KR102323962B1 - Shift control method and system under rapid acceleration of vehicle in low friction roads - Google Patents

Abstract

The present invention provides a method for controlling a shift during rapid acceleration of a vehicle on a low-friction road, which can improve starting performance of a vehicle by alleviating a sudden increase in wheel torque during the rapid acceleration in a vehicle traveling on the low-friction road surface, and a system thereof. The method for controlling the shift in the vehicle according to the present invention comprises the following steps of: determining whether a current vehicle speed of the vehicle is equal to or less than a set value; determining whether the vehicle is in a status of rapid acceleration when the vehicle speed of the vehicle is equal to or less than the set value; determining whether a vehicle wheel slips when the vehicle is in the status of rapid acceleration; determining whether the vehicle is shifted to a lower gear than a current driving gear when the vehicle wheel slips; determining whether a TCS operates when the vehicle is downshifted; calculating a new shift pattern gear stage from a preset shift pattern using APS information input from an EMS and transmission output speed information calculated based on a speed of a non-driven wheel when it is determined that the TCS has been activated; and calculating a step difference between the calculated shift pattern gear stage and a current driving stage, an offset gear stage through an offset gear stage determination map based on the calculated step difference and a current APS, and a final slip target stage by adding the calculated offset gear stage to the shift pattern gear stage.

Description

Shift control method and system under rapid acceleration of vehicle in low friction roads

The present invention relates to a shift control method and system for a vehicle running on a low friction road surface, and more particularly, to a vehicle starting performance by mitigating a sudden increase in wheel torque during sudden acceleration while the vehicle is driving on a slippery low friction road surface The present invention relates to a method and system for controlling a shift during rapid acceleration of a vehicle on a low-friction road capable of improving the speed of the vehicle and thus improving the drivability of the vehicle.

In general, when the vehicle is driven on a low-friction road surface covered with snow, rain, ice, etc., there is a possibility that the vehicle may slip and lead to a serious accident while driving. (Electronic Stability Program) is installed and operated.

This ESP prevents the vehicle from sliding to the left or right based on the driving direction by integrating the ABS (anti-lock brake system) and the TCS (Traction Control System) to secure the driving stability of the vehicle. ESP analyzes the state of the steering wheel and compares the direction the driver wants to go with the actual driving direction of the vehicle. It is designed to prevent the vehicle from sliding.

On the other hand, in a situation where the vehicle is driving on a low-friction road surface, if the driver steps on the accelerator more than a certain level to accelerate the vehicle overtaking or make a sudden start, the low friction force of the road surface causes the wheel to slip ( spin) is likely to occur. The slippage generated at this time causes a sharp increase in engine torque (speed), limits engine output by TCS control, and loss of grip of the driving wheel on the road surface, thereby causing instability of the vehicle's behavior.

In the case of a conventional vehicle, regardless of the situation in which the vehicle starts abruptly on a low-friction road surface or when the vehicle starts abruptly on a normal road surface, the vehicle's shift stage control is equipped with a control logic that constantly downshifts. Even when the vehicle starts suddenly at will, the same shift stage control has to be always performed as in the case of a normal road surface.

Due to this, when the vehicle is accelerated rapidly on a low-friction road surface, a downshift lower than the current driving stage is performed according to the set shift control logic. A situation in which wheel slip occurs and the engine RPM rises rapidly occurs. In such a situation, when the TCS is operated and the engine output is limited by the engine control by the TCS, additional output limitation occurs, which greatly reduces the vehicle's starting performance, and thereby causes the vehicle's behavior instability. There was a problem in that the drivability was greatly reduced.

Republic of Korea Patent Registration No. 10-2042825 (2019.11.04)

The present invention has been devised to solve the above problems, and the technical problem to be solved in the present invention is that the driver rapidly steps on the accelerator while the vehicle is driving on a slippery low friction road surface to accelerate or make a sudden start. Instead of the shift stage determined by the control logic of the set shift pattern, shift to the final slip target stage newly corrected and calculated using the current APS information and the output speed of the transmission calculated based on the speed of the non-driven wheel as the shift pattern factors. On a low-friction road that can improve the vehicle's starting performance by mitigating a sharp increase in wheel torque, and thereby stably maintaining the vehicle's behavioral instability to improve the drivability of the vehicle An object of the present invention is to provide a method and system for controlling a shift during rapid acceleration of a vehicle.

According to an aspect of the present invention for solving the above technical problem, there is provided a method for controlling a shift during rapid acceleration of a vehicle on a low-friction road, the method comprising the steps of: (a) determining whether a current vehicle speed of a vehicle is less than or equal to a set value; (b) determining whether the vehicle is in a state of rapid acceleration when the vehicle speed of the vehicle is less than or equal to a set value; (c) determining whether the vehicle wheel slips when the vehicle is in a state of rapid acceleration; (d) determining whether the vehicle is shifted to a lower gear than the current driving stage when slip of the vehicle wheel occurs; (f) determining whether a Traction Control System (TCS) is operated when the vehicle is downshifted; (g) When it is determined that the TCS has been activated, a preset shift pattern using APS (Accel Position Sensor) information input from the EMS (Engine Management System) and the transmission output speed information calculated based on the speed of the non-driven wheel calculating a new shift pattern gear stage from (h) calculating the step difference between the calculated shift pattern gear stage and the current driving stage, and calculating the offset gear stage through the offset gear stage determination map based on the calculated step difference and the current APS, and calculating a final slip target stage by adding the calculated offset gear stage to the shift pattern gear stage.

Preferably, in step (b), it is possible to determine whether the vehicle is rapidly accelerated through the APS information input from the EMS.

In addition, in step (c), the speed of the main driving wheel input from the wheel sensor is compared with the speed of the non-driven wheel, and when the speed of the main driving wheel is greater than the speed of the non-driven wheel, it is determined that the wheel slip has occurred. can

And, in step (g), the engine speed information input from the EMS together with the APS information input from the EMS may be used as an additional factor when calculating the shift pattern gear stage.

In addition, in step (h), when the offset gear stage is calculated, the larger the step difference between the shift pattern gear stage and the current driving stage is, the larger the offset value may be applied in the offset gear stage determination map.

In this case, the offset gear stage calculated from step (h) may be smaller than or equal to the step difference between the shift pattern gear stage and the current driving stage.

In addition, when the offset gear stage is calculated in step (h), a smaller offset value may be applied as the step difference between the shift pattern gear stage and the current driving stage is small and the APS value is small.

On the other hand, according to the present invention, the shift control system during rapid acceleration of a vehicle on a low-friction road. a Transmission Control Unit (TCU) that provides operation information of a Traction Control System (TCS) and controls the transmission of the vehicle so that, when the operation of the TCS is recognized, a downshift is performed according to a preset shift pattern; an Engine Management System (EMS) for providing APS information of the vehicle detected from an Accel Position Sensor (APS) to the TCU; and a wheel sensor that detects the speed of the driving wheel and the speed of the non-driven wheel of the vehicle and provides them to the TCU. Upon recognition, a new shift pattern gear stage is calculated from a preset shift pattern using the APS information input from the EMS and the transmission output speed information calculated based on the speed of the non-driven wheel input from the wheel sensor, An offset gear stage is calculated through an offset gear stage determination map based on the step difference between the calculated shift pattern gear stage and the current driving stage and current APS information, and the calculated offset gear stage is used as a shift pattern gear It is characterized in that the final slip target stage is calculated by summing the stages.

According to the vehicle shift control method and system of the present invention according to the above-described configuration, when the driver accelerates overtaking or makes a sudden start by rapidly stepping on the accelerator over a certain level while the vehicle is driving on a slippery, low-friction road surface, a preset shift Instead of the shift stage determined according to the pattern, a new target shift pattern gear stage to be shifted is recalculated using the output speed of the transmission calculated based on the speed of the non-driven wheel and the current APS information as factors, and the recalculated When it is determined by how many steps the downshift should be made through the step difference between the shift pattern gear stage and the current driving stage, the determined step difference and the current APS are used as factors and an offset gear stage determination map is used to set the offset. ) determining a gear stage, calculating the final slip target stage by adding the determined offset gear stage to the shift pattern gear stage, and controlling the final shift of the vehicle to the calculated final slip target stage. It is possible to prevent excessively downshifting according to a set shift pattern during rapid acceleration, thereby reducing abrupt increase in wheel torque and improving the vehicle's starting performance. Accordingly, there is an effect of improving the drivability of the vehicle by stably maintaining the movement anxiety of the vehicle.

1 is a block diagram showing the main components of a shift control system for a vehicle according to the present invention;
2 is a flowchart sequentially illustrating a method for controlling a shift of a vehicle when a vehicle is rapidly accelerated on a low-friction road according to an embodiment of the present invention.
3 is a block diagram showing main control logic for calculating a sleep target stage according to the present invention.
FIG. 4 is a block diagram showing a control logic for calculating a shift pattern gear stage using the transmission output speed calculated based on the speed of the non-driven wheel in FIG. 3 and APS information as factors;
5 is a diagram showing an offset gear stage is calculated through an offset gear stage determination map using the gear stage difference between the shift pattern gear stage calculated in FIG. 4 and the current driving stage and APS information as factors, and the shift pattern is set to the calculated offset gear stage Block diagram showing the control logic for summing gear stages to yield the final slip target stage.
6 is an exemplary view illustrating an example in which the offset gear step is increased according to the APS size in the offset gear step determination map of FIG. 5 .

Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings so that those of ordinary skill in the art to which the present invention pertains can easily implement them.

However, the present invention may be implemented in several different forms and is not limited to the embodiments described herein. In addition, it should be noted that parts denoted by the same reference numerals throughout the detailed description mean the same components.

Hereinafter, a method and system for controlling a shift during rapid acceleration of a vehicle on a low-friction road according to an embodiment of the present invention will be described in detail with reference to the accompanying drawings.

First, FIG. 1 is a configuration diagram showing the main components of a shift control system for a vehicle according to the present invention.

1 , the shift control system for a vehicle according to the present invention includes a Transmission Control Unit (TCU) 100 for controlling an automatic transmission of the vehicle, a Traction Control System (TCS) 110 for controlling the posture of a vehicle body, and an engine of the vehicle. It is configured to include an EMS (Engine Management System) 120 that controls the vehicle, and a wheel sensor 130 that detects the speed of the front and rear wheels of the vehicle, respectively.

The TCS 110 , which is a vehicle attitude control device, provides on/off information of the TCS 110 to the TCU 100 , and in the TCU 100 , the on/off information provided from the TCS 110 is provided. It is determined whether the current TCS 110 is operating according to the off information.

The TCS 110 operates in a situation in which wheel spin and engine RPM rapidly rise when the driver rapidly steps on the accelerator for overtaking acceleration or a sudden start when the vehicle is driving on a slippery low-friction road surface to limit engine output.

The EMS 120, which is an engine control device, provides the current engine speed (torque) information of the driving vehicle and the current APS information detected from the APS (Accel Position Sensor) to the TCU 100, and also the wheel sensor 130 provides speed information of each of the front wheel and the rear wheel of the vehicle to the TCU 100 .

In the TCU 100 , when it is recognized that the TCS 110 is currently operating, the engine speed and APS information provided from the EMS 120 , and the speed of the main driving wheel and the non-driving wheel provided from the wheel sensor 130 . Using the information, a new shift pattern gear stage (A) is calculated from the set shift pattern using the transmission output speed information recalculated based on the speed of the non-driven wheel, and the calculated shift pattern gear stage (A) information and A final slip target stage C is calculated through a series of control logic shown in FIGS. 2 to 6 to be described later using the APS information, and the shift is controlled to be performed to the calculated slip target stage.

In general, when a driver's acceleration request is recognized in a vehicle traveling on a low-friction road surface, the TCU controls a downshift lower than the current driving stage according to a preset shift pattern. However, the existing shift pattern logic by the TCU is designed to always perform a downshift lower than the current driving stage in a situation where the vehicle starts abruptly without distinction between a low friction road surface or a normal road surface, so the vehicle accelerates rapidly on a slippery low friction road surface. Even in the case of a normal road surface, shift control is inevitably performed according to the same preset shift pattern as in the normal road surface. On the other hand, the engine RPM rises rapidly, and if the engine output limit by the TCS is made in this state, an additional engine output limit occurs and the vehicle's starting performance may be greatly reduced, which may cause unstable behavior of the vehicle and thus the drivability. can drop

In the present invention, when it is recognized that the TCS 110 has been operated after the wheel slip of the vehicle has occurred, in order to improve the starting performance degradation of the vehicle caused by excessive shifting during rapid acceleration of the vehicle on a low-friction road surface, the EMS 120 A new transmission output speed is calculated based on the speed of the non-driven wheel using the input APS information and the wheel speed information input from the wheel sensor 130, and a preset value is set using the transmission output speed information and the APS information as factors. After calculating the new shift pattern gear stage (A) from the shift pattern, the step difference between the calculated shift pattern gear stage (A) and the current driving stage is calculated, and the offset using the calculated step difference and the current APS information as a factor After calculating the offset gear stage (B) through the gear stage determination map (M), the calculated offset gear stage (B) is added to the shift pattern gear stage (A) to calculate the final slip target stage (C), , by controlling the shift to the calculated slip target stage, it is possible to prevent excessive shifting even when the vehicle is rapidly accelerated on a low-friction road surface, thereby improving the vehicle's starting performance.

Although the present invention has been described using a vehicle in which the front wheel (front wheel) is a driving wheel and the rear wheel (rear wheel) is a non-driven wheel as an embodiment, the vehicle in which the rear wheel is a driving wheel and the front wheel is a non-driven wheel or a 4WD vehicle is switched to 2WD mode Of course, the same can be applied even when the operation is performed.

2 is a flowchart sequentially showing a method for controlling a shift of a vehicle during rapid acceleration of a vehicle on a low friction road according to an embodiment of the present invention, and FIG. 3 is a block showing main control logic for calculating a slip target stage according to the present invention It is a diagram. 4 is a block diagram showing a control logic for calculating a shift pattern gear stage using the transmission output speed and APS information calculated based on the speed of the non-driven wheel in FIG. 3 as factors, and FIG. 5 is calculated in FIG. The offset gear stage is calculated through the offset gear stage determination map using the gear stage difference between the shift pattern gear stage and the current driving stage and APS information as factors, and the shift pattern gear stage is added to the calculated offset gear stage to make the final slip It is a block diagram showing the control logic that produces the target stage. In addition, FIG. 6 shows an example in which the offset gear step is increased according to the APS size in the offset gear step determination map of FIG. 5 .

2 to 6 , when the vehicle travels on a slippery, low-friction road surface covered with snow, rain, or ice, the TCU 100 receives a front wheel and a rear wheel from the wheel sensor 130 of the vehicle. wheel) to determine whether the current vehicle speed of the vehicle is less than or equal to a set value (eg, 80 km/h) (S210).

Here, in the step S210, the current vehicle speed of the vehicle is set to the medium or low vehicle speed in step S210 because the possibility of wheel slip on the road surface is relatively high when sudden acceleration occurs in a situation where the vehicle is traveling at medium and low vehicle speeds on a low friction road surface. It can be determined whether the speed is 80 km/h or less.

And, when it is determined from step S210 that the current vehicle speed is in a low-speed driving state below the set value, APS information reflecting the driver's acceleration request is provided from the EMS 120 to determine whether the vehicle is currently in a rapid acceleration state Determine. (S220)

At this time, if the APS value input from the EMS 120 is greater than or equal to a set value (eg, 50%), it is determined that a request for rapid acceleration of the vehicle has been made by the driver, and if the APS value is less than or equal to the set value, shift control is terminated.

Here, since the amount of change in APS is an important factor in addition to the absolute value of APS when judging the rapid acceleration of the vehicle, it is preferable that the rapid acceleration of the vehicle is determined if both conditions of APS > 50% and APS change > 50% are simultaneously satisfied. may be

Subsequently, when it is determined from step S220 that the vehicle is currently in a rapid acceleration state, whether a slip has occurred in the current vehicle wheel through speed information of the main driving wheel and the non-driving wheel provided from the wheel sensor 130 . is determined. (S230)

In this case, by comparing the speed of the main driving wheel input from the wheel sensor 130 and the speed of the non-driving wheel, if the speed of the main driving wheel is greater than the speed of the non-driving wheel, it is determined that slip has occurred in the vehicle wheel And, when the speed of the main driving wheel is less than or equal to the speed of the non-driving wheel, it is determined that the vehicle wheel does not slip.

And, if it is determined from step S230 that slip has occurred in the current vehicle wheel, it is determined whether the vehicle is shifted to a lower level than the current driving level according to the shift pattern logic set in the TCU 100 (S240).

Subsequently, when it is determined from step S240 that the downshift of the vehicle is engaged, it is determined whether the TCS 110 of the vehicle is currently operating using ON/OFF information of the TCS input from the TCS 110 . It is determined whether or not (S250)

On the other hand, when it is recognized that the TCS 110 is currently operating from the step S250, the TCU 100 transmits the APS information input from the EMS 120 and the transmission output speed information newly calculated based on the speed of the non-driven wheel. A new shift pattern gear stage (A) is calculated from the preset shift pattern by using (S260).

In this case, when the shift pattern gear stage A is calculated, engine speed information may be additionally reflected together with the APS information input from the EMS 120 . Here, since the speed of the engine means the output speed of the transmission, the engine speed information (RPM) input from the EMS 120 may be used when calculating the output speed of the transmission.

That is, since the output stage of the transmission is physically connected to the driving wheel, the rotational speed (RPM) on the output side of the transmission can be calculated by considering the rotational speed of the driving wheel (KPH -> RPM unit conversion) and the final deceleration ratio.

In addition, the transmission output speed calculation is generally calculated based on the speed of the vehicle's main drive wheel. Since it is the same as the speed of the driving wheel and does not match the actual driving speed of the vehicle, in the present invention, instead of calculating the output speed of the transmission based on the speed of the main driving wheel, the output of the transmission is based on the speed of the non-driven wheel. speed is recalculated. Then, using the recalculated output speed information of the transmission and the current APS information provided from the EMS 120 as factors, a new shift pattern gear stage A is recalculated from the preset shift pattern (FIG. 4). Reference)

On the other hand, when the new shift pattern gear stage (A) dl is calculated from the step S260, the TCU 100 calculates the difference between the shift pattern gear stage (A) recalculated from the step S260 and the current driving stage of the vehicle as shown in FIG. 5 . After calculating how many gear steps should be downshifted from the current driving stage by calculation, the calculated gear step and the current APS value are used as factors, and the offset gear as shown in FIG. 6 programmed in the TCU 100 A new offset gear stage (B) is determined through the stage determination map (M), and the determined offset gear stage (B) is added to the shift pattern gear stage (A) to achieve the final slip shift target stage (C) ) is calculated. (S270)

When the offset gear stage (B) is calculated using the offset gear stage determination map (M), a larger offset value is applied as the gear difference between the shift pattern gear stage (A) and the current driving stage is greater, and the shift pattern gear stage The smaller the gear step difference between (A) and the current driving stage is and the smaller the APS value is, the smaller the offset value may be applied to calculate the offset gear stage (B).

Here, the offset gear stage determination map (M) is an offset gear stage determination map using the gear stage difference between the shift pattern gear stage (A) and the current driving stage and the APS as an axis, and the larger the gear stage difference and the APS value, the greater the offset Although the (Offset) value increases, it cannot be greater than the gear step. Accordingly, the offset gear stage B calculated from the step S270 may be less than or equal to the gear difference difference between the shift pattern gear stage A and the current driving stage.

As an example of the above control process, when a sudden acceleration of APS=100% is made by the driver's will to accelerate in a situation in which the vehicle is driving at 70km/h, 8-speed, and APS=10%, the preset shift 8->3 shift is made in which the target shift stage is changed to 3rd gear according to the pattern, but in the present invention, when the TCS is operated due to wheel slip of the driving wheel during the 8->3 shift, the vehicle speed of the non-driven wheel It is a method of correcting the slip target stage to the final slip shift target stage (5th gear) by adding the pattern gear stage (3rd gear) calculated based on the It is capable of performing 8->5 shifts.

When the calculation of the final slip target stage C is completed through this series of processes, the TCU 100 controls the shift to the calculated slip target stage C, so that the driver's acceleration request on a low-friction road By preventing excessive downshifting even when rapid acceleration is generated by the

In the above, preferred embodiments of the present invention have been described, but the scope of the present invention is not limited to these specific embodiments, and those skilled in the art may appropriately change within the scope described in the claims of the present invention. this will be possible

100: TCU 110: TCS
120: EMS 130: wheel sensor

Claims (14)

(a) determining whether the current vehicle speed of the vehicle is less than or equal to a set value;
(b) determining whether the vehicle is in a state of rapid acceleration when the vehicle speed of the vehicle is less than or equal to a set value;
(c) determining whether the vehicle wheel slips when the vehicle is in a state of rapid acceleration;
(d) determining whether the vehicle is shifted to a lower gear than the current driving stage when slip of the vehicle wheel occurs;
(f) determining whether a Traction Control System (TCS) is operated when the vehicle is downshifted;
(g) If it is determined that the TCS has been activated, a preset shift pattern using APS (Accel Position Sensor) information input from the EMS (Engine Management System) and the transmission output speed information calculated based on the speed of the non-driven wheel calculating a new shift pattern gear stage from
(h) calculating the step difference between the calculated shift pattern gear stage and the current driving stage, and calculating the offset gear stage through the offset gear stage determination map based on the calculated step difference and the current APS, calculating a final slip target stage by adding the calculated offset gear stage to the shift pattern gear stage; A shift control method during rapid vehicle acceleration on a low-friction road comprising a.
[2] The method of claim 1, wherein in step (b), whether the vehicle is rapidly accelerated or not is determined through the APS information input from the EMS.
According to claim 1, wherein in step (c), the speed of the main driving wheel input from the wheel sensor and the speed of the non-driven wheel are compared, and when the speed of the main driving wheel is greater than the speed of the non-driven wheel, the wheel slip occurs. A shift control method during rapid acceleration of a vehicle on a low-friction road, characterized in that it is determined that the
The vehicle grade on a low friction road according to claim 1, wherein the engine speed information input from the EMS together with the APS information input from the EMS is used as an additional factor when calculating the shift pattern gear stage in the step (g). How to control shifting when accelerating.
The low-friction road according to claim 1, wherein when the offset gear stage is calculated in the step (h), the larger the step difference between the shift pattern gear stage and the current driving stage is, the larger the offset value is set in the offset gear stage determination map. Shift control method during rapid vehicle acceleration in
The method of claim 1 , wherein the offset gear stage calculated in step (h) is smaller than or equal to a step difference between the shift pattern gear stage and the current driving stage.
According to claim 1, wherein in the step (h), the offset gear stage is set to a smaller offset value as the step difference between the shift pattern gear stage and the current driving stage is small and the APS value is small. How to control shifting when accelerating.
a TCU (Transmission Control Unit) that provides operation information of a Traction Control System (TCS) and controls the transmission of the vehicle so that when the operation of the TCS is recognized, a downshift is performed according to a preset shift pattern;
EMS (Engine Management System) for providing APS information of the vehicle detected from APS (Accel Position Sensor) to the TCU;
A wheel sensor that detects the speed of the driving wheel and the speed of the non-driven wheel of the vehicle, respectively, and provides it to the TCU; includes;
When it is recognized that the TCS has been activated after wheel slip occurs during rapid acceleration of the vehicle, the TCU is a transmission calculated based on the APS information input from the EMS and the speed of the non-driven wheel input from the wheel sensor After calculating a new shift pattern gear stage from a preset shift pattern using the output speed information, an offset gear stage determination map is created based on the step difference between the calculated shift pattern gear stage and the current driving stage and the current APS information. A shift control system during rapid acceleration of a vehicle on a low friction road, characterized in that calculating an offset gear stage through the calculation, and adding the calculated offset gear stage to a shift pattern gear stage to calculate a final slip target stage.
The system according to claim 8, wherein the TCU determines whether the vehicle is rapidly accelerated through APS information input from the EMS.
The method of claim 8, wherein the TCU determines whether the vehicle wheel slips by comparing the speed of the main driving wheel input from the wheel sensor and the speed of the non-driving wheel so that the speed of the main driving wheel is the speed of the non-driving wheel. A shift control system for sudden acceleration of a vehicle on a low friction road, characterized in that it is determined that wheel slip has occurred if it is greater.
The vehicle on a low friction road according to claim 8, wherein, when the TCU re-releases the shift pattern gear stage, the engine speed information of the vehicle input from the EMS is used as an additional factor together with the APS information input from the EMS. Shift control system during rapid acceleration.
The vehicle on a low friction road according to claim 8, wherein the larger the step difference between the shift pattern gear stage and the current driving stage when the TCU calculates the offset gear stage, the larger the offset value is set in the offset gear stage determination map. Shift control system during rapid acceleration.
The shift control system according to claim 8, wherein the offset gear stage calculated by the TCU is less than or equal to a step difference between the shift pattern gear stage and the current driving stage.
The vehicle rapid acceleration on a low friction road according to claim 8, wherein the offset gear stage calculated by the TCU is set to a smaller offset value as the step difference between the shift pattern gear stage and the current driving stage is small and the APS value is small. shift control system.

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