Electromagnetic auxiliary brake system based on closed-loop control and control method thereof

Abstract

With the popularity of electric bicycles in urban non-motorized transportation, traffic accidents caused by improper speed control and lack of advanced AEB system (Autonomous Emergency Braking) have become one of the obstacles to the promotion of electric bicycles. The present application provides an electromagnetic auxiliary brake system based on closed-loop control. The system introduces a new type of eddy current retarder on the basis of the original hardware structure, and carries a new speed control module with embedded system as the control center. After hardware selection and algorithm design, a mathematical model suitable for auxiliary hardware is constructed to realize closed-loop control of intelligent speed regulation. The model is simulated in the simulink / matlab environment, multiple influence factors are introduced, and the system function and stability are tested through error analysis. The electromagnetic auxiliary brake equipment and system based on closed-loop control can help reduce the risk of riding for users, promote low-carbon travel, and promote the healthy development of the electric bicycle industry.

Description

Technical Field

[0001] This invention relates to the field of electric vehicle braking technology, and more particularly to an electromagnetic auxiliary braking system based on closed-loop control and its control method, as well as a vehicle containing the electromagnetic auxiliary braking system. Background Technology

[0002] With the increasing popularity and use of electric bicycles, their safety issues have become increasingly prominent. The new national standard stipulates a maximum speed of 25 km / h, but the lack of a mature and advanced speed control system makes it difficult to ensure that the speed is limited within a reasonable range. Meanwhile, the existence of automatic braking equipment is crucial for improving the safety of electric bicycles. Therefore, how to implement intelligent speed control and emergency braking has become key to solving the "driving safety problem" of electric bicycles.

[0003] Regarding "speed control," the speed control system for electric bicycles has gone through three main stages. Initially, electric bicycle speed control was achieved by potentiometers. However, due to excessive energy consumption caused by resistance, thyristors were used for speed control, which resulted in low efficiency and high cost. These problems were not solved until the adoption of DC motors, which are still used as the power source for electric bicycles today.

[0004] Currently, permanent magnet brushless DC motors are the mainstream power equipment for electric vehicles on the market. However, existing speed control devices for electric bicycles are difficult to achieve "intelligent speed control," and scholars at home and abroad have successively carried out research on "intelligent speed control" for two-wheeled vehicles.

[0005] Wang Lei (Wang Lei. Design and Implementation of Electric Bicycle Controller Based on STM8S903K3 [D]. Nanjing University of Science and Technology, 2014) proposed that when the motor speed exceeds the reference speed, the braking torque is generated by the brushless DC motor inverter and the battery is charged at the same time. However, this method causes great damage to the battery and significantly reduces its service life.

[0006] Zhang Hailiang (Zhang Hailiang. Research on Brushless DC Motor Controller and Control Algorithm [D]. Hangzhou Dianzi University, 2012) proposed to use other devices equipped on the vehicle to judge the current driving situation and then control the speed in real time through PID. However, this method has high requirements for the basic components of the vehicle and is applicable to a limited number of situations.

[0007] Chang Fei (Chang Fei. Research on AEB system control strategy for electric two-wheeled vehicles [D]. Shanghai University of Engineering Science, 2021. DOI:10.27715 / d.cnki.gshgj.2021.000106) proposed to analyze the vehicle control system, establish a safe distance model for two-wheeled vehicles, and use PID fuzzy control. However, this method controls the original deceleration program and has high requirements for equipment.

[0008] Tian Zulin (Tian Zulin. Hardware Design and Control Algorithm Research of Automotive Automatic Braking System Based on AEB [D]. Yanshan University, 2021. DOI:10.27440 / d.cnki.gysdu.2021.001076) selected a millimeter-wave radar sensor, designed a target obstacle selection algorithm, and simultaneously monitored the speed in real time during the deceleration process, applied braking pre-fill, and analyzed and changed the real-time acceleration to achieve speed control. However, this method requires high equipment accuracy and has a high overall cost.

[0009] Fang Tao (Fang Tao. Research on Speed ​​Control of Autonomous Electric Vehicles Based on MPC Theory [D]. Xihua University, 2022. DOI:10.27411 / d.cnki.gscgc.2022.000386) adopted a hierarchical speed control scheme, combined with the MPC model prediction algorithm, and formulated two modes: constant speed and following speed to complete speed control, but it could not actively control the speed within a safe range.

[0010] Deva Hema, D. proposed an intelligent automatic speed control method to control the speed of a two-wheeled vehicle, replacing the existing acceleration system with an electronic acceleration system to achieve intelligent speed control. However, this method did not consider whether the introduced control system was compatible with the original hardware.

[0011] The PRSonawane team proposed a wireless speed control module that adjusts its speed in real time according to the external environment to reduce the risk of safety accidents. However, this method requires higher costs and still relies on the driver's subjective speed control.

[0012] Currently, the main braking methods of electric bicycles in China are divided into two categories: disc brakes and drum brakes.

[0013] The table below compares and contrasts the two existing braking methods, highlighting their respective characteristics and drawbacks.

[0014]

[0015] The drawbacks of both types of braking systems are quite obvious: disc brakes rely on contact friction for deceleration, resulting in significant lifespan limitations; while drum brakes, with their metal brake drums in a sealed environment, struggle to dissipate heat. However, both disc and drum brakes offer limited braking force, failing to provide adequate safety for electric bicycles in emergency situations. Regarding research on "emergency braking," Automatic Emergency Braking (AEB) has a long history. AEB is an automatic emergency braking system that automatically performs braking when the rider delays or fails to brake due to distraction, sensor failure, or panic. Although AEB is a mature technology, having been used in passenger cars for over a decade and becoming mandatory for trucks and buses in Europe, it has not yet been widely adopted in electric bicycles.

[0016] Therefore, most current research is limited to theoretical estimation of benefits, experimental verification of electric vehicle stability under AEB, and prototype system evaluation in rider trials. In the research on "automatic emergency braking" of two-wheeled vehicles in China, Zhou Weihua (Zhou Weihua. Application of low-tooth-difference reduction mechanism in electric bicycle wheel hub [J]. Metallurgical Information Guide, 2004(06):22-23) used a low-tooth-difference planetary reduction wheel in conjunction with an eccentric sleeve to achieve deceleration, but this method changes the motor structure and the scheme is relatively complex. Qin Yehai (Qin Yehai, Lü Chuang, Ren Jianxiang et al. Design of electric bicycle braking system based on microcontroller [J]. Digital Technology and Application, 2015(02):9.DOI:10.19695 / j.cnki.cn12-1369.2015.02.009) connected the microcontroller and the motor through the winding of the brushless DC motor, and the microcontroller was associated with the power supply, and then the wheel speed was controlled by the motor, but the overall real-time monitoring effect was poor and the braking could not be completed in time.

[0017] In summary, no fully developed intelligent speed control system has yet been proposed, either domestically or internationally, to address the potential speed hazards and emergency response issues associated with electric bicycles. Therefore, this invention aims to propose an electromagnetic assisted braking system based on closed-loop control. By introducing a novel speed control system and corresponding speed control equipment, a mathematical model suitable for this system is constructed. An electromagnetic braking method with long lifespan, zero pollution, non-contact operation, and forced force is selected as the control terminal to solve the aforementioned problems.

[0018] Furthermore, on the one hand, there are differences in understanding among those skilled in the art; on the other hand, the applicant studied a large number of documents and patents when making this invention, but due to space limitations, not all details and contents were listed in detail. However, this does not mean that the present invention does not possess the features of these prior art. On the contrary, the present invention already possesses all the features of the prior art, and the applicant reserves the right to add relevant prior art to the background art. Summary of the Invention

[0019] To address the shortcomings of existing technologies, this invention provides an electromagnetic assisted braking system and its control method based on closed-loop control, aiming to solve at least one or more technical problems existing in the prior art.

[0020] To achieve the above objectives, the present invention provides an electromagnetic assisted braking system based on closed-loop control, comprising:

[0021] The detection module is used to acquire vehicle speed information and / or relative distance information.

[0022] The control module is capable of generating modulation commands for driving the eddy current retarder based on speed information and / or relative distance information.

[0023] An eddy current retarder is operatively coupled to a vehicle and is capable of generating a modulated force for controlling the vehicle's speed and / or relative distance in response to modulation commands from a control module.

[0024] Preferably, generating modulation commands for driving the eddy current retarder based on speed information and / or relative distance information includes:

[0025] When the vehicle's speed exceeds a first speed threshold, a corresponding modulation current is input to the eddy current retarder based on the difference between the speed and the first speed threshold to generate an adjustable modulation force.

[0026] Preferably, generating modulation commands for driving the eddy current retarder based on speed information and / or relative distance information includes:

[0027] When the vehicle's speed is between a first speed threshold and a second speed threshold, the relative distance to the vehicle is obtained;

[0028] When the relative distance is less than or equal to the first distance threshold, a corresponding modulation current is input to the eddy current retarder based on the difference between the driving speed and the second speed threshold to generate an adjustable modulation force.

[0029] Preferably, generating modulation commands for driving the eddy current retarder based on speed information and / or relative distance information includes:

[0030] When the vehicle's speed is less than the second speed threshold, obtain the relative distance between the vehicles;

[0031] When the relative distance is less than or equal to the second distance threshold, a corresponding modulation current is input to the eddy current retarder based on the difference between the driving speed and the second speed threshold to generate an adjustable modulation force.

[0032] Preferably, the electromagnetic assisted braking system based on closed-loop control of the present invention further includes a conversion module, which is capable of converting the modulation command generated by the control module related to speed information and / or relative distance information into a modulation current and providing it to the eddy current retarder.

[0033] Preferably, the electromagnetic assisted braking system based on closed-loop control according to the present invention may further include a power supply module for providing electrical energy to the detection module and / or control module.

[0034] Preferably, the detection module in this invention may include:

[0035] Speed ​​sensor, used to acquire vehicle speed information;

[0036] The ranging module is used to obtain the relative distance information of vehicles.

[0037] The ranging module performs ranging operations in association with the speed information acquired by the speed sensor.

[0038] Preferably, the present invention also relates to a control method for an electromagnetic assisted braking system based on closed-loop control, which may include:

[0039] Acquire vehicle speed information and / or relative distance information;

[0040] Based on speed information and / or relative distance information, a modulation command is generated for driving the eddy current retarder.

[0041] The eddy current retarder responds to a modulation command by generating a modulation force for controlling the speed and / or relative distance of the vehicle.

[0042] Preferably, in this invention, the generation of modulation commands for driving the eddy current retarder based on speed information and / or relative distance information is performed by means of preset program commands based on the correlation between speed information and / or relative distance information and the change of a set threshold over time.

[0043] Preferably, the present invention also relates to an electric vehicle, which may include the aforementioned electromagnetic auxiliary braking system based on closed-loop control.

[0044] This invention provides an electromagnetic assisted braking system based on closed-loop control. Compared to previous technologies that improved the braking effect of the braking device, this invention achieves autonomous braking by adding an electric turbine retarder to the electric vehicle, assisting the manual handbrake. This significantly improves the operational error tolerance during driving, thereby reducing the accident rate and maintaining traffic safety. Furthermore, the electromagnetic assisted braking system provided by this invention not only significantly reduces traffic accidents but also increases the service life and lifespan of electric vehicles, increasing the economic benefits of two-wheeled non-motorized vehicles. This invention possesses mature and robust core technologies, uses reasonable main energy materials, and has a guaranteed energy supply, making it practically feasible from the perspective of energy utilization and energy conservation. Electric vehicles equipped with this system can significantly improve their performance, providing people with more convenient and safer services. Attached Figure Description

[0045] Figure 1 This is a circuit diagram of an electromagnetic assisted braking system according to a preferred embodiment of the present invention;

[0046] Figure 2 This is a hardware working principle diagram of an electromagnetic assisted braking system according to a preferred embodiment of the present invention;

[0047] Figure 3 This is a flowchart of a preferred embodiment of the electromagnetic assisted braking system control method provided by the present invention;

[0048] Figure 4 This is a schematic diagram of the assembly structure of an eddy current retarder according to a preferred embodiment of the present invention;

[0049] Figure 5 This is an isometric schematic diagram of an eddy current retarder according to a preferred embodiment of the present invention;

[0050] Figure 6 This is a top view of an eddy current retarder according to a preferred embodiment of the present invention;

[0051] Figure 7 This is a flowchart of a mathematical model established based on a preferred embodiment of the electromagnetic assisted braking system control method provided by the present invention.

[0052] List of reference numerals

[0053] 1: Speed ​​sensor; 2: Power supply module; 3: Distance measuring module; 4: Control module; 5: Conversion module; 6: Eddy current retarder; 61: Outer nut; 62: First inner nut; 63: Fixing bracket; 64: Stator; 65: Second inner nut; 66: Rotary drum; 67: Wheel. Detailed Implementation

[0054] The preferred embodiments of the present invention will now be described in detail with reference to the accompanying drawings, so that the advantages and features of the present invention can be more easily understood by those skilled in the art, thereby providing a clearer and more explicit definition of the scope of protection of the present invention.

[0055] See Figure 1 This invention provides an electromagnetic auxiliary braking device / system based on closed-loop control, which may include:

[0056] The detection module is used to acquire vehicle speed information and / or relative distance information.

[0057] The control module 4 is capable of generating modulation commands for driving the electric eddy current retarder 6 based on the vehicle's speed information and / or relative distance information.

[0058] The eddy current retarder 6 is capable of generating a modulating force in response to the modulation command of the control module 4 for controlling the speed and / or relative distance of the vehicle.

[0059] Optionally, the vehicle described in this invention is an electric vehicle. Specifically, the electric vehicle described in this invention can be an electric bicycle, an electric car, or an electric motorcycle, etc. Preferably, a specific example of the electric vehicle described in this invention is an electric bicycle.

[0060] Specifically, the relative distance information described in this invention can be the relative distance between an electric vehicle (such as an electric bicycle) and one or more target objects (such as target obstacles) within its direction of travel or range.

[0061] According to a preferred embodiment of the present invention, the control module 4 generates modulation commands for driving the eddy current retarder 6 based on speed information and / or relative distance information. This is done by relying on the correlation between the speed information and / or relative distance information and the change of a set threshold over time, and executing the commands through preset or custom program instructions.

[0062] Furthermore, the electromagnetic auxiliary braking device / system based on closed-loop control provided by the present invention may also include a conversion module 5. The conversion module 5 can input a modulated current for generating a modulation force to the eddy current retarder 6 based on a pulse modulation command from the control module 4. Specifically, the conversion module 5 may be a voltage-to-current module, such as a voltage-to-current transmitter.

[0063] Furthermore, the electromagnetic assisted braking system based on closed-loop control provided by the present invention may also include a power supply module 2. Specifically, the power supply module 2 can provide power to other electronic components involved in the system, such as the detection module and the control module 4.

[0064] Specifically, the electromagnetic auxiliary braking system based on closed-loop control provided by this invention can be composed of six parts: a ranging module, an STM32 microcontroller, a voltage-to-current conversion module, a mobile power supply, a speed sensor, and an eddy current retarder. The electromagnetic auxiliary braking system provided by this invention has intelligent speed control and emergency braking functions, which can significantly reduce traffic accidents caused by improper speed control of electric vehicles (such as electric bicycles).

[0065] According to a preferred embodiment, the detection module may include a velocity sensor 1 and a ranging module 3. Specifically, the velocity sensor 1 may be a Hall effect velocity sensor. The ranging module 3 may be a distance detection module based on ultrasonic principles.

[0066] It is understood that the Hall speed sensor and ultrasonic ranging module described in this embodiment should not be regarded as a limitation on the specific structure of the present invention, and those skilled in the art can choose other types of speed sensors or ranging sensors as needed.

[0067] According to a preferred embodiment, the Hall speed sensor can be mounted on the vehicle wheels to measure the real-time speed of the electric vehicle. Further, the Hall speed sensor sends the collected speed information to a control module 4 (such as an STM32 microcontroller), which can generate modulation commands for driving the eddy current retarder 6 based on an internally preset program algorithm.

[0068] According to a preferred embodiment, an ultrasonic ranging module can be installed on the vehicle wheels to measure the real-time distance of the electric vehicle relative to a target obstacle within its direction of travel / range. Specifically, there can be one or more ultrasonic ranging modules, thus, multiple ultrasonic ranging modules can be arranged around the vehicle body at preset angles and / or distances. Specifically, the ultrasonic ranging module can include an ultrasonic transmitter, a receiver, and a control circuit. When the internal processor of the module receives a high level exceeding 10µs on the Trig, it cyclically sends eight 40kHz pulses to the transmitting circuit and detects whether there is an echo in the receiving circuit. Once an echo signal is detected, a high level is output on the Echo. The duration of the high level is the time it takes for the ultrasonic wave to travel from transmission to return, and the echo level output is proportional to the detection distance.

[0069] According to a preferred embodiment, the modulation command generated by the control module 4 based on the speed information obtained by the Hall speed sensor and the relative distance information obtained by the ultrasonic ranging module may include adjusting the pulse wave of the PWM output. This pulse wave is transmitted through the conversion module 5 (such as a voltage-to-current module) to input a suitable current into the eddy current retarder 6 to generate braking force, thereby realizing the functions of intelligent speed control and emergency braking. In particular, the microcontroller integrates a hardware PWM output unit. In the program, the PWM output of the microcontroller can be changed by simply writing data to the PWM-related registers and changing the duty cycle.

[0070] Optionally, considering the environmental changes during cycling and the practicality of the control equipment, the Hall speed sensor selected in this invention features high sensitivity to magnetic fields, high frequency response, and strong anti-electromagnetic interference capability. Furthermore, the ultrasonic ranging module exhibits stable performance, a small blind zone, and is unaffected by external light and electromagnetic fields, enabling it to output signals stably, thereby achieving accurate speed and distance measurement.

[0071] In particular, Figure 1 (a) shows a simplified structural diagram of the electromagnetic assisted braking device / system based on closed-loop control provided by the present invention. Figure 1 (b) shows a schematic diagram of the STM32 microcontroller. Figure 1 (c) shows a schematic diagram of the PCB board structure of the STM32 microcontroller.

[0072] In particular, since electric bicycles have low speeds and small size, this invention selects a rotary drum type eddy current retarder by comparing various auxiliary braking methods. It is small in size, easy to assemble, and suitable for low-speed applications.

[0073] According to a preferred embodiment, see Figure 4-6 The eddy current retarder 6 may include an outer nut 61, a first inner nut 62, a fixed bracket 63, a stator 64, a second inner nut 65, and a rotating drum 66. Specifically, the rotating drum 66 is located on the side of the electric bicycle without a drum brake and is coaxially distributed with the wheel 67. The rotating drum 66 is fixed to the outside of the wheel 67 by the second inner nut 65 (such as an Allen screw) to ensure synchronous rotation between them. The stator 64 is placed coaxially with the rotating drum 66. In particular, there is a uniform air gap between the inner surface of the rotating drum 66 and the stator 64 to prevent mutual friction. The stator 64 is fixed to the outermost bracket housing (such as the fixed bracket 63) by the first inner nut 62 (such as an Allen screw) and the outer nut 61, and does not rotate with the wheel 67. The outermost bracket housing is connected to the bracket on the same side of the electric bicycle by nuts, and the entire device is fixed to the wheel axle with nuts.

[0074] According to a preferred embodiment, in terms of material selection for the rotating drum 66, pure iron is chosen as its main material due to its high magnetic permeability and low remanence. Furthermore, to enhance the heat dissipation performance of the eddy current retarder 6, heat dissipation blades can be cast onto the outer surface of the rotating drum 66. Specifically, the heat dissipation blades include, but are not limited to, ribs, fins, etc. Further, a plurality (e.g., an even number) of iron cores made of high magnetic permeability material are fitted onto the stator 64. Specifically, the high magnetic permeability material can be selected from one or a combination of iron-silicon-aluminum alloys, iron-aluminum alloys, and nickel-based alloys. Preferably, these high magnetic permeability cores are circumferentially distributed and mounted on a high-strength mounting frame housing with substantially uniform gaps. Excitation coils are fitted onto the iron cores, together forming magnetic poles.

[0075] Specifically, the working principle of the eddy current retarder 6 is as follows: During vehicle operation, the Hall effect speed sensor measures the real-time speed of the vehicle and transmits the signal to the control module 4 (such as an STM32 microcontroller). The control module 4 adjusts the pulse wave output by the PWM, and then the voltage-to-current conversion module 5 inputs a suitable current to the eddy current retarder to generate braking force. Further, when the eddy current retarder 6 is working, the current passes through the excitation coil of the stator 64 to generate an alternating magnetic field. The rotor (drum 66) rotates in the alternating magnetic field, cutting the magnetic field lines and generating a reverse force. Because the stator 64 is fixed, and the rotor (drum 66) is connected to the drive shaft, the rotor (drum 66) rotates with the drive shaft. Thus, the stator 64 applies an electromagnetic force to the rotor (drum 66) that opposes its rotation, thereby generating a braking torque and achieving the purpose of decelerating the vehicle.

[0076] It is understood that the specific structure and working principle of eddy current retarders are relatively mature, so this invention will not elaborate on them further. Furthermore, the rotary drum-type eddy current retarder described in this embodiment should not be considered a limitation on the specific structure of this invention; those skilled in the art can choose other types of eddy current retarders 6 as needed.

[0077] According to a preferred embodiment, Figure 2 The diagram illustrates the hardware working principle of the electromagnetic assisted braking system provided by this invention. Specifically, during the operation of the electric bicycle, the drive wheel rotates, and the Hall effect speed measuring device and the ultrasonic ranging module acquire the speed and relative distance information of the electric bicycle, respectively. Further, in response to the acquired speed and relative distance information, the embedded control center generates a modulation signal for controlling the eddy current retarder based on the speed and distance requirements. This modulation signal is converted into a current signal by a voltage-to-current transmitter and input to the eddy current retarder. The eddy current retarder receives this modulation current, causing the excitation coil of the stator 64 in the eddy current retarder to generate an alternating magnetic field. The rotating drum 66 rotates in the alternating magnetic field, cutting the magnetic field lines and generating a reverse force. This reverse force serves as the braking torque to reduce the speed of the drive wheel.

[0078] Based on the above-described electromagnetic assisted braking system with closed-loop control, the present invention also provides a control method for the electromagnetic assisted braking system with closed-loop control, which may include the following steps:

[0079] The detection module acquires the speed and / or relative distance information of electric vehicles in real time.

[0080] The control module 4 generates modulation commands for driving the eddy current retarder 6 based on speed information and / or relative distance information.

[0081] The eddy current retarder 6 generates a modulating force in response to the modulation command of the control module to control the speed and / or relative distance of the vehicle.

[0082] According to a preferred embodiment, the control module 4 may generate modulation commands for driving the eddy current retarder 6 based on speed information and / or relative distance information, including:

[0083] When the electric vehicle's speed exceeds a first speed threshold, a corresponding modulation current is input to the eddy current retarder 6 based on the difference between the speed and the first speed threshold to generate an adjustable modulation force.

[0084] According to a preferred embodiment, the control module 4, based on speed information and / or relative distance information, generates modulation commands for driving the eddy current retarder 6, further including:

[0085] The relative distance to the electric vehicle is obtained when the electric vehicle's speed is between a first speed threshold and a second speed threshold.

[0086] When the relative distance between the electric vehicles is less than or equal to the first distance threshold, a corresponding modulation current is input to the eddy current retarder 6 based on the difference between the driving speed and the second speed threshold to generate an adjustable modulation force.

[0087] Furthermore, the control module 4, based on speed information and / or relative distance information, generates modulation commands for driving the eddy current retarder 6, which also includes:

[0088] When the electric vehicle's speed is less than the second speed threshold, the relative distance to the electric vehicle is obtained.

[0089] When the relative distance between the electric vehicles is less than or equal to the second distance threshold, a corresponding modulation current is input to the eddy current retarder 6 based on the difference between the driving speed and the second speed threshold to generate an adjustable modulation force.

[0090] According to a preferred embodiment, based on the "Electric Bicycle Safety Technical Specifications" and the "Road Traffic Safety Law," the first speed threshold in this invention can be 25 km / h. The second speed threshold can be 15 km / h. Further, the first distance threshold can be 2.5 m. The second distance threshold can be 2 m. It should be understood that, in other cases, the speed thresholds and distance thresholds listed in this invention as adjustment of vehicle speed and braking force can be selectively adjusted as needed.

[0091] According to a preferred embodiment, scenarios involving speed control or deceleration during electric vehicle operation typically include two situations: speeding and the presence of obstacles ahead. Specifically, during electric vehicle operation, if there are no obstacles ahead but the drive wheel speed exceeds 25 km / h (i.e., speeding), the Hall effect speed sensor generates a pulse signal of the corresponding frequency and transmits the processed signal to the embedded control center. The microcontroller adjusts the PWM output pulse wave by changing the duty cycle. After processing by the voltage-to-current converter (which converts the PWM pulse into a corresponding current), the output current increases. Then, the eddy current retarder rotates the drum to generate braking torque, thereby reducing the drive wheel speed. During deceleration, the Hall effect speed sensor can still generate corresponding pulse signals, thus changing the PWM output pulse wave, leading to a change in the output current. This, in turn, changes the magnitude of the braking force generated by the induced magnetic field, reducing the angular velocity of the drive wheel. This process repeats until the drive wheel speed is less than 25 km / h, meeting the expected value, at which point the microcontroller stops outputting the PWM signal (the speed modulation process achieves the expected angular velocity).

[0092] On the other hand, when an obstacle appears in front of the electric vehicle while it is in motion, and the speed of the drive wheels is between 15km / h and 25km / h, the ultrasonic ranging module sends eight 40kHz pulses to the transmitting circuit in a loop and detects whether there is an echo in the receiving circuit. At this time, the echo signal is detected, the ranging is realized, and the signal is transmitted to the central core of the embedded system. The microcontroller changes the duty cycle to adjust the pulse wave output by the PWM. After being processed by the voltage-to-current transmitter, the output current is increased. Then, the eddy current retarder makes the drum rotate to generate braking torque, thereby reducing the speed of the drive wheels and completing emergency braking.

[0093] In particular, Figure 3 A detailed flowchart of a control method for an electromagnetic assisted braking system provided by the present invention is shown. See also... Figure 3 The electromagnetic auxiliary braking system control method provided by this invention specifically includes: when the electric bicycle is in normal operation, a Hall sensor detects the speed in real time and continuously transmits signals to the embedded control center. According to GB17761-2018 "Safety Technical Specifications for Electric Bicycles," the maximum speed of an electric bicycle should not exceed 25 km / h. When the speed of the electric bicycle approaches or exceeds 25 km / h, an eddy current retarder actively reduces the speed to control the speed at or below the specified speed of 25 km / h.

[0094] On the other hand, according to the Road Traffic Safety Law, the safe speed for electric bicycles traveling in non-motorized vehicle lanes should be 15 km / h. Therefore, when the speed of an electric bicycle is between 15 km / h and 25 km / h, the ultrasonic ranging module starts working, detecting the distance to obstacles in front of the vehicle in real time and transmitting the data back to the embedded control center. Specifically, when the distance between the front of the bicycle and the target obstacle is less than or equal to the first safe distance (e.g., 2.5m), the voltage-to-current transmitter adjusts the eddy current retarder to actively reduce speed and maintain a safe distance. Furthermore, when the speed of the electric bicycle is less than 15 km / h and the distance between the front of the bicycle and the target obstacle is less than or equal to the second safe distance (e.g., 2m), or when an emergency braking situation arises during riding, the eddy current retarder quickly works to reduce the speed, keeping the vehicle speed at or below 15 km / h before the rider can react. Afterward, the braking continues to assist in active speed reduction.

[0095] According to a preferred embodiment, when identifying obstacles, the identified obstacles are divided into static obstacles and dynamic obstacles based on the road conditions under which the electric vehicle travels. Dynamic obstacles are typically non-motorized vehicles traveling in the same direction. When following another vehicle, a safe distance of at least 2 meters must be maintained to prevent rear-end collisions.

[0096] Specifically, when the vehicle speed is between 15 km / h and 25 km / h, the data fed back by the ultrasonic ranging module will serve as the primary criterion. This ultrasonic ranging module detects the distance to obstacles in front of the vehicle in real time and transmits the data back to the embedded control center. When the transmitted distance is less than the safe distance, it indicates that there is an obstacle ahead, or that a safe following distance has not been maintained. At this time, the system outputs information, and the voltage-to-current transmitter adjusts the eddy current retarder to actively reduce the speed and maintain a safe distance. If the data transmitted by the ranging sensor is still less than the safe distance after reducing the vehicle speed, it indicates that there is a static obstacle ahead of the electric vehicle's path. The retarder will maintain operation to assist in reducing the vehicle speed to below 5 km / h and then stop working.

[0097] According to a preferred embodiment, Figure 7 The specific process of simulating and verifying the electromagnetic assisted braking system control method provided by this invention using a mathematical model is illustrated. Specifically, this invention uses the Simulink / MATLAB environment to simulate and verify the established mathematical model, introducing multiple influencing factors and utilizing error analysis to test the system's functionality and stability.

[0098] Specifically, such as Figure 7As shown, the electric bicycle is put into operation, and an initial instantaneous angular velocity value is assigned to the Hall sensor. The Hall sensor converts this initial instantaneous angular velocity value into an input signal and transmits it to the microcontroller. The microcontroller processes the input signal sent by the Hall sensor into a modulotable eddy current retarder input current I through a voltage-to-current converter. The eddy current retarder receives this input current I and generates a magnetic field B. The conductors in the eddy current retarder move relative to the magnetic field, thereby generating a braking torque T that reduces the vehicle speed. Further, under the action of the braking torque T, the vehicle speed decreases, and the current instantaneous angular velocity of the vehicle is acquired. It is then determined whether the vehicle speed corresponding to this instantaneous angular velocity exceeds the expected speed. If the vehicle speed is greater than the expected speed, the instantaneous angular velocity is transmitted to the Hall sensor and the microcontroller to execute the next round of braking and judgment process; conversely, if the vehicle speed is less than the expected speed, the braking target is met, and the entire vehicle deceleration process ends. In this simulation verification process, an initial value of instantaneous angular velocity is first assigned. Based on this initial value, a braking torque to reduce the vehicle speed is generated. The instantaneous angular velocity of the vehicle is continuously updated through cyclic braking until the vehicle speed reaches the expected speed, thereby completing the closed-loop control of the vehicle speed.

[0099] Specifically, after the Hall sensor receives the current wheel speed ω0 in a unit period t0, the microcontroller outputs a current I = αω0. The specific value of α can be determined by a custom program within the microcontroller. Furthermore, the magnetic flux density B obtained through the output current I, based on the fundamental principle of an electrically excited radial electromagnetic damper, generates a braking force (damping force) on the conductor, thereby achieving deceleration.

[0100] According to the torque expression in the calculation method of braking torque for rotary eddy current retarder:

[0101]

[0102] And the expressions for the magnetic flux density B and the microcontroller output current I:

[0103]

[0104] The relationship between the final angular velocity and the initial angular velocity can be obtained, until the ω value is input into the microcontroller. n The expected value has been met.

[0105] In particular, the auxiliary braking system provided by this invention offers a significant improvement in braking distance compared to no system. A more significant improvement lies in the fact that the device, through real-time speed control, ensures that the driver's speed remains within a safe range during operation, significantly reducing damage from collisions. Simultaneously, the device considers the human body's perception of speed fluctuations during this process. The maximum acceleration value perceived by the human body during this process is a = 2.088 m / s², which is within the maximum acceptable speed fluctuation range for the human body. This ensures that emergency obstacle avoidance during this phase of driving will not cause discomfort to the human body. Therefore, this device has a significantly effective role in emergency obstacle avoidance and the protection of the driver.

[0106] Preferably, when performing relative distance information determination, this solution can have multiple determination directions. In a preferred embodiment, at least there are relative distances within the same lane and relative distances between the vehicle and other vehicles. The relative distance within the same lane refers to the detected distance between the target object or obstacle (usually the vehicle in front) and the vehicle when they are in the same lane. The relative distance between other vehicles refers to the distance between the target object or obstacle (usually the vehicle diagonally ahead) and the vehicle when they are not in the same lane.

[0107] According to a preferred embodiment, if the relative distance to the vehicle in the current lane is not measured or its value is "infinite," the system further detects whether a detection value exists for the relative distance to the outer lane. If it exists, the system further determines whether the relative distance to the outer lane is less than the distance warning detection value and whether the current vehicle speed is less than the speed warning detection value. If the distance is less than and the speed is greater than the corresponding warning detection value, the system controls the decelerator to apply brakes and control the speed below the speed warning detection value. On the other hand, if one or both of the following conditions are met: the relative distance to the outer lane is greater than the distance warning detection value or the current vehicle speed is less than the speed warning detection value, then no subsequent actions are performed. In particular, the aforementioned distance warning detection value and speed warning detection value can be manually set. Specifically, when setting the speed warning detection value, the maximum acceleration value perceived by the human body, 2.088 m / s², can be used as a reference. 2 The calculation is performed so that, when the vehicle is at its maximum speed limit (e.g., the aforementioned mandatory 25 km / h), the acceleration is no greater than 2.088 m / s² when decelerating to the speed warning detection value. 2 .

[0108] Preferably, the vehicle has a collision measurement area based on its collision calculation matrix. The collision calculation matrix refers to model data formed by measuring, pre-setting, or estimating the vehicle's external dimensions; the model can characterize the vehicle's external features. The collision measurement area is the region requiring collision measurement, calculated based on the collision calculation matrix. For example, when the vehicle is traveling straight, the collision measurement area is a straight-moving region defined forward from the boundary of the collision calculation matrix.

[0109] Specifically, this solution finds that outside the main vehicle driving area, i.e., the aforementioned collision measurement area, although vehicles in these areas may not temporarily affect the normal driving of this vehicle, there is a possibility that a vehicle outside the area may suddenly change lanes, causing other vehicles to suddenly appear in the collision measurement area, forcing this vehicle to decelerate suddenly, resulting in a deceleration value greater than the aforementioned 2.088 m / s². 2 This can cause discomfort to people and, in severe cases, cause the vehicle to tilt forward due to inertia, resulting in injuries. Therefore, preferably, the area "outside the collision measurement area" is referred to as the extra-domain area.

[0110] Preferably, when the vehicle is in motion and at least one other vehicle is detected in an area outside the detection zone, the distance between the vehicle and that other vehicle in the outside detection zone is obtained, as well as the angle between the vehicle and that other vehicle in the outside detection zone. The braking force (or modulated current) of the vehicle is adjusted based on the correlation between the distance and the angle. Furthermore, the angle reflects the desire of other vehicles to change lanes; the smaller the angle, the more likely the vehicle in the outside detection zone intends to change lanes. Distance reflects the time required for a lane change and the reaction time; the closer the distance, the shorter the reaction time once a lane change occurs.

[0111] Specifically, when multiple vehicles or one other vehicle exist in the area outside the designated area, the system selects the highest priority braking current scheme from all available braking current schemes based on the classification range of the vehicle's outside measurement angle and distance compared to other vehicles, and controls the aforementioned eddy current retarder to perform braking based on this braking current. Further, the outside measurement angle and outside measurement distance can be divided into at least two categories based on preset judgment values, referred to as the first category and the second category. The first category for outside measurement angles is the category with smaller angles, and the second category is the category with larger angles. Similarly, the first category for outside measurement distances is the category with smaller distances, and the second category is the category with larger distances. Based on these two parameter classifications, the actual situation of a vehicle falls within at least one case matrix consisting of pairwise combinations of these two parameters.

[0112] In the above priority scheme, this scheme sets the highest priority (first priority) for both the external measurement angle and the external measurement distance being in the first category. The next highest priority is the external measurement angle in the first category and the external measurement distance in the second category. The next highest priority is the external measurement angle in the second category and the external measurement distance in the first category. The lowest priority is the external measurement angle in the second category and the external measurement distance in the second category. Specifically, corresponding to the above four priority scenarios, there are four different braking currents, arranged in the order of braking current magnitude: first priority > second priority > third priority > fourth priority.

[0113] In other words, in this invention, the processor (microcontroller) can generate a modulation command (i.e., a modulation current) that varies in relation to the external measurement angle and / or external measurement distance of target obstacles in the external region related to the collision measurement area of ​​the electric bicycle. Specifically, the relationship between the braking current and the distance and angle can be calculated from a predetermined functional relationship, or the relationship between speed, angle, and distance can be determined using a preset table. For example, a suitable automatic current magnitude can be obtained by looking up a table. Furthermore, if there are multiple target obstacles in the external region, a braking scheme that includes at least the corresponding pre-modulated current is determined based on the classification range of the external measurement angle and / or external measurement distance between the electric bicycle and the multiple target obstacles, ordered by priority.

[0114] The above solution addresses the lane-changing intentions of vehicles outside the designated area. Although these vehicles are not the primary focus, their sudden lane changes can still cause the vehicle to brake too late or accelerate excessively, leading to a rollover. Unlike four-wheeled vehicles, two-wheeled vehicles are at a disadvantage in deceleration, making them more prone to injury. Therefore, this solution addresses this by designing a more flexible pre-deceleration mechanism. It outputs a pre-modulated current based on the vehicle's relative distance and the outside-area measurement angles of other vehicles. This pre-modulated current is adjusted in relation to these measurements, allowing for intelligent pre-deceleration control based on various scenarios (multiple surrounding vehicles, a single vehicle in different positions). This ensures that even if surrounding vehicles suddenly change lanes, the vehicle can decelerate with lower acceleration, significantly improving the safety of the driver and passengers.

[0115] Preferably, this solution takes into account that, unlike four-wheeled vehicles, electric bicycles, being two-wheeled vehicles, typically have riders whose body outlines are not included in the vehicle's field of vision. This means that in the event of a collision or scrape, injury often occurs to the rider rather than the vehicle itself. Existing technologies, when determining whether a vehicle has collided with another object, use a pre-defined, fixed reference outline of the vehicle's volume or outline, using this original reference outline as a benchmark for collision determination. However, this solution considers this approach to need improvement for the aforementioned reasons. Therefore, preferably, the original reference outline has multiple levels, each level differing at least in area, and preferably, the area gradually increases with each level. Preferably, when determining whether a collision has occurred, different reference outline levels are selected according to the aforementioned different priorities. Specifically, in the first priority case, the original reference outline with the largest area is preferably selected; in the second priority case, the original reference outline with the next largest area is preferably selected, and so on for the third and fourth priorities. The above solution can intelligently determine the original reference contour size based on the priority of judgment, so as to leave enough judgment redundancy in more dangerous situations. In cases where the driver's contour of an electric bicycle is likely to exceed the vehicle contour and may be equipped with large items, it can better slow down in advance to avoid collisions that could cause personal injury or death.

[0116] Those skilled in the art will understand that, as long as the objectives of the present invention can be achieved, other steps or operations may be included before, after, or between steps a, b, and / or S1-S3, for example, to further optimize and / or improve the method described in the present invention. Furthermore, although the method described in the present invention is shown and described as a series of actions performed sequentially, it should be understood that the method is not limited by the order of these actions. For example, some actions may occur in a different order than that described herein. Alternatively, one action may occur simultaneously with another action.

[0117] It should be noted that the specific embodiments described above are exemplary. Those skilled in the art can devise various solutions inspired by the disclosure of this invention, and these solutions all fall within the scope of this invention and its protection. Those skilled in the art should understand that this specification and its accompanying drawings are illustrative and not intended to limit the scope of the claims. The scope of protection of this invention is defined by the claims and their equivalents. This specification contains multiple inventive concepts; terms such as "preferredly," "according to a preferred embodiment," or "optionally" indicate that the corresponding paragraph discloses an independent concept. The applicant reserves the right to file divisional applications based on each inventive concept.

Claims

1. An electromagnetic assisted braking system based on closed-loop control, characterized in that, include: A detection module is used to acquire vehicle speed information and / or relative distance information. The detection module includes a speed sensor (1) and a ranging module (3). The ranging module (3) performs ranging operations in association with the speed information acquired by the speed sensor (1). The control module (4) is capable of generating modulation commands for driving the eddy current retarder (6) based on the speed information and / or relative distance information. An eddy current retarder (6) is operatively coupled to the vehicle and is capable of generating a modulating force for controlling the speed and / or relative distance of the vehicle in response to a modulation command from the control module (4). The generation of modulation commands for driving the eddy current retarder (6) based on the speed information and / or relative distance information includes: When the vehicle's speed is greater than a first speed threshold, a corresponding modulation current is input to the eddy current retarder (6) based on the difference between the speed and the first speed threshold to generate an adjustable modulation force. When the vehicle's speed is between a first speed threshold and a second speed threshold, the relative distance to the vehicle is obtained; When the relative distance is less than or equal to the first distance threshold, a corresponding modulation current is input to the eddy current retarder (6) based on the difference between the driving speed and the second speed threshold to generate an adjustable modulation force; When the vehicle's speed is less than the second speed threshold, obtain the relative distance between the vehicles; When the relative distance is less than or equal to the second distance threshold, a corresponding modulation current is input to the eddy current retarder (6) based on the difference between the driving speed and the second speed threshold to generate an adjustable modulation force; The control module (4) generates modulation commands that vary in relation to the outside measurement angle and / or outside measurement distance of the target obstacle in the outside region related to the collision measurement area of ​​the electric bicycle.

2. The electromagnetic assisted braking system based on closed-loop control according to claim 1, characterized in that, It also includes a conversion module (5), which is capable of converting the modulation command generated by the control module (4) related to the speed information and / or relative distance information into a modulation current and providing it to the eddy current retarder (6).

3. The electromagnetic assisted braking system based on closed-loop control according to claim 1, characterized in that, It also includes a power supply module (2) for supplying electrical energy to the detection module and / or control module (4).

4. The electromagnetic assisted braking system based on closed-loop control according to claim 1, characterized in that, The detection module includes: Speed ​​sensor (1) is used to acquire vehicle speed information; The distance measuring module (3) is used to obtain the relative distance information of the vehicles.

5. A control method for an electromagnetic assisted braking system based on closed-loop control as described in any one of claims 1 to 4, characterized in that, include: Acquire vehicle speed information and / or relative distance information; Based on the speed information and / or relative distance information, a modulation command is generated for driving the eddy current retarder (6); The eddy current retarder (6) generates a modulation force in response to the modulation command for controlling the speed and / or relative distance of the vehicle.

6. The control method according to claim 5, characterized in that, The modulation command for driving the eddy current retarder (6) is generated based on the speed information and / or relative distance information and is executed by a preset program command based on the correlation between the speed information and / or relative distance information and the change of a set threshold over time.

7. An electric vehicle, characterized in that, Including the electromagnetic assisted braking system based on closed-loop control as described in any one of claims 1 to 4.

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