CN102506160A - Ramp based on longitudinal dynamics and vehicle load identification method - Google Patents

Abstract

The invention discloses a method for identifying slopes and vehicle loads based on longitudinal dynamics. Steps: 1. The shift control unit acquires real-time engine torque and real-time vehicle speed information; 2. The shift control unit makes a validity judgment on the acquired real-time engine torque and real-time vehicle speed information; 3. The shift control unit uses the effective real-time engine torque and real-time vehicle speed information The effective vehicle speed value updates the effective torque and effective vehicle speed at the previous moment; 4. The gear shift control unit performs low-pass filtering on the engine torque; 5. The gear shift control unit uses the filtered engine torque to calculate the acceleration of the vehicle on flat roads; 6. Shift gears The control unit performs differential calculation on the real-time vehicle speed to obtain the actual driving acceleration of the vehicle; 7. The gear shift control unit performs low-pass filtering processing on the actual driving acceleration of the vehicle; 8. The gear shift control unit calculates the road slope and vehicle load value; 9. Shift control The unit uses the current acceleration of the vehicle on flat roads and the actual acceleration of the current vehicle to update the corresponding information at the previous moment.

Description

Slope and Vehicle Load Identification Method Based on Longitudinal Dynamics

technical field

The present invention relates to a method for identifying slopes and vehicle loads, more specifically, the present invention relates to a method for identifying slopes and vehicle loads based on longitudinal dynamics that can improve the adaptability of automatic transmission systems of vehicles to changes in slopes and vehicle loads method.

Background technique

Usually, the shifting strategy of the automatic transmission system of the vehicle is based on the vehicle speed and the throttle opening as the control parameters. It has satisfactory performance on a good level road surface, but in the case of complicated driving conditions, this shifting strategy will produce Shift issues such as shift cycles, unexpected shifts, etc. The reason is that the automatic transmission system does not understand the information of the vehicle itself and its environment. Therefore, the automatic transmission system urgently needs a method for identifying slopes and vehicle loads, so as to increase the comfort, reliability and safety of the automatic transmission system.

There are many methods of slope recognition: there is a slope recognition method based on the judgment of the acceleration interval, which is theoretically feasible, but it needs to calibrate a large amount of data in practice; there is also the acceleration signal measured by the acceleration sensor and the actual acceleration of the vehicle. The identification method of the road slope requires an additional acceleration sensor, which undoubtedly increases the cost of the vehicle.

In view of the above problems, the present invention proposes to accurately identify the road slope and the vehicle load, so that the automatic transmission system of the vehicle has certain adaptability to the changes of the slope and the vehicle load.

Contents of the invention

The technical problem to be solved by the present invention is to overcome the existing problems in the prior art, and provide a slope and vehicle load identification method based on longitudinal dynamics that can improve the adaptability of the vehicle automatic transmission system to the slope and vehicle load changes.

In order to solve the above-mentioned technical problems, the present invention is achieved by adopting the following technical solutions: the steps of the described method for identifying slopes and vehicle loads based on longitudinal dynamics are as follows:

1. The shift control unit obtains real-time engine torque and real-time vehicle speed information through CAN device driver module and CAN information processing module processing and CAN data frame between engine control unit and ABS control unit.

2. The shift control unit judges the validity of the obtained real-time engine torque information: if the engine torque information is invalid, discard the invalid torque and use the effective torque at the previous moment, and if the engine torque information is valid, go to the next step.

At the same time, the shift control unit makes a validity judgment on the obtained real-time vehicle speed information: if the vehicle speed information is invalid, discard the invalid vehicle speed, and use the valid vehicle speed at the previous moment, and transfer to the next step if the vehicle speed information is valid.

3. The shift control unit uses the effective real-time engine torque to update the effective torque at the previous moment, and at the same time, the shift control unit updates the effective vehicle speed at the previous moment with the effective vehicle speed value.

4. The shift control unit performs low-pass filter processing on the engine torque through the engine torque filter module, and the algorithm is as follows:

Y _n =aX _n +(1-a)Y _n-1

Among them: X _n . this sampling value, Y _n-1 . the last filtering output value, a. filtering coefficient, Y _n . the current filtering output value.

5. The shift control unit calculates the acceleration of the vehicle on a flat road by using the filtered engine torque through the calculation module of the vehicle’s flat road acceleration:

滚动阻力系数，C_D.空气阻力系数，A.迎风面积(m²)，v.车速(km/h)，δ.汽车旋转质量换算系数。Where: T _tq . Filtered engine torque (N m), i _g . Transmission ratio of transmission, i ₀ . Gear ratio of final drive, η _T . Mechanical efficiency of drive train, r. Tire rolling radius (m), g. Gravitational acceleration (m/s ² ),

Coefficient of rolling resistance, C _D. Coefficient of air resistance, A. Frontal area (m ² ), v. Vehicle speed (km/h), δ. Conversion factor of vehicle rotating mass.

6. The gear shift control unit performs differential calculation on the real-time vehicle speed through the actual vehicle acceleration calculation module to obtain the actual vehicle acceleration.

7. The shift control unit performs low-pass filtering processing on the actual driving acceleration of the vehicle through the vehicle actual driving acceleration filtering module. The low-pass filtering processing algorithm is as follows:

Y _n =aX _n +(1-a)Y _n-1

Among them: X _n . this sampling value, Y _n-1 . the last filtering output value, a. filtering coefficient, Y _n . the current filtering output value.

8. The gear shift control unit calculates the road slope and vehicle load calculation module by using the current vehicle acceleration on a flat road, the current actual vehicle acceleration, the vehicle acceleration on a flat road at the previous moment, and the actual vehicle acceleration at the previous moment. Vehicle load value:

Among them: i. Road slope value, g. Indicates the acceleration of gravity (m/s ² ), δ. The conversion factor of vehicle rotating mass, Coefficient of rolling resistance, v. current vehicle speed (km/h), Δm. vehicle load (kg), m. mass of the vehicle when it is unloaded (kg), a1 _level , a1 _real . Actual driving acceleration (m/s ² ), a0 _flat , a0 _real . It is the acceleration of the vehicle on flat road at the last moment, and the actual driving acceleration of the vehicle at the last moment (m/s ² ).

9. The shift control unit uses the current acceleration of the vehicle on flat road and the actual acceleration of the current vehicle to update the acceleration of the vehicle on flat road at the previous moment and the actual acceleration of the vehicle at the previous moment.

Compared with prior art, the beneficial effects of the present invention are:

1. The slope and vehicle load identification method based on longitudinal dynamics of the present invention does not need to add additional sensors, and has the characteristics of low cost, simplicity and practicality.

2. The method for identifying slopes and vehicle loads based on longitudinal dynamics in the present invention is simple and efficient and can accurately identify slopes and vehicle loads.

3. The method for identifying slopes and vehicle loads based on longitudinal dynamics in the present invention has versatility and portability, and the method can be applied to other types of automatic transmission systems.

Description of drawings

Below in conjunction with accompanying drawing, the present invention will be further described:

Fig. 1 is the schematic block diagram of the functional module framework of the ramp and vehicle load identification method based on longitudinal dynamics of the present invention;

Fig. 2 is a functional flow diagram of the slope and vehicle load identification method based on longitudinal dynamics according to the present invention.

Fig. 3 is a flow chart of the low-pass filtering processing steps in the slope and vehicle load identification method based on longitudinal dynamics according to the present invention.

Fig. 4 is a curve of simulation experiment results using the longitudinal dynamics-based slope and vehicle load identification method of the present invention.

Fig. 5 is a curve of actual vehicle test results using the slope and vehicle load identification method based on longitudinal dynamics according to the present invention.

Detailed ways

The present invention is described in detail below in conjunction with accompanying drawing:

Referring to Fig. 1, it is a schematic block diagram of the functional module framework of the computer program that implements the ramp based on longitudinal dynamics of the present invention and the vehicle load identification method among the figure, implements the ramp based on longitudinal dynamics of the present invention and The computer program of the vehicle load recognition method is installed and run in the TCU (shift control unit). Implement the functional module frame of the computer program based on the slope of longitudinal dynamics described in the present invention and the vehicle load recognition method by CAN device driver module, CAN information processing module, engine torque filter module, vehicle actual driving acceleration calculation module, vehicle actual It consists of a driving acceleration filtering module, a vehicle acceleration calculation module on flat roads, and a slope and vehicle load calculation module.

In the TCU, the corresponding functional module programs are scheduled to run by the TCU task scheduler. Among them, the CAN device driver module and the CAN information processing module are called in the 1ms periodic task; the engine torque filtering module, the vehicle flat road acceleration calculation module, and the vehicle actual driving acceleration filtering module are called in the 10ms periodic task; the ramp and vehicle load The calculation module and the actual vehicle acceleration calculation module are called in the 100ms periodic task. The shift control unit uses the TCU task scheduler to call the CAN device driver module and the CAN information processing module to process the CAN data frame between the engine control unit and the ABS control unit in the 1ms period task to obtain real-time engine torque and real-time vehicle speed information. The TCU task scheduler calls the engine torque filter module in the 10ms period task to perform low-pass filter processing on the engine torque; the vehicle acceleration calculation module uses the filtered engine torque to calculate the vehicle acceleration; the actual vehicle acceleration filter module The actual driving acceleration is low-pass filtered. The TCU task scheduler calls the vehicle actual driving acceleration module in the 100ms periodic task to perform differential calculation on the real-time vehicle speed to obtain the actual vehicle driving acceleration; the slope and vehicle load calculation module uses the current vehicle flat road driving acceleration, the current vehicle actual driving acceleration and the previous The acceleration of the vehicle on the flat road at the moment and the actual acceleration of the vehicle at the previous moment are finally calculated to calculate the exact value of the road slope and vehicle load.

Referring to Fig. 2, it is a flow chart of the slope and vehicle load identification method based on longitudinal dynamics among the figure, and the method comprises the following steps:

1. The shift control unit (TCU) calls the CAN device driver module and the CAN information processing module to process the CAN data frame between the engine control unit and the ABS control unit through the TCU task scheduler in the 1ms cycle task, and obtains real-time engine torque and real-time Vehicle speed information.

2. The shift control unit (TCU) judges the validity of the obtained real-time engine torque information according to the effective interval of the engine torque information defined by the CAN communication protocol: if the engine torque information is invalid, discard the invalid torque and use the effective torque at the previous moment. If the engine torque information is valid, go to the next step.

At the same time, the shift control unit (TCU) judges the validity of the obtained real-time vehicle speed information according to the effective range of vehicle speed information defined by the CAN communication protocol: if the vehicle speed information is invalid, discard the invalid vehicle speed and use the valid vehicle speed at the previous moment. If the vehicle speed information is valid, proceed to the next step.

3. The shift control unit (TCU) updates the effective torque at the last moment with the effective real-time engine torque value. At the same time, the shift control unit (TCU) updates the effective vehicle speed at the last moment with the effective vehicle speed value.

4. The shift control unit (TCU) calls the engine torque filter module to perform low-pass filter processing on the engine torque in the 10ms period task through the TCU task scheduler. Using digital low-pass filtering method, its algorithm is as follows:

Y _n =aX _n +(1-a)Y _n-1

Among them: X _n . this sampling value, Y _n-1 . the last filtering output value, a. filtering coefficient, Y _n . the current filtering output value.

5. The shift control unit (TCU) calls the vehicle acceleration calculation module on flat roads through the TCU task scheduler in the 10ms periodic task, and uses the filtered engine torque to calculate the vehicle acceleration on flat roads. The calculation formula is as follows:

滚动阻力系数，C_D.空气阻力系数，A.迎风面积(m²)，v.车速(km/h)，δ.汽车旋转质量换算系数。Where: T _tq . Filtered engine torque (N m), i _g . Transmission ratio of transmission, i ₀ . Gear ratio of final drive, η _T . Mechanical efficiency of drive train, r. Tire rolling radius (m), g. Gravitational acceleration (m/s ² ),

Coefficient of rolling resistance, C _D. Coefficient of air resistance, A. Frontal area (m ² ), v. Vehicle speed (km/h), δ. Conversion factor of vehicle rotating mass.

6. The shift control unit (TCU) calls the vehicle actual driving acceleration calculation module in the 100ms cycle task through the TCU task scheduler, and performs differential calculation on the real-time vehicle speed to obtain the actual vehicle driving acceleration. The possible range of the differential calculation time interval is 50ms-500ms, and the specific time interval should be determined according to the real-time vehicle speed accuracy collected by the shift control unit (TCU). In this embodiment, the differential calculation time interval is taken as 100ms.

7. The shift control unit (TCU) calls the vehicle actual driving acceleration filter module in the 10ms period task through the TCU task scheduler to perform low-pass filtering processing on the actual driving acceleration of the vehicle. The low-pass filtering processing algorithm is as follows:

Y _n =aX _n +(1-a)Y _n-1

Among them: X _n . this sampling value, Y _n-1 . the last filtering output value, a. filtering coefficient, Y _n . the current filtering output value.

8. The shift control unit (TCU) calls the ramp and vehicle load calculation module in the 100ms cycle task through the TCU task scheduler, and uses the current vehicle acceleration on a flat road, the actual acceleration of the current vehicle and the acceleration of the vehicle on a flat road at the previous moment , The actual driving acceleration of the vehicle at the last moment is finally calculated to calculate the exact value of the road slope and vehicle load. The longitudinal dynamics derivation used is as follows:

滚动阻力系数，v.车辆当前车速(km/h)，Δm.车辆载荷(kg)，m.车辆空载时质量(kg)，a1_平、a1_实.分别是当前车辆平路行驶加速度、当前车辆实际行驶加速度(m/s²)。a0_平、a0_实.分别是上一时刻车辆平路行驶加速度、上一时刻车辆实际行驶加速度(m/s²)。Among them: i. Road slope value, g. Indicates the acceleration of gravity (m/s ² ), δ. The conversion factor of vehicle rotating mass,

Coefficient of rolling resistance, v. current speed of the vehicle (km/h), Δm. vehicle load (kg), m. mass of the vehicle when it is unloaded (kg), a1 _level and a1 _real . The actual driving acceleration of the vehicle (m/s ² ). a0 _level , a0 _real . They are the acceleration of the vehicle on flat road at the last moment and the actual acceleration of the vehicle at the last moment (m/s ² ).

9. The shift control unit (TCU) uses the current vehicle acceleration on a flat road and the current actual acceleration of the vehicle to update the vehicle acceleration on a flat road at the previous moment and the actual acceleration of the vehicle at the previous moment.

Referring to FIG. 3 , it is a flow chart of the low-pass filtering processing steps in the longitudinal dynamics-based slope and vehicle load identification method of the present invention. In this embodiment, both the vehicle actual driving acceleration filtering module and the engine torque filtering module use this filtering algorithm. Although the same filtering algorithm is used, the filter coefficient a of the two filter modules is different, and the selection of the filter coefficient a should be based on experimental calibration.

The algorithm consists of the following steps:

1. The corresponding filtering module acquires the current sampling value X _n .

2. The corresponding filter module calculates the product of the filter coefficient a and the sampling value X _n of this time.

3. The corresponding filtering module calculates the product of (1-a) and the last filtering output value Y _n-1 .

4. The corresponding filter module calculates the current filter output value Y _n .

5. The corresponding filtering module updates the last filtering output value Y _n-1 to the current filtering output value Y _n .

Simulation and test analysis

Referring to Fig. 4 and Fig. 5, for the slope and vehicle load identification method based on longitudinal dynamics described in the present invention, utilize MATLAB/SIMULINK to establish the whole vehicle dynamics model of mechanical automatic transmission vehicle, and carried out on this model Verification of slope and vehicle load identification algorithm based on longitudinal dynamics. The dynamics model simulates the driving condition of the vehicle under certain working conditions, and recognizes the road slope and the vehicle load through the method of the invention. The specific working conditions are: the throttle opening value is kept at 50%, the road gradient value is 8%, the vehicle mass is 1300kg, the load is 100kg, and the vehicle unladen mass is 1200kg. The verification result curve of the dynamic simulation model is shown in Figure 4. The vehicle experienced 1-2 upshifts between 6s and 7s. At this moment, the calculated acceleration of the vehicle on a flat road and the actual acceleration of the vehicle fluctuate to a certain extent, which affects the road gradient. and vehicle load identification, so the road gradient and vehicle load should no longer be identified during a gear change. It can be seen from the figure that in the range of 1st gear and 2nd gear, there is always a difference between the acceleration of the vehicle on a flat road and the actual acceleration of the vehicle. The slope and vehicle load identification method based on longitudinal dynamics in the present invention can accurately identify the road slope value of 0.08 and the vehicle load value of 100kg.

On the basis of the dynamic model simulation verification of the slope and vehicle load identification method based on longitudinal dynamics in the present invention, a real vehicle road test is carried out to further verify the real-time identification effect of the slope and vehicle load identification method based on longitudinal dynamics , the test vehicle is equipped with a 5-speed AMT transmission. The unloaded mass of the vehicle is 1125kg. In the test, there is a driver in the car, and the monitoring equipment of the host computer is installed in the vehicle. The total mass of the driver and the monitoring equipment is 75kg. The monitoring software of the host computer is used VECTOR CANAPE6.5. The test road is a bridge with a length of 120m, including an uphill section of 50m, a flat section of 20m, and a downhill section of 50m. The slope angle of the ramp is about 5° (the slope value is about 0.1). The road test result curve is shown in Figure 5. The identification curve more accurately reflects the test road slope and test vehicle load.

The results of dynamic model simulation and real vehicle road test have verified that the method for identifying slopes and vehicle loads based on longitudinal dynamics in the present invention is feasible.

Furthermore, the present invention is not limited to the above-disclosed embodiments, but covers various modifications and equivalents included within the spirit and scope of the appended claims.

Claims (1)

1. one kind based on vertical dynamic (dynamical) ramp and car load identifying method, it is characterized in that, described following based on vertical dynamic (dynamical) ramp and car load identifying method step:

1) shift change controller obtains real-time Engine torque and real-time speed information through CAN Frame between CAN device driver module and the processing of CAN message processing module and control unit of engine and the ABS control unit;

2) shift change controller is done the validity judgement to the real-time Engine torque information of obtaining: if Engine torque information is invalid, give up invalid moment of torsion, be carved with the effect moment of torsion in the use for the moment, if Engine torque information effectively then changes next step over to;

Simultaneously, shift change controller is done validity to the real-time speed information that obtains and is judged: invalid like speed information, give up the invalid speed of a motor vehicle, and be carved with the effect speed of a motor vehicle in the use for the moment, if speed information effectively then changes next step over to;

3) shift change controller upgrades to go up with the efficient real time Engine torque and is carved with the effect moment of torsion for the moment, and simultaneously, shift change controller upgrades to go up with effective vehicle speed value and is carved with the effect speed of a motor vehicle for the moment;

4) shift change controller is done low-pass filtering treatment through the Engine torque filtration module to Engine torque, and its algorithm is following:

Y _n＝aX _n+(1-a)Y _n-1

Wherein: X _n. this sampled value, Y _N-1. last time filtering output value, a. filter factor, Y _n. this filtering output value;

5) shift change controller utilizes filtering rear engine torque arithmetic vehicle flat pavement running acceleration through vehicle flat pavement running acceleration calculation module:

Wherein: T _Tq. filtering rear engine moment of torsion (Nm), i _g. transmission ratio, i ₀. main reducing gear velocity ratio, η _T. mechanical efficiency of power transmission, r. tire rolling radius (m), g. gravity accleration (m/s ²),

Coefficient of rolling resistance, C _D. coefficient of air resistance, A. wind-exposuring area (m ²), the v. speed of a motor vehicle (km/h), δ. the automobile correction coefficient of rotating mass;

6) shift change controller is done differential calculation through vehicle actual travel acceleration calculation module to the real-time speed of a motor vehicle, obtains vehicle actual travel acceleration;

7) shift change controller carries out low-pass filtering treatment through vehicle actual travel acceleration filtration module to vehicle actual travel acceleration, and the low-pass filtering treatment algorithm is following:

Y _n＝aX _n+(1-a)Y _n-1

Wherein: X _n. this sampled value, Y _N-1. last time filtering output value, a. filter factor, Y _n. this filtering output value;

8) shift change controller utilizes current vehicle flat pavement running acceleration, current vehicle actual travel acceleration, a last moment vehicle flat pavement running acceleration and a last moment vehicle actual travel acceleration calculation to go out road grade and car load value through ramp and car load computing module:

Wherein: i. road grade value, g. shows gravity accleration (m/s ²), δ. the automobile correction coefficient of rotating mass,

Coefficient of rolling resistance, v. vehicle current vehicle speed (km/h), Δ m. car load (kg), quality (kg) when the m. vehicle is unloaded, a1 _Flat, a1 _Real. be current vehicle flat pavement running acceleration, current vehicle actual travel acceleration (m/s ²), a0 _Flat, a0 _Real. be a last moment vehicle flat pavement running acceleration, last vehicle actual travel acceleration (m/s constantly ²);

9) shift change controller upgrades a last moment vehicle flat pavement running acceleration and last vehicle actual travel acceleration constantly with current vehicle flat pavement running acceleration and current vehicle actual travel acceleration.

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