Rear-mounted automatic emergency braking system and method

Abstract

The invention relates to the field of vehicle braking, in particular to a rear-mounted automatic emergency braking system and method.A braking decision module detects the relative distance between a vehicle and a front-end obstacle and calculates braking information according to the relative distance, and the braking information comprises the tensioning stroke and the tensioning speed of a brake pedal; brake information is transmitted to the stay wire driving mechanism through a communication network in the system, and the stay wire driving mechanism drives the stay wire to pull the brake pedal according to the brake information. The automatic braking depth and speed are controlled, the smoothness of automatic braking control is improved, CAN communication of the automobile is not needed, and normal running of the automobile is prevented from being affected.

Description

Technical Field

[0001] The present invention relates to the field of vehicle braking, and in particular to a post-installed automatic emergency braking system and method. Background Art

[0002] Traditional vehicle braking systems mainly rely on the driver's operational response, but in an emergency, the driver may cause a collision accident due to untimely response or improper operation. In order to improve driving safety, the automatic emergency braking system (AEB) came into being.

[0003] For old models, an automatic emergency braking system needs to be retrofitted to achieve the automatic emergency braking function. The patent application with publication number CN213862198U discloses a wire-type automatic driving wire control braking system. After receiving the ECU brake signal, the push rod motor pulls the brake cable, and the brake cable is connected to the brake pedal to brake the vehicle. However, this control braking system does not have the function of controlling the braking depth, which affects the smoothness of the braking control, and requires CAN communication with the car, which poses a risk of affecting the normal operation of the car. Summary of the invention

[0004] To solve the above problems, the present invention provides a post-installed automatic emergency braking system and method, which can realize the control of automatic braking depth and speed, improve the smoothness of automatic braking control, and do not require the car to perform CAN communication, so as to avoid affecting the normal driving of the car.

[0005] In a first aspect, the technical solution of the present invention provides a post-installed automatic emergency braking system, including a cable, a cable drive mechanism, and a brake decision module; One end of the pull wire is connected to the brake pedal, and the other end is connected to the pull wire drive mechanism; the pull wire drive mechanism is electrically connected to the brake decision module; The braking decision module detects the relative distance between the vehicle and the front obstacle, and calculates braking information based on the relative distance. The braking information includes the brake pedal tensioning stroke and tensioning speed. The braking information is transmitted to the cable drive mechanism through the system's internal communication network. The cable drive mechanism drives the cable to pull the brake pedal according to the braking information.

[0006] In an optional embodiment, the wire-pulling drive mechanism includes a motor, a gear, a wire wheel, an encoder, and a motor control module; The gear fixing sleeve is passed on the output shaft of the motor, the center sleeve of the wire wheel is passed on the gear and meshes with the gear, one end of the pulling wire is fixed on the wire wheel, and the rest is wound in the inner groove of the outer wall of the cable; the encoder is electrically connected to the motor control module, the motor control module is electrically connected to the brake decision module, and the wire wheel rotation information is collected through the encoder.

[0007] In an optional embodiment, the wire drive mechanism also includes an upper shell, a lower shell, a circuit board and a connector. The lower shell is connected to the motor, and the wire wheel and the circuit board are located in the lower shell. The lower shell has a through hole for the wire to extend out, and the connector is arranged on the lower shell; the upper shell is connected to the lower shell; the motor control module is arranged on the circuit board, and the motor control module is electrically connected to the connector, and communicates with the brake decision module and the motor through the connector.

[0008] In an optional embodiment, the encoder is a magnetic encoder, the magnet of the magnetic encoder is arranged at the center of the wire wheel, and the magnetic chip of the magnetic encoder is arranged on the circuit board.

[0009] In an optional embodiment, the motor control module includes an MCU controller and a bipolar mode H-bridge drive circuit. The MCU controller receives the braking information transmitted by the braking decision module and controls the motor action through the H-bridge drive circuit.

[0010] In a second aspect, the technical solution of the present invention provides a post-installed automatic emergency braking method, comprising the following steps: The braking decision module detects the relative distance between the vehicle and the front obstacle; Calculating braking information according to the relative distance, the braking information including brake pedal tightening stroke and tightening speed; Transmitting brake information to the cable drive mechanism via the internal communication network of the automatic emergency brake system; The cable driving mechanism drives the cable to pull the brake pedal according to the brake information; one end of the cable is connected to the brake pedal, and the other end is connected to the cable driving mechanism.

[0011] In an optional implementation, the braking decision module detects the relative distance between the vehicle and the front obstacle, specifically including: Step 1: At the first moment, the millimeter wave radar emits a millimeter wave of a fixed speed, and the relative distance S1 between the vehicle and the front obstacle at the first moment is calculated by the following formula: S1=(v*t1) / 2; Where v is the velocity of the millimeter wave emitted by the millimeter wave radar, and t1 is the time between the first moment and the moment when the reflected millimeter wave is received; Step 2: At an interval of t from the first moment d At the second moment of the duration, the millimeter-wave radar emits a millimeter wave of a fixed speed, and the relative distance S2 between the vehicle and the front obstacle at the second moment is calculated by the following formula: S2=(v*t2) / 2; Wherein, t1 is the duration between the second moment and the moment when the reflected millimeter wave is received.

[0012] In an optional implementation, calculating the braking information according to the relative distance specifically includes: Step 1: Calculate the relative speed Δv between the vehicle and the obstacle ahead using the following formula: Δv=(S1-S2) / t d ; Step 2: Calculate the pre-collision time t by the following formula: y , t y =S2 / Δv; Step 3: Determine the pre-collision time t y Whether it is greater than a first preset time threshold or less than 0; Step 4: If yes, set the brake pedal tensioning stroke to 0 and the tensioning speed to 0; Step 5: If not, determine the pre-collision time t y whether it is less than a second preset time threshold, the second preset time threshold being less than the first preset time threshold; Step 6: If yes, set the brake pedal tensioning stroke to the maximum brake pedal stroke and the tensioning speed to the preset speed value; Step 7, if not, calculate the brake pedal tensioning stroke and tensioning speed using the following formula: Brake pedal tension travel = brake pedal maximum travel + (pre-collision time - second preset time threshold) * a; Tightening speed = brake pedal tightening travel / b; Wherein, a=-maximum travel of the brake pedal / (first preset time threshold-second preset time threshold), b=maximum travel of the brake pedal / preset speed value.

[0013] In an optional embodiment, the cable driving mechanism drives the cable to pull the brake pedal according to the brake information, specifically comprising: Step 1, real-time collection of wire displacement distance; Step 2, determining whether the cable displacement distance satisfies the brake pedal tensioning travel; Step 3, if yes, stop controlling the pull line; Step 4, if not, calculate the actual motor rotation speed v0 by the following formula, v0=L / t0; Where, L is the displacement distance of the pull wire collected at each time t0; the pull wire driving mechanism drives the pull wire through the motor; Step 5, calculating the difference between the actual rotation speed v0 and the tensioning speed; Step 6, determine the relationship between the difference and the difference threshold. If the difference is greater than the first difference threshold, the output voltage of the motor control module is controlled to increase or decrease by a first percentage of the maximum output voltage. If the difference is between the first difference threshold and the second difference threshold, the output voltage of the motor control module is controlled to increase or decrease by a second percentage of the maximum output voltage. If the difference is between the second difference threshold and the third difference threshold, the output voltage of the motor control module is controlled to increase or decrease by a third percentage of the maximum output voltage. During this period, the first difference threshold is greater than the second difference threshold, the second difference threshold is greater than the third difference threshold, the first percentage is greater than the second percentage, and the second percentage is greater than the third percentage.

[0014] In an optional embodiment, the wire driving mechanism uses a speed and position dual-loop PID control method to control the motor to drive the wire, with the position loop as the outer loop, the speed loop as the inner loop, and the output value of the outer loop as the target value of the inner loop.

[0015] The present invention provides a post-installed automatic emergency braking system and method, which have the following beneficial effects compared to the prior art: a braking decision module detects vehicle-related information, and calculates braking information including brake pedal tensioning stroke and tensioning speed based on the vehicle-related information, and then sends the braking information to a cable drive mechanism, so that the cable drive mechanism can use the braking information to perform cable control, thereby achieving control of automatic braking depth and speed, improving the smoothness of automatic braking control, and eliminating the need for CAN communication of the vehicle to avoid affecting the normal driving of the vehicle. BRIEF DESCRIPTION OF THE DRAWINGS In order to more clearly illustrate the embodiments of the present invention or the technical solutions of the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0016] Figure 1 It is a schematic block diagram of the structural principle of a post-installed automatic emergency braking system provided by an embodiment of the invention.

[0017] Figure 2 It is a schematic diagram of the exploded structure of the wire drive mechanism.

[0018] Figure 3 It is a schematic diagram of the assembly structure of the wire drive mechanism.

[0019] Figure 4 It is a schematic diagram of the principle structure of the motor control module.

[0020] Figure 5It is a schematic flow chart of a post-installed automatic emergency braking method provided by an embodiment of the present invention.

[0021] Figure 6 This is a schematic diagram of PID control.

[0022] In the figure, 1-upper shell, 2-circuit board, 3-lower shell, 4-reel, 5-gear, 6-motor, 7-connector, 8-magnet, 9-pull wire. DETAILED DESCRIPTION

[0023] In order to enable those skilled in the art to better understand the scheme of the present invention, the present invention is further described in detail below in conjunction with the accompanying drawings and specific implementation methods. Obviously, the described embodiments are only part of the embodiments of the present invention, rather than all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention.

[0024] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as those commonly understood by those skilled in the art of the present invention. The terms used in the specification of the present invention herein are only for the purpose of describing specific embodiments and are not intended to limit the present invention.

[0025] Figure 1 It is a schematic block diagram of the structural principle of a post-installed automatic emergency braking system provided by an embodiment of the invention. The system includes a cable, a cable drive mechanism and a brake decision module.

[0026] One end of the cable is connected to the brake pedal, and the other end is connected to the cable drive mechanism; the cable drive mechanism is electrically connected to the brake decision module. The brake decision module detects the relative distance between the vehicle and the front obstacle, calculates the braking information based on the relative distance, and the braking information includes the brake pedal tensioning stroke and tensioning speed, and transmits the braking information to the cable drive mechanism through the system's internal communication network. The cable drive mechanism drives the cable to pull the brake pedal according to the braking information.

[0027] In an optional implementation, the braking decision module detects the relative distance between the vehicle and the front obstacle through radar. It should be noted that the braking decision module is a module independent of the functional modules in the car itself. The braking decision module is a part of the automatic emergency braking system installed after this embodiment. It communicates with the cable drive mechanism through an internal communication network, such as a CAN line, and does not need to communicate with the car body to avoid affecting the normal operation of the car.

[0028] Figure 2 It is a schematic diagram of the decomposed structure of the wire drive mechanism. Figure 3 It is a schematic diagram of the assembly structure of the wire drive mechanism, such as Figure 2 and3 As shown, the wire-pulling drive mechanism of this embodiment includes a motor 6 , a gear 5 , a wire wheel 4 , an encoder, a motor control module, an upper shell 1 , a lower shell 3 , a circuit board 2 and a connector 7 .

[0029] The gear 5 is fixedly sleeved on the output shaft of the motor 6, and the center sleeve of the wire wheel 4 is sleeved on the gear 5 and meshed with the gear 5. The gear 5 can be an octagonal gear 5. One end of the pull wire 9 is fixed on the wire wheel 4, and the rest is wound in the inner groove of the outer wall of the cable. In an optional embodiment, the pull wire 9 is a steel wire rope. The lower shell 3 is connected to the motor 6, and the wire wheel 4 and the circuit board 2 are located in the lower shell 3. The lower shell 3 has a through hole for the pull wire 9 to extend out, and the connector 7 is arranged on the lower shell 3; the upper shell 1 is connected to the lower shell 3; the motor control module is arranged on the circuit board 2, and the motor control module is electrically connected to the connector 7, and communicates with the brake decision module and the motor 6 through the connector 7.

[0030] The encoder is electrically connected to the motor control module, which is electrically connected to the brake decision module, and the encoder collects the rotation information of the wire wheel 4, so as to obtain the displacement of the wire 9 through the rotation information of the wire wheel 4 and then control the automatic braking process. In this embodiment, the encoder is a magnetic encoder, the magnet 8 of the magnetic encoder is set at the center of the wire wheel 4, and the magnetic chip of the magnetic encoder is set on the circuit board 2.

[0031] Figure 4 It is a schematic diagram of the principle structure of the motor control module. In this embodiment, the motor control module includes an MCU controller and a bipolar mode H-bridge drive circuit. The MCU controller receives the brake information transmitted by the brake decision module and controls the action of the motor 6 through the H-bridge drive circuit. The H-bridge drive circuit has the advantages of being able to run forward and reverse, fast startup, high speed regulation accuracy, and good dynamic performance. When the motor 6 needs to rotate forward, the MCU controls Q1 and Q4 to turn on the MOS tubes, and Q2 and Q3 to turn off the MOS tubes; when the motor 6 is reversed, the MCU controls Q2 and Q3 to turn on the MOS tubes, and Q1 and Q4 to turn off the MOS tubes; when the motor 6 needs to stop, the MCU prohibits the output of Q1, Q2, Q3, and Q4.

[0032] In this embodiment, after the motor control module receives the action instruction through the connector 7, it collects the single-turn absolute encoder value through the magnet 8 and the magnetic chip in the circuit board 2 to determine whether the action instruction is met. If not, the motor control module controls the motor 6 to rotate through the connector 7, and the motor 6 drives the wire wheel 4 to rotate through the octagonal gear 5. The wire wheel 4 rotates to drive the wire rope to move, and finally pulls the brake pedal. The single-turn absolute encoder value is monitored in real time during the whole process. When the action instruction is met and the set brake pedal position is reached, the motor control module controls the motor 6 to stop rotating through the connector 7, thereby stopping the entire wire driving mechanism.

[0033] In order to adapt to all vehicle models, this system also has a self-learning function. After the brake decision module sends a self-learning instruction to the motor 6 control unit, the motor control module starts the self-learning function: the motor control module controls the motor 6 to rotate in the direction of the foot brake release. After rotating to the maximum operable position, the motor 6 reverses and rotates in the direction of tightening the foot brake at a low speed, and detects the tension of the motor 6 in real time; when it begins to detect that the motor 6 is subjected to a tension greater than the idling of the motor 6, the motor control module records the position of the motor 6 cable 9 at this time, marking it as the zero point of the brake pedal stroke, and the motor 6 continues to pull the foot brake pedal through the cable 9. When it is detected that the foot brake pedal can no longer be pulled, the motor control module records the position of the motor 6 cable 9 at this time, marking it as the maximum travel point of the brake pedal stroke. Finally, the zero point and the maximum travel point of the brake pedal stroke are fed back to the brake decision module to complete the entire self-learning process.

[0034] An embodiment of a retrofitted automatic emergency braking system is described in detail above. Based on the retrofitted automatic emergency braking system described in the above embodiment, an embodiment of the present invention further provides a retrofitted automatic emergency braking method corresponding to the system.

[0035] Figure 5 This is a flowchart of a post-installed automatic emergency braking method provided by an embodiment of the present invention. According to different requirements, the order of the steps in the flowchart can be changed, and some can be omitted.

[0036] like Figure 5 As shown, the method includes the following steps.

[0037] S1, the braking decision module detects the relative distance between the vehicle and the front obstacle.

[0038] S2, calculating braking information according to the relative distance, the braking information including the brake pedal tensioning stroke and tensioning speed.

[0039] S3, transmits the braking information to the cable drive mechanism through the internal communication network of the automatic emergency braking system.

[0040] S4, the cable driving mechanism drives the cable 9 to pull the brake pedal according to the brake information.

[0041] In this embodiment, the braking decision module first detects the relative distance between the vehicle and the front obstacle, and then derives the braking information based on the relative distance. The braking information includes the brake pedal tensioning stroke and tensioning speed. The braking information is then transmitted to the cable drive mechanism by the internal communication network of the automatic emergency braking system. The cable drive mechanism drives the cable 9 to pull the brake pedal according to the braking information, thereby achieving the purpose of controlling the braking depth and speed based on actual conditions, ensuring the smoothness of braking, and at the same time, there is no need to communicate with the car and does not affect the normal operation of the car.

[0042] In this embodiment, the braking decision module detects the relative distance between the vehicle and the front obstacle through radar, which specifically includes the following steps.

[0043] Step 1: At the first moment, the millimeter wave radar emits a millimeter wave of a fixed speed, and the relative distance S1 between the vehicle and the front obstacle at the first moment is calculated by the following formula: S1=(v*t1) / 2; Where v is the velocity of the millimeter wave emitted by the millimeter wave radar, and t1 is the duration between the first moment and the moment when the reflected millimeter wave is received.

[0044] Step 2: At an interval of t from the first moment d At the second moment of the duration, the millimeter-wave radar emits a millimeter wave of a fixed speed, and the relative distance S2 between the vehicle and the front obstacle at the second moment is calculated by the following formula: S2=(v*t2) / 2; Wherein, t1 is the duration between the second moment and the moment when the reflected millimeter wave is received.

[0045] The millimeter wave is emitted at the first moment and the second moment respectively. After the first moment t d The time is the second moment, which is much lower than the current moment, and the first moment is equivalent to t before the current moment. d moment.

[0046] This embodiment calculates the braking information by detecting the relative distance at two moments, which specifically includes the following steps.

[0047] Step 1: Calculate the relative speed Δv between the vehicle and the obstacle ahead using the following formula: Δv=(S1-S2) / t d .

[0048] Step 2: Calculate the pre-collision time t by the following formula: y , t y =S2 / Δv.

[0049] Step 3: Determine the pre-collision time t y Whether it is greater than the first preset time threshold or less than 0.

[0050] Step 4: If yes, set the brake pedal tensioning stroke to 0 and the tensioning speed to 0.

[0051] Step 5: If not, determine the pre-collision time t y Whether it is less than a second preset time threshold, the second preset time threshold is less than the first preset time threshold.

[0052] Step 6: If yes, set the brake pedal tensioning stroke to the maximum brake pedal stroke and the tensioning speed to the preset speed value.

[0053] Step 7, if not, calculate the brake pedal tensioning stroke and tensioning speed using the following formula: Brake pedal tension travel = brake pedal maximum travel + (pre-collision time - second preset time threshold) * a; Braking speed = brake pedal braking distance / b.

[0054] Wherein, a=-maximum travel of the brake pedal / (first preset time threshold-second preset time threshold), b=maximum travel of the brake pedal / preset speed value.

[0055] In an optional embodiment, the first preset time threshold is 1 second, and the second preset time threshold is 2.5 seconds. The brake depth is determined according to the pre-collision time. When the pre-collision time is less than 1 second, the pedal depth instruction is the maximum stroke of the brake pedal, and the tightening speed is 613 cm / s of the motor; when the pre-collision time is greater than 2.5 seconds or less than 0 seconds, the pedal depth is 0, the brake pedal is completely released, and the tightening speed is 0; when the pre-collision time is between 1 second and 2.5 seconds, the pre-collision time is linearly related to the brake pedal stroke, and the formula is as follows: Brake pedal tension travel = brake pedal maximum travel + (pre-collision time - 1) * a; a=-brake pedal maximum travel / (2.5-1); Braking speed = brake pedal braking distance / b; b = maximum brake pedal travel / 13.

[0056] The cable driving mechanism receives the braking information from the braking decision module, and drives the cable 9 through its motor 6 based on the braking information. At the same time, the cable driving mechanism collects and controls the displacement distance of the cable 9 in real time to control the state of the cable 9, which specifically includes the following steps.

[0057] Step 1: collect the displacement distance of the pull wire 9 in real time.

[0058] Step 2, determine whether the displacement distance of the cable 9 satisfies the brake pedal tensioning stroke.

[0059] Step 3: If yes, stop controlling the pull wire 9.

[0060] Step 4, if not, calculate the actual rotation speed v0 of the motor 6 by the following formula: v0=L / t0.

[0061] Wherein, L is the displacement distance of the pull wire 9 collected at each time t0; the pull wire driving mechanism drives the pull wire 9 through the motor 6.

[0062] Step 5, calculate the difference between the actual rotation speed v0 and the tensioning speed.

[0063] Step 6, determine the relationship between the difference and the difference threshold. If the difference is greater than the first difference threshold, the output voltage of the motor control module is controlled to increase or decrease by a first percentage of the maximum output voltage. If the difference is between the first difference threshold and the second difference threshold, the output voltage of the motor control module is controlled to increase or decrease by a second percentage of the maximum output voltage. If the difference is between the second difference threshold and the third difference threshold, the output voltage of the motor control module is controlled to increase or decrease by a third percentage of the maximum output voltage. During this period, the first difference threshold is greater than the second difference threshold, the second difference threshold is greater than the third difference threshold, the first percentage is greater than the second percentage, and the second percentage is greater than the third percentage.

[0064] In an optional embodiment, if the difference is greater than 5 cm / s, the output voltage of the motor control module increases or decreases at 20 percent of the maximum output voltage; if the difference is greater than 1 cm / s and less than or equal to 5 ms / s, the output voltage of the motor control module increases or decreases at 10 percent of the maximum output voltage; if the difference is greater than 0.2 cm / s and less than or equal to 1 ms / s, the output voltage of the motor control module increases or decreases at 5 percent of the maximum output voltage.

[0065] The voltage output by the motor control module (to make the tensioning speed of the motor 6 reach the set tensioning speed) and the real-time position of the motor 6 (to control the motor 6 to stop when reaching the set position) form a closed-loop control.

[0066] In this embodiment, the wire driving mechanism uses a speed and position dual-loop PID control method to control the motor 6 to drive the wire 9, with the position loop as the outer loop and the speed loop as the inner loop, and the output value of the outer loop as the target value of the inner loop.

[0067] Figure 6 This is a schematic diagram of PID control. According to the PID formula, when the position target is closer, the outer loop error becomes smaller and smaller, so that the output inner loop target value becomes smaller and smaller. Therefore, the final effect is that the closer to the target value, the smaller the speed.

[0068] After receiving the target position and target speed, the motor control module outputs PWM to control the motor 6 to pull the cable 9 through the position loop control and the speed loop control, and controls the movement of the foot brake pedal. During the pulling process, the position and speed of the cable 9 are obtained by fixing the cable 9 on the installed wire wheel 4 and collecting the single-turn absolute encoder value, so as to accurately obtain the position of the cable 9 in real time. At the same time, the current movement speed of the cable 9 is calculated by calculating the change value of the position per unit time.

[0069] In an optional embodiment, during the process of controlling the motor 6, the position information is fed back to the upper-level braking decision module. If the position and speed information input to the braking decision module remains unchanged, the position loop and speed loop control system are used to control the motor 6 to tighten the foot brake pedal to the target position at a fixed speed; if the position and speed information input to the braking decision module changes, the motor 6 is controlled according to the latest input parameters to control the foot brake pedal to act according to the input parameters.

[0070] The above disclosure is only a preferred embodiment of the present invention, but the present invention is not limited thereto. Any non-creative changes that can be thought of by a person skilled in the art, as well as several improvements and modifications made without departing from the principle of the present invention, should fall within the protection scope of the present invention.

Claims

1. A post-installed automatic emergency braking system, characterized in that: It includes a cable, a cable driving mechanism and a brake decision module; One end of the pull wire is connected to the brake pedal, and the other end is connected to the pull wire drive mechanism; the pull wire drive mechanism is electrically connected to the brake decision module; The braking decision module detects the relative distance between the vehicle and the front obstacle, and calculates braking information based on the relative distance. The braking information includes the brake pedal tensioning stroke and tensioning speed. The braking information is transmitted to the cable drive mechanism through the system's internal communication network. The cable drive mechanism drives the cable to pull the brake pedal according to the braking information.

2. The post-installed automatic emergency braking system according to claim 1, characterized in that: The wire-pulling drive mechanism includes a motor, a gear, a wire wheel, an encoder and a motor control module; The gear fixing sleeve is passed on the output shaft of the motor, the center sleeve of the wire wheel is passed on the gear and meshes with the gear, one end of the pulling wire is fixed on the wire wheel, and the rest is wound in the inner groove of the outer wall of the cable; the encoder is electrically connected to the motor control module, the motor control module is electrically connected to the brake decision module, and the wire wheel rotation information is collected through the encoder.

3. The post-installed automatic emergency braking system according to claim 2, characterized in that: The wire driving mechanism also includes an upper shell, a lower shell, a circuit board and a connector. The lower shell is connected to the motor, and the wire wheel and the circuit board are located in the lower shell. The lower shell has a through hole for the wire to extend out, and the connector is arranged on the lower shell; the upper shell is connected to the lower shell; the motor control module is arranged on the circuit board, and the motor control module is electrically connected to the connector, and communicates with the brake decision module and the motor through the connector.

4. The post-installed automatic emergency braking system according to claim 3, characterized in that: The encoder is a magnetic encoder, the magnet of the magnetic encoder is arranged at the center of the wire wheel, and the magnetic chip of the magnetic encoder is arranged on the circuit board.

5. The post-installed automatic emergency braking system according to any one of claims 2 to 4, characterized in that: The motor control module includes an MCU controller and a bipolar mode H-bridge drive circuit. The MCU controller receives the brake information transmitted by the brake decision module and controls the motor action through the H-bridge drive circuit.

6. A post-installed automatic emergency braking method, characterized in that: The following steps are involved: The braking decision module detects the relative distance between the vehicle and the front obstacle; Calculating braking information according to the relative distance, the braking information including brake pedal tightening stroke and tightening speed; Transmitting brake information to the cable drive mechanism via the internal communication network of the automatic emergency brake system; The cable driving mechanism drives the cable to pull the brake pedal according to the brake information; one end of the cable is connected to the brake pedal, and the other end is connected to the cable driving mechanism.

7. The post-installed automatic emergency braking method according to claim 6, characterized in that: The braking decision module detects the relative distance between the vehicle and the front obstacle, including: Step 1: At the first moment, the millimeter wave radar emits a millimeter wave of a fixed speed, and the relative distance S1 between the vehicle and the front obstacle at the first moment is calculated by the following formula: S1=(v*t1) / 2; Where v is the velocity of the millimeter wave emitted by the millimeter wave radar, and t1 is the time between the first moment and the moment when the reflected millimeter wave is received; Step 2: At an interval of t from the first moment d At the second moment of the duration, the millimeter-wave radar emits a millimeter wave of a fixed speed, and the relative distance S2 between the vehicle and the front obstacle at the second moment is calculated by the following formula: S2=(v*t2) / 2; Wherein, t1 is the duration between the second moment and the moment when the reflected millimeter wave is received.

8. The post-installed automatic emergency braking method according to claim 7, characterized in that: Calculating braking information according to the relative distance specifically includes: Step 1: Calculate the relative speed Δv between the vehicle and the obstacle ahead using the following formula: Δv=(S1-S2) / t d ; Step 2: Calculate the pre-collision time t by the following formula: y , t y =S2 / Δv; Step 3: Determine the pre-collision time t y Whether it is greater than a first preset time threshold or less than 0; Step 4: If yes, set the brake pedal tensioning stroke to 0 and the tensioning speed to 0; Step 5: If not, determine the pre-collision time t y whether it is less than a second preset time threshold, the second preset time threshold being less than the first preset time threshold; Step 6: If yes, set the brake pedal tensioning stroke to the maximum brake pedal stroke and the tensioning speed to the preset speed value; Step 7, if not, calculate the brake pedal tensioning stroke and tensioning speed using the following formula: Brake pedal tension travel = brake pedal maximum travel + (pre-collision time - second preset time threshold) * a; Tightening speed = brake pedal tightening travel / b; Wherein, a=-maximum travel of the brake pedal / (first preset time threshold-second preset time threshold), b=maximum travel of the brake pedal / preset speed value.

9. The post-installed automatic emergency braking method according to any one of claims 6 to 8, characterized in that: The cable drive mechanism drives the cable to pull the brake pedal according to the brake information, which specifically includes: Step 1, real-time collection of wire displacement distance; Step 2, determining whether the cable displacement distance satisfies the brake pedal tensioning travel; Step 3, if yes, stop controlling the pull line; Step 4, if not, calculate the actual motor rotation speed v0 by the following formula, v0=L / t0; Where, L is the displacement distance of the pull wire collected at each time t0; the pull wire driving mechanism drives the pull wire through the motor; Step 5, calculating the difference between the actual rotation speed v0 and the tensioning speed; Step 6, determine the relationship between the difference and the difference threshold. If the difference is greater than the first difference threshold, the output voltage of the motor control module is controlled to increase or decrease by a first percentage of the maximum output voltage. If the difference is between the first difference threshold and the second difference threshold, the output voltage of the motor control module is controlled to increase or decrease by a second percentage of the maximum output voltage. If the difference is between the second difference threshold and the third difference threshold, the output voltage of the motor control module is controlled to increase or decrease by a third percentage of the maximum output voltage. During this period, the first difference threshold is greater than the second difference threshold, the second difference threshold is greater than the third difference threshold, the first percentage is greater than the second percentage, and the second percentage is greater than the third percentage.

10. The post-installed automatic emergency braking method according to claim 9, characterized in that: The wire-pulling drive mechanism uses a speed and position dual-loop PID control method to control the motor to drive the wire. The position loop serves as the outer loop, the speed loop serves as the inner loop, and the output value of the outer loop serves as the target value of the inner loop.

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