Forklift drive-by-wire drum brake system control method and device based on robust H infinity

Abstract

A robust H-infinity control strategy suitable for a forklift drive-by-wire drum brake system specifically comprises the following implementation steps that (1) mechanism analysis is conducted on a mechanical structure and dynamic characteristics of the forklift drive-by-wire drum brake system, and then a dynamic model of the forklift drive-by-wire drum brake system is constructed; 2) designing an adaptive robust H-infinity control gain K according to the model established in the step 1, so as to ensure that the system state can quickly tend to be stable; (3) based on the control gain K designed in the step (2), a robust H-infinity control algorithm for the drive-by-wire drum brake system of the forklift is designed; and 4) based on the Lyapunov stability theory, proving that the control algorithm designed in the step 3 can enable the system state to be stably converged, and carrying out numerical simulation in an MATLAB / Simulink environment so as to verify the actual control effect of the control algorithm in the braking system. And the control precision and robustness of the drive-by-wire drum brake system of the forklift can be obviously improved.

Description

Technical Field

[0001] This invention relates to the technical field of industrial vehicle brake-by-wire control. Specifically, it proposes a control method and corresponding device for a forklift brake-by-wire drum brake system based on a robust H∞ strategy. This solution aims to improve the control accuracy, response speed, and robustness of the forklift brake-by-wire drum brake system in complex and changing operating conditions. Background Art

[0002] With the development of intelligent and unmanned logistics systems, forklifts, as important industrial transportation equipment, face the challenge of ensuring the accuracy and robustness of their control systems, which have become critical factors affecting operational efficiency and safety. Traditional hydraulic or mechanical braking systems have limitations in terms of control accuracy, response speed, and system integration, making them unable to meet the demands of modern intelligent warehousing and handling environments for high-performance, safe, and reliable braking systems. Consequently, brake-by-wire (BBW) technology, based on electronically controlled signal transmission, has been researched and applied. In particular, in the field of new energy forklifts, the use of wire-controlled drum brake systems effectively simplifies the structure, improves control accuracy, and enables the integration of multiple braking strategies, becoming a key direction in the technological evolution of forklift brake systems. However, in practical applications, forklifts face complex and variable operating conditions, such as load fluctuations, varying road friction coefficients, inconsistent brake drum clearance, and unstable coupling between the motor and mechanical brake. These factors can lead to uncertainty in the system dynamics model. Furthermore, brake-by-wire systems inherently suffer from actuator hysteresis, nonlinear friction characteristics, and sensor noise, making the control system highly susceptible to external disturbances, leading to performance degradation and even safety hazards.

[0003] To address these challenges, the accuracy and robustness of control strategies have become key indicators in system design. Among numerous control theories, robust H∞ control has become a widely adopted high-performance control strategy in industry due to its superior performance in addressing system uncertainty and external disturbance rejection. Robust H∞ control is essentially an optimization method. Its core concept is to transform the system's disturbance rejection performance into an H∞ norm optimization problem, thereby minimizing the impact of external disturbances or model uncertainty on the system. Compared with traditional PID control or LQR control, H∞ control can maintain system stability and performance constraints even when the system model contains structural uncertainties or parameter perturbations. It is particularly suitable for control scenarios with complex conditions such as time delay, nonlinearity, and strong coupling. In forklift drive-by-wire drum brake systems, factors such as friction coefficient variations, motor brake attenuation, load disturbances, and electronic control signal transmission delays directly affect the stability and accuracy of braking force output. By introducing a robust H∞ controller, the system can maintain accurate control of braking behavior despite modeling errors and environmental disturbances, improving the braking quality and safety of the vehicle.

[0004] Furthermore, robust H∞ control exhibits excellent frequency-domain performance tuning capabilities. It can design weighted functions and weight performance based on the system's sensitivity to high-frequency or low-frequency disturbances, thereby achieving optimal interference suppression across the system's overall frequency band. For forklift drum brake systems, low-frequency disturbances are often associated with factors such as load inertia fluctuations and brake line response delays, while high-frequency disturbances are often linked to signal noise, friction vibration, and other issues. Robust H∞ control, through frequency-domain design techniques, can address disturbances of varying frequencies during the system design phase. Furthermore, robust H∞ control can be effectively integrated with fault detection and fault-tolerant control to achieve fault-tolerant control in the presence of system faults. For example, in the event of performance degradation or failure of the brake actuator, the H∞ control method ensures that the system still meets the desired braking distance and response speed by adjusting the control gain and feedback structure in real time, thus ensuring the safe operation of new energy forklifts.

[0005] In summary, the robust H∞-based control method for a forklift brake-by-wire drum brake system can effectively enhance the system's adaptability to model uncertainty and external disturbances, significantly improving the forklift's braking stability and safety in complex operating environments. This control method and device not only boast high-precision and robust control performance but also lay a solid technical foundation for the development of intelligent and adaptive brake-by-wire systems, possessing broad engineering application prospects and promotional value. Summary of the Invention

[0006] To address the issues of slow response, low control accuracy, and weak robustness that current forklift-by-wire drum brake systems face under complex operating conditions, this paper proposes a robust H∞-based forklift-by-wire drum brake method and device. Compared to traditional control technologies, this paper introduces a robust H∞ control algorithm to address system uncertainties and external disturbances, maintaining excellent control performance under multiple operating conditions, thereby further ensuring the operational safety and handling efficiency of new energy forklifts.

[0007] To solve the above technical problems, the first aspect of the present invention relates to a robust H∞ control method for a forklift wire-controlled drum brake system, which specifically comprises the following steps:

[0008] Step 1: Analyze the mechanical structure and dynamic characteristics of the forklift's wire-controlled drum brake system, and then construct its dynamic model;

[0009] Step 2: Based on the model established in step 1, design an adaptive robust H∞ control gain K to ensure that the system state can quickly stabilize;

[0010] Step 3: Based on the control gain K designed in step 2, design a robust H∞ control algorithm for the forklift drive-by-wire drum brake system;

[0011] Step 4: Based on Lyapunov stability theory, prove that the control algorithm designed in step 3 can make the system state converge stably, and carry out numerical simulation in the MATLAB / Simulink environment to verify the actual control effect of the control algorithm in the braking system.

[0012] The second technical solution of this invention relates to a robust H∞ control device for forklift brake-by-wire drum brake systems. This device integrates an electronic hydraulic brake (EHB) system, an electronic control unit (ECU), and a data communication module to form a collaborative control platform for high-precision, real-time control of the forklift brake-by-wire system.

[0013] This invention addresses the braking control issues of forklifts in complex operating scenarios and proposes a new control strategy designed to effectively address the lack of robustness of traditional control schemes due to factors such as inaccurate system models, nonlinear characteristics, and external interference. Compared to existing technologies, this solution has the following characteristics: By designing a robust H∞ control algorithm, the stability and anti-interference capabilities of the forklift's wire control brake system in the face of system parameter changes and external disturbances are significantly enhanced. The system can maintain reliable operation under complex and changing operating conditions (such as heavy loads, no loads, or frequent starts and stops), thereby significantly improving the operating efficiency and operational safety of the forklift. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] To more intuitively illustrate the technical solution of the present invention, a brief introduction to the drawings cited in the technical description of the present invention is now provided. It should be noted that the following drawings are only schematic diagrams of some embodiments of the present invention. Those skilled in the art can draw similar diagrams in other forms based on these drawings without inventive effort.

[0015] Figure 1 This is a schematic diagram of the dynamic modeling principle of the forklift wire-controlled drum brake system proposed in the present invention;

[0016] Figure 2 The structure diagram of the simulation program built on the MATLAB / Simulink platform is shown;

[0017] Figure 3 The following is a MATLAB / Simulink simulation result diagram of the master cylinder piston position tracking performance under steady braking conditions;

[0018] Figure 4 The following is the MATLAB / Simulink simulation result of the master cylinder piston position tracking error under steady braking conditions;

[0019] Figure 5 The MATLAB / Simulink simulation results of the servo motor output torque under smooth braking conditions are shown;

[0020] Figure 6 The following is a MATLAB / Simulink simulation result diagram of the master cylinder piston position tracking performance under emergency braking conditions;

[0021] Figure 7 The following is a MATLAB / Simulink simulation result diagram of the master cylinder piston position tracking error under emergency braking conditions;

[0022] Figure 8 The MATLAB / Simulink simulation results of the servo motor output torque under emergency braking conditions are shown;

[0023] Figure 9 4 is an implementation flow chart of the control method of the present invention. DETAILED DESCRIPTION

[0024] The technical solution of the present invention is further described below with reference to the accompanying drawings.

[0025] Example 1

[0026] This embodiment relates to a robust H∞ control method applied to a forklift wire-controlled drum brake system. The specific implementation steps are as follows:

[0027] Step 1: Analyze the mechanical structure and dynamic characteristics of the forklift's wire-controlled drum brake system, and then construct its dynamic model;

[0028] 1. Assume that the actual displacement of the master cylinder piston in the system is x and the actual speed is The acceleration is n represents the gear ratio, λ is the transmission efficiency, R is the gear radius, h is the internal hydraulic pressure of the system, c is the damping coefficient, k is the stiffness coefficient, A sc is the cross-sectional area of ​​the master cylinder piston, T m is the motor output torque. Based on the analysis of the relationship between the various physical quantities within the forklift's wire-controlled drum brake system and combined with Newton's second law, the dynamic equation of the brake system can be derived as follows:

[0029]

[0030] Among them, F r is the rack force, F h is the internal hydraulic pressure of the system, F s is the spring force, F f For friction.

[0031] Based on the mechanical structure and physical principles, it is assumed that the movement of the master cylinder piston does not affect the fluid volume in the system. Therefore, the dynamic relationship of the hydraulic part of the system can be expressed as follows:

[0032]

[0033] in, is defined as the first-order derivative of h with respect to time, Q represents the volume flow of brake fluid inside the system, β e Indicates the bulk modulus of brake fluid.

[0034] The wheel cylinder hydraulic pressure model of the system is given below:

[0035]

[0036] Among them, h sc Indicates wheel cylinder hydraulic pressure. Considering Substituting formula (4) into formula (3) yields:

[0037] (5)

[0038] According to formula (5), the mapping relationship between the master cylinder pressure and the piston position can be obtained as follows:

[0039]

[0040] Where h0 is the initial pressure in the cylinder.

[0041] In practical applications, there is a nonlinear relationship between the master cylinder pressure h and the piston displacement x. This relationship is affected by various factors, including dead zone effects, friction, temperature fluctuations, and brake pad wear. In dynamic modeling, these nonlinear effects can be considered as disturbances in the system. To facilitate modeling and control algorithm design, a second-order polynomial can be used to fit the relationship curve between the master cylinder pressure h and the piston displacement x. This method not only reflects the trend of pressure changes with displacement but also simplifies the construction of subsequent control strategies. The fitted second-order relationship between pressure h and displacement x is expressed as follows:

[0042] h=ηx 2 (7)

[0043] Among them, the parameter η is an important characteristic variable that describes the relationship between the master cylinder pressure h and the piston displacement x. Its physical meaning is closely related to the overall stiffness of the system and the properties of the hydraulic medium.

[0044] The core purpose of the above modeling method is to provide a dynamic model with reasonable accuracy and easy implementation for the control algorithm design of the forklift wire control brake system, rather than pursuing a completely accurate physical characterization of the system.

[0045] Based on the above analysis, the complete dynamic model of the controlled system can be obtained as follows:

[0046]

[0047] Where w is the lumped model parameter uncertainty. According to the mechanical structure and dynamic properties of the forklift wire control brake system, it can be assumed that the lumped perturbation has an upper bound, that is, in, For its upper bound.

[0048] Step 2: Design a robust H∞ control gain K to ensure that the system state can quickly stabilize;

[0049] The original dynamics model of the system expressed in differential equations is as follows:

[0050]

[0051] In the above formula, let u=T m , x1=x, Then it is converted into a state space model as follows:

[0052]

[0053] Since the value of variable x is small in actual working conditions, usually less than 0.08 m, its quadratic term x 2 The impact on the overall result can be approximated to zero, so it is ignored in the modeling / analysis process, resulting in a simplified system state space model as follows:

[0054]

[0055] The above formula is written as a standard state space model as follows:

[0056]

[0057] in,

[0058] The master cylinder piston displacement tracking error is defined as follows:

[0059] e=x1-x r (13)

[0060] Then, the design expected error dynamics is as follows:

[0061]

[0062] Among them, a1 and a2 are the artificially designed error convergence speeds; w eqRepresents all equivalent disturbances in the system, including model uncertainty, external disturbances, modeling errors, and nonlinear residuals.

[0063] Define the augmented state as follows:

[0064]

[0065] Based on this, the final expression of error dynamics is as follows:

[0066]

[0067] in, u a It is the auxiliary control quantity to be designed.

[0068] The designed H∞ performance indicators are as follows:

[0069]

[0070] Among them, Q is an artificially set weighting matrix, and ξ is the disturbance suppression performance index.

[0071] Then, the control gain K of the robust H∞ control algorithm is designed as follows:

[0072]

[0073] Where P is a symmetric positive definite matrix that must satisfy the following Riccati matrix inequality conditions:

[0074]

[0075] Step 3: Based on the control gain K, a robust H∞ control algorithm is designed for the forklift drive-by-wire drum brake system.

[0076] According to the obtained adaptive control gain K, the robust H∞ control algorithm is designed as follows:

[0077]

[0078] Step 4: Based on Lyapunov stability theory, prove that the designed control algorithm can make the system state converge stably. Simulate in MATLAB / Simulink environment to verify the actual control effect of the control algorithm in the braking system.

[0079] The Lyapunov function is defined as follows:

[0080] V(t)=z T (t)Pz(t) (21)

[0081] Taking the first-order derivative of the Lyapunov function yields:

[0082]

[0083] After substituting the control algorithm (20) into the above formula, we can get:

[0084]

[0085] Based on the following standard quadratic inequality:

[0086]

[0087] Where ∈ is any positive number. For the convenience of calculation, we take ∈=ξ 2 , we can get:

[0088]

[0089] After further sorting, we get:

[0090]

[0091] The design goal of robust H∞ control is to make the z-related term of this inequality non-positive. In order to suppress the system state energy as much as possible, the natural energy change of the system can be Set to -Q, and because Formula (26) can be simplified as:

[0092]

[0093] Integrating both sides of formula (27) yields:

[0094]

[0095] Therefore, the system satisfies:

[0096]

[0097] This shows that the energy magnification factor (H∞ norm) of the system state to the equivalent disturbance satisfies ||G|| ∞ <ξ. Therefore, the robust H∞ control system can ensure that the closed-loop feedback tracking error is bounded under energy-bounded disturbances and has specified stability.

[0098] The dynamic model parameters and values ​​of the forklift wire-controlled drum brake system are given as follows:

[0099]

[0100]

[0101] In the simulation, two verification conditions are designed. The first is smooth braking, and the expected master cylinder piston position xr The expression is as follows:

[0102]

[0103] The second is the emergency braking condition, where the expected master cylinder piston position x of the forklift's wire-controlled brake system is r is its extreme position, that is, x r =0.06m.

[0104] The simulation program built on the MATLAB / Simulink software platform is as follows Figure 2 As shown in the simulation results, Figures 3 to 8 shown.

[0105] Simulation results demonstrate that the designed robust H∞ control algorithm can achieve stable tracking of the master cylinder piston relative to the reference position, demonstrating good control stability and robustness. This further demonstrates that the robust H∞ control algorithm has excellent tracking performance for different types of master cylinder piston target trajectories, effectively verifying the applicability and reliability of this control method in forklift brake-by-wire systems.

[0106] Example 2

[0107] This embodiment relates to a robust H∞ device for a forklift drive-by-wire drum brake system. It implements precise closed-loop tracking of the desired master cylinder piston position by using a pedal displacement sensor, a data acquisition module, a servo motor encoder, a CAN data bus, a host computer with a built-in robust H∞ control algorithm, an electronic control unit (ECU), a master cylinder servo motor, brake fluid lines, an in-cylinder pressure sensor, and a data communication unit. The specific implementation steps are as follows:

[0108] Step 1: Receive a braking demand input signal from a forklift;

[0109] When the driver steps on the brake pedal, the pedal displacement sensor converts its displacement change into a corresponding electrical signal output.

[0110] Step 2: Calculate the target braking response signal based on the input information;

[0111] After receiving the electrical signal from the pedal displacement sensor, the host computer calculates the expected piston displacement value based on the mapping rule between the forklift pedal stroke and the target master cylinder piston displacement, and uses it as the reference signal for the robust H∞ control system. The host computer runs the robust H∞ control algorithm and adjusts the control parameters according to the current braking demand and the real-time status of the system (i.e. the actual position x of the piston in the master cylinder and the speed x). ), generating a control signal, i.e., the target output torque of the servo motor. The actual displacement x of the master cylinder piston is indirectly calculated by measuring the angular displacement signal obtained from the servo motor encoder and based on the mapping relationship between angular displacement and piston displacement.

[0112] Step 3: Transmit the calculated control instructions to the execution unit;

[0113] The host computer sends relevant signals to the electronic control unit (ECU) through the CAN bus, including the desired position signal of the master cylinder piston and the torque command signal for controlling the servo motor.

[0114] Step 4: Drive the actuator to complete the braking operation;

[0115] After receiving the control instructions transmitted by the host computer, the electronic control unit (ECU) starts the servo motor inside the EHB system, and the servo motor drives the master cylinder piston through the internal reduction gear transmission mechanism to achieve feed motion.

[0116] Step 5: Generate corresponding braking force;

[0117] The feed movement of the master cylinder piston compresses the brake fluid in the cylinder, allowing it to be delivered to the brake line and further act on the wheel cylinder, thereby generating the braking force required to brake the forklift wheels.

[0118] Step 6: Adjust the control accuracy through closed-loop feedback mechanism;

[0119] The in-cylinder pressure sensor and the servo motor angular displacement sensor jointly monitor the system status in real time, primarily for obtaining the current position of the master cylinder piston. The electronic control unit (ECU) transmits the signals collected by these sensors to the host computer via the CAN bus. Based on this feedback information and in conjunction with the robust H∞ control algorithm, the data communication module adjusts the control variable (i.e., the servo motor output torque) in real time. The updated control signal is then retransmitted to the slave ECU, dynamically correcting the braking process. This creates a closed-loop feedback control structure, ensuring that the master cylinder piston accurately follows the set target position and maintains the required hydraulic pressure within the master cylinder, effectively meeting the forklift's braking requirements.

[0120] The above content is only an embodiment of the present invention, which is intended to illustrate the technical solution of the present invention and does not constitute a limitation on its scope of application. For those skilled in the art, various forms of modification, replacement or optimization can be made without departing from the core ideas and basic principles of the present invention, and equivalent variations of these technical solutions should be included in the scope of protection of the present invention.

Claims

1. A robust H∞ control strategy for a forklift drive-by-wire drum brake system, comprising the following implementation steps: Step 1: Analyze the mechanical structure and dynamic characteristics of the forklift's wire-controlled drum brake system, and then construct its dynamic model; Step 2: Based on the model established in step 1, design an adaptive robust H∞ control gain K to ensure that the system state can quickly stabilize; Step 3: Based on the control gain K designed in step 2, design a robust H∞ control algorithm for the forklift drive-by-wire drum brake system; Step 4: Based on Lyapunov stability theory, prove that the control algorithm designed in step 3 can make the system state converge stably, and carry out numerical simulation in the MATLAB / Simulink environment to verify the actual control effect of the control algorithm in the braking system.

2. The method according to claim 1, wherein Step 1 further includes the following: setting the actual displacement of the master cylinder piston in the system to x and the actual speed to The acceleration is n represents the gear ratio, λ is the transmission efficiency, R is the gear radius, h is the internal hydraulic pressure of the system, c is the damping coefficient, k is the stiffness coefficient, A sc is the cross-sectional area of ​​the master cylinder piston, T m is the motor output torque. Based on the analysis of the relationship between the various physical quantities in the forklift's wire-controlled drum brake system and combined with Newton's second law, the dynamic equation of the brake system can be derived as follows: Among them, F r is the rack force, F h is the internal hydraulic pressure of the system, F s is the spring force, F f is the friction force, Based on the mechanical structure and physical principles, it is assumed that the movement of the master cylinder piston does not affect the fluid volume in the system. Therefore, the dynamic relationship of the hydraulic part of the system can be expressed as follows: in, is defined as the first derivative of h with respect to time, Q represents the volume flow of brake fluid inside the system, β e represents the bulk modulus of the brake fluid, The wheel cylinder hydraulic pressure model of the system is given below: Among them, h sc Indicates wheel cylinder hydraulic pressure, taking into account Substituting formula (4) into formula (3) yields: According to formula (5), the mapping relationship between the master cylinder pressure and the piston position can be obtained as follows: Where h0 is the initial pressure in the cylinder, In order to simplify the mapping relationship between the master cylinder pressure and the piston position shown in formula (6), a second-order polynomial is used to fit the relationship curve of formula (6). The second-order relationship expression between the master cylinder pressure h and the piston displacement x after fitting is as follows: h=ηx 2 (7) The parameter η is an important characteristic variable that describes the relationship between the master cylinder pressure h and the piston displacement x. Its physical meaning is closely related to the overall stiffness of the system and the properties of the hydraulic medium. Based on the above analysis, the complete dynamic model of the controlled system can be obtained as follows: Where w is the lumped model parameter uncertainty. According to the mechanical structure and dynamic properties of the forklift wire control brake system, it can be assumed that the lumped perturbation has an upper bound, that is, in, For its upper bound.

3. The method according to claim 1, wherein Step 2 specifically includes: The original dynamics model of the system expressed in differential equations is as follows: In the above formula, let u=T m , x1=x, Then it is converted into a state space model as follows: Since the value of variable x is small in actual working conditions, usually less than 0.08 m, its quadratic term x 2 The impact on the overall result can be approximated to zero, so it is ignored in the modeling / analysis process, resulting in a simplified system state space model as follows: The above formula is written as a standard state space model as follows: in, The master cylinder piston displacement tracking error is defined as follows: e=x1-x r (13) Furthermore, the design expected error dynamics is as follows: Among them, a1 and a2 are the artificially designed error convergence speeds; w eq Represents all equivalent disturbances in the system, including model uncertainty, external disturbances, modeling errors, and nonlinear residuals, Define the augmented state as follows: Based on this, the final expression of error dynamics is as follows: in, u a is the auxiliary control quantity to be designed, The designed H∞ performance indicators are as follows: Among them, Q is an artificially set weighting matrix, ξ is the disturbance suppression performance index, Then, the control gain K of the robust H∞ control algorithm is designed as follows: Where P is a symmetric positive definite matrix that must satisfy the following Riccati matrix inequality conditions:

4. The method according to claim 1, wherein Step 3 specifically includes: According to the obtained adaptive control gain K, the robust H∞ control algorithm is designed as follows:

5. The method according to claim 1, wherein Step 4 specifically includes: The Lyapunov function is defined as follows: V(t)=z T (t)Pz(t) (21) Taking the first-order derivative of the Lyapunov function yields: After substituting the control algorithm (20) into the above formula, we can get: Based on the following standard quadratic inequality: Where ∈ is any positive number. For the convenience of calculation, we take ∈=ξ 2 , we can get: After further sorting, we get: The design goal of robust H∞ control is to make the z-related term of this inequality non-positive. In order to suppress the system state energy as much as possible, the natural energy change of the system can be Set to -Q, and because Formula (26) can be simplified as: Integrating both sides of formula (27) yields: Therefore, the system satisfies: This shows that the energy magnification factor (H∞ norm) of the system state to the equivalent disturbance satisfies ||G|| ∞ <ξ.

6. A robust H∞ device for a forklift drive-by-wire drum brake system includes a pedal displacement sensor, a data acquisition module, a servo motor encoder, a CAN data bus, a host computer with a built-in robust H∞ control algorithm, a slave electronic control unit (ECU), a master cylinder servo motor, an internal reduction gear transmission mechanism, brake fluid lines, an in-cylinder pressure sensor, and a data communication unit. This device implements closed-loop feedback control of the desired master cylinder piston position. The specific implementation steps are as follows: Step 1: Receive a braking demand input signal from a forklift driver via a pedal displacement sensor; Step 2: The host computer with built-in robust H∞ control algorithm calculates the target braking response signal based on the input information; Step 3: The upper computer with built-in robust H∞ control algorithm transmits the calculated control instructions to the lower computer of electronic control unit (ECU) through CAN bus; Step 4: The electronic control unit (ECU) drives the servo motor inside the EHB system, which in turn drives the master cylinder piston through the internal reduction gear transmission mechanism to achieve feed motion and complete the braking operation; Step 5: The feed motion compresses the brake fluid in the cylinder, sending it to the brake line and further acting on the wheel cylinder to generate braking force; Step 6: The in-cylinder pressure sensor and the servo motor angular displacement sensor monitor the system status in real time. The electronic control unit (ECU) feeds back the signals collected by these sensors to the host computer through the CAN bus. The host computer adjusts the control quantity in real time through the data communication module and sends the updated control signal to the electronic control unit (ECU) again to dynamically correct the braking execution process and realize closed-loop feedback control.

7. The device according to claim 6, characterized in that Step 1 specifically includes: when the driver steps on the brake pedal, the pedal displacement sensor converts its displacement change into a corresponding electrical signal output.

8. The device according to claim 6, wherein Step 2 specifically includes: after receiving the electrical signal from the pedal displacement sensor, the host computer calculates the expected piston displacement value according to the mapping law between the forklift pedal stroke and the target master cylinder piston displacement, and uses it as the reference signal of the robust H∞ control system. The host computer runs the robust H∞ control algorithm and adjusts the braking force according to the current braking demand and the real-time status of the system (i.e., the actual position x of the piston in the master cylinder and the speed x). ), generates a control signal, i.e., the target output torque of the servo motor. The actual displacement x of the master cylinder piston is obtained by measuring the angular displacement signal obtained by the servo motor encoder and indirectly calculated based on the mapping relationship between the angular displacement and the piston displacement.

9. The device according to claim 6, wherein Step 3 specifically includes: the host computer sends relevant signals to the electronic control unit (ECU) through the CAN bus, including the desired position signal of the master cylinder piston and the torque command signal for controlling the servo motor.

10. The device according to claim 6, wherein Step 4 specifically includes: after receiving the control command transmitted by the host computer, the electronic control unit (ECU) starts the servo motor inside the EHB system, and the servo motor drives the master cylinder piston through the internal reduction gear transmission mechanism to realize the feed motion.

11. The device according to claim 6, wherein Step 5 specifically includes: the feeding movement of the master cylinder piston compresses the brake fluid in the cylinder, so that it is transported to the brake line and further acts on the wheel cylinder, thereby generating the braking force required to brake the forklift wheel.

12. The device according to claim 6, wherein Step 6 specifically includes: the in-cylinder pressure sensor and the servo motor angular displacement sensor jointly monitor the system status in real time, mainly used to obtain the current position of the master cylinder piston. The electronic control unit (ECU) feeds back the signals collected by these sensors to the host computer through the CAN bus. Based on this feedback information, the host computer combines the robust H∞ control algorithm to adjust the control quantity (i.e., the servo motor output torque) in real time through the data communication module, and sends the updated control signal again to the lower computer ECU to dynamically correct the braking execution process, realizing closed-loop feedback control, ensuring that the master cylinder piston can accurately follow the set target position and maintain the required hydraulic pressure inside the master cylinder, thereby effectively meeting the braking needs of the forklift.

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