IMU (Inertial Measurement Unit) sensor signal processing method and device and electronic braking module

Abstract

The invention discloses an IMU (Inertial Measurement Unit) sensor signal processing method, an IMU sensor signal processing device and an electronic braking module. An IMU sensor is arranged in an integrated electronic braking module on a vehicle firewall; the method comprises the steps that an initial pose signal output by an IMU sensor is processed based on the state of a brake pedal, and a corrected pose signal is obtained and serves as a vehicle pose signal. The method has the advantages that the initial pose output by the IMU sensor which is arranged on the firewall and integrated in the electronic brake module is processed through the steps of filtering, compensation, conversion and the like, and a more accurate pose signal representing the pose of the vehicle is obtained; according to the processing method, interference of the brake pedal on the sensor due to integration in the electronic control module can be effectively reduced, a basic signal processing scheme is provided for integration of the electronic brake module, and braking development of a braking system is promoted.

Description

Technical Field

[0001] The present invention relates to the field of automobile command technology, and in particular to an IMU sensor signal processing method, device and electronic brake module. Background Art

[0002] In order to realize the vehicle stability control function, the vehicle braking system needs to add an IMU sensor (integrated attitude detection sensor). The IMU sensor is used to obtain the vehicle's posture signal and provide the vehicle with a posture signal for vehicle control.

[0003] In order to better detect the vehicle's posture, the IMU sensor of the conventional vehicle braking system will design a separate IMU module and place it at the center of mass of the vehicle to collect the best vehicle posture signal. As the integration of vehicle braking systems becomes higher and higher, IMU sensors are first integrated into ESC products, such as Figure 1 As shown, the IMU sensor chip is integrated into the ESC module, and the IMU signal is directly transmitted to the ESC controller.

[0004] However, as the integration of vehicle braking systems is further strengthened, all braking-related functions are integrated into the integrated electronic brake module installed on the vehicle firewall (referred to as OneBox in the industry). As a braking-related chip, the IMU sensor is also required to be integrated therein. However, because the integrated electronic brake module installed on the vehicle firewall is connected to the driver through the brake pedal, every time the driver steps on the brake pedal, it will cause an impact on the integrated electronic brake module, which will interfere with the signal output quality of the IMU sensor and easily cause the vehicle body stability control function to fail. Therefore, the current mainstream practice in the industry in the prior art is to continue to use an independent IMU module separate from the integrated electronic brake module, such as Figure 2 As shown, the IMU sensor module is connected to the integrated electronic brake module via CAN. On vehicles equipped with integrated electronic brake modules, the IMU sensor is made into a separate electronic module and installed in other locations of the vehicle, generally at the center of mass. The disadvantage of this method is that a separate electronic module needs to be designed, and the electronic module includes a power chip, a CAN interface chip, an MCU, and an IMU sensor. A separate IMU sensor module needs to be configured in the vehicle assembly and wiring harness layout, which has a high system cost and cannot meet the requirements of integration. Summary of the invention

[0005] The purpose of the present invention is to overcome the shortcomings of the prior art and provide an IMU sensor signal processing method, system and electronic braking module. The output signal of the IMU sensor chip is processed to meet the requirement of integrating the IMU in an integrated electronic braking module. The sensor signal is filtered and other processing is performed to meet the requirements of integration and the output posture signal is more accurate.

[0006] In order to achieve the above-mentioned purpose, the technical solution adopted by the present invention is: a method for processing IMU sensor signals, wherein the IMU sensor is installed in an integrated electronic brake module on a vehicle firewall, and the method comprises: processing an initial posture signal output by the IMU sensor based on the state of the brake pedal to obtain a corrected posture signal as a vehicle posture signal.

[0007] The processing of the initial posture signal output by the IMU sensor based on the state of the brake pedal includes:

[0008] A filtering process step, a compensation process step and a synthesis calculation step;

[0009] The filtering processing step is used to filter the initial posture signal output by the IMU sensor to filter out the interference signal generated by the IMU sensor when the pedal is pressed, and obtain a filtered corrected posture signal;

[0010] The compensation processing step is used to compensate for the interference caused by the displacement of the IMU sensor due to the brake pedal being stepped on, and the compensation correction posture signal is obtained after compensating the filtered correction posture signal;

[0011] Synthesis calculation step: used to convert the posture signal into the posture signal at the center of mass of the vehicle.

[0012] The initial posture signal output by the IMU sensor is processed based on the brake pedal being pressed. When the brake pedal is pressed, the filtering process is performed; otherwise, the synthesis calculation process is performed.

[0013] The filtering process step filters the initial posture signal through a filter, wherein the filter is configured as a variable frequency filter, and the cutoff frequency F of the filter matches the rate at which the brake pedal is depressed.

[0014] The compensation processing step includes: obtaining a compensated posture signal corresponding to the brake pedal position through the pedal position after the brake pedal is pressed, and subtracting the compensation posture signal from the filtered corrected posture signal obtained in the filtering processing step to obtain the compensated corrected posture signal after compensation processing.

[0015] The synthetic calculation step includes converting the posture signal to obtain a posture signal corresponding to the vehicle's center of mass position as the vehicle posture signal.

[0016] A comparison table of filter cutoff frequency and brake pedal depression rate is pre-calibrated and set, and the filter cutoff frequency is obtained by looking up the table according to the brake pedal depression rate.

[0017] The cut-off frequency has a negative correlation with the brake pedal depression rate.

[0018] A processing system for an IMU sensor signal, wherein the IMU sensor is installed in an integrated electronic brake module on a vehicle firewall, the system comprises a filtering processing unit, a compensation processing unit and a synthesis calculation unit, and after the brake pedal is stepped on, the filtering processing unit is configured to filter an initial posture signal output by the IMU sensor to filter out interference signals generated by the IMU sensor when the pedal is stepped on, and obtain a filtered corrected posture signal;

[0019] The compensation processing unit is configured to compensate for the interference caused by the displacement of the IMU sensor due to the brake pedal being stepped on, and the compensation processing unit compensates the filtered corrected posture signal to obtain a compensated corrected posture signal;

[0020] The synthesis calculation unit is configured to convert the posture signal into a posture signal at the vehicle's center of mass position as the vehicle position signal.

[0021] An electronic brake module is integrated with an IMU sensor chip. The electronic brake module is arranged on a vehicle firewall and uses the IMU sensor signal processing method to process an initial posture signal output by the IMU sensor chip to obtain a vehicle posture signal.

[0022] The advantages of the present invention are: the initial posture output by the IMU sensor arranged on the firewall and integrated in the electronic brake module is processed through filtering, compensation, conversion and other steps to obtain a more accurate posture signal representing the vehicle posture. The processing method can effectively solve the interference of the brake pedal to the sensor caused by integration in the electronic control module, provide a basic signal processing solution for the integration of the electronic brake module, and promote the development of the brake system; under the processing method, the IMU sensor chip can be integrated into the ECU of the integrated electronic brake module. The integrated electronic brake module is installed on the vehicle firewall and integrates the brake pedal that the driver can operate. The software algorithm detects the action of the driver stepping on the brake pedal, and filters the interference of the brake pedal action on the output signal of the IMU sensor signal, ensuring that the output signal of the IMU sensor chip collected by the brake system can truly reflect the running posture of the vehicle. Under this method, the IMU sensor chip can be integrated into the integrated electronic brake module. This integration method can reduce the system cost of the vehicle braking system and reduce the number of electronic modules and corresponding wiring harness connectors required for vehicle assembly. To help OEMs reduce the cost of the vehicle's braking system, while reducing the number of components and corresponding management costs required on the vehicle; the IMU sensor chip is integrated into the ECU of the integrated electronic brake module. The integrated electronic brake module is installed on the vehicle firewall and integrates a brake pedal that the driver can operate. The software algorithm detects the driver's action of stepping on the brake pedal and filters out the interference of the brake pedal action on the IMU sensor signal output signal, ensuring that the output signal of the IMU sensor chip collected by the braking system can truly reflect the vehicle's operating posture. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] The following is a brief description of the contents expressed in the drawings of the present invention and the symbols in the drawings:

[0024] Figure 1 This is a schematic diagram of the principle of the IMU sensor setting method 1 of the prior art;

[0025] Figure 2 This is a schematic diagram of the principle of IMU sensor setting method 2 of the prior art;

[0026] Figure 3 The schematic diagram of the integrated electronic brake module with an IMU sensor of the present invention;

[0027] Figure 4 The figure is a flow chart of processing output signals of an IMU sensor integrated in an electronic brake module according to the present invention. DETAILED DESCRIPTION

[0028] The specific implementation of the present invention will be further explained in detail below by describing the optimal embodiment with reference to the accompanying drawings.

[0029] like Figure 1 , 2 The schematic diagram of the prior art IMU sensor not integrated in the electronic brake module is shown. This prior art method cannot meet the requirements of automotive integration, resulting in high costs for wiring harnesses, power supply, etc. Figure 3 The schematic diagram of the present application is that the IMU sensor chip is integrated into the electronic brake module WCBS according to the integration requirements. The IMU sensor chip is integrated into the WCBS, and its output end is connected to the central processing unit of the WCBS to output the posture signal collected by the IMU sensor chip to the central processing unit. This integrated approach can greatly save costs, wiring harnesses, etc., because after being integrated into the WCBS, the power supply of the WCBS can be utilized, and no separate power supply and communication are required. However, since the WCBS integrated electronic brake module is disposed on the vehicle firewall and is connected to the brake pedal, the output posture of the IMU sensor chip will be erroneous when the brake pedal is pressed, causing interference. Therefore, this integrated approach needs to solve the problem of the brake pedal interfering with the IMU output posture signal. In this regard, the present embodiment provides a

[0030] A method for processing an IMU sensor signal, wherein the IMU sensor is installed in an integrated electronic brake module on a vehicle firewall, that is, the IMU sensor chip is integrated in the electronic brake module. The method specifically includes: processing an initial posture signal output by the IMU sensor based on the state of a brake pedal to obtain a corrected posture signal as a vehicle posture signal.

[0031] The processing of the initial posture signal output by the IMU sensor based on the state of the brake pedal includes: a filtering processing step, a compensation processing step and a synthesis calculation step;

[0032] In this embodiment, different processing steps are performed according to the different states of the brake pedal. When the brake pedal is pressed, the initial posture signal output by the IMU is successively subjected to the filtering processing step, the compensation processing step and the synthesis calculation step, and then the vehicle posture signal is output; when the brake pedal is not pressed, the initial posture signal output by the IMU is directly calculated through the synthesis calculation step to output the vehicle posture signal, thereby realizing the processing of the vehicle posture signal.

[0033] The filtering processing step is used to filter the initial posture signal output by the IMU sensor to filter out the interference signal generated by the IMU sensor when the pedal is pressed, and obtain a filtered corrected posture signal;

[0034] The compensation processing step is used to compensate for the interference caused by the displacement of the IMU sensor due to the brake pedal being stepped on, and the compensation correction posture signal is obtained after compensating the filtered correction posture signal;

[0035] Synthetic calculation step: used to convert the compensated corrected posture signal or the initial posture signal into the posture signal at the center of mass of the vehicle. When the brake pedal is pressed, the initial posture signal output by the IMU sensor chip is successively subjected to the filtering processing step, the compensation processing step, and the synthetic calculation step to output the vehicle posture signal; when the brake pedal is not pressed, the posture signal output by the IMU sensor chip is subjected to the synthetic calculation step to output the vehicle posture signal.

[0036] The filtering processing step filters the initial posture signal through a filter, wherein the filter is configured as a variable frequency filter, and the cutoff frequency F of the filter matches the rate at which the brake pedal is depressed. A comparison table of the filter cutoff frequency and the brake pedal depression rate is set based on a pre-calibration, and the filter cutoff frequency is obtained by looking up the table by the brake pedal depression rate. When pre-calibrating, the cutoff frequency is set to have a negative correlation with the brake pedal depression rate, and the frequency and rate comparison table or MAP is set by the negative correlation.

[0037] The compensation processing step includes: obtaining a compensated posture signal corresponding to the brake pedal position through the pedal position after the brake pedal is pressed, and subtracting the compensation posture signal from the filtered corrected posture signal obtained in the filtering processing step to obtain the compensated corrected posture signal after compensation processing.

[0038] The present invention directly integrates the IMU sensor into the ECU of the integrated electronic brake module. In addition to the IMU sensor chip, no additional chip is required, which reduces the system cost and simplifies the assembly process of the vehicle in the production process. At the hardware level, the power chip, CAN interface chip and MCU in the original independent IMU sensor module are omitted, and the IMU sensor chip is directly arranged in the ECU of the integrated electronic brake module. The power supply of the main MCU in the integrated electronic brake module ECU is borrowed to directly connect the IMU sensor output signal to the main MCU. At the software level, by detecting the action of the brake pedal, when the driver steps on the brake pedal, the interference signal transmitted from the brake pedal to the IMU sensor chip is filtered out to avoid the erroneous detection of the vehicle running posture due to the change of the IMU sensor signal caused by the driver stepping on the brake. Integrating the IMU sensor chip into the integrated electronic brake module can reduce the system cost of the vehicle braking system and reduce the number of electronic modules and corresponding wiring harness connectors required for the assembly of the whole vehicle. It reduces the cost of the braking system on the vehicle for the main engine factory, and at the same time reduces the number of parts required on the vehicle and the corresponding management cost.

[0039] The filtering processing step, the compensation processing step and the synthesis calculation step in the processing step are introduced below through a specific implementation plan:

[0040] 1. Filtering process: Filter interference through frequency conversion filter:

[0041] When the driver brakes at different speeds, the interference to the sensor is different. The faster the brake is applied, the greater the impact and the greater the interference. In the present invention, a variable frequency filter is used to eliminate the interference. The filter can be implemented by software to eliminate the noise of the signal.

[0042] The filter cutoff frequency F is calculated by looking up the table through the brake pedal rate (Brake_Pedal_Position_Dot). The principle is that the greater the pedal rate, the smaller the frequency F, and the heavier the filtering; the corresponding relationship between speed and cutoff frequency F (comparison table) is expressed by the following formula:

[0043] F=f(Brake_Pedal_Position_Dot);

[0044] Under the above-mentioned control relationship, the corresponding cutoff frequency F can be obtained only by knowing the speed of the brake pedal; then the coefficient of the filter is calculated by F, and the initial posture signal (Ax_raw) output by the sensor is filtered to obtain the filtered corrected posture signal Ax_filter; where Filte(x) represents the mathematical expression of the filter, and x corresponds to the initial posture signal. The mathematical expression of the filter is as follows:

[0045] Ax_filter = Filter(Ax_raw);

[0046] 2. Compensation processing steps: Compensate the sensor signal

[0047] When the driver steps on the brake, the firewall will be deformed. When the firewall is deformed, the electronic brake module WCBS will tilt, and then an erroneous interference signal Ax_offset will be generated. This erroneous signal will affect the output posture signal of the IMU sensor chip, so compensation is required. In the present invention, Ax_offset is eliminated by compensation; Ax_offset is calculated by looking up the table through the brake pedal position (Brake_Pedal_Position), and it is subtracted from Ax_filter to obtain Ax_compensate; the cutoff frequency and rate comparison table and the brake pedal position and compensation Ax_offset comparison table are all pre-calibrated and adjusted through experiments.

[0048] The comparison table or comparison relationship between the brake pedal position and Ax_offset can be expressed by the following mathematical formula:

[0049] Ax_offset=f(Brake_Pedal_Position);

[0050] By pre-calibrating the comparison table or comparison relationship between the two, the position signal can be obtained after the brake pedal is stepped on, and then the Ax_offset data can be obtained through the comparison table; then the posture signal Ax_filter obtained after filtering is subtracted from its Ax_offset to obtain the compensated posture signal Ax_compensate:

[0051] Ax_compensate=Ax_filter-Ax_offset;

[0052] 3. Synthesis calculation steps: Synthesize sensor signals:

[0053] Since the position of WCBS on the whole vehicle is not the center of mass position, it needs to be converted to the position signal Ax_cg of the center of mass position. Ax_cg is the final vehicle position signal. The specific algorithm is as follows:

[0054] Ax_cg=Ax_compensate+Yaw_rate_dot*A+yaw_rate^2*B;

[0055] in:

[0056] -Yaw_rate: vehicle yaw rate;

[0057] -Yaw_rate_dot: vehicle yaw angular acceleration;

[0058] -A: the longitudinal distance between WCBS and the centroid;

[0059] -B: lateral distance between WCBS and the centroid;

[0060] The calculated Ax_cg is the final output vehicle posture signal.

[0061] like Figure 4 As shown, because the posture signal is a signal that is used only after the vehicle is started, the vehicle status is generally checked first. When the vehicle is in the ignition ECU working mode and the vehicle is in operation, it means that the posture signal is needed at this time, so the operation will be started at this time. When the brake pedal is pressed, the filtering processing step, the compensation processing step, and the synthesis calculation step are entered in sequence. Otherwise, the synthesis calculation step is directly entered to obtain the posture signal at the center of mass of the vehicle.

[0062] like Figure 3As shown, the processing method of the present application can be integrated into the central processing unit of the integrated electronic brake module in the form of a software algorithm. By running the algorithm to process the initial posture output by the IMU sensor, the posture signal at the center of mass of the vehicle is obtained to provide posture data for the control of the whole vehicle. This embodiment is implemented by software integration, with low cost and no hardware cost.

[0063] like Figure 3 What is shown is an electronic braking module provided by the present application, in which an IMU sensor chip is integrated. The electronic braking module is arranged on the vehicle firewall, and the IMU sensor signal processing method in the embodiment of the present application is used to process the initial posture signal output by the IMU sensor chip to obtain a vehicle posture signal. This integrated electronic braking module not only has the advantage of integration but also solves the defect of inaccurate posture output by the IMU chip caused by integration.

[0064] This embodiment also provides an IMU sensor signal processing system, wherein the IMU sensor is installed in an integrated electronic brake module on a vehicle firewall, the system includes a filtering processing unit, a compensation processing unit and a synthesis calculation unit, after the brake pedal is stepped on, the initial posture signal output by the IMU sensor chip is sent to the filtering processing unit; the filtering processing unit is configured to filter the initial posture signal output by the IMU sensor to filter out the interference signal generated by the IMU sensor when the pedal is stepped on, and obtain a filtered corrected posture signal;

[0065] The compensation processing unit is configured to compensate for the interference caused by the displacement of the IMU sensor due to the brake pedal being stepped on, and the compensation processing unit compensates the filtered corrected posture signal to obtain a compensated corrected posture signal;

[0066] The synthesis calculation unit is configured to convert the compensated corrected posture signal into a posture signal at the position of the vehicle's center of mass as a vehicle position signal;

[0067] When the vehicle brake pedal is not pressed, the initial posture signal output by the IMU sensor chip is directly sent to the synthesis calculation unit. At this time, the synthesis calculation unit is configured to convert the initial posture signal into a posture signal at the center of mass of the vehicle and use it as a vehicle position signal.

[0068] The filtering processing unit, the compensation processing unit and the synthesis calculation unit are respectively configured using the processing methods of the filtering processing step, the compensation processing step and the synthesis calculation step in the processing method of this embodiment to realize the processing and calculation functions.

[0069] After implementation, this solution not only solves the problem of electronic brake module integration, but also solves the problem of inaccurate IMU output caused by integration, and realizes the purpose of integrating IMU into WCBS. The IMU sensor chip is integrated into the ECU of the integrated electronic brake module. The integrated electronic brake module is installed on the vehicle firewall and integrates the brake pedal that the driver can operate. The software algorithm will detect the driver's action of stepping on the brake pedal, and filter out the interference of the brake pedal action on the IMU sensor signal output signal, ensuring that the output signal of the IMU sensor chip collected by the braking system can truly reflect the running posture of the vehicle.

[0070] Obviously, the specific implementation of the present invention is not limited to the above-mentioned methods. As long as various non-substantial improvements are made using the method concept and technical solution of the present invention, they are all within the protection scope of the present invention.

Claims

1. A method for processing an IMU sensor signal, wherein the IMU sensor is installed in an integrated electronic brake module on a vehicle firewall, characterized in that: The method comprises: processing an initial posture signal output by an IMU sensor based on a state of a brake pedal to obtain a corrected posture signal as a vehicle posture signal.

2. The method for processing an IMU sensor signal according to claim 1, wherein: The processing of the initial posture signal output by the IMU sensor based on the state of the brake pedal includes: A filtering process step, a compensation process step and a synthesis calculation step; The filtering processing step is used to filter the initial posture signal output by the IMU sensor to filter out the interference signal generated by the IMU sensor when the pedal is pressed, and obtain a filtered corrected posture signal; The compensation processing step is used to compensate for the interference caused by the displacement of the IMU sensor due to the brake pedal being stepped on, and the compensation correction posture signal is obtained after compensating the filtered correction posture signal; Synthesis calculation step: used to convert the posture signal into the posture signal at the center of mass of the vehicle.

3. The method for processing an IMU sensor signal as claimed in claim 2, characterized in that: The initial posture signal output by the IMU sensor is processed based on the brake pedal being pressed. When the brake pedal is pressed, the filtering process is performed; otherwise, the synthesis calculation process is performed.

4. The method for processing an IMU sensor signal according to claim 2, wherein: The filtering process step filters the initial posture signal through a filter, wherein the filter is configured as a variable frequency filter, and the cutoff frequency F of the filter matches the rate at which the brake pedal is depressed.

5. The method for processing an IMU sensor signal as claimed in claim 2, characterized in that: The compensation processing step includes: obtaining a compensated posture signal corresponding to the brake pedal position through the pedal position after the brake pedal is pressed, and subtracting the compensation posture signal from the filtered corrected posture signal obtained in the filtering processing step to obtain the compensated corrected posture signal after compensation processing.

6. The method for processing an IMU sensor signal as claimed in claim 2, characterized in that: The synthetic calculation step includes converting the posture signal to obtain a posture signal corresponding to the vehicle's center of mass position as the vehicle posture signal.

7. The method for processing an IMU sensor signal according to claim 4, characterized in that: A comparison table of filter cutoff frequency and brake pedal depression rate is pre-calibrated and set, and the filter cutoff frequency is obtained by looking up the table according to the brake pedal depression rate.

8. The method for processing an IMU sensor signal as claimed in claim 7, characterized in that: The cut-off frequency has a negative correlation with the brake pedal depression rate.

9. A processing system for an IMU sensor signal, wherein the IMU sensor is installed in an integrated electronic brake module on a vehicle firewall, characterized in that: The system includes a filtering processing unit, a compensation processing unit and a synthesis calculation unit. After the brake pedal is stepped on, the filtering processing unit is configured to filter the initial posture signal output by the IMU sensor to filter out the interference signal generated by the IMU sensor when the pedal is stepped on, and obtain a filtered corrected posture signal; The compensation processing unit is configured to compensate for the interference caused by the displacement of the IMU sensor due to the brake pedal being stepped on, and the compensation processing unit compensates the filtered corrected posture signal to obtain a compensated corrected posture signal; The synthesis calculation unit is configured to convert the posture signal into a posture signal at the vehicle's center of mass position as the vehicle position signal.

10. An electronic brake module, characterized in that: An IMU sensor chip is integrated in the electronic braking module, and the electronic braking module is arranged on the vehicle firewall. The initial posture signal output by the IMU sensor chip is processed using the IMU sensor signal processing method as described in any one of claims 1-8 to obtain a vehicle posture signal.

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