An electro-mechanical braking system and control method

Abstract

The present invention discloses an electro-mechanical braking system and a control method. Among them, the motor housing is provided with a hollow cylindrical inner cavity, and the right end is connected with a caliper body. The inner cavity of the caliper body is communicated with the motor housing. A caliper is provided at the right end of the caliper body. Stator windings are distributed around in the inner cavity of the motor housing. The motor rotor is rotatably arranged at the center of the inner cavity of the motor housing corresponding to the stator windings. A cylindrical mounting groove is formed at the right end of the motor rotor. A planetary reduction mechanism is installed in the mounting groove. The input end of the planetary reduction mechanism is connected to the motor rotor, and the output end of the planetary reduction mechanism is connected to one end of a central lead screw. The other end of the central lead screw extends into the inner cavity of the caliper body, and a plurality of planetary rollers are wound around and threadedly driven on the outside. A lead screw nut is commonly threadedly sleeved on the outside of the plurality of planetary rollers. The lead screw nut is slidably arranged in the inner cavity of the caliper body. A piston end cover is installed at the right end of the lead screw nut. The system of the present invention improves the integration degree and braking efficiency, and the method enhances the response performance and braking smoothness.

Description

Technical Field

[0001] The present invention relates to the technical field of automotive electro-mechanical braking, and particularly relates to an electro-mechanical braking system and a control method. Background Art

[0002] As an important development of modern braking systems, Brake-by-Wire technology is gradually showing a trend to replace traditional mechanical and hydraulic braking systems. In traditional braking systems, the movement of the brake pedal is transmitted to the brake through mechanical transmission or hydraulic pipelines, which have problems such as long response time, complex system, large weight, and high maintenance difficulty. With the progress of electronic control technology, the Brake-by-Wire mechanism processes signals from the brake pedal through an electronic control unit (ECU) and converts the electrical signals into actual braking force through the mechanism, achieving higher control accuracy and response speed. This technology not only simplifies the system structure, reduces the vehicle weight, but also improves the overall system integration and reliability.

[0003] However, the existing Brake-by-Wire mechanisms have low integration, and still have deficiencies in response speed, redundant design, and cost control, which limit their application in a wider range of fields. Therefore, aiming at the deficiencies of the existing technology, there is an urgent need to provide an electro-mechanical braking system and a control method to solve the problem of low integration of the existing Brake-by-Wire mechanisms. Summary of the Invention

[0004] In view of the deficiencies in the prior art, the present invention provides an electro-mechanical braking system and a control method to solve the problem of low integration of the existing Brake-by-Wire mechanisms.

[0005] To achieve the above object, the present invention adopts the following technical solutions:

[0006] An electro-mechanical braking system includes a motor mechanism, a planetary reduction mechanism, a braking mechanism, a piston end cover, and a caliper body. The motor mechanism includes a motor housing, a stator winding, and a motor rotor. The braking mechanism includes a central lead screw, planetary rollers, and a lead screw nut. The motor housing has a hollow inner cavity and is connected to the caliper body at its right end. The inner cavity of the caliper body communicates with the motor housing. A caliper is provided at the right end of the caliper body. A ring of stator windings is distributed around the inner cavity of the motor housing. The motor rotor is rotatably arranged at the center of the inner cavity of the motor housing corresponding to the stator winding. An installation groove is formed at the right end of the motor rotor. The planetary reduction mechanism is installed in the installation groove. The input end of the planetary reduction mechanism is connected to the motor rotor, and the output end of the planetary reduction mechanism is connected to one end of the central lead screw. The other end of the central lead screw extends into the inner cavity of the caliper body, and several planetary rollers are wound around and threadedly driven on the outside. A lead screw nut is commonly threadedly sleeved on the outside of the several planetary rollers. The lead screw nut is slidably arranged in the inner cavity of the caliper body, and a piston end cover is installed at the right end of the lead screw nut. The lead screw nut is used to drive the piston end cover to move closer to or away from the caliper along the inner cavity of the caliper body.

[0007] To optimize the above technical solution, the specific measures taken also include:

[0008] Further, a left end cover is connected to the left end of the motor housing. An angular contact ball bearing A is connected to the inner side of the left end cover in a ring, and the motor rotor is rotatably connected through the angular contact ball bearing A.

[0009] Further, a through hole is formed at the center of the left end cover. The input end of the planetary reduction mechanism passes through the motor rotor and extends leftward from the through hole of the left end cover. An encoder end cover is installed on the left side of the through hole of the left end cover. The space between the encoder end cover and the input end of the planetary reduction mechanism is the encoder installation space.

[0010] Further, the planetary reduction mechanism includes a sun gear as the input end, planetary gears, an internal gear ring, and a planetary carrier. The center of the left end face in the installation groove of the motor rotor is fixedly connected with a sun gear coaxially with it. The end of the sun gear located in the installation groove meshes with several equally spaced planetary gears. The internal gear ring is in a cylindrical shape and is arranged in the installation groove. A ring of teeth for meshing with the planetary gears is provided on the inner side of the left end. The right end is fixedly connected to the right end of the motor housing. A planetary carrier coaxial with the sun gear is rotatably arranged inside the internal gear ring. An output through hole for fixedly connecting with the central lead screw is provided at the center of the planetary carrier. Several coaxial sub-through holes corresponding to the planetary gears are provided around the output through hole on the planetary carrier. The planetary gear shafts on the planetary gears are respectively rotatably arranged in the corresponding sub-through holes.

[0011] Further, the inner side of the internal gear ring is rotationally connected to the planet carrier through an angular contact ball bearing C, and the planet gear shaft is rotationally connected to the sub-through hole of the planet carrier through an angular contact ball bearing B.

[0012] Further, the right end of the motor housing is connected to the pliers body through a circumferential flanging disc. The flanging disc extends inward into the installation groove of the motor rotor, and a circumferential thrust bearing is provided on the inner wall located in the installation groove, and a circumferential retaining disc is rotationally connected through the thrust bearing. The central lead screw has a stepped shaft configuration, and the right end of the retaining disc abuts against a shoulder of a section of the central lead screw.

[0013] Further, a slideway is axially provided in the inner cavity of the pliers body, and the lead screw nut is limited and slidably connected to the inner cavity of the pliers body through a guide flat key.

[0014] Further, a control method, characterized in that it includes the following steps:

[0015] Collect the braking pedal depth d and the stepping speed w, and input them into a preset fuzzy control system. The fuzzy control system outputs the desired braking intensity z;

[0016] According to the desired braking intensity z and vehicle parameters, use the formula to calculate the desired braking torque :

[0017] ;

[0018] In the formula, m is the vehicle mass, g is the acceleration due to gravity, is the rolling radius of the vehicle wheel;

[0019] After obtaining the desired braking torque According to the parameters of the planetary reduction mechanism and the planetary rollers, derive the relationship between the target current required for the motor mechanism to output and the required desired braking torque :

[0020] ;

[0021] ;

[0022] ;

[0023] ;

[0024] Then:

[0025] ;

[0026] ;

[0027] In the formula: is the electromagnetic torque, is the number of pole pairs of the motor, is the permanent magnet flux linkage, and are the components of the current in the stator winding on the d-axis and q-axis respectively, and are the inductances of the d-axis and q-axis respectively, n is the transmission ratio of the planetary reduction mechanism, is the efficiency of the planetary roller transmission pair, is the output torque of the planetary reduction mechanism, is the clamping force of the braking mechanism, is the lead of the central lead screw, is the effective radius of the brake disc, is the friction coefficient between the friction plate and the brake disc;

[0028] According to the calculation, is obtained as the target current, and according to the obtained target current, the control signal of the motor mechanism is output.

[0029] Furthermore, it also includes the following steps:

[0030] Introduce a smoothing coefficient s and establish the following relationship:

[0031] ;

[0032] ;

[0033] ;

[0034] Then:

[0035] ;

[0036] ;

[0037] According to the calculation, is obtained as the improved target current, and according to the improved target current, the control signal of the motor mechanism is output.

[0038] Furthermore, the processing of the fuzzy control system includes the following steps:

[0039] Divide the input variables into 4 fuzzy sets and the output variables into 5 fuzzy sets;

[0040] Formulate the fuzzy set of the input variable 1, the depth d of the brake pedal ∈ [0, 100]%: {very shallow (VSd), shallow (Sd), medium deep (Md), deep (Ld)}, divide it into four equal parts according to every 25%, and determine the membership function as:

[0041] ;

[0042] ;

[0043] ;

[0044] ;

[0045] Formulate the fuzzy set of the input variable 2 pedal speed w ∈ [0, 10] cm / s: {Very Slow (VSw), Slow (Sw), Medium Speed (Mw), Fast (Lw)}, divide it into four equal parts at every 2.5 cm / s, and determine the membership function as:

[0046] ;

[0047] ;

[0048] ;

[0049] ;

[0050] Formulate the fuzzy set of the output variable braking intensity Z ∈ [0, 100]%: {Very Small (VSZ), Small (SZ), Medium (MZ), Large (LZ), Very Large (VLZ)}, divide it into five equal parts at every 20%, and determine the membership function as:

[0051] ;

[0052] ;

[0053] ;

[0054] ;

[0055] ;

[0056] According to driving experience and vehicle performance, formulate i fuzzy rules Ri. The principle of the fuzzy rule Ri is to obtain the corresponding elements in the fuzzy set of the braking intensity Z based on different elements in the fuzzy set of the pedal depth d and different elements in the fuzzy set of the pedal speed w;

[0057] Use the fuzzy inference mechanism to perform inference based on the fuzzified input and fuzzy rules, and for each fuzzy rule Ri, calculate the corresponding activation intensity :

[0058] ;

[0059] Wherein, is the output of the membership function corresponding to the braking pedal depth d in the i-th fuzzy rule, is the output of the membership function corresponding to the stepping speed w in the i-th fuzzy rule. The value range of Ai is VSd, Sd, Md, and Ld, and the value range of Bi is VSw, Sw, Mw, and Lw;

[0060] The output fuzzy set of each fuzzy rule is trimmed by the activation intensity, that is:

[0061] ;

[0062] is the output of the membership function of the braking intensity Z in the i-th fuzzy rule determined by the braking pedal depth d and the stepping speed w. The value range of Ci is VSZ, SZ, MZ, LZ, and VLZ, is the rule output of the i-th fuzzy rule;

[0063] If i ranges from 1 to H, then the outputs of all rules are superimposed:

[0064] ;

[0065] Convert the fuzzy representation of the braking intensity Z obtained by fuzzy inference into a specific numerical value. The discrete centroid method is used for defuzzification. The braking intensity Z is divided into h points, and the weighted sum is calculated:

[0066] ;

[0067] is the percentage of the braking intensity. Define the influence range of the road condition as [0 - a], where a is the road condition coefficient and 0 < a ≤ 1; then, the final expected braking intensity z is z = a.

[0068] The beneficial effects of the present invention are:

[0069] The system of the present invention designs the motor mechanism as a hollow structure, and at the same time designs the motor rotor as a hollow structure, so as to facilitate the installation of the planetary reduction mechanism, reduce the space occupied by the entire structure, improve the integration of the electro-mechanical braking system. Further, the planetary reduction mechanism can be used to amplify the output torque of the motor mechanism, improve the output effect, enhance the braking efficiency, and solve the problem of low integration of the existing wire-controlled braking mechanism; at the same time, the braking mechanism adopts a planetary roller drive structure. In this connection mode, when the lead screw nut is circumferentially fixed, the central lead screw rotates to drive several planetary rollers to perform planetary motion, and the planetary rollers drive the lead screw nut to move axially. During the process, there is no relative movement between the planetary rollers and the nut axially, ensuring precise control and response speed, and significantly improving the reliability and safety of the braking performance.

[0070] The system of the present invention can not only respond to the braking demands of the driver, but also achieve more delicate braking adjustment through electronic control strategies, thereby enhancing the overall driving safety. In addition, this design has good compactness and reliability in structure, wide adaptability, and can meet the requirements of different vehicle models. The electro-mechanical braking system improves the braking response speed of the vehicle while effectively enhancing the driving comfort and safety, demonstrating good engineering application value and broad market prospects.

[0071] The control method of the present invention first significantly improves the torque and winding current of the motor mechanism during the stage of overcoming the braking clearance, reduces the gap between the actual output torque of the motor mechanism and the locked-rotor torque, and can also shorten the time required to overcome the braking clearance without changing the structure of the control strategy, thereby enhancing the response performance of the brake and the smoothness of braking, and reducing the variable load received by the braking mechanism. The desired braking torque is determined by the depth of the brake pedal. Therefore, after establishing the functional relationship between the smoothness coefficient and the pedal depth, the size of the smoothness coefficient can be dynamically adjusted according to the depth of the driver stepping on the brake pedal.

[0072] The control method of the present invention realizes the decoupling between the brake pedal and the brake execution system, performs wire-controlled braking through electrical signals, improves the integration and modularization degree of the vehicle braking system, better responds to the trend of vehicle electrification, realizes the rapid response to the wheel braking process, reduces the impact of the sudden stator winding current on the motor, and enhances the smoothness of the braking process. Brief Description of the Drawings

[0073] Figure 1 It is a sectional view of the overall structure of an electro-mechanical braking system proposed by the present invention;

[0074] Figure 2 It is an exploded view of the overall structure of an electro-mechanical braking system proposed by the present invention;

[0075] Figure 3 It is a schematic structural diagram of the braking mechanism of an electro-mechanical braking system proposed by the present invention;

[0076] Figure 4 It is a schematic structural diagram of the planetary reduction mechanism of an electro-mechanical braking system proposed by the present invention;

[0077] Figure 5 It is a schematic structural diagram of the left end cover of an electro-mechanical braking system proposed by the present invention;

[0078] Figure 6 It is a schematic flow diagram of the control method of an electro-mechanical braking system proposed by the present invention.

[0079] Reference numerals: 1. motor mechanism, 1-1. motor housing, 1-2. stator winding, 1-3. motor rotor, 1-4. flash disk, 1-5. encoder end cover, 1-6. left end cover, 1-7. angular contact ball bearing A; 2. planetary reduction mechanism, 2-1. sun gear, 2-2. planetary gear, 2-3. planetary gear shaft, 2-4. internal gear ring, 2-5. planet carrier, 2-6. planet carrier retaining ring, 2-7. angular contact ball bearing B, 2-8. angular contact ball bearing C; 3. braking mechanism, 3-1. central lead screw, 3-2. planetary roller, 3-3. lead screw nut, 3-4. thrust bearing, 3-5. retaining disk; 4. right end cover; 5. piston end cover; 6. caliper body; 7. encoder installation space. Detailed implementation mode

[0080] The present invention will now be described in further detail with reference to the accompanying drawings.

[0081] As shown in the attached Figure 1 drawing, Figure 2 drawing Figure 3 and drawing

[0082] As shown in the drawings, an electromechanical braking system according to an embodiment of the present invention includes a motor mechanism 1, a planetary reduction mechanism 2, a braking mechanism 3, a piston end cover 5 and a caliper body 6. The motor mechanism 1 includes a motor housing 1-1, a stator winding 1-2 and a motor rotor 1-3. The braking mechanism 3 includes a central lead screw 3-1, a planetary roller 3-2 and a lead screw nut 3-3. The motor housing 1-1 is provided with a hollow cylindrical inner cavity, and the right end is connected to the caliper body 6 through a right end cover 4. The inner cavity of the caliper body 6 is communicated with the motor housing 1-1. A caliper is provided at the right end of the caliper body 6. A circle of stator windings 1-2 is distributed around the inner cavity of the motor housing 1-1. The motor rotor 1-3 is rotatably arranged at the center of the inner cavity of the motor housing 1-1 corresponding to the stator winding 1-2. A cylindrical installation groove is opened at the right end of the motor rotor 1-3. The planetary reduction mechanism 2 is installed in the installation groove. The input end of the planetary reduction mechanism 2 is connected to the motor rotor 1-3, and the output end of the planetary reduction mechanism 2 is connected to one end of the central lead screw 3-1. The other end of the central lead screw 3-1 extends into the inner cavity of the caliper body 6, and a plurality of planetary rollers 3-2 are wound around and threadedly driven on the outside. A lead screw nut 3-3 is commonly sleeved on the outside of the plurality of planetary rollers 3-2. The lead screw nut 3-3 is slidably arranged in the inner cavity of the caliper body 6 in the left-right direction, and a piston end cover 5 is installed at the right end of the lead screw nut 3-3. The lead screw nut 3-3 is used to drive the piston end cover 5 to move closer to or away from the caliper along the inner cavity of the caliper body 6.In the present invention, the motor mechanism 1 is designed as a hollow structure, and at the same time, the motor rotor 1-3 is designed as a hollow structure, so as to facilitate the installation of the planetary reduction mechanism 2, reduce the space occupied by the entire structure, and improve the integration of the electro-mechanical braking system. Further, the planetary reduction mechanism 2 can be used to amplify the output torque of the motor mechanism 1, improve the output effect, and solve the problem of low integration of the existing wire braking mechanism. At the same time, the braking mechanism 3 adopts a planetary roller 3-2 drive structure. In this connection mode, when the lead screw nut 3-3 is circumferentially fixed, the central lead screw 3-1 rotates to drive a plurality of planetary rollers 3-2 to perform planetary motion, and the planetary rollers 3-2 drive the lead screw nut 3-3 to move axially. During the process, there is no relative axial movement between the planetary rollers and the nut, ensuring the transmission effect and response speed.

[0083] As shown in the Figure 5 accompanying drawings. The left end of the motor housing 1-1 is connected to a left end cover 1-6. The inner side of the left end cover 1-6 is connected with a ring of angular contact ball bearings A1-7, and the motor rotor 1-3 is rotatably connected through the angular contact ball bearings A1-7.

[0084] A through hole is provided in the center of the left end cover 1-6. The input end of the planetary reduction mechanism 2 passes through the motor rotor 1-3 and extends leftward from the through hole of the left end cover 1-6. An encoder end cover 1-5 is installed on the left side of the through hole of the left end cover 1-6. The space between the encoder end cover 1-5 and the input end of the planetary reduction mechanism 2 is the encoder installation space 7. In this way, it is convenient to install and use the encoder for detecting the rotation angle of the motor rotor 1-3.

[0085] Specifically, the outer wall of the motor housing 1-1 can be rectangular for easy installation. Permanent magnets are evenly embedded around the motor rotor 1-3. After being energized, the magnetic field generated by the stator winding 1-2 and the magnetic field generated by the permanent magnets interact to drive the motor rotor 1-3 to perform a rotational motion, that is, the motion of the braking mechanism 3 can be controlled by controlling the on-off of the electromagnetic coil.

[0086] Specifically, the above planetary rollers 3-2 are evenly distributed around the central lead screw 3-1. The lead screw nut 3-3 is sleeved around the planetary rollers 3-2. Between the central lead screw 3-1 and the planetary rollers 3-2, and between the planetary rollers 3-2 and the lead screw nut 3-3, they are all connected by screw threads. Eleven planetary rollers 3-2 can be selected, and both ends are connected with fixing brackets. The end of the lead screw nut 3-3 is connected with a piston end cover 5 by screws. Among them, in a specific embodiment, the braking mechanism of the planetary rollers 3-2 uses a screw pair connection and converts rotational motion into linear motion. The thread profile angles of the central lead screw 3-1, the planetary rollers 3-2, and the lead screw nut 3-3 are 60°, the pitch is 0.5 mm, the lead is 2.5, and the number of thread starts is 5. Therefore, the actual lead is 0.5 mm. Under such parameters, when the lead screw nut 3-3 is circumferentially fixed, the eleven central lead screws 3-1 rotate to drive the eleven planetary rollers 3-2 to perform planetary motion, and the planetary rollers 3-2 drive the lead screw nut 3-3 to move axially. During the process, the planetary rollers 3-2 do not move axially.

[0087] Among them, on the opposite surfaces of the above piston end cover 5 and the caliper body 6 caliper, friction plates can be respectively arranged.

[0088] As shown in the Figure 4 accompanying figure, in another specific embodiment based on the above, the planetary reduction mechanism 2 includes a sun gear 2-1 as the input end, planetary gears 2-2, an internal gear ring 2-4, and a planet carrier 2-5. At the center of the left end face in the installation groove of the motor rotor 1-3, a sun gear 2-1 coaxial with it is fixedly connected. The end of the sun gear 2-1 located in the installation groove meshes with a number of equally spaced planetary gears 2-2. The internal gear ring 2-4 is cylindrical and arranged in the installation groove, and there is a ring of teeth for meshing with the planetary gears 2-2 on the inner side of the left end. The right end is fixedly connected to the right end of the motor housing 1-1. It is located between the motor housing 1-1 and the caliper body 6. Inside the internal gear ring 2-4, a planet carrier 2-5 coaxial with the sun gear 2-1 is rotatably arranged. At the center of the planet carrier 2-5, there is an output through hole for fixedly connecting with the central lead screw 3-1. Around the output through hole on the planet carrier 2-5, a number of coaxial sub-through holes corresponding to the planetary gears 2-2 are provided. The planetary gear shafts 2-3 on the planetary gears 2-2 are respectively rotatably arranged in the corresponding sub-through holes.

[0089] Among them, the above central lead screw 3-1 is coaxially key-connected to the output through hole of the planet carrier 2-5 of the planetary reduction mechanism.

[0090] Among them, the inner side of the above-mentioned internal gear ring 2-4 is rotationally connected to the planet carrier 2-5 through angular contact ball bearings C2-8, and the planet gear shaft 2-3 is rotationally connected to the sub-through hole of the planet carrier 2-5 through angular contact ball bearings B2-7. In this solution, planet carrier retaining rings 2-6 can be respectively arranged on the left and right sides of the angular contact ball bearings C2-8 on the outer side of the planet carrier 2-5 as required. In this solution, the right side of the internal gear ring 2-4 is rotationally connected to the above-mentioned motor rotor 1-3 through angular contact ball bearings A1-7.

[0091] Specifically, the planetary reduction mechanism 2 takes the sun gear 2-1 as the input, the internal gear ring 2-4 is fixed, and the output is carried out through the planet carrier 2-5, with a large reduction ratio. The reduction ratio can be 5.467, or a motor with a smaller power and a smaller volume can be selected for driving; a counterbore can be arranged at the center of the left end of the motor rotor 1-3, and a disc-shaped structure is machined on the sun gear 2-1. The disc-shaped structure of the sun gear 2-1 is connected to the counterbore on the motor rotor 1-3 by screws, so that the sun gear 2-1 and the motor rotor 1-3 rotate coaxially. The internal gear ring 2-4 is fixedly connected to the motor housing 1-1 through bolts passing through. The planet carrier 2-5 is cylindrical, and a total of 4 through holes can be opened inside. One of the through holes is coaxial with the planet carrier 2-5 and serves as an output through hole to cooperate with the central lead screw 3-1. The other three through holes are evenly arranged around the central through hole and serve as sub-through holes for installing the planet gear shafts 2-3 of the planet gears 2-2. The outer periphery of the planet carrier 2-5 is connected to the inner side wall of the internal gear ring 2-4 through a pair of angular contact ball bearings 2-8, ensuring that the planet carrier 2-5 can rotate when the internal gear ring 2-4 is fixed. The planetary reduction mechanism 2 is provided with 3 planet gears 2-2, which are evenly distributed on the planet carrier 2-5. The outer wall of the planet gear shaft 2-3 and the inner wall of the planet hole are rotationally connected through a pair of angular contact ball bearings 2-7, ensuring the movement function of the planet gears 2-2 to revolve and rotate.

[0092] In another specific embodiment based on the above, the right end of the motor housing 1-1 is connected to the clamp body 6 through a circular flange plate 1-4. The flange plate 1-4 extends inwards into the installation groove of the motor rotor 1-3, and a circular thrust bearing 3-4 is provided on the inner wall located in the installation groove, and is rotationally connected to a circular retaining disc 3-5 through the thrust bearing 3-4. The central lead screw 3-1 is in the configuration of a stepped shaft, and the right end of the retaining disc 3-5 abuts against a shoulder of a section of the central lead screw 3-1. In another specific embodiment, the left end of the above-mentioned flange plate 1-4 located in the installation groove can abut against the above-mentioned angular contact ball bearing C2-8.

[0093] Specifically, the central lead screw 3-1 can adopt a stepped shaft configuration and is divided into four sections according to the diameter, with the diameter increasing in sequence. The section of the shaft with the smallest diameter is key-connected to the output through-hole of the planet carrier 2-5, and the surface of the section of the shaft with the largest diameter is machined into a thread; a shoulder of the central lead screw 3-1 abuts against the retaining disk 3-5. A flywheel disk 1-4 is arranged on the right side of the internal gear ring 2-4. The flywheel disk 1-4 and the motor housing 1-1 are fixedly connected through bolts penetrating through. The retaining disk 3-5 and the flywheel disk 1-4 are rotationally connected through a thrust bearing 3-4 to ensure that the retaining disk 3-5 can rotate together with the central lead screw 3-1 when the flywheel disk 1-4 is fixed; a pressure sensor can be installed between the retaining disk 3-5 and the thrust bearing 3-4 to measure the thrust of the braking mechanism 3. In a specific embodiment, during braking, the central lead screw 3-1 is subjected to a leftward thrust. At this time, the thrust bearing 3-4 will first bear the axial force from the retaining disk 3-5 and transmit it to the flywheel disk 1-4 and then to the caliper body 6, prompting the caliper body 6 to move leftward in a floating manner to effectively clamp both sides of the brake disk; when releasing the brake, due to the internal resistance of the planetary roller 3-2 transmission, when the lead screw nut 3-3 retracts, the central lead screw 3-1 will be subjected to a rightward resistance, and this resistance is then transmitted to the planetary reduction mechanism 2, and then transmitted through the angular contact ball bearing B2-7 and the angular contact ball bearing C2-8, and finally the resistance is transmitted to the flywheel disk 1-4. The flywheel disk 1-4 is subjected to a rightward thrust at this time, thereby prompting the caliper body 6 to move rightward, so that the device system can have the function of floating braking.

[0094] That is, when the friction plate on one side of the piston end cover 5 is pressed against the brake disk, the reaction force of the brake disk received by the braking mechanism 3 will cause structures such as the caliper body 6 to move in the opposite direction, so that the caliper body 6 drives the caliper and the friction plate thereon to move in the reverse direction until they are pressed against the other side of the brake disk.

[0095] In another specific embodiment based on the above, a slideway is axially arranged in the inner cavity of the caliper body 6, and the lead screw nut 3-3 and the inner cavity of the caliper body 6 are limited and slidably connected through a guide flat key.

[0096] Specifically, the lead screw nut 3-3 and the slideway of the caliper body 6 can be connected through two 180° guide flat keys. The radial cross-section of the slideway and the outer side wall of the lead screw nut 3-3 is circular; using the guide flat key to connect the lead screw nut 3-3 and the slideway restricts the circumferential rotation of the lead screw nut 3-3, and the lead screw nut 3-3 only makes axial translation to push the piston end cover 5; making the radial cross-section of the slideway and the outer side wall of the lead screw nut 3-3 circular can greatly reduce the probability of the lead screw nut 3-3 getting stuck.

[0097] A control method for the above electro-mechanical braking system of the present invention is specifically as follows:

[0098] First, introduce the EMB control: The electro-mechanical brake is abbreviated as EMB. The key points of EMB control mainly include motor current conversion, motor position control, motor current control, and the EMB control algorithm. Starting from the generation of the driver's braking request, the EMB system converts the desired braking torque into a motor current signal, then precisely adjusts the motor current through the motor current control module to make it follow the desired value, and the motor position control module manages the braking gap. The actual braking force is output by the motor and applied to the brake, and the real-time feedback system continuously monitors the braking state and adjusts parameters to ensure the braking effect. When the braking request is released, the system gradually releases the braking force and ensures the safety and stability of the system through continuous monitoring and diagnosis.

[0099] During the braking process, when the electro-mechanical braking system of the present invention receives a braking signal, the motor mechanism 1 starts to rotate, driving the planetary reduction mechanism 2 and then driving the braking mechanism 3 to push the piston end cover 5. First, the braking gap is overcome. In this process, it is mainly the internal friction of the planetary reduction mechanism 2 and the braking mechanism 3. The friction plate at the piston end cover 5 is not subject to resistance. After the motor rotor 1-3 rotates a certain angle, the friction plate contacts the brake disc, and the motor mechanism 1 will quickly decelerate and enter the stall state. At this time, the motor rotor 1-3 has rotated a certain angle. However, due to the deformation of the braking system, when the friction plate contacts the brake disc, the motor rotor 1-3 will still continue to rotate a certain angle. In this process, the motor mechanism 1 is actually decelerating. After that, the motor rotor 1-3 will maintain the rotation angle and maintain the braking torque. During the process, due to the motor characteristics, the current in the stator winding 1-2 will increase rapidly, and the torque will rise sharply to overcome the load. This transition process from the normal state to the stall state will cause a sudden change in the torque of the motor mechanism 1.

[0100] Considering controlling the current of the motor mechanism 1 to reach the desired current during the control process, the corresponding desired braking torque can be obtained. During the whole process, the motor mechanism 1 experiences three stages: "acceleration - deceleration - stall". After entering the stall state, the current of the motor mechanism 1 will increase significantly, quickly reach the desired current value, and the torque of the motor mechanism 1 will also increase rapidly, which will cause a sharp change in the thrust of the braking mechanism 3. In order to reduce this torque mutation the impact on the braking motor mechanism 1, thereby reducing the variable load borne by the planet carrier 2-5 and the braking mechanism 3 in the present invention, and preventing the screw transmission pair from being stuck due to a large impact, the following control method is provided.

[0101] When the driver performs a braking operation, assuming the braking pedal depth is d and the stepping speed is w, the expected braking intensity of the vehicle obtained therefrom is z. The larger the corresponding pedal depth d, the greater the braking intensity desired by the driver. The magnitude of the stepping speed w can reflect the driver's braking demand, that is, the desire to reduce the vehicle speed or the need for the vehicle to stop urgently; the expected braking intensity z is directly related to the expected braking torque and, without considering the change in tire adhesion characteristics, in order to obtain a greater expected braking intensity z, a greater expected braking torque is required .

[0102] As shown Figure 6 in the appendix, specifically, the braking pedal depth d is collected, which reflects the braking intensity desired by the driver, and the stepping speed w is collected, which reflects the urgency of the driver's braking demand, and input into a preset fuzzy control system. The fuzzy control system outputs the expected braking intensity z; the expected braking intensity z is used as the input of the neural network. The neural network includes a hidden layer and is processed through a non-linear mapping. The training process of the neural network uses historical driving data, optimizes the output result by adjusting the weights, and outputs the optimized expected braking intensity z. This neural network optimization method can adopt conventional techniques;

[0103] According to the optimized expected braking intensity z and vehicle parameters, the expected braking torque is calculated using the formula :

[0104] ;

[0105] where m is the vehicle mass, g is the acceleration due to gravity, is the rolling radius of the vehicle wheel;

[0106] After obtaining the expected braking torque , according to the parameters of the planetary reduction mechanism 2 and the planetary roller 3-2, the relationship between the target current required to be output by the motor mechanism 1 and the required expected braking torque is derived:

[0107] ;

[0108] ;

[0109] ;

[0110] ;

[0111] Then:

[0112] ;

[0113] ;

[0114] In the formula: is the electromagnetic torque, is the number of pole pairs of the motor mechanism 1, is the permanent magnet flux linkage, and are the components of the current in the stator winding 1-2 on the d-axis and q-axis respectively, and are the inductances of the d-axis and q-axis respectively, n is the transmission ratio of the planetary reduction mechanism, is the transmission pair efficiency of the planetary roller 3-2, is the output torque of the planetary reduction mechanism 2, is the clamping force of the braking mechanism 3, is the lead of the central lead screw 3-1, is the effective radius of the brake disc, is the friction coefficient between the friction plate and the brake disc;

[0115] According to the calculation, it is obtained that is used as the target current, and based on the obtained target current, a control signal for the motor mechanism 1 is output. Generally, PI control is used for motor control, and is controlled at 0, so is proportional to , so the target current can be directly determined according to the torque demand.

[0116] Based on the above steps, it further includes:

[0117] Introduce a smoothing coefficient s. After determining the desired braking intensity z and the desired braking torque according to the above steps, on the basis of the set target current and electromagnetic torque control strategy, during the process of the braking mechanism 3 eliminating the braking gap and before the motor mechanism 1 enters the stalled state, the smoothing coefficient s is applied to the torque control of the motor mechanism 1 to improve the target current of the motor mechanism 1. When it is recognized as entering the stalled state, the smoothing coefficient s of the control strategy will be removed. Due to the different desired braking intensities z, the torque of the motor mechanism 1 during the stage of overcoming the braking gap gradually increases with the increase of the desired braking intensity z. Therefore, the smoothing coefficient s should be changed according to the desired braking intensity z, that is, the brake pedal depth d and the stepping speed w. The adhesion coefficient of a good road surface is 0.8. Therefore, a relationship curve between the smoothing coefficient s and the desired braking intensity z can be established. According to the empirical formula, the upper limit of the smoothing coefficient s is set to 1.5 and gradually approaches 1 with the increase of the desired braking intensity z. The following relational expression can be established:

[0118] ;

[0119] ;

[0120] ;

[0121] Then:

[0122] ;

[0123] ;

[0124] According to the calculation, it is obtained that As the improved target current, according to the improved target current, a control signal for the motor mechanism 1 is output.

[0125] Specifically, when the braking mechanism 3 has not completely eliminated the braking gap, that is, before the motor mechanism 1 is about to enter the stall state, the smoothness coefficient s is applied to the current control method of the motor mechanism 1 to increase the output current of the motor mechanism 1. When the motor mechanism 1 is identified as entering the stall state, the smoothness coefficient s will be removed. Compared with the original set control strategy, this method significantly improves the torque of the motor mechanism 1 in the stage of overcoming the braking gap, reduces the gap between the actual output torque and the stall torque of the motor mechanism 1, and shortens the time required to overcome the braking gap, thereby enhancing the response performance of the brake and the smoothness of braking.

[0126] Among them, the processing of the above-mentioned fuzzy control system includes the following steps:

[0127] Formulate a fuzzy set of the input variable 1, the braking pedal depth d ∈ [0, 100]%: {very shallow (VSd), shallow (Sd), medium deep (Md), deep (Ld)}, divide it into four equal parts according to every 25%, and determine the membership function as:

[0128] ;

[0129] ;

[0130] ;

[0131] ;

[0132] Formulate a fuzzy set of the input variable 2, the stepping speed w ∈ [0, 10] cm / s: {very slow (VSw), slow (Sw), medium speed (Mw), fast (Lw)}, divide it into four equal parts according to every 2.5 cm / s, and determine the membership function as:

[0133] ;

[0134] ;

[0135] ;

[0136] ;

[0137] Formulate a fuzzy set for the output variable braking intensity \(Z\in[0,100]\%\): \{Very Small (VSZ), Small (SZ), Medium (MZ), Large (LZ), Very Large (VLZ)\}, divide it into five equal parts according to every 20%, and determine the membership function as:

[0138] ;

[0139] ;

[0140] ;

[0141] ;

[0142] ;

[0143] According to driving experience and vehicle performance, formulate \(i\) fuzzy rules \(R_i\). The principle of the fuzzy rule \(R_i\) is to obtain the corresponding element in the fuzzy set of the braking intensity \(Z\) according to different elements in the fuzzy set of the pedal depth \(d\) and different elements in the fuzzy set of the stepping speed \(w\). Specifically, when the value range of \(i\) is from 1 to 16, the fuzzy rules \(R_i\) are as follows:

[0144] R1: If \(d\) is VSd and \(w\) is VSw, then \(Z\) is VSZ;

[0145] R2: If \(d\) is VSd and \(w\) is Sw, then \(Z\) is SZ;

[0146] R3: If \(d\) is VSd and \(w\) is Mw, then \(Z\) is MZ;

[0147] R4: If \(d\) is VSd and \(w\) is Lw, then \(Z\) is LZ;

[0148] R5: If \(d\) is Sd and \(w\) is VSw, then \(Z\) is SZ;

[0149] R6: If \(d\) is Sd and \(w\) is Sw, then \(Z\) is MZ;

[0150] R7: If \(d\) is Sd and \(w\) is Mw, then \(Z\) is LZ;

[0151] R8: If \(d\) is Sd and \(w\) is Lw, then \(Z\) is VLZ;

[0152] R9: If \(d\) is Md and \(w\) is VSw, then \(Z\) is MZ;

[0153] R10: If \(d\) is Md and \(w\) is Sw, then \(Z\) is LZ;

[0154] R11: If d is Md and w is Mw, then Z is VLZ;

[0155] R12: If d is Md and w is Lw, then Z is VLZ;

[0156] R13: If d is Ld and w is VSw, then Z is LZ;

[0157] R14: If d is Ld and w is Sw, then Z is VLZ;

[0158] R15: If d is Ld and w is Mw, then Z is VLZ;

[0159] R16: If d is Ld and w is Lw, then Z is VLZ;

[0160] Using the fuzzy inference mechanism, reasoning is carried out according to the fuzzified input and fuzzy rules, and for each fuzzy rule Ri, the corresponding activation strength is calculated :

[0161] ;

[0162] where is the membership function output corresponding to the braking pedal depth d in the i-th fuzzy rule, is the membership function output corresponding to the stepping speed w in the i-th fuzzy rule. The value range of Ai is VSd, Sd, Md, and Ld, and the value range of Bi is VSw, Sw, Mw, and Lw;

[0163] Take the result output greater than 0, and the output fuzzy set of each fuzzy rule is trimmed by the activation strength, that is:

[0164] ;

[0165] is the membership function output of the braking strength Z in the i-th fuzzy rule determined by the braking pedal depth d and the stepping speed w. The value range of Ci is VSZ, SZ, MZ, LZ, and VLZ, is the rule output of the i-th fuzzy rule;

[0166] Superimpose all rule outputs:

[0167] ;

[0168] Convert the fuzzy representation of the braking strength Z obtained by fuzzy inference into a specific numerical value, use the discrete centroid method for defuzzification, divide the braking strength Z into h points, and calculate the weighted sum:

[0169] ;

[0170] is the braking intensity percentage, and the defined road condition influence range is [0-a], where a is the road condition coefficient and 0 < a ≤ 1; then, the final expected braking intensity z is z = a.

[0171] Specifically, the braking intensity Z can be divided into 100 points, for example, and the weighted sum is calculated:

[0172] ;

[0173] That is, when h takes 100, the discrete centroid method is used for defuzzification calculation.

[0174] It should be noted that the terms such as "upper", "lower", "left", "right", "front", "rear", etc. cited in the invention are only for the convenience of clear description, rather than used to limit the scope of implementation of the present invention. The change or adjustment of their relative relationship, without substantial change in the technical content, should also be regarded as the scope of implementation of the present invention.

[0175] The above is only the preferred implementation mode of the present invention. The protection scope of the present invention is not limited to the above embodiments. All technical solutions falling within the idea of the present invention belong to the protection scope of the present invention. It should be pointed out that for those of ordinary skill in the art, it can be understood that various changes, modifications, substitutions, refinements and variations can be made to these embodiments without departing from the principles and spirit of the present invention, and it should be regarded as the protection scope of the present invention. The scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A control method for an electro-mechanical braking system, characterized in that: The system includes: a motor mechanism (1), a planetary reduction mechanism (2), a braking mechanism (3), a piston end cover (5) and a caliper body (6). The motor mechanism (1) includes a motor housing (1-1), a stator winding (1-2) and a motor rotor (1-3). The braking mechanism (3) includes a central lead screw (3-1), planetary rollers (3-2) and a lead screw nut (3-3). The motor housing (1-1) is provided with a hollow inner cavity, and the right end is connected to the caliper body (6). The inner cavity of the caliper body (6) is communicated with the motor housing (1-1). A caliper is provided at the right end of the caliper body (6). A circle of stator windings (1-2) is distributed around the inner cavity of the motor housing (1-1). The motor rotor (1-3) is rotatably arranged at the center of the inner cavity of the motor housing (1-1) corresponding to the stator winding (1-2). An installation groove is opened at the right end of the motor rotor (1-3). The planetary reduction mechanism (2) is installed in the installation groove. The input end of the planetary reduction mechanism (2) is connected to the motor rotor (1-3), and the output end of the planetary reduction mechanism (2) is connected to one end of the central lead screw (3-1). The other end of the central lead screw (3-1) extends into the inner cavity of the caliper body (6), and a plurality of planetary rollers (3-2) are wound around and threadedly driven on the outside. A lead screw nut (3-3) is commonly threadedly sleeved on the outside of the plurality of planetary rollers (3-2). The lead screw nut (3-3) is slidably arranged in the inner cavity of the caliper body (6) left and right, and a piston end cover (5) is installed at the right end of the lead screw nut (3-3). The lead screw nut (3-3) is used to drive the piston end cover (5) to move closer to or away from the caliper along the inner cavity of the caliper body (6); The method includes: collecting the braking pedal depth d and the stepping speed w, and inputting them into a preset fuzzy control system, and the fuzzy control system outputs the desired braking intensity z; Calculate the expected braking torque using the formula based on the expected braking intensity z and vehicle parameters : ； where m is the vehicle mass and g is the acceleration due to gravity, is the rolling radius of the vehicle wheel; Obtain the desired braking torque After that, according to the parameters of the planetary reduction mechanism (2) and the planetary roller (3-2), the relationship between the target current required for the output of the motor mechanism (1) and the desired braking torque required is as follows: ； ； ； ； Then: ； ； Wherein: is the electromagnetic torque, is the number of pole pairs of the motor, is the permanent magnet flux linkage, and are respectively the components of the current in the stator winding (1-2) on the d-axis and q-axis, and are respectively the inductances of the d-axis and q-axis, n is the transmission ratio of the planetary reduction mechanism, is the transmission efficiency of the planetary roller (3-2) transmission pair, is the output torque of the planetary reduction mechanism (2), is the clamping force of the braking mechanism (3), is the lead of the central lead screw (3-1), is the effective radius of the brake disc, is the friction coefficient between the friction plate and the brake disc; Based on the calculation, it is obtained that as the target current, and based on the obtained target current, a control signal for the motor mechanism (1) is output.

2. The control method of an electro-mechanical braking system according to claim 1, characterized in that: The left end of the motor housing (1-1) is connected to a left end cover (1-6). The inner side of the left end cover (1-6) is connected with a circle of angular contact ball bearings A (1-7), and the motor rotor (1-3) is rotatably connected through the angular contact ball bearings A (1-7).

3. A control method for an electro-mechanical braking system according to claim 2, characterized in that: A through hole is opened at the center of the left end cover (1-6). The input end of the planetary reduction mechanism (2) passes through the motor rotor (1-3) and extends leftward from the through hole of the left end cover (1-6). An encoder end cover (1-5) is installed on the left side of the through hole of the left end cover (1-6). The space between the encoder end cover (1-5) and the input end of the planetary reduction mechanism (2) is the encoder installation space (7).

4. A control method for an electro-mechanical braking system according to claim 1, characterized in that: The planetary reduction mechanism (2) includes a sun gear (2-1) as the input end, planetary gears (2-2), an internal gear ring (2-4), and a planet carrier (2-5). At the center of the left end face within the mounting groove of the motor rotor (1-3), a sun gear (2-1) coaxial with it is fixedly connected. The end of the sun gear (2-1) located within the mounting groove meshes with a number of equally spaced planetary gears (2-2). The internal gear ring (2-4) is cylindrical and arranged within the mounting groove, and there is a ring of teeth for meshing with the planetary gears (2-2) on the inner side of the left end. The right end is fixedly connected to the right end of the motor housing (1-1). A planet carrier (2-5) coaxial with the sun gear (2-1) is rotatably arranged inside the internal gear ring (2-4). At the center of the planet carrier (2-5), there is an output through hole for fixedly connecting with the central lead screw (3-1). Around the output through hole on the planet carrier (2-5), a number of coaxial sub-through holes corresponding to the planetary gears (2-2) are provided. The planetary gear shafts (2-3) on the planetary gears (2-2) are respectively rotatably arranged in the corresponding sub-through holes.

5. A control method for an electro-mechanical braking system according to claim 4, characterized in that: The inner side of the internal gear ring (2-4) is rotatably connected to the planet carrier (2-5) through an angular contact ball bearing C (2-8), and the planetary gear shafts (2-3) are rotatably connected in the sub-through holes of the planet carrier (2-5) through angular contact ball bearings B (2-7).

6. The control method of an electromechanical braking system according to claim 1, characterized in that: The right end of the motor housing (1-1) is connected to the clamp body (6) through a ring of flanging disks (1-4). The flanging disks (1-4) extend inwards into the mounting groove of the motor rotor (1-3), and there is a ring of thrust bearings (3-4) on the inner wall located in the mounting groove. A retaining disk (3-5) is rotatably connected through the thrust bearings (3-4). The central lead screw (3-1) has a stepped shaft configuration, and the right end of the retaining disk (3-5) abuts against a shoulder of a section of the central lead screw (3-1).

7. A control method for an electro-mechanical braking system according to claim 1, characterized in that: In the inner cavity of the clamp body (6), a slideway is provided axially. The lead screw nut (3-3) is connected with the inner cavity of the clamp body (6) through a guide key for limited sliding connection.

8. A control method for an electro-mechanical braking system according to claim 1, characterized in that, It also includes the following steps: Introduce a stability coefficient s and establish the following relationship: ； ； ； Then: ； ； According to the calculation, it is obtained that As the improved target current, according to the improved target current, a control signal for the motor mechanism (1) is output.

9. The control method of an electro-mechanical braking system according to claim 1, characterized in that, The processing of the fuzzy control system includes the following steps: Divide the input variables into 4 fuzzy sets and the output variables into 5 fuzzy sets; Formulate the fuzzy set of input variable 1, the depth d of the brake pedal ∈ [0, 100]%: {Very Shallow (VSd), Shallow (Sd), Medium Deep (Md), Deep (Ld)}, divide it into four equal parts according to every 25%, and determine the membership function as: ； ； ； ； Formulate the fuzzy set of input variable 2, the stepping speed w ∈ [0, 10] cm / s: {Very Slow (VSw), Slow (Sw), Medium Speed (Mw), Fast (Lw)}, divide it into four equal parts according to every 2.5 cm / s, and determine the membership function as: ； ； ； ； Formulate the fuzzy set of output variable, the braking intensity Z ∈ [0, 100]%: {Very Small (VSZ), Small (SZ), Medium (MZ), Large (LZ), Very Large (VLZ)}, divide it into five equal parts according to every 20%, and determine the membership function as: ； ； ； ； ； According to driving experience and vehicle performance, i fuzzy rules Ri are formulated. The principle of the fuzzy rule Ri is to obtain the corresponding elements in the fuzzy set of braking intensity Z based on different elements in the fuzzy set of pedal depth d and different elements in the fuzzy set of stepping speed w; Using a fuzzy inference mechanism, perform inference based on the fuzzified inputs and fuzzy rules, and for each fuzzy rule Ri, calculate the corresponding activation strength : ； Among them, is the output of the membership function corresponding to the brake pedal depth d in the i-th fuzzy rule, is the output of the membership function corresponding to the stepping speed w in the i-th fuzzy rule. The value range of Ai is VSd, Sd, Md, and Ld, and the value range of Bi is VSw, Sw, Mw, and Lw; The output fuzzy set of each fuzzy rule is clipped by the activation intensity, that is: ； is the membership function output of the braking intensity Z in the i-th fuzzy rule determined by the braking pedal depth d and the stepping speed w. The value range of Ci is VSZ, SZ, MZ, LZ, and VLZ. is the rule output of the i-th fuzzy rule; If the value range of i is from 1 to H, then the outputs of all rules are superimposed: ； Convert the fuzzy representation of the braking intensity Z obtained by fuzzy inference into a specific numerical value. The discrete centroid method is used for defuzzification. The braking intensity Z is divided into h points, and the weighted sum is calculated: ； is the percentage of braking intensity. Define the influence range of road conditions as [0 - a], where a is the road condition coefficient and 0 < a ≤ 1. Then, the final expected braking intensity z is z = a.

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