A shift control method, device and equipment for adaptive hill road conditions and a medium

Abstract

The application discloses a kind of adaptive slope road condition gear shift control method, device, equipment and medium, it is related to gear shift control technical field, including the following steps: obtaining slope data and vehicle data, analysis demand wheel end torque, and with power source available torque curve and target working speed as constraint first transmission ratio is deduced back;Based on vehicle demand longitudinal force, eliminate transmission ratio binding engine braking force, and combine brake system regenerative constraint and rate constraint distribution first hydraulic braking force;A number of gear shift control groups are generated by Monte Carlo random sampling, and the enumerated control group is obtained according to the relationship between gear shift control group and demand longitudinal force;Simulate the enumerated control group, evaluate effect, build gear shift control group and evaluation result coordinate system, select appropriate control combined with slope type, and the transmission ratio is mapped to gear position application, adaptive gear shift control is realized, solves the brake control problem that energy efficiency, safety and comfort are considered in vehicle under different slope road conditions.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of gear shift control, and more particularly to a gear shift control method and device for adaptive hill road conditions, equipment and medium. BACKGROUND

[0002] In the power control system of modern electric vehicles, the adjustment of gear position (transmission ratio) is the core link of power transmission and driving stability, and its fundamental purpose is to achieve effective control of the vehicle's longitudinal force. As an essential dynamic variable of the vehicle along the driving direction, the longitudinal force is not only constrained by the road adhesion condition, but also affected by the motor output, transmission ratio selection and brake force distribution. Under hill road conditions, the longitudinal force required by the vehicle is the driving force demand on the uphill and the braking force demand on the downhill. In order to meet the same longitudinal force target, the output driving force of the motor or the engine braking effect can be improved by adjusting the transmission ratio, or the speed and stability can be adjusted by controlling the brake force (hydraulic brake or regenerative brake). Therefore, the transmission ratio and the brake force are essentially different control means for the longitudinal force, and there is a mutual coupling and coordination relationship between them.

[0003] The above disclosed technical solutions at least have the following technical problems:

[0004] However, under complex hill road conditions, the adjustment of transmission ratio and brake force has two sides:

[0005] When the gear position is selected too low (high transmission ratio), the motor torque can be amplified to provide strong motor braking effect on the downhill, enhancing safety. However, at the same time, the motor operates in the high speed range, increasing energy consumption, noise and mechanical wear, and possibly leading to excessive battery discharge rate, reducing the range.

[0006] When the gear position is selected too high (low transmission ratio), the motor speed is reduced, the system efficiency is improved, and the operation is more stable, which helps to improve energy consumption performance and comfort. However, under hill road conditions, the driving force is insufficient at this time, and the motor braking effect is weakened on the downhill, which may lead to excessive dependence on hydraulic braking.

[0007] When the hydraulic brake force is too high, the vehicle can quickly reduce the speed during downhill or deceleration to ensure driving safety. However, for electric vehicles, excessive dependence on hydraulic braking may lead to brake disc heat decay, posing a safety hazard.

[0008] When the hydraulic braking force is low, although it is beneficial to reduce the hydraulic braking load, prolong the service life of the braking system, and improve the energy recovery rate, in the case of long downhill or emergency deceleration, the vehicle may be underbraked, unable to ensure driving safety, and excessively dependent on regenerative braking, i.e. energy recovery, which may be limited in the case of full battery or high temperature, and unable to fully meet the demand.

[0009] And in the case of high motor speed, i.e. low gear, it is easier to provide strong regenerative braking force; in the case of high gear (low transmission ratio): low motor speed, relatively weak regenerative braking force.

[0010] On a long downhill road, the duration of energy recovery braking force should be prioritized to move further before the battery is full;

[0011] On a short downhill road, the efficiency, energy consumption and comfort of energy recovery are prioritized.

[0012] As can be seen, in the downhill road conditions of an electric vehicle, the transmission ratio and the braking force are key control variables that affect the realization of longitudinal force. Both have high and low trade-off problems, and need to be coordinated to balance power performance, safety and energy consumption. However, most existing shift control methods still match the motor speed and vehicle speed as the main basis, and only in some scenarios the braking system is called passively, lacking a joint optimization control mechanism from the essence of longitudinal force. This leads to the current electric vehicle in complex slope, the shift strategy is difficult to fully coordinate the role of transmission ratio and braking force, and cannot realize efficient energy utilization and driving safety at the same time.

[0013] To solve the above problems, the present application provides a solution. SUMMARY

[0014] In order to overcome the above-mentioned defects of the prior art, the embodiments of the present application provide a shift control method, device, equipment and medium for adaptive slope road conditions, which solves the problem of brake control that balances energy efficiency, safety and comfort of vehicles in different slope road conditions through cooperative optimization of shift control based on transmission ratio and hydraulic braking force.

[0015] To achieve the above-mentioned purpose, the present application provides the following technical solutions:

[0016] The application discloses a shift control method for adaptive hill road conditions, comprising the following steps: acquiring slope data and vehicle data, analyzing required wheel end torque, and inversely deriving a first transmission ratio with the available torque curve of a power source and a target working speed as constraints; based on the pre-acquired vehicle required longitudinal force, eliminating the engine braking force bound by the transmission ratio acquired according to the first transmission ratio analysis, and combining the brake system regeneration constraint and the speed constraint to obtain a first hydraulic braking force; based on Monte Carlo random sampling, sampling the first transmission ratio and the first hydraulic braking force, and randomly grouping a transmission ratio and a hydraulic braking force to form a shift control group to obtain a plurality of shift control groups; based on the pre-acquired relationship between the shift control group and the required longitudinal force, screening a plurality of candidate shift control groups to obtain a plurality of enumerated shift control groups satisfying the required longitudinal force; simulating the application of the plurality of enumerated shift control groups in shift control respectively, and evaluating the simulation effect, constructing a relationship coordinate system of the shift control group and the evaluation result, selecting a suitable shift control in combination with the slope type, mapping the rotation ratio in the shift control to the corresponding gear position, and applying the shift control.

[0017] In a preferred embodiment, the acquiring slope data and vehicle data and analyzing required wheel end torque specifically comprises: the vehicle data comprises a constant speed cruise state, disc temperature and driver input; the slope data comprises a target vehicle direction and a first slope angle of a horizontal plane; a multi-source expected acceleration is set according to the vehicle data and the slope data, and the multi-source expected acceleration comprises a first expected acceleration, a second expected acceleration and a third expected acceleration; the multi-source expected acceleration is combined and truncated to an allowed interval to obtain a fourth expected acceleration; a required longitudinal force is analyzed according to the fourth expected acceleration and the slope; and a torque of the required longitudinal force acting on a wheel side is obtained as the required wheel end torque.

[0018] In a preferred embodiment, the inversely deriving a first transmission ratio with the available torque curve of a power source and a target working speed as constraints specifically comprises: the available torque curve is quantified according to the maximum torque that the power source can provide at a certain speed for torque constraint; an expected power source speed selected based on a working point is taken as the target working speed for target speed constraint; an approximate model of power source torque amplification or reduction to the wheel end is constructed; a second transmission ratio satisfying the torque constraint is inversely derived according to the approximate model; a third transmission ratio satisfying the torque constraint is inversely derived according to the approximate model; and the larger one of the first transmission ratio and the second transmission ratio is taken as the first transmission ratio.

[0019] In a preferred embodiment, the engine braking force bound by the transmission ratio obtained according to the first transmission ratio analysis is specifically: obtaining a negative torque curve, matching the corresponding negative torque according to the power source speed; and mapping the negative torque to the wheel end through an approximate model to deduce the engine braking force bound by the transmission ratio; the initial hydraulic braking force is distributed and determined by combining the regenerative constraint and the rate constraint of the braking system, specifically: obtaining the regenerative capacity of the inverter and the upper limit of the charging power that the battery can accept, and providing a torque form expression, taking the minimum value of the two as the maximum available regenerative torque upper limit, and converting it into a first regenerative braking force through an approximate model; based on the slope data and vehicle data, the recoverable energy of the slope section and the remaining energy receiving capacity of the battery are calculated, the two are compared to determine the type of slope and generate the regenerative constraint corresponding to the type of slope; the second regenerative braking force is obtained by analyzing the regenerative constraint and the maximum available regenerative torque upper limit; the rate constraint is a preset torque change limit per period; the second regenerative braking force is truncated to the braking force interval of the rate constraint to obtain a third regenerative braking force; the first hydraulic braking force is obtained by subtracting the engine braking force bound by the transmission ratio and the third regenerative braking force from the required longitudinal force.

[0020] In a preferred embodiment, the comparison of the two determines the type of slope and generates the regenerative constraint corresponding to the type of slope, specifically: the regenerative constraint includes long-slope regenerative constraint and short-slope regenerative constraint; when the total recoverable energy of the slope section is greater than the remaining energy receiving capacity of the battery, it is a long-slope regenerative constraint, otherwise it is a short-slope regenerative constraint; when the long-slope regenerative constraint, the second regenerative braking force takes the equivalent value of the first regenerative braking force; when the short-slope regenerative constraint, the second regenerative braking force is obtained as the regenerative braking force corresponding to the highest recovery efficiency in the pre-obtained regenerative efficiency curve.

[0021] In a preferred embodiment, the several enumerated shift control groups that meet the required longitudinal force are obtained by screening the several candidate shift control groups according to the relationship between the pre-obtained shift control groups and the required longitudinal force, specifically: obtaining the shift control groups and the corresponding actual longitudinal force from the pre-obtained database; screening the database shift control groups with the same actual longitudinal force as the required longitudinal force, and matching them with several candidate shift control groups; screening the matched several candidate shift control groups as enumerated shift control groups.

[0022] In a preferred embodiment, the relationship coordinate system of the shift control group and the evaluation result is specifically: the evaluation result is a weighted value of multi-dimensional features; the shift control group and the weighted value of each group of multi-dimensional features are respectively mapped into a three-dimensional rectangular coordinate system and fitted into a curved surface to obtain the relationship coordinate system; a preset limit range is obtained; a peak value in the relationship coordinate system is taken as a candidate curved surface not exceeding the limit range; the slope type includes a long slope and a short slope; when the regenerative constraint is a long slope regenerative constraint, the slope type is a long slope, and at this time, an enumerated shift control group with the smallest hydraulic braking force in the candidate curved surface is selected as a suitable shift control; when the regenerative constraint is a short slope regenerative constraint, the slope type is a short slope, and at this time, an enumerated shift control group corresponding to the peak value of the weighted value of the multi-dimensional features of the candidate curved surface is selected as a suitable shift control.

[0023] A shift control device for adaptive hill road conditions comprises a transmission ratio initialization module, a hydraulic braking force initialization module, a shift control group derivation module, a demand longitudinal force matching module, and a shift control determination module. The transmission ratio initialization module is configured to obtain slope data and vehicle data, analyze demand wheel end torque, and inversely deduce a first transmission ratio by taking the available torque curve of a power source and the target working speed as constraints. The hydraulic braking force initialization module is configured to eliminate the engine braking force bound by the transmission ratio obtained by analyzing the first transmission ratio based on the pre-obtained vehicle demand longitudinal force, and combine the regenerative constraint and the speed constraint of the braking system to obtain a first hydraulic braking force. The shift control group derivation module is configured to sample the first transmission ratio and the first hydraulic braking force based on Monte Carlo random sampling, and randomly group a transmission ratio and a hydraulic braking force to obtain a shift control group, thereby obtaining a plurality of shift control groups. The demand longitudinal force matching module is configured to filter a plurality of candidate shift control groups according to the relationship between the pre-obtained shift control group and the demand longitudinal force, thereby obtaining a plurality of enumerated shift control groups that meet the demand longitudinal force. The shift control determination module is configured to apply the plurality of enumerated shift control groups to shift control respectively, evaluate the simulation effect, construct a relationship coordinate system of the shift control group and the evaluation result, select a suitable shift control according to the slope type, and map the transmission ratio in the shift control to the corresponding gear position for application to the shift control.

[0024] An electronic device comprises at least one processor and a memory connected to the at least one processor in communication. The memory stores a computer program executable by the at least one processor. The computer program is executed by the at least one processor to enable the at least one processor to perform the adaptive hill road condition shift control method.

[0025] A computer readable storage medium stores a computer program, which is executed by a processor to implement an adaptive hill road condition shift control method.

[0026] The technical effects and advantages of the adaptive gear shifting control method, device, equipment and medium for slope road conditions of the present application are as follows:

[0027] 1. The present application obtains slope data and vehicle state information, analyzes vehicle demand wheel end torque, and reverses the first transmission ratio with the available torque curve and target working speed of the power source as constraints; on this basis, the engine braking force bound by the transmission ratio is eliminated, and the regenerative constraint and speed constraint of the braking system are combined to distribute the first hydraulic braking force; then the transmission ratio and hydraulic braking force are combined to generate a plurality of gear shifting control groups by using Monte Carlo random sampling, and the enumerated gear shifting control groups that meet the longitudinal force demand are obtained by screening the gear shifting control group and the demand longitudinal force relationship obtained in advance; finally, the enumerated control groups are simulated and applied to gear shifting control, the relationship coordinate system of the gear shifting control group and the evaluation result is constructed, the optimal control scheme is selected combined with the slope type, and the rotation ratio in the control is mapped to the actual gear position, realizing adaptive gear shifting control of the electric vehicle in complex slope road conditions. The present application is particularly suitable for long downhill working conditions, and through the optimal selection of rotation ratio and hydraulic braking force, the brake disc load and temperature rise are maximally optimized, the risk of overheating of hydraulic braking is reduced, the power performance, safety and energy efficiency are considered, the energy recovery efficiency is improved, and the smoothness and comfort of vehicle operation are improved. BRIEF DESCRIPTION OF DRAWINGS

[0028] Figure 1 The figure is a flowchart of the adaptive gear shifting control method for slope road conditions of the present application;

[0029] Figure 2 The figure is a structural diagram of the adaptive gear shifting control device for slope road conditions of the present application. DETAILED DESCRIPTION

[0030] The technical solutions in the embodiments of the present application will be described clearly and completely below with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor fall within the scope of protection of the present application.

[0031] Embodiment 1, Figure 1 The adaptive gear shifting control method for slope road conditions of the present application is given, including the following steps:

[0032] S1, obtain slope data and vehicle data, analyze demand wheel end torque, and reverse the first transmission ratio with the available torque curve and target working speed of the power source as constraints.

[0033] In the embodiment, the slope data and vehicle data are acquired, and the required wheel end torque is analyzed, specifically:

[0034] The vehicle data includes a constant speed cruise state, a disc temperature, and a driver input;

[0035] The slope data includes a target vehicle direction and a first slope angle of a horizontal plane.

[0036] A multi-source desired acceleration is set according to the vehicle data and the slope data, and the multi-source desired acceleration includes a first desired acceleration, a second desired acceleration, and a third desired acceleration;

[0037] The multi-source desired acceleration is combined, and is truncated to an allowed interval to obtain a fourth desired acceleration;

[0038] A required longitudinal force is analyzed according to the fourth desired acceleration and the slope;

[0039] A torque of the required longitudinal force acting on a wheel side is obtained to obtain the required wheel end torque.

[0040] Further, the specific acquisition method of the multi-source desired acceleration is as follows:

[0041] If the target vehicle is in a constant speed cruise state, a preset short-term tracking error term is acquired as the first desired acceleration;

[0042] The second desired acceleration is mapped according to a depth of a gas pedal depression and an acceleration step rate;

[0043] If the first slope angle is negative, and the disc temperature is greater than a preset first threshold value, the third desired acceleration is set.

[0044] It should be noted that the following is a specific formula of the fourth desired acceleration:

[0045] In the formula, is a combined multi-source desired acceleration, is a minimum acceleration of the allowed interval, is a maximum acceleration of the allowed interval, is truncated to the allowed interval.

[0046] It should be noted that the required longitudinal force is analyzed according to the fourth desired acceleration and the slope, specifically:

[0047] A slope component in a longitudinal direction, a desired power source output, a rolling resistance, and an air resistance are combined to obtain a required longitudinal force, and the slope component in the longitudinal direction is obtained by gravity and the first slope angle. The following is a specific calculation formula of the slope component in the longitudinal direction: In the formula, is a rolling resistance coefficient, is the first desired acceleration.

[0048] It should be noted that the desired power output is expected to be a direct application of Newton's second law in the longitudinal direction, that is, the desired power output is equal to the product of the mass of the vehicle and the fourth desired acceleration.

[0049] It should be noted that the torque of the demand longitudinal force acting on the wheel side is obtained by the specific formula of the demand wheel end torque: , wherein is the demand longitudinal force, is the demand wheel end torque, is the wheel radius.

[0050] It should be noted that the first desired acceleration is mainly used to reflect the longitudinal control demand of the vehicle in the constant speed cruise working condition. When the vehicle is in the constant speed cruise mode, the system calculates the required acceleration or deceleration according to the short-term deviation (i.e. short-term tracking error term) between the target vehicle speed and the actual vehicle speed, so as to realize the speed keeping as smoothly as possible. The purpose of this method is to provide a stable and clear expected acceleration index when the vehicle needs to maintain a constant speed, so that the initial transmission ratio can take into account the cruise stability and energy economy. In terms of acquisition method, mature constant speed cruise control strategy or model predictive control method can be used, and there are many researches and applications in the field, which will not be described here.

[0051] It should be noted that the second desired acceleration is mainly used to depict the driver's active operation (such as the accelerator pedal input) on the vehicle acceleration. Specifically, a corresponding desired acceleration value can be mapped according to the driver's accelerator opening degree and acceleration step rate (i.e. accelerator change rate) to reflect the driver's immediate demand for power response. The purpose of this method is to fully consider the driver's intention when initializing the transmission ratio, so that the transmission ratio can quickly respond to the driving operation and improve the drivability and comfort of the vehicle. The mapping relationship can be established by experimental calibration, empirical model or neural network, which belongs to the existing mature technology, and this application will not be described in detail.

[0052] It should be noted that the third desired acceleration is mainly used for speed control in the downhill and brake system heat safety working conditions. When the slope angle is negative (the vehicle is downhill) and the disc temperature is higher than the preset threshold, the traditional hydraulic brake may cause safety decline due to heat attenuation, so an additional deceleration target is needed to constrain the vehicle speed. The deceleration target is the third desired acceleration, which is used to share part of the braking demand through transmission ratio adjustment or regenerative braking distribution to reduce the heat load of the brake. The purpose is to ensure the safety of the vehicle operation and the reliability of the brake system in the long downhill or high-frequency braking scene. The specific calculation method can be based on the existing brake thermal management model or empirical threshold setting, which belongs to the range of mature control strategies, and will not be described here.

[0053] In the embodiment, the first transmission ratio is obtained by backstepping with the available torque curve of the power source and the target working rotational speed as constraints, specifically:

[0054] The available torque curve is quantified according to the maximum torque that the power source can provide at a certain rotational speed, and the torque constraint is performed;

[0055] The target rotational speed constraint is performed based on the expected power source rotational speed selected by the working point selection as the target working rotational speed;

[0056] An approximate model of torque amplification or reduction of the power source to the wheel end is constructed;

[0057] The second transmission ratio that meets the torque constraint is backstepped according to the approximate model;

[0058] The third transmission ratio that meets the torque constraint is backstepped according to the approximate model;

[0059] The larger of the first transmission ratio and the second transmission ratio is taken as the first transmission ratio.

[0060] It should be noted that the following is a feasible approximate model of torque amplification or reduction of the power source to the wheel end: , wherein is the output torque, is the transmission ratio, is the differential total ratio, is the transmission efficiency; wherein the resistance and error terms are omitted, and only used for initialization, which ensures that the initial value is in a relatively reliable value, so in application it will be approximately equal to the equal sign.

[0061] It should be noted that the following is a feasible derivation formula of the minimum transmission ratio that meets the torque constraint:

[0062] , wherein, is the expression form of the available torque curve, that is, the maximum torque that the power source can provide at the power source rotational speed , is the wheel end torque;

[0063] The minimum transmission ratio (second transmission ratio) derived is: .

[0064] It should be noted that when is negative (braking force), the available torque curve is replaced by the pre-obtained negative torque curve .

[0065] It should be noted that the following is a feasible specific formula of the third transmission ratio: , wherein, is a target power source speed, is a wheel angular velocity;

[0066] It should be noted that the following is a specific formula of the first transmission ratio: .

[0067] It should be noted that the power source includes but is not limited to a motor and an engine.

[0068] It should be noted that the rolling resistance is mainly derived from the energy loss of the tire in the ground deformation process, and its size is closely related to the vehicle weight, tire characteristics and road conditions. In the slope working condition, the rolling resistance is an important part of the longitudinal resistance, which has an influence on vehicle acceleration, deceleration and stability. When calculating the rolling resistance, a coefficient is usually used, that is, the approximate result is obtained by multiplying the normal load of the vehicle and the rolling resistance coefficient. The rolling resistance coefficient can be calibrated according to factors such as tire model, road roughness and tire pressure. The purpose of introducing the rolling resistance in this embodiment is to fully reflect the constraint of the vehicle operating environment on the power demand when calculating the required longitudinal force and further backstepping the required wheel end torque, so as to ensure that the transmission ratio initialization is more in line with the actual road conditions. The calculation method of rolling resistance has a large number of mature research and engineering application, and this application will not be repeated.

[0069] It should be noted that the air resistance is the resistance generated by the relative motion of the vehicle with the air during driving, and its size is proportional to the windward area of the vehicle, the air resistance coefficient and the square of the vehicle speed. In the medium and high speed or downhill sliding working condition, the air resistance often becomes one of the key factors determining the longitudinal power demand of the vehicle. For example, when driving downhill at high speed, the air resistance can reduce the burden of the braking system to a certain extent, but when driving uphill at low speed, its effect can be ignored. The purpose of introducing the air resistance in this embodiment is to more accurately correct the required longitudinal force after combining the multi-source expected acceleration, so that the transmission ratio backstepping result can take into account the dynamics characteristics in different speed intervals. The modeling and calculation method of air resistance has been relatively mature in the field of vehicle dynamics control, and this application will not be repeated.

[0070] In summary, by comprehensively analyzing the slope information, the vehicle state and the multi-source expected acceleration, the required wheel end torque is backstepped, and then combined with the available torque curve of the power source and the target speed constraint, a reasonable first transmission ratio is obtained. The benefits of this design are: on the one hand, it can fully consider the vehicle operating environment (slope, resistance), driver's intention and braking system safety constraints, so that the initial transmission ratio is closer to the actual working condition, and the safety and economy are guaranteed; on the other hand, the accurate initial value selection helps to improve the convergence speed and stability of the subsequent control strategy, reduces the iterative calculation burden, and thus improves the real-time performance and reliability of the overall shift control.

[0071] S2, based on the pre-acquired vehicle demand longitudinal force, eliminating the transmission ratio bound engine braking force obtained according to the first transmission ratio analysis, and combining the brake system regenerative constraint and the rate constraint, a first hydraulic braking force is distributed.

[0072] In the embodiment, the transmission ratio bound engine braking force obtained according to the first transmission ratio analysis is specifically:

[0073] A negative torque curve is obtained, and a corresponding negative torque is matched according to the power source speed;

[0074] And the negative torque is mapped to the wheel end through an approximate model, and the transmission ratio bound engine braking force is inversely deduced.

[0075] It should be noted that the principle of inversely deducing the transmission ratio bound engine braking force by mapping the negative torque to the wheel end through the approximate model is the same as the principle of applying the demand longitudinal force to the wheel edge torque in the foregoing to obtain the demand wheel end torque, which can be reasoned inversely.

[0076] In the embodiment, the initial hydraulic braking force is distributed and determined by combining the brake system regenerative constraint and the rate constraint, and specifically:

[0077] The regenerative capacity of the inverter and the upper limit of the charge power acceptable by the battery are obtained, and a torque form expression is provided, the minimum value of the two is taken as the maximum available regenerative torque upper limit, and the first regenerative braking force is converted through an approximate model;

[0078] Based on the slope data and the vehicle data, the slope energy recoverable amount and the battery remaining energy receiving capacity are calculated, the two are compared to judge the slope type, and the regenerative constraint corresponding to the slope type is generated;

[0079] According to the regenerative constraint and the maximum available regenerative torque upper limit, a second regenerative braking force is obtained by analysis;

[0080] The rate constraint is a preset torque change amplitude limit per period;

[0081] The second regenerative braking force is truncated into the braking force interval of the rate constraint to obtain a third regenerative braking force;

[0082] The demand longitudinal force is subtracted from the transmission ratio bound engine braking force and the third regenerative braking force to obtain a first hydraulic braking force.

[0083] It should be noted that the torque change amplitude limit per period refers to the upper limit torque and the lower limit torque of the torque within a preset time period.

[0084] It should be noted that the demand longitudinal force includes a sum of the transmission ratio bound engine braking force, the hydraulic braking force, and the controllable regenerative braking force.

[0085] It should be noted that the principle of converting the first regenerative braking force into the required wheel end torque by the approximate model is the same as the torque acting on the wheel edge in the foregoing, and the reverse reasoning can be obtained.

[0086] Further, the comparison of the two judges the slope type and generates the regenerative constraint corresponding to the slope type, specifically:

[0087] The regenerative constraint includes long slope regenerative constraint and short slope regenerative constraint;

[0088] When the total recoverable energy of the slope section is greater than the remaining energy capacity of the battery, it is a long slope regenerative constraint, otherwise it is a short slope regenerative constraint;

[0089] When the long slope regenerative constraint, the second regenerative braking force is equal to the first regenerative braking force;

[0090] When the short slope regenerative constraint, the highest recovery efficiency in the pre-acquired regenerative efficiency curve is obtained as the second regenerative braking force.

[0091] It should be noted that the total recoverable energy of the slope section The gravitational potential energy of the car to be driven on the slope difference can be expressed as follows: , wherein is the slope difference; It should be noted that the recoverable energy of the slope section is expressed by gravitational potential energy, which is not accurate, ignoring friction and other resistances, but the purpose of this part is to obtain a more feasible value, which is to make the subsequent steps easier to converge and obtain an efficient initial value.

[0092] It should be noted that the following is a feasible calculation formula for the remaining energy capacity of the battery: , wherein, is the maximum state of charge of the battery, is the remaining state of charge of the current battery, is the total energy capacity of the battery.

[0093] It should be noted that the following is a feasible specific calculation formula for the third regenerative braking force:

[0094] , wherein, is the third regenerative braking force, is the current regenerative braking force, and are the lower limit torque and the upper limit torque of the torque change limit respectively.

[0095] The method can ensure rationality and safety of brake force distribution under different working conditions by eliminating engine braking force bound by transmission ratio and distributing hydraulic braking force under multiple restrictions of regenerative braking capacity, battery receiving capacity and speed constraints. The design has the following advantages: on the one hand, it can avoid the risk of brake disc overheating caused by simply relying on hydraulic braking, and fully utilize the energy recovery system to improve energy utilization efficiency; on the other hand, through slope type identification and speed limiting, the stability of regenerative braking force distribution is ensured, and the problem of overcharging or excessive instantaneous fluctuation of the battery is avoided, thereby improving the stability and reliability of the overall control. In addition, reasonable initial hydraulic braking force selection helps subsequent optimization process to converge faster, reduces iterative calculation burden and improves real-time performance.

[0096] S3, based on Monte Carlo random sampling, sampling the first transmission ratio and the first hydraulic braking force, and randomly combining a transmission ratio and a hydraulic braking force to form a shift control group, to obtain a plurality of shift control groups;

[0097] In this embodiment, the first transmission ratio and the first hydraulic braking force are sampled based on Monte Carlo random sampling, specifically:

[0098] According to the requirements of vehicle dynamics and braking performance, the derived range of the first transmission ratio and the first hydraulic braking force is preset respectively;

[0099] Based on the Monte Carlo random sampling method, a plurality of transmission ratio samples and hydraulic braking force samples are independently generated within the derived range;

[0100] The generated transmission ratio samples and hydraulic braking force samples are combined in a random pairing manner to form a plurality of candidate shift control groups, each of which contains a transmission ratio and a hydraulic braking force.

[0101] It should be noted that Monte Carlo random sampling of the first transmission ratio and the first hydraulic braking force and random combination can generate a wide range of candidate shift control groups in a short time, thereby ensuring the diversity and comprehensiveness of the search space. The advantages of this are: on the one hand, it avoids the problem of local optimum or slow convergence caused by a single initial value, and increases the possibility of finding a global optimal solution; on the other hand, random sampling can quickly generate a large number of reasonably distributed samples under the premise of controllable calculation, providing a sufficient candidate solution set for subsequent multi-dimensional evaluation and optimization, thereby improving the robustness and convergence efficiency of the system shift control strategy.

[0102] S4, according to the relationship between the shift control group and the required longitudinal force obtained in advance, the plurality of candidate shift control groups are screened to obtain a plurality of enumerated shift control groups that meet the required longitudinal force.

[0103] In the embodiment, a plurality of candidate shift control groups are screened according to the pre-acquired relationship between the shift control group and the required longitudinal force, and a plurality of enumerated shift control groups satisfying the required longitudinal force are obtained, specifically as follows:

[0104] The shift control group and the corresponding actual longitudinal force are acquired from the pre-acquired database;

[0105] The database shift control group with the same actual longitudinal force as the required longitudinal force is screened out from the database, and is matched with a plurality of candidate shift control groups;

[0106] The matched plurality of candidate shift control groups are screened out as the enumerated shift control groups.

[0107] It should be noted that the candidate shift control groups are screened by using the existing corresponding relationship between the shift control group and the actual longitudinal force in the database, which can effectively eliminate invalid combinations that do not satisfy the required longitudinal force, and only keep feasible solutions as the enumerated shift control groups. The advantages of this are as follows: on the one hand, the existing data is used for rapid matching, reducing complex calculation and improving screening efficiency; on the other hand, the consistency between the shift control group and the required longitudinal force is strictly constrained, which ensures that the subsequent optimization is performed in a more compact and more reliable solution space, thereby improving the overall calculation efficiency and convergence speed, and also reducing the risk of entering a local invalid solution.

[0108] S5, the plurality of enumerated shift control groups are respectively applied to the shift control, and the simulation effect is evaluated, a relationship coordinate system of the shift control group and the evaluation result is constructed, a suitable shift control is selected in combination with the slope type, and the rotation ratio in the shift control is mapped to the corresponding gear position and applied to the shift control.

[0109] In the present application, the relationship coordinate system of the shift control group and the evaluation result is constructed, specifically as follows:

[0110] The evaluation effect is a weighted value of a plurality of dimensional features;

[0111] The shift control group and the weighted value of each group of the plurality of dimensional features are respectively mapped to a three-dimensional rectangular coordinate system, and are fitted into a surface to obtain the relationship coordinate system;

[0112] A preset limit range is acquired;

[0113] The peak value in the relationship coordinate system is taken to a candidate surface not exceeding the limit range;

[0114] The slope type includes a long slope and a short slope;

[0115] When the regenerative constraint is a long slope regenerative constraint, the slope type is a long slope, and at this time, the enumerated shift control group with the minimum hydraulic braking force in the candidate surface is selected as the suitable shift control;

[0116] When the regenerative constraint is a short slope regenerative constraint, then the slope type is a short slope, at this time the enumeration shift control group corresponding to the peak value of the weighted value of the multi-dimensional feature of the candidate surface is selected as the appropriate shift control.

[0117] It should be noted that the three dimensions of the three-dimensional rectangular coordinate system are rotation ratio, hydraulic braking force and weighted value of multi-dimensional feature.

[0118] It should be noted that when the multi-dimensional evaluation is performed on each shift control group, the braking system thermal risk, regenerative braking persistence, driving comfort and other dimensions can be combined for comprehensive scoring. The evaluation index and calculation method can be set according to actual application requirements, and is not limited to a single evaluation standard. Moreover, it is not the focus of the present application, and is therefore not limited.

[0119] It should be noted that by mapping the results of the enumeration shift control group after multi-dimensional evaluation to the three-dimensional relationship coordinate system, and selecting the appropriate shift control according to the slope type, the differentiation optimization for different driving environments can be achieved. The advantages of this are: on the one hand, by using surface fitting and limit range constraint, the evaluation result is not only a single point selection, but also an optimal solution under the global trend, ensuring the robustness and robustness of the control strategy; on the other hand, by combining the different characteristics of long and short slopes, the safety margin of hydraulic braking force and the comprehensive weighted benefit are respectively focused on, avoiding the problem of "one-size-fits-all" strategy mismatch, thereby improving the adaptive ability and actual use effect of the system in multiple scenarios.

[0120] Example 2, Figure 2The application discloses a shift control device for adaptive hill road conditions, comprising a transmission ratio initialization module, a hydraulic braking force initialization module, a shift control group derivation module, a demand longitudinal force matching module and a shift control determination module. The transmission ratio initialization module is used to obtain slope data and vehicle data, analyze demand wheel end torque, and inversely deduce a first transmission ratio by taking the available torque curve of a power source and a target working speed as constraints. The hydraulic braking force initialization module is used to eliminate engine braking force bound by the transmission ratio obtained by analyzing the first transmission ratio based on the pre-obtained vehicle demand longitudinal force, and combine braking system regeneration constraints and speed constraints to obtain a first hydraulic braking force. The shift control group derivation module is used to sample the first transmission ratio and the first hydraulic braking force based on Monte Carlo random sampling, randomly combine a transmission ratio and a hydraulic braking force to form a shift control group, and obtain a plurality of shift control groups. The demand longitudinal force matching module is used to screen a plurality of candidate shift control groups according to the relationship between the pre-obtained shift control groups and the demand longitudinal force, and obtain a plurality of enumerated shift control groups satisfying the demand longitudinal force. The shift control determination module is used to simulate the plurality of enumerated shift control groups in shift control respectively, evaluate the simulation effect, construct a relationship coordinate system of the shift control group and the evaluation result, select a suitable shift control in combination with the slope type, map the transmission ratio in the shift control to the corresponding gear position, and apply the shift control to the shift control.

[0121] The application further includes an electronic device, comprising at least one processor, and a memory connected with the at least one processor in communication; wherein the memory stores a computer program executable by the at least one processor, and the computer program is executed by the at least one processor to enable the at least one processor to execute the adaptive hill road condition shift control method.

[0122] The application further includes a computer readable storage medium storing a computer program, and the computer program is executed by a processor to implement the adaptive hill road condition shift control method.

Claims

1. A gear shifting control method for adaptive slope road conditions, characterized in that, Includes the following steps: Acquire slope data and vehicle data, analyze the required wheel-end torque, and use the available torque curve of the power source and the target operating speed as constraints to back-calculate the first transmission ratio; Based on the pre-obtained longitudinal force of the vehicle demand, the engine braking force bound to the transmission ratio obtained from the analysis of the first transmission ratio is eliminated, and the first hydraulic braking force is allocated by combining the regenerative constraints and rate constraints of the braking system. Based on Monte Carlo random sampling, the first gear ratio and the first hydraulic braking force are sampled, and a gear ratio and a hydraulic braking force are randomly combined into a shift control group to obtain several shift control groups. Based on the pre-obtained relationship between the shift control group and the required longitudinal force, several candidate shift control groups are screened to obtain several enumerated shift control groups that meet the required longitudinal force. Several enumerated shift control groups are simulated and applied to shift control, and the simulation effect is evaluated. A coordinate system relating shift control groups to evaluation results is constructed. An appropriate shift control is selected based on the slope type, and the rotation ratio in the shift control is mapped to the corresponding gear and applied to shift control.

2. The adaptive slope road condition shifting control method according to claim 1, characterized in that, The acquisition of slope data and vehicle data, and the analysis of required wheel-end torque, specifically involves: Vehicle data includes cruise control status, steering wheel temperature, and driver input; The slope data includes the target vehicle's direction and the first slope angle on the horizontal plane; Based on vehicle data and slope data analysis, a multi-source expected acceleration is set, which includes a first expected acceleration, a second expected acceleration, and a third expected acceleration. By merging the multi-source expected accelerations and truncating them to the allowable range, a fourth expected acceleration is obtained. Based on the fourth expected acceleration and slope analysis, the required longitudinal force is needed; The required wheel end torque is obtained by applying the required longitudinal force to the wheel edge.

3. The adaptive slope road condition shifting control method according to claim 2, characterized in that, The first transmission ratio is obtained by reverse calculation, constrained by the available torque curve of the power source and the target operating speed, specifically as follows: Based on the maximum torque that the power source can provide at a certain speed, the available torque curve is quantified and torque constraints are applied. The target operating speed is constrained by taking the desired power source speed selected based on the operating point; Construct an approximate model of the power source torque amplified or reduced to the wheel end; The minimum transmission ratio that satisfies the torque constraint is calculated based on the approximate modulus and taken as the second transmission ratio. The third transmission ratio that satisfies the torque constraint is derived from the approximate modulus; The larger of the first transmission ratio and the second transmission ratio is taken as the first transmission ratio.

4. The adaptive slope road condition shifting control method according to claim 3, characterized in that, The engine braking force bound to the transmission ratio obtained from the analysis of the first transmission ratio is specifically as follows: Obtain the negative torque curve and match the corresponding negative torque according to the power source speed; And by using an approximate model, the negative torque is mapped to the wheel end, and the engine braking force tied to the transmission ratio is derived in reverse. The initial hydraulic braking force is allocated and determined by combining the regenerative constraints and rate constraints of the braking system, specifically as follows: The upper limits of the inverter's regenerative capacity and the battery's acceptable charging power are obtained and expressed in the form of torque. The minimum of the two is taken as the upper limit of the maximum available regenerative torque and converted into the first regenerative braking force through an approximate model. Based on ramp data and vehicle data, the recoverable energy of the ramp section and the remaining battery capacity are calculated. The two are compared to determine the ramp type and generate the regeneration constraints corresponding to the ramp type. The second regenerative braking force is obtained by analyzing the regenerative constraints and the upper limit of the maximum available regenerative torque. The rate constraint is a preset limit on the torque variation per cycle. The second regenerative braking force is cut off within the braking force range constrained by the rate to obtain the third regenerative braking force; Subtracting the engine braking force and the third regenerative braking force bound to the transmission ratio from the required longitudinal force yields the first hydraulic braking force.

5. The adaptive slope road condition shifting control method according to claim 4, characterized in that, The comparison of the two to determine the ramp type and generate the corresponding regeneration constraints is as follows: The regeneration constraints include long slope regeneration constraints and short slope regeneration constraints; When the total recoverable energy of the slope section is greater than the remaining energy capacity of the battery, it is a long slope regeneration constraint; otherwise, it is a short slope regeneration constraint. When long slope regeneration is constrained, the second regeneration braking force is taken as the same value as the first regeneration braking force; When short-slope regeneration is constrained, the regeneration braking force corresponding to the highest recovery efficiency in the pre-acquired regeneration efficiency curve is obtained as the second regeneration braking force.

6. The adaptive slope road condition shifting control method according to claim 5, characterized in that, The process involves filtering several candidate shift control groups based on the pre-obtained relationship between the shift control groups and the required longitudinal force, resulting in several enumerated shift control groups that satisfy the required longitudinal force. Specifically: The shift control group and the corresponding actual longitudinal force are obtained from the pre-acquired database; Filter out the database shift control groups whose actual longitudinal force is the same as the required longitudinal force, and match them with several candidate shift control groups; Several matching candidate shift control groups are selected as enumerated shift control groups.

7. The adaptive slope road condition shifting control method according to claim 6, characterized in that, The coordinate system for constructing the relationship between the shift control group and the evaluation results is specifically as follows: The evaluation result is a weighted value of multidimensional features; The shift control group and the weighted values ​​of each group of multi-dimensional features are mapped to a three-dimensional rectangular coordinate system and fitted into a surface to obtain the relational coordinate system. Obtain the preset limit range; In the relational coordinate system, the peak value is selected downwards, and the candidate surface is taken within the limit range. The slope types include long slopes and short slopes; When the regeneration constraint is a long slope regeneration constraint, the slope type is a long slope. In this case, the enumerated shift control group with the smallest hydraulic braking force among the candidate surfaces is selected as the appropriate shift control. When the regeneration constraint is a short slope regeneration constraint, the slope type is short slope. In this case, the enumerated shift control group corresponding to the peak value of the weighted value of the multidimensional features of the candidate surface is selected as the appropriate shift control.

8. An apparatus for using the adaptive slope road condition shift control method as described in any one of claims 1-7, characterized in that, It includes a transmission ratio initialization module, a hydraulic braking force initialization module, a shift control group derivative module, a demand longitudinal force matching module, and a shift control determination module; The transmission ratio initialization module is used to acquire slope data and vehicle data, analyze the required wheel-end torque, and back-calculate the first transmission ratio using the available torque curve of the power source and the target operating speed as constraints. The hydraulic braking force initialization module is used to eliminate the engine braking force bound to the transmission ratio obtained according to the analysis of the first transmission ratio based on the pre-acquired longitudinal force of the vehicle demand, and to allocate the first hydraulic braking force by combining the regenerative constraints and rate constraints of the braking system. The shift control group derivative module is used to sample the first transmission ratio and the first hydraulic braking force based on Monte Carlo random sampling, and randomly form a shift control group with a transmission ratio and a hydraulic braking force to obtain several shift control groups. The longitudinal force matching module is used to filter several candidate shift control groups based on the pre-acquired relationship between the shift control group and the longitudinal force demand, and obtain several enumerated shift control groups that meet the longitudinal force demand. The shift control determination module is used to simulate and apply several enumerated shift control groups to shift control, evaluate the simulation effect, construct a coordinate system relating shift control groups to evaluation results, select appropriate shift control based on slope type, and map the rotation ratio in shift control to the corresponding gear and apply it to shift control.

9. An electronic device, characterized in that, The electronic device includes: At least one processor; and, A memory communicatively connected to the at least one processor; wherein, The memory stores a computer program that can be executed by the at least one processor, the computer program being executed by the at least one processor to enable the at least one processor to perform the adaptive slope road condition shift control method as described in any one of claims 1 to 7.

10. A computer-readable storage medium storing a computer program, characterized in that, When the computer program is executed by the processor, it implements the adaptive slope road condition shifting control method as described in any one of claims 1 to 7.

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