Universe vehicle speed gradient self-adaptive abrupt slope slow descent control method and vehicle

Abstract

The invention relates to an abrupt slope slow descent control method self-adaptive to a global vehicle speed gradient and a vehicle, and belongs to the field of vehicle control. For a vehicle matched with an electric drive system with a fixed transmission ratio, feedforward torque is obtained according to the current vehicle speed of the vehicle and the pre-obtained corresponding relation between the vehicle speed and the motor torque and according to the motor torque, the feedforward torque is superposed to a torque output value of vehicle speed closed-loop control, and the vehicle is controlled to reach the HDC target vehicle speed; the corresponding relation is in positive correlation within the peak torque range of the motor, and the vehicle speed in the corresponding relation is divided into an acceleration interval, an HDC constant torque interval and a deceleration interval along with the increase of the vehicle speed; the HDC constant torque interval corresponds to an HDC target vehicle speed interval; the motor torque corresponding to the HDC constant torque interval is a constant value, and the constant value is obtained through calculation according to the full-load mass, the HDC target vehicle speed and the HDC gradient intermediate value; and the vehicle speed is ensured to be stably reduced or increased to the target vehicle speed along with the increase or decrease of the motor torque.

Description

Technical Field

[0001] The invention relates to a steep slope descent control method and a vehicle with global vehicle speed and gradient self-adaptation, belonging to the field of whole vehicle control. Background Art

[0002] With the upgrading of automobile electronic control and intelligence, people pay more and more attention to the safety and comfort of automobiles. Hill Down Control (HDC) is an automatic control system for vehicles driving downhill. When the vehicle encounters a long downhill steep slope, the steep slope descent function can automatically control the vehicle to stabilize at a low speed and achieve smooth descent when the driver releases the accelerator and brake pedals. Passenger cars mainly identify the slope of the road through slope sensors or high-precision maps. When encountering a long downhill steep slope, they control the hydraulic brake (fuel vehicle) or electric brake (new energy vehicle) to achieve a low speed and smooth descent. However, commercial vehicles are relatively long. For example, tractors can be tens of meters long, and the front and compartment are separated. The slope sensor is generally installed inside the front of the vehicle. Therefore, the slope information obtained by the slope sensor is difficult to cover the entire length of the vehicle body. In addition, the weight of commercial vehicles is large, and the weight variation between empty and full load is large, which can reach more than 60,000 kg, and the maximum variation range can reach 300% of the empty weight. At the same time, the road conditions of commercial vehicles are poor. For example, heavy-loaded dump trucks often work under mine roads. It is difficult to rely on slope sensors or high-precision maps to obtain the accurate slope of the road surface, and it is impossible to provide accurate input for vehicle control. In addition, passenger cars are mostly equipped with automatic multi-speed transmissions. When going down a steep slope, if the vehicle speed cannot be reduced in time, the gears will automatically shift up as the vehicle speed increases. As the vehicle speed continues to increase, the transmission will continue to shift up, forming a vicious cycle, which can lead to HDC loss of control. To avoid this phenomenon, the prior art usually only sets a fixed target speed and target gear. Although this method can avoid HDC loss of control caused by automatic shifting, the target speed of HDC is also limited to a fixed speed and cannot be adjusted according to changes in the driver's intentions.

[0003] The Chinese patent authorization announcement document with announcement number CN114179621B discloses a vehicle steep slope descent control method and device. When the vehicle enters the steep slope descent mode, the method controls the actual vehicle speed to the steep slope descent speed according to the energy recovery torque, thus solving the problem of achieving a smooth descent of the vehicle through hydraulic braking.

[0004] The Chinese patent application publication number CN116985770A discloses a steep slope descent pre-control method and device. When the vehicle driving state information meets the steep slope descent pre-control conditions, the method brakes the vehicle by actively building up pressure, thereby improving the driver's sense of driving safety.

[0005] However, both solutions require the vehicle to detect the slope of the current slope. When the vehicle cannot effectively collect slope information, the HDC function cannot be entered. For commercial vehicles with separate front and body, the slope information obtained by the slope sensor cannot accurately reflect the slope of the entire vehicle. At the same time, the weight of commercial vehicles varies greatly when fully loaded and unloaded, making these two solutions difficult to apply to commercial vehicles. In addition, the target vehicle speed of these two solutions is a fixed value and cannot be adjusted according to the driver's intention, thus failing to achieve full-range vehicle speed control. Summary of the invention

[0006] The purpose of the present invention is to provide a steep slope descent control method and vehicle with full-range vehicle speed and slope adaptiveness, which is aimed at vehicles with an electric drive system with a fixed transmission ratio, and solves the problem that the existing steep slope descent technology is heavily dependent on the acquired slope information and is not suitable for commercial vehicles with large mass changes and with separate front and body types.

[0007] To achieve the above object, the solution of the present invention includes:

[0008] The present invention provides a steep slope descent control method with global vehicle speed and gradient self-adaptation. In the HDC mode, the vehicle obtains a feedforward torque according to the corresponding motor torque based on the current vehicle speed and the pre-acquired correspondence between the vehicle speed and the motor torque, and superimposes the feedforward torque on the torque output value of the closed-loop speed control to control the vehicle to the HDC target speed.

[0009] The vehicle speed and motor torque in the corresponding relationship are positively correlated within the motor peak torque range, and the vehicle speed in the corresponding relationship is divided into an acceleration interval, an HDC constant torque interval and a deceleration interval as the vehicle speed increases; the HDC constant torque interval corresponds to the HDC target vehicle speed interval; the motor torque corresponding to the HDC constant torque interval is a constant value, which is calculated based on the full load mass, the HDC target vehicle speed, and the HDC slope middle value; the HDC slope middle value is the slope value between the maximum slope and the minimum slope within the slope range adapted to the HDC mode.

[0010] Furthermore, in the corresponding relationship, the motor torque corresponding to the acceleration interval decreases linearly from the constant value of the motor torque corresponding to the HDC constant torque interval to 0 as the vehicle speed decreases; the motor torque corresponding to the deceleration interval increases linearly from the constant value of the motor torque corresponding to the HDC constant torque interval to the motor peak torque as the vehicle speed increases.

[0011] Furthermore, there are at least two corresponding relationships, the corresponding corresponding relationship is selected according to the HDC target vehicle speed, the HDC target vehicle speed is determined according to the vehicle speed when the vehicle enters the HDC mode, and the HDC target speed range in the corresponding relationship corresponding to the HDC target vehicle speed is determined according to the HDC target vehicle speed and a pre-set vehicle speed error range; the corresponding relationship corresponding to the large HDC target vehicle speed has the following characteristics compared to the corresponding relationship corresponding to the small HDC target vehicle speed: in the acceleration interval and the deceleration interval, the motor torque corresponding to the same vehicle speed is smaller.

[0012] The HDC target speed is determined according to the vehicle speed when the vehicle enters the HDC mode, and the corresponding relationship between the vehicle speed and the motor torque changes with the change of the HDC target speed, which can achieve full-range linear speed control and fully meet the driver's driving intention.

[0013] Furthermore, the HDC slope median value is the slope of the slope with the highest probability of appearing in the working condition.

[0014] Furthermore, the corresponding motor torque is multiplied by the mass coefficient to be used as the feedforward torque; the mass coefficient is determined according to the ratio of the current actual mass of the vehicle to the full-load mass.

[0015] Furthermore, the parameters of the vehicle speed closed-loop controller in the vehicle speed closed-loop control are parameters that make the absolute value of the torque output value of the vehicle speed closed-loop control less than or equal to the absolute value of the feedforward torque.

[0016] Furthermore, after the feedforward torque is superimposed on the torque output value of the vehicle speed closed-loop control to obtain the HDC total torque for driving the motor response, the opening of the accelerator pedal and the brake pedal is also determined; if the brake pedal opening is greater than 0, it is also determined whether the braking torque for the vehicle braking system response obtained according to the brake pedal is less than or equal to the difference between the motor peak torque and the current HDC total torque. If so, the HDC total torque is adjusted to the sum of the current HDC total torque and the braking torque, and the braking torque is adjusted to 0; if not, the braking torque is adjusted to the current braking torque plus the current HDC total torque minus the motor peak torque, and the total torque is adjusted to the motor peak torque; if the accelerator pedal opening is greater than 0, it is also determined whether the driving torque is less than or equal to the HDC total torque. If so, the HDC total torque is adjusted to the difference between the current HDC total torque and the driving torque, and the driving torque is adjusted to 0; if not, the driving torque is adjusted to the difference between the current driving torque and the current HDC total torque, and the HDC total torque is adjusted to 0.

[0017] The driver is allowed to operate the brake pedal and accelerator pedal to control the vehicle, which effectively avoids the frequent exit of the HDC function and can recover the braking energy to the greatest extent, thereby improving the vehicle's economy.

[0018] Furthermore, the upper and lower limits of the HDC total torque are set according to the peak power and peak torque of the motor. When the HDC total torque changes and deviates from the upper or lower limit range, the motor is controlled to reduce or increase the HDC total torque. The change rate of the HDC total torque is also limited by the parameters of the vehicle speed closed-loop controller in the vehicle speed closed-loop control. When it is detected that the change rate of the HDC total torque exceeds the preset threshold, the parameters of the vehicle speed closed-loop controller are automatically adjusted.

[0019] By limiting the upper and lower limits of the total torque, the motor can be guaranteed to output the total torque within a safe range; by limiting the rate of change of the total torque, vehicle shaking caused by excessive changes in the total torque can be avoided.

[0020] Furthermore, before the vehicle enters the HDC mode, it is determined whether the HDC enabling conditions are met. The HDC enabling conditions include that the HDC function is turned on, the accelerator pedal and the brake pedal opening are 0, and the vehicle has no faults that affect the operation of HDC.

[0021] A vehicle includes an HDC controller, wherein the HDC controller includes a memory, a processor, and a computer program stored in the memory and executable on the processor. When the processor executes the computer program, a steep slope descent control method with global vehicle speed and gradient adaptation is implemented.

[0022] The beneficial effects of the present invention are as follows: the present invention is a pioneering invention, and the present invention can adaptively adjust the obtained feedforward torque according to the corresponding relationship between the current vehicle speed and the pre-acquired vehicle speed and motor torque, and superimpose the feedforward torque on the torque output value of the closed-loop control of the vehicle speed; in the corresponding relationship, the motor torque is positively correlated with the vehicle speed within the motor peak torque range, and at the same time, the vehicle speed is divided into three sections, namely, an acceleration interval, a HDC constant torque interval and a deceleration interval, as the vehicle speed increases. The HDC constant torque interval in the middle section corresponds to the HDC target speed interval, and the corresponding motor torque is a constant value, which is calculated based on the full load mass, the HDC target speed, and the HDC slope intermediate value, and the motor torque corresponding to the acceleration interval is smaller than the motor torque corresponding to the HDC constant torque interval, and the motor torque corresponding to the deceleration interval is larger than the motor torque corresponding to the HDC constant torque interval, and is limited by the external characteristics of the motor.

[0023] When the vehicle enters HDC mode and the speed is in the acceleration range, that is, the speed needs to be increased to reach the HDC target speed range, at this time, a motor torque smaller than the HDC constant torque range is given as the feedforward torque according to the corresponding relationship. In steep slope descent, the motor torque is used to counteract the reverse torque of the vehicle sliding down the slope. Therefore, a feedforward torque smaller than the motor torque corresponding to the HDC constant torque range will gradually accelerate the vehicle and increase the speed gradually until it enters the HDC constant torque range; the motor torque corresponding to the HDC constant torque range is a constant value, which is calculated based on the full load mass, HDC target speed, and HDC slope intermediate value. Therefore, in the process of increasing the vehicle speed, the feedforward torque (i.e., reverse braking torque) increases with the increase in vehicle speed. In this process, the speed will be controlled within the HDC target speed range in conjunction with the speed closed-loop fine-tuning error.

[0024] The motor torque corresponding to the deceleration interval is greater than the motor torque corresponding to the HDC constant torque interval. When the vehicle enters the HDC mode and the vehicle speed is in the deceleration interval, that is, the vehicle speed needs to be reduced to reach the HDC target speed interval, at this time, a motor torque greater than that corresponding to the HDC constant torque interval is given as the feedforward torque according to the corresponding relationship. Therefore, a feedforward torque greater than the motor torque corresponding to the HDC constant torque interval will gradually decelerate the vehicle and the speed will gradually decrease until it enters the HDC constant torque interval. In the process of vehicle speed reduction, the feedforward torque decreases as the vehicle speed decreases. In this process, the speed closed-loop fine-tuning error is combined to eventually control the vehicle speed within the HDC target speed interval.

[0025] The solution of the present invention effectively ensures that the vehicle speed when going downhill is steadily reduced or increased to the target speed as the motor torque increases or decreases. At the same time, the present invention does not rely on slope information and is suitable for commercial vehicles with separate head and compartment and large weight variations. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 It is a schematic diagram of a steep slope descent control process with global vehicle speed and gradient adaptation of the present invention;

[0027] Figure 2 It is a schematic diagram of a slope adaptive feed-forward torque curve designed by the present invention;

[0028] Figure 3 It is a schematic diagram of a slope adaptive feed-forward torque curve movement of the present invention;

[0029] Figure 4 It is a flow chart of realizing the closed-loop control logic of the driver according to the present invention. DETAILED DESCRIPTION

[0030] In order to make the purpose, technical solutions and advantages of the present invention more clear, the present invention is further described in detail below in conjunction with the accompanying drawings and embodiments.

[0031] The idea of ​​the present invention is that for a vehicle with an electric drive system with a fixed transmission ratio, when the vehicle enters the HDC function, the feedforward torque obtained for preventing the vehicle from accelerating down a slope is superimposed on the torque output value of the closed-loop speed control, so that the actual vehicle speed reaches the target speed smoothly. Considering that HDC is not dependent on the road slope and is suitable for commercial vehicles with a separated front and vehicle body and a large weight change, the feedforward torque can be adaptively adjusted through the corresponding relationship between the current actual vehicle speed and the pre-acquired vehicle speed and motor torque, and the feedforward torque can be superimposed on the torque output value of the closed-loop speed control. Torque output value; in the corresponding relationship between vehicle speed and motor torque, vehicle speed and motor torque are positively correlated within the motor peak torque range. At the same time, vehicle speed is divided into three sections: acceleration section, HDC constant torque section and deceleration section as vehicle speed increases. The HDC constant torque section in the middle section corresponds to the HDC target vehicle speed section. The motor feedforward torque corresponding to the HDC constant torque section is a constant value, which is calculated based on the full load mass, HDC target vehicle speed, and the HDC slope middle value; among them, the HDC slope middle value is the slope of the ramp with the highest probability of appearing in the vehicle working environment. The HDC mode is adapted to a certain range of slopes. The vehicle's HDC mode can only function effectively on slopes within this range. Ramps with a maximum slope exceeding this range are abnormal extreme slope road conditions, and the drive motor cannot guarantee sufficient reverse torque to control the vehicle speed within the target speed. The vehicle's ability to glide on slopes below the minimum slope in this range is limited, and HDC will not intervene normally. Using the slope of the steepest slope with the highest probability of occurring in the vehicle's working environment as the middle value of the HDC slope can ensure that the vehicle can descend smoothly in the HDC mode in most cases. The motor torque corresponding to the acceleration interval is smaller than the motor torque corresponding to the HDC constant torque interval. When the vehicle speed is in the acceleration interval, a feedforward torque smaller than the motor torque corresponding to the HDC constant torque interval will cause the vehicle to gradually accelerate and cooperate with the speed closed-loop control to smoothly control the vehicle speed to the target speed; the motor torque corresponding to the deceleration interval is greater than the motor torque corresponding to the HDC constant torque interval. When the vehicle speed is in the deceleration interval, a feedforward torque greater than the motor torque corresponding to the HDC constant torque interval will cause the vehicle to gradually decelerate and cooperate with the speed closed-loop control to smoothly control the vehicle speed to the target speed.

[0032] Method Example:

[0033] The present embodiment provides a steep slope descent control method with full-range vehicle speed and gradient adaptation, comprising the following steps: first, determining the feedforward torque through vehicle gradient adaptive feedforward control; then, determining the torque output value of vehicle speed closed-loop control through vehicle mass adaptive feedback control, and superimposing the feedforward torque on the feedback torque to control the vehicle speed to the HDC target speed.

[0034] Specifically, the vehicle slope adaptive feedforward control is that the vehicle obtains the feedforward torque according to the corresponding motor torque based on the current vehicle speed and the pre-acquired correspondence between the vehicle speed and the motor torque. The vehicle speed and motor torque in the corresponding relationship are positively correlated within the motor peak torque range, and the vehicle speed in the corresponding relationship is divided into an acceleration interval, a HDC constant torque interval, and a deceleration interval as the vehicle speed increases.

[0035] Now combined Figure 2 , introduces a design method for the corresponding relationship between vehicle speed and motor torque. In the figure, the horizontal axis represents the vehicle speed, the vertical axis represents the motor torque, and the curve represents the slope adaptive feedforward torque curve. The horizontal axis is divided into three sections, namely, the acceleration interval, the HDC constant torque interval and the deceleration interval, as the vehicle speed increases. Within the peak torque range of the motor, when the vehicle speed is in the acceleration interval and the deceleration interval, the corresponding motor torque increases linearly with the increase of the vehicle speed, and when the vehicle speed is in the HDC constant torque interval, the corresponding motor torque remains constant. Among them, the HDC constant torque interval corresponds to the HDC target vehicle speed interval. The motor feedforward torque corresponding to the HDC constant torque interval is a constant value, which is determined according to the full load mass, the HDC target vehicle speed, and the HDC slope intermediate value. This parameter has been solidified before the vehicle leaves the factory. The present invention uses the slope of the steep slope with the highest probability of appearing in the vehicle working environment as the HDC slope intermediate value to ensure that the vehicle can smoothly go downhill in the HDC mode under most working conditions. As other embodiments, the HDC slope intermediate value can also select other slope values ​​within the slope range adapted by HDC. The motor torque corresponding to the acceleration interval (the reverse torque used to prevent the vehicle from accelerating down the slope) is smaller than the motor torque corresponding to the HDC constant torque interval. In this interval, the motor torque decreases linearly to 0 as the vehicle speed decreases, ensuring that when the actual vehicle speed is less than the HDC target speed, the vehicle can accelerate smoothly as the motor torque decreases, and the vehicle speed gradually increases to the HDC target speed interval; the motor torque corresponding to the deceleration interval is larger than the motor torque in the HDC constant torque interval. In this interval, the motor feedforward torque increases linearly to the peak torque as the vehicle speed increases, and is limited within the motor external characteristics, ensuring that when the actual vehicle speed is greater than the target speed, the vehicle can decelerate smoothly as the feedforward torque increases, and the vehicle speed gradually decreases to the HDC target speed interval.

[0036] As another embodiment, the HDC target vehicle speed is determined by global vehicle speed linear control, and then the HDC target vehicle speed range is determined.

[0037] Specifically, since the vehicle is equipped with an electric drive system with a fixed transmission ratio, there is no risk of automatic upshifting, and the vehicle can be linearly controlled according to the full-range vehicle speed to fully meet the driver's driving intention. Full-range vehicle speed linear control determines the HDC target speed according to the vehicle speed when the vehicle enters the HDC mode. If the steep slope descent function switch is turned on first, and then the accelerator pedal and the brake pedal are released, the vehicle speed at the time of releasing the accelerator pedal and the brake pedal is used as the HDC target speed. If the accelerator pedal and the brake pedal are released first, and then the steep slope descent function switch is turned on, the vehicle speed at the time of turning on the steep slope descent function switch is used as the HDC target speed; further, according to the HDC target speed and the speed error range that has been solidified before leaving the factory, the HDC target speed range is determined, that is, [HDC target speed-speed error threshold, HDC target speed+speed error threshold] is used as the HDC target speed range. The speed error range should be relatively small, such as less than 1km / h, and the difference between the HDC target speed and the speed error range should be greater than 0.

[0038] Specifically, the HDC minimum speed and the HDC maximum speed can be set. If the vehicle speed when the vehicle enters the HDC mode is less than the HDC minimum speed, the HDC minimum speed will be used as the HDC target speed; if the vehicle speed is greater than the HDC maximum speed, the HDC maximum speed will be used as the HDC target speed; if the vehicle speed is between the HDC minimum speed and the HDC maximum speed, the speed will be used as the HDC target speed.

[0039] As the driver's intention changes, the HDC target speed is adjusted, and the slope adaptive feedforward torque curve should move with the change of the HDC target speed, such as Figure 3 As shown in the figure, a law of movement of the slope adaptive feed-forward torque curve is given, which is specifically manifested as follows: if the HDC target vehicle speed increases, the motor torque corresponding to the larger HDC target vehicle speed is smaller, that is, the slope adaptive feed-forward torque curve moves horizontally to the right, but will not exceed the slope adaptive feed-forward torque curve corresponding to the HDC maximum vehicle speed; if the HDC target vehicle speed decreases, the motor torque corresponding to the smaller HDC target vehicle speed is larger, that is, the slope adaptive feed-forward torque curve moves horizontally to the left, but will not exceed the slope adaptive feed-forward torque curve corresponding to the HDC minimum vehicle speed; during the change of the slope adaptive feed-forward torque curve, the motor torque corresponding to the HDC constant torque interval remains unchanged.

[0040] As other implementation methods, the motor torque in the HDC constant torque interval can also be adjusted near a constant value and appropriately smoothed, but the range of variation should not be too large; the slope of the slope adaptive feed-forward torque curve corresponding to the acceleration interval can be adjusted according to actual needs, and can be appropriately smoothed on this basis; in the deceleration interval, the slope of the slope adaptive feed-forward torque curve linearly increasing from the constant value of the motor torque in the HDC constant torque interval to the peak torque can be adjusted according to actual needs, and can be appropriately smoothed on this basis.

[0041] In the vehicle mass adaptive feedback control after obtaining the feedforward torque, the torque output value of the speed closed loop, i.e. the feedback torque, is determined based on the difference between the current vehicle speed and the target vehicle speed and the difference is subjected to proportional-integral control. This further corrects the feedforward torque steady-state error caused by mass grading error or slope change, thereby achieving adaptive control of different vehicle masses.

[0042] In the quality adaptive feedback control process, the parameters of the closed-loop controller are designed, such as the proportional-integral coefficient, to limit the absolute value of the feedback torque to be less than or equal to the absolute value of the feedforward torque.

[0043] After the feedback torque is obtained, the sum of the feedforward torque and the feedback torque is taken as the HDC total torque through the HDC total torque control.

[0044] During the HDC total torque control process, the HDC total torque is also subject to gradient limitation and amplitude limitation. The gradient limitation limits the change rate of the HDC total torque. When it is detected that the change rate of the HDC total torque exceeds the preset threshold, the change rate of the HDC total torque is adjusted to the preset threshold to prevent vehicle shaking caused by excessive changes in the HDC total torque. The amplitude limitation sets the upper and lower limits of the HDC total torque based on the peak power and peak torque of the motor. When the HDC total torque deviates from the upper or lower limit of the HDC total torque during the change process, the motor is controlled to reduce or increase the HDC total torque to ensure that the motor torque changes within a safe torque range.

[0045] As another embodiment, in the process of obtaining the feed-forward torque, vehicle mass graded control is also performed to correct the excessive feed-forward torque caused by changes in vehicle load and a large difference from the fully loaded mass.

[0046] Specifically, vehicle mass grading control is the driver setting the vehicle mass level through the handle, function button or central control screen according to the actual load of the vehicle, and multiplying the motor torque obtained according to the corresponding relationship by the mass coefficient to obtain the feedforward torque. Among them, the vehicle is divided into several mass levels from no load to full load, such as no load, 1 / 4 load, 2 / 4 load, 3 / 4 load and full load. If the driver judges that the actual load of the vehicle is close to 2 / 4 load, it is set according to 2 / 4 load; the mass coefficient is the ratio of the vehicle mass corresponding to the vehicle mass level to the full load mass.

[0047] As other implementations, HDC enabling judgment and driver closed-loop control steps are also provided. The overall process is as follows: Figure 1 shown.

[0048] Specifically, the specific conditions for enabling HDC are: the hill descent control switch is turned on, the accelerator pedal opening and the brake pedal opening are 0, and the vehicle has no faults that affect the operation of HDC (for example, motor failure, communication failure).

[0049] Specifically, the driver closed-loop control allows the driver to modify the HDC total torque by operating the accelerator pedal and the brake pedal without turning off the steep hill descent function switch, and ensures that the HDC function will not be exited. Figure 4 A driver closed-loop control process shown in the figure first determines whether the brake pedal opening is 0. When the brake pedal opening is not 0, it means that the driver wants to control the vehicle through the brake pedal at this time, so it is necessary to further determine whether the braking torque used for the vehicle braking system response is less than or equal to the difference between the motor peak torque and the current HDC total torque. If so, the HDC total torque is adjusted to the sum of the current HDC total torque and the braking torque, and the braking torque is adjusted to 0 so that the motor only outputs the HDC total torque. If not, the braking torque is adjusted to the current braking torque plus the current HDC total torque minus the motor peak torque, and the HDC total torque is adjusted to the motor peak torque, which can effectively reduce the braking torque used for the vehicle braking system response; wherein, the braking torque is obtained according to the current brake pedal opening and the vehicle speed. If the brake pedal opening is 0, further determine whether the accelerator pedal opening is 0. If not, it means that the driver wants to control the vehicle through the accelerator pedal. Further determine whether the driving torque that the driver wants the vehicle to accelerate in response to is less than or equal to the HDC total torque. If so, adjust the HDC total torque to the difference between the current HDC total torque and the driving torque, and adjust the driving torque to 0; if not, adjust the driving torque to the difference between the current driving torque and the current HDC total torque, and adjust the HDC total torque to 0; wherein the driving torque is obtained according to the current accelerator pedal opening and vehicle speed. If the brake pedal opening and the accelerator pedal opening are both 0, the HDC total torque remains unchanged.

[0050] Vehicle Example:

[0051] This embodiment provides a vehicle which, when entering the steep slope descent function, adopts a steep slope descent control method with global vehicle speed and slope adaptiveness as described in the method embodiment. Since the introduction of this method is clear enough, it will not be repeated here.

[0052] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention rather than to limit it. Although the present invention has been described in detail with reference to the above embodiments, ordinary technicians in the relevant field should understand that the specific implementation methods of the present invention can still be modified or replaced by equivalents. Any modification or equivalent replacement that does not depart from the spirit and scope of the present invention should be covered within the scope of protection of the claims of the present invention.

Claims

1. A global vehicle speed and gradient adaptive steep slope descent control method, characterized in that: In HDC mode, the vehicle obtains a feedforward torque according to the corresponding motor torque based on the current vehicle speed and the pre-acquired correspondence between the vehicle speed and the motor torque, and the feedforward torque is superimposed on the torque output value of the closed-loop speed control to control the vehicle to the HDC target speed. The vehicle speed and the motor torque in the corresponding relationship are positively correlated within the motor peak torque range, and the vehicle speed in the corresponding relationship is divided into an acceleration interval, an HDC constant torque interval and a deceleration interval as the vehicle speed increases; The HDC constant torque range corresponds to the HDC target vehicle speed range; The motor torque corresponding to the HDC constant torque interval is a constant value, which is calculated based on the full load mass, the HDC target vehicle speed, and the HDC slope intermediate value; the HDC slope intermediate value is the slope value between the maximum slope and the minimum slope within the slope range adapted by the HDC mode.

2. The global vehicle speed and gradient adaptive steep slope descent control method according to claim 1 is characterized in that: In the corresponding relationship, the motor torque corresponding to the acceleration interval decreases linearly from the constant value of the motor torque corresponding to the HDC constant torque interval to 0 as the vehicle speed decreases; the motor torque corresponding to the deceleration interval increases linearly from the constant value of the motor torque corresponding to the HDC constant torque interval to the motor peak torque as the vehicle speed increases.

3. The global vehicle speed and gradient adaptive steep slope descent control method according to claim 1 is characterized in that: There are at least two corresponding relationships, and the corresponding corresponding relationship is selected according to the HDC target vehicle speed. The HDC target vehicle speed is determined according to the vehicle speed when the vehicle enters the HDC mode, and the HDC target vehicle speed range in the corresponding relationship corresponding to the HDC target vehicle speed is determined according to the HDC target vehicle speed and a pre-set vehicle speed error range. The corresponding relationship corresponding to the large HDC target vehicle speed has the following characteristics compared to the corresponding relationship corresponding to the small HDC target vehicle speed: in the acceleration interval and the deceleration interval, the motor torque corresponding to the same vehicle speed is smaller.

4. The global vehicle speed and gradient adaptive steep slope descent control method according to claim 1, characterized in that: The HDC slope median value is the slope of the slope with the highest probability of appearing in the working condition.

5. The global vehicle speed and gradient adaptive steep slope descent control method according to claim 1, characterized in that: The corresponding motor torque obtained is multiplied by a mass coefficient and used as the feedforward torque; the mass coefficient is determined according to the ratio of the current actual mass of the vehicle to the full-load mass.

6. The global vehicle speed and gradient adaptive steep slope descent control method according to claim 1 is characterized in that: The parameters of the vehicle speed closed-loop controller in the vehicle speed closed-loop control are parameters that make the absolute value of the torque output value of the vehicle speed closed-loop control less than or equal to the absolute value of the feedforward torque.

7. The global vehicle speed and gradient adaptive steep slope descent control method according to claim 2 is characterized in that: After the feedforward torque is superimposed on the torque output value of the vehicle speed closed-loop control to obtain the HDC total torque for driving the motor response, the opening of the accelerator pedal and the brake pedal is also determined; if the brake pedal opening is greater than 0, it is also determined whether the braking torque for the vehicle braking system response obtained according to the brake pedal is less than or equal to the difference between the motor peak torque and the current HDC total torque. If so, the HDC total torque is adjusted to the sum of the current HDC total torque and the braking torque, and the braking torque is adjusted to 0; if not, the braking torque is adjusted to the current braking torque added to the current HDC total torque minus the motor peak torque, and the total torque is adjusted to the motor peak torque; if the accelerator pedal opening is greater than 0, it is also determined whether the driving torque is less than or equal to the HDC total torque. If so, the HDC total torque is adjusted to the difference between the current HDC total torque and the driving torque, and the driving torque is adjusted to 0; if not, the driving torque is adjusted to the difference between the current driving torque and the current HDC total torque, and the HDC total torque is adjusted to 0.

8. The global vehicle speed and gradient adaptive steep slope descent control method according to claim 7 is characterized in that: The upper and lower limits of the HDC total torque are also set according to the peak power and peak torque of the motor. When the HDC total torque changes and deviates from the upper or lower limit range, the motor is controlled to reduce or increase the HDC total torque. The change rate of the HDC total torque is also limited by the parameters of the vehicle speed closed-loop controller in the vehicle speed closed-loop control. When it is detected that the change rate of the HDC total torque exceeds a preset threshold, the parameters of the vehicle speed closed-loop controller are automatically adjusted.

9. The global vehicle speed and gradient adaptive steep slope descent control method according to claim 1, characterized in that: Before the vehicle enters the HDC mode, it is also determined whether the HDC enabling conditions are met. The HDC enabling conditions include that the HDC function is turned on, the accelerator pedal and the brake pedal opening are 0, and the vehicle has no faults that affect the operation of the HDC.

10. A vehicle, comprising an HDC controller, characterized in that: The HDC controller includes a memory, a processor, and a computer program stored in the memory and executable on the processor. When the processor executes the computer program, the steep slope descent control method with global vehicle speed and gradient adaptation according to any one of claims 1 to 9 is implemented.

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