CN111559374A - A constant speed control method on large ramps based on cruise control system - Google Patents

Abstract

The invention discloses a constant speed control method for a large slope based on a constant speed cruise system. The method comprises the steps of detecting the current vehicle speed and the road gradient in real time under the constant-speed cruising condition, if the vehicle speed exceeds an error allowable value and lasts for a certain time and the gradient exceeds a set gradient, cooperatively adopting a cooperative working mode to work to maintain the vehicle speed to be constant, and otherwise, adopting a normal working mode to maintain the vehicle speed to be constant. The method optimizes the control flow of the execution end of the constant-speed cruise system to the vehicle speed, creatively introduces ESC intervention to control the vehicle speed in a ramp scene, and can avoid the problem that the constant-speed cruise system exceeds the set vehicle speed in the ramp or other extreme scenes; the risk that the vehicle cannot keep constant speed or even exceed the speed limit on a large slope is avoided, and the safety of a driver is ensured.

Description

A constant speed control method on large ramps based on cruise control system

technical field

The invention belongs to the technical field of automobile braking control, and in particular relates to a method for controlling a constant vehicle speed on a large slope based on a cruise control system.

Background technique

At present, the relevant cruise control system only considers the support of the engine and torque module in product development; taking a well-known automobile company as an example, among the products that support cruise control, the vehicle speed cannot be kept constant on more than 20% of the slopes. The typical performance is that the speed of the vehicle increases significantly after entering the ramp, and it cannot be maintained or restored to the set speed for a long time; on a ramp of more than 30%, the vehicle speed will continue to increase due to the fact that the weight of the vehicle itself is greater than the negative torque limit of the engine, which is dangerous.

The traditional single torque and throttle control of the existing cruise control system, as well as the negative torque generated solely by the reverse drag of the engine, can no longer meet the speed control requirements of the cruise control system on slopes.

SUMMARY OF THE INVENTION

The purpose of the present invention is to solve the above-mentioned shortcomings of the background technology, and to provide a constant speed control method on a large slope based on a cruise control system.

The technical scheme adopted in the present invention is: a constant speed control method on a large slope based on a cruise control system at a constant speed, under the condition of cruise control at a constant speed, the current vehicle speed and road gradient are detected in real time. When the gradient exceeds the set gradient, the cooperative works in the cooperative working mode to keep the vehicle speed constant; otherwise, it adopts the normal working mode to keep the vehicle speed constant.

Further, in the normal working mode, the EMS engine control unit independently distributes the brake pressure to achieve constant control of the vehicle speed.

Further, the cooperative working mode is that the EMS engine control unit and the ESC brake auxiliary unit jointly complete the distribution of the brake pressure to realize the constant control of the vehicle speed.

Further, the allowable value of the error is ±2km/h of the set vehicle speed.

Further, in the cooperative work mode, the cruise control controller confirms that the negative torque capability of the EMS engine control unit has reached the maximum and cannot maintain a constant vehicle speed, then the cruise control controller sends a maximum negative torque request until it exits the cooperative work mode. At this time, the ESC brake assist unit adopts a positive deceleration response mode to maintain a constant vehicle speed.

Further, the process that the ESC braking assistance unit adopts the positive deceleration response mode to maintain a constant vehicle speed is: when it is detected that the gravity component on the slope is greater than the required acceleration request, the ESC braking assistance unit generates a positive acceleration response interval, Calculate the maximum gravity component acceleration of the vehicle, when the cruise control controller requests the controller to request positive acceleration, the ESC brake assist unit divides the required brake pressure to complete the vehicle speed control.

The present invention optimizes the control process of the speed control system for the execution end of the cruise control system, and creatively introduces the ESC to intervene in the control of the vehicle speed in the ramp scene, which can prevent the cruise control system from cruising at a constant speed on a ramp or in other extreme scenarios exceeding the set vehicle speed. It eliminates the risk that the vehicle cannot maintain a constant speed or even exceeds the speed limit when it is sent on a large ramp, and ensures the safety of the driver; the invention expands the controllable and applicable scope of the cruise control at a fixed speed, and provides a new functional selling point for enterprise products. For the safety of our customers. The invention is simple and practical, suitable for all vehicle types, can interact with various types of ESC-EMS (VCU), and operates in a modularized manner.

Description of drawings

FIG. 1 is a schematic diagram of a control flow of the present invention.

FIG. 2 is an effect diagram of the present invention in the scene of entering a 20-degree ramp.

FIG. 3 is an effect diagram of the present invention in the scene of entering a 30-degree ramp.

Detailed ways

The specific embodiments of the present invention will be further described below with reference to the accompanying drawings. It should be noted here that the descriptions of these embodiments are used to help the understanding of the present invention, but do not constitute a limitation of the present invention. In addition, the technical features involved in the various embodiments of the present invention described below can be combined with each other as long as there is no conflict with each other.

The present invention provides a constant speed control method on a large slope based on a cruise control system. The control system corresponding to the method includes an EMS engine control unit (VCU motor vehicle controller), a cruise control controller (which can be combined with other functions) Built in domain controller), ESC brake assist unit and vehicle CAN bus;

The EMS engine control unit (VCU motor vehicle controller) is used to respond to a normal torque request and satisfy the basic acceleration and deceleration, vehicle speed maintenance, and power output distribution of the cruise control system.

The vehicle CAN bus is used to provide the point dynamic gradient signal and the real-time vehicle speed signal to the controller.

The ESC brake assist unit is used to generate a slight brake to ensure effective control of the vehicle speed when the single torque and throttle control, and the negative torque generated solely by the reverse drag of the engine cannot meet the vehicle speed control requirements.

The cruise control controller will comprehensively distribute the output torque and deceleration request, output a relatively suitable deceleration request under various conditions, and control the vehicle speed on normal roads and slopes according to the vehicle speed, dynamic gradient and current vehicle speed. constant, until the vehicle speed is maintained in the normal working range of ±2km/h allowed by the error; that is, the cruise control system and the method of constant speed on large slopes of the present invention are realized, and then the cruise control controller continues to control the coordinated torque and braking reduction. speed relationship.

The unique positive deceleration response mode of the present invention is specially developed for the ESC brake assist unit with this function. When it is detected that the gravity component on the slope is greater than the required acceleration request (for example, on a standard 30° slope, the actual calibrated vehicle gravity acceleration component of the D53EV model used to develop this function is 3.2m/s ² , which is greater than the system needs to accelerate 2m/s ² , and 0m/s ² to ensure the constant speed of the vehicle), generate a reliable positive acceleration response interval, and calculate the maximum gravity component acceleration predicted by the vehicle. When the cruise control controller requests the controller to request positive acceleration , the ESC brake assist unit can distribute the brake pressure to complete the vehicle speed control just like the ESC control unit that normally only supports the deceleration request.

The special cruise control controller is used for balancing the power torque output and braking control on large slopes. The unique control method of the present invention is adopted. When the coordinated action of multiple sensors is required, the unique three-layer feedback adjustment mode ensures the speed of the vehicle. constant.

In the above technical solution, when the cruise control controller performs a normal speed control function and receives a dynamic gradient signal exceeding the threshold value, it enters the unique cooperative control mode of the present invention when all the following conditions are met:

Condition 1: The dynamic gradient (that is, the road gradient) exceeds the specified threshold; Condition 2: The cruise control function is activated; Condition 3: The vehicle speed exceeds the allowable error of 2km/h for 3s; Condition 4: The basic function of ESC is not enabled and there is no fault;

In the above-mentioned collaborative scheme of the invention, if it is confirmed that the conditions are satisfied and the collaborative working mode is entered to ensure that the vehicle maintains a constant vehicle speed, the cruise control controller first confirms that the negative torque capability of the EMS engine control unit (VCU motor vehicle controller) has reached the maximum and cannot be Keep the vehicle speed constant; then the cruise control controller sends a maximum negative torque request to ensure that the torque braking potential is exhausted, until it exits the cooperative work mode, and finally, enters the function of the present invention. The speed response mode keeps the vehicle speed constant; the discrimination mode can effectively balance the relationship between braking and power on large slopes.

As shown in Figure 1, the method for constant vehicle speed on a large slope based on the above system specifically includes the following steps:

Step 1: The vehicle CAN bus is used to provide dynamic gradient signals and real-time vehicle speed signals to the cruise control controller;

Step 2: Use 3-fold feedback cruise control mode (that is, normal working mode) on flat ground or small slopes to ensure the stability of the cruise system only under torque control.

Step 3: When the cruise control controller detects that the dynamic gradient exceeds the limit and the vehicle speed cannot be controlled, and other conditions are met, the cooperative working mode is turned on:

Step 4: The ESC braking auxiliary unit then enters the original positive deceleration response mode of the present invention.

Step 5: The cruise control controller is used to balance the power torque output and braking control on large slopes. The unique control method of the present invention is adopted. When multi-sensor cooperative action is required, the unique three-layer feedback adjustment mode ensures the constant speed of the vehicle. .

As shown in Figure 2 and Figure 3, it is the effect diagram of the vehicle speed control realized by the method of the present invention. It can be clearly seen from the figure that when the slope exceeds a certain value, the torque output of the existing single mode cannot control the vehicle speed to be constant. The invented method can maintain the vehicle speed within the error range, thereby effectively improving driving safety.

The above are only specific embodiments of the present invention, but the protection scope of the present invention is not limited thereto. Any changes or substitutions that can be easily thought of by those skilled in the art within the technical scope disclosed by the present invention should be covered. within the protection scope of the present invention. Contents not described in detail in this specification belong to the prior art known to those skilled in the art.

Claims (6)

1. a large ramp constant vehicle speed control method based on cruise control system, is characterized in that: under cruise control condition, real-time detection of current vehicle speed and road gradient, if the vehicle speed exceeds the error allowable value and continues for a certain time and the gradient exceeds If the slope is set, the cooperative works in the cooperative working mode to keep the vehicle speed constant; otherwise, it adopts the normal working mode to keep the vehicle speed constant. 2 . The method for constant vehicle speed control on large slopes based on cruise control system according to claim 1 , wherein the normal working mode is that the EMS engine control unit independently distributes the braking pressure to realize the constant control of the vehicle speed. 3 . 3. The method for controlling a constant vehicle speed on a large slope based on a cruise control system according to claim 1, wherein the cooperative working mode is that the EMS engine control unit and the ESC brake assist unit jointly complete the distribution of the brake pressure to achieve Constant control of vehicle speed. 4 . The constant speed control method on a large slope based on a cruise control system according to claim 1 , wherein the allowable error value is ±2km/h of the set speed. 5 . 5. The constant speed control method for large slopes based on cruise control system according to claim 1, characterized in that: in the cooperative operation mode, the cruise control controller confirms that the negative torque capability of the EMS engine control unit has reached the maximum And the vehicle speed cannot be maintained constant, the cruise control controller will send a maximum negative torque request until it exits the cooperative working mode. At this time, the ESC brake assist unit adopts the positive deceleration response mode to maintain the vehicle speed constant. 6. The constant speed control method on a large slope based on a cruise control system according to claim 5, characterized in that: the process of the ESC brake assist unit adopting a positive deceleration response mode to maintain a constant vehicle speed is: when monitoring When the gravity component on the slope is greater than the required acceleration request, the ESC brake assist unit generates a positive acceleration response interval and calculates the maximum gravity component acceleration of the vehicle. When the cruise control controller requests the controller to request positive acceleration, the ESC brake assist unit The unit divides the demanded distribution brake pressure to complete the vehicle speed control.

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