JP5910265B2 - Vehicle control device - Google Patents

Description

  The present invention relates to a vehicle control apparatus that estimates a state of a vehicle and controls the vehicle.

  Conventionally, in order to stabilize the behavior of a traveling vehicle, a vehicle control apparatus that controls the vehicle based on the traveling state of the vehicle is widely known. For example, there are known vehicle behavior stabilization systems such as a system that controls rotation of a tire to prevent idling, an antilock brake system that controls braking of the vehicle, and a system that stabilizes the posture of the vehicle during turning. In the vehicle behavior stabilization system, the side slip amount of the vehicle is used as the vehicle state quantity.

  Patent Document 1 discloses a slip angle estimation device that estimates a slip angle that is a state quantity of a vehicle. This slip angle estimation device uses a G sensor to detect a slip angle estimated based on a vehicle speed detected from a vehicle speed sensor, a driver's steering angle detected from a steering angle sensor, and a vehicle yaw rate detected from a yaw rate sensor. A technique for compensating based on the actual lateral acceleration is disclosed.

JP 2011-235875 A

  By the way, in a vehicle with a high vehicle height such as a wagon car or a sports multi-purpose vehicle, the position of the center of gravity is higher than that of a general passenger car, and the influence of the roll at the center of gravity increases when the vehicle shakes in the roll direction. The yaw rate sensor and the G sensor are provided near the position of the center of gravity of the vehicle, and the detection result of the G sensor is more greatly affected by the roll than the yaw rate sensor.

  In the technique of Patent Document 1, there is a possibility that a phase shift may occur between the detection result of the yaw rate sensor and the detection result of the G sensor when the vehicle is greatly shaken in the roll direction, and is estimated based on the detection result of the yaw rate sensor. If the slip angle is compensated based on the actual lateral acceleration detected by the G sensor, the phase shift amount is also compensated, and the slip angle estimation accuracy may be lowered.

  This invention is made | formed in view of such a condition, The objective is to provide the vehicle control apparatus which can estimate the state of a vehicle accurately.

In order to solve the above problems, a vehicle control device according to an aspect of the present invention includes a vehicle speed detection unit that calculates a vehicle speed, a yaw rate detection unit that calculates a yaw rate of the vehicle, and a steering force that detects a steering force of a front wheel. Detection means, lateral force calculation means for calculating lateral force applied to the front wheel in the vehicle width direction based on the steering force, and lateral acceleration estimation for estimating lateral acceleration in the vehicle width direction of the vehicle based on the lateral force Means, lateral acceleration detecting means for detecting lateral lateral acceleration generated in the vehicle, and side slip amount estimating means for estimating a side slip amount in the vehicle width direction of the rear wheel based on the vehicle speed, yaw rate and lateral acceleration. The side slip amount estimating means calculates a side slip amount of the rear wheel based on the lateral acceleration detected by the side acceleration detecting means when a predetermined condition is satisfied, and when the predetermined condition is not satisfied, Estimated Calculating the sideslip amount of the rear wheels based on the lateral acceleration a.

According to this aspect, it is possible to accurately estimate the amount of skid of the vehicle. Further, the lateral acceleration in the vehicle width direction of the vehicle can be estimated from the turning force applied to the front wheels.

The skid amount estimating means may estimate the skid amount of the rear wheel based on a comparison between the lateral acceleration estimated by the lateral acceleration estimating means and the lateral acceleration of the vehicle calculated from the yaw rate and the vehicle speed. As a result, one lateral acceleration is estimated from the steering force, and the other lateral acceleration is calculated from the yaw rate and the vehicle speed. it can. The side slip amount estimation means calculates the side slip amount of the rear wheel based on the lateral acceleration estimated by the side acceleration estimation means and executes the vehicle behavior stabilization control until execution of the vehicle behavior stabilization control is started. In the meantime, the side slip amount of the rear wheel may be calculated based on the lateral acceleration detected by the lateral acceleration detecting means.

  According to the present invention, it is possible to accurately estimate the state of the vehicle.

It is a figure which shows roughly the vehicle by which a vehicle control apparatus is mounted. It is explanatory drawing for demonstrating the roll of a vehicle. It is a figure for demonstrating calculation of the amount of skid of the rear wheel in the vehicle with a high vehicle height in a comparison technique. It is a figure which shows the functional block of ECU. It is a figure which shows the result of having estimated the side slip amount of the rear wheel which concerns on embodiment.

  FIG. 1 is a diagram schematically showing a vehicle 1 on which a vehicle control device 2 is mounted. The vehicle control device 2 includes a steering handle 10, a steering input shaft 11, a steering output shaft 12, a steering angle sensor 14, a yaw rate sensor 16, a G sensor 18, an ECU 20, an actuator 21, a motor 22, a vehicle speed sensor 30, and a front wheel steering. A unit 40 is provided.

  The steering handle 10 that is rotated by the driver is fixed to the upper end of the steering input shaft 11, and the lower end of the steering input shaft 11 is connected to the FR actuator 21. The FR actuator 21 may be a transmission ratio variable actuator, and includes an FR motor 22 that is an electric motor and a speed reducer, and is connected to the speed reducer with respect to the rotation amount (or rotation angle) of the steering input shaft 11. The rotation amount (or rotation angle) of the steering output shaft 12 is changed as appropriate.

  The FR motor 22 has a motor housing that is integrally connected to the steering input shaft 11, and rotates integrally in accordance with a turning operation of the steering handle 10 by the driver. The drive shaft of the FR motor 22 is connected to a speed reducer, and the rotational force of the FR motor 22 is transmitted to the speed reducer via the drive shaft. The reduction gear is configured by a predetermined gear mechanism, and the turning output shaft 12 is connected to the gear mechanism at the upper end. Thus, when the rotational force of the FR motor 22 is transmitted through the drive shaft, the speed reducer decelerates the rotation of the drive shaft by the gear mechanism and transmits it to the steered output shaft 12. Therefore, the FR actuator 21 connects the steering input shaft 11 and the steered output shaft 12 via the drive shaft of the FR motor 22 so as to be relatively rotatable.

  The vehicle control device 2 also includes a front wheel steering unit 40 that is a front wheel side steering mechanism connected to the lower end of the steering output shaft 12. The front wheel steering unit 40 is, for example, a gear unit adopting a rack and pinion type, and the rotation of the pinion gear integrally assembled to the lower end of the steering output shaft 12 is transmitted to the rack bar. Yes. Further, the front wheel steering unit 40 has an EPS (Electric Power Steering) motor 24 that is an electric motor for reducing a steering force (more specifically, a steering torque) input to the steering handle 10 by the driver. The torque (so-called assist force) generated by the EPS motor is transmitted to the rack bar. The assist force of the EPS motor is detected by a torque sensor 25 provided on the EPS motor. The steering force and the assist force are collectively referred to as a steering force, and a steering force is applied to the front wheel steering unit 40 to steer the front wheels.

  With this configuration, the rotational force of the steering output shaft 12 is transmitted to the rack bar via the pinion gear, and the assist force of the EPS motor is transmitted to the rack bar. As a result, the rack bar is displaced in the axial direction by the rotational force from the pinion gear and the assist force of the EPS motor, and the left and right front wheels FW1, FW2 connected to both ends of the rack bar are steered left and right. . The vehicle control device 2 may steer the left and right rear wheels RW1 and RW2 in relation to the steering of the left and right front wheels FW1 and FW2.

  The vehicle speed sensor 30 detects the amount of rotation of the axle per time that can be converted into the vehicle speed, or the amount of rotation of the differential gear per time, and transmits the detection result to the ECU 20. The yaw rate sensor 16 detects the yaw rate generated in the vehicle 1 and transmits the detection result to the ECU 20. The G sensor 18 detects the lateral acceleration and the longitudinal acceleration generated in the vehicle 1, and transmits the detection result to the ECU 20. The lateral direction refers to the vehicle width direction along the axle.

  In the vehicle control device 2, an ECU (electronic control unit) 20 controls the operation of the FR actuator 21, specifically, controls the rotation of the FR motor 22 to give a steering torque to the front wheels FW 1 and FW 2. . The ECU is configured as a microprocessor including a CPU, and includes a ROM for storing various programs, a RAM for temporarily storing data, an input / output port, a communication port, and the like in addition to the CPU.

  FIG. 2 is an explanatory diagram for explaining the roll of the vehicle. FIG. 2A shows a roll of a general passenger car 1a, and FIG. 2B shows a roll of a vehicle 1b having a high vehicle height.

  A vehicle 1b such as a one-box vehicle or a wagon vehicle shown in FIG. 2B has a higher vehicle height than a general passenger car 1a, and the center of gravity position 4b of the vehicle 1b also increases. Therefore, when driving the vehicle 1b, a larger roll is generated at the center of gravity position 4b than at the center of gravity position 4a of the passenger car 1a.

  Here, the yaw rate sensor 16 and the G sensor 18 are collectively provided near the gravity center position 4b. If the G sensor 18 is provided at a low position, the influence of the roll can be suppressed. However, if the G sensor 18 is provided outside the vehicle, the durability becomes low, so it is necessary to provide at least the inside of the vehicle. is there. Therefore, compared with the general passenger car 1a, in the vehicle 1b with a high vehicle height, the position where the G sensor 18 is provided becomes higher and is greatly affected by the roll. For example, the yaw rate sensor 16 and the G sensor 18 are provided below the parking brake and the side box between the driver seat and the passenger seat.

  FIG. 3 is a diagram for explaining the calculation of the amount of skid of the rear wheels in the vehicle 1b having a high vehicle height according to the comparative technique. The comparison technique is a technique for comparing with the embodiment. The vertical axis in FIG. 3 is the lateral acceleration, and the horizontal axis is time. 3 shows the first lateral acceleration 42 of the vehicle 1b calculated by the G sensor 18, the second lateral acceleration 44 of the vehicle 1b calculated by the yaw rate sensor 16 and the vehicle speed sensor 30, and the rear wheel calculated based on them. The side slip amount 46 is shown. FIG. 3 shows a case where the vehicle 1b is traveling straight in a state where a roll is generated in the vehicle 1b. The side slip amount indicates the degree of slip of the vehicle in the vehicle width direction, and is zero if the vehicle is gripping.

The side slip amount 46 of the rear wheel was calculated by the following equation (1) in the comparative technique.
Side slip amount of rear wheel = lateral acceleration of G sensor− (yaw rate × vehicle speed) (1)
The term (yaw rate × vehicle speed) in the equation (1) is the second lateral acceleration 44 of the vehicle 1 b calculated from the detection results of the yaw rate sensor 16 and the vehicle speed sensor 30.

  The G sensor 18 greatly influenced by the roll tends to be delayed in phase as compared with the output of the yaw rate sensor 16, and even if the almost same amount of side slip is calculated from each sensor, the position of the G sensor 18 and the yaw rate sensor 16 is the same. The side slip amount 46 of the rear wheel may be calculated to be large due to the phase difference.

  For example, if the side slip amount 46 of the vehicle 1b is larger than a predetermined value, the vehicle state control means executes control for suppressing the side slip of the vehicle 1b so that the behavior of the vehicle 1b is stabilized. For this reason, in the vehicle 1b having a high vehicle height, the vehicle behavior stabilization control may be started due to the influence of the roll even if the rear wheel does not skid. On the other hand, in order to suppress the early operation of the vehicle behavior stabilization control, the start of the vehicle behavior stabilization control will be delayed when processing such as increasing the dead zone of the side slip amount until the vehicle behavior stabilization control is started. was there.

  Therefore, the vehicle control apparatus 2 according to the embodiment estimates the lateral slip of the vehicle by estimating the lateral acceleration of the vehicle based on the steering force of the front wheels instead of the G sensor 18. Thereby, it is possible to accurately estimate the amount of skid without being affected by the roll.

  FIG. 4 is a diagram illustrating functional blocks of the ECU 20. The ECU 20 includes an information receiving unit 50, a vehicle speed calculation unit 52, a yaw rate calculation unit 54, a turning force calculation unit 56, a lateral force calculation unit 58, a lateral acceleration estimation unit 59, a side slip amount estimation unit 60, and a vehicle state control unit 62. .

  The information receiving unit 50 receives a signal indicating the detection result from each sensor provided in the vehicle 1 and sends it to the vehicle speed calculating unit 52, the yaw rate calculating unit 54, and the turning force calculating unit 56. The vehicle speed calculation unit 52 calculates the vehicle speed of the vehicle based on the detection result of the vehicle speed sensor 30.

  The yaw rate calculation unit 54 calculates the yaw rate of the vehicle based on the detection result of the yaw rate sensor 16. The turning force calculation unit 56 calculates the turning torque of the front wheels based on the detection result of the steering angle sensor 14 and the detection result of the torque sensor 25. The turning force calculation unit 56 calculates the turning force applied to the front wheels by the steering force by the driver and the assist force by EPS.

  The lateral force calculation unit 58 calculates the lateral force applied to the front wheels in the vehicle width direction based on the steering force calculated by the steering force calculation unit 56. The lateral force calculation unit 58 calculates the lateral force of the front wheels from the steering force based on the characteristics of the front wheel steering unit 40 such as the radius of the pinion gear.

  The lateral acceleration estimating unit 59 estimates the lateral acceleration applied to the vehicle 1 in the vehicle width direction based on the lateral force calculated by the lateral force calculating unit 58 and the yaw rate calculated by the yaw rate calculating unit 54. That is, the lateral acceleration estimation unit 59 estimates the lateral acceleration of the entire vehicle 1 based on the lateral force of the front wheels that does not include the detected value of the rear wheel state.

  The side slip amount estimation unit 60 receives the vehicle speed, yaw rate, and lateral acceleration from the vehicle speed calculation unit 52, the yaw rate calculation unit 54, and the lateral acceleration estimation unit 59, respectively, and moves in the vehicle width direction of the rear wheels based on the vehicle speed, yaw rate, and lateral acceleration. Estimate the amount of skidding. Since the lateral acceleration calculated by the lateral acceleration estimating unit 59 is based on the steering force of the front wheels, the skid amount estimating unit 60 determines the rear wheel based on the vehicle speed, the yaw rate of the vehicle 1, and the steering force of the front wheels. The amount of skidding is estimated.

The skid amount estimating unit 60 calculates the skid amount of the rear wheel by the following equation (2).
Rear wheel side slip amount = lateral acceleration from steering force of front wheel− (yaw rate × vehicle speed) (2)
The term (yaw rate × vehicle speed) is the lateral acceleration of the vehicle 1 calculated from the detection results of the yaw rate sensor 16 and the vehicle speed sensor 30, and is not an actual value detected by the G sensor but an estimated value.

  The side slip amount estimating method of the side slip amount estimating unit 60 is different from the equation (1) in that the side acceleration estimated based on the steering force of the front wheels is used without using the detection result of the G sensor 18. As a result, the side slip amount of the rear wheel can be estimated based on the lateral acceleration calculated by a method other than the G sensor 18 influenced by the roll of the vehicle 1.

  FIG. 5 is a diagram illustrating a result of estimating the side slip amount of the rear wheel according to the embodiment. The vertical axis in FIG. 5 is the lateral acceleration, and the horizontal axis is the time. FIG. 5 shows the first lateral acceleration 70 of the vehicle 1 estimated based on the steering force, the second lateral acceleration 72 of the vehicle 1 calculated by the yaw rate sensor 16 and the vehicle speed sensor 30, and the estimation based on them. The rear wheel skid amount 74 is shown.

  In FIG. 5, the skid amount 74 is calculated under the same conditions as those shown in FIG. That is, the skid amount 74 is calculated in a state where a roll is generated in the vehicle 1 having a high vehicle height. The first lateral acceleration 70 calculated by the lateral acceleration estimator 59 is calculated based on the steering force of the front wheels, so that the influence of the vehicle roll is small. Further, the second lateral acceleration 72 of the vehicle 1 calculated from the detection results of the yaw rate sensor 16 and the vehicle speed sensor 30 is also less influenced by the roll of the vehicle 1.

  Accordingly, it is possible to suppress the shift of the phase of the lateral acceleration due to the influence of the roll, and to increase the estimation accuracy of the side slip amount 74. By executing the vehicle behavior stabilization control based on the side slip amount 74, the control feeling can be improved.

  In the embodiment, the aspect in which the side slip amount of the rear wheel is estimated using the lateral acceleration estimated from the steering force and used for the vehicle behavior stabilization control is described. However, the present invention is not limited to this aspect. The lateral acceleration and the lateral acceleration estimated from the steering force may be properly used. That is, the side slip amount calculated by the equation (1) and the side slip amount calculated by the equation (2) are properly used depending on the case.

  The side slip amount estimating unit 60 calculates the side slip amount of the rear wheel based on the lateral acceleration calculated from the G sensor 18 when a predetermined condition is satisfied, and the side slip estimated from the steering force when the predetermined condition is not satisfied. The side slip amount of the rear wheel is calculated based on the acceleration. The predetermined condition may be whether or not the vehicle behavior stabilization control is executed.

  That is, when it is determined to start the vehicle behavior stabilization control, the G sensor 18 is used during the vehicle behavior stabilization control using the side slip amount calculated based on the lateral acceleration estimated from the steering force of the front wheels. The side slip amount calculated based on the lateral acceleration calculated from the above is used. As a result, the lateral acceleration detected by the G sensor 18 can be used instead of the estimated value when the vehicle behavior stabilization control is being executed while the vehicle behavior stabilization control is being started at an appropriate timing. It is possible to improve the control performance to suppress the side slip.

  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.

  In the embodiment, the vehicle speed sensor 30 is a sensor that detects the rotational speed of an axle or a differential gear, but is not limited thereto. For example, it may be a sensor that is provided on each wheel and detects the rotational speed of the wheel.

  Further, a steering torque detection sensor that detects a steering force that combines the steering force and the assist force may be provided in the front wheel steering unit 40.

  DESCRIPTION OF SYMBOLS 1 Vehicle, 2 Vehicle control apparatus, 4 Center of gravity, 10 Steering handle, 11 Steering input shaft, 12 Steering output shaft, 14 Steering angle sensor, 16 Yaw rate sensor, 18 G sensor, 20 ECU, 21 Actuator, 22 FR motor, 24 EPS motor, 25 torque sensor, 30 vehicle speed sensor, 40 front wheel steering unit, 50 information receiving unit, 52 vehicle speed calculation unit, 54 yaw rate calculation unit, 56 steering force calculation unit, 58 lateral force calculation unit, 59 lateral acceleration estimation unit 60 Side slip amount estimation part, 62 Vehicle state control part.

Claims (2)

Vehicle speed detecting means for calculating the vehicle speed;
Yaw rate detection means for calculating the yaw rate of the vehicle;
A turning force detecting means for detecting a turning force applied to the front wheels;
Lateral force calculation means for calculating lateral force applied to the front wheels in the vehicle width direction based on the steering force;
Lateral acceleration estimating means for estimating lateral acceleration in the vehicle width direction of the vehicle based on the lateral force;
Lateral acceleration detecting means for detecting lateral lateral acceleration generated in the vehicle;
A side slip amount estimating means for estimating a side slip amount in the vehicle width direction of the rear wheel based on the vehicle speed, the yaw rate, and the side acceleration,
The side slip amount estimating means calculates the side slip amount of the rear wheel based on the lateral acceleration estimated by the side acceleration estimating means until the execution of the vehicle behavior stabilization control, and performs the vehicle behavior stabilization control. During execution , the vehicle control apparatus is characterized in that the amount of side slip of the rear wheel is calculated based on the lateral acceleration detected by the lateral acceleration detecting means.   The side slip amount estimation means estimates the side slip amount of the rear wheel based on a comparison between the lateral acceleration estimated by the lateral acceleration estimation means and the lateral acceleration of the vehicle calculated from the yaw rate and the vehicle speed. The vehicle control device according to claim 1.

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