JP2014227141A - Vehicle behavior control device and vehicle state estimation device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To perform appropriate side slip suppression control according to a loaded state and a lightly loaded state while suppressing an increase in cost.SOLUTION: A vehicle behavior control device 10 includes: a steering torque sensor 14 for detecting steering torque; an EPS_ECU 24 for generating assist torque; a steering angle sensor 16 for detecting a steering angle; a front wheel lateral force estimation part 28 for estimating front wheel lateral force based on the steering torque, assist torque and steering angle; a vehicle lateral acceleration sensor 18 for detecting vehicle lateral acceleration; a front shaft weight estimation part 30 for estimating front shaft weight based on the front wheel lateral force and the vehicle lateral acceleration; a stability factor determination part 32 for determining a stability factor showing turning characteristics of the vehicle based on the front shaft weight; and side slip suppression control means 36 for performing vehicle side slip suppression control using the stability factor.

Description

  The present invention relates to a vehicle behavior control device that stabilizes the behavior of a vehicle and a vehicle state estimation device that estimates a front axle weight of the vehicle.

  Conventionally, a vehicle behavior control device that stabilizes the behavior of a vehicle is known. The vehicle behavior control device compares the target yaw rate calculated based on the vehicle speed and the turning angle with the actual yaw rate, and controls the braking force and engine output according to the comparison result to suppress vehicle side slip. In this way, the behavior of the vehicle is stabilized.

  In the vehicle behavior control device, an index value representing a turning characteristic of a vehicle called “stability factor” is used to calculate a target yaw rate. This stability factor shows a different value depending on the total vehicle weight. In a passenger car with a small maximum load capacity, the stability factor hardly changes between a light load state with a small load and a load state with a large load. Therefore, even if the stability factor is a fixed value, a substantially accurate target yaw rate can be calculated, and side slip suppression control can be appropriately performed.

  On the other hand, in a loading system vehicle such as a truck, the stability factor in a loaded state is significantly different from that in a lightly loaded state. Therefore, if side slip suppression control is performed using the stability factor in the light load state when the vehicle is in a loaded state, the target yaw rate will not be a value that is really required for side slip suppression control, so appropriate side slip suppression is performed. Control may not be possible.

  As a countermeasure against such a problem, a vehicle behavior control device conventionally provided with a load meter for detecting the load of the vehicle on the vehicle and configured to set the stability factor based on the detection result of the weight meter is provided. It has been proposed (see, for example, Patent Document 1).

JP 2010-253978 A

  However, the vehicle behavior control device as described above tends to be costly because a load meter needs to be added to the vehicle.

  The present invention has been made in view of such a situation, and an object of the present invention is to provide a technique capable of performing appropriate skid suppression control according to the loaded state and the lightly loaded state while suppressing an increase in cost. There is.

  In order to solve the above-described problems, a vehicle behavior control device according to an aspect of the present invention includes a steering torque detection unit that detects a steering torque, an assist torque generation unit that generates an assist torque, and a steering angle detection that detects a steering angle. Means, front wheel lateral force estimating means for estimating front wheel lateral force based on steering torque, assist torque and steering angle, vehicle lateral acceleration detecting means for detecting vehicle lateral acceleration, and based on front wheel lateral force and vehicle lateral acceleration. Front axle weight estimating means for estimating the front axle weight, stability factor determining means for determining a stability factor representing the turning characteristic of the vehicle based on the front axle weight, and vehicle side slip suppression control using the stability factor Side slip suppression control means for performing

  You may further provide the memory | storage means to memorize | store the relationship between a front axle weight and a stability factor. The stability factor determination means may determine the stability factor with reference to the relationship stored in the storage means.

  Another aspect of the present invention is a vehicle state estimation device that estimates a front axle weight of a vehicle. This device includes a steering torque detecting means for detecting a steering torque, an assist torque generating means for generating an assist torque, a steering angle detecting means for detecting a steering angle, and a front wheel side based on the steering torque, the assist torque, and the steering angle. Front wheel lateral force estimation means for estimating force, vehicle lateral acceleration detection means for detecting vehicle lateral acceleration, and front axle weight estimation means for estimating front axle weight based on front wheel lateral force and vehicle lateral acceleration. By switching the stability factor according to the front axle weight estimated by the vehicle state estimation device, it is possible to perform appropriate skid suppression control.

  ADVANTAGE OF THE INVENTION According to this invention, the technique which can perform appropriate skid suppression control according to a loading state and a light loading state can be provided, suppressing the increase in cost.

It is a figure for demonstrating the vehicle behavior control apparatus which concerns on embodiment of this invention. It is a figure which shows an example of the map data which prescribed | regulated the relationship between a front axle weight and a stability factor. It is a flowchart for demonstrating control of the vehicle behavior control apparatus which concerns on this embodiment.

  Hereinafter, embodiments for carrying out the present invention will be described in detail with reference to the drawings.

  FIG. 1 is a diagram for explaining a vehicle behavior control apparatus 10 according to an embodiment of the present invention. The vehicle behavior control apparatus 10 shown in FIG. 1 detects the vehicle state based on information from various sensors, and stabilizes the vehicle behavior during turning by controlling the braking force and the driving force. This is a system that suppresses the side slip of the vehicle during turning (also referred to as VSC (Vehicle Stability Control)).

  FIG. 1 illustrates functional blocks involved in the above-described vehicle behavior stabilization control. Each block shown here can be realized in hardware by an element and a mechanical device including a computer CPU and memory, and in software by a computer program or the like. It is drawn as a functional block to be realized. Therefore, those skilled in the art will understand that these functional blocks can be realized in various forms by a combination of hardware and software.

  As shown in FIG. 1, the vehicle behavior control device 10 includes a vehicle behavior control ECU (Electronic Control Unit) 12, a steering torque sensor 14, a steering angle sensor 16, a vehicle lateral acceleration sensor 18, and a wheel speed sensor 20. The yaw rate sensor 22 and the EPS_ECU 24 are provided.

  The steering torque sensor 14 detects the steering torque MT of the steering wheel by the driver. The steering angle sensor 16 detects the steering angle δ of the steering wheel by the driver. The vehicle lateral acceleration sensor 18 detects the vehicle lateral acceleration Gy. The yaw rate sensor 22 detects the yaw rate (referred to as “actual yaw rate”) γr actually generated in the vehicle. The detection values of these sensors are input to the vehicle behavior control ECU 12.

  The steering torque sensor 14 and the steering angle sensor 16 may be provided in the vehicle as components of an electric power steering (EPS) device. The EPS_ECU 24 calculates an assist current based on the steering torque MT from the steering torque sensor 14 and the vehicle speed, and generates an assist torque AT by controlling a current supplied to a power steering motor (not shown). By adding the assist torque AT to the steering torque MT, the driver can perform steering with a small force. Information on the assist torque AT generated by the EPS_ECU 24 is input to the vehicle behavior control ECU 12.

  The wheel speed sensor 20 functions as vehicle speed detection means for detecting the speed of the vehicle on which the vehicle behavior control device 10 is mounted. The wheel speed sensor 20 is provided on each of the right front wheel, the left front wheel, the right rear wheel, and the left rear wheel of the vehicle, and detects the wheel speed Vw of each wheel. The wheel speed Vw is input to the vehicle behavior control ECU 12. In addition to or instead of the wheel speed sensor 20, a vehicle speed sensor that detects the vehicle speed itself may be provided.

  The vehicle behavior control ECU 12 includes a front wheel lateral force estimation unit 28, a front axle weight estimation unit 30, a stability factor determination unit 32, a target yaw rate calculation unit 34, a side slip suppression control unit 36, and a map data storage unit 38. Is provided.

  The front wheel lateral force estimation unit 28 estimates the front wheel lateral force Fy based on the steering torque MT, the assist torque AT, and the steering angle δ.

The front axle weight estimation unit 30 estimates the front axle weight Fw of the vehicle based on the front wheel lateral force Fy estimated by the front wheel lateral force estimation unit 28 and the vehicle lateral acceleration Gy detected by the vehicle lateral acceleration sensor 18. To do. The formula for calculating the front shaft weight Fw is shown below.
Fw = Fy / Gy

  The stability factor determination unit 32 determines a stability factor Kh representing the turning characteristics of the vehicle based on the front axle weight Fw estimated by the front axle weight estimation unit 30. When determining the stability factor Kh, the stability factor determination unit 32 refers to the map data stored in the map data storage unit 38. This map data defines the relationship between the front axle weight Fw and the stability factor Kh. FIG. 2 shows an example of map data that defines the relationship between the front axle weight Fw and the stability factor Kh. The map data as shown in FIG. 2 is set in advance by experiment, simulation, or the like for each vehicle type on which the vehicle behavior control device 10 is mounted.

  The target yaw rate calculation unit 34 acquires from the wheel speed sensor 20 wheel speed Vw, the steering angle δ acquired from the steering angle sensor 16, the vehicle lateral acceleration Gy acquired from the vehicle lateral acceleration sensor 18, and the stability factor determination unit 32. The target yaw rate γt of the vehicle is calculated based on the stability factor Kh.

  The side slip suppression control unit 36 compares the target yaw rate γt acquired from the target yaw rate calculation unit 34 with the actual yaw rate γr acquired from the yaw rate sensor 22, and issues an instruction to the brake ECU 24 and the engine ECU 26 based on the comparison result. The braking force and driving force are controlled. The brake ECU 24 adjusts the hydraulic pressure of a wheel cylinder (not shown) of a disc brake provided on each wheel by controlling an electromagnetic valve, a pump, etc. (not shown) of the brake hydraulic circuit. The engine ECU 40 controls the output of an engine (not shown).

  For example, when the actual yaw rate γr is smaller than the target yaw rate γt, the skid suppression control unit 36 determines that the front wheels of the vehicle tend to skid, instructs the engine ECU 26 to suppress the output of the engine, and instructs the brake ECU 24. By braking each wheel and reducing the lateral force, the tendency of skidding on the front wheels is suppressed. On the other hand, when the actual yaw rate γr is larger than the target yaw rate γt, the skid control unit 36 determines that the rear wheels of the vehicle tend to skid, and brakes the front wheels and rear wheels outside the turn according to the degree of the tendency. In addition, a moment is generated outwardly of the vehicle to suppress the tendency of skidding on the rear wheels.

  FIG. 3 is a flowchart for explaining the control of the vehicle behavior control apparatus 10 according to the present embodiment. The control shown in the flowchart of FIG. 3 is executed when the ignition switch is turned on.

  When the ignition switch is turned on, the stability factor determination unit 32 sets the stability factor Kh to Kh1 (fixed value) (S10). This Kh1 may be a stability factor when the vehicle is in a lightly loaded state, for example.

Next, the skid suppression control unit 36 determines whether the vehicle is in a stable turning traveling state (S12). Specifically, the following conditions (1) to (5) are determined, and it is determined whether or not the vehicle is in a stable turning traveling state based on the determination result.
(1) Driving on good roads (whether driving on dry asphalt roads)
(2) Turning without skidding (whether vehicle lateral acceleration Gy is 0.1 to 0.3 G)
(3) Vehicle longitudinal acceleration is small (whether the longitudinal load is small)
(4) Small steering angular velocity and small steering torque MT fluctuation (whether stable turning state or not)
(5) Vehicle speed of 30 km / h or more (whether the steering wheel is stationary)
Said condition (1) can be determined based on the fluctuation | variation of the wheel speed Vw from the wheel speed sensor 20, for example. Condition (3) can be determined based on information from a vehicle longitudinal acceleration sensor (not shown). Condition (4) can be determined based on information from the steering angle sensor 16 and the steering torque sensor 14. The condition (4) can be determined based on information from the wheel speed sensor 20 and / or the vehicle speed sensor (not shown).

  The side-slip suppression control unit 36 determines that the vehicle is in a stable turning traveling state when all of the above conditions (1) to (5) are satisfied (Y in S12). Then, steps S14 to S22 described later are skipped.

  On the other hand, if any one of the above conditions (1) to (5) is not satisfied, the skid control unit 36 determines that the vehicle is not in a stable turning state (N in S12). In this case, the front wheel lateral force estimating unit 28 estimates the front wheel lateral force Fy based on the steering torque MT, the assist torque AT, and the steering angle δ (S14).

  Subsequently, the front axle weight estimation unit 30 determines the front axle weight of the vehicle based on the front wheel lateral force Fy estimated by the front wheel lateral force estimation unit 28 and the vehicle lateral acceleration Gy detected by the vehicle lateral acceleration sensor 18. Fw is estimated (S16).

  Subsequently, the stability factor determination unit 32 determines a stability factor Kh representing the turning characteristics of the vehicle based on the front axle weight Fw estimated by the front axle weight estimation unit 30 (S18).

  After determining the stability factor Kh, the target yaw rate calculator 34 calculates the target yaw rate γt using the stability factor Kh (S20). Then, the skid control unit 36 compares the target yaw rate γt with the actual yaw rate γr, and performs the skid control of the vehicle (S22).

  The loop of S12 to S22 is repeated until a predetermined stop condition is satisfied. The stop condition is, for example, that an ignition switch is turned off.

  The vehicle behavior control device 10 according to this embodiment has been described above. In the vehicle behavior control apparatus 10 according to the present embodiment, based on the front wheel lateral force Fy estimated based on the steering torque MT, the assist torque AT, and the steering angle δ, and the vehicle lateral acceleration Gy detected by the vehicle lateral acceleration sensor 18. Thus, the front axle weight Fw of the vehicle is estimated. Then, the stability factor Kh used to calculate the target yaw rate γt is determined with reference to the map data that defines the relationship between the front axle weight Fw and the stability factor Kh. As a result, an appropriate stability factor Kh corresponding to the front axle weight Fw can be determined, so that it is possible to perform appropriate skid suppression control according to the loaded state and the lightly loaded state.

  In the vehicle behavior control apparatus 10 according to the present embodiment, it is not necessary to provide a load meter for detecting the load of the vehicle on the vehicle, and sensor information from a system such as EPS already installed in an existing vehicle is used. Since the front wheel lateral force Fw is estimated, it is possible to perform appropriate skid suppression control while suppressing an increase in cost.

  The present invention has been described above based on the embodiment. It should be understood by those skilled in the art that these embodiments are exemplifications, and that various modifications can be made to the combination of each component and each processing process, and such modifications are also within the scope of the present invention.

  DESCRIPTION OF SYMBOLS 10 Vehicle behavior control apparatus, 12 Vehicle behavior control ECU, 14 Steering torque sensor, 16 Steering angle sensor, 18 Vehicle lateral acceleration sensor, 20 Wheel speed sensor, 22 Yaw rate sensor, 24 EPS_ECU, 28 Front wheel lateral force estimation part, 30 Front shaft A weight estimation unit, 32 a stability factor determination unit, 34 a target yaw rate calculation unit, 36 a skid suppression control unit, and 38 a map data storage unit.

Claims (3)

Steering torque detection means for detecting steering torque;
Assist torque generating means for generating assist torque;
Steering angle detection means for detecting the steering angle;
Front wheel lateral force estimating means for estimating front wheel lateral force based on steering torque, assist torque and steering angle;
Vehicle lateral acceleration detection means for detecting vehicle lateral acceleration;
Front axle weight estimating means for estimating a front axle weight based on a front wheel lateral force and a vehicle lateral acceleration;
A stability factor determining means for determining a stability factor representing a turning characteristic of the vehicle based on a front axle weight;
Side slip suppression control means for performing side slip suppression control of a vehicle using a stability factor;
A vehicle behavior control device comprising: A storage means for storing the relationship between the front axle weight and the stability factor;
2. The vehicle behavior control device according to claim 1, wherein the stability factor determination unit determines a stability factor with reference to a relationship stored in the storage unit. A vehicle state estimation device for estimating a front axle weight of a vehicle,
Steering torque detection means for detecting steering torque;
Assist torque generating means for generating assist torque;
Steering angle detection means for detecting the steering angle;
Front wheel lateral force estimating means for estimating front wheel lateral force based on steering torque, assist torque and steering angle;
Vehicle lateral acceleration detection means for detecting vehicle lateral acceleration;
Front axle weight estimating means for estimating a front axle weight based on a front wheel lateral force and a vehicle lateral acceleration;
A vehicle state estimation device comprising:

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