Slope-holding torque high-precision estimation method, slope-holding estimation system and motor vehicle slope-holding starting control method

Abstract

The invention provides a slope-holding torque high-precision estimation method, a slope-holding estimation system and a motor vehicle slope-holding starting control method. The hill-holding torque high-precision estimation method is realized based on the following hill-holding estimation system: the system takes a vehicle control unit as a control center and comprises an attitude acquisition part connected with an acquisition bus of the vehicle control unit, and the attitude acquisition part comprises three attitude sensing modules respectively mounted on a front axle, a rear axle and the middle part of a vehicle; the estimation method comprises the steps that a whole vehicle controller obtains the starting torque required by a ramp of the motor vehicle according to the motion posture information of a front axle, a rear axle and the middle part of the vehicle, which is obtained by a resolving group model and a three-posture sensing module in real time, and the motor vehicle hill-holding starting control method adopts a control method of organically combining motor hill-holding and braking hill-holding; and when the braking hill-holding fails, the motor hill-holding instantly intervenes, so that the motor vehicle stably stops on the ramp, and the safety and the reliability of the whole vehicle are improved.

Description

Technical Field

[0001] The present invention relates to an electronic control method and an electronic control system for a motor vehicle with electric motor power, and in particular to a method for estimating the slope holding torque, a method for controlling a hill start, and a control system for the motor vehicle, i.e., a new energy vehicle. Background Art

[0002] Electric vehicles use motor-held hill-starting, and the process of starting on a slope is: lightly press the brake and then release it. After the vehicle controller detects the vehicle speed in the opposite direction of the gear, it will output the corresponding torque to keep the vehicle stationary on the slope. The prerequisite for the motor-held hill-starting logic is that the motor speed in the opposite direction of the motor vehicle gear must be detected. Starting on a large road slope will inevitably result in obvious backward sliding, which is very likely to cause a vehicle collision accident. More importantly, the current motor vehicle motor-held hill-starting control method estimates the starting torque on a slope only based on a unified method that regards Figure 1 The static inclination model state is used to calculate, and for example Figure 2 When the vehicle is in a complex road environment as shown in the figure, there will be a technical problem that the parking start torque estimation result is far from the actual required torque, resulting in the vehicle sliding backward or rushing forward when starting from a slope. Summary of the invention

[0003] The purpose of the invention of this patent application is to eliminate the problem of slope starting in the existing hill-holding start control technology that the estimated value of the parking start torque is greatly different from the actual required torque, and the slope start is prone to slipping or rushing forward. A high-precision estimation method for the hill-holding torque and its hill-holding estimation system are provided to enable a motor vehicle to start safely and smoothly on a slope.

[0004] Another invention purpose of this patent application is to solve the technical problems of hill-holding safety and reliability existing in a single motor hill-holding operation, and to provide a hill-holding starting control method for a motor vehicle.

[0005] The technical solution of the high-precision estimation method of the slope-holding torque provided by this patent application mainly includes: a high-precision estimation method of the slope-holding torque, which is implemented based on the following slope-holding estimation system:

[0006] The hill-holding estimation system is composed of a vehicle controller as a control center and a posture acquisition unit connected to a vehicle controller acquisition bus;

[0007] The attitude acquisition unit includes three attitude sensing modules IMU installed on the front axle, rear axle and middle part of the vehicle respectively;

[0008] The estimation method is:

[0009] In the first step, the three-attitude sensing module IMU senses in real time and calculates the motion attitude information of the front axle, rear axle and the middle of the vehicle, including the angles θ1 and θ2 between the motion trend direction of the front axle and rear axle and the direction of gravity;

[0010] In the second step, the vehicle controller including the following solution group model solves and obtains the starting torque required for the motor vehicle on the slope:

[0011] F r1 =M1g sinθ1×0.0076—Formula (1)

[0012] F r2 =M2g cos(θ2-90)×0.0076—Formula (2)

[0013]

[0014] in,

[0015] M1 is the front axle load;

[0016] M2 is the rear axle load;

[0017] F q The wheel force required for starting on a slope;

[0018] θ is the angle between the vehicle’s x-axis and the horizontal;

[0019] g is the acceleration due to gravity;

[0020] T q The torque required for starting on a slope;

[0021] r is the static radius of the tire;

[0022] i is the transmission ratio of the power system.

[0023] One of the preferred options of the above-mentioned overall technical solution is that the hill-holding estimation system also includes a video acquisition unit and a passenger flow sensing unit connected to the vehicle controller acquisition bus.

[0024] The present patent application also provides a hill-holding estimation system for implementing the hill-holding torque high-precision estimation method. The hill-holding estimation system uses a vehicle controller as a control center and includes a posture acquisition unit connected to an acquisition bus of the vehicle controller;

[0025] The attitude acquisition unit includes three attitude sensing modules IMU, which are respectively installed on the front axle, the rear axle and the middle of the vehicle.

[0026] One of the preferred options of the above overall technical solution is that the attitude sensing module IMU is selected to be a three-dimensional motion attitude measurement module IMU composed of a three-axis gyroscope, a three-axis accelerometer and a three-axis geomagnetic field sensor.

[0027] The present patent application provides a method for controlling a motor vehicle starting from a hill, wherein the control steps of the method include:

[0028] S01: The vehicle is in high voltage power-on state:

[0029] S02: First determine whether the vehicle speed is 0 and the gear position is ≠ neutral. If yes, jump to the next step S03; if not, jump back to S01;

[0030] S03 determines whether the current slope is greater than the calibrated slope x, where x is 1-3°. If yes, go to the next step S04, otherwise, jump to S09;

[0031] S04 determines whether the driver has pressed the brake deeply and maintained the brake for more than 3 seconds. If yes, the process goes to the next step S05 of temporarily stopping on a slope. If not, the process jumps to S13;

[0032] S05 goes to the temporary stopping and holding hill state, and then goes to the next step S06, and at the same time, the vehicle controller estimates the holding hill torque value according to the information collected by the posture collection unit;

[0033] S06 determines that the requested torque is greater than the estimated torque value for holding the slope. If yes, the process goes to the next step S07. If not, the process goes back to S05.

[0034] S07 releases the temporary stop on the slope state, and then goes to the next step S08;

[0035] S08 determines whether the vehicle speed is less than 0, if yes, then go to the next step S09, if not, then jump to S10;

[0036] S09 switches to the motor hill-standing state and enters S11;

[0037] S10 switches to driving state and jumps back to S01;

[0038] S11 determines that the requested torque is greater than the estimated torque value for holding the slope. If yes, the process goes to S12. If not, the process goes to S09.

[0039] S12 releases the motor to hold the slope, and jumps to S08;

[0040] In S13, the vehicle controller releases the service brake state and jumps back to S01.

[0041] The high-precision estimation method of the hill-holding torque, its hill-holding estimation system and the technical scheme of the motor vehicle hill-holding start control method disclosed in this patent application have a more accurate hill-start torque estimated by the method, and overcome the technical defect of the existing hill-start control technology that the vehicle may slide backward or rush forward when starting on a slope due to the large difference between the estimated value and the actual required torque value, so that the motor vehicle can start smoothly on the slope. In addition, the motor vehicle hill-holding start control method adopts a control method that organically combines the motor hill-holding and the brake hill-holding. When the brake hill-holding fails, the motor hill-holding intervenes instantly, so that the motor vehicle can be stably stopped on the slope, thereby providing safety and reliability for the entire vehicle. BRIEF DESCRIPTION OF THE DRAWINGS

[0042] Figure 1 Schematic diagram of the existing static tilt torque estimation model.

[0043] Figure 2 The model diagram shown is an example of a complex parking condition using an existing parking and starting torque estimation model.

[0044] Figure 3 yes Figure 2 The actual vehicle parking state diagram.

[0045] Figure 4 This is the model principle diagram of the special ramp of this high-precision estimation method of slope-standing torque.

[0046] Figure 5 This is the model principle diagram of the application example of this high-precision estimation method of slope-holding torque.

[0047] Figure 6 It is a control flow chart of the hill-start control method for a motor vehicle. DETAILED DESCRIPTION

[0048] The technical contents of the high-precision estimation method of the hill-holding torque, its hill-holding estimation system and the hill-holding start control method for a motor vehicle will be described in detail below through specific embodiments.

[0049] This high-precision estimation method of the holding torque is based on the following holding torque estimation system:

[0050] The hill-holding estimation system is composed of a vehicle controller as a control center and a posture acquisition unit connected to an acquisition bus of the vehicle controller.

[0051] The vehicle controller is the original central processing system of the motor vehicle, which is equivalent to the "brain" of the vehicle. Its main control functions include collecting the driver's operating instructions, including gear, throttle, brake, power mode, etc., and comprehensively analyzing the current state of the vehicle to calculate the driver's control intention and the comprehensive state of the vehicle, and making the best coordinated control. The main functions of the current vehicle controller include vehicle drive control, optimal control of braking energy, energy management of the vehicle, maintenance and management of the CAN network, diagnosis and processing of faults, vehicle status monitoring, driving records, etc.

[0052] The attitude acquisition unit includes three attitude sensing module IMUs, including a front axle attitude sensing module IMU installed on the front axle of the vehicle, a rear axle attitude sensing module IMU installed on the rear axle of the vehicle, and a middle attitude sensing module IMU installed in the middle of the vehicle. The attitude sensing module IMU has its own MCU for real-time solution to obtain the motion attitude information of the front axle, rear axle and middle of the vehicle, which can be combined with the slope data calibrated by the GPS real-time vehicle position information to further provide the angles θ1 and θ2 between the motion trend direction of the front axle and the rear axle and the gravity direction required for the following torque estimation, and transmit them to the vehicle controller that already contains the following solution group model via the CAN network.

[0053] The attitude sensing module IMU can use the currently mature high-performance three-dimensional motion attitude measurement module IMU, which mainly includes a three-axis gyroscope, a three-axis accelerometer and a three-axis geomagnetic field sensor.

[0054] If the motor vehicle is a passenger car, bus or other type of vehicle, in order to obtain more accurate solution parameters, such as the front and rear axle loads M1 and M2, the slope estimation system also includes a video acquisition unit and a passenger flow sensing unit connected to the vehicle controller acquisition bus.

[0055] The motor vehicle of this embodiment is parked at Figure 4 On the special ramp shown, we can see that the slope angles of the front wheels and the rear wheels are obviously different, so their slope-starting forces, that is, their movement trends, are also different, resulting in the angles θ1 and θ2 between the movement trend directions of the front axle and the rear axle and the direction of gravity being obviously different.

[0056] by Figure 5 To illustrate the embodiment, known data include: M1 is 6000kg, M2 is 8000kg, wheelbase is 6 meters, the slope is 20%, the rear axle speed ratio is 5.125, and the tire radius is 0.506 meters. The rear wheels of the motor vehicle are in contact with the horizontal plane and the ramp at the same time, but are not subjected to force on the inclined surface.

[0057] In the first step, the vehicle controller collects the real-time calculated values ​​of the IMU of each attitude sensing module, and the front axle angle θ1 is 101°, the rear axle θ2 is 90°, and θ is 11°;

[0058] In the second step, the vehicle controller including the following solution group model solves and obtains the starting torque required for the motor vehicle on the slope:

[0059] F r1 =M1g sinθ1×0.0076—Formula (1)

[0060] F r2 =M2g cos(θ2-90)×0.0076—Formula (2)

[0061]

[0062] Among them, M1 is the front axle load, M2 is the rear axle load, and F q represents the wheel force required for starting on a slope, θ represents the angle between the vehicle's x-axis and the horizontal direction, g represents the acceleration due to gravity, and T q It represents the torque required for starting on a slope, r represents the static radius of the tire, and i represents the transmission ratio of the power system.

[0063] The torque required for ramp starting obtained by solving the above mathematical model group is T q =1188Nm.

[0064] Compared with the existing torque estimation method, the existing torque estimation method determines that the front and rear wheels of the motor vehicle are in the same ramp state at this time, that is, the front axle θ1 and the rear axle θ2 are equal, both 101°. Even through the solution group model, the starting torque solved is T q =2685Nm. The torque obtained by the existing estimation method is 1497Nm greater than the actual required value, and the error is as high as 126%. Therefore, according to the existing starting torque estimation method, it is inevitable to generate a forward thrust.

[0065] The motor vehicle hill-start control method provided in this patent application is based on the starting torque T obtained by the vehicle controller. q , the motor output torque is controlled via the CAN bus. When the vehicle is on a slope and in the forward gear, the vehicle controller controls the motor output torque ≥ T q , and then release the brake to achieve a smooth motor ramp start. The method includes the following control steps:

[0066] S01: The vehicle is in high voltage power-on state;

[0067] This is the starting condition of the entire hill-holding control process, that is, the vehicle must have been started and is in a drivable state, and the system has not detected any faults. Only when this starting condition is met can the next step of the process be continued.

[0068] S02: First determine whether the vehicle speed is 0 and the gear position is ≠ neutral. If yes, jump to the next step S03; if not, jump back to S01.

[0069] Determining whether the vehicle is in a stopped state and not in neutral is a prerequisite for performing hill-holding control and is a judgment step to ensure that the vehicle is in the correct state to execute hill-holding control; if the vehicle speed is not 0 or the gear is in neutral, the hill-holding control requirement is not met and it is necessary to return to the starting state S01.

[0070] S03: Determine whether the current slope is greater than the calibrated slope x, where x is 1-3°. If yes, go to the next step S04; if not, jump to S09.

[0071] Determine whether the current slope of the vehicle exceeds the calibrated slope x. If the actual slope exceeds the calibrated value, it means that the vehicle needs to perform hill start control, otherwise it directly jumps to the motor hill-staying state S09.

[0072] S04: Determine whether the driver has pressed the brake deeply and maintained the brake for more than 3 seconds. If so, go to the next step S05 of temporarily stopping on the slope. If not, jump to S13.

[0073] If the driver presses the brake pedal deeply and holds it for more than 3 seconds, it means that the driver intends to enter a temporary parking state.

[0074] S05: Entering the temporary stop and slope holding state, and then proceeding to the next step S06, at the same time, the vehicle controller estimates the torque value required for the slope holding state based on the information collected by the posture acquisition unit. This step is the starting step of the temporary stop and slope holding state, and provides the necessary torque value for the subsequent exit from the slope holding judgment.

[0075] S06: Determine whether the motor output torque is greater than the estimated slope-holding torque value. If so, go to the next step S07; if not, jump back to S05.

[0076] S07: releasing the temporary stopping and holding hill state, that is, when the current requested torque of the vehicle is greater than the estimated holding hill torque value, the temporary stopping and holding hill state is released, and then the process goes to the next step S08.

[0077] S08: Determine whether the vehicle speed is less than 0, if yes, go to the next step S09, if not, jump to S10.

[0078] This step is used to determine whether the vehicle is sliding backward. If the vehicle speed is less than the D gear, it means that the vehicle may be sliding backward and needs to enter the motor hill-holding state of S09; otherwise, it means that the vehicle is in a normal driving state.

[0079] S09: Switch to the motor hill-holding state and enter S11.

[0080] If the vehicle starts to slide backward, it will enter the motor holding state, and the motor will provide braking torque to keep the vehicle stable on the slope.

[0081] S10: Switch to driving state and jump back to S01.

[0082] This indicates that the vehicle is in a normal driving state, and the hill-holding control process can be exited and returned to the starting S01.

[0083] S11: Determine whether the motor output torque is greater than the estimated slope-holding torque value. If so, proceed to S12; if not, jump to S09.

[0084] In the motor holding hill state, it is determined whether the vehicle's current requested torque is greater than the estimated holding hill torque value. If so, the motor holding hill is released; otherwise, the motor holding hill state is maintained, that is, S09.

[0085] S12: Release the motor to hold the slope, and jump to S08.

[0086] According to the judgment result of S11, if it is yes, the motor is released from the hill-staying state, and the process returns to S08, and the process continues backward.

[0087] S13: The vehicle controller releases the service brake state and jumps back to S01.

[0088] If the driver does not step on the brake deeply and keep the brake on for more than 3 seconds, the vehicle controller will release the service brake state and return to the starting state S01.

Claims

1. A high-precision method for estimating torque on a hill, characterized in that: The estimation method is based on the following standing slope estimation system: The hill-holding estimation system is composed of a vehicle controller as a control center and a posture acquisition unit connected to a vehicle controller acquisition bus; The attitude acquisition unit includes three attitude sensing modules IMU installed on the front axle, rear axle and middle part of the vehicle respectively; The estimation method is: In the first step, the three-attitude sensing module IMU senses in real time and calculates the motion attitude information of the front axle, rear axle and the middle of the vehicle, including the angles θ1 and θ2 between the motion trend direction of the front axle and rear axle and the direction of gravity; In the second step, the vehicle controller including the following solution group model solves and obtains the starting torque required for the motor vehicle on the slope: F r1 =M1gsinθ1×0.0076—Formula (1) F r2 =M2gcos(θ2-90)×0.0076—Formula (2) in, M1 is the front axle load; M2 is the rear axle load; F q The wheel force required for starting on a slope; θ is the angle between the vehicle’s x-axis and the horizontal; g is the acceleration due to gravity; T q The torque required for starting on a slope; r is the static radius of the tire; i is the transmission ratio of the power system.

2. The high-precision estimation method for hill-holding torque according to claim 1 is characterized in that: The hill-staying estimation system also includes a video acquisition unit and a passenger flow sensing unit connected to the vehicle controller acquisition bus.

3. A hill-holding torque estimation system implementing the high-precision hill-holding torque estimation method according to any one of claims 1-2, characterized in that: The slope estimation system uses the vehicle controller as the control center, and includes a posture acquisition unit connected to the vehicle controller acquisition bus; The attitude acquisition unit includes three attitude sensing modules IMU, which are respectively installed on the front axle, the rear axle and the middle of the vehicle.

4. The hill-holding estimation system according to claim 3, characterized in that: The attitude sensing module IMU is composed of a three-dimensional motion attitude measurement module IMU including a three-axis gyroscope, a three-axis accelerometer and a three-axis geomagnetic field sensor.

5. A method for controlling a motor vehicle starting on a hill, characterized in that: The control steps of the method include: S01: The vehicle is in high voltage power-on state: S02: First determine whether the vehicle speed is 0 and the gear position is ≠ neutral. If yes, jump to the next step S03; if not, jump back to S01; S03 determines whether the current slope is greater than the calibrated slope x, where x is 1-3°. If yes, go to the next step S04, otherwise, jump to S09; S04 determines whether the driver has pressed the brake deeply and maintained the brake for more than 3 seconds. If yes, the process goes to the next step S05 of temporarily stopping on a slope. If not, the process jumps to S13; S05 goes to the temporary stopping and holding hill state, and then goes to the next step S06, and at the same time, the vehicle controller estimates the holding hill torque value according to the information collected by the posture collection unit; S06 determines that the requested torque is greater than the estimated torque value for holding the slope. If yes, the process goes to the next step S07. If not, the process goes back to S05. S07 releases the temporary stop on the slope state, and then goes to the next step S08; S08 determines whether the vehicle speed is less than 0, if yes, then go to the next step S09, if not, then jump to S10; S09 switches to the motor hill-standing state and enters S11; S10 switches to driving state and jumps back to S01; S11 determines that the requested torque is greater than the estimated torque value for holding the slope. If yes, the process goes to S12. If not, the process goes to S09. S12 releases the motor to hold the slope, and jumps to S08; In S13, the vehicle controller releases the service brake state and jumps back to S01.

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