Patent Description:
The present invention relates to the technical field of anti-slip control, and in particular to an anti-skid control method for transfer case.

Under a track slip working condition, in response to the main driving wheel of a vehicle equipped with a timely four-wheel-drive transfer case generate track slip, anti-skid control needs to be implemented on the transfer case, that is, the engagement torque of the transfer case needs to be increased or decreased currently to achieve reasonable distribution of driving torques of a front axle and a rear axle of the vehicle again, thereby eliminating an over track slip state and an under track slip state of the main driving wheel to improve the traction performance and stability of the vehicle.

Currently, the anti-skid control for the four-wheel-drive transfer case is mainly based on threshold value control, that is, according to the magnitude of a speed difference between the front axle and the rear axle of the vehicle, an anti-skid control coefficient and a specific engagement torque value of the transfer case are determined; in response to the speed difference being greater than a preset threshold value, the engagement torque of the transfer case is quickly increased to achieve four-wheel-drive torque distribution; and in response to the speed difference being less than the preset threshold value, the engagement torque of the transfer case is decreased to achieve high-efficiency two-wheel-drive driving. However, in response to the vehicle running on a wet and slippery road surface in an acceleration mode, frequent and repeated engagement torque fluctuation, anti-slip fluctuation and longitudinal acceleration fluctuation of the transfer case are likely to occur, so that the judgment relationship between the speed difference and the threshold value is frequently and repeatedly changed, which is disadvantages to the driving performance and stability of the whole vehicle.

Document <CIT> discloses an anti-skid control method for a transfer case.

In summary, there is an urgent need to configure an anti-skid control method for transfer case to solve the above-mentioned problems.

At least some embodiments of the present invention provides an anti-skid control method for transfer case, which is configured to adjust an engagement control torque of the transfer case in real time while avoiding the influence of anti-slip fluctuation and torque fluctuation of a vehicle to ensure the driving performance and stability of the whole vehicle.

The present invention utilizes the following technical solutions:
An embodiment of present invention provides an anti-skid control method for transfer case, including the following steps:.

An embodiment of present invention provides an electronic device, including:.

An embodiment of present invention further provides a computer-readable storage medium, wherein the computer-readable storage medium is configured to store a computer program, and in response to executed by a processor, the computer program implements the anti-skid control method for transfer case as claimed in an embodiment of the present invention.

Throughout the specification, the same reference signs denote the same elements.

In the present embodiment, an anti-skid control method for transfer case is provided, in which the influence on the fluctuation of an engagement control torque of the transfer case of a vehicle under various conditions, such as acceleration, steering, lateral deviation and other conditions, are comprehensively considered, and multiple control parameters of the vehicle can be adjusted in real time, thereby realizing a stable anti-slip closed-loop control function of the vehicle, to avoid trackslip of the vehicle to ensure the driving performance and stability of the vehicle. In the present embodiment, the vehicle is a vehicle equipped with a timely four-wheel-drive transfer case.

For example, as shown in <FIG>, the anti-skid control method for transfer case includes the following steps:.

In step S10: calculating a target speed of a main driving shaft: vm, target = max(vs, target, vmin), and vm, target denotes the target speed of the main driving shaft, vs, target denotes the speed of the main driving shaft in response to the influence of the steering of a vehicle and the lateral deviation of a tire being considered, and vmin denotes a minimum speed of the vehicle at different vehicle speeds to avoid a wheel speed precision error and a jitter phenomenon of the vehicle under a starting low-speed driving condition;.

In step S20: determining an anti-skid control condition: in response to vm > vm, target (<NUM>+λ<NUM>), and a time period t of keeping vm > vm, target (<NUM> + λ<NUM>) is greater than or equal to a time period t<NUM>, starting an anti-skid control, and t<NUM> is related to the acceleration of the main driving shaft, vm denotes an average value of the rotating speeds of two wheels at two ends of the main driving shaft, and λ<NUM> denotes a trigger threshold offset of an anti-skid control function under a trackslip condition;
in an anti-skid control starting state, in response to an engagement control torque Ttarget of the transfer case of the vehicle being equal to <NUM>, and the time period t of keeping Ttarget = <NUM> is greater than or equal to a time period t<NUM>, exiting the anti-skid control, and t<NUM> is a calibration value; and.

In step S30: calculating the engagement control torque Ttarget of the transfer case: Ttarget = kp△v, m+kl ∫ △v, m, and kp and kl both denote a corrected proportional integral control parameters obtained by correcting a control parameter factor b of the vehicle in an over-trackslip state and an under-trackslip state, kp and kl may be adapatively adjusted under a linear or steering working condition of the vehicle, Δv, m denotes a speed control deviation of the main driving shaft, and △v, m = vm - vm, target, therefore after the vehicle starts the anti-skid control function, the engagement control torque of the transfer case may be increased or decreased according to the value of Ttarget, which is calculated in real time according to Ttarget = Kp△v, m+kl ∫ △v, m, so as to adjust the Ttarget in real time, and accordingly, trackslip of the vehicle may be avoided.

By means of calculating the target speed of the main driving shaft: vm, target = max(vs, target, vmin), in response to vm > vm, target (<NUM> + λ<NUM>), and the time t of keeping vm > vm, target (<NUM> + λ<NUM>) is greater than or equal to t<NUM>, the anti-skid control is started; in the anti-skid control starting state, in response to the engagement control torque Ttarget of the transfer case of the vehicle being equal to <NUM>, and the time t of keeping Ttarget = <NUM> is greater than or equal to t<NUM>, the anti-skid control is exited; and after the vehicle starts the anti-skid control, the engagement control torque for transfer case can be increased or decreased based on the value of Ttarget, which is calculated through Ttarget = kp△v, m+kl ∫ △v, m to avoid trackslip of the vehicle. In this way, the driving torques of front and rear axles of the vehicle are reasonably distributed again to reduce the trackslip state of the main driving wheel and to ensure the traction performance and stability of the vehicle.

During the process of calculating the target speed vm, target of the main driving shaft, the influence of the steering of the vehicle and the lateral deviation of the tire is considered, and the wheel speed precision error and the jitter phenomenon of the vehicle under the starting low-speed driving working condition are avoided; and both the corrected proportional integral control parameters kp and kl involved in the calculation of the engagement control torque Ttarget of the transfer case are obtained by correcting the control parameter factor of the vehicle in the over-trackslip state and the under-trackslip state, and kp and kl are configured to be adapatively adjusted under the linear or steering working condition of the vehicle, therefore anti-slip fluctuation and torque fluctuation of the vehicle under the trackslip working condition can be effectively avoided, thereby adjusting the engagement control torque Ttarget of the transfer case in real time, and realizing an intelligent timely four-wheel-drive anti-slip closed-loop control function. In this way, in response to the vehicle runs on a wet and slippery road surface in an acceleration mode, frequent and repeated engagement torque fluctuation, anti-slip fluctuation and longitudinal acceleration fluctuation of the transfer case, which are disadvantages to the driving performance and stability of the whole vehicle, are avoided.

For example, in response to △v, m > <NUM>, the main driving shaft being in the under-trackslip state, the engagement control torque Ttarget of the transfer case is configured to increase currently, and the corrected proportional integral control parameters kp and kl are both positive values currently; and in response to △v, m < <NUM>, the main driving shaft being in the over-trackslip state, the control parameter factor b is determined based on the specific driving condition of the vehicle currently to decrease the control parameter to reduce the engagement control torque Ttarget of the transfer case and to reduce the descent speed of the engagement control torque Ttarget, thereby prolonging the anti-skid control time to avoid the problem of rotating speed fluctuation and acceleration fluctuation of the vehicle, which are caused by the fluctuation of the engagement control torque Ttarget.

For example, as shown in <FIG>, the step S25 is further included between the step S20 and the step S30: calculating the corrected proportional integral control parameters kp and kl: <MAT> <MAT> and kp0 and kl0 denote proportional integral control parameters.

For example, in the step S25, in response to the vehicle is in a low-speed linear acceleration driving condition, since the response of the engagement control torque Ttarget of the transfer case is relatively slow and the control precision is relatively low, in order to avoid the phenomena of torque fluctuation, rotating speed fluctuation and other conditions caused by frequent reciprocating of anti-skid control, the decrease of the engagement control torque Ttarget in the anti-skid control of the transfer case can be slowed down by adjusting the control parameter factor b; and the control parameter factor <MAT>; and <NUM> ≤ b ≤ <NUM>, amin denotes a minimum accelerator opening degree of the vehicle, ak denotes an accelerator opening degree at the current time, athrsh denotes an accelerator opening degree change threshold value of the vehicle, and athrsh is a calibration value.

For example, the minimum accelerator opening degree of the vehicle in the trackslip state is
<MAT>
wherein amin, k-<NUM> denotes the minimum accelerator opening degree of the vehicle at the previous time, and TCS denotes a traction control system of the vehicle.

For example, in the step S25, in response to the vehicle is a high-speed acceleration driving condition, the control parameter factor b = max(bδ, bv, bsw, bcoast); wherein bδ denotes a steering wheel rotation angle control factor of the vehicle, and <NUM>≤bδ≤<NUM>, bv denotes a vehicle speed control parameter factor of the vehicle, and <NUM>≤bv≤<NUM>, bsw denotes a control parameter factor of the vehicle under a steering condition, bcoast denotes a slip control parameter factor of the vehicle, in response to the vehicle is in a slip driving condition and performing the anti-skid control, the slip control parameter factor bcoast being equal to <NUM>, and in response to the vehicle is in the slip driving condition and exits anti-skid control, the slip control parameter factor bcoast being equal to <NUM>.

Under a steering acceleration driving condition, the steering wheel rotation angle control factor bδ of the vehicle increases with the increase of the absolute value of a steering wheel rotation angle, the absolute value of a lateral acceleration and the absolute value of a yaw rate, thereby avoiding a steering braking phenomenon caused by the excessively large engagement control torque of the transfer case under the steering working condition, that is, the calculation formula of the steering wheel rotation angle control factor bδ of the vehicle is as follow: <MAT> and δ denotes a steering wheel rotation angle of the vehicle, and the unit of the steering wheel rotation angle is rad; both δ<NUM> and δ<NUM> denote calibration values of the steering wheel rotation angle of the vehicle, and δ<NUM> and δ<NUM> are determined values, and the unit of the calibration value is rad; and both bδ1 and bδ2 denote calibration values of a steering wheel rotation angle control parameter of the vehicle, and bδ1 and bδ2 are determined values.

For example, under a high-speed acceleration driving condition, the vehicle speed control parameter factor bv decreases with the increase of the vehicle speed, thereby avoiding excessive intervention in the anti-skid control under the high-speed acceleration driving condition, that is, the calculation formula of the vehicle speed control parameter factor bv of the vehicle is as follow: <MAT> and v denotes a vehicle speed of the vehicle, and the unit of the vehicle speed is m/s; both v<NUM> and v<NUM> denote speed calibration values of the vehicle, v<NUM> and v<NUM> are determined values, and the unit of the speed calibration value is m/s; and both bv1 and bv2 denote calibration values of a vehicle speed control parameter of the vehicle, and bv1 and bv2 are determined values.

The calculation formula of the control parameter factor bsw of the vehicle under the steering working condition is as follow: <MAT> and bay denotes a lateral acceleration control parameter factor, by denotes a yaw rate control parameter factor, and bT denotes a torque control parameter factor under a steering acceleration condition.

For example, the calculation formula of the lateral acceleration control parameter factor bay is as follow: <MAT> and ay denotes a lateral acceleration of the vehicle, and the unit is of the lateral acceleration is m/s<NUM>; both ay<NUM> and ay<NUM> denote lateral acceleration calibration values of the vehicle, ay<NUM> and ay<NUM> are determined values, and the unit is of the lateral acceleration calibration value is m/s<NUM>; and both bay1 and bay2 denote calibration values of a lateral acceleration control parameter of the vehicle, and bay1 and bay2 are determined values.

For example, the calculation formula of the yaw rate control parameter factor by is as follow: <MAT> and y denotes a yaw rate of the vehicle, and the unit of the yaw rate is rad/s; both y<NUM> and y<NUM> denote yaw rate calibration values of the vehicle, y<NUM> and y<NUM> are determined values, and the unit of the yaw rate calibration value is rad/s; and both by1 and by2 denote calibration values of a yaw rate control parameter of the vehicle, and by1 and by2 are determined values.

For example, since the torque control parameter factor bT under the steering acceleration condition increases along with the increase of the driving torque of the driving shaft, that is, the calculation formula of bT is as follow: <MAT> and T denotes a driving torque of the vehicle, and the unit of the driving torque is N·m; both T<NUM> and T<NUM> denote driving torque calibration values of the vehicle, T<NUM> and T<NUM> are determined values, and the unit of the driving torque calibration value is N·m; and both bT1 and bT2 denote calibration values of a driving torque control parameter of the vehicle, and bT1 and bT2 are determined values.

For example, in response to the main driving shaft is a rear axle, the influence of the steering of the vehicle and the lateral deviation of the tire being considered at the same time: <MAT>.

For example, in order to avoid the wheel speed precision error and the jitter phenomenon of the vehicle under the low-speed driving condition such as starting, the calculation formula of the minimum speed vmin of the vehicle at different vehicle speeds is as follow: <MAT> and both vx0 and vy0, min are calibration values, vx0 = [<NUM><NUM><NUM><NUM><NUM><NUM>], vy0, min = [ <NUM><NUM><NUM><NUM><NUM>].

For example, in order to enable the vehicle to quickly start the anti-skid control under a severe trackslip condition, it is judged that the time t<NUM> is related to the acceleration of the main driving shaft, and the calculation formula of the time t<NUM> is as follow: <MAT> and aaxle denotes an actual acceleration of the main driving shaft, and the unit of the actual acceleration is m/s<NUM>; both a<NUM> and a<NUM> denote acceleration calibration values of the main driving shaft, and the unit of the acceleration calibration value is m/s<NUM>, and t<NUM> and t<NUM> denote time calibration values, and the unit of the time calibration value is s.

The control process of the anti-skid control method for transfer case in the present embodiment is as follows: as shown in <FIG>, the front axle is taken as the main driving shaft: first, vs, target is calculated through vs, target = max ((vm,R cos θ + γL sin θ)(<NUM> + γ<NUM>), vm,R), and vm, R denotes the speed of the rear axle, that is, the average value of the rotating speeds of the two wheels at the two ends of the rear axle; and vmin is calculated through , and then the target speed vm, target of the front axle is calculated through vm, target = max(vs, target, vmin). vmin = MAP(vx<NUM>, vy<NUM>,min).

Then, t<NUM> is calculated through <MAT> and through vm > vm, target (<NUM> + λ<NUM>), and the time t of keeping vm > vm, target (<NUM> + λ<NUM>) is greater than or equal to a time t<NUM>, it is judged that the vehicle needs to perform anti-skid control, that is, anti-skid control is started currently, wherein vm denotes the speed of the front axle, that is, the average value of the rotating speeds of the two wheels at the two ends of the front axle.

Next, it is judged through △v, m > <NUM> or Δv, m < <NUM> that, the vehicle needs to increase the engagement control torque Ttarget of the transfer case or decrease the engagement control torque Ttarget of the transfer case.

Afterwards, the control parameter factor b is calculated through the working condition of the vehicle: in response to the vehicle is in the low-speed linear acceleration driving condition, the control parameter factor b being calculated through <MAT>; or, in response to the vehicle is in the high-speed acceleration driving condition, the control parameter factor b being calculated through <MAT> Then, the corrected proportional integral control parameters kp and kl are respectively calculated through <MAT> and <MAT>; and a specific numerical value of the engagement control torque Ttarget of the transfer case, which needs to be adjusted in real time under different working conditions, is calculated through Ttarget = kpΔv,m + kI ∫ Δv,m, and the engagement control torque Ttarget of the transfer case is correspondingly increased or decreased.

Finally, in the anti-skid control starting state, in response to the engagement control torque Ttarget of the transfer case of the vehicle is equal to <NUM>, and the time t of keeping Ttarget = <NUM> being greater than or equal to t<NUM>, the anti-skid control is exited to complete the anti-skid control process of the whole vehicle.

Referring to <FIG>, it shows a schematic structural diagram of an electronic device (e.g., a terminal device or a server in <FIG>) <NUM> suitable for implementing the embodiments of the present invention. The terminal device in the embodiments of the present invention include, but is not limited to, mobile terminals such as a mobile phone, a notebook computer, a digital broadcast receiver, a PDA (Personal Digital Assistant), a PAD (Tablet computer), a PMP (Portable Multimedia Player), an on-board terminal (e.g., an on-board navigation terminal), and other mobile terminals, and fixed terminals such as a digital TV, a desktop computer, and other fixed terminals. The electronic device shown in <FIG> is an example, and should not bring any limitation to the functions and use ranges of the embodiments of the present invention.

As shown in <FIG>, the electronic device <NUM> include a processing apparatus (e.g., a central processor, a graphics processor, and other processing apparatus) <NUM>, which execute multiple appropriate actions and processing based on programs stored in a read only memory (ROM) <NUM> or programs loaded into a random access memory (RAM) <NUM> from a storage apparatus <NUM>. In the RAM <NUM>, various programs and data required for the operations of the electronic device <NUM> are also stored. The processing apparatus <NUM>, the ROM <NUM> and the RAM <NUM> are connected with each other through a bus <NUM>. An input/output (I/O) interface <NUM> is also connected to the bus <NUM>.

Generally, the following apparatuses are configured to be connected to the I/O interface <NUM>: an input apparatus <NUM>, including, for example, a touch screen, a touchpad, a keyboard, a mouse, a camera, a microphone, an accelerometer, a gyroscope and other input apparatuses; an output apparatus <NUM>, including, for example, a liquid crystal display (LCD), a loudspeaker, a vibrator, and the like; the storage apparatus <NUM>, including, for example, a magnetic tape, a hard disk, and the like; and a communication apparatus <NUM>. The communication apparatus <NUM> allow the electronic device <NUM> to perform wired or wireless communication with other devices to exchange data. Although <FIG> shows the electronic device <NUM> is configured with multiple apparatuses, it should be understood that, it is not required to implement or have all illustrated apparatuses. More or fewer apparatuses are configured to be alternatively implemented or provided.

For example, according to the embodiments of the present invention, the process mentioned above with reference to the flowchart can be implemented as a computer software program. For example, the embodiments of the present invention include a computer program product, which includes a computer program carried on a non-transient computer-readable medium, and the computer program includes a program code, which is configured to execute the method shown in the flowchart.

The computer-readable medium can be contained in the electronic device; and the computer-readable medium can also exist alone, and is not assembled in the electronic device.

The computer-readable medium carries at least one program, and in response to being executed, the at least one program execute the following steps:.

Claim 1:
An anti-slip control method of transfer case, characterized in that it comprises:
S10: calculating a target speed of a main driving shaft through the following formula: vm, target = max(vs, target, vmin), wherein vm, target denotes the target speed of the main driving shaft, vs, target denotes the speed of the main driving shaft in response to the influence of the steering of a vehicle and the lateral deviation of a tire being considered, and vmin denotes a minimum speed of the vehicle to avoid a wheel speed precision error and a jitter phenomenon of the vehicle under a starting low-speed driving condition;
S20: determining an anti-slip control condition through the following mode: in response to determining that vm > vm, target (<NUM>+λ<NUM>), and a time period t of keeping vm > vm, target (<NUM>+λ<NUM>) is greater than or equal to a time period t<NUM>, starting an anti-slip control, and t<NUM> is related to the acceleration of the main driving shaft, vm denotes an average value of the rotating speeds of two wheels at two ends of the main driving shaft, and λ<NUM> denotes a trigger threshold offset of an anti-slip control function under a trackslip condition;
in an anti-slip control starting state, in response to determining that an engagement control torque Ttarget of the transfer case of the vehicle is equal to <NUM>, and the time period t of keeping Ttarget = <NUM> is greater than or equal to a time period t<NUM>, exiting the anti-slip control, and t<NUM> is a calibration value;
S30: calculating the engagement control torque Ttarget of the transfer case through the following formula: Ttarget = Kp△v, m+kl ∫ △v, m, and kp and kl denote a corrected proportional integral control parameters obtained by correcting a control parameter factor b of the vehicle in an over-trackslip state and an under-trackslip state, △v, m denotes a speed control deviation of the main driving shaft, and △v, m = vm - vm, target.