Cross-country cruise control method based on dual-motor PI control

Abstract

The invention provides an off-road cruise control method based on dual-motor PI control, which comprises the following steps: S1, when a vehicle control unit recognizes that a vehicle enters an off-road cruise mode, recognizing a current target gear; s2, the vehicle control unit calculates the target vehicle speed according to the target gear; s3, the vehicle control unit calculates the difference value between the target vehicle speed and the actual vehicle speed, and an initial target torque is calculated according to the difference value through a PI control algorithm; and S4, the vehicle control unit judges whether the initial target torque is distributed to a front motor and a rear motor of the vehicle or not according to the state of the vehicle. According to the invention, the vehicle speed of the vehicle during cross-country cruise can be controlled in real time, so that the vehicle speed is relatively stable.

Description

Technical Field

[0001] The invention belongs to the technical field of automobile control, and in particular relates to an off-road cruise control method based on dual-motor PI control. Background Art

[0002] Modern cars need to face complex road conditions when driving in off-road mode, such as mountains, mud, rocks, sand, etc. Therefore, driving in off-road conditions requires certain skills, especially for some novices. The complex terrain in off-road mode is very difficult to drive, and it is easy to have unstable speed. Therefore, how to design an off-road cruise control method based on dual-motor PI control to achieve the control of the vehicle speed in off-road cruise mode so that the vehicle speed is relatively stable has become a technical problem that technicians in this field need to solve urgently. Summary of the invention

[0003] The purpose of the present invention is to provide an off-road cruise control method based on dual-motor PI control to solve the above technical problems in the prior art.

[0004] To achieve the above object, the present invention provides the following technical solutions:

[0005] An off-road cruise control method based on dual-motor PI control comprises the following steps:

[0006] Step S1: When the vehicle controller recognizes that the vehicle enters the off-road cruise mode, the current target gear is identified;

[0007] Step S2, the vehicle controller calculates the target vehicle speed according to the target gear position;

[0008] Step S3, the vehicle controller calculates the difference between the target vehicle speed and the actual vehicle speed, and calculates the initial target torque based on the difference using the PI control algorithm;

[0009] Step S4: The vehicle controller determines whether to distribute the initial target torque to the front motor and the rear motor of the vehicle according to the vehicle state;

[0010] The vehicle status includes whether the vehicle is in D gear, whether it is in parking state, whether the driver steps on the brake, and whether the driver steps on the accelerator;

[0011] If the vehicle is in the D gear, not in the parking state, and the driver does not step on the brake or the accelerator, the initial target torque is distributed to the front motor and the rear motor in a certain ratio;

[0012] If the vehicle is not in D gear or in parking state or the driver steps on the brake, the initial target torque is not distributed to the front motor and the rear motor.

[0013] Preferably, step S4 also includes: if the vehicle controller receives a signal that the driver has stepped on the accelerator, the throttle torque is calculated according to the throttle size, and the throttle torque is compared with the initial target torque, and whether the driver should take over is determined according to the comparison result.

[0014] Preferably, if the throttle torque is greater than the initial target torque, the throttle torque is output and the vehicle is taken over by the driver. After the driver releases the accelerator, the vehicle controller looks up the table according to the current actual vehicle speed to obtain the corresponding target negative torque, and distributes the target negative torque to the rear motor to reduce the vehicle speed to near the target speed, and then uses the PI control algorithm to calculate the current initial target torque and then distribute it to the front motor and the rear motor.

[0015] Preferably, if the throttle torque is not greater than the initial target torque, the throttle torque is not responded to, the vehicle does not need the driver to take over, and the initial target torque is distributed to the front motor and the rear motor.

[0016] Preferably, when the initial target torque is distributed to the front motor and the rear motor of the vehicle, if the vehicle controller receives a steering signal from the vehicle, it obtains the corresponding steering compensation torque by looking up the table according to the current steering angle during steering, and then superimposes the steering compensation torque with the initial target torque before outputting it.

[0017] Preferably, when the initial target torque is distributed to the front motor and the rear motor of the vehicle, if the vehicle controller receives a slope signal, it obtains the corresponding slope compensation torque according to the current slope lookup table, and then superimposes the slope compensation torque with the initial target torque and outputs it.

[0018] Preferably, when the initial target torque is distributed to the front motor and the rear motor of the vehicle, if the vehicle controller receives the steering signal and the slope signal of the vehicle at the same time, the steering compensation torque and the slope compensation torque are superimposed on the initial target torque and then output.

[0019] Preferably, the above-mentioned certain ratio is 1:1.

[0020] The beneficial effects of the present invention are:

[0021] The off-road cruise control method based on dual-motor PI control of the present invention can control the vehicle speed in real time during off-road cruising, so that the vehicle speed is relatively stable, avoiding the situation where the vehicle speed fluctuates when driving on complex roads, ensuring the stable driving of the vehicle and reducing the requirements on the driver's driving skills. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the following will briefly introduce the drawings required for use in the embodiments, and further describe the specific embodiments of the present invention in detail in conjunction with the drawings, wherein

[0023] Figure 1 A flow chart of an off-road cruise control method based on dual-motor PI control provided by an embodiment of the present invention. DETAILED DESCRIPTION

[0024] Various exemplary embodiments of the present invention will now be described in detail with reference to the accompanying drawings. It should be noted that the relative arrangement of components and steps, numerical expressions and numerical values ​​set forth in these embodiments do not limit the scope of the present invention unless otherwise specifically stated.

[0025] The following description of at least one exemplary embodiment is merely illustrative in nature and is in no way intended to limit the invention, its application, or uses.

[0026] Technologies, methods, and equipment known to ordinary technicians in the relevant art may not be discussed in detail, but where appropriate, the technologies, methods, and equipment should be considered as part of the specification.

[0027] In all examples shown and discussed herein, any specific values ​​should be interpreted as merely exemplary and not limiting. Therefore, other examples of the exemplary embodiments may have different values.

[0028] like Figure 1 As shown, an embodiment of the present invention provides an off-road cruise control method based on dual-motor PI control, which includes the following steps:

[0029] Step S1: When the vehicle controller recognizes that the vehicle enters the off-road cruise mode, the current target gear is identified;

[0030] Step S2, the vehicle controller calculates the target vehicle speed according to the target gear position;

[0031] Step S3, the vehicle controller calculates the difference between the target vehicle speed and the actual vehicle speed, and calculates the initial target torque based on the difference using the PI control algorithm;

[0032] Step S4: The vehicle controller determines whether to distribute the initial target torque to the front motor and the rear motor of the vehicle according to the vehicle state;

[0033] The vehicle status includes whether the vehicle is in D gear, whether it is in parking state, whether the driver steps on the brake, and whether the driver steps on the accelerator;

[0034] If the vehicle is in the D gear, not in the parking state, and the driver does not step on the brake or the accelerator, the initial target torque is distributed to the front motor and the rear motor in a certain ratio;

[0035] If the vehicle is not in D gear or in parking state or the driver steps on the brake, the initial target torque is not distributed to the front motor and the rear motor. At this time, the initial target torque can also be set to zero.

[0036] The off-road cruise control method based on dual-motor PI control provided by the embodiment of the present invention can control the vehicle speed in real time during off-road cruising, so that the vehicle speed is relatively stable, avoiding the situation where the vehicle speed fluctuates when driving on complex roads, thereby ensuring the stable driving of the vehicle; at the same time, it also reduces the requirements on the driver's driving skills.

[0037] Furthermore, step S4 also includes: if the vehicle controller receives a signal that the driver has stepped on the accelerator, the accelerator torque is calculated according to the accelerator size, and the accelerator torque is compared with the initial target torque, and whether the driver should take over is determined according to the comparison result, specifically:

[0038] If the throttle torque is greater than the initial target torque, the throttle torque is output and the vehicle is taken over by the driver. After the driver releases the throttle, the vehicle controller looks up the table according to the current actual vehicle speed to obtain the corresponding target negative torque, and distributes the target negative torque to the rear motor to reduce the actual vehicle speed to near the target speed, such as within 3km / h of the target speed. Then, the PI control algorithm is used to calculate the current initial target torque, and then it is distributed to the front motor and the rear motor.

[0039] If the throttle torque is not greater than the initial target torque, the throttle torque will not be responded to, and the vehicle does not need the driver to take over, and the initial target torque will be distributed to the front motor and the rear motor.

[0040] Specifically, if the difference between the target speed and the actual speed is recorded as Δ, then Δ = target speed minus actual speed, and the value of Δ can be positive or negative. At this time, the specific method for calculating the initial target torque using the PI control algorithm based on the above difference is: according to the product of the value of Δ and the value of the linear proportional parameter P, the torque value under the control of the P parameter at the current moment is obtained; and according to the product of the value of Δ and the value of the differential parameter I, the torque value under the control of the I parameter at the current moment is obtained. The torque value needs to be superimposed with the sampling period to eliminate the steady-state error under the control of the P parameter; then the above torque value calculated under the P parameter and the above torque value calculated under the I parameter are superimposed to obtain the initial target torque.

[0041] Further, in step S4, when the initial target torque is distributed to the front motor and the rear motor of the vehicle:

[0042] If the vehicle controller receives a steering signal from the vehicle, it will look up the table according to the current steering angle to obtain the corresponding steering compensation torque, and then superimpose the steering compensation torque with the initial target torque before outputting it. At this time, the superimposed torque can be distributed to the front motor and the rear motor according to a certain ratio;

[0043] If the vehicle controller receives a slope signal, it will look up the table according to the current slope to obtain the corresponding slope compensation torque, superimpose the slope compensation torque with the initial target torque and then output it. At this time, the superimposed torque can be distributed to the front motor and the rear motor according to a certain ratio;

[0044] If the vehicle controller receives the vehicle's steering signal and slope signal at the same time, the steering compensation torque and slope compensation torque are superimposed on the initial target torque and then output. At this time, the superimposed torque can be distributed to the front motor and the rear motor according to a certain ratio.

[0045] It is understandable that the above-mentioned relevant data obtained by table lookup can be obtained in advance through experiments, and then the corresponding tables can be made, such as: the vehicle speed-target negative torque correspondence table can be obtained in advance through experiments, and the target negative torque is positively correlated with the vehicle speed; the steering angle-steering compensation torque correspondence table can be obtained in advance through experiments, and the steering compensation torque is positively correlated with the steering angle; the slope-slope compensation torque correspondence table can be obtained in advance through experiments, and the slope compensation torque is positively correlated with the slope. When the vehicle is climbing a slope, the slope is positive, and the corresponding slope compensation torque at this time is also positive; when the vehicle is going downhill, the slope is negative, and the corresponding slope compensation torque at this time is also negative.

[0046] Specifically, the above-mentioned certain ratio is 1: 1. It can be understood that in a specific application, the specific value of the ratio can be flexibly set as needed.

[0047] According to the present invention, after the driver selects the off-road cruise function and the target gear through the control panel on the vehicle, the vehicle controller (VCU) can calculate the target vehicle speed according to the target gear, and then perform PI calculation according to the difference between the target vehicle speed and the actual vehicle speed to obtain the current initial target torque, and then distribute the initial target torque to the front and rear motors in a certain proportion to drive the vehicle; and can perform real-time correction on the initial target torque according to the real-time difference between the target vehicle speed and the actual vehicle speed to ensure that the vehicle speed is relatively stable; and when a steering signal and a slope signal are received, the steering compensation torque and the slope compensation torque are superimposed on the current initial target torque calculated by PI and then distributed to the front and rear motors.

[0048] Specifically, the VCU can obtain the vehicle's steering signal and steering angle information through the vehicle's airbag controller (SRS), and obtain the slope signal and the slope information of the road surface through the vehicle's inertial measurement unit (IMU).

[0049] When the vehicle is climbing a slope, the resistance of the whole vehicle suddenly increases. At this time, the control method of the present invention can provide a larger slope torque compensation for the front motor and the rear motor to prevent the vehicle speed from decreasing too little or even sliding down the slope; when the vehicle is going downhill, the resistance suddenly decreases. At this time, the present invention can provide negative torque for the two motors to drag and prevent the vehicle speed from being too high; when turning, the resistance of the whole vehicle increases. At this time, the present invention can provide a corresponding amount of torque compensation to the two motors according to the size of the turning angle to prevent the vehicle speed from decreasing.

[0050] In the present invention, when the actual vehicle speed is higher than the target vehicle speed after the throttle torque intervenes, the driver takes over the driving of the vehicle. After the driver releases the throttle, the rear motor drags according to the target negative torque to reduce the vehicle speed. At this time, this process can be used to generate electricity, converting excess kinetic energy into electrical energy to increase the endurance of the vehicle. The present invention can especially achieve the control of the vehicle speed of a hybrid four-wheel drive pickup during off-road cruising, achieve a stable forward speed of the vehicle, and prevent the problem of too high or too low speed under complex road conditions. The present invention can enable the vehicle to maintain a stable speed on a complex road in off-road cruising mode, and can provide slope torque compensation during uphill and downhill processes, and provide steering torque compensation during steering, so that the vehicle can maintain a stable speed.

[0051] Although some specific embodiments of the present invention have been described in detail by way of example, it will be appreciated by those skilled in the art that the above examples are for illustration only and are not intended to limit the scope of the present invention. It will be appreciated by those skilled in the art that the above embodiments may be modified without departing from the scope and spirit of the present invention. The scope of the present invention is defined by the appended claims.

Claims

1. An off-road cruise control method based on dual-motor PI control, characterized in that: It includes the following steps: Step S1: When the vehicle controller recognizes that the vehicle enters the off-road cruise mode, the current target gear is identified; Step S2, the vehicle controller calculates the target vehicle speed according to the target gear position; Step S3, the vehicle controller calculates the difference between the target vehicle speed and the actual vehicle speed, and calculates the initial target torque based on the difference using the PI control algorithm; Step S4: The vehicle controller determines whether to distribute the initial target torque to the front motor and the rear motor of the vehicle according to the vehicle state; The vehicle status includes whether the vehicle is in D gear, whether it is in parking state, whether the driver steps on the brake, and whether the driver steps on the accelerator; If the vehicle is in the D gear, not in the parking state, and the driver does not step on the brake or the accelerator, the initial target torque is distributed to the front motor and the rear motor in a certain ratio; If the vehicle is not in D gear or in parking state or the driver steps on the brake, the initial target torque is not distributed to the front motor and the rear motor.

2. The off-road cruise control method based on dual-motor PI control according to claim 1, characterized in that: Step S4 also includes: if the vehicle controller receives a signal that the driver has stepped on the accelerator, the accelerator torque is calculated according to the accelerator size, and the accelerator torque is compared with the initial target torque, and it is determined whether the driver should take over according to the comparison result.

3. The off-road cruise control method based on dual-motor PI control according to claim 2 is characterized in that: If the throttle torque is greater than the initial target torque, the throttle torque is output and the vehicle is taken over by the driver. After the driver releases the accelerator, the vehicle controller looks up the table according to the current actual vehicle speed to obtain the corresponding target negative torque, and distributes the target negative torque to the rear motor to reduce the vehicle speed to near the target speed. The PI control algorithm is then used to calculate the current initial target torque and then distribute it to the front and rear motors.

4. The off-road cruise control method based on dual-motor PI control according to claim 2, characterized in that: If the throttle torque is not greater than the initial target torque, the throttle torque will not be responded to, and the vehicle does not need the driver to take over, and the initial target torque will be distributed to the front motor and the rear motor.

5. The off-road cruise control method based on dual-motor PI control according to claim 1, characterized in that: When the initial target torque is distributed to the front and rear motors of the vehicle, if the vehicle controller receives a steering signal from the vehicle, it obtains the corresponding steering compensation torque based on the current steering angle during steering, and then outputs the steering compensation torque after being superimposed on the initial target torque.

6. The off-road cruise control method based on dual-motor PI control according to claim 5, characterized in that: When the initial target torque is distributed to the front and rear motors of the vehicle, if the vehicle controller receives a slope signal, it will look up the table according to the current slope to obtain the corresponding slope compensation torque, and then superimpose the slope compensation torque with the initial target torque before outputting it.

7. The off-road cruise control method based on dual-motor PI control according to claim 6, characterized in that: When the initial target torque is distributed to the front motor and the rear motor of the vehicle, if the vehicle controller receives the steering signal and the slope signal of the vehicle at the same time, the steering compensation torque and the slope compensation torque are superimposed on the initial target torque and then output.

8. The off-road cruise control method based on dual-motor PI control according to any one of claims 1 to 7, characterized in that: The above certain ratio is 1:1.

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