Unmanned vehicle overspeed detection and brake failure emergency braking method and system

Abstract

The invention discloses an unmanned vehicle overspeed detection and brake failure emergency braking method and system. The system adopted by the braking method comprises a rotating speed sensing module, an unmanned vehicle overspeed monitoring and control module and a power supply emergency cut-off device. The method comprises the steps that the linear Hall sensor is installed at a motor rotor magnet, a magnetic signal is converted into a periodic voltage signal, the data resolving and processing module carries out wavelet transformation on a digital signal, the data resolving and processing module carries out fast Fourier transformation on the digital signal, and the periodic voltage signal is obtained. A speed monitoring unit of the unmanned vehicle overspeed monitoring and control module receives motor instantaneous frequency provided by the rotating speed sensing module; the data resolving and processing module transmits the calculated rotating speed of the motor to the unmanned vehicle overspeed monitoring and control module, the real-time rotating speed is compared with a safety threshold value to judge whether overspeed occurs or not, and the power supply emergency cut-off device cuts off a power supply after receiving a signal. By sensing and controlling the rotating speed of the wheels, a power supply is cut off when the unmanned vehicle is overspeed and a brake system fails, so that accidents are avoided.

Description

Technical Field

[0001] The present invention relates to the technical field of unmanned vehicle driving safety, and in particular to an unmanned vehicle overspeed detection and brake failure emergency braking method and system. Background Art

[0002] Speeding and loss of control is one of the main risk factors affecting the safety of unmanned vehicles. Speeding and loss of control of unmanned vehicles usually refers to the situation where the speed of an unmanned vehicle exceeds the designed safe speed range due to various reasons (such as control system failure, sensor failure, external interference, etc.) and cannot be reduced to a safe range through normal control means (such as braking, deceleration, etc.). This situation can easily lead to serious traffic accidents and threaten the safety of passengers, pedestrians and other road users.

[0003] At present, some emergency braking systems and methods have been proposed and applied in actual scenarios to address the problem of speeding and loss of control of unmanned vehicles. The safety system of existing unmanned vehicles relies on the reliability of the main braking system and the electronic control unit (ECU). However, the failure of a single system (such as sensor drift, software logic errors, or mechanical brake failure) may lead to fatal risks such as overspeeding or brake failure. Although some solutions attempt to introduce redundant designs, they often rely on multi-sensor fusion technology, resulting in high system complexity and rising costs. In addition, the real-time and consistency of multi-source data fusion are difficult to guarantee. There are problems such as high dependence on computing power, significant delay, and high risk of fault propagation, which may introduce new fault points. In addition, traditional redundant braking systems mostly use a backup mechanism that is isomorphic to the main system. Under extreme conditions, they may fail simultaneously due to common faults (such as power outage), and true safety redundancy cannot be achieved.

[0004] The single magnetic sensing channel is combined with an adaptive filtering algorithm to directly measure the motor speed and independently calculate the vehicle speed. Hardware-level isolation ensures that data acquisition is not affected by main system failures. Compared with traditional solutions, the single sensor architecture reduces the risk of signal conflict. At the same time, through dynamic calibration and error compensation models, it achieves accuracy that is no less than that of multi-sensor fusion, providing an independent, low-latency decision-making basis for redundant braking.

[0005] In summary, how to ensure the driving safety of unmanned vehicles and improve the real-time and reliability of emergency braking when the unmanned vehicle is speeding and out of control is a technical problem that needs to be solved urgently. Summary of the invention

[0006] Purpose of the invention: In view of the problems of overspeeding and brake system failure that occur during the driving of existing unmanned vehicles, as well as the problems and challenges of current emergency braking devices, the present invention proposes an unmanned vehicle overspeed detection and brake failure emergency braking method and system, which aims to quickly cut off the power supply and stop the vehicle safely when the unmanned vehicle exceeds the speed and the brake system fails through high-precision wheel speed sensing and intelligent control strategies, thereby effectively avoiding accidents.

[0007] Technical solution: The unmanned vehicle overspeed detection and brake failure emergency braking method of the present invention is implemented by an emergency braking system, which includes a speed sensing module, an unmanned vehicle overspeed monitoring and control module and a power emergency cut-off device.

[0008] Among them, the speed sensing module includes a linear Hall sensor, a magnetic sensor, an amplifying and filtering circuit, a digital-to-analog converter ADC, and a data solving and processing module; the linear Hall sensor is connected to the amplifying and filtering circuit; the amplifying and filtering circuit is connected to the data solving and processing module; the data solving and processing module is connected to the unmanned vehicle speeding monitoring and control module.

[0009] The linear Hall sensor is installed near the wheel motor of the unmanned vehicle. The magnetic sensor is used to collect the magnetic field changes generated by the rotation of the wheel motor rotor, convert the mechanical rotation into a magnetic signal, and convert the magnetic signal into a periodic voltage signal for output; the amplification and filtering circuit amplifies and filters the collected signal to remove noise and enhance the signal; the digital-to-analog converter ADC converts the filtered analog voltage signal into a digital signal and outputs it to the data solution and processing module; after receiving the digital signal, the data solution and processing module uses wavelet transform to filter out low-frequency noise and retain the useful components of the signal, and then performs a 256-point fast Fourier transform FFT on the filtered signal to extract the spectral components in the signal; the data solution and processing module uses the frequency with the largest energy in the spectrum as the instantaneous frequency of the motor speed, provides basic data for the speed monitoring system of the unmanned vehicle, and realizes real-time monitoring of the speed of the wheel motor of the unmanned vehicle.

[0010] The unmanned vehicle overspeed monitoring and control module includes a speed monitoring unit, a braking system control unit, a communication module, a power emergency cut-off system control unit and a visualization interface; wherein the speed monitoring unit is connected to the data solution and processing module and the visualization interface respectively through the communication interface; the braking system control unit is connected to the speed monitoring unit; and the power emergency cut-off system control unit is connected to the braking system control unit.

[0011] The speed monitoring unit of the unmanned vehicle overspeed monitoring and control module receives the motor instantaneous frequency information provided by the speed sensing module, and transmits the real-time speed of the unmanned vehicle to the visualization interface through the communication module, thereby realizing real-time transmission and display of data.

[0012] At the same time, the speed monitoring unit is also responsible for determining whether the speed of the unmanned vehicle is within the operating range ODD designed by the system; if the judgment result is that the speed is within the system design range ODD, the speed monitoring unit sends a signal to the visual interface; the visual interface displays normal driving; if the judgment result is that the speed of the unmanned vehicle exceeds the system design range ODD, the speed monitoring unit sends a signal to the brake system control unit to trigger the emergency braking procedure; after receiving the overspeed signal, the brake system control unit sends a brake deceleration command to the brake system and starts a timer to monitor the reaction time of the brake system; the timer is used to ensure that the brake system can reduce the speed to a safe range within a preset time; if the unmanned vehicle successfully decelerates to a safe range within the preset time of the timer, indicating that the brake system is working normally, the brake system control unit will send a signal to the visual interface, and the interface will then display that the vehicle has resumed normal driving; if the speed fails to drop to a safe range within the preset time of the timer, it indicates that the brake system may fail; at this time, the brake control system sends a signal to the power emergency cut-off system control module to trigger the power emergency cut-off procedure; the power emergency cut-off control module sends a power cut-off command to the power emergency cut-off device to perform emergency braking to ensure that the unmanned vehicle stops safely.

[0013] When the power emergency cut-off device receives the power cut-off signal from the unmanned vehicle overspeed monitoring and control module, it immediately performs the power cut-off operation; this operation causes the unmanned vehicle to lose its power source and slow down, and finally stop completely; this process implements the emergency braking function to prevent accidents. After the power cut-off operation is completed, the power emergency cut-off device further sends a signal that the operation is completed to the visual interface; after receiving the signal, the visual interface will display a prompt message of "Vehicle failure, power has been cut off"; it ensures the transparency of the emergency braking process, and also provides users with instant feedback, clearly indicating the current status of the vehicle and the safety measures taken.

[0014] Another object of the present invention is to propose a method for detecting overspeeding and emergency braking of an unmanned vehicle by a magnetic sensor, which is achieved by measuring the real-time speed of the wheel motor of the unmanned vehicle and controlling the braking when the speed of the unmanned vehicle exceeds the design range (ODD).

[0015] The unmanned vehicle overspeed detection and brake failure emergency braking method of the present invention comprises the following steps:

[0016] (1) In the measurement of wheel motor speed of unmanned vehicles, the linear Hall sensor is installed at the position of the motor rotor magnet. When the motor rotor rotates, the magnetic field changes periodically. The change in magnetic field strength causes the Hall voltage V H The periodic change of the Hall voltage V HThe signal processing circuit inside the linear Hall sensor amplifies the Hall voltage and converts it into a standard voltage signal output to form a periodic waveform.

[0017] (2) The amplitude of the periodic voltage signal output by the Hall sensor is small and contains high-frequency noise such as electromagnetic interference or sensor internal noise. The periodic voltage signal output by the linear Hall sensor is input into the amplification and filtering circuit, and an operational amplifier is used to form a non-inverting or inverting amplification circuit. By adjusting the feedback resistor R f and input resistance R in resistance, increase the amplitude of the periodic voltage signal, and adjust the Hall voltage V H The amplitude range; by adjusting the cut-off frequency f c , filter out high-frequency noise in the system such as switching noise or electromagnetic interference, while retaining the low-frequency component of the signal, namely the periodic voltage signal; then convert the filtered analog voltage signal into a digital signal D(t) through the digital-to-analog converter ADC for subsequent digital signal processing.

[0018] (3) The data calculation and processing module performs wavelet transform on the digital signal D(t) converted by the digital-to-analog converter ADC, using the continuous wavelet transform formula Decompose the signal, filter out high frequency noise and reconstruct the signal Extract the key features of the signal; where D'(t) represents the signal reconstructed by wavelet transform, that is, the motor speed characteristic signal after removing electromagnetic interference and mechanical vibration noise; j represents the number of layers (scale levels) of wavelet decomposition, and the value range is j=1,2,…,J, where J is the maximum number of decomposition layers; a represents the size parameter, that is, controls the degree of expansion and contraction of the wavelet function, a>0; b represents the translation parameter, that is, controls the position of the wavelet function on the time axis, b∈R; W j (a,b) represents the j-th wavelet coefficient, which indicates the difference between the signal and the wavelet basis function ψ at scale a and translation b. j The degree of matching; Represents the wavelet basis function, the mother wavelet function after scaling by a and translation by b.

[0019] (4) The data solution and processing module performs a fast Fourier transform (FFT) of 256 discrete data points on the filtered digital signal D'(t), converts the time domain signal into a frequency domain signal X(k), obtains the signal spectrum, and extracts the frequency f with the largest energy in the amplitude spectrum |X(k)| max = arg max k |X(k)| is the characteristic frequency of the motor speed.

[0020] (5) The data calculation and processing module extracts the frequency f with the largest energy from the FFT result X(k) max, this frequency point corresponds to the instantaneous frequency of the motor, and the real-time speed n of the motor is calculated, where P is the number of motor pole pairs.

[0021] (6) The data calculation and processing module outputs the calculated real-time motor speed n to the unmanned vehicle overspeed monitoring and control module by comparing the real-time speed n with the safety threshold n. th Determine whether it is overspeeding, and in the overspeed state, according to the speed deviation Δn=nn th Calculate the braking torque T = K p ·Δn+K i ∫Δndt realizes braking control; if the brake fails, the power emergency cut-off system is triggered. The braking control process is:

[0022] (6.1) The speed monitoring unit receives the instantaneous frequency information of the motor from the speed sensing module; at the same time, the speed monitoring unit transmits the real-time speed data of the unmanned vehicle to the visualization interface through the communication interface to realize real-time display of the data.

[0023] (6.2) The speed monitoring unit calculates the vehicle speed based on the motor speed n and the wheel radius r By judging the condition v min ≤v≤v max Determine whether the real-time speed of the unmanned vehicle is within the design range (ODD) of the system design; at the same time, dynamically adjust the ODD range according to the environmental perception data;

[0024] (6.3) If it is detected that v>v max , it indicates that the vehicle speed exceeds the unmanned vehicle speed design interval ODD, and the speed monitoring unit generates an overspeed signal S over =1 and sent to the control unit, triggering the emergency braking program and controlling the brake pressure Increment and start timer T.

[0025] (6.4) The brake system control unit monitors the brake system's response time t through the timer T. brake , if t brake >t max , the backup braking mechanism is triggered and the power emergency cut-off system is started to ensure that the braking system reduces the vehicle speed to a safe range within the preset time.

[0026] (6.5) If the unmanned vehicle decelerates to a safe zone within the preset time of the timer, the braking system control unit sends a signal to the visual interface, and the visual interface shows that the vehicle has resumed normal driving.

[0027] (6.6) If the vehicle speed does not drop to a safe range within the preset time of the timer, it indicates that the brake system has failed; the brake system control unit sends a signal to the power emergency cut-off system control unit to trigger the power emergency cut-off procedure.

[0028] (6.7) After receiving the signal, the power emergency cut-off system control unit sends a power cut-off command to the power emergency cut-off device; the power emergency cut-off device executes the power cut-off operation, causing the unmanned vehicle to lose power and gradually slow down until it stops completely.

[0029] (6.8) After executing the power-off operation, the power emergency cut-off device sends a signal to the visual interface, which displays "Vehicle failure, power cut off" to inform the user that the vehicle has entered the emergency braking state.

[0030] In step (1), when the rotor rotates, the magnetic field changes periodically. According to the Hall effect, the change in magnetic field strength causes the Hall voltage V H The periodic change of is expressed as:

[0031]

[0032] Where I is the current passing through the linear Hall sensor; B is the magnetic induction intensity of the external magnetic field; R H is the Hall coefficient; d is the material thickness.

[0033] In step (2), the periodic voltage signal output by the linear Hall sensor is input into the amplification filter circuit, and an operational amplifier is used to form a common-phase or inverting amplification circuit with an amplification factor of A. v for: R f is the feedback resistor, R in is the input resistance.

[0034] In step (3), the data calculation and processing module performs wavelet transform on the digital signal D(t) converted by the digital-to-analog converter, and uses the formula Decompose the signal; where W(a,b) represents the matching degree of the signal D(t) with the wavelet basis function ψ at scale a and translation b; a represents the size parameter that controls the degree of expansion and contraction of the wavelet function, a>0; b represents the translation parameter that controls the position of the wavelet function on the time axis, b∈R; D(t) represents the input signal, which represents the original voltage signal of the Hall sensor; t represents the time variable, Represents the mother wavelet function ψ(t) after scaling and translation.

[0035] In step (4), the data solution and processing module performs fast Fourier transform on the filtered digital signal D'(t), and uses the formula Convert the time domain signal into the frequency domain signal X(k) to obtain the spectrum of the signal.

[0036] In step (5), the data solution and processing module extracts the frequency f with the maximum energy from the frequency domain signal X(k) max is the instantaneous frequency of the corresponding motor, through The real-time speed n of the motor is calculated, where P is the number of motor pole pairs.

[0037] Beneficial effects: Compared with the prior art, the present invention has the following advantages:

[0038] (1) The real-time speed sensing module in the unmanned vehicle overspeed detection and brake failure emergency braking system of the present invention realizes high-precision measurement of the real-time speed of the wheel motor by combining the magnetic sensor and the data solution and processing module, thereby providing reliable data support for the speed monitoring of the unmanned vehicle.

[0039] (2) The unmanned vehicle speeding monitoring and control module in the present invention integrates functions such as speed monitoring, braking control and power cut-off. Through the efficient collaboration between various components, comprehensive monitoring of the unmanned vehicle speed and effective braking in emergency situations are achieved.

[0040] (3) The visual interface of the present invention provides the user with clear vehicle status information, enhances the user interactivity of the system and the timeliness of information transmission, and improves the user's understanding and control of the vehicle status.

[0041] (4) In the event of a brake system failure, the power emergency cut-off system control unit of the present invention sends a power cut-off command to the power emergency cut-off device to execute emergency braking to ensure that the unmanned vehicle stops safely.

[0042] (5) The present invention realizes the accurate monitoring of the real-time speed of the unmanned vehicle, the triggering of emergency braking in the case of overspeeding, and the emergency power cut-off function in the event of brake failure, thereby solving the problems of overspeeding and brake system failure that currently occur during the driving of unmanned vehicles and improving the driving safety of unmanned vehicles. BRIEF DESCRIPTION OF THE DRAWINGS

[0043] Figure 1 The structure diagram of the unmanned vehicle overspeed detection and brake failure emergency braking system of the present invention. DETAILED DESCRIPTION

[0044] like Figure 1As shown, the unmanned vehicle overspeed detection and brake failure emergency braking system of this embodiment includes: a speed sensing module, an unmanned vehicle overspeed monitoring and control module, and a power emergency cut-off device. Among them, the speed sensing module includes a linear Hall sensor, a magnetic sensor, an amplifying filter circuit, and a data solution and processing module; the linear Hall sensor is installed near the wheel motor of the unmanned vehicle, and the magnetic sensor collects the magnetic field changes generated by the rotation of the wheel motor rotor, converts the mechanical rotation into a magnetic signal, and converts the magnetic signal into a periodic voltage signal output; the amplifying filter circuit amplifies and filters the collected signal to remove noise and enhance the signal; the digital-to-analog converter ADC converts the filtered analog voltage signal into a digital signal and outputs it to the data solution and processing module; after receiving the digital signal, the data solution and processing module filters out the low-frequency noise through wavelet transform, retains the useful components of the signal, and then performs a 256-point fast Fourier transform (FFT) on the filtered signal to extract the spectrum components in the signal; the data solution and processing module uses the frequency with the largest energy in the spectrum as the instantaneous frequency of the motor speed to provide basic data for the speed monitoring system of the unmanned vehicle.

[0045] The unmanned vehicle overspeed monitoring and control module includes a speed monitoring unit, a braking system control unit, a power emergency cut-off system control unit and a visual interface; the speed monitoring unit is connected to the data solution and processing module and the visual interface through the communication interface, receives the motor instantaneous frequency information provided by the speed sensing module, and transmits the real-time speed of the unmanned vehicle to the visual interface through the communication module; at the same time, the speed monitoring unit is also responsible for judging whether the speed of the unmanned vehicle is within the system design operating range ODD. If the judgment result is that the speed is within the system design range ODD, the speed monitoring unit sends a signal to the visual interface to display normal driving; if the judgment result is that the speed of the unmanned vehicle exceeds the system design range ODD, the speed monitoring unit sends a signal to the braking system control unit to trigger the emergency braking procedure; after receiving the overspeed signal, the braking system control unit immediately sends a braking deceleration instruction to the braking system and starts a timer to monitor the reaction time of the braking system; the timer is used to ensure that the braking system reduces the speed to a safe range within a preset time; if the unmanned vehicle successfully decelerates to a safe range within the time preset by the timer, indicating that the braking system is working normally, the braking system control unit will send a signal to the visual interface, and the visual interface will then display that the vehicle has returned to normal driving. If the vehicle speed does not drop to a safe range within the preset time of the timer, it indicates that the brake system has failed; at this time, the brake control system sends a signal to the power emergency cut-off system control module, triggering the power emergency cut-off procedure.

[0046] When the power emergency cut-off device receives the power cut-off signal from the unmanned vehicle overspeed monitoring and control module, the device will immediately perform the power cut-off operation; after the power cut-off operation is completed, the power emergency cut-off device further sends the operation completion signal to the visual interface. After receiving the signal, the visual interface will display the prompt message "Vehicle failure, power cut off".

[0047] The unmanned vehicle overspeed detection and brake failure emergency braking method of this embodiment includes the following steps:

[0048] (1) The speed sensing module uses a linear Hall sensor installed near the wheel motor of the unmanned vehicle to collect the magnetic field changes generated by the rotation of the motor rotor, convert it into a periodic voltage signal, and obtain the Hall voltage V H , the expression is:

[0049]

[0050] Where I is the current passing through the linear Hall sensor; B is the magnetic induction intensity of the external magnetic field; R H is the Hall coefficient; d is the material thickness.

[0051] The signal processing circuit inside the linear Hall sensor amplifies the Hall voltage and converts it into a standard voltage signal output to form a periodic waveform.

[0052] (2) Amplify and filter the periodic voltage signal output by the Hall sensor of the filter circuit to remove noise and enhance the useful signal; f and input resistance R in resistance, increase the amplitude of the signal, and change the Hall voltage V H Adjust to the appropriate amplitude range; at the same time, use RC low-pass filter to filter out unnecessary noise, and its cut-off frequency f c Determined by the resistor R and the capacitor C:

[0053]

[0054] By adjusting the cut-off frequency f c , filter out high-frequency noise (such as switching noise or electromagnetic interference) in the system, while retaining the low-frequency component of the signal (i.e., periodic voltage signal); then convert the filtered analog voltage signal into a digital signal D(t) through a digital-to-analog converter (ADC) for subsequent digital signal processing;

[0055] (3) The data calculation and processing module performs wavelet transform filtering on the digital signal converted by the ADC to further filter out low-frequency noise and retain the useful components in the signal; through the continuous wavelet transform formula Decompose the signal, filter out high frequency noise and reconstruct the signal Extract key features from the signal;

[0056] Where D'(t) represents the signal reconstructed by wavelet transform, that is, the motor speed characteristic signal after removing electromagnetic interference and mechanical vibration noise; j represents the number of layers (scale levels) of wavelet decomposition, and the value range is j = 1, 2, ..., J, where J is the maximum number of decomposition layers; a represents the size parameter, that is, the degree of expansion and contraction of the wavelet function, a>0; b represents the translation parameter, that is, the position of the wavelet function on the time axis, b∈R; W j (a,b) represents the j-th wavelet coefficient, which indicates the difference between the signal and the wavelet basis function ψ at scale a and translation b. j The degree of matching; Represents the wavelet basis function, the mother wavelet function after scaling by a and translation by b.

[0057] (4) The data calculation and processing module performs a 256-point fast Fourier transform (FFT) on the filtered digital signal, and uses the DFT formula Convert the time domain signal into a frequency domain signal X(k), extract the spectrum in the signal, and extract the frequency f with the maximum energy in the amplitude spectrum |X(k)| max = arg max k |X(k)| is the characteristic frequency of the motor speed.

[0058] (5) The data solution and processing module extracts the frequency with the largest energy from the FFT result, and uses this frequency as the instantaneous frequency of the motor speed; the real-time speed of the motor is calculated.

[0059] (6) The data calculation and processing module transmits the calculated instantaneous frequency data of the motor to the speed monitoring unit of the unmanned vehicle overspeed monitoring and control module through the communication interface. The braking control process is:

[0060] (6.1) The speed monitoring unit receives the instantaneous frequency information of the motor from the speed sensing module; at the same time, the speed monitoring unit transmits the real-time speed data of the unmanned vehicle to the visualization interface through the communication interface to realize real-time display of the data.

[0061] (6.2) The speed monitoring unit determines whether the real-time speed of the unmanned vehicle is within the design interval ODD of the system.

[0062] (6.3) If the vehicle speed exceeds the unmanned vehicle speed design range ODD, the speed monitoring unit sends an overspeed signal to the brake system control unit, triggering the emergency braking procedure.

[0063] (6.4) Upon receiving the overspeed signal, the brake system control unit immediately sends a brake deceleration command to the brake system; at the same time, the brake system control unit starts a timer to monitor the response time of the brake system to ensure that the brake system can reduce the vehicle speed to a safe range within the preset time.

[0064] (6.5) If the unmanned vehicle successfully decelerates to a safe range within the preset time of the timer, the braking system control unit sends a signal to the visual interface, which then displays that the vehicle has returned to normal driving status.

[0065] (6.6) If the vehicle speed fails to drop to a safe range within the preset time of the timer, it indicates that the brake system may have failed; the brake system control unit sends a signal to the power emergency cut-off system control unit to trigger the power emergency cut-off procedure.

[0066] (6.7) After receiving the signal, the power emergency cut-off system control unit sends a power cut-off instruction to the power emergency cut-off device; the power emergency cut-off device executes the power cut-off operation, causing the unmanned vehicle to lose power and gradually slow down until it stops completely;

[0067] (6.8) After executing the power-off operation, the power emergency cut-off device sends a signal to the visual interface, which displays "Vehicle failure, power cut off" to inform the user that the vehicle has entered the emergency braking state.

[0068] The visualization interface of the present invention realizes displaying measurement results and providing control functions. The interface adopts a graphical interface or a command line interface. The specific design needs to be selected according to user needs and system complexity. In addition, the visualization interface is also responsible for displaying the status information of the vehicle. For example, after the power emergency cut-off device performs the power cut-off operation, the interface displays "Vehicle failure, to cut off the power", notifying the user that the vehicle has entered the emergency braking state. Such a design not only ensures the transparency of the emergency braking process, but also provides users with instant feedback, clearly indicating the current status of the vehicle and the safety measures taken.

[0069] Finally, it should be noted that the purpose of publishing the embodiments is to help further understand the present invention, but those skilled in the art can understand that various substitutions and modifications are possible without departing from the spirit and scope of the present invention and the appended claims. Therefore, the present invention should not be limited to the contents disclosed in the embodiments, and the scope of protection claimed by the present invention shall be subject to the scope defined in the claims.

Claims

1. A method for detecting overspeed and emergency braking of an unmanned vehicle due to brake failure, characterized in that: The unmanned vehicle overspeed detection and brake failure emergency braking system according to claim 1 is implemented, and the emergency braking method comprises the following steps: (1) The linear Hall sensor is installed on the motor rotor magnet. When the motor rotor rotates, the change in magnetic field strength causes the Hall voltage V H The periodic change of the Hall voltage V H ,The linear Hall sensor amplifies the Hall voltage and converts it into a periodic voltage signal; (2) The periodic voltage signal is input into the amplification and filtering circuit, and an operational amplifier is used to form a common-phase or anti-phase amplification circuit. By adjusting the feedback resistor R f and input resistance R in The resistance value increases the amplitude of the periodic voltage signal and adjusts the Hall voltage V H amplitude range; filter out high-frequency noise and retain the periodic voltage signal; convert the filtered analog voltage signal into a digital signal D(t) through a digital-to-analog converter; (3) The data calculation and processing module performs wavelet transform on the digital signal D(t) converted by the digital-to-analog converter to decompose the signal, filter out high-frequency noise and reconstruct the signal Extract the features from the signal; D'(t) represents the motor speed characteristic signal reconstructed by wavelet transform; j represents the number of layers of wavelet decomposition, and the value range is j=1,2,…,J, where J is the maximum number of decomposition layers; a represents the size parameter that controls the expansion and contraction of the wavelet function, a>0; b represents the translation parameter of the wavelet function on the time axis, b∈R; W j (a,b) represents the j-th wavelet coefficient, which indicates the difference between the signal and the wavelet basis function ψ at scale a and translation b. j The matching degree; Represents the mother wavelet function after scaling by a and translation by b; (4) The data solution and processing module performs fast Fourier transform on the filtered digital signal D'(t), converts the time domain signal into the frequency domain signal X(k), obtains the signal spectrum, and extracts the frequency f with the largest energy in the amplitude spectrum |X(k)| max = argmax k |X(k)| is the characteristic frequency of the motor speed; (5) The data calculation and processing module extracts the frequency f with the largest energy from the frequency domain signal X(k) max The instantaneous frequency of the corresponding motor is used to calculate the real-time speed n of the motor, where P is the number of motor pole pairs; (6) The data calculation and processing module inputs the calculated real-time motor speed n to the unmanned vehicle overspeed monitoring and control module, and compares the real-time speed n with the safety threshold n. th Determine whether it is overspeeding, and in the case of overspeed, according to the speed deviation Δn=nn th Calculate the braking torque T = K p ·Δn+K i ∫Δndt, brake control is performed; if the brake fails, the power emergency cut-off system is triggered; the process of the brake control is: (6.1) The speed monitoring unit receives the instantaneous frequency of the motor from the speed sensing module and transmits the real-time speed of the unmanned vehicle to the visualization interface through the communication interface; (6.2) The speed monitoring unit calculates the vehicle speed based on the motor speed n and the wheel radius r By v min ≤v≤v max Determine whether the real-time speed of the unmanned vehicle is within the speed design range; at the same time, adjust the speed design range according to the environmental perception data; (6.3) If it is detected that v>v max , it indicates that the vehicle speed exceeds the design speed range of the unmanned vehicle, and the speed monitoring unit generates an overspeed signal S over =1 and sent to the brake system control unit, triggering the emergency braking procedure and controlling the brake pressure Increment and start timer T; (6.4) The brake system control unit monitors the brake system's response time t through a timer brake , if t brake >t max , the backup braking mechanism is triggered and the power emergency cut-off system is activated to reduce the vehicle speed to a safe range within a preset time; (6.5) If the unmanned vehicle decelerates to a safe zone within the preset time, the braking system control unit sends a signal to the visual interface, and the visual interface shows that the vehicle resumes normal driving; (6.6) If the vehicle speed does not drop to the safe range within the preset time, the brake system control unit sends a signal to the power emergency cut-off system control unit to trigger the power emergency cut-off; (6.7) After receiving the signal, the power emergency cut-off system control unit sends a power cut-off command to the power emergency cut-off device; the power emergency cut-off device cuts off the power supply, causing the unmanned vehicle to slow down to a stop; (6.8) After cutting off the power supply, the power emergency cut-off device sends a signal to the visual interface, which notifies the user that the vehicle has entered the emergency braking state.

2. The unmanned vehicle overspeed detection and brake failure emergency braking method according to claim 1 is characterized in that: In step (1), when the motor rotor rotates, the change in magnetic field strength causes the Hall voltage V H The periodic change of the Hall voltage V H : Where I is the current passing through the linear Hall sensor; B is the magnetic induction intensity of the external magnetic field; R H is the Hall coefficient; d is the material thickness.

3. The unmanned vehicle overspeed detection and brake failure emergency braking method according to claim 1 is characterized in that: In step (2), the periodic voltage signal output by the linear Hall sensor is input into the amplification filter circuit, and an operational amplifier is used to form a common-phase or inverting amplification circuit with an amplification factor of A. v for: R f is the feedback resistor, R in is the input resistance.

4. The unmanned vehicle overspeed detection and brake failure emergency braking method according to claim 1, characterized in that: In step (2), by adjusting the feedback resistor R f and input resistance R in The resistance value increases the amplitude of the periodic voltage signal and adjusts the Hall voltage V H The amplitude range is , and an RC low-pass filter is used to filter out noise.

5. The unmanned vehicle overspeed detection and brake failure emergency braking method according to claim 1, characterized in that: In step (2), the high-frequency noise is filtered out and the periodic voltage signal is retained by adjusting the cut-off frequency of the noise. The cut-off frequency of the noise is f c for: Among them, R is the resistance and C is the capacitance.

6. The unmanned vehicle overspeed detection and brake failure emergency braking method according to claim 1, characterized in that: In step (3), the data calculation and processing module performs wavelet transform on the digital signal D(t) converted by the digital-to-analog converter, and uses the formula Decompose the signal; where W(a,b) represents the matching degree of the signal D(t) with the wavelet basis function ψ at scale a and translation b; a represents the size parameter that controls the degree of expansion and contraction of the wavelet function, a>0; b represents the translation parameter that controls the position of the wavelet function on the time axis, b∈R; D(t) represents the input signal, which represents the original voltage signal of the Hall sensor; t represents the time variable, Represents the mother wavelet function ψ(t) after scaling and translation.

7. The unmanned vehicle overspeed detection and brake failure emergency braking method according to claim 1, characterized in that: In step (4), the data solution and processing module performs fast Fourier transform on the filtered digital signal D'(t), and uses the formula Convert the time domain signal into the frequency domain signal X(t) to obtain the spectrum of the signal.

8. The unmanned vehicle overspeed detection and brake failure emergency braking method according to claim 1, characterized in that: In step (5), the data solution and processing module extracts the frequency f with the maximum energy from the frequency domain signal X(k) max is the instantaneous frequency of the corresponding motor, through The real-time speed n of the motor is calculated, where P is the number of motor pole pairs.

9. The unmanned vehicle overspeed detection and brake failure emergency braking method according to claim 1, characterized in that: In step (6.8), after the power supply is cut off, the power supply emergency cut-off device sends a signal to the visual interface, and the interface displays "Vehicle failure, power supply has been cut off", notifying the user that the vehicle has entered the emergency braking state.

10. An emergency braking system for implementing the unmanned vehicle overspeed detection and brake failure emergency braking method as claimed in claim 1, characterized in that: It includes a speed sensing module, an unmanned vehicle overspeed monitoring and control module, and a power emergency cut-off device; The speed sensing module includes a linear Hall sensor, a magnetic sensor, an amplifying and filtering circuit, a digital-to-analog converter and a data solving and processing module; the linear Hall sensor collects the magnetic field changes generated by the rotation of the wheel motor rotor through the magnetic sensor, converts the mechanical rotation into a magnetic signal, and converts the magnetic signal into a periodic voltage signal for output; the digital-to-analog converter converts the filtered analog voltage signal into a digital signal, and outputs the digital signal to the data solving and processing module; The unmanned vehicle overspeed monitoring and control module includes a speed monitoring unit, a braking system control unit, a communication module, a power emergency cut-off system control unit and a visualization interface; the speed monitoring unit receives the instantaneous frequency of the motor provided by the speed sensing module, and transmits the real-time speed of the unmanned vehicle to the visualization interface through the communication module; when the power emergency cut-off device receives the power cut-off signal issued by the unmanned vehicle overspeed monitoring and control module, it cuts off the power supply.

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