An automatic recording device and method for braking road tests

Abstract

This invention discloses an automatic recording device and method for braking road tests. The device includes a CAN reading module and a data processing module. The CAN reading module is connected to the vehicle's OBD interface. The CAN reading module acquires the real-time transmitted brake switch signal and vehicle speed signal from the vehicle's OBD interface and parses out the corresponding brake switch set signal and vehicle speed signal from the message. The data processing module acquires the brake switch set signal and vehicle speed signal parsed by the CAN reading module and processes them to obtain the data required for recording during the braking road test. The advantages of this invention are: by reading CAN messages through a hardware system and automatically parsing and recording them, the data during the test is statistically recorded, achieving accurate and reliable statistical data of the braking road test, providing accurate data support for subsequent vehicle performance, parameter, and reliability analysis.

Description

Technical Field

[0001] This invention relates to the field of road testing of automotive braking systems, and in particular to an automatic recording device and method for road braking tests. Background Technology

[0002] In passenger vehicle braking road tests, frequent braking is required, along with the recording of test data. This data is essential for subsequent vehicle analysis. For example, domestic OEMs often record data such as the number of braking actions, initial braking speed, and final braking speed throughout a road test cycle. Currently, the common recording method involves the driver manually pressing a counter on the gear shift lever to count the number of braking actions. Each time the brake is applied, the driver manually presses the counter, and the count is tallied after each test cycle. The main problems with this method are: it's easy to miss records; if the driver forgets to press the counter after braking, the number of braking actions will be missed. The recorded information is limited; this method only records the number of braking actions, and other information, such as braking speed, cannot be recorded. External speed measuring devices are still needed, making data recording cumbersome. Furthermore, this method can distract the driver, posing a safety risk. Summary of the Invention

[0003] The purpose of this invention is to overcome the shortcomings of the prior art and provide an automatic recording device and method for braking road tests. This device automatically collects data without relying on manual collection, and the collected data is accurate and reliable.

[0004] To achieve the above objectives, the technical solution adopted by the present invention is as follows: an automatic recording device for braking road tests, comprising a CAN reading module and a data processing module. The CAN reading module is connected to the vehicle's OBD interface. The CAN reading module obtains the messages corresponding to the brake switch signal and vehicle speed signal sent in real time from the vehicle's OBD interface and parses out the corresponding brake switch set signal and vehicle speed signal in the messages. The data processing module obtains the brake switch set signal and vehicle speed signal parsed by the CAN reading module and processes them to obtain the data to be recorded for the braking road test.

[0005] The data processing module is connected to the host computer and is used to upload the recorded data to the host computer for storage.

[0006] The data to be recorded for the braking road test includes the number of braking events and the initial braking speed, final braking speed, braking time, and average deceleration data for each braking event.

[0007] The data processing module is implemented using a microcontroller, which is connected to the CAN reading module via an SPI bus; the microcontroller is also connected to the host computer via a USB hardwire.

[0008] A recording method for an automatic recording device for braking road tests includes the following steps:

[0009] Before the test begins, connect the CAN reading module to the vehicle's OBD interface to complete the hard-wired connection with the vehicle.

[0010] After the experiment begins, the host computer sends a start command to the microcontroller. After receiving the start command, the microcontroller listens for bus messages from the vehicle's OBD port based on the CAN reading module.

[0011] The microcontroller uses the brake switch set signal and vehicle speed signal parsed by the CAN reading module to process and obtain the data required for the braking road test.

[0012] After the experiment is completed, the host computer sends a data request command to the microcontroller, and the microcontroller uploads the recorded data to the host computer for storage.

[0013] The CAN read module filters the read CAN messages, only receiving the two frames containing the brake pedal signal and vehicle speed. It then polls the two frames corresponding to the brake pedal signal and vehicle speed signal and sends them to the microcontroller.

[0014] The microcontroller records the braking data for each test. The microcontroller reads the brake pedal signal by polling. When it is determined from the brake pedal signal that the brake pedal has changed from not being pressed to being pressed, the braking begins. The microcontroller immediately reads the speed data from another frame of the message corresponding to the brake pedal signal and records it as the initial braking speed.

[0015] When the brake pedal signal changes from being depressed to being released, the braking action ends. The time between the brake pedal being depressed and being released is recorded as the single braking time for this action. At the same time, the final braking speed for this action is recorded based on the speed data in the message corresponding to the release of the brake pedal.

[0016] The microcontroller calculates the average deceleration corresponding to this braking action based on the initial braking velocity, the final braking velocity, and the single braking time.

[0017] The microcontroller records the initial braking speed, final braking speed, single braking time, and average deceleration corresponding to each braking action during the test, forming the data required for the braking road test.

[0018] The microcontroller records the initial braking velocity, final braking velocity, single braking time, and average deceleration for each braking action during the test, and saves the recorded data in a predefined structure array format; each structure member in the structure array includes the initial braking velocity, final braking velocity, single braking time, and average deceleration.

[0019] The total number of braking operations during the experiment is determined by the number of structure members in the structure array.

[0020] The microcontroller records the braking time for each braking action by using timer interrupts and counter increments.

[0021] The advantages of this invention are as follows: It uses a hardware system to read CAN messages and automatically parse and record data during the test process, ensuring accurate and reliable statistical data of braking road tests. This provides accurate data support for subsequent vehicle performance, parameter, and reliability analysis. The recording is accurate and reliable, without omissions. The hardware cost is low and implementation is convenient. Developed based on a microcontroller, it is simple, reliable, and highly compatible, applicable to various vehicle models. It requires only one driver to automatically record all braking data at a cost of less than 100 yuan, solving the practical need for braking test data acquisition and recording, greatly freeing up test personnel, simplifying driver operation, and improving driving safety. Attached Figure Description

[0022] The following is a brief explanation of the contents of each of the accompanying drawings and the markings in the drawings:

[0023] Figure 1 This is a schematic diagram of the automatic recording device for braking road tests according to the present invention. Detailed Implementation

[0024] The specific embodiments of the present invention will be further described in detail below with reference to the accompanying drawings and the description of the preferred embodiments.

[0025] This application primarily utilizes a microcontroller and CAN bus to collect, analyze, and upload data during braking tests. Compared to existing technologies that rely on manual counting to calculate braking frequency and speed, this application offers advantages such as accuracy, reliability, speed, low cost, and ease of implementation. The device automatically records all braking information during the test, including the number of braking actions, initial braking speed, final braking speed, braking time, and average deceleration. It can also communicate serially with a host computer (PC, tablet, mobile phone) to view current test data and export and save all data after completing a test cycle. The hardware consists of an Arduino nano microcontroller, an MCP2515 CAN module, and connecting wiring harnesses. The software utilizes Arduino IDE / C++ programming to control the internal data processing flow of the microcontroller and CAN module, enabling the acquisition of necessary braking and speed signals from the vehicle's OBD interface, algorithm invocation, and the processing and output of braking test data.

[0026] This invention utilizes the mature Arduino nano microcontroller development board and the MCP2515 CAN module. Through programming, it acquires real-time brake switch signals and vehicle speed signals from the vehicle's OBD port, and further parses the corresponding brake switch set signals and vehicle speed signals from these messages. An algorithm is then invoked to process and output the braking test data. This device automatically records all braking information during the test, including the number of braking actions, initial braking speed, final braking speed, braking time, and average deceleration. It can also communicate serially with a host computer (PC, tablet, mobile phone) to view the current test data and export and clear all data after completing a test cycle. This device automatically records all braking data with only one driver, solving the practical needs of data acquisition and recording at a cost of less than 100 yuan, greatly freeing up test personnel, simplifying driver operation, and improving driving safety.

[0027] like Figure 1 As shown, this application discloses an automatic recording device for braking road tests, comprising a CAN reading module and a data processing module. The CAN reading module is connected to the vehicle's OBD interface. The CAN reading module obtains the messages corresponding to the brake switch signal and vehicle speed signal sent in real time from the vehicle's OBD interface and parses out the corresponding brake switch set signal and vehicle speed signal in the messages. The data processing module obtains the brake switch set signal and vehicle speed signal parsed by the CAN reading module and processes them to obtain the data to be recorded for the braking road test.

[0028] The CAN read module uses the MCP2515 CAN chip, which connects to the vehicle's OBD interface via CANH and CANL pins to read data from the vehicle's CAN network. It can be connected to a connector compatible with the OBD interface for easy direct insertion. Since the vehicle's own CAN messages contain information such as vehicle speed and braking, this information only needs to be read by the CAN chip and sent to the data processing module for processing.

[0029] The data processing module is implemented using an Arduino nano microcontroller development board, which integrates a microcontroller. This application uses a 51 series microcontroller, which connects to a host computer to upload recorded data for storage. In terms of connectivity, the microcontroller connects to the CAN read module via an SPI bus; the microcontroller also connects to the host computer via a USB hardwired connection.

[0030] The microcontroller mainly processes the message frame data read from the CAN chip to obtain the information that needs to be recorded for the braking road test, including the number of braking operations and the initial braking speed, final speed, braking time, and average deceleration data corresponding to each braking operation.

[0031] The CAN chip has a built-in polling filter program to read CAN data and reduce the amount of data, thus reducing the workload of the microcontroller. It filters the read CAN messages, only receiving the two frames containing the brake pedal signal and vehicle speed. The microcontroller polls for these two frames and sends them to the microcontroller. These two frames represent the brake pedal signal and vehicle speed, respectively. Based on the brake pedal signal, the microcontroller determines whether braking has started, ended, and continues. Based on the vehicle speed signal, it records the vehicle speed data at the start and end of braking.

[0032] The host computer is a device such as a PC, tablet, or mobile phone, which connects to the microcontroller wirelessly or via wired connection to obtain the data recorded in the experiment, making it convenient to view and save.

[0033] The above describes the hardware components of the recording device of this application. This application also provides a recording method for an automatic recording device for braking road tests, comprising the following steps:

[0034] Before the test begins, connect the CAN reading module to the vehicle's OBD interface to complete the hard-wired connection with the vehicle.

[0035] After the experiment begins, the host computer sends a start command to the microcontroller. After receiving the start command, the microcontroller listens for bus messages from the vehicle's OBD port based on the CAN reading module.

[0036] The microcontroller uses the brake switch set signal and vehicle speed signal parsed by the CAN reading module to process and obtain the data required for the braking road test.

[0037] After the experiment is completed, the host computer sends a data request command to the microcontroller, and the microcontroller uploads the recorded data to the host computer for storage.

[0038] The microcontroller records each braking data point during the test. Each braking data point includes:

[0039] The microcontroller reads the brake pedal signal through polling. When it determines that the brake pedal has changed from being unpressed to being pressed based on the brake pedal signal, the braking begins. It immediately reads the speed data from another frame of the message corresponding to the brake pedal signal and records it as the initial braking speed.

[0040] When the brake pedal signal changes from being depressed to being released, the braking action ends. The time between the brake pedal being depressed and being released is recorded as the single braking time for this action. At the same time, the final braking speed for this action is recorded based on the speed data in the message corresponding to the release of the brake pedal.

[0041] The microcontroller calculates the average deceleration corresponding to this braking action based on the initial braking velocity, the final braking velocity, and the single braking time.

[0042] The microcontroller records the initial braking speed, final braking speed, single braking time, and average deceleration corresponding to each braking action during the test, and saves the data required for the braking road test. After receiving the command from the host computer to end the test, the microcontroller sends the saved data recorded from the start to the end of the test to the host computer for storage and viewing.

[0043] The microcontroller records the initial braking velocity, final braking velocity, single braking time, and average deceleration for each braking action during the experiment. The recorded data is stored in a predefined structure array. Each member of the structure array includes the initial braking velocity, final braking velocity, single braking time, and average deceleration. During storage in the microcontroller, this application pre-sets a structure array to store the recorded initial braking velocity, final braking velocity, single braking time, and average deceleration for each braking action. The maximum number of members in the structure array is predefined to be 200, as the maximum number of braking actions in traditional experiments is 200. Each braking action is recorded as a member, and the data is stored in the structure array for easy data recording. Simultaneously, the total number of braking actions during the experiment can be easily determined based on the number of members in the structure array. After the experiment ends and the host computer sends a termination command, the microcontroller uploads the structure array to the host computer. The host computer can quickly determine the number of braking operations based on the number of members in the structure array. Alternatively, an algorithm can be used to automatically record the number of members in the structure array to determine the number of braking operations during the experiment.

[0044] The microcontroller used in this solution is the Arduino-Nano, a commonly used 51 series microcontroller. This microcontroller has more powerful functions, a smaller size, and rich standard I / O, serial ports, and AD converters. It has its own IDE and uses C++ language programming, which makes the statements simpler and clearer.

[0045] 1. Hardware Connection: The MCP2515 module is connected to the corresponding I / O port of the Arduino Nano development board via the SPI bus, as shown in the figure above. The CAN H / L of the MCP2515 module is also hard-wired to the 6 / 14 pins of the vehicle's OBD port to realize CAN communication. It is hard-wired to the host computer via USB to realize serial communication and power supply.

[0046] 2. Program Architecture: The program first defines a structure array with a maximum size of 200 (greater than the total number of braking events possible in a single Huangshan braking test). Structure members include initial braking speed, final braking speed, single braking time, and average deceleration. To reduce the load on the microcontroller (MCU), CAN message filtering for the MCP2515 module is configured during program initialization, receiving only two frames of messages containing the brake pedal signal (brake switch) and vehicle speed. Simultaneously, a timer interrupt is enabled, and the main program polls the brake pedal signal and the corresponding two frames of messages for the vehicle speed signal. When the pedal signal changes, the appropriate processing function is executed.

[0047] 3. Start Recording: When the driver starts the test, he can send a start command to the recording device through the host computer (mobile phone, tablet, laptop). The program has a serial port interrupt function. When the host computer receives the specified hexadecimal instruction, such as "OXFF", the system sets the CAN module to normal mode and starts listening for bus messages from the vehicle's OBD port.

[0048] 4. Brake pedal depressed: When the program polls and finds that the pedal light is on, it indicates that the brake pedal is depressed. The current vehicle speed is immediately parsed from another frame as the initial braking speed. At the same time, the timer interrupt is enabled. The timer interrupt is triggered every 5 milliseconds, and the interrupt routine is entered to increment the counter.

[0049] 5. Brake Release: When the program polls and finds that the brake pedal light is off, it indicates that the brake pedal has been released. The current vehicle speed is immediately parsed from another message frame as the final braking speed, and the timer interrupt is disabled. The total accumulator value at this point is the single braking time for this test.

[0050] 6. Data Processing: After obtaining the initial braking velocity, final braking velocity, and the total value of the timer accumulator (which increments every 5ms), the total accumulator value multiplied by 5 / 1000 represents the single braking time in seconds. The initial and final velocities are then converted from km / h to m / s. By dividing (initial velocity - final velocity) by the single braking time, the average deceleration of the single braking event is obtained. These data are then stored in the corresponding members of the structure array, completing the data processing.

[0051] 7. Data Output: When a test cycle ends, the tester sends a data request command to the device through the host computer. The program has a serial port interrupt function. When the specified hexadecimal command, such as "OX00", is received from the host serial port, the device will output the recorded structure array to the host computer in a loop according to the number of times it is recorded, so that the tester can save it.

[0052] 8. Data Clearing: After completing a test cycle and saving the data, the tester can send a command to the device via the host computer in the same way, such as "0XF0". Upon receiving this command, the program will clear all the contents of the structure array, set all flags, and wait for the start of the next cycle.

[0053] Obviously, the specific implementation of this invention is not limited to the above-described methods. Any non-substantial improvements made using the inventive concept and technical solution of this invention are within the protection scope of this invention.

Claims

1. A recording method for an automatic recording device for braking road tests, characterized in that: The device includes a CAN reading module and a data processing module. The CAN reading module is connected to the vehicle's OBD interface. The CAN reading module obtains the messages corresponding to the brake switch signal and vehicle speed signal sent in real time from the vehicle's OBD interface and parses out the corresponding brake switch set signal and vehicle speed signal in the messages. The data processing module obtains the brake switch set signal and vehicle speed signal parsed by the CAN reading module and processes them to obtain the data to be recorded for the braking road test. The data processing module is connected to the host computer and is used to upload the recorded data to the host computer for storage. The data to be recorded for the braking road test includes the number of braking operations and the initial braking speed, final speed, braking time, and average deceleration data for each braking operation. The data processing module is implemented using a microcontroller, which is connected to the CAN reading module via an SPI bus; the microcontroller is also connected to the host computer via a USB hardwire. The method includes the following steps: Before the test begins, connect the CAN reading module to the vehicle's OBD interface to complete the hard-wired connection with the vehicle. After the experiment begins, the host computer sends a start command to the microcontroller. After receiving the start command, the microcontroller listens for bus messages from the vehicle's OBD port based on the CAN reading module. The microcontroller records the brake switch set signal and vehicle speed signal parsed by the CAN reading module and processes them to obtain the data required for the braking road test. After the experiment is completed, the host computer sends a data request command to the microcontroller, and the microcontroller uploads the recorded data to the host computer for storage. The CAN read module filters the read CAN messages and only receives the two frames containing the brake pedal signal and vehicle speed. It polls the two frames corresponding to the brake pedal signal and vehicle speed signal and sends them to the microcontroller. The microcontroller records each braking data during the test. The microcontroller reads the brake pedal signal by polling. When it is determined from the brake pedal signal that the brake pedal has changed from not being pressed to being pressed, the braking begins. The speed data is immediately taken from another frame of the message corresponding to the brake pedal signal and recorded as the initial braking speed. When the brake pedal signal changes from depressed to released, the braking action ends. The time between the brake pedal being depressed and released is recorded as the single braking time for this action. At the same time, the final braking speed for this action is recorded based on the speed data in the message corresponding to the release of the brake pedal. The microcontroller records the initial braking velocity, the final braking velocity, and the single braking time to calculate the average deceleration corresponding to this braking action. The microcontroller records the initial braking speed, final braking speed, single braking time, and average deceleration corresponding to each braking action during the test, forming the data required for the braking road test. The microcontroller records the initial braking velocity, final braking velocity, single braking time, and average deceleration for each braking action during the test, and saves the recorded data in a predefined structure array format; each structure member in the structure array includes the initial braking velocity, final braking velocity, single braking time, and average deceleration. The total number of braking operations during the experiment is determined by the number of structure members in the structure array; The microcontroller records the braking time for each braking action by using timer interrupts and counter increments.

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