conditions, and pre-set standard operating parameters. For example, when the vehicle is unloaded and driving on a flat hard road, the vehicle speed can be maintained at 15-20km / h; when loaded with goods, the vehicle speed is reduced in proportion to the weight of the goods, such as when loading medium-weight goods (accounting for about 50% of the vehicle's rated load), the vehicle speed is maintained at 10-15km / h, ensuring that the inertial force generated by the vehicle's driving will not cause the posture parameters to have the risk of exceeding the stability limit, and setting reasonable steering parameters, the steering angular velocity is controlled at no more than 10° per second, and the steering angle is no more than 25° per operation, ensuring that the steering action is smooth and gentle, avoiding excessive lateral acceleration caused by sharp steering, and making the lateral posture parameters such as the roll angle always within the stable range; in the lifting control strategy, a reasonable lifting speed curve is planned according to the design lifting capacity of the cargo fork and the stability requirements of the overall vehicle structure. In the initial stage of lifting, the lifting speed can be set to 0.1-0.15 meters per second; as the lifting height of the cargo increases, the lifting speed is gradually reduced. When approaching the maximum lifting height, the speed is adjusted to 0.05-0.1 meters per second to avoid rapid changes in the center of gravity of the vehicle due to excessive lifting, which in turn causes the pitch angle and other attitude parameters to exceed the stable range. During the lifting process, the change in the center of gravity position of the vehicle is calculated continuously through the data fed back by the pressure sensor. Once the longitudinal or lateral offset of the center of gravity is found to be close to the corresponding stable limit, the driver is promptly reminded to pay attention to the distribution of the center of gravity of the cargo through the human-computer interaction interface, and specific adjustment suggestions can be given (such as if the center of gravity of the cargo is slightly backward, please move the cargo forward appropriately) to ensure that the center of gravity of the vehicle is always in a reasonable and stable range; when braking is required for normal driving in the braking control strategy, a smooth and gradual braking method is adopted. According to factors such as vehicle speed and distance from the vehicle in front or obstacles, the braking force is reasonably adjusted, and the braking deceleration is controlled within the conventional safety range that the vehicle can withstand, for example, the maximum braking deceleration does not exceed 1.2m / s 2 , to prevent the longitudinal acceleration caused by sudden braking from causing the vehicle's pitch angle, longitudinal center of gravity position and other posture parameters to exceed the stability limit.

[0095] For example, in the critical area, when the driving control strategy detects that one or more posture parameters of the vehicle are close to but have not exceeded the corresponding limit value (for example, the roll angle reaches 80% of the boundary value of its stable range, if the roll angle stable range is ±1.5°, the actual roll angle reaches ±1.2°), the speed adjustment mechanism is immediately activated to reduce the current vehicle speed to about 60%-70% of the original speed. If the original vehicle speed is 15km / h, it is adjusted to 9-10km / h, so as to reduce the influence of the inertial force generated by the speed during driving on the posture stability, and prevent the parameters from further deteriorating and exceeding the critical state. In the lifting control strategy, if a lifting operation is in progress, once the vehicle enters a critical posture state, the lifting action is immediately suspended to observe the trend of posture parameter changes, and detailed feedback on cargo center of gravity adjustment suggestions is given to the driver through the vehicle system. For example, if the cargo center of gravity is slightly to the left, it is recommended to slightly adjust the cargo position to the right to optimize the vehicle. The center of gravity distribution is adjusted to make the posture parameters return to a safer and more stable range; the braking operation in the braking control strategy is switched to a softer and more gradual method, and the braking deceleration is controlled at about 50%-60% of the original conventional maximum allowable value. In the dangerous area, when the driving control strategy detects that the vehicle's posture parameters exceed the corresponding limit values ​​(for example, the roll angle is greater than ±1.5° of its stable range), the emergency braking procedure is immediately initiated, and the vehicle is braked at the maximum deceleration that it can safely withstand, and the steering system is immediately locked, prohibiting conventional manual steering operations by the driver, but allowing the control system to be based on the vehicle's posture sensor. The vehicle automatically corrects small angles (e.g., each correction angle does not exceed 3°) based on the data fed back by the sensor. The purpose is to assist the vehicle in restoring a stable posture as much as possible during emergency braking, avoid serious accidents such as rollover, and prioritize ensuring that the vehicle decelerates in a straight line. In the lifting control strategy, if the cargo fork is in the lifting state, the cargo fork is quickly controlled to lower the cargo at a faster and safe speed to reduce the overall center of gravity of the vehicle as soon as possible. In the braking control strategy, anti-skid and posture recovery are coordinated to automatically and intelligently adjust the braking force distribution of each wheel to prevent the wheel from locking and slipping, and make full use of the adhesion between the wheel and the ground to achieve effective braking.

[0096] Furthermore, in the whole process of joint control of attitude stability, the control strategies of the three key operations of driving, lifting and braking cooperate with each other and work in coordination. For example, when the driving control system determines that the vehicle attitude has entered a critical state and reduces the speed, it will send coordination signals to the lifting and braking control systems at the same time. The lifting control system will suspend or slow down the lifting operation accordingly, and the braking control system will switch to a soft braking mode accordingly; and when the vehicle attitude is in an unstable state, the various control systems will work closely together and obey the emergency control instructions in a unified manner to jointly ensure that the vehicle can restore a stable attitude as soon as possible.

[0097] Furthermore, the posture stability joint control strategy needs to be flexibly adjusted and optimized according to the specific control system architecture, hardware configuration and sensor feedback of the forklift, so it is necessary to generate control instructions, and the instructions need to be coordinated with each other to ensure the safety and stability of the forklift's operation in different postures.

[0098] In the embodiment of the present invention, the stability control instructions cover the main operating links such as vehicle driving, lifting, braking, etc., and the instruction set for the goal of maintaining the stability of the vehicle posture is generated based on the posture stability joint control strategy, which is used to command the operation of various related systems of the forklift to achieve the purpose of maintaining the stability of the vehicle posture. It is a comprehensive instruction set covering various operating requirements. It is the key basis for achieving active and precise control of the forklift posture. By executing these instructions through various systems, the vehicle can maintain a safe and stable posture state in different operating scenarios.

[0099] In an embodiment of the present invention, the step of generating a stability control instruction for a forklift truck according to the posture stability joint control strategy includes:

[0100] Determine a driving speed command and a steering command according to the driving control strategy in the posture stability combined control strategy, determine a lifting speed command and a center of gravity monitoring command according to the lifting control strategy, and determine a braking mode command according to the braking control strategy;

[0101] Generate a driving control instruction according to the driving speed instruction and the steering instruction, generate a lifting control instruction according to the lifting speed instruction and the center of gravity monitoring instruction, and generate a braking control instruction according to the braking mode instruction;

[0102] The travel control instruction, the lifting control instruction and the braking control instruction are packaged into a stability control instruction of the forklift.

[0103] In detail, the driving control strategy is to set corresponding speed control rules for different vehicle posture states (such as stable state, critical state, unstable state), and the driving control instructions are to clarify specific speed-related operation requirements based on the speed control rules in these different scenarios, such as setting the target vehicle speed, how to adjust the vehicle speed (constant speed, deceleration, etc.), and under what conditions (such as changes in posture parameters) to adjust the vehicle speed. Its essence is to provide specific instructions for speed regulation of the vehicle power system; the steering instruction is refined according to these specific steering operation restrictions and requirements, and clearly informs the steering system how to handle the driver's operation, when to limit steering, and the allowed steering range; the lifting speed instruction is to clarify the specific value of the lifting speed under different postures and how to dynamically adjust it, so as to ensure the vehicle posture during the lifting process. The center of gravity monitoring instruction is the specific implementation of how to obtain the vehicle's center of gravity position information in real time, through the pressure sensors and other equipment installed in the key parts of the vehicle (such as wheels, cargo forks, etc.), it stipulates how often the pressure data should be collected, and clearly specifies how to send prompt information to the driver or pass the center of gravity data to other control systems (such as driving and braking systems) when the center of gravity offset is close to the stability limit, so as to jointly maintain the stability of the vehicle's posture; the braking mode instruction is based on the braking requirements under these different states, and clearly tells the braking system when to start braking, which braking mode to use (conventional braking, soft braking, emergency braking, etc.), how to adjust the braking pressure to achieve the corresponding braking deceleration, etc. It is the specific instruction content that directs the braking system to work to maintain the stability of the vehicle's posture.

[0104] Specifically, control instructions are generated in stable areas, critical areas and dangerous areas. The lifting operation directly affects the change of the center of gravity, and the change of the center of gravity in turn restricts operations such as the lifting speed. The braking control instructions will comprehensively consider multiple factors such as the vehicle's real-time posture state, vehicle speed, distance to the vehicle in front, etc., and clarify the specific working mode of the braking system in various situations according to the braking method instructions (such as conventional braking, soft braking, and the specific triggering conditions and execution process of emergency braking), to ensure that the braking process can not only achieve effective deceleration, but also ensure that the vehicle's posture will not deteriorate due to braking operations.

[0105] For example, in the stable area control command, the driving control command includes a speed command and a steering command, and the speed command includes a command number S-Speed-001, and the command content is to query a preset speed reference table to determine the appropriate speed according to the current vehicle load and road conditions. If the vehicle is unloaded and the road is flat, the target speed is set to 18km / h; if the vehicle is loaded with medium-weight cargo (accounting for about 50% of the rated load) and the road conditions are good, the target speed is set to 12km / h. The speed regulation module of the power system is used to control the speed of the drive motor or engine to keep the vehicle speed stable at the set value. The allowable speed fluctuation range is ±0.5km / h. The execution condition is that the vehicle is started and the posture parameters are in a stable area, there are no abnormal angle and acceleration changes, and there is no external emergency intervention signal; the steering command includes the command number S-Steer-001, and the command content is to set the steering angular velocity limit of the steering system to no more than 10° per second, and the maximum single steering angle is no more than 25°. The steering controller monitors the steering wheel operation angle and angular velocity. When the driver turns the steering wheel, the input signal is filtered and smoothed to ensure that the actual steering action meets the set limits, ensure a smooth steering process, and avoid excessive lateral acceleration. The execution condition is that the vehicle is in a driving state and the posture parameters are stable, and no warning signal of an approaching critical or unstable state is received; the lifting speed command in the lifting control command includes the command number S-Lift-001, and the command content is to set the lifting speed limit in the lifting operation. In the initial stage of operation, the flow rate of hydraulic oil is controlled by the flow regulating valve of the lifting hydraulic system to keep the lifting speed of the cargo fork at 0.12 meters per second. As the lifting height increases, according to the feedback data of the height sensor, when the lifting height reaches 50% of the total lifting height, the flow regulating valve opening is gradually reduced to linearly reduce the lifting speed to 0.08 meters per second; when approaching the maximum lifting height (reaching 90% or more of the total lifting height), the flow regulating valve is further adjusted to maintain the lifting speed at 0.05 meters per second to ensure that the center of gravity of the vehicle changes steadily and the posture is stable during the lifting process. The execution conditions are that the lifting operation start signal is received and the vehicle posture is in a stable area, and there is no abnormal fluctuation in the data of each posture sensor. The center of gravity monitoring instruction includes an instruction number S-Center-001, and the instruction content is to collect pressure data every 0.1 seconds through pressure sensors installed at key parts such as wheels and cargo forks, and calculate the longitudinal and lateral positions of the center of gravity of the vehicle in real time based on the preset center of gravity calculation model.If the longitudinal or lateral offset of the center of gravity is close to 80% of the corresponding stability limit (for example, the longitudinal center of gravity offset stability limit is 0.5 meters, when the offset reaches 0.4 meters), the center of gravity offset warning information is sent to the driver through the on-board human-computer interaction interface, prompting that the center of gravity of the cargo is slightly biased to the rear, and the center of gravity data is transmitted to other related control systems (such as driving, lifting, and braking systems) to facilitate coordinated adjustment of the control strategy. The execution conditions are that the vehicle is in an operating state (including driving, lifting, etc.) and the posture is stable, and the sensor is working normally; the braking control command includes a conventional braking command, the command number is S-Brake-001, and the command content is that when braking is required during normal driving, when the driver steps on the brake pedal or receives an automatic braking trigger signal (such as when the distance to the vehicle in front is too close, etc.), the braking system controls the brake pressure adjustment device through the electronic control unit (ECU) according to comprehensive factors such as vehicle speed, pedal travel, and distance to the vehicle in front, and increases the braking force in a linear and gentle manner, and the braking deceleration is controlled to a maximum of no more than 1.2m / s. 2 The execution conditions are that the vehicle is in a driving state and the posture is stable, a braking demand signal is received, and no emergency braking signal is involved.

[0106] Furthermore, based on the stability control instructions generated under different posture states (stable, critical, unstable) of the forklift, the vehicle posture parameters are monitored in real time through the control system, and according to the range of these parameters, the relevant subsystems (driving, lifting, braking, etc.) are coordinated to execute corresponding control instructions to form a feedback adjustment mechanism, so as to achieve precise joint adjustment of the forklift posture, ensure that the vehicle can maintain a stable posture under various working conditions, and avoid safety problems such as rollover and loss of control.

[0107] S5. The posture of the forklift truck is jointly adjusted through the stability control instruction, and the posture stability of the forklift truck after the joint adjustment is monitored in real time, and a two-dimensional circular control strategy of the posture of the forklift truck is generated according to the posture stability.

[0108] In the embodiment of the present invention, based on the stability control instructions generated under different postures (stable, critical, unstable) of the forklift, the relevant subsystems (driving, lifting, braking, etc.) are coordinated to execute corresponding control instructions to form a closed-loop feedback adjustment mechanism to achieve precise joint adjustment of the forklift posture, thereby ensuring that the vehicle can maintain a stable posture under various working conditions and avoiding safety problems such as rollover and loss of control.

[0109] In the embodiment of the present invention, the joint adjustment of the posture of the forklift truck by the stability control instruction includes:

[0110] Determine an actual posture parameter vector of the forklift according to the real-time posture of the forklift;

[0111] determining a control parameter according to the stability control instruction;

[0112] Generate a joint adjustment function according to the actual posture parameter vector and the preset posture state variable:

[0113]

[0114] Wherein, u is the value of the joint adjustment function, u1(θ, p1) is the joint adjustment function corresponding to the stable state p1 under the actual posture parameter vector θ, u2(θ, p2) is the joint adjustment function corresponding to the critical state p2 under the actual posture parameter vector θ, u3(θ, p3) is the joint adjustment function corresponding to the dangerous state p3 under the actual posture parameter vector θ, and S is the posture state variable;

[0115] The joint adjustment function is used to jointly adjust the posture of the forklift.

[0116] In detail, the posture of the forklift is represented by the variable S, S = 1 represents a stable state, S = 2 represents a critical state, and S = 3 represents an unstable state; the actual posture parameter vector of the vehicle is θ = {θ1, θ2, x g ,y g ,a′ x ,a′ y}, where θ2 is the roll angle, θ1 is the pitch angle, and x g is the longitudinal coordinate of the vehicle's center of gravity, y g is the lateral coordinate of the vehicle's center of gravity, a′ x is the longitudinal acceleration, a′ y is the lateral acceleration; the control parameter vector corresponding to each control instruction is u=[u speed ,u steer ,u lift ,u brake ] T , respectively represent the driving speed control amount, steering control amount, lifting control amount, and braking control amount.

[0117] Specifically, the control amount calculation u1(θ, p1) in the stable state is first calculated by calculating the driving speed control amount u speed , the target speed v is determined according to the vehicle load m (including cargo) and the road condition level r (e.g. r = 1 for a flat hard road, r = 2 for a slightly bumpy road, etc.) target , assuming that there is the following relationship v target =v0+k1m+k2r, where v0 is the basic vehicle speed constant, k1 and k2 are the corresponding coefficients; the PID controller is used to adjust the power system speed n to maintain the vehicle speed stable at v target Nearby, discrete form of PID control formula (sampling period is T) Among them, u speed (k) is the speed control value at the kth sampling moment, They are the proportional, integral and differential coefficients of speed control in the stable state, e v (k) = v target ―v(k) is the speed error at the kth sampling moment, v(k) is the actual speed; and the steering control amount u steer Limiting the steering angle speed and single turn angle The steering angle velocity ω input by the driver in and the steering angle θ in Actual steering angular velocity after filtering and smoothing and angle The calculation of

[0118] but It can be set to the maximum allowable angular velocity value under the corresponding stable state. is the maximum allowable angle value, then Lifting control amount u lift During the lifting process, the lifting speed v is controlled in stages according to the lifting height h lift , assuming that the lifting height is divided into three intervals h1 and h2 (for example, h1 is 50% of the total lifting height, h2 is 90%), then where v lift1 、v lift2 、v lift3 are the lifting speed values ​​set at each stage. The lifting speed control is achieved by adjusting the flow Q of the lifting hydraulic system. Assuming that the piston area of ​​the lifting cylinder is A, then Q = Av lift , so u lift =Q; braking control amount u brake , during normal braking, the braking deceleration is a brake According to factors such as vehicle speed v, brake pedal travel s, and distance d from the vehicle in front, the following relationship is obtained: To control a brake The maximum permissible value in steady state Within, it is achieved by adjusting the brake pressure P through the electronic control unit (ECU), then u brake =P, and satisfies the constraint By adjusting P, the braking process is smooth and the posture is guaranteed to be stable.

[0119] Furthermore, the control amount under the critical state is calculated as u2(θ,p2), then the driving speed control amount u speed Indicates that when the posture is in a critical state, the vehicle speed v is reduced to the original speed v originalA certain proportion α (determined according to the degree to which the posture parameter approaches the critical value), that is, v adjusted =αv original , speed adjustment is also achieved by adjusting the speed n through the PID controller; the steering control amount u steer Further tighten the steering limit, set the maximum steering angular velocity v under critical state xx , the maximum single turning angle is The actual steering angular velocity after the steering operation is processed and angle Calculate, then Lifting control amount u lift If you are lifting cargo, stop lifting first (i.e. lift =0), keep the current height of the fork unchanged. If the posture parameters show signs of improvement and are not close to the lifting limit, the lifting speed v′ can be increased. lift Adjust to 0.03-0.08 meters per second, also achieved by adjusting the flow rate Q, that is, Q = Av' lift , dynamically determine v′ according to the posture parameters lift The specific value of u lift =Q, and the attitude parameter changes should be continuously monitored to prevent the attitude from entering an unstable state due to lifting; the braking control amount u brake Indicates the braking deceleration a′ brake Controlled within the original conventional maximum allowable value a max 50%-60% of the total value, assuming the proportionality coefficient is β (ranging from 0.5 to 0.6), then a′ brake =βa max , the ECU adjusts the brake pressure P' according to factors such as vehicle speed v, distance d to the vehicle in front, and current posture parameters to achieve a' brake control, that is Then u brake =P′, and satisfies a′ brake ≤βa max , so as to finely control the braking and prevent the posture from exceeding the critical value. The control amount in the unstable state is calculated u3(θ,p3), and the driving speed control amount u speed Initiate emergency braking in an unstable state with the maximum deceleration a″ that the vehicle can safely withstand max The power system cuts off the power output of the drive motor or engine, making the drive wheel torque zero, and adjusts the brake pressure P″ through the brake system to achieve the maximum deceleration a″ max , that is, a′ n ' ax =f(P″), and u speed It is mainly reflected in the regulation and control of the brake pressure P″, so that the vehicle can be decelerated to a relatively safe state as soon as possible; the steering control amount usteer Lock the steering system, prohibiting the driver from performing manual steering operations, but allowing the control system to make small steering corrections based on the feedback data from the vehicle attitude sensor. Assume that the actual roll angle is θ2 and the expected stable roll angle is (usually 0), each steering correction angle Δθ does not exceed 3°, then where k s is the correction coefficient, at this time u steer =Δθ, through automatic small angle correction to assist the vehicle to restore stable posture during emergency braking, ensuring deceleration in a straight line; lifting control amount u lift It means that if the cargo fork is in the lifting state, the cargo fork is controlled to lower the cargo at a speed of 0.2-0.25 meters per second, which is achieved by adjusting the flow Q″ of the lifting hydraulic system, that is, The size of Q″ is determined according to the set drop speed range, so u lift =Q″, and at the same time, the cargo lowering process should be monitored in real time through sensors to ensure smooth lowering. If an abnormal situation occurs (such as cargo stuck, etc.), the cargo lowering operation should be stopped immediately; the braking control amount u brake Indicates that the Electronic Stability Control System (ESC) intervenes and adjusts the vertical load F of each wheel. z1 、F z2 、F z3 、F z4 (can be obtained or estimated by pressure sensor) and the total braking force F b , adjust the braking force distribution of each wheel, set the ideal braking force distribution coefficients (based on vehicle dynamics theory and experience) to k1, k2, k3, k4, and the braking force F of each wheel b1 、F b2 、F b3 、F b4 ,like At the same time, ESC dynamically adjusts the braking force distribution coefficient k according to the roll angle θ2, pitch angle θ1 and other attitude parameters fed back by the vehicle attitude sensor. i , in order to achieve better braking and restore the vehicle posture by utilizing the adhesion between the wheels and the ground, so u brake ={F b1 , F b2 , F b3 , F b4}.

[0120] Furthermore, the posture stability of the forklift is not static, but is in dynamic change. It will switch between different states such as stable, critical, and unstable. It is necessary to establish a real-time feedback mechanism, adjust the control strategy in time, and dynamically adjust the vehicle posture to reflect the technicality and flexibility of posture stability control.

[0121] In the embodiment of the present invention, the two-dimensional circular control strategy is a control strategy with cyclic and closed-loop feedback characteristics that integrates open-loop control conditions (stable state) and closed-loop control conditions (unstable state). It is constructed from a two-dimensional perspective, so that the forklift truck can maintain a stable state as much as possible regardless of whether it is in normal operation or in the event of abnormal posture, thereby ensuring safe and efficient vehicle operation.

[0122] In an embodiment of the present invention, the two-dimensional circular control strategy for generating a forklift posture according to the posture stability includes:

[0123] When the posture stability meets the preset stability rule of the forklift posture stability, an open-loop control condition of the forklift posture is generated;

[0124] When the posture stability does not meet the preset stability rule of the forklift posture stability, generating a closed-loop control condition of the forklift;

[0125] The open-loop control condition and the closed-loop control condition are integrated into a two-dimensional ring control strategy.

[0126] If the control process is not closed-loop, that is, only one control instruction is sent and there is no continuous adjustment of the control strategy based on feedback, it can usually be called an "open-loop control process."

[0127] In detail, the stability rules are formulated after comprehensively considering the physical characteristics of the forklift itself (such as vehicle structure, mass distribution, etc.), design parameters (such as rated load, maximum lifting height, vehicle size, etc.) and actual operation safety requirements. It clearly defines the various conditions under which the vehicle is in a stable posture, covering the parameter ranges of multiple aspects of the vehicle under different working conditions, such as the driving speed limit range under different load conditions, the corresponding allowable lifting height range, the maximum steering angle and angular velocity limit during normal driving, and the reasonable deceleration range during conventional braking. When the vehicle posture stability is judged to meet the above stability rules through sensor monitoring and related calculations, it means that the vehicle is currently in a stable operating state. At this time, an open-loop control condition is generated. The open-loop control condition refers to the link where the vehicle is in a stable state, just like the outer stable area of ​​the ring, and each operating link is operated normally according to the established rules, and less reliance is placed on real-time feedback for adjustment.

[0128] Specifically, when the actual posture stability of the vehicle exceeds the range specified by the previously set stability rules, it means that the vehicle posture is abnormal and may be developing towards critical instability or already in an unstable state. For example, the center of gravity of the cargo changes unreasonably during the operation (such as the cargo sliding on the loading fork causing the center of gravity to shift). Therefore, in order to correct the vehicle posture as soon as possible and restore it to a stable state, it is necessary to generate a closed-loop control condition. The closed-loop control emphasizes the continuous adjustment of the control strategy through real-time feedback to form a detection-judgment-adjustment-re-detection cycle control process. The closed-loop control condition is when the vehicle posture deviates from the stable state and enters a critical or unstable state, which is equivalent to the area inside the ring. The control strategy is continuously adjusted through real-time feedback to guide the vehicle posture to return to the stable area. The entire control process forms a cyclical ring structure, that is, starting from a stable state, if an unstable situation occurs, it is restored to stability through closed-loop control, and then it can continue to operate according to the open-loop control conditions in a stable state. In this way, the forklift posture is stable.

[0129] Furthermore, the loop structure formed by the two-dimensional ring control strategy makes the vehicle posture adjustment a sustainable process. Whether it is the different stages of a single operation task or in long-term multiple operations, the posture can be continuously and effectively adjusted and controlled, always maintaining a stable posture state, minimizing safety accidents caused by posture problems and improving the safety and reliability of vehicle operations.

[0130] S6. Adjust the posture stability of the forklift according to the two-dimensional ring control strategy to obtain a stable posture of the forklift.

[0131] In the embodiment of the present invention, the stable posture refers to the specific spatial state of the forklift truck under the condition of meeting the optimal posture stability, which reflects that the vehicle's inclination in the lateral direction (the roll angle reflects the left and right inclination), longitudinal direction (the pitch angle reflects the front and rear inclination), the center of gravity position (the position in the vehicle coordinate system calculated based on the pressure sensor data) and the force conditions of each part (the distribution of forces related to vehicle driving, lifting, braking operation and posture angle) and other factors are in a balanced state that meets safety requirements.

[0132] In the embodiment of the present invention, the posture stability of the forklift is adjusted according to the two-dimensional ring control strategy to obtain a stable posture of the forklift, including:

[0133] According to the open-loop control condition in the two-dimensional ring control strategy, the posture stability of the forklift after real-time monitoring and joint adjustment is determined as the optimal posture stability of the forklift;

[0134] determining a stable posture of the forklift according to the optimal posture stability;

[0135] updating the stability control instruction according to the closed-loop control condition in the two-dimensional ring control strategy, and returning to the step of jointly adjusting the forklift posture by the stability control instruction until an open-loop control condition for the forklift posture is generated;

[0136] When an open-loop control condition for the posture of the forklift is generated, the posture stability of the forklift after real-time monitoring and joint adjustment is updated to the posture stability corresponding to the open-loop control condition;

[0137] Return to the step of determining the posture stability of the forklift after real-time monitoring and joint adjustment as the optimal posture stability of the forklift according to the open-loop control conditions in the two-dimensional ring control strategy, and obtain a stable posture of the forklift.

[0138] In detail, by real-time monitoring of the posture stability of the forklift after joint adjustment, it is judged whether the vehicle posture meets the stability rules set by the open-loop control conditions based on the real-time monitoring data. If it does, the posture stability presented by the vehicle at this time is the optimal posture stability under the current working conditions, that is, within the established stability rule framework, the various vehicle systems coordinate and cooperate so that the vehicle posture-related parameters are within a reasonable and safe range, achieving an ideal stable state. The posture stability in this state is recognized as the optimal posture stability, which is a good posture foundation for the vehicle to operate safely and efficiently.

[0139] Specifically, when the vehicle's posture stability exceeds the stability rule range set by the open-loop control conditions due to certain reasons (such as sudden external interference, such as strong winds, sudden road conditions, or driver errors, etc.), that is, when the vehicle's posture shows signs of instability, it is necessary to enable closed-loop control conditions. Closed-loop control conditions emphasize dynamic adjustment of control strategies based on real-time feedback. At this time, the control system will analyze the degree and direction of the current posture deviation from the stable state based on the vehicle posture data monitored in real time by the sensor (such as excessive roll angle, abnormal lateral acceleration, etc.), and then update the previous stability control instructions. The updated stability control instructions readjust the vehicle posture. When the open-loop control conditions for the forklift posture are generated after closed-loop control adjustment, it means that the vehicle posture has returned to a stable state. At this time, the posture stability of the forklift after real-time monitoring and joint adjustment must be updated to the posture stability corresponding to the open-loop control conditions.

[0140] The embodiments of the present invention filter the collected sensor data to remove data noise and calibration deviation, thereby improving data accuracy and reliability; calculate demarcation parameters and separation boundary areas, quantify the boundary of posture stability, and clearly divide different posture state intervals to facilitate targeted control strategy formulation; generate joint control strategies and control instructions, coordinate multi-link control requirements, adapt to changes in different working conditions, and ensure the coordination of various operating links; multiple systems collaboratively optimize vehicle posture, respond to posture changes in real time, and keep the vehicle in a relatively stable state during operation; adjust the two-dimensional ring control strategy to obtain a stable posture, continuously ensure safe and stable operation of the vehicle, ensure the stability of the forklift posture from multiple aspects, and improve operation safety and efficiency. Therefore, the intelligent control method and system for the forklift posture stability proposed in the present invention can solve the problem of low efficiency when controlling the forklift posture stability.

[0141] like Figure 2 , which is a functional module diagram of an intelligent control system for forklift posture stability provided by an embodiment of the present invention.

[0142] The intelligent control system 100 for the posture stability of a forklift truck of the present invention can be installed in an electronic device. According to the functions to be implemented, the intelligent control system 100 for the posture stability of a forklift truck can include a data filtering module 101, an actual posture calculation module 102, a boundary parameter calculation module 103, a stability control instruction generation module 104, a two-dimensional ring control strategy generation module 105 and a posture stability adjustment module 106. The module of the present invention can also be referred to as a unit, which refers to a series of computer program segments that can be executed by a processor of an electronic device and can complete fixed functions, which are stored in the memory of the electronic device.

[0143] In this embodiment, the functions of each module / unit are as follows:

[0144] The data filtering module 101 is used to collect raw sensor data of the forklift and perform filtering on the raw sensor data;

[0145] The actual posture calculation module 102 is used to calculate the actual posture of the forklift truck using the pre-built vehicle posture model and the filtered raw sensor data;

[0146] The demarcation parameter calculation module 103 is used to calculate the demarcation parameter of the forklift according to the actual posture, and separate the stability boundary of the forklift posture by the demarcation parameter to obtain the separation boundary area;

[0147] The stability control instruction generating module 104 is used to generate a posture stability joint control strategy of the forklift according to the separation boundary area, and generate a stability control instruction of the forklift according to the posture stability joint control strategy;

[0148] The two-dimensional loop control strategy generating module 105 is used to jointly adjust the posture of the forklift through the stability control instruction, and monitor the posture stability of the forklift after the joint adjustment in real time, and generate a two-dimensional loop control strategy for the posture of the forklift according to the posture stability;

[0149] The posture stability adjustment module 106 is used to adjust the posture stability of the forklift according to the two-dimensional ring control strategy to obtain a stable posture of the forklift.

[0150] In the several embodiments provided by the present invention, it should be understood that the disclosed systems and methods can be implemented in other ways. For example, the system embodiments described above are only illustrative, for example, the division of the modules is only a logical function division, and there may be other division methods in actual implementation.

[0151] Therefore, no matter from which point of view, the embodiments should be regarded as illustrative and non-restrictive, and the scope of the present invention is not limited only according to the above description, and it is intended that all changes within the meaning and scope of equivalent elements within the scope of protection are included in the present invention.

[0152] The embodiments of the present application can acquire and process relevant data based on artificial intelligence technology. Among them, artificial intelligence (AI) is the theory, method, technology and application system that uses digital computers or machines controlled by digital computers to simulate, extend and expand human intelligence, perceive the environment, acquire knowledge and use knowledge to obtain the best results.

[0153] In addition, it is obvious that the word "comprising" does not exclude other units or steps, and the singular does not exclude the plural. The multiple units or systems stated in the system embodiment can also be implemented by one unit or system through software or hardware. The words first, second, etc. are used to indicate names, and do not indicate any specific order.

[0154] Finally, it should be noted that the above embodiments are only used to illustrate the technical solution of the present invention rather than to limit it. Although the present invention has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that the technical solution of the present invention can be modified or replaced by equivalents without departing from the spirit and scope of the technical solution of the present invention.

Claims

1. An intelligent control method for forklift posture stability, characterized in that: The method comprises: Collecting raw sensor data of the forklift, and filtering the raw sensor data; The actual posture of the forklift is calculated using the pre-built vehicle posture model and the filtered raw sensor data; Calculating a boundary parameter of the forklift according to the actual posture, separating the stability boundary of the forklift posture by the boundary parameter to obtain a separation boundary area; generating a posture stability joint control strategy for the forklift according to the separation boundary area, and generating a stability control instruction for the forklift according to the posture stability joint control strategy; The forklift posture is jointly adjusted by the stability control instruction, including: determining the actual posture parameter vector of the forklift according to the real-time posture of the forklift; determining the control parameter according to the stability control instruction; generating a joint adjustment function according to the actual posture parameter vector and a preset posture state variable: Wherein, u is the value of the joint adjustment function, u1(θ, p1) is the joint adjustment function corresponding to the stable state p1 under the actual posture parameter vector θ, u2(θ, p2) is the joint adjustment function corresponding to the critical state p2 under the actual posture parameter vector θ, u3(θ, p3) is the joint adjustment function corresponding to the dangerous state p3 under the actual posture parameter vector θ, and S is the posture state variable; The forklift truck posture is jointly adjusted by using the joint adjustment function, and the posture stability of the forklift truck after the joint adjustment is monitored in real time, and a two-dimensional ring control strategy of the forklift truck posture is generated according to the posture stability; The posture stability of the forklift is adjusted according to the two-dimensional ring control strategy to obtain a stable posture of the forklift.

2. The intelligent control method for forklift posture stability according to claim 1, characterized in that: The filtering process of the raw data of the sensor includes: Obtaining the initial state value, initial covariance matrix and initial state transfer matrix of the forklift, and generating a measurement matrix according to the raw data of the sensor; Calculate the target state value and the target covariance matrix at the target time through the initial state transfer matrix and the initial covariance matrix; The gain coefficient is calculated according to the real-time measurement value in the measurement matrix and the target covariance matrix, the target state value is fused with the real-time measurement value according to the gain coefficient to obtain the optimal state value, and the raw data of the sensor after filtering is determined according to the optimal state value.

3. The intelligent control method for forklift posture stability according to claim 1, characterized in that: The method of calculating the actual posture of the forklift truck using the pre-built vehicle posture model and the filtered raw sensor data includes: Determine the angle data, pressure data and acceleration data of the forklift according to the raw data of the sensor after filtering; Generate a force balance equation and a force-moment balance equation according to the angle data, the pressure data and the acceleration data using a pre-constructed vehicle posture model; The posture equation of the forklift is constructed according to the force balance equation and the force-moment balance equation, wherein the posture equation is: Among them, μ r is the rolling friction coefficient, m v is the vehicle's own mass, m g is the mass of the cargo, g is the acceleration of gravity, θ1 is the pitch angle, θ2 is the roll angle, sin is the sine function, cos is the cosine function, a ′ x is the longitudinal acceleration, a ′ y is the lateral acceleration, (x g ,y g ,z g ) is the coordinate of the center of gravity of the forklift, F ′ 1 is the pressure measurement value of the first wheel, F ′ 2 is the pressure measurement value of the second wheel, F ′ 3 is the pressure measurement value of the third wheel, F ′ 4 is the pressure measurement value of the fourth wheel, F t is the traction force of the forklift, L is the vehicle length of the forklift, and W is the vehicle width of the forklift; Calculating the center of gravity coordinates of the forklift truck using the posture equation, and determining the degree and direction of inclination of the forklift truck according to the center of gravity coordinates; The actual posture of the forklift is determined according to the tilt degree and the tilt direction.

4. The intelligent control method for forklift posture stability according to claim 1, characterized in that: The calculating of the boundary parameters of the forklift according to the actual posture comprises: Extracting static vehicle attributes and dynamic vehicle attributes corresponding to the actual posture; The demarcation value of the forklift truck is calculated according to the static vehicle attribute and the dynamic vehicle attribute, wherein the demarcation value calculation formula is: Among them, R1 is the first dividing value, R2 is the second dividing value, and m s is the frame mass of the forklift, L is the vehicle length of the forklift, g is the acceleration of gravity, h1 is the height of the center of mass of the forklift, is the frame tilt angle, a ′ y is the lateral acceleration, h x is the vertical distance between the forklift's center of mass and the steering axle's articulation axis, m v is the vehicle's own mass, b is the horizontal distance from the center of mass to the rear axle, B1 is the front wheel track, and B2 is the rear wheel track; The first demarcation value and the second demarcation value are determined as demarcation parameters of the forklift truck.

5. The intelligent control method for forklift posture stability according to claim 1, characterized in that: The separation of the stability boundaries of the forklift posture by the boundary parameters to obtain the separation boundary area includes: When the boundary parameter meets the preset first target boundary range, dividing the stable domain boundary line according to the boundary parameter, and generating the stable domain boundary area according to the stable domain boundary line; When the boundary parameter meets the preset second target boundary range, dividing a critical boundary line according to the boundary parameter, and generating a critical domain boundary area according to the critical boundary line; When the boundary parameter meets the preset third target boundary range, dividing the danger zone boundary line according to the boundary parameter, and generating the danger zone boundary area according to the danger zone boundary line; The stable domain boundary area, the critical domain boundary area and the dangerous domain boundary area are merged into a separation boundary area.

6. The intelligent control method for forklift posture stability according to claim 1, characterized in that: The generating of the posture stability joint control strategy of the forklift according to the separation boundary area includes: Determining driving data, lifting data and braking data of the forklift according to each boundary area in the separation boundary area; generating a driving control strategy for each boundary area according to the driving data, generating a lifting control strategy for each boundary area according to the lifting data, and generating a braking control strategy for each boundary area according to the braking data; A posture stability joint control strategy of the forklift in each boundary area is determined according to the driving control strategy, the lifting control strategy and the braking control strategy.

7. The intelligent control method for forklift posture stability according to claim 6, characterized in that: The step of generating a stability control instruction for a forklift according to the posture stability joint control strategy comprises: Determine a driving speed command and a steering command according to the driving control strategy in the posture stability combined control strategy, determine a lifting speed command and a center of gravity monitoring command according to the lifting control strategy, and determine a braking mode command according to the braking control strategy; Generate a driving control instruction according to the driving speed instruction and the steering instruction, generate a lifting control instruction according to the lifting speed instruction and the center of gravity monitoring instruction, and generate a braking control instruction according to the braking mode instruction; The travel control instruction, the lifting control instruction and the braking control instruction are packaged into a stability control instruction of the forklift.

8. The intelligent control method for forklift posture stability according to claim 1, characterized in that: The two-dimensional circular control strategy for generating a forklift posture according to the posture stability includes: When the posture stability meets the preset stability rule of the forklift posture stability, an open-loop control condition of the forklift posture is generated; When the posture stability does not meet the preset stability rule of the forklift posture stability, generating a closed-loop control condition of the forklift; The open-loop control condition and the closed-loop control condition are integrated into a two-dimensional ring control strategy.

9. The intelligent control method for forklift posture stability according to claim 7, characterized in that: The step of adjusting the posture stability of the forklift according to the two-dimensional ring control strategy to obtain a stable posture of the forklift includes: According to the open-loop control condition in the two-dimensional ring control strategy, the posture stability of the forklift after real-time monitoring and joint adjustment is determined as the optimal posture stability of the forklift; determining a stable posture of the forklift according to the optimal posture stability; updating the stability control instruction according to the closed-loop control condition in the two-dimensional ring control strategy, and returning to the step of jointly adjusting the forklift posture by the stability control instruction until an open-loop control condition for the forklift posture is generated; When an open-loop control condition for the posture of the forklift is generated, the posture stability of the forklift after real-time monitoring and joint adjustment is updated to the posture stability corresponding to the open-loop control condition; Return to the step of determining the posture stability of the forklift after real-time monitoring and joint adjustment as the optimal posture stability of the forklift according to the open-loop control conditions in the two-dimensional ring control strategy, and obtain a stable posture of the forklift.

10. An intelligent control system for forklift posture stability, characterized in that: The system comprises: A data filtering module, used to collect raw sensor data of the forklift and perform filtering on the raw sensor data; The actual posture calculation module is used to calculate the actual posture of the forklift truck using the pre-built vehicle posture model and the filtered raw sensor data; A boundary parameter calculation module, used for calculating the boundary parameters of the forklift according to the actual posture, and separating the stable boundaries of the forklift posture by the boundary parameters to obtain a separation boundary area; A stability control instruction generating module, used for generating a posture stability joint control strategy of the forklift according to the separation boundary area, and generating a stability control instruction of the forklift according to the posture stability joint control strategy; A two-dimensional ring control strategy generation module is used to jointly adjust the posture of the forklift truck through the stability control instruction, including: determining the actual posture parameter vector of the forklift truck according to the real-time posture of the forklift truck; determining the control parameter according to the stability control instruction; generating a joint adjustment function according to the actual posture parameter vector and a preset posture state variable: Wherein, u is the value of the joint adjustment function, u1(θ, p1) is the joint adjustment function corresponding to the stable state p1 under the actual posture parameter vector θ, u2(θ, p2) is the joint adjustment function corresponding to the critical state p2 under the actual posture parameter vector θ, u3(θ, p3) is the joint adjustment function corresponding to the dangerous state p3 under the actual posture parameter vector θ, and S is the posture state variable; The forklift truck posture is jointly adjusted by using the joint adjustment function, and the posture stability of the forklift truck after the joint adjustment is monitored in real time, and a two-dimensional ring control strategy of the forklift truck posture is generated according to the posture stability; The posture stability adjustment module is used to adjust the posture stability of the forklift according to the two-dimensional ring control strategy to obtain a stable posture of the forklift.

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