EMB system clamping force calibration method

Abstract

The application provides an EMB system clamping force calibration method, comprising the following steps: S1: setting the EMB system on a test bench; S2: setting a force sensor and a first full-bridge measurement circuit on the EMB system; S3: controlling the EMB motor to perform a plurality of clamping-unloading cycles, synchronously collecting the clamping force F by using the force sensor and collecting the first strain value ε1 by using the first full-bridge measurement circuit; S4: fitting to obtain a functional relationship between the clamping force F and the first strain value ε1; S5: retaining the first full-bridge measurement circuit and setting the EMB system on a whole vehicle, and calibrating the output clamping force of the EMB system by using the functional relationship and the currently collected first strain value ε1. The application solves the problem that the existing clamping force calibration method is inconvenient for whole vehicle calibration.

Description

Technical Field

[0001] This application relates to the technical field of automotive braking components, and in particular to a method for calibrating the clamping force of an EMB system. Background Technology

[0002] In EMB (Electro-Mechanical Brake) systems, accurate measurement and calibration of clamping force are crucial for the system's performance and safety. EMB system clamping force calibration requires two steps: first on a test bench (clamping force test bench calibration), and then on the entire vehicle (clamping force vehicle calibration). Existing calibration methods rely on force sensors to directly measure the clamping force. However, force sensors are expensive, and their installation and use during vehicle calibration present numerous inconveniences, such as requiring additional installation space and being susceptible to environmental factors. Therefore, existing clamping force calibration methods suffer from the inconvenience of vehicle calibration. Summary of the Invention

[0003] The purpose of this application is to provide a method for calibrating the clamping force of an EMB system, so as to solve the problem that existing clamping force calibration methods are inconvenient for calibrating the clamping force of the whole vehicle.

[0004] This application provides a method for calibrating the clamping force of an EMB system, including:

[0005] S1: Set up the EMB system on the test bench;

[0006] S2: Set up a force sensor and a first full-bridge measurement circuit in the EMB system;

[0007] S3: Control the EMB motor to perform multiple clamping-unloading cycles, simultaneously using a force sensor to collect the clamping force F and using the first full-bridge measurement circuit to collect the first strain value ε1;

[0008] S4: The functional relationship between the clamping force F and the first strain value ε1 is obtained through fitting; and

[0009] S5: Retain the first full-bridge measurement circuit and set the EMB system on the vehicle. Use the aforementioned functional relationship and the currently acquired first strain value ε1 to calibrate the output clamping force of the EMB system.

[0010] Optionally, the first full-bridge measurement circuit includes a first strain gauge, a second strain gauge, a third strain gauge, and a fourth strain gauge. The first strain gauge and the second strain gauge are connected in series to form a first branch, and the third strain gauge and the fourth strain gauge are connected in series to form a second branch. The first branch and the second branch are connected in parallel, and the first strain value ε1 is the voltage between the midpoint of the first branch and the midpoint of the second branch.

[0011] Optionally, the first full-bridge measurement circuit is mounted on the force-deformation sensitive area on one side of the EMB system clamp.

[0012] Optionally, step S2 may further include: mounting a second full-bridge measurement circuit on the force deformation sensitive area on the other side of the EMB system clamp.

[0013] Optionally, step S3 further includes: synchronously acquiring a second strain value ε2 using the second full-bridge measurement circuit, comparing the first strain value ε1 and the second strain value ε2, and if the relative deviation between the first strain value ε1 and the second strain value ε2 is less than or equal to a preset threshold, then the average value of the first strain value ε1 and the second strain value ε2 is taken as the valid first strain value ε1.

[0014] Optionally, step S3 further includes: if the relative deviation between the first strain value ε1 and the second strain value ε2 is greater than a preset threshold, then the first strain value ε1 and the second strain value ε2 are re-acquired.

[0015] Optionally, the second full-bridge measurement circuit includes a fifth strain gauge, a sixth strain gauge, a seventh strain gauge, and an eighth strain gauge. The fifth strain gauge and the sixth strain gauge are connected in series to form a third branch, and the seventh strain gauge and the eighth strain gauge are connected in series to form a fourth branch. The third branch and the fourth branch are connected in parallel, and the second strain value ε2 is the voltage between the midpoint of the third branch and the midpoint of the fourth branch.

[0016] Optionally, the second full-bridge measurement circuit and the first full-bridge measurement circuit are symmetrically arranged in the EMB system clamp.

[0017] Optionally, step S3 further includes: repeating each clamping-unloading cycle multiple times, using the average clamping force during each clamping-unloading cycle as the clamping force F, and using the average strain value collected by the first full-bridge measurement circuit during each clamping-unloading cycle as the first strain value ε1.

[0018] Optionally, step S3 further includes: collecting 10 or more sets of clamping force F and first strain value ε1, and the magnitude of the collected clamping force F must cover the range of all working clamping forces of the EMB system.

[0019] The beneficial effects of this application are as follows: Step S1: Set the EMB system on the test bench. Step S2: Set a force sensor and a first full-bridge measurement circuit in the EMB system. Step S3: Control the EMB motor to perform multiple clamping-unloading cycles, simultaneously using the force sensor to collect the clamping force F and the first strain value ε1 to collect the first strain value ε1. Step S4: Fit the functional relationship between the clamping force F and the first strain value ε1. Step S5: Retain the first full-bridge measurement circuit and set the EMB system on the vehicle, using the functional relationship and the currently collected first strain value ε1 to calibrate the output clamping force of the EMB system. Since a force sensor is no longer needed when calibrating the clamping force on the vehicle, the vehicle-wide calibration of the clamping force is more convenient.

[0020] The above description is only an overview of the technical solution of this application. In order to better understand the technical means of this application and to implement it in accordance with the contents of the specification, the following describes the application in detail with reference to the preferred embodiments and accompanying drawings. Attached Figure Description

[0021] Figure 1 This is a flowchart of an EMB system clamping force calibration method according to one embodiment of this application;

[0022] Figure 2 This is a perspective view of an embodiment of the present application, showing the EMB system, the first full-bridge measurement circuit, and the second full-bridge measurement circuit.

[0023] Figure 3 This is a partial cross-sectional view of an EMB system in one embodiment of this application;

[0024] Figure 4 This is a schematic diagram of the arrangement of the first full-bridge measurement circuit and the second full-bridge measurement circuit in one embodiment of this application;

[0025] Figure 5 This is a circuit diagram of the first full-bridge measurement circuit in one embodiment of this application;

[0026] Figure 6 This is a circuit diagram of the second full-bridge measurement circuit in one embodiment of this application.

[0027] In the attached figures, the following labels are used:

[0028] 100 Force Sensor

[0029] 101 First Full-Bridge Measurement Circuit

[0030] R1 First strain gauge

[0031] R2 Second strain gauge

[0032] R3 Third strain gauge

[0033] R4 Fourth Strain Gauge

[0034] 102 clamp body

[0035] 103 Second Full-Bridge Measurement Circuit

[0036] 104 Friction Plate

[0037] R5 Fifth Strain Gauge

[0038] R6 Sixth Strain Gauge

[0039] R7 Seventh Strain Gauge

[0040] R8, the eighth strain gauge

[0041] Steps for S1-S5 EMB System Clamping Force Calibration Method Detailed Implementation

[0042] The following specific embodiments illustrate the implementation of this application. Those skilled in the art can easily understand other advantages and effects of this application from the content disclosed in this specification.

[0043] It should be noted that, unless otherwise specified, the embodiments and features described in this application can be combined with each other. The present application will now be described in detail with reference to the accompanying drawings and embodiments. To enable those skilled in the art to better understand the solutions of this application, the technical solutions in the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of this application, and not all of them. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort should fall within the scope of protection of this application.

[0044] It should be noted that the terms "first," "second," etc., in the specification, claims, and accompanying drawings of this application are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence. Furthermore, the terms "comprising" and "having," and any variations thereof, are intended to cover a non-exclusive inclusion; for example, a process, method, system, product, or device that includes a series of steps or units is not necessarily limited to those steps or units explicitly listed, but may include other steps or units not explicitly listed or inherent to these processes, methods, products, or devices.

[0045] It should be noted that, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "linking" should be interpreted broadly. For example, they can refer to fixed connections, detachable connections, or integral connections; they can refer to mechanical connections or electrical connections; they can refer to direct connections or indirect connections through an intermediate medium; and they can refer to the internal connection between two components. Those skilled in the art can understand the specific meaning of the above terms in this application based on the specific circumstances.

[0046] Please also refer to Figure 1 and Figure 2 This embodiment provides a method for calibrating the clamping force of an EMB system, including:

[0047] S1: Set up the EMB system on the test bench;

[0048] S2: Set up the force sensor 100 and the first full-bridge measurement circuit 101 in the EMB system;

[0049] S3: Control the EMB motor to perform multiple clamping-unloading cycles, and simultaneously use the force sensor 100 to collect the clamping force F and the first strain value ε1 to collect the first full-bridge measurement circuit 101.

[0050] S4: The functional relationship between the clamping force F and the first strain value ε1 is obtained through fitting; and

[0051] S5: Retain the first full-bridge measurement circuit 101 and install the EMB system on the entire vehicle. Use the functional relationship and the currently acquired first strain value ε1 to calibrate the output clamping force of the EMB system. By implementing steps S1 to S5, the force sensor 100 is no longer needed for vehicle-wide clamping force calibration, making vehicle-wide clamping force calibration more convenient. Simultaneously, eliminating the force sensor 100 required for vehicle-wide clamping force calibration also reduces the procurement, installation, and debugging costs of the force sensor 100.

[0052] Calibration is the process of comparing the output of the device under test with known standard values ​​to determine its measurement error, and then adjusting or compensating for the error to make the output result meet the expected accuracy. EMB system clamping force calibration refers to the process of comparing the acquired clamping force with the output clamping force to determine the error between the acquired clamping force and the output clamping force, and then adjusting or compensating for the error to make the output clamping force meet the expected accuracy. An EMB test bench is a key piece of equipment used to evaluate the performance of electromechanical braking systems (EMB). It can perform EMB dynamic performance testing, EMB environmental adaptability verification, EMB durability and fatigue testing, and functional safety and redundancy verification.

[0053] Please also refer to Figure 2 and Figure 3The clamp body 102 of the EMB system is bolted to the test bench or the vehicle. A force sensor 100 is mounted between the contact points of the caliper and the brake pads. The force sensor 100 is also mounted on the brake disc. Both ends of the force sensor 100 face the friction pads 104 and are located between the two friction pads 104. The force sensor 100 is preferably a piezoresistive force sensor. The force sensor 100 is electrically connected to the host computer.

[0054] like Figure 2 As shown, the full-bridge measurement circuit is a high-precision measurement circuit based on the Wheatstone bridge principle. It uses four resistance strain gauges to form a bridge circuit, converting the resistance change of the strain gauges caused by external forces (clamping in this embodiment) into a voltage output, thereby accurately measuring the measured parameter. The four resistance strain gauges constitute the four arms of the Wheatstone bridge. The power supply is connected to one pair of diagonals (input terminals) of the bridge, and the output voltage is measured from the other diagonal (output terminal). The first full-bridge measurement circuit 101 is electrically connected to the host computer.

[0055] A clamping-unloading cycle consists of one clamping and one unloading cycle. During clamping, the tester depresses the brake pedal, and sensors convert the pedal displacement or pressure signal into an electrical signal, which is transmitted to the Electronic Control Unit (ECU). The ECU controls the EMB system based on the electrical signal, pressing the brake pads against the brake disc to generate clamping force. During unloading, the tester releases the brake pedal, and the ECU receives a release signal, generating an unloading control command to control the EMB system, moving the brake pads away from the brake disc and releasing the clamping force.

[0056] The least squares method is preferred for fitting the data. The preferred linear function relationship between the first strain value ε1 and the clamping force F is: F1 = k × ε1 + b, where k is the slope and b is the intercept. The host computer reads the clamping force F and the first strain value ε1 and performs fitting to calculate k and b. When the EMB system calibrates the clamping force on the vehicle, it does not include the force sensor 100. The output clamping force of the EMB system refers to the normal pressure generated on the brake disc by the motor driven by the electronic control unit, which converts the rotational motion into linear motion through a mechanical transmission mechanism (such as a ball screw, planetary gear, etc.).

[0057] When calibrating the output clamping force of the EMB system on the vehicle, the host computer uses the first strain value ε1 collected by the first full-bridge measurement circuit 101 on the vehicle to calculate F1 using the function relationship: F1=k×ε1+b. Then F1 is the calibration value of the output clamping force of the EMB system on the vehicle.

[0058] Please also refer to Figure 4 and Figure 5Optionally, the first full-bridge measurement circuit 101 includes a first strain gauge R1, a second strain gauge R2, a third strain gauge R3, and a fourth strain gauge R4. The first strain gauge R1 and the second strain gauge R2 are connected in series to form a first branch, and the third strain gauge R3 and the fourth strain gauge R4 are connected in series to form a second branch. The first branch and the second branch are connected in parallel. The first strain value ε1 is the voltage V between the midpoint of the first branch and the midpoint of the second branch. out1 The voltage V between the midpoint of the first branch and the midpoint of the second branch is used. out1 As the first strain value ε1, it can improve the detection sensitivity of the first full-bridge measurement circuit 101.

[0059] Please also refer to Figure 4 and Figure 5 A power supply E1 is provided at the parallel connection point of the first and second branches. The length directions of the first strain gauge R1 and the third strain gauge R3 are parallel to the width direction of the EMB system clamp 102, and the first strain gauge R1 and the third strain gauge R3 are spaced apart. The length directions of the second strain gauge R2 and the fourth strain gauge R4 are parallel to the length direction of the EMB system clamp 102, and the second strain gauge R2 and the fourth strain gauge R4 are spaced apart and parallel to each other.

[0060] like Figure 4 As shown, optionally, the first full-bridge measurement circuit 101 is mounted on the force-deformation sensitive area on one side of the EMB system clamp 102. This configuration allows for more accurate calibration of the EMB system's output clamping force by acquiring the first strain value ε1. Preferably, the first full-bridge measurement circuit 101 is adhered to the force-deformation sensitive area on the left side of the EMB system clamp 102 using epoxy resin or phenolic resin adhesive. The force-deformation sensitive area refers to a specific region in the clamp 102 where the internal stress or deformation distribution changes significantly under the clamping force when the EMB system clamps. For example, the central area of ​​the clamp 102 in the vertical direction is the force-deformation sensitive area.

[0061] like Figure 4 As shown, optionally, step S2 further includes: attaching a second full-bridge measurement circuit 103 to the stress-deformation sensitive area on the other side of the EMB system clamp 102. Using a full-bridge circuit enables automatic temperature compensation, improving the sensitivity of strain value detection. The second full-bridge measurement circuit 103, attached to the stress-deformation sensitive area on the other side of the EMB system clamp 102, can more accurately calibrate the output clamping force of the EMB system through the acquired second strain value ε2. The second full-bridge measurement circuit 103 is electrically connected to the host computer. Preferably, the second full-bridge measurement circuit 103 is adhered to the stress-deformation sensitive area on the right side of the EMB system clamp 102 using epoxy resin or phenolic resin adhesive. When the EMB system is installed on the vehicle, the second full-bridge measurement circuit 103 is also attached to the EMB system.

[0062] Please also refer to Figure 4 and Figure 6 Optionally, step S3 further includes: synchronously acquiring a second strain value ε2 using the second full-bridge measurement circuit 103, comparing the first strain value ε1 and the second strain value ε2, and if the relative deviation between the first strain value ε1 and the second strain value ε2 is less than or equal to a preset threshold, then the average value of the first strain value ε1 and the second strain value ε2 is taken as the valid first strain value ε1. This setting can filter abnormal strain value data, improve the reliability of strain value data, and thus improve the accuracy of clamping force calibration. The relative deviation between the first strain value ε1 and the second strain value ε2 can be calculated by the host computer, and whether the relative deviation between the first strain value ε1 and the second strain value ε2 is greater than the preset threshold can also be calculated and compared by the host computer. The preset threshold is preferably 5%.

[0063] Optionally, step S3 further includes: if the relative deviation between the first strain value ε1 and the second strain value ε2 is greater than a preset threshold, then the first strain value ε1 and the second strain value ε2 are re-acquired.

[0064] Please also refer to Figure 4 and Figure 6 Optionally, the second full-bridge measurement circuit 103 includes a fifth strain gauge R5, a sixth strain gauge R6, a seventh strain gauge R7, and an eighth strain gauge R8. The fifth strain gauge R5 and the sixth strain gauge R6 are connected in series to form a third branch, and the seventh strain gauge R7 and the eighth strain gauge R8 are connected in series to form a fourth branch. The third branch and the fourth branch are connected in parallel. The second strain value ε2 is the voltage V between the midpoint of the third branch and the midpoint of the fourth branch. out2 The voltage V between the midpoint of the third branch and the midpoint of the fourth branch is used. out2 As a second strain value ε2, it can improve the detection sensitivity of the second full-bridge measurement circuit 103.

[0065] Please also refer to Figure 4 and Figure 6 The parallel connection point of the third and fourth branches is equipped with power supply E2. The length direction of the fifth strain gauge R5 and the seventh strain gauge R7 is parallel to the width direction of the EMB system clamp 102, and the fifth strain gauge R5 and the seventh strain gauge R7 are spaced apart. The length direction of the sixth strain gauge R6 and the eighth strain gauge R8 is parallel to the length direction of the EMB system clamp 102, and the sixth strain gauge R6 and the eighth strain gauge R8 are spaced apart and parallel to each other.

[0066] like Figure 4As shown, optionally, the second full-bridge measurement circuit 103 and the first full-bridge measurement circuit 101 are symmetrically arranged on the EMB system clamp 102. This arrangement makes the strain values ​​collected by the two full-bridge measurement circuits closer, and makes the cross-verification of the strain values ​​collected by the two full-bridge measurement circuits more accurate. The plane of symmetry between the second full-bridge measurement circuit 103 and the first full-bridge measurement circuit 101 is the vertical mid-plane of the EMB system clamp 102.

[0067] Optionally, step S3 further includes: repeating each clamping-unloading cycle multiple times, using the average clamping force during each repeated clamping-unloading cycle as the clamping force F, and using the average strain value collected by the first full-bridge measurement circuit 101 during each repeated clamping-unloading cycle as the first strain value ε1. This setting can further filter abnormal clamping force and strain value data. The average clamping force and average strain value can be calculated by the host computer. For example, repeating each clamping-unloading cycle 3 times. For example, repeating clamping and unloading with a 10kN output clamping force 3 times, repeating clamping and unloading with a 20kN output clamping force 3 times, etc. Similarly, using the average strain value collected by the second full-bridge measurement circuit 103 during each repeated clamping-unloading cycle as the second strain value ε2.

[0068] Optionally, step S3 further includes: collecting at least 10 sets of clamping force F and first strain value ε1, and ensuring that the magnitude of the collected clamping force F covers the entire range of working clamping forces of the EMB system. This setting allows the functional relationship to characterize a more comprehensive relationship between strain values ​​and output clamping forces, improving the comprehensiveness of the EMB system's output clamping force calibration. The magnitude of the collected clamping force F must cover the entire range of working clamping forces of the EMB system; that is, the collected clamping force F must include at least the maximum and minimum working clamping forces of the EMB system.

[0069] For example, the number of sets of clamping force F and first strain value ε1 collected is equal to 10 sets, and the intervals between the 10 sets of clamping force F can be equal. For example, if the maximum working clamping force is 63 kN, the minimum working clamping force is 0 kN, and the number of sets is 10, then each interval can be set as: (63-0) / 9=7kN, and the 10 sets of clamping forces F are 0kN, 7 kN, 14 kN...63kN respectively. The number of sets of first strain value ε1 and second strain value ε2 is the same and equal to the number of sets of clamping force F. If each clamping-unloading cycle is repeated N times, where N is a positive integer, and the number of sets of clamping force F and first strain value ε1 collected is M, where M is a positive integer greater than or equal to 10, then the final number of sets of clamping force F and first strain value ε1 is N×M.

[0070] The clamping force calibration method for the EMB system provided in this application has been described in detail above. For those skilled in the art, based on the ideas of the embodiments of this application, there will be changes in the specific implementation methods and application scope. Therefore, the content of this specification should not be construed as a limitation of this application. All equivalent modifications or changes made in accordance with the spirit and technical concept of this application should still be covered by the claims of this application.

Claims

1. A method for calibrating the clamping force of an EMB system, characterized in that, include: S1: Set up the EMB system on the test bench; S2: Set up a force sensor and a first full-bridge measurement circuit in the EMB system; S3: Control the EMB motor to perform multiple clamping-unloading cycles, simultaneously using a force sensor to collect the clamping force F and using the first full-bridge measurement circuit to collect the first strain value ε1; S4: The functional relationship between clamping force F and first strain value ε1 is obtained by fitting; as well as S5: Retain the first full-bridge measurement circuit and set the EMB system on the vehicle. Use the aforementioned functional relationship and the currently acquired first strain value ε1 to calibrate the output clamping force of the EMB system.

2. The EMB system clamping force calibration method according to claim 1, characterized in that, The first full-bridge measurement circuit includes a first strain gauge, a second strain gauge, a third strain gauge, and a fourth strain gauge. The first strain gauge and the second strain gauge are connected in series to form a first branch, and the third strain gauge and the fourth strain gauge are connected in series to form a second branch. The first branch and the second branch are connected in parallel, and the first strain value ε1 is the voltage between the midpoint of the first branch and the midpoint of the second branch.

3. The EMB system clamping force calibration method according to claim 1, characterized in that, The first full-bridge measurement circuit is mounted on the force-deformation sensitive area on one side of the EMB system clamp.

4. The EMB system clamping force calibration method according to claim 3, characterized in that, Step S2 also includes: mounting a second full-bridge measurement circuit on the force deformation sensitive area on the other side of the EMB system clamp.

5. The EMB system clamping force calibration method according to claim 4, characterized in that, Step S3 further includes: synchronously acquiring the second strain value ε2 using the second full-bridge measurement circuit, comparing the first strain value ε1 and the second strain value ε2, and if the relative deviation between the first strain value ε1 and the second strain value ε2 is less than or equal to a preset threshold, then the average value of the first strain value ε1 and the second strain value ε2 is taken as the valid first strain value ε1.

6. The EMB system clamping force calibration method according to claim 5, characterized in that, Step S3 further includes: if the relative deviation between the first strain value ε1 and the second strain value ε2 is greater than a preset threshold, then the first strain value ε1 and the second strain value ε2 are re-acquired.

7. The EMB system clamping force calibration method according to claim 5, characterized in that, The second full-bridge measurement circuit includes a fifth strain gauge, a sixth strain gauge, a seventh strain gauge, and an eighth strain gauge. The fifth strain gauge and the sixth strain gauge are connected in series to form a third branch, and the seventh strain gauge and the eighth strain gauge are connected in series to form a fourth branch. The third branch and the fourth branch are connected in parallel. The second strain value ε2 is the voltage between the midpoint of the third branch and the midpoint of the fourth branch.

8. The EMB system clamping force calibration method according to claim 4, characterized in that, The second full-bridge measurement circuit and the first full-bridge measurement circuit are symmetrically arranged in the EMB system clamp.

9. The EMB system clamping force calibration method according to claim 1, characterized in that, Step S3 further includes: repeating each clamping-unloading cycle multiple times, taking the average clamping force when each clamping-unloading cycle is repeated multiple times as the clamping force F, and taking the average strain value collected by the first full-bridge measurement circuit when each clamping-unloading cycle is repeated multiple times as the first strain value ε1.

10. The EMB system clamping force calibration method according to claim 1, characterized in that, Step S3 also includes: collecting 10 or more sets of clamping force F and first strain value ε1, and the magnitude of the collected clamping force F must cover the range of all working clamping forces of the EMB system.

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