A brake consistency adjustment method and system for electric tractor

Abstract

The present invention provides a brake consistency adjustment method and system for an electric tractor, which relates to the field of vehicle braking technology. The method includes: determining a critical roll force based on the properties of the tractor; calculating the actual roll force of the tractor in different operating scenarios; combining the translational motion component of the drum brake device, calculating the internal resistance of the drum brake device to the pneumatic device during the piston movement; calculating the thrust of the pneumatic device according to the pressure difference of the pneumatic device; combining the internal resistance and the thrust of the pneumatic device, with the actual roll force after the pneumatic device intervenes being less than the critical roll force as a constraint, determining the target pneumatic device thrust of the brake actuator; using the pneumatic device thrust deviation value as input and the pneumatic device absolute air pressure as output to establish a fractional-order PID controller; adjusting the pneumatic device according to the target pneumatic device absolute air pressure, so that the trailer follows the braking process of the tractor. Improve braking accuracy, avoid brake folding conditions, and improve braking safety.

Description

Technical Field

[0001] The present invention relates to the technical field of vehicle braking, and in particular to a method and system for adjusting the braking consistency of an electric tractor. Background Art

[0002] The braking process of the tractor is that the driver presses the brake pedal to trigger the braking system. First, regenerative braking is used to convert kinetic energy into braking signals. At the same time, the air brake system (mechanical brake) drives the brakes through air pressure, eventually slowing down or stopping the movement of the tractor and trailer. During the whole process, the braking of the tractor and trailer needs to be consistent to ensure driving stability and prevent rollover or loss of control.

[0003] Drum brake equipment is a common vehicle braking system, mainly composed of brake drums, brake shoes, brake cylinders and friction linings. It slows down or stops the movement of the vehicle by pushing the brake shoes outwards so that the friction linings are close to the inner surface of the brake drum, generating friction. Drum brakes are usually used for heavy vehicles such as trucks, tractors and trailers because of their simple structure, low cost and strong durability. They still have good braking effect when a large braking force is required. When the tractor and trailer are braking, due to the difference in load, inertia and turning lateral force, the braking may be uncoordinated, which may lead to dangers such as rollover and skidding. By analyzing the drum brake equipment and adjusting the tractor's brake consistency, it can ensure that the tractor and trailer maintain synchronous braking under various working conditions, improve driving safety and stability, and prevent accidents.

[0004] However, existing braking schemes often do not fully consider the roll force of the tractor itself, but directly use the thrust generated by the trailer during braking as the magnitude of the braking force to provide braking force. They also do not consider the problem that the complex internal structure of the drum brake equipment may cause the actual braking force to be weakened during the braking force transmission process, which leads to the braking force being unable to compensate for the thrust applied to the tractor by the deceleration of the trailer, affecting the smooth operation of the tractor. If the thrust is not restrained during the turning process, when the thrust generates excessive lateral thrust on the tractor, it is very easy to cause the body of the tractor to fold, seriously threatening the operating safety of the tractor. Summary of the invention

[0005] In order to solve the technical problems that the existing braking schemes in the prior art often do not fully consider the roll force of the tractor itself, but directly use the thrust generated by the trailer during braking as the size of the braking force to provide the braking force, and do not consider the problem that the complex internal structure of the drum brake equipment may cause the actual braking force to be weakened during the braking force transmission process, thereby resulting in the braking force being unable to compensate for the thrust applied to the tractor by the deceleration of the trailer, affecting the smooth operation of the tractor, and if the thrust is not constrained during the turning process, when the thrust generates excessive lateral thrust on the tractor, it is very easy to cause the body to fold, seriously threatening the operation safety of the tractor, the present invention provides a brake consistency adjustment method and system for an electric tractor.

[0006] The technical solution provided by the embodiment of the present invention is as follows:

[0007] First aspect

[0008] An electric tractor brake consistency adjustment method provided in an embodiment of the present invention is applied to an air brake platform, wherein the air brake platform includes a pneumatic device and a drum brake device connected by a brake actuator, and the pneumatic device is connected to the drum brake device; the method includes:

[0009] S1: determining a critical roll force when the center of gravity of the tractor exceeds the wheelbase range based on the tractor properties, wherein the tractor properties include the height of the center of gravity of the tractor, the wheelbase of the coaxial wheels of the tractor, and the mass of the tractor;

[0010] S2: Calculate the actual roll force of the tractor under different operation scenarios, where the operation scenarios include turning scenarios and straight driving scenarios;

[0011] S3: Combined with the translational motion components of the drum brake device, calculate the internal resistance of the drum brake device to the pneumatic device during the piston movement, wherein the internal resistance includes the internal viscous friction force of the piston movement, the mechanical resistance and the mechanical motion inhibition force;

[0012] S4: Calculate the thrust of the pneumatic equipment according to the pressure difference of the pneumatic equipment;

[0013] S5: combining the internal resistance and the thrust of the pneumatic device, with the constraint that the actual roll force after the pneumatic device is involved is less than the critical roll force, determining the target pneumatic device thrust of the brake actuator;

[0014] S6: Taking the thrust deviation value of the pneumatic device as input and the absolute air pressure of the pneumatic device as output, a fractional-order PID controller is established to output the target absolute air pressure of the pneumatic device;

[0015] S7: The pneumatic device is adjusted according to the target pneumatic device absolute air pressure so that the trailer follows the braking process of the tractor.

[0016] Second aspect

[0017] An embodiment of the present invention provides a brake consistency adjustment system for an electric tractor, comprising:

[0018] processor;

[0019] A memory having computer-readable instructions stored therein, wherein when the computer-readable instructions are executed by the processor, the method for adjusting the braking consistency of the electric tractor according to the first aspect is implemented.

[0020] The third aspect

[0021] An embodiment of the present invention provides a computer-readable storage medium, on which a computer program is stored. When the program is executed by a processor, the method for adjusting the braking consistency of an electric tractor according to the first aspect is implemented.

[0022] The beneficial effects brought about by the technical solution provided by the embodiment of the present invention include at least:

[0023] In the present invention, the critical roll force of the tractor is first determined based on the height of the center of gravity of the tractor, the wheelbase of the coaxial wheels of the tractor and the mass of the tractor, and then the actual roll force of the tractor itself in various scenarios without the influence of the trailer is considered, which provides a data basis for the subsequent braking of the pneumatic equipment, that is, the actual roll force cannot exceed the critical roll force. In the actual braking analysis process, the complexity of the components inside the drum brake equipment is fully considered, and the resistance generated by the drum brake equipment to the pneumatic equipment such as the internal viscous friction force of the piston movement, mechanical resistance and mechanical movement inhibition force are introduced in the analysis process of the braking force output, and then this part of the resistance is compensated in the process of calculating the braking force. In the actual pneumatic equipment control process, the thrust deviation value of the pneumatic equipment is used as input, and the absolute air pressure of the pneumatic equipment is used as output to establish a fractional-order PID controller, and the target absolute air pressure of the pneumatic equipment is output. By introducing fractional-order integral and differential terms, the controller can better handle nonlinear systems and complex dynamic environments, improve the precise control ability of the pneumatic equipment in the braking system, reduce overshoot, oscillation and other phenomena, and enhance the robustness of the system, which is suitable for complex working conditions. This is to avoid the problem of the brake equipment components weakening the actual braking force during braking, ensure that the braking force output by the pneumatic equipment can meet the actual braking force requirements, avoid the tractor's tilting or folding due to insufficient braking force during braking, and improve the tractor's brake adjustment accuracy, driving stability and safety. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the following briefly introduces the drawings required for use in the description of the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0025] Figure 1 A schematic flow chart of a method for adjusting brake consistency of an electric tractor provided in an embodiment of the present invention;

[0026] Figure 2 A schematic structural diagram of an air brake platform provided in an embodiment of the present invention;

[0027] Figure 3 A schematic structural diagram of a brake consistency adjustment system for an electric tractor provided in an embodiment of the present invention. DETAILED DESCRIPTION

[0028] The technical solution of the present invention is described below in conjunction with the accompanying drawings.

[0029] In the embodiments of the present invention, words such as "exemplarily" and "for example" are used to indicate examples, illustrations or explanations. Any embodiment or design described as "example" in the present invention should not be interpreted as being more preferred or more advantageous than other embodiments or designs. Specifically, the use of the word "example" is intended to present the concept in a specific way. In addition, in the embodiments of the present invention, the meaning expressed by "and / or" can be both, or it can be either of the two.

[0030] In order to make the technical problems, technical solutions and advantages to be solved by the present invention more clear, a detailed description will be given below with reference to the accompanying drawings and specific embodiments.

[0031] Reference Manual Attached Figure 1 , showing a flow chart of a method for adjusting brake consistency of an electric tractor provided in an embodiment of the present invention.

[0032] Reference Manual Attached Figure 2 , showing a schematic structural diagram of an air brake platform provided in an embodiment of the present invention.

[0033] An embodiment of the present invention provides a method for adjusting brake consistency of an electric tractor, which is applied to an air brake platform, wherein the air brake platform includes a pneumatic device and a drum brake device connected by a brake actuator, and the pneumatic device is connected to the drum brake device.

[0034] Among them, the brake actuator is responsible for converting the control signal from the brake system into actual mechanical action, driving the pneumatic equipment to operate and achieve braking. It is a key component for converting control signals into execution actions. Pneumatic equipment uses the pressure of compressed air to push the brake piston to move, generate thrust, drive the brake system, and control the braking effect through changes in air pressure. It is the power source in the brake system. The drum brake device is a mechanical component that specifically implements braking. It uses the piston pushed by the pneumatic device to press the friction plate against the brake drum, generate braking force, slow down or stop the movement of the vehicle, and is the main part of the vehicle's actual braking force.

[0035] The process flow of the electric tractor brake consistency adjustment method may include the following steps:

[0036] S1: Determine the critical roll force when the center of gravity of the tractor exceeds the wheelbase range based on the properties of the tractor.

[0037] Among them, the tractor attributes include the tractor center of gravity height, the tractor coaxial wheel track and the tractor mass.

[0038] Among them, the height of the tractor's center of gravity refers to the height of the vehicle's center of gravity in the vertical direction, which is usually located at the bottom or middle of the vehicle body. The height of the center of gravity affects the stability of the vehicle when turning. The higher the center of gravity, the greater the risk of rollover. The coaxial wheel track of the tractor refers to the distance between the left and right wheels on the same axle. The larger the track, the better the stability of the vehicle because the support width increases. The mass of the tractor refers to the total weight of the tractor, including the body, cargo, etc. The greater the mass, the greater the inertia and roll force generated by the vehicle during driving. The critical roll force refers to the maximum lateral force that the tractor can withstand when turning. When this force is exceeded, the vehicle will roll over.

[0039] Specifically, the center of gravity of a tractor is the center point of the vehicle's weight, located at a certain height of the vehicle, usually between the lower part and the middle part of the vehicle body. The height of the center of gravity affects the vehicle's tilt stability. The higher the center of gravity, the easier it is for the vehicle to tilt or roll over when turning. When the vehicle turns, if the lateral force is large enough, it will cause the center of gravity of the vehicle to shift or tilt. As the center of gravity of the vehicle moves from the center position to the outside, the support force (provided by the contact between the tires and the ground) is concentrated on the outer tires of the vehicle, and the inner tires gradually lose their support. If the lateral force continues to increase, the center of gravity of the vehicle will eventually exceed the support range of the outer tires (i.e., the outer boundary of the wheelbase), at which point the vehicle will lose stability and roll over. When the center of gravity exceeds the range of the wheelbase, it can be understood that part of the weight of the vehicle exceeds the support area that the vehicle can rely on. Since the contact point between the tire and the ground provides vertical support, once the center of gravity exceeds this support area, the support force is not enough to balance the torque brought by the center of gravity, and the vehicle will tilt and eventually roll over.

[0040] The maximum lateral force that a tractor can withstand when turning is calculated by analyzing the basic properties of the tractor. When this force exceeds a certain critical value, the center of gravity of the vehicle will shift outside the supporting wheelbase, causing the vehicle to lose balance and possibly roll over. Therefore, this critical roll force is determined to ensure that the tractor will not roll over under various working conditions.

[0041] In a possible implementation manner, the critical roll force is specifically calculated as follows:

[0042]

[0043] Among them, F lat,min represents the critical roll force, M0 represents the mass of the tractor, g represents the acceleration of gravity, b represents the wheelbase of the tractor coaxial wheel, h cg Indicates the height of the tractor's center of gravity.

[0044] It should be noted that the actual roll force is calculated under critical conditions, and the formula used are the actual physical parameters of the vehicle. This can quickly and accurately estimate the maximum lateral force that different models can withstand when turning, helping engineers optimize the design and improve the safety of tractors, especially in terms of rollover risk control in actual applications.

[0045] Specifically, to calculate the minimum force for the tractor to roll over, it is usually necessary to consider the critical point at which the tractor loses stability and begins to tilt under the action of lateral forces (such as centrifugal force or crosswind when turning). This minimum force depends on the vehicle's center of gravity height, wheelbase, mass and turning radius. The minimum roll force refers to the minimum lateral force (rolling force) that causes the vehicle to begin to roll over.

[0046] It should be noted that when a vehicle is subjected to lateral force, it will tilt and the weight will gradually transfer to the outer wheel. Assuming the wheelbase of the vehicle is b, the weight will gradually transfer from the inner tire to the outer tire during the rollover process. When the vehicle is about to roll, the reaction force of the inner tire is almost zero, and all the weight is concentrated on the outer tire. For this reason, the support width of the vehicle is equivalent to half of the wheelbase (i.e. b / 2). Therefore, the anti-rollover moment is calculated based on the support moment provided by the outer tire.

[0047] S2: Calculate the actual roll force of the tractor under different operating scenarios.

[0048] Among them, the operating scenarios include turning scenarios and straight driving scenarios.

[0049] By calculating the actual roll force of the tractor under different operating conditions, mainly including the lateral force the vehicle bears during turning and straight driving, the stability of the vehicle can be evaluated. This step helps to determine the roll risk of the tractor in real driving scenarios, thereby providing a basis for subsequent adjustments to avoid rollover or other unsafe situations.

[0050] It should be noted that traditional vehicles can ensure that the vehicle will not exceed the critical roll value during normal driving when leaving the factory. However, since the tractor is connected to a trailer, the lateral force or roll force applied to the tractor by the trailer when the tractor brakes may exceed the critical roll force. Therefore, it is necessary to consider scenes such as turning and determine the amount of air injected into the brake actuator to avoid the lateral force applied by the trailer and the vehicle itself exceeding the critical roll value during turning, so as to avoid the folding phenomenon that may occur during the braking process of the tractor.

[0051] In a possible implementation manner, the actual roll force is calculated as follows:

[0052]

[0053] F c =M1×a1×cos(α-90)

[0054] Among them, F lat,act Indicates the actual rolling force, represents the lateral acceleration of the tractor, r represents the yaw rate of the tractor, i.e., the rotation speed of the tractor around the vertical axis of the tractor when turning, v represents the speed of the tractor, α represents the angle between the tractor and the trailer, and F c It represents the roll force exerted by the trailer on the tractor, a1 represents the acceleration of the trailer, M1 represents the mass of the trailer, and R represents the turning radius.

[0055] It should be noted that this method of calculating the actual roll force can fully reflect the force conditions of the tractor and trailer under actual working conditions by combining the lateral acceleration, speed, turning radius of the tractor and the roll force applied by the trailer. The formula also introduces the angle between the tractor and the trailer to accurately simulate the lateral impact of the trailer on the tractor. It can simultaneously consider the speed, trailer weight and dynamic movement of the tractor, provide accurate roll force calculation, help optimize braking control in different driving scenarios, and improve the safety and stability of vehicle driving.

[0056] S3: Combined with the translational motion components of the drum brake device, calculate the internal resistance of the drum brake device to the pneumatic device during the piston movement.

[0057] Among them, the internal resistance includes the internal viscous friction force of the piston movement, mechanical resistance and mechanical motion inhibition force.

[0058] Among them, it refers to the part of the drum brake device that moves in a straight line, including the piston, push rod, return spring and diaphragm, which work together to complete the braking process. Internal resistance refers to the obstruction to the movement of the piston in the drum brake device, including factors such as friction and mechanical inhibition. The internal viscous friction of the piston movement is the resistance caused by fluid or surface friction when the piston moves in the cylinder, and is proportional to the movement speed of the piston. Mechanical resistance is the resistance caused by contact, friction and other factors between the piston and other mechanical parts during movement. Mechanical motion inhibition refers to the inhibition or reaction force caused by the elastic or rigid structure within the system on the mechanical movement.

[0059] It should be noted that by accurately calculating the internal resistance of the piston in the drum brake device, including viscous friction, mechanical resistance and motion inhibition, the performance of the brake system can be more comprehensively evaluated. This makes the brake adjustment more precise, avoiding poor braking effect or excessive wear of the brake system due to ignoring the internal resistance, thereby improving the overall efficiency and service life of the system, while ensuring the braking safety and stability of the vehicle under different working conditions.

[0060] In a possible implementation, the translation motion assembly includes a piston, a push rod, a return spring, and a diaphragm.

[0061] In a possible implementation, the internal viscous friction force is specifically:

[0062]

[0063] Among them, F v represents the internal viscous friction, x represents the piston stroke, t represents the piston travel time, k v Indicates the internal viscous friction coefficient of a drum brake system.

[0064] It should be noted that this formula explains that when the piston moves, it will be subject to a force due to friction, and this force is proportional to the speed of the piston. Directly linking the friction force to the movement speed of the piston can accurately reflect the dynamic relationship between the friction force and the speed change. The ability to accurately calculate the friction force in real time helps to optimize brake performance, improve the response speed and stability of the system, and effectively avoid brake failure or wear caused by excessive friction, especially in complex working conditions.

[0065] The mechanical resistance is:

[0066] F T =A e ×{p avr (x pos )±[C0+C1p avr (x pos )]}·10 5

[0067]

[0068] Among them, A e Indicates the effective area of ​​the brake actuator that is subject to the pressure of the pneumatic equipment, D c Indicates the cylinder diameter of pneumatic equipment, D p represents the piston diameter, C0 represents the friction constant that is independent of the piston motion restraining force, i.e., the inherent friction force, C1 represents the friction coefficient between the piston and the cylinder, and x max represents the maximum displacement of the piston, x0 represents the initial position of the piston, i.e. the position of the piston when the pneumatic equipment is not working, F T Indicates that the piston is at position x in the cylinder pos That is, the distance relative to x0 is ( x pos -x 0) The active mechanical resistance generated by the drum brake system at the time of avr (x pos ) represent the piston position at x pos The average pressure generated by the drum brake system at this time, x0 represents the initial position of the piston, x L The piston position, p0 and p, represents the transition from linear to nonlinear pressure generated by the drum brake system. L Represent x0 and x respectively L The pressure generated by the drum brake system, n avr A non-linear index that represents the pressure generated by a drum brake system.

[0069] It should be noted that the calculation formula of this mechanical resistance combines multiple parameters such as cylinder diameter, piston stroke, friction coefficient and piston position. Its advantage is that it can accurately reflect the friction and pressure changes of the piston in different positions and states. In this way, the mechanical resistance of the piston during braking can be simulated more accurately, thereby optimizing the design and control of the braking system and improving the stability and efficiency of the overall braking effect.

[0070] The mechanical motion restraint force is specifically:

[0071]

[0072] Among them, F m Represents the mechanical motion restraint force, m red Indicates the simplified mass of the drum brake equipment, m a and m l are the mass simplified to the piston and the mass of the connector, respectively. The connector is the connecting rod connecting the push rod and the extension rod. J e represents the moment of inertia of the extension rod, J c Represents the moment of inertia of the expansion axis, R cIndicates the radius of the involute cam, R s Indicates the rotation radius of the brake shoe, J s Represents the moment of inertia of the brake shoe, R e Indicates the length of the extension rod, m s Indicates the mass of the return spring, m m Indicates the mass of the diaphragm, m p Represents the total mass of the piston and the connecting rod, where the expansion shaft is the connecting rod connecting the expansion shaft and the involute cam.

[0073] It should be noted that this calculation method of mechanical motion restraining force can accurately describe the inertia and resistance of mechanical components during braking by comprehensively considering multiple factors such as simplified mass, inertia, wheel radius, etc. Its advantage is that it can fully reflect the impact of various components in the mechanical system on the braking process, thereby improving the dynamic control accuracy of complex mechanical systems and ensuring that the system maintains good stability and braking performance under high speed or load changes.

[0074] S4: Calculate the thrust of the pneumatic equipment based on the pressure difference of the pneumatic equipment.

[0075] It should be noted that the thrust generated by the pneumatic device is determined by calculating the pressure difference between the inside and outside of the pneumatic device. Specifically, the pressure inside the pneumatic device pushes the piston outward, forming a thrust that drives the brake system to work. The greater the pressure difference, the greater the thrust, and vice versa. The key to this step is to accurately calculate the thrust of the pneumatic device to ensure that the brake can provide appropriate braking force under different working conditions to ensure the safe braking effect of the vehicle.

[0076] In a possible implementation manner, the thrust of the pneumatic device is calculated as follows:

[0077] F p =A e (pp a )

[0078] Among them, F p Indicates the thrust of pneumatic equipment, that is, the thrust generated by the movement of the piston of pneumatic equipment, A e Represents the effective area of ​​the brake actuator, p a represents the absolute atmospheric pressure, and p represents the absolute air pressure of pneumatic equipment.

[0079] It should be noted that calculating the thrust of pneumatic equipment by combining the effective area of ​​the equipment and the air pressure difference is concise and effective and can accurately reflect the thrust generated by the pneumatic equipment under different pressure conditions. It has strong adaptability and can accurately adjust the output force of the pneumatic equipment, which helps to optimize the braking process and improve the response efficiency and stability of the overall system.

[0080] S5: Combine the internal resistance and the pneumatic device thrust, and determine the target pneumatic device thrust of the brake actuator with the constraint that the actual roll force after the pneumatic device intervenes is less than the critical roll force.

[0081] It should be noted that the precise thrust required when braking the tractor is determined based on the thrust of the pneumatic device and the internal resistance. It compares the actual roll force after the pneumatic device intervenes with the critical roll force to ensure that the actual roll force is always below the critical value to avoid the vehicle rolling over. The purpose of this step is to calculate the target pneumatic device thrust of the brake actuator to ensure that the pneumatic device does not exceed the vehicle's roll safety limit while providing sufficient braking force, thereby improving the stability and safety of the tractor and trailer during braking.

[0082] In a possible implementation manner, the target pneumatic equipment thrust is specifically:

[0083] F′ p =F p -(F v +F T +F m )

[0084] F′ lat,act <F lat,min

[0085]

[0086] F′ c =M1×a1×cos(α-90)-F′ p

[0087] Among them, F′ p Indicates the thrust of the target pneumatic equipment, F′ lat,act Indicates the actual roll force after the pneumatic device intervenes, F′ c It indicates the rolling force exerted by the trailer on the tractor after the pneumatic equipment intervenes.

[0088] It should be noted that the actual roll force, the roll effect of the trailer on the tractor, internal friction and mechanical resistance are taken into consideration. This comprehensive calculation ensures that the thrust can be accurately adjusted to avoid excessive or insufficient braking, improve the stability and safety of the system under various working conditions, and effectively prevent the risk of rollover and brake failure.

[0089] S6: A fractional-order PID controller is established with the thrust deviation value of the pneumatic device as input and the absolute air pressure of the pneumatic device as output, and the target absolute air pressure of the pneumatic device is output.

[0090] Among them, the fractional-order PID controller is a controller that expands the concept of the traditional PID (proportional-integral-differential) controller. The fractional-order PID allows the integral and differential terms to adopt fractional orders.

[0091] It should be noted that the thrust deviation value of the pneumatic equipment (i.e., the difference between the target thrust and the actual thrust) is used as input to calculate the absolute air pressure required by the pneumatic equipment through the fractional-order PID controller to control the thrust output by the pneumatic equipment. The advantage of the fractional-order PID controller is its flexibility and accuracy, which can ensure that the pressure output by the pneumatic equipment is more stable and adapt to complex working conditions, thereby making the braking process of the tractor and trailer more stable and safe, and avoiding overshoot and oscillation.

[0092] In a possible implementation, S6 specifically includes:

[0093] S601: Calculate the thrust deviation of pneumatic equipment:

[0094] e(t)=F′ p2 (t)-F′ p1 (t)

[0095] Where e(t) represents the thrust deviation value of the pneumatic equipment at time t, F′ p1 (t) and F′ p2 (t) represent the target pneumatic equipment thrust at time t and the actual pneumatic equipment thrust at time t respectively.

[0096] S602: Using the pneumatic equipment thrust deviation value as input and the pneumatic equipment absolute air pressure as output, a fractional-order PID controller is established:

[0097] u(t)=K p e(t)+K i D -λ e(t)+K d D μ e(t)

[0098] Among them, u(t) represents the output at time t, that is, the absolute air pressure of the pneumatic equipment at time t, K p , K i , K d Respectively represent proportional gain, integral gain and differential gain, D -λ represents the fractional integral term based on the integral order λ, 0<λ<1, D μ Represents the fractional differential term based on the differential order μ, 0<μ<1.

[0099] It should be noted that it adjusts the thrust deviation output target pneumatic equipment absolute air pressure through a fractional-order PID controller, and can dynamically adjust the pressure output of the pneumatic equipment according to the actual working conditions. Compared with traditional control methods, fractional-order PID control can more finely control the air pressure change, make the system response more sensitive and stable, avoid over-adjustment or under-adjustment, improve the stability and accuracy of the braking system, and ensure the safety of the braking process of the tractor and trailer.

[0100] S7: The pneumatic device is adjusted according to the target pneumatic device absolute air pressure so that the trailer follows the braking process of the tractor.

[0101] In actual use, the maximum roll force of the tractor when turning is calculated by analyzing the center of gravity height, wheelbase and mass of the tractor. Next, the actual roll force of the tractor under different driving scenarios is considered, and the resistance in the drum brake equipment and the thrust generated by the pneumatic equipment are calculated. Then, it is ensured that the thrust of the pneumatic equipment does not cause the vehicle to exceed the roll critical value to ensure safety. Finally, the pressure of the pneumatic equipment is adjusted through the fractional-order PID controller to synchronize the braking process of the tractor and trailer. The entire process ensures the braking coordination of the tractor and trailer under complex working conditions by accurately calculating the roll force and braking force, avoiding rollover and wear, and improving driving safety and braking efficiency.

[0102] The beneficial effects brought about by the technical solution provided by the embodiment of the present invention include at least:

[0103] In the present invention, the critical roll force of the tractor is first determined based on the height of the center of gravity of the tractor, the wheelbase of the coaxial wheels of the tractor and the mass of the tractor, and then the actual roll force of the tractor itself in various scenarios without the influence of the trailer is considered, which provides a data basis for the subsequent braking of the pneumatic equipment, that is, the actual roll force cannot exceed the critical roll force. In the actual braking analysis process, the complexity of the components inside the drum brake equipment is fully considered, and the resistance generated by the drum brake equipment to the pneumatic equipment such as the internal viscous friction force of the piston movement, mechanical resistance and mechanical movement inhibition force are introduced in the analysis process of the braking force output, and then this part of the resistance is compensated in the process of calculating the braking force. In the actual pneumatic equipment control process, the thrust deviation value of the pneumatic equipment is used as input, and the absolute air pressure of the pneumatic equipment is used as output to establish a fractional-order PID controller, and the target absolute air pressure of the pneumatic equipment is output. By introducing fractional-order integral and differential terms, the controller can better handle nonlinear systems and complex dynamic environments, improve the precise control ability of the pneumatic equipment in the braking system, reduce overshoot, oscillation and other phenomena, and enhance the robustness of the system, which is suitable for complex working conditions. This is to avoid the problem of the brake equipment components weakening the actual braking force during braking, ensure that the braking force output by the pneumatic equipment can meet the actual braking force requirements, avoid the tractor's tilting or folding due to insufficient braking force during braking, and improve the tractor's brake adjustment accuracy, driving stability and safety.

[0104] Reference Manual Attached Figure 3 , showing a schematic structural diagram of a brake consistency adjustment system for an electric tractor provided by the present invention.

[0105] The present invention further provides an electric tractor brake consistency adjustment system 20, which is applied to the above-mentioned electric tractor brake consistency adjustment method, comprising:

[0106] Processor 201.

[0107] The memory 202 stores computer-readable instructions. When the computer-readable instructions are executed by the processor 201, the electric tractor braking consistency adjustment method of the method embodiment is implemented.

[0108] The electric tractor brake consistency adjustment system 20 provided by the present invention can execute the above-mentioned electric tractor brake consistency adjustment method and achieve the same or similar technical effects. To avoid repetition, the present invention will not elaborate on them.

[0109] The beneficial effects brought about by the technical solution provided by the embodiment of the present invention include at least:

[0110] In the present invention, the critical roll force of the tractor is first determined based on the height of the center of gravity of the tractor, the wheelbase of the coaxial wheels of the tractor and the mass of the tractor, and then the actual roll force of the tractor itself in various scenarios without the influence of the trailer is considered, which provides a data basis for the subsequent braking of the pneumatic equipment, that is, the actual roll force cannot exceed the critical roll force. In the actual braking analysis process, the complexity of the components inside the drum brake equipment is fully considered, and the resistance generated by the drum brake equipment to the pneumatic equipment such as the internal viscous friction force of the piston movement, mechanical resistance and mechanical movement inhibition force are introduced in the analysis process of the braking force output, and then this part of the resistance is compensated in the process of calculating the braking force. In the actual pneumatic equipment control process, the thrust deviation value of the pneumatic equipment is used as input, and the absolute air pressure of the pneumatic equipment is used as output to establish a fractional-order PID controller, and the target absolute air pressure of the pneumatic equipment is output. By introducing fractional-order integral and differential terms, the controller can better handle nonlinear systems and complex dynamic environments, improve the precise control ability of the pneumatic equipment in the braking system, reduce overshoot, oscillation and other phenomena, and enhance the robustness of the system, which is suitable for complex working conditions. This is to avoid the problem of the brake equipment components weakening the actual braking force during braking, ensure that the braking force output by the pneumatic equipment can meet the actual braking force requirements, avoid the tractor's tilting or folding due to insufficient braking force during braking, and improve the tractor's brake adjustment accuracy, driving stability and safety.

[0111] It should be understood that the processor in the embodiment of the present invention may be a central processing unit (CPU), and the processor may also be other general-purpose processors, digital signal processors (DSP), application specific integrated circuits (ASIC), field programmable gate arrays (FPGA) or other programmable logic devices, discrete gate or transistor logic devices, discrete hardware components, etc. The general-purpose processor may be a microprocessor or the processor may also be any conventional processor, etc.

[0112] It should also be understood that the memory in the embodiments of the present invention may be a volatile memory or a non-volatile memory, or may include both volatile and non-volatile memories. Among them, the non-volatile memory may be a read-only memory (ROM), a programmable read-only memory (PROM), an erasable programmable read-only memory (EPROM), an electrically erasable programmable read-only memory (EEPROM), or a flash memory. The volatile memory may be a random access memory (RAM), which is used as an external cache. By way of example and not limitation, many forms of random access memory (RAM) are available, such as static RAM (SRAM), dynamic random access memory (DRAM), synchronous DRAM (SDRAM), double data rate synchronous dynamic random access memory (DDR SDRAM), enhanced synchronous dynamic random access memory (ESDRAM), synchronous link DRAM (SLDRAM), and direct RAM bus random access memory (DR RAM).

[0113] The above embodiments can be implemented in whole or in part by software, hardware (such as circuits), firmware or any other combination. When implemented by software, the above embodiments can be implemented in whole or in part in the form of a computer program product. The computer program product includes one or more computer instructions or computer programs. When the computer instructions or computer programs are loaded or executed on a computer, the process or function described in the embodiment of the present invention is generated in whole or in part. The computer can be a general-purpose computer, a special-purpose computer, a computer network, or other programmable device. The computer instructions can be stored in a computer-readable storage medium, or transmitted from one computer-readable storage medium to another computer-readable storage medium. For example, the computer instructions can be transmitted from one website, computer, server or data center to another website, computer, server or data center by wired (such as infrared, wireless, microwave, etc.). The computer-readable storage medium can be any available medium that can be accessed by a computer or a data storage device such as a server or data center that contains one or more available media sets. The available medium can be a magnetic medium (for example, a floppy disk, a hard disk, a tape), an optical medium (for example, a DVD), or a semiconductor medium. The semiconductor medium can be a solid-state hard disk.

[0114] It should be understood that the term "and / or" in this article is only a description of the association relationship of associated objects, indicating that there can be three relationships. For example, A and / or B can represent: A exists alone, A and B exist at the same time, and B exists alone. A and B can be singular or plural. In addition, the character " / " in this article generally indicates that the associated objects before and after are in an "or" relationship, but it may also indicate an "and / or" relationship. Please refer to the context for specific understanding.

[0115] In the present invention, "at least one" means one or more, and "more than one" means two or more. "At least one of the following" or similar expressions refers to any combination of these items, including any combination of single or plural items. For example, at least one of a, b, or c can be represented by: a, b, c, ab, ac, bc, or abc, where a, b, c can be single or multiple.

[0116] It should be understood that in various embodiments of the present invention, the size of the serial numbers of the above-mentioned processes does not mean the order of execution. The execution order of each process should be determined by its function and internal logic, and should not constitute any limitation on the implementation process of the embodiments of the present invention.

[0117] Those skilled in the art will appreciate that the units and algorithm steps of each example described in conjunction with the embodiments disclosed herein can be implemented in electronic hardware, or a combination of computer software and electronic hardware. Whether these functions are performed in hardware or software depends on the specific application and design constraints of the technical solution. Professional and technical personnel can use different methods to implement the described functions for each specific application, but such implementation should not be considered to be beyond the scope of the present invention.

[0118] Those skilled in the art can clearly understand that, for the convenience and brevity of description, the specific working processes of the above-described equipment, devices and units can refer to the corresponding processes in the aforementioned method embodiments and will not be repeated here.

[0119] In the several embodiments provided by the present invention, it should be understood that the disclosed devices, apparatuses and methods can be implemented in other ways. For example, the device embodiments described above are only schematic. For example, the division of the units is only a logical function division. There may be other division methods in actual implementation, such as multiple units or components can be combined or integrated into another device, or some features can be ignored or not executed. Another point is that the mutual coupling or direct coupling or communication connection shown or discussed can be through some interfaces, indirect coupling or communication connection of devices or units, which can be electrical, mechanical or other forms.

[0120] The units described as separate components may or may not be physically separated, and the components shown as units may or may not be physical units, that is, they may be located in one place or distributed on multiple network units. Some or all of the units may be selected according to actual needs to achieve the purpose of the solution of this embodiment.

[0121] In addition, each functional unit in each embodiment of the present invention may be integrated into one processing unit, or each unit may exist physically separately, or two or more units may be integrated into one unit.

[0122] If the functions are implemented in the form of software functional units and sold or used as independent products, they can be stored in a computer-readable storage medium. Based on this understanding, the technical solution of the present invention can be essentially or partly embodied in the form of a software product that contributes to the prior art. The computer software product is stored in a storage medium and includes several instructions for enabling a computer device (which can be a personal computer, a server, or a network device, etc.) to perform all or part of the steps of the methods described in various embodiments of the present invention. The aforementioned storage media include: U disk, mobile hard disk, read-only memory (ROM), random access memory (RAM), magnetic disk or optical disk, etc., various media that can store program codes.

[0123] An embodiment of the present invention provides a computer-readable storage medium having a computer program stored thereon. When the program is executed by a processor, the method for adjusting the braking consistency of an electric tractor vehicle as described in the method embodiment is implemented.

[0124] A computer-readable storage medium provided by the present invention can implement the steps and effects of the electric tractor brake consistency adjustment method of the above method embodiment. To avoid repetition, the present invention will not go into details.

[0125] The beneficial effects brought about by the technical solution provided by the embodiment of the present invention include at least:

[0126] In the present invention, the critical roll force of the tractor is first determined based on the height of the center of gravity of the tractor, the wheelbase of the coaxial wheels of the tractor and the mass of the tractor, and then the actual roll force of the tractor itself in various scenarios without the influence of the trailer is considered, which provides a data basis for the subsequent braking of the pneumatic equipment, that is, the actual roll force cannot exceed the critical roll force. In the actual braking analysis process, the complexity of the components inside the drum brake equipment is fully considered, and the resistance generated by the drum brake equipment to the pneumatic equipment such as the internal viscous friction force of the piston movement, mechanical resistance and mechanical movement inhibition force are introduced in the analysis process of the braking force output, and then this part of the resistance is compensated in the process of calculating the braking force. In the actual pneumatic equipment control process, the thrust deviation value of the pneumatic equipment is used as input, and the absolute air pressure of the pneumatic equipment is used as output to establish a fractional-order PID controller, and the target absolute air pressure of the pneumatic equipment is output. By introducing fractional-order integral and differential terms, the controller can better handle nonlinear systems and complex dynamic environments, improve the precise control ability of the pneumatic equipment in the braking system, reduce overshoot, oscillation and other phenomena, and enhance the robustness of the system, which is suitable for complex working conditions. This is to avoid the problem of the brake equipment components weakening the actual braking force during braking, ensure that the braking force output by the pneumatic equipment can meet the actual braking force requirements, avoid the problem of the tractor tipping or folding due to insufficient braking force during braking, and improve the brake adjustment accuracy, driving stability and safety of the tractor.

[0127] The above is only a specific embodiment of the present invention, but the protection scope of the present invention is not limited thereto. Any person skilled in the art can easily think of changes or substitutions within the technical scope disclosed by the present invention, which should be included in the protection scope of the present invention. Therefore, the protection scope of the present invention should be based on the protection scope of the claims.

[0128] There are a few points to note:

[0129] (1) The drawings of the embodiments of the present invention only relate to the structures related to the embodiments of the present invention, and other structures may refer to the general design.

[0130] (2) For the sake of clarity, in the drawings used to describe the embodiments of the present invention, the thickness of the layers or regions is exaggerated or reduced, that is, these drawings are not drawn according to the actual scale. It is understood that when an element such as a layer, film, region or substrate is referred to as being "on" or "under" another element, the element may be "directly" "on" or "under" the other element or there may be intermediate elements.

[0131] (3) In the absence of conflict, the embodiments of the present invention and the features therein may be combined with each other to obtain new embodiments.

[0132] The above are only specific embodiments of the present invention, but the protection scope of the present invention is not limited thereto. The protection scope of the present invention shall be based on the protection scope of the claims.

Claims

1. A method for adjusting the braking consistency of an electric tractor, characterized in that: Applied to an air brake platform, wherein the air brake platform comprises a pneumatic device and a drum brake device connected via a brake actuator, the pneumatic device being connected to the drum brake device; the method comprises: S1: determining a critical roll force when the center of gravity of the tractor exceeds the wheelbase range based on the tractor attributes, wherein the tractor attributes include the height of the center of gravity of the tractor, the wheelbase of the coaxial wheels of the tractor, and the mass of the tractor; S2: Calculating the actual roll force of the tractor in different operation scenarios, wherein the operation scenarios include a turning scenario and a straight driving scenario; S3: combining the translational motion component of the drum brake device, calculating the internal resistance of the drum brake device to the pneumatic device during the piston movement, wherein the internal resistance includes the internal viscous friction force of the piston movement, the mechanical resistance and the mechanical motion inhibition force; S4: Calculate the thrust of the pneumatic equipment according to the pressure difference of the pneumatic equipment; S5: Determine a target pneumatic device thrust of the brake actuator by combining the internal resistance and the pneumatic device thrust, with the actual roll force after the pneumatic device intervenes being less than the critical roll force as a constraint; S6: Taking the thrust deviation value of the pneumatic device as input and the absolute air pressure of the pneumatic device as output, a fractional-order PID controller is established to output the target absolute air pressure of the pneumatic device; S7: adjusting the pneumatic device according to the target pneumatic device absolute air pressure so that the trailer follows the braking process of the tractor.

2. The electric tractor braking consistency adjustment method according to claim 1 is characterized in that: The critical roll force is specifically calculated as follows: Among them, F lat,min represents the critical roll force, M0 represents the mass of the tractor, g represents the acceleration of gravity, b represents the wheelbase of the tractor coaxial wheel, h cg Indicates the height of the tractor's center of gravity.

3. The method for adjusting the braking consistency of an electric tractor according to claim 1, characterized in that: The actual roll force is calculated as follows: F c =M1×a1×cos(α-90) Among them, F lat,act Indicates the actual rolling force, represents the lateral acceleration of the tractor, r represents the yaw rate of the tractor, i.e., the rotation speed of the tractor around the vertical axis of the tractor when turning, v represents the speed of the tractor, α represents the angle between the tractor and the trailer, and F c It represents the roll force exerted by the trailer on the tractor, a1 represents the acceleration of the trailer, M1 represents the mass of the trailer, and R represents the turning radius.

4. The electric tractor braking consistency adjustment method according to claim 1, characterized in that: The translational motion assembly comprises a piston, a push rod, a return spring and a diaphragm.

5. The method for adjusting the braking consistency of an electric tractor according to claim 4, characterized in that: The internal viscous friction force is specifically: Among them, F v represents the internal viscous friction, x represents the piston stroke, t represents the piston travel time, k v Indicates the internal viscous friction coefficient of the drum brake system; The mechanical resistance is specifically: F T =A e ×{p avr (x pos )±[C0+C1p avr (x pos )]}·10 5 Among them, A e Indicates the effective area of ​​the brake actuator that is subject to the pressure of the pneumatic equipment, D c Indicates the cylinder diameter of pneumatic equipment, D p represents the piston diameter, C0 represents the friction constant that is independent of the piston motion restraining force, i.e., the inherent friction force, C1 represents the friction coefficient between the piston and the cylinder, and x max represents the maximum displacement of the piston, x0 represents the initial position of the piston, i.e. the position of the piston when the pneumatic equipment is not working, F T Indicates that the piston is at position x in the cylinder pos That is, the distance relative to x0 is ( x pos -x 0) The active mechanical resistance generated by the drum brake system at the time of avr (x pos ) represent the piston position at x pos The average pressure generated by the drum brake system at this time, x0 represents the initial position of the piston, x L The piston position, p0 and p, represents the transition from linear to nonlinear pressure generated by the drum brake system. L Represent x0 and x respectively L The pressure generated by the drum brake system, n avr A non-linear index representing the pressure generated by a drum brake system; The mechanical motion restraining force is specifically: Among them, F m Represents the mechanical motion restraint force, m red Indicates the simplified mass of the drum brake equipment, m a and m l are the mass simplified to the piston and the mass of the connector, respectively. The connector is the connecting rod connecting the push rod and the extension rod. J e represents the moment of inertia of the extension rod, J c Represents the moment of inertia of the expansion axis, R c Indicates the radius of the involute cam, R s Indicates the rotation radius of the brake shoe, J s Represents the moment of inertia of the brake shoe, R e Indicates the length of the extension rod, m s Indicates the mass of the return spring, m m Indicates the mass of the diaphragm, m p Represents the total mass of the piston and the connecting rod, where the expansion shaft is the connecting rod connecting the expansion shaft and the involute cam.

6. The method for adjusting the braking consistency of an electric tractor according to claim 1, characterized in that: The specific calculation method of the thrust of the pneumatic equipment is: F p =A e (p-p a ) Among them, F p Indicates the thrust of pneumatic equipment, that is, the thrust generated by the movement of the piston of pneumatic equipment, A e Represents the effective area of ​​the brake actuator, p a represents the absolute atmospheric pressure, and p represents the absolute air pressure of pneumatic equipment.

7. The method for adjusting the brake consistency of an electric tractor according to claim 1, characterized in that: The target pneumatic equipment thrust is specifically: F’ p =F p -(F v +F T +F m ) F’ lat,act <F lat,min F' c =M1×a1×cos(α-90)-F' p Among them, F' p Indicates the target pneumatic equipment thrust, F' lat,act Indicates the actual roll force after the pneumatic device intervenes, F c 'Indicates the roll force applied by the trailer to the tractor after the pneumatic device intervenes.

8. The method for adjusting the brake consistency of an electric tractor according to claim 7, characterized in that: The S6 specifically includes: S601: Calculate the thrust deviation value of the pneumatic equipment: e(t)=F’ p2 (t)-F’ p1 (t) Where e(t) represents the thrust deviation value of the pneumatic equipment at time t, F' p1 (t) and F' p2 (t) represents the target thrust of the pneumatic equipment at time t and the actual thrust of the pneumatic equipment at time t respectively; S602: Taking the thrust deviation value of the pneumatic device as input and the absolute air pressure of the pneumatic device as output, establish the fractional-order PID controller: u(t)=K p e(t)+K i D -λ e(t)+K d D μ e(t) Among them, u(t) represents the output at time t, that is, the absolute air pressure of the pneumatic equipment at time t, K p , K i , K d Represents proportional gain, integral gain and differential gain respectively, D -λ represents the fractional integral term based on the integral order λ, 0<λ<1, D μ Represents the fractional differential term based on the differential order μ, 0<μ<1.

9. A brake consistency adjustment system for an electric tractor, characterized in that: include: processor; A memory having computer-readable instructions stored thereon, wherein when the computer-readable instructions are executed by the processor, the method for adjusting the braking consistency of the electric tractor according to any one of claims 1 to 8 is implemented.

10. A computer-readable storage medium having a computer program stored thereon, characterized in that: When the program is executed by a processor, the electric tractor braking consistency adjustment method according to any one of claims 1 to 8 is implemented.

Images