Method, system and device for observing braking force of electromechanical brake device and storage medium

Abstract

The application provides an electromechanical brake device braking force observation method, system, equipment and storage medium, and relates to the field of brake control methods.The electromechanical brake device braking force observation method comprises the following steps: using a current closed-loop control method to make a brake motor output a braking force, to push a mechanical actuator into contact with a brake disc, to gradually increase motor cross-axis current, to measure a brake disc pressure and a lead screw displacement characteristic curve, to use a third-order mathematical model to fit a curve expression, to measure the displacement of the mechanical actuator in a braking state, to obtain real-time braking force, and finally to design a brake gap adjustment method to ensure the reliability of the braking force observation.The application realizes the observation mode of the braking force of the electromechanical brake device, meets the precision requirement of the braking force observation of the electromechanical brake device, reduces the installation cost of the system, and improves the stability of long-time operation of the system.

Description

Technical Field

[0001] This invention relates to the field of braking control methods, specifically to a method, system, equipment, and storage medium for observing the braking force of an electromechanical braking device. Background Technology

[0002] Currently, the most widely used train braking systems worldwide are electro-pneumatic braking systems. While these systems can meet the increased braking force requirements of larger tonnage rail vehicles, they suffer from drawbacks such as low control precision, slow response, and high energy consumption and noise. With the development of rail vehicles, electromechanical braking technology has begun to emerge in train braking system development. Electromechanical braking technology is a braking method that uses a brake motor to directly drive a ball screw, which in turn drives a mechanical actuator to compress a brake disc, generating friction and gradually bringing the train to a stop. It is a new type of braking system that can replace air braking technology. Electromechanical braking systems adopt the control command setting process of air braking and eliminate the need for air or hydraulic switching, truly achieving full electrification of the braking system. Currently, electromechanical braking technology has been widely used in many fields due to its superior performance. In the aviation and rail transportation sectors, electromechanical braking control systems are gradually replacing traditional air and hydraulic braking methods. However, the various technologies of electromechanical braking in the rail transportation sector are not yet mature enough, and there is still a long way to go before it truly enters the market.

[0003] Compared to hydraulic and electro-pneumatic braking, electromechanical braking possesses many unique technological advantages, including high braking force precision, fast response speed, simple structure, and high energy conversion efficiency. However, this control method also has certain drawbacks. For example, to achieve precise braking force control, force sensor signals must be introduced to establish closed-loop control. However, considering that trains will experience hundreds of thousands of braking cycles during their actual operation and throughout their lifespan, the safety and reliability of force sensors are questionable. Therefore, a method needs to be designed to monitor the braking force of the electromechanical braking device in real time, obtain braking force data without force sensors, and establish a closed-loop braking force control system.

[0004] Existing research on braking control methods for electromechanical braking systems mainly focuses on system design. Chinese Patent No. CN111959468A discloses a method for controlling the electromechanical braking force of rail vehicles. This method achieves axle and wheel control of friction braking force under normal braking, hybrid control of electromechanical and electric braking, and closed-loop control of friction braking push-out force / clamping force. It realizes high-precision braking force control, real-time wear detection of brake shoes or brake pads, and wear control of basic braking friction components, facilitating vehicle maintenance. Furthermore, it can adaptively adjust the wheel-rail adhesion coefficient according to the actual wheel-rail adhesion of the vehicle. Chinese Patent No. CN113859200A discloses a method and device for brake-by-wire control of rail vehicles. The method and device provided by this invention centralize the vehicle train-level braking control function into a multi-functional vehicle control unit (MVCU) for unified management, with the MVCU managing and distributing the braking force of the entire vehicle. When using the above two control methods to control the braking force of electromechanical braking devices, a large number of force sensors need to be installed, resulting in high costs, and the system reliability decreases with long-term operation. Summary of the Invention

[0005] (a) Technical problems to be solved

[0006] To address the shortcomings of existing technologies, this invention provides a method, system, equipment, and storage medium for observing the braking force of an electromechanical braking device. This solves the problems of existing control methods requiring the installation of a large number of force sensors, resulting in high costs, and the system reliability decreasing over long periods of operation.

[0007] (II) Technical Solution

[0008] To achieve the above objectives, the present invention provides the following technical solution:

[0009] On one hand, the present invention provides a method for observing the braking force of an electromechanical braking device, comprising:

[0010] The brake motor outputs electromagnetic force using a current closed-loop control method.

[0011] This pushes the mechanical actuator into contact with the brake disc;

[0012] Increase the quadrature-axis current of the brake motor;

[0013] Measure the characteristic curve of brake disc pressure versus lead screw displacement;

[0014] Fit the curve expression using a third-order mathematical model;

[0015] The clearance between the mechanical actuator and the brake disc is adjusted using the clearance adjustment method.

[0016] Preferably, the method of using current closed-loop control to make the brake motor output electromagnetic force specifically includes:

[0017] The current output of the electromechanical braking system controller is used to establish a current closed-loop control method based on the collected current signal and position signal, so that the brake motor outputs electromagnetic force to drive the mechanical actuator to contact the brake disc.

[0018] Preferably, the determination of the characteristic curve of brake disc pressure versus lead screw displacement specifically includes:

[0019] After the mechanical actuator contacts the brake disc, the braking current is gradually increased and repeatedly measured to obtain the characteristic curves of brake disc pressure and screw displacement. A third-order mathematical model is established to describe its braking force hysteresis characteristics. Mathematical tools are used to fit the curves to obtain the expression for brake disc pressure and screw displacement. The braking force of the electromechanical braking device can be observed in real time by measuring the screw displacement.

[0020] Preferably, the expression for the brake disc pressure and the lead screw displacement is as follows:

[0021]

[0022] Among them, F h The values ​​represent the brake disc pressure, A3, A2, A1, and A0 are constants obtained from curve fitting, and x represents the lead screw displacement. gap This indicates the relief gap in the diagram. This is the differential term.

[0023] Preferably, the method of adjusting the gap between the mechanical actuator and the brake disc using the gap adjustment method includes:

[0024] After repeated operation of an electromechanical braking device over a long period of time, the brake disc wears out, and the zero point of the expression for brake disc pressure and screw displacement shifts. A gap adjustment experiment method is designed to adjust the gap by combining the forward and backward operation of the mechanical actuator with logical judgment.

[0025] In another aspect, the present invention provides an electromechanical braking system for the above-mentioned method for observing the braking force of an electromechanical braking device. The system includes a braking system controller, a power drive unit, a brake motor, a mechanical actuator, and a brake disc. The braking system controller is used to receive braking commands and issue control commands to the power drive unit. The power drive unit is used to control the starting, stopping, and speed of the brake motor according to the control commands issued by the braking system controller.

[0026] Preferably, the mechanical actuator includes a ball screw structure.

[0027] In another aspect, the present invention also provides an apparatus characterized in that it includes a processor, a memory, and a computer program stored in the memory and configured to be executed by the processor, wherein the processor executes the computer program to implement the above-described method for observing the braking force of an electromechanical braking device.

[0028] In another aspect, the present invention also provides a computer-readable storage medium, characterized in that the computer-readable storage medium includes a stored computer program, wherein the computer program, when running, controls the device where the computer-readable storage medium is located to execute the above-described method for observing the braking force of an electromechanical braking device.

[0029] (III) Beneficial Effects

[0030] The present invention provides a method, system, equipment, and storage medium for observing braking force in an electromechanical braking device, thereby effectively solving the problems of existing control methods requiring the installation of a large number of force sensors, resulting in high costs and decreased system reliability over long periods of operation. Attached Figure Description

[0031] Figure 1 This is a flowchart of the braking force observation method of the electromechanical braking device of the present invention;

[0032] Figure 2 This is a structural diagram of the electromechanical braking system of the present invention;

[0033] Figure 3 This is a characteristic curve of brake disc pressure and lead screw displacement collected in an embodiment of the present invention;

[0034] Figure 4 This is a diagram showing the data collected in an embodiment of the invention regarding the adjustment of the gap between the brake disc and the mechanical actuator. Detailed Implementation

[0035] The technical solutions in the embodiments of the present invention will now be clearly and completely described with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of them. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort are within the scope of protection of the present invention.

[0036] Example 1

[0037] like Figure 1 As shown, this invention proposes a method for observing the braking force of an electromechanical braking device, which is achieved through the following technical steps:

[0038] The first step is to control the output electromagnetic torque of the brake motor to push the mechanical actuator to contact the brake disc, gradually increasing the braking force, and obtaining the characteristic curve of brake disc pressure and screw displacement and fitting the expression.

[0039] 1) The brake motor outputs electromagnetic force using a current closed-loop control method;

[0040] First, the electromechanical braking system controller outputs braking current. Based on the current signal and position signal collected by the circuit, a current closed-loop control method is established to enable the brake motor to output electromagnetic force, drive the mechanical actuator forward, and finally make contact with the brake disc.

[0041] 2) Obtain the characteristic curves of brake disc pressure and lead screw displacement and fit their expressions;

[0042] After the mechanical actuator contacts the brake disc, the braking current is gradually increased and repeatedly measured to obtain the characteristic curves of brake disc pressure and screw displacement. A third-order mathematical model is established to describe its braking force hysteresis characteristics. Mathematical tools are used to fit the curves to obtain the expression for brake disc pressure and screw displacement. The braking force of the electromechanical braking device can be observed in real time by measuring the screw displacement.

[0043] The second step is to adjust the gap between the mechanical actuator and the brake disc using the gap adjustment method.

[0044] 3) Perform forward and reverse operations on the mechanical actuator.

[0045] After a complete braking process, when the mechanical actuator returns to its initial displacement of 0, the motor rotates in the opposite direction, retracting a sufficient distance if space permits within the vehicle. Then, the brake motor is slowly advanced to eliminate the effects of impact inertia. Once the mechanical actuator and brake disc begin to contact, the motor torque (current) will suddenly change; that is, the ratio of the change in motor torque to the change in motor angle will become significantly larger.

[0046] 4) Calculate the brake disc wear value and adjust the clearance distance accordingly.

[0047] Assuming a threshold value, when the ratio of the change in motor torque to the change in motor angle exceeds this threshold, the mechanical actuator can be considered to have reached a critical contact point in real time. By reversing the preset angle from this critical contact point and adjusting the transmission ratio, the actual retraction distance can be calculated, and this distance is clearly accurate. When the brake disc wears, the clearance distance can be updated using this critical contact point and the aforementioned clearance adjustment method.

[0048] This invention proposes a method for observing the braking force of an electromechanical braking device. It utilizes a current closed-loop control method to enable the brake motor to output braking force, pushing the mechanical actuator into contact with the brake disc. Subsequently, the motor's quadrature-axis current is gradually increased to enhance the braking force. The characteristic curves of brake disc pressure and lead screw displacement are measured, and a third-order mathematical model is used to fit the curve expression. Real-time braking force can be obtained by measuring the displacement of the mechanical actuator under braking conditions. The observation method provided by this invention allows the electromechanical braking device to operate normally without sensors, reducing the cost of the electromechanical braking device.

[0049] The present invention proposes a method for observing the braking force of an electromechanical braking device. After obtaining the third-order expression of the characteristic curve of brake disc pressure and lead screw displacement, and considering the wear of the brake disc after long-term and repeated operation, a corresponding clearance adjustment method is designed to adjust the clearance between the mechanical actuator and the brake disc, ensuring the feasibility of the observation method and improving the reliability of the device operation.

[0050] Example 2

[0051] like Figure 1 As shown, this invention proposes a method for observing the braking force of an electromechanical braking device, comprising:

[0052] 1) The brake motor outputs electromagnetic force using a current closed-loop control method;

[0053] 2) To push the mechanical actuator into contact with the brake disc;

[0054] 3) Increase the quadrature-axis current of the brake motor;

[0055] 4) Measure the characteristic curve of brake disc pressure versus lead screw displacement;

[0056] 5) Fit the curve expression using a third-order mathematical model;

[0057] 6) Adjust the pressure between the mechanical actuator and the brake disc using the clearance adjustment method;

[0058] like Figure 3 As shown in the example of this invention, the characteristic curves of brake disc pressure and lead screw displacement are collected. During the process of brake force establishment and release, the brake disc pressure corresponding to the same lead screw displacement is not consistent, and the zero point shifts. The characteristic curves can be fitted using the following third-order expression:

[0059]

[0060] Among them, F h The values ​​represent the brake disc pressure, A3, A2, A1, and A0 are constants obtained from curve fitting, and x represents the lead screw displacement. gap This indicates the relief gap in the diagram. This is the differential term.

[0061] like Figure 4 As shown in the data collected in this invention example regarding the gap adjustment between the brake disc and the mechanical actuator, the initial gap distance was 1 mm, and the adjustment distance was 0.2 mm. The vertical axis represents the slope of the motor torque change with angle, and the horizontal axis represents displacement. The motor speed was 100 r / min. At the contact point, the ratio of the motor torque change to the motor angle change showed a significant increase and remained at a high value thereafter. This is because at the contact point, the mechanical structure is already in contact with the brake surface, and even a slight displacement can lead to a large change in torque and braking force. The experiment demonstrates that the proposed gap distance adjustment method is feasible and effective.

[0062] Example 3

[0063] like Figure 2 As shown, the present invention also proposes an electromechanical braking system for the braking force observation method of the electromechanical braking device in the above embodiments one and two. The system includes a braking system controller, a power drive unit, a brake motor, a mechanical actuator, and a brake disc. The braking system controller is used to receive braking commands and issue control commands to the power drive unit. The power drive unit is used to control the starting, stopping, and speed of the brake motor according to the control commands issued by the braking system controller.

[0064] Furthermore, the mechanical actuator includes a ball screw structure.

[0065] This invention also proposes a device including a processor, a memory, and a computer program stored in the memory and configured to be executed by the processor. When the processor executes the computer program, it implements the method for observing the braking force of the electromechanical braking device in Embodiments 1 and 2 above.

[0066] This invention also proposes a computer-readable storage medium, which includes a stored computer program, wherein, when the computer program is running, it controls the device where the computer-readable storage medium is located to execute the electromechanical braking force observation method of Embodiment 1 and Embodiment 2 described above.

[0067] It should be noted that, in this document, relational terms such as "first" and "second" are used only to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitations, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes said element.

Claims

1. A method for observing the braking force of an electromechanical braking device, characterized in that, include: The brake motor outputs electromagnetic force using a current closed-loop control method. This pushes the mechanical actuator into contact with the brake disc; Increase the quadrature-axis current of the brake motor; Measure the characteristic curve of brake disc pressure versus lead screw displacement; Fit the curve expression using a third-order mathematical model; The clearance between the mechanical actuator and the brake disc is adjusted using clearance adjustment methods. The measurement of the characteristic curve of brake disc pressure and lead screw displacement specifically includes: After the mechanical actuator contacts the brake disc, the braking current is gradually increased and repeatedly measured to obtain the characteristic curve of brake disc pressure and screw displacement. A third-order mathematical model is established to describe its braking force hysteresis characteristics. Mathematical tools are used to fit the curve to obtain the expression of brake disc pressure and screw displacement. The braking force of the electromechanical braking device can be observed in real time by measuring the screw displacement. The expression for the brake disc pressure and lead screw displacement is as follows: Among them, F h The values ​​represent the brake disc pressure, A3, A2, A1, and A0, which are constants obtained from curve fitting, and x, which represents the lead screw displacement. gap This indicates the relief gap in the diagram. For differential terms; The method of adjusting the gap between the mechanical actuator and the brake disc using the gap adjustment method includes: After repeated operation of an electromechanical braking device over a long period of time, the brake disc wears out, and the zero point of the expression for brake disc pressure and screw displacement shifts. A gap adjustment experiment method is designed to adjust the gap by combining the forward and backward operation of the mechanical actuator with logical judgment.

2. The method for observing the braking force of an electromechanical braking device according to claim 1, characterized in that: The method of using current closed-loop control to make the brake motor output electromagnetic force specifically includes: The current output of the electromechanical braking system controller is used to establish a current closed-loop control method based on the collected current signal and position signal, so that the brake motor outputs electromagnetic force to drive the mechanical actuator to contact the brake disc.

3. An electromechanical braking system for observing the braking force of the electromechanical braking device according to any one of claims 1-2, characterized in that, The system includes a braking system controller, a power drive unit, a brake motor, a mechanical actuator, and a brake disc. The braking system controller is used to receive braking commands and issue control commands to the power drive unit. The power drive unit is used to control the starting, stopping, and speed of the brake motor according to the control commands issued by the braking system controller.

4. The electromechanical braking system according to claim 3, characterized in that: The mechanical actuator includes a ball screw structure.

5. A device, characterized in that, It includes a processor, a memory, and a computer program stored in the memory and configured to be executed by the processor, wherein the processor, when executing the computer program, implements the method for observing the braking force of an electromechanical braking device as described in any one of claims 1-2.

6. A computer-readable storage medium, characterized in that, The computer-readable storage medium includes a stored computer program, wherein, when the computer program is executed, it controls the device containing the computer-readable storage medium to perform the electromechanical braking force observation method as described in any one of claims 1-2.

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