Simulation-based driver gear shifting control method

Abstract

The invention belongs to the technical field of vehicle simulation application, and particularly relates to a driver gear shifting control method based on simulation. The method comprises the following steps: determining a driving task and collecting vehicle driving information; according to the driving task and the vehicle driving information, the gear position is judged through a gear shifting control strategy; introducing a first principle of a gear shifting control strategy, namely a speed and acceleration principle; introducing a second principle of a gear shifting control strategy: introducing a traction surplus percentage to distinguish different driver types and taking the traction surplus percentage as a preset parameter of a gear shifting controller; a third principle of the gear shifting control strategy is introduced, wherein the third principle is a swing gear shifting eliminating principle; the position of a clutch pedal is output, it is ensured that the clutch is connected, and the gear shifting process is completed. The problems that a traditional driver controller only depends on the rotating speed of an engine for gear shifting, so that the traction force requirement of automobile running cannot be met under some conditions, and the driver controller cannot reflect the gear shifting habits of different drivers are solved.

Description

Technical Field

[0001] This invention belongs to the technical field of vehicle simulation applications, and more specifically, relates to a simulation-based driver gear shifting control method. Background Technology

[0002] The driver controller is a virtual driver that drives a vehicle model in a simulation environment, allowing for testing of software functions used in the vehicle within a SiL (Software in the Loop) environment. The driver controller corresponds to a real driver in the vehicle, meaning it should be able to autonomously determine the correct response in different situations. Different shift types can be defined based on driving conditions and transmission design. Generally, upshifts and downshifts are distinguished based on the relationship between the current gear and the target gear. Based on the direction of torque transmission, there are pull-type and push-type shifts. Pull-type shifts refer to the driving process where the engine outputs positive torque. Conversely, push-type shifts refer to the driving process where the engine outputs negative torque.

[0003] Chinese patent document CN105351512A discloses a clutch control method for downshifting in an automatic transmission system, comprising: (1) acquiring vehicle signals; (2) determining whether the vehicle needs to shift up or down based on the acquired vehicle signals; (3) if the vehicle needs to shift up or down, determining whether to shift up or down based on a shift control strategy; (4) determining the working condition where the vehicle needs to shift up or down based on the shift control strategy, and performing clutch disengagement control; (5) performing shift control based on the clutch disengagement control; and (6) after confirming successful shifting, performing clutch engagement control.

[0004] In existing transmission development, a driver controller for manual transmission vehicles is used. This controller simulates the starting process in detail, but shifting gears depends solely on engine speed, ignoring all other factors, such as resistances to overcome, including required acceleration, road gradient, air resistance, and rolling resistance. That is, once the engine exceeds a certain speed during acceleration or falls below another speed limit during braking, the next gear is engaged. This strategy can easily result in gears that do not meet traction requirements. Furthermore, this strategy does not differentiate speed limits based on driver type or vehicle, engine, and powertrain configuration. To more realistically reflect the driving process, all these factors must be considered. Summary of the Invention

[0005] The present invention aims to overcome at least one of the defects of the prior art and provide a novel shifting strategy method based on the percentage of traction surplus during vehicle operation, so as to solve the problem that the traditional driver controller only relies on engine speed for shifting, which leads to the inability to meet the traction requirements of the vehicle in some situations, and the driver controller cannot reflect the shifting habits of different drivers.

[0006] The detailed technical solution of this invention is as follows: A simulation-based driver gear shift control method, the method comprising: S1. Define the driving task and collect vehicle driving information; The vehicle driving information includes: driving task, environment, and vehicle status; the driving task includes target speed and target acceleration values, the environment includes road slope, air resistance, etc., and the vehicle status includes required data such as engine torque, engine speed, tire radius, gear ratio of the transmission, gear ratio of the differential, current gear, current pedal position, and vehicle weight.

[0007] S2. Determine the gear position based on the driving task and vehicle driving information through the gear shift control strategy; S3. Perform a gear shift: Simulate the clutch pedal position to ensure the clutch is engaged and complete the gear shift process.

[0008] Furthermore, S2 specifically includes: The first principle of introducing a shift control strategy is the speed and acceleration principle: only gears that simultaneously meet the speed and acceleration requirements can be selected. The speed standard is as follows: based on the given target speed v and engine speed... Tire radius and the gear ratio of the differential Determine the corresponding gear ratio of the transmission: (1); The minimum and maximum engine speed of a gasoline engine ranges from 800 rpm to 6300 rpm. Due to the different gear ratios of the transmission, each gear can cover a different speed range. By using formula (1), it can be calculated which gear(s) currently meet the driving speed requirements.

[0009] The acceleration standard is as follows: compare the traction supply value and the traction demand value. At the current engine speed, when the traction supply value of the engaged gear is greater than or equal to the traction demand value, the gear meets the driving needs of the vehicle. The traction requirement of a vehicle is determined by the driving resistance, which includes four parts: rolling resistance, air resistance, gradient resistance, and acceleration resistance. Total driving resistance, i.e. traction force requirement Including all the above-mentioned driving resistances, the calculation formula is: (2); Rolling resistance , The rolling resistance coefficient, Where is the slope angle, m is the vehicle mass, and g is the acceleration due to gravity; air resistance A is the maximum cross-sectional area. air density, is the dimensionless air drag coefficient, and v is the vehicle speed; Slope resistance , The slope angle; Acceleration resistance , To accelerate the vehicle, For the engine's rotational inertia, Let be the moment of inertia of the wheel. This refers to the gear ratio of the gearbox. This refers to the gear ratio of the differential. The radius of the tire; Using the above formula, the total driving resistance is defined as: (3); Total driving resistance is the traction force required for a car to move.

[0010] The vehicle's traction supply is as follows: based on the engine's full-load characteristic curve, at each engine speed... Allocate a maximum available engine torque The force acting on the wheels is calculated based on the gear ratio of the transmission and the rear axle differential, and is defined as the traction force supply. : (4); In formula (4), It is the engine's maximum usable torque, which, in the engine's full-load characteristic curve, is determined by the engine speed. Therefore, the available traction force depends solely on the engine speed and gear ratio.

[0011] Based on acceleration criteria, it can be determined whether the traction supply related to the gear is sufficient to meet the required traction at the current engine speed. Therefore, traction surplus is defined as: (5); When the traction surplus is positive, the current gear can meet the acceleration requirements during driving.

[0012] Furthermore, a second principle of the shift control strategy is introduced: the percentage of traction surplus is used to differentiate between different driver types and is used as a pre-given parameter for the shift controller, specifically including: (1) Calculate the percentage of traction surplus for the current gear; The traction surplus percentage is calculated by dividing the traction surplus value of the current gear by the maximum traction surplus value achievable under the same boundary conditions: (6).

[0013] (2) Set the percentage of surplus based on the type of driver; Drivers can be divided into two types: The driver has a sporty driving style and chooses this gear to provide the maximum potential traction. The driver has an energy-saving driving style and chooses this gear to save energy. In the simulation environment, the traction surplus percentage used to determine the driver type will be used as a set value input. In order to distinguish this set value from the actual traction surplus percentage reached during the simulation, the driver's surplus percentage, i.e. the set percentage, is used as a characteristic parameter of the driver type. The set percentage remains constant during a single driving process of the same driver. 0% and 100% traction surplus values ​​represent two extreme cases, and sporty or fuel-efficient drivers typically drive at a lower or higher percentage value between the two, respectively.

[0014] (3) Gear selection: Select the highest gear when the traction surplus percentage is greater than or equal to the set percentage; For vehicles equipped with manual transmissions, the set percentage is typically between the traction surplus percentages of two adjacent gears. Therefore, there are two possible shifting options: 1. Select the gear closest to the desired traction surplus percentage, i.e., possibility 1; 2. Select a gear greater than or equal to the desired traction surplus percentage, i.e., possibility 2.

[0015] Furthermore, a third principle for shift control strategy is introduced: the principle of eliminating swaying shifts, including introducing a traction surplus percentage tolerance or adopting a predictive multi-shift strategy. Option 1: Introduce a traction surplus percentage tolerance; As mentioned earlier, since the set percentage is an absolute value, fluctuations in the traction surplus percentage at the critical point of the set value can cause wobbling shifting. Therefore, a traction surplus percentage tolerance is introduced: a range is provided to replace the constant set percentage, and shifting will only be triggered when the preset tolerance range is exceeded.

[0016] Option 2: Adopt a proactive multi-shift strategy; A look-ahead time is set, and the shifting process within the look-ahead time is calculated in advance. If multiple shifts occur within the look-ahead time, the controller skips the gears with engagement times shorter than the look-ahead time, thereby suppressing unnecessary shifting operations.

[0017] Furthermore, S3 specifically includes: The gear shifting process consists of six stages: the first stage is the transition or preparation stage before shifting; the second stage is disengaging the clutch; the third stage is shifting gears in the gearbox after disengaging the clutch; the fourth stage is engaging the clutch until the engagement point after engaging the corresponding gear; the fifth stage is eliminating clutch slippage and balancing speed differences; and the sixth stage is when the clutch is fully engaged and the gear shift is successful.

[0018] Furthermore, the fifth stage for eliminating clutch slippage balance speed difference also includes: optimizing the position and holding time of the clutch pedal at the engagement point; The speed difference between the engine and transmission input shaft is eliminated. During this stage, the clutch pedal is slowly released and paused at the engagement point, allowing the engine to be adjusted to the target speed via frictional torque, after which the clutch can fully engage. Therefore, the position of the clutch pedal at the engagement point and the duration of its hold are key parameters for balancing the speed difference, and can be determined through analysis of measurement data. The clutch characteristic curve describes the relationship between clutch travel and torque; furthermore, the corresponding clutch pedal position can be determined based on the clutch travel. To determine the clutch travel, the clutch torque is calculated. That's all: (7); In formula (7), For the engine's rotational inertia, To represent the downshift or upshift gradient, it can be further written as , Depends on shift point And whether the shift type is upshift or downshift, single shift or continuous shift, The duration of the speed difference balancing process; When a higher gear is engaged, i.e., during the upshift simulation operation of the driver's controller, the clutch engagement time, i.e., the duration of the speed difference balancing process, is crucial. Taking an average value of 0.2s, the clutch torque can be obtained by substituting into formula (7). Calculated; When a lower gear is engaged, i.e., during the downshift simulation operation of the driver controller, since the output torque of the transmission (equivalent to the perceptible acceleration of the vehicle's shift shock) is basically constant, the duration of the speed difference balancing process between different gears is constrained by formula (8). ; (8); It is the output torque of the transmission. This refers to the gear ratio of the transmission gear. Keep it within an acceptable range, that is This is set as a constant, thus creating different durations. The clutch torque can be obtained by substituting into formula (7). Calculated.

[0019] Compared with the prior art, the beneficial effects of the present invention are as follows: (1) The present invention provides a simulation-based driver shift control method, which enables the driver controller to comprehensively consider more factors, including driving tasks, vehicle performance or different driver driving styles, and select the appropriate gear.

[0020] (2) The present invention provides a simulation-based driver shift control method, which simulates the real-time position of the clutch pedal in the driver controller based on data analysis of the clutch pedal position during the actual driving process of the driver, and more realistically depicts the driver's operation during the shift process. Attached Figure Description

[0021] Figure 1 This is a flowchart of a simulation-based driver gear shifting control method provided by the present invention. Figure 2 This is a traction diagram of a five-speed manual transmission vehicle in Embodiment 1 of the present invention; Figure 3 This is a schematic diagram of two possible gear shifts and their traction surplus percentage when the percentage is set to 20% in Embodiment 1 of the present invention. Figure 4 This is a simulation of an urban loop road section in Embodiment 1 of the present invention without eliminating swaying gear shifting; Figure 5 This is a schematic diagram of the gear shifting process optimized by adjusting the traction surplus percentage tolerance in Embodiment 1 of the present invention; Figure 6 This is a schematic diagram of the predictive multi-shift strategy in Embodiment 1 of the present invention; Figure 7 This is a schematic diagram of the clutch pedal travel during gear shifting in Embodiment 1 of the present invention; Figure 8 This is an analysis of measured data from the energy-saving driver in Embodiment 1 of the present invention; Figure 9 This is a simulation result data analysis of the driver controller setting percentage of 25% and tolerance of 20% in Embodiment 1 of the present invention; Figure 10 This is an analysis of measured data from a sporty driver in Embodiment 1 of the present invention; Figure 11 This is a simulation result data analysis of the driver controller setting percentage of 75% and tolerance of 20% in Embodiment 1 of the present invention; Figure 12 This is a simulation result data analysis of the driver controller setting percentage of 80% and tolerance of 15% in Embodiment 1 of the present invention; Figure 13 This is a comparison chart of the simulation results and the actual measurement results of a sport driver in Embodiment 1 of the present invention. Detailed Implementation

[0022] The present invention will be further described below with reference to the accompanying drawings and embodiments.

[0023] It should be noted that the following detailed descriptions are exemplary and intended to provide further illustration of the invention. Unless otherwise specified, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains.

[0024] It should be noted that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the scope of exemplary embodiments according to the invention. As used herein, the singular form is intended to include the plural form as well, unless the context clearly indicates otherwise. Furthermore, it should be understood that when the terms "comprising" and / or "including" are used in this specification, they indicate the presence of features, steps, operations, devices, components, and / or combinations thereof.

[0025] Where there is no conflict, the embodiments and features in the embodiments of the present invention can be combined with each other.

[0026] Example 1 The new shift controller has two main tasks: to determine the new shift strategy, i.e., under what circumstances to engage which gear, and to realistically depict the shift process.

[0027] The requirements for the shift controller are that it can truly describe the starting process and the shifting process. In addition, it should be able to well follow the given driving speed. At the same time, it should be able to reflect the shifting strategies of different types of drivers to conform to the diverse performances in actual driving. Existing controllers can well simulate the starting process, but the shifting function is only initially implemented: if the engine speed is greater than a certain value, upshift; if it is lower than another speed limit, downshift. Therefore, the engine speed is the only influencing factor determining the shift. The shifting strategy of the present invention is that the driver controller can comprehensively consider more factors including driving tasks, vehicle performance or different driving styles of drivers, and can select an appropriate gear. In addition, the position of the clutch pedal during the shifting process should also be presented in detail.

[0028] For Figure 1 , this embodiment provides a simulation-based driver shift control method, and the method includes: S1. Define the driving task and collect vehicle driving information; The vehicle driving information includes: driving task, environment and vehicle state; the driving task includes a speed target value and an acceleration target value, the environment includes road surface gradient, air resistance, etc., and the vehicle state includes required data such as engine torque, engine speed, tire radius, gear ratio of the transmission, gear ratio of the differential, current gear, current pedal position, vehicle mass, etc.

[0029] S2. According to the driving task and the vehicle driving information, judge the gear position through a shift control strategy; Specifically, to select an appropriate gear, first introduce two limit criteria according to the tractive effort diagram: speed criterion and acceleration criterion; In the tractive effort diagram, as Figure 2 shown, the traction supply and the traction demand are closely related to the driving speed in different gears. It can be clearly seen from Figure 2 that the change process of the traction provided by each gear is consistent with the change process of the engine full-load characteristic curve: the curve initially rises to a certain extent, then remains basically constant, and finally decreases. Due to different gear ratios, different speed and acceleration ranges can be covered. This means that certain ranges, such as extremely low or relatively high driving speeds or when there is a high traction demand, can only be driven in specific gears.

[0030] Figure 2 also shows situations with multiple choices. For example, in the figure, gears 2, 3, 4 and 5 can reach 45 km / h under a slope of 0% ( (Here, all resistance is converted into gradient). In this situation, the shifting strategy should be determined by the driver or controller. A sporty driver is one who prefers speed-oriented driving habits, while an economy-oriented driver is one who prefers fuel-efficient driving habits. Sporty drivers prefer second gear to gain higher potential acceleration or climbing ability, while economy-oriented drivers choose fifth gear. To differentiate and quantify these driver types and choices, the concept of traction surplus is introduced. This leads to the first principle of the shift control strategy: The first principle is the speed and acceleration principle: only gears that simultaneously meet the speed and acceleration requirements can be selected.

[0031] The speed standard is as follows: based on the given target speed v and engine speed... Tire radius and the gear ratio of the differential This allows us to determine the corresponding gear ratio of the transmission.

[0032] (1); According to the traction force diagram, Figure 2 It can also be seen that the minimum and maximum engine speed of the gasoline engine is between 800 rpm and 6300 rpm. Due to the different gear ratios of the gearbox, the speed range that each gear can cover is different. Through formula (1), it can be calculated which one or more gears meet the driving speed requirements.

[0033] The acceleration standard is as follows: compare the traction supply value and the traction demand value. At the current engine speed, when the traction supply value of the engaged gear is greater than or equal to the traction demand value, the gear can meet the driving needs of the vehicle. The traction requirement of a vehicle is determined by the driving resistance, which consists of four parts: rolling resistance, air resistance, gradient resistance, and acceleration resistance.

[0034] Rolling resistance Rolling resistance is the force generated in the opposite direction of the wheel's movement as it rolls. This is mainly due to the deformation of the tire under the influence of the vehicle's weight. Rolling resistance is directly proportional to the wheel load, and the calculation formula is: (9); dimensionless coefficient This is called the rolling resistance coefficient, which depends on the driving speed, wheel load, and tire characteristics. On a smooth, dry road surface, The reference value is 0.01.

[0035] When driving on a slope, due to the slope angle The wheel load acting on the wheel becomes a normal component, and the rolling resistance is ultimately described by the formula: (10).

[0036] air resistance Air resistance is a key component of driving resistance, especially at high speeds. Specifically, it includes pressure drag caused by the air displaced by the moving vehicle, drag caused by eddies generated by the pressure difference, friction between the air and the vehicle's surface, and airflow resistance. Air resistance is the square of the relative velocity between the vehicle and the air along the vehicle's longitudinal axis; typically, it is assumed that the wind speed is zero, in which case the relative velocity equals the driving speed. In addition, air resistance is the maximum cross-sectional area A (measured in a plane perpendicular to the direction of motion) and air density. and dimensionless air drag coefficient The function is typically used to calculate air density at an air pressure of 1.1013 bar, a relative humidity of 60%, and a temperature of 20°C. In summary, the formula for air resistance is: (11).

[0037] Slope resistance The sliding force equal to the vehicle's mass m is calculated using the following formula: , The slope angle; If road slope is expressed as a percentage, it's important to note that the angle of inclination and the slope value are not directly proportional. Slope is the ratio of the length of an opposite side to the length of an adjacent side in a right triangle; therefore, a 45° angle equals tan(45°), which equals 1, or 100%. A 10% slope means: ,Right now

[0038] Acceleration resistance This only occurs when the vehicle accelerates or decelerates, and according to Newton's second law, a force is required. To make a vehicle of mass m accelerate Acceleration or braking. Furthermore, the moment of inertia of all rotating parts of the vehicle, such as the engine, transmission, starting components, and wheels, must also be considered; A simplified representation of the rotational inertia of the engine, clutch, central management system (ZMS), and transmission can be summarized as the engine's rotational inertia. Therefore, acceleration resistance Depends on the differential gear ratio Gear position and tire radius The calculation formula is: (12); Total driving resistance, i.e. traction force requirement Including all the above-mentioned driving resistances, the calculation formula is: (2) Rolling resistance , The rolling resistance coefficient, Where is the slope angle, m is the vehicle mass, and g is the acceleration due to gravity; air resistance A is the maximum cross-sectional area. air density, is the dimensionless air drag coefficient, and v is the vehicle speed; Slope resistance , The slope angle; Acceleration resistance , To accelerate the vehicle, This is the engine's moment of inertia. Let be the moment of inertia of the wheel. This refers to the gear ratio of the gearbox. This refers to the gear ratio of the differential. This is the tire radius.

[0039] Using the above formula, the total driving resistance is defined as: (3) Total driving resistance is the traction force required for a vehicle to move. Traction force requirement is the sum of all driving resistances and the force required to accelerate the rotational inertia of the wheels and engine. Since the moment of inertia of the clutch and dual-mass flywheel can be incorporated into the engine's rotational inertia, the rotational inertia of the mass of the gearbox and the components between the gearbox and the wheels can be ignored. Therefore, traction force requirement is affected by speed, gear ratio, and acceleration.

[0040] The vehicle's traction supply is as follows: based on the engine's full-load characteristic curve, at each engine speed... Allocate a maximum available engine torque The force acting on the wheels is calculated based on the gear ratio of the transmission and the rear axle differential, and is defined as the traction supply. : (4) In formula (4), It is the engine's maximum usable torque, which, in the engine's full-load characteristic curve, is determined by the engine speed. Therefore, the available traction force depends solely on the engine speed and gear ratio.

[0041] Based on acceleration criteria, it can be determined whether the traction supply related to the gear is sufficient to meet the required traction at the current engine speed. Therefore, traction surplus is defined as: (5) When the traction surplus is positive, the current gear can meet the acceleration requirements during driving.

[0042] Figure 2 As can be seen from the diagram, if the target driving speed is 45 km / h, gears 1-5 can all meet the speed requirement according to the traction diagram. However, due to the different gear ratios of different gears, the traction provided by each gear is also different. The lower the gear, the greater the traction supply, that is, the greater the traction surplus. (See the diagram.) This indicates that the car is currently on a slope of 0%. When driving on a road section where all resistance is converted into gradient, gear 2 has surplus traction. At this time, other gears can also meet the acceleration requirements during driving, but the surplus traction value will decrease as the gear increases.

[0043] In special circumstances, there may not be a gear that simultaneously meets both speed and acceleration standards. In such cases, the lowest gear that meets the speed standard is engaged, thereby minimizing the difference between the target speed and the actual speed.

[0044] Preferably, the second principle of the shift control strategy is to introduce a traction surplus percentage to differentiate between different driver types and use it as a pre-given parameter for the shift controller, specifically including: (1) Calculate the percentage of traction surplus for the current gear; The traction surplus percentage is calculated by dividing the traction surplus value of the current gear by the maximum traction surplus value achievable under the same boundary conditions. The maximum traction surplus is usually achieved in the lowest drivable gear. (6) (2) Set the percentage of surplus based on the type of driver; The formula above shows that when the traction surplus percentage is 100%, the selected gear is the lowest gear that meets the speed requirements. Drivers with a sporty driving style choose this gear to provide the maximum potential traction. Conversely, at the other extreme, the traction surplus is 0%, meaning the selected gear provides exactly the traction required. Traction is used entirely to complete the driving task, and shifting to a higher gear is not possible. Therefore, this type of driver is categorized as having an energy-efficient driving style. 0% and 100% traction surplus values ​​represent two extremes; typically, sporty or energy-efficient drivers will drive at a lower or higher percentage, respectively.

[0045] In the simulation environment, the traction surplus percentage used to determine the driver type is input as a setpoint. To distinguish this setpoint from the actual traction surplus percentage achieved during the simulation, a driver surplus percentage is set; this paper uses the term "setpoint percentage" as a characteristic parameter of the driver type. The setpoint percentage remains constant throughout a single driving cycle for the same driver. Figure 3 As shown, Figure 3 The diagram shows different gear selection options (possibility 1 and possibility 2) when driving a certain distance, given the driving task, i.e., the speed and acceleration, as well as the corresponding traction surplus percentage diagrams in 4th and 5th gear.

[0046] (3) Gear selection: Select the highest gear when the traction surplus percentage is greater than or equal to the set percentage; For vehicles equipped with manual transmissions, the set percentage is typically between the traction surplus percentages of two adjacent gears. Therefore, there are two possible shift points, see... Figure 3 1. Choose the gear that is closest to the expected traction surplus percentage (possibility 1); 2. Choose the gear that can at least reach (greater than or equal to) the expected traction surplus percentage (possibility 2).

[0047] Refer to the driving process from 20s to 25s in the figure. Figure 3In a driving task with a set percentage of 20%, at 20 seconds, the instantaneous traction surplus percentage in 4th gear is 22.5%, and in 5th gear it is 7.5%. In this case, 4th gear is both the closest to 20% and meets the requirement of being greater than 20%. When accelerating further to approximately 21 seconds, the instantaneous traction surplus percentage in 4th gear is 36%, and in 5th gear it is 7%. At this point, although the traction surplus percentage in 4th gear is still greater than the set percentage, the traction surplus percentage in 5th gear is numerically closer to the driver type defined by 20%. However, if the 4th-5th gear upshift is performed in the first manner at this point, it will lead to unnecessary frequent shifting afterward, as adjacent gears may approach the set values ​​from both positive and negative sides.

[0048] Therefore, this invention adopts the second approach in the gear shift control module, namely, selecting the highest gear where the traction surplus percentage is greater than or equal to a set percentage. Figure 3 In the middle, because the traction surplus percentage of 5th gear could not reach 20%, the controller drove in 4th gear.

[0049] Preferably, the third principle of the shift control strategy is to eliminate swaying during shifting; See Figure 4 This paper demonstrates a simulation of an urban loop road section based on a traction surplus percentage shifting strategy. The urban loop is a speed curve in an urban area based on measured data. Because the percentage set in driving requirements is defined as an absolute value, in some situations, when the traction surplus percentage of a certain gear is exactly at a critical value, a phenomenon may occur where the gear is engaged and immediately disengaged, or frequent gear shifts occur within a short period. This behavior is called swaying shifting and may lead to significant deviations in vehicle speed, such as… Figure 4 As shown. To avoid wobbling during gear shifting, this invention introduces two solutions: Option 1: Introduce a traction surplus percentage tolerance; As mentioned earlier, since the set percentage is an absolute value, fluctuations in the traction surplus percentage at the critical point of the set value can cause wobbly shifting. The purpose of introducing a traction surplus percentage tolerance is to provide a range instead of a constant set percentage. For example, when the vehicle is traveling in third gear, if the set percentage is 50% and the tolerance is 30%, then a shift will only occur if third gear cannot meet the 20%-80% traction surplus range. In this case, even if fourth gear can achieve a 50% traction surplus, the current gear will not disengage. This principle also applies to downshifting. This mechanism is equivalent to a hysteresis effect, meaning that a shift is only triggered after the preset tolerance range is exceeded.

[0050] like Figure 5As shown, under the known driving task (speed and acceleration), the chart compares the gear shifting behavior of a real driver and driver controllers with and without a 15% tolerance setting during the same road segment. The top chart displays the driving task; to facilitate observation, the acceleration values ​​are multiplied by 10. The second chart shows the gear shifting process of a real driver during the actual driving of this route. The third chart shows the simulated gear shifting process of a driver controller with a set percentage of 80% but no tolerance range. The fourth chart shows the simulated gear shifting process of a driver controller with a 15% traction surplus percentage tolerance added to the 80% set percentage. It can be seen that the driver controller with a 15% tolerance not only reduces shifting wobbles compared to the no-tolerance solution but also more closely resembles the shifting behavior of a real driver.

[0051] Option 2: Adopt a predictive multi-shift strategy.

[0052] By setting a look-ahead time, the controller performs forward calculations for gear shifts within that timeframe, essentially predicting the shift process. If multiple shifts occur within the look-ahead time, the controller skips gears with engagement times shorter than the look-ahead time, thus suppressing unnecessary shifting operations. In actual driving, the driver observes the surrounding environment, gathers traffic and road gradient information, and performs corresponding actions based on the specific situation. This means that the driver always makes predictive judgments before taking vehicle control actions.

[0053] By introducing a predictive mechanism into the driver controller, unnecessary gear shifts in the next time period can be avoided based on the current gear shift trend. Since simulations are based on sampled data and calculated sequentially over time, it's impossible to predict the state of the next sampling point during the simulation. A feasible solution is to generate a forward-shifted speed curve offline and input it into the controller along with the original data. Using this "predictive" speed data, the driver controller obtains the gear shift curve using the same calculation algorithm. This curve is geometrically identical to the actual driving gears, differing only in its forward shift on the time axis. By anticipating future gear requirements, the controller can advance or delay shifting opportunities, thus skipping gears that only require brief engagement. The core idea is to suppress unnecessary shifting operations through a predictive mechanism when the driver controller triggers multiple gear shifts in a short period.

[0054] Predictive multi-shift strategy execution, such as Figure 6The diagram illustrates several different multi-shift scenarios. The blue curve represents the original shift process based on the traction surplus percentage output, while the red curve represents the gear change curve calculated based on the speed curve shifted forward in time. If the target (original) shift gear does not match the predicted value at the same moment, or if multiple shift requests occur within the predicted time, the current gear will remain engaged until the target gear value equals the predicted value, at which point the shift operation will be performed.

[0055] However, it is difficult to establish a uniform advance time limit rule applicable to all situations. If the advance time is too short, the effect of suppressing frequent gear shifts may not be fully realized; if the advance time is too long, necessary gear shifting operations may be mistakenly ignored.

[0056] Therefore, given the established tolerance, this invention employs a 1-second anticipation time. This setting also effectively addresses the following situation: when the low gear is at the end of the engine's full-load characteristic curve, its traction supply curve drops sharply, providing less traction. The anticipation mechanism avoids the resulting brief downshifting.

[0057] S3. Perform gear shift: Simulate the clutch pedal position to ensure the clutch is engaged and complete the gear shift process; To fit the clutch pedal travel curve as realistically as possible, such as Figure 7 As shown by the red curve, the entire gear shifting process is abstracted into six parts. The first stage is the transition or preparation stage before shifting. The second stage is disengaging the clutch. The third stage is shifting gears in the transmission after disengaging the clutch. The fourth stage is engaging the clutch until the engagement point after engaging the corresponding gear. The fifth stage is eliminating clutch slippage and balancing speed differences. The sixth stage is the clutch fully engaging, and the gear shift is successful.

[0058] The modeling for stages two, four, and six is ​​achieved by specifying the slope of the clutch pedal travel, which is correlated with the pedal travel and defined by the duration of time. The duration is determined through statistical analysis of the measurement results.

[0059] The fifth stage of eliminating clutch slippage and balancing speed differences also includes optimizing the clutch pedal position and holding time at the engagement point. During this fifth stage, the speed difference between the engine and the transmission input shaft is eliminated. In this stage, the clutch pedal is slowly released and paused at the engagement point, allowing the engine to be adjusted to the target speed via frictional torque, after which the clutch can fully engage. Therefore, the clutch pedal position and holding time at the engagement point are key parameters for balancing speed differences and can be determined through analysis of measurement data. The clutch characteristic curve describes the relationship between clutch travel and torque; furthermore, the corresponding clutch pedal position can be determined based on the clutch travel.

[0060] To determine the clutch travel, the clutch torque is calculated using the following formula. : (7); For the engine's rotational inertia, This is referred to here as the downshift or upshift gradient, which can be further written as... . Depends on shift point And the shift type, whether it's upshifting or downshifting, single shift or continuous shifting. The duration of the speed difference balancing process. Both variables were further determined through actual measurements.

[0061] During the analysis of the measurement data, it was found that the driver's operation of the clutch differed when upshifting and downshifting.

[0062] Upshift speed difference balance duration and clutch torque: Table 1 Summary of relevant measurement data for upshifting operations

[0063] Table 1 summarizes the relevant measurement data for upshifting operations, recorded in a Mercedes-Benz C-Class sedan equipped with a 1.6L gasoline engine and a 6-speed manual transmission. Six different drivers participated in daily driving tests. Engine speed, duration Δt, and acceleration / deceleration gradient are shown as averages. Negative values ​​in the table indicate engine drag during deceleration.

[0064] In addition to clutch torque, engine drag torque must also be considered during gear shifts. When the accelerator is not pressed, the engine decelerates at a gradual rate of approximately 1000 rpm / s due to internal friction. This effect makes upshifting easier because the drag torque acts in the same direction as the required engine speed change. Conversely, downshifting takes longer because this additional resistance must be overcome. As can be seen from the table, the gear gradient tends to flatten as the gear difference decreases during upshifting. During the 4th-5th gear shift with a gear difference of 1.236, the engine speed may even be too low due to the drag torque, requiring engagement torque to pull it up again, thus creating a positive gradient.

[0065] As shown in Table 1, apart from the average time of 0.37s for shifting from 1st to 2nd gear, the duration of balancing the speed difference during upshifting is almost constant, approximately 0.2s. One possible reason for this deviation is that experienced drivers engage the clutch particularly slowly when shifting from 1st to 2nd gear to suppress the strong jolt. Therefore, this shift process takes longer. Furthermore, shifting from 1st to 2nd gear is a typical stop-and-go shift, where drivers may deliberately release the clutch slowly in traffic jams to gain time and observe the situation. Therefore, in the data analysis, this type of shift is considered an abnormal value and is not included in the results; the remaining values ​​are used to calculate the constant duration of clutch torque.

[0066] Therefore, in the upshift simulation operation of the driver controller, The clutch engagement time, i.e., the duration of the speed difference balancing process, is determined by driving conditions and shifting strategy. Taking an average value of 0.2s, the clutch torque can be obtained by substituting into formula (7).

[0067] Calculation of downshift speed difference balance duration and clutch torque: Table 2 Summary of measurement data and related calculation results for downshifting operations

[0068] As shown in Table 2, the duration of the balance speed difference increases with the increase in gear ratio. This is because drivers adjust the clutch pedal engagement speed to keep the jolt within an acceptable range during actual operation.

[0069] When shifting into a lower gear, i.e., during the driver's controller's downshift simulation, two factors affect the perceived shift shock: First, the gear ratio difference, i.e., the difference between lower gears, is larger, leading to a greater speed difference that needs to be balanced at the clutch; second, lower gears have higher transmission ratios, which increases the torque at the transmission output, thereby enhancing the perceived vehicle acceleration. These two effects are summarized by the following formula: (8); In formula (8), This refers to the transmission's output torque, which is equivalent to the vehicle's perceptible acceleration. This formula clearly shows that the speed difference caused by gear shifts, along with the transmission ratio, affects shift shock. To achieve greater comfort, drivers typically consciously release the clutch gently to... Keep it within an acceptable range, that is Set to a constant value; this results in different durations Δt.

[0070] Substituting formula (7) into formula (8) can be written as: , Represents the clutch torque or transmission input torque, determined by the gear ratio of the engaged gear. and Establish the conversion relationship. Since the output torque of all downshifting transmissions is roughly at the same level, for example, an average torque of 78 Nm corresponds to 0.4 m / s. 2 The vehicle's longitudinal acceleration means that in this case, the clutch torque and travel depend only on the target gear (its gear ratio).

[0071] Therefore, during the downshift simulation of the driver controller, the output torque of the transmission can be... As a fixed value, the speed difference balancing time Δt under different gears can be obtained according to formula (8). Further, the clutch torque and stroke are determined according to formula (7).

[0072] This embodiment, through summarizing and applying simulations and verifications of a large amount of measurement data, clarifies the shifting strategy characteristics corresponding to different types of drivers, verifies and parameterizes the driver controller. Subsequently, the simulation results of the driver controller are compared with the experimental analysis conclusions to verify the controller's functional reliability.

[0073] Since the measurement data already includes the actual driver's gear selection information, the actual traction surplus percentage can be calculated. Further classification and research on the traction surplus percentage and gear distribution can then complete the description of driver characteristics.

[0074] To evaluate the consistency between simulation and measurement data, this embodiment introduces four eigenvalues ​​to compare the real driver and the controller: IO_v_pro: Consistency of driving speed over time, with an error range within 2km / h; IO_G_pro: Consistency of gear selection over time; Diff_F: The sum of the frequency distribution deviations of the traction surplus percentage across ten levels from 10% to 100%; Diff_G: The sum of deviations in the distribution of each gear level.

[0075] For fuel-efficient drivers, the measurement data characterizing their traits were derived from actual driving records. The vehicle used for measurement was a Mercedes-Benz C-Class sedan equipped with a six-speed transmission. The gasoline engine produced 115 kW of power and a maximum torque of 250 Nm.

[0076] It can be determined through measurement data analysis, such as Figure 8As shown, this is a driver who prefers an energy-efficient driving style. Their traction surplus percentage is primarily maintained between 30% and 50%, and they use 6th gear most of the time. Since there are no more economical options, they cannot shift up to achieve a lower traction surplus. They only switch to gears 1-5 when the vehicle speed is below the minimum allowable speed for 6th gear.

[0077] Based on the frequency distribution of the measurement data, the controller's traction surplus percentage is set to 25%, with a tolerance of 20%. For example... Figure 9 As shown, the simulation results are in high agreement with the measured data. The maximum distribution range of traction surplus percentage is concentrated between 40% and 50%, and more than 80% of the running time is in sixth gear. In the time dimension, the consistency between gear selection and the measured data analysis results is as high as 92%. The difference rates between the traction surplus percentage distribution and the gear distribution are 0.5% and 2.3%, respectively.

[0078] For sporty drivers, load spectrum measurement data was used as the actual measurement reference. Load spectrum measurement aims to obtain the maximum load data of the transmission system, providing a basis for component size design. Therefore, this measurement data is particularly suitable for calibrating controller parameters for sporty driving styles. This load spectrum measurement used a Mercedes-Benz C-Class vehicle equipped with a six-speed transmission. The test vehicle was equipped with a four-cylinder gasoline engine (150kW, 310Nm), and data was collected at the Nürburgring racetrack. Given the mountainous terrain of the area, the corresponding gradient data needed to be matched according to the driving trajectory when calculating driving resistance.

[0079] Figure 10 This data is based on actual measurements taken by sporty drivers. Analysis of the measurement data revealed that the traction surplus percentage is concentrated in the range of 50% and above. Therefore, in the initial settings of the driver controller, the set percentage was set to 75% and the tolerance was set to 20%.

[0080] Figure 11 The simulation results are shown: the speed consistency rate (IO_v_pro) and gear consistency rate (IO_G_pro) reach 91% and 77%, respectively. Although the traction surplus percentage distribution deviation rate is only 0.6%, the gear distribution deviation rate reaches 2.7%. Compared with a real driver, the controller spends too much time in 5th gear and too little time in 4th and 3rd gear. If some 5th gear is shifted to 4th gear and some 4th gear is shifted to 3rd gear, the distribution consistency will be improved. This needs to be achieved by increasing the set percentage.

[0081] When the set percentage is increased to 80% and combined with a 15% tolerance, a better gear distribution can be obtained, such as... Figure 12As shown, the consistency of the corresponding evaluation metrics has also been improved (IO_v_pro: 94%, IO_G_pro: 85%, Diff_F: 1.6%, Diff_G: 1.3%).

[0082] See driving process Figure 13 Under the premise of clearly defining the driving task, namely time, speed, and acceleration, the results of comparing the gear position of the driver controller optimized by the present invention with the measured data in the time domain are shown. Qualitative analysis shows that the actual gear position recording curve of the real driver and the gear position recording curve in the simulated driver controller can track the speed curve well, and the gear position change pattern is highly similar.

Claims

1. A simulation-based driver gear shifting control method, characterized in that, The method includes: S1. Define the driving task and collect vehicle driving information; S2. Determine the gear position based on the driving task and vehicle driving information through the gear shift control strategy; S3. Execute the gear shift, simulate the clutch pedal position, ensure the clutch is engaged, and complete the gear shift process successfully.

2. The simulation-based driver gear shifting control method according to claim 1, characterized in that, The shift control strategy includes: speed and acceleration principles; Only gears that simultaneously meet the speed and acceleration requirements can be selected; The speed standard is as follows: based on the given target speed v and engine speed... Tire radius and the gear ratio of the differential Determine the corresponding gear ratio of the transmission: （1）； By setting the engine's minimum and maximum engine speeds, the gear that meets the current driving speed requirements can be calculated. The acceleration standard is as follows: compare the traction supply value and the traction demand value. At the current engine speed, when the traction supply value of the engaged gear is greater than or equal to the traction demand value, the gear meets the driving needs of the vehicle. The traction requirement of a vehicle is determined by the driving resistance, which includes four parts: rolling resistance, air resistance, gradient resistance, and acceleration resistance. Total driving resistance, i.e. traction force requirement Including all the above-mentioned driving resistances, the calculation formula is: （2）； Rolling resistance , The rolling resistance coefficient, The slope angle, m For vehicle quality, g It is the acceleration due to gravity; air resistance A is the maximum cross-sectional area. air density, It is a dimensionless air drag coefficient. v For vehicle speed; Slope resistance , The slope angle; Acceleration resistance , To accelerate the vehicle, This is the engine's moment of inertia. Let be the moment of inertia of the wheel. This refers to the gear ratio of the gearbox. This refers to the gear ratio of the differential. The radius of the tire; Using the above formula, the total driving resistance is defined as: （3）； Total driving resistance is the traction force required for a car to move. The vehicle's traction supply is determined by the engine's full-load characteristic curve at each engine speed. Allocate a maximum available engine torque The force acting on the wheels is calculated based on the gear ratio of the transmission and the rear axle differential, and is defined as the traction force supply. : （4）； In formula (4), It is the engine's maximum usable torque, which, in the engine's full-load characteristic curve, is determined by the engine speed. Therefore, the available traction force depends only on the engine speed and gear ratio; Based on the acceleration criteria, it can be determined whether the traction supply related to the gear is sufficient to meet the required traction at the current engine speed. Therefore, the traction surplus is defined as: （5）； When the traction surplus is positive, the current gear meets the acceleration requirements during driving.

3. A simulation-based driver gear shifting control method according to claim 1 or 2, characterized in that, The shift control strategy also includes: introducing a traction surplus percentage to distinguish different driver types and using it as a pre-given parameter for the shift controller, specifically: (1) Calculate the percentage of traction surplus for the current gear; The traction surplus percentage is calculated by dividing the traction surplus value of the current gear by the maximum traction surplus value achievable under the same boundary conditions: （6）； (2) Set the percentage of surplus based on the type of driver; There are two types of drivers: those with a sporty driving style who choose this gear to provide the maximum potential traction, and those with an energy-saving driving style who choose this gear to save energy. In the simulation environment, the traction surplus percentage used to determine the driver type will be used as a set value input. In order to distinguish this set value from the actual traction surplus percentage reached during the simulation, the driver's surplus percentage, i.e. the set percentage, is used as a characteristic parameter of the driver type. The set percentage remains constant during a single driving process of the same driver. (3) Gear selection: Select the highest gear under the condition that the traction surplus percentage is greater than or equal to the set percentage.

4. The simulation-based driver gear shifting control method according to claim 3, characterized in that, The shift control strategy also includes: introducing the principle of eliminating sway shifting, that is, adopting the traction surplus percentage tolerance strategy; It provides a range instead of a constant percentage setting, and gear shifting will only be triggered when the preset tolerance range is exceeded.

5. The simulation-based driver gear shifting control method according to claim 4, characterized in that, The introduction of the principle to eliminate swaying shifting also includes: adopting a predictive multi-shifting strategy; A look-ahead time is set, and the shifting process within the look-ahead time is calculated in advance. If multiple shifts occur within the look-ahead time, the controller skips the gears whose engagement time is less than the look-ahead time.

6. The driver shifting control method based on simulation according to claim 5, characterized in that, S3 specifically includes: The gear shifting process consists of six stages: the first stage is the transition or preparation stage before shifting; the second stage is disengaging the clutch; the third stage is shifting gears in the gearbox after disengaging the clutch; the fourth stage is engaging the clutch until the engagement point after engaging the corresponding gear; the fifth stage is eliminating clutch slippage and balancing speed differences; and the sixth stage is when the clutch is fully engaged and the gear shift is successful.

7. The simulation-based driver gear shifting control method according to claim 6, characterized in that, The fifth stage for eliminating clutch slippage and balance speed difference also includes: Optimize the clutch pedal position and holding time at the engagement point. The corresponding clutch pedal position can be determined based on the clutch travel. To determine the clutch travel, the clutch torque is calculated. That's all: （7）； In formula (7), For the engine's rotational inertia, To represent the downshift or upshift gradient, further written as , Depends on shift point And whether the shift type is upshift or downshift, single shift or continuous shift, The duration of the speed difference balancing process; When a higher gear is engaged, i.e., during the upshift simulation operation of the driver's controller, the clutch engagement time, i.e., the duration of the speed difference balancing process, is crucial. Taking an average value of 0.2s, the clutch torque can be obtained by substituting into formula (7). Calculated; When a lower gear is engaged, i.e., during the downshift simulation operation of the driver controller, since the output torque of the transmission is basically constant, the duration of the speed difference balancing process between different gears is constrained by formula (8). ; （8）； In formula (8), It is the output torque of the transmission. This refers to the gear ratio of the transmission gear. Keep it within an acceptable range. Assuming a constant value, different durations Δt are formed, and the clutch torque can be calculated by substituting Δt into formula (7).

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