JP2017159717A - Vehicle forward/backward speed estimation device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a vehicle forward/backward speed estimation device which can accurately estimate a vehicle forward/backward speed for a vehicle comprising steering wheels which are driven wheels, and driving wheels, despite a vehicle travel condition.SOLUTION: Vehicle speed selection means 29 selects and outputs a forward/backward speed of a vehicle estimated by first vehicle speed estimation means 27 in an ordinary travel condition. Since a standard side-slip angle can be accurately estimated in the ordinary travel condition, selecting and outputting the vehicle forward/backward speed estimated by the first vehicle speed estimation means 27 can accurately estimate the vehicle forward/backward speed. When the vehicle travel condition is determined to be in a predetermined limit travel condition by travel condition determination means 26, the vehicle speed selection means 29 selects and outputs an estimated vehicle forward/backward speed estimated by second vehicle speed estimation means 28.SELECTED DRAWING: Figure 3

Description

  The present invention relates to a vehicle longitudinal speed estimation apparatus, and more particularly to a vehicle longitudinal speed estimation apparatus in which drive wheels and steered wheels are arranged at different positions.

  In order to prevent idling of the wheel, for example, to perform traction control, the vehicle speed at the position of the drive wheel is required. In the case of a vehicle in which the drive wheel and the steered wheel are arranged at different positions, the drive wheel and the vehicle are arranged so that a plane perpendicular to the rotation axis of the drive wheel and the longitudinal direction of the vehicle body are parallel to each other. For this reason, the vehicle speed at the position of the drive wheel can be calculated from the longitudinal speed and the yaw rate of the vehicle. The longitudinal speed of the vehicle can be accurately estimated by using the wheel rotational speed of the driven wheel. Here, when the skid angle generated in the vehicle is large, it is necessary to correct the influence of the skid angle of the vehicle.

For example, a technique has been proposed in which a side slip angular velocity is obtained using a tangential acceleration and a normal direction acceleration of a turning circle, and a yaw rate, and the side slip angle is estimated by integrating the side slip angular velocity (Patent Document 1). The estimated longitudinal slip angle is used to estimate the longitudinal speed of the turning vehicle.
By the way, regarding the estimation of the skid angle, for example, a technique for estimating the skid angle from a vehicle model using the steering wheel angle and the vehicle speed as input variables has been proposed (Patent Document 2). The longitudinal speed of the vehicle body can be estimated from the estimated side slip angle and wheel rotational speed.

Japanese Patent Laid-Open No. 10-175537 JP 62-83247 A

  In Patent Document 1, the side slip angular velocity is obtained using the tangential acceleration and normal acceleration of the turning circle, and the yaw rate, and the side slip angle is estimated by integrating the side slip angular velocity. However, errors (drift) are likely to accumulate in the integral calculation. Therefore, if the integration calculation for a long time is performed, the estimation accuracy of the skid angle is likely to deteriorate, and therefore the vehicle longitudinal speed may not be estimated accurately.

  In Patent Document 2, a side slip angle is estimated from a vehicle model. As shown in FIG. 6, in a region where the lateral force (cornering force) that can be generated by the tire has a linear relationship with respect to the skid angle occurring in the tire (hereinafter referred to as “the linear region of the tire”), it is good. The side slip angle can be estimated with high accuracy, but in the region where the side force that can be generated by the tire has a non-linear relationship with the side slip angle that occurs in the tire (hereinafter referred to as the “tire non-linear region”), the side slip angle is estimated. Accuracy deteriorates. In this case, the longitudinal speed of the vehicle cannot be estimated accurately.

  As another method, it is conceivable to estimate the longitudinal speed of the vehicle from the integral calculation of the longitudinal acceleration. However, an error (drift) is easily accumulated in the integral calculation, and the vehicle longitudinal speed cannot be accurately estimated.

  An object of the present invention is to provide a vehicle longitudinal speed estimation device capable of accurately estimating the longitudinal speed of a vehicle in a vehicle including steered wheels that are driven wheels and drive wheels, regardless of the traveling state of the vehicle. It is to be.

A vehicle longitudinal speed estimation apparatus according to the present invention is a longitudinal speed estimation apparatus 10 that estimates longitudinal speed in a vehicle including left and right steered wheels 3 that are driven wheels and left and right drive wheels 2.
A pair of wheel rotation speed measuring means 14 for measuring the wheel rotation speeds of the left and right steered wheels 3;
Handle angle measuring means 15 for measuring the handle angle of the vehicle;
Yaw rate measuring means 16 for measuring the yaw rate of the vehicle;
Longitudinal acceleration measuring means 17 for measuring longitudinal acceleration of the vehicle;
Traveling state determination means 26 for determining whether the traveling state of the vehicle is a predetermined limit traveling state;
A vehicle for estimating a standard side slip angle by a vehicle model using the wheel rotational speed of the left and right steered wheels 3 measured by the wheel rotational speed measuring means 14 and the steering wheel angle measured by the steering wheel angle measuring means 15 as inputs. Model response calculation means 25;
The vehicle front-rear speed is estimated using the wheel rotational speed of the left and right steered wheels 3, the steering wheel angle, the yaw rate measured by the yaw rate measuring means 16, and the reference side slip angle estimated by the vehicle model response calculating means 25. First vehicle speed estimating means 27 for
A second vehicle speed estimating means 28 for estimating the longitudinal speed of the vehicle by integrating the longitudinal acceleration measured by the longitudinal acceleration measuring means 17;
Before and after the vehicle estimated by either one of the first vehicle speed estimating means 27 or the second vehicle speed estimating means 28 in accordance with a predetermined rule based on the traveling state of the vehicle determined by the traveling state determining means 26. Vehicle speed selection means 29 for selecting the speed,
The vehicle speed selection means 29 selects and outputs the vehicle front-rear speed estimated by the first vehicle speed estimation means 27 under normal conditions as the determined rule, and the travel state determination means 26 travels the vehicle. If it is determined that the vehicle is in a limited running state, the vehicle longitudinal speed estimated by the second vehicle speed estimating means 28 is selected and output.
The determined rule is a rule arbitrarily determined by design or the like, and is determined by seeking an appropriate rule by one or both of testing and simulation, for example.
The traveling state of the vehicle includes a normal traveling state where the vehicle is traveling in a linear region of the tire and a limit traveling state where the vehicle is traveling in a nonlinear region of the tire.
The determined limit driving state is a driving state arbitrarily determined by design or the like, and is determined by determining an appropriate non-linear region of the tire by, for example, one or both of a test and a simulation.
In this specification, “wheel rotation speed” is synonymous with the number of wheel rotations per unit time.

According to this configuration, the vehicle model response calculation means 25 estimates the reference side slip angle from the vehicle model, using the wheel rotation speeds and the steering wheel angles of the left and right steered wheels 3 as inputs.
As the vehicle model, for example, a planar two-degree-of-freedom model (common name: a planar two-wheel model) is used, but is not limited to this planar two-wheel model.

  The first vehicle speed estimation means 27 estimates the vehicle front-rear speed using the wheel rotation speed, the steering wheel angle, the yaw rate, and the standard skid angle of the left and right steered wheels 3. The vehicle speed selection means 29 selects the vehicle front-rear speed estimated by the first vehicle speed estimation means 27 in a normal state (for example, in a state where the vehicle is traveling in a linear region of the tire (hereinafter referred to as “normal traveling state”). Since the standard side slip angle can be estimated with good accuracy in the normal running state, the vehicle longitudinal speed estimated by the first vehicle speed estimating means 27 as described above is selected and output accurately. The longitudinal speed of the vehicle can be estimated.

  When the traveling state determining means 26 determines that the traveling state of the vehicle is a determined limit traveling state, the vehicle speed selecting means 29 selects and outputs the vehicle longitudinal speed estimated by the second vehicle speed estimating means 28. To do. In the limit running state, the estimation accuracy of the standard side slip angle is deteriorated, so the first vehicle speed estimation means 27 is not applied and the second vehicle speed estimation means 28 is applied. The second vehicle speed estimating means 28 estimates the longitudinal speed of the vehicle by integrating the longitudinal acceleration measured by the longitudinal acceleration measuring means 17. By limiting the time for the integral calculation to the limit running state in this way, it is possible to prevent the estimation accuracy from deteriorating due to accumulation of error (drift). As described above, the longitudinal speed of the vehicle can be accurately estimated regardless of the traveling state of the vehicle.

A lateral acceleration measuring means 17 for measuring the lateral acceleration of the vehicle, wherein the vehicle model response calculating means 25 receives the wheel rotational speeds and the steering wheel angles of the left and right steered wheels 3 as input, and the reference lateral acceleration or Estimate the normative yaw rate,
The running state determination unit 26 determines whether the deviation between the lateral acceleration measured by the lateral acceleration measurement unit 17 and the standard lateral acceleration is equal to or greater than a threshold value, or the yaw rate measured by the yaw rate measurement unit 16 and the standard yaw rate. When the deviation is equal to or greater than a threshold value, it may be determined that the traveling state of the vehicle is a predetermined limit traveling state.
Each threshold is a value arbitrarily determined by design or the like, and is determined by obtaining an appropriate value by one or both of testing and simulation, for example.

  According to this configuration, when the deviation between the lateral acceleration actually generated in the vehicle and the reference lateral acceleration is greater than or equal to the threshold, or when the deviation between the yaw rate actually generated in the vehicle and the reference yaw rate is greater than or equal to the threshold, It can be considered that the vehicle is in a predetermined limit driving state. By applying the second vehicle speed estimating means 28 in this limit traveling state, the longitudinal speed of the vehicle can be estimated accurately and accurately.

  The vehicle includes a skid prevention control device 21 for preventing the skidding of the vehicle and a braking control device 22 for controlling the braking force of the vehicle, and the traveling state determination means 26 includes the skid prevention control device 21 and the braking control device 22. When either or both of these are operating, it may be determined that the traveling state of the vehicle is a predetermined limit traveling state. By applying the second vehicle speed estimating means 28 in such a limit traveling state, the longitudinal speed of the vehicle can be estimated accurately and accurately.

  When it is determined that the traveling state determination unit 26 is in a predetermined limit traveling state, the vehicle front-rear speed estimated by the first vehicle speed estimation unit 27 immediately before the determination is determined by the second vehicle speed estimation unit 28. It is good also as an initial value of the integral calculation of longitudinal acceleration. In this case, the longitudinal speed of the vehicle estimated by the second vehicle speed estimating means 28 can be estimated with higher accuracy.

  A vehicle longitudinal speed estimation apparatus according to the present invention is a longitudinal speed estimation apparatus that estimates longitudinal speed in a vehicle including left and right steered wheels that are driven wheels and left and right drive wheels, A pair of wheel rotational speed measuring means for measuring the wheel rotational speed, a handle angle measuring means for measuring a steering angle of the vehicle, a yaw rate measuring means for measuring the yaw rate of the vehicle, and a longitudinal acceleration of the vehicle; Longitudinal acceleration measuring means, traveling state determining means for determining whether or not the vehicle traveling state is a predetermined limit traveling state, and wheel rotation of the left and right steered wheels measured by the wheel rotational speed measuring means Vehicle model response calculating means for estimating a reference side slip angle by a vehicle model using the speed and the handle angle measured by the handle angle measuring means as inputs, and the left and right First vehicle speed estimation for estimating the longitudinal speed of the vehicle using the wheel rotation speed of the steered wheel, the steering wheel angle, the yaw rate measured by the yaw rate measuring means, and the reference side slip angle estimated by the vehicle model response calculating means A vehicle speed estimating means for integrating the longitudinal acceleration measured by the longitudinal acceleration measuring means to estimate the longitudinal speed of the vehicle, and based on the traveling state of the vehicle determined by the traveling state determining means Vehicle speed selecting means for selecting a vehicle front-rear speed estimated by one of the first vehicle speed estimating means and the second vehicle speed estimating means according to a predetermined rule. The vehicle speed selection means selects and outputs the vehicle front-rear speed estimated by the first vehicle speed estimation means as a predetermined rule, and outputs the vehicle traveling state by the traveling state determination means. If it is determined that the vehicle is in the limit running state, the vehicle longitudinal speed estimated by the second vehicle speed estimating means is selected and output. For this reason, in a vehicle provided with steered wheels that are driven wheels and drive wheels, the longitudinal speed of the vehicle can be accurately estimated regardless of the traveling state of the vehicle.

1 is a diagram schematically illustrating a system configuration of a vehicle longitudinal speed estimation apparatus according to an embodiment of the present invention in a plan view. It is sectional drawing of the in-wheel motor drive device of the vehicle. It is a block diagram of a control system of the longitudinal speed estimation device. It is a figure which shows the correspondence of each symbol and the position of the vehicle. It is a figure explaining the vehicle model in the front-and-rear speed estimation apparatus. It is a figure which shows the relationship between a side slip angle and side force.

A vehicle longitudinal speed estimation apparatus according to an embodiment of the present invention will be described with reference to FIGS.
FIG. 1 is a diagram schematically illustrating a system configuration of a vehicle longitudinal speed estimation apparatus according to this embodiment in plan view. An electric vehicle 1, which is a vehicle equipped with this longitudinal speed estimation device, is a drive wheel driven by an electric motor 4 having left and right rear wheels 2 as a power source, and left and right front wheels 3 are driven wheels. The left and right front wheels 3 are steered wheels. Each motor 4 can generate a driving force and a braking force, respectively. Each motor 4 constitutes an in-wheel motor drive device IWM.

  As shown in FIG. 2, the in-wheel motor drive device IWM has a motor 4, a speed reducer 6, and a wheel bearing 7, and a part or all of these are arranged in the rear wheel 2. The rotation of the motor 4 is transmitted to the rear wheel 2 via the speed reducer 6 and the wheel bearing 7. A brake rotor 8a constituting the friction brake device 8 is fixed to a flange portion of the hub wheel 7a of the wheel bearing 7, and the brake rotor 8a rotates integrally with the rear wheel 2. The motor 4 is, for example, an embedded magnet type synchronous motor in which a permanent magnet is built in the core portion of the rotor 4a. The motor 4 is a motor in which a radial gap is provided between a stator 4b fixed to the housing 4c and a rotor 4a attached to the rotation output shaft 9.

The control system will be described.
As shown in FIG. 1, the longitudinal speed estimation device 10 is a device that estimates the longitudinal speed of the vehicle. The longitudinal speed estimation device 10 includes an ECU 11 mounted on the vehicle, an inverter device 12 provided for the motor 4, and sensors 13. The ECU 11 includes a computer such as a microcomputer, a program executed by the computer, and various electronic circuits. The ECU 11 and the inverter device 12 are connected by, for example, an in-vehicle communication network such as CAN (Control Area Network).

  The sensors 13 are a pair of wheel rotation speed measuring means 14 for measuring the wheel rotation speeds of the left and right front wheels 3, a handle angle measuring means 15 for measuring the handle angle of the vehicle, and a yaw rate measuring means for measuring the yaw rate of the vehicle. 16 and an acceleration sensor 17 for measuring the longitudinal acceleration and lateral acceleration of the vehicle. The sensors 13 include an accelerator sensor 18 a that detects the operation amount of the accelerator operation means 18 and a brake sensor 19 a that detects the operation amount of the brake operation means 19.

  In this example, the ECU 11 includes a vehicle controller 20, a skid prevention control device (abbreviated as ESC) 21 that controls to prevent the vehicle from slipping, and a braking control device (abbreviated as ABS) 22 that controls the braking force of the vehicle. Have An acceleration command from the accelerator operation means 18 and a deceleration command from the brake operation means 19 are input to the vehicle controller 20, and braking / driving torque corresponding to the difference between the acceleration command and the deceleration command is supplied to the motor of the inverter device 12. This is given to the controller 12a. The motor controller 12a converts to a current command according to the applied braking / driving torque, and gives the current command to the inverter 12b.

As shown in FIG. 3, the vehicle controller 20 includes a vehicle longitudinal speed estimation device main body 23 and a slip ratio control device 24. The front-rear speed estimation device main body 23 includes vehicle model response calculation means 25, travel state determination means 26, first vehicle speed estimation means 27, second vehicle speed estimation means 28, and vehicle speed selection means 29.
The vehicle model response calculation means 25 uses the vehicle model with the wheel rotation speeds of the left and right front wheels 3 measured by the wheel rotation speed measurement means 14 and the vehicle handle angle measured by the handle angle measurement means 15 as inputs. The standard side slip angle β _ref , the standard yaw rate γ _ref , and the standard lateral acceleration A _yref are calculated. A “norm” is attached to the state quantity obtained from the vehicle model. In this example, a planar two-degree-of-freedom model (common name: planar two-wheel model) described later is used as the vehicle model.

The traveling state determination unit 26 determines whether or not the traveling state of the vehicle is a predetermined limit traveling state. As shown in FIG. 6, the traveling state of the vehicle includes a normal traveling state where the vehicle is traveling in the linear region of the tire and a limit traveling state where the vehicle is traveling in the nonlinear region of the tire.
As shown in FIG. 3, the traveling state determination unit 26 determines a deviation (hereinafter referred to as “lateral”) between the _reference lateral acceleration A _yref calculated by the vehicle model response calculation unit 25 and the lateral acceleration A _y actually generated in the vehicle. (Referred to as “acceleration deviation”) ΔA _y is greater than a certain threshold value, or the deviation between the reference yaw rate γ _ref calculated by the vehicle model response calculation means 25 and the yaw rate γ actually generated in the vehicle (hereinafter referred to as “yaw rate deviation”). When Δγ is equal to or larger than a certain threshold value, it is determined that the running state of the vehicle is the limit running state.

The limit running state is a state where the estimation accuracy of the standard side slip angle β _ref estimated using the vehicle model is deteriorated. The lateral acceleration _Ay actually generated in the vehicle is measured by the acceleration sensor 17 which is a lateral acceleration measuring means and a longitudinal acceleration measuring means. The yaw rate γ actually generated in the vehicle is measured by the yaw rate measuring means 16.

Further, the traveling state determination means 26 determines that the traveling state of the vehicle is the limit traveling state when one or both of the skid prevention control device 21 and the braking control device 22 are operating.
When none of the above-mentioned conditions is satisfied, the traveling state determination unit 26 determines that the estimated accuracy of the standard side slip angle β _ref estimated using the vehicle model is good (hereinafter referred to as “normal traveling state”). To do.

The first vehicle speed estimation means 27 uses the following formulas (a1) and (a2) to calculate the vehicle using the wheel rotational speeds ω _FL and ω _FR of the left and right front wheels, the side slip angle β, the handle angle δ _h , and the yaw rate γ. to estimate the longitudinal velocity _{V x} of.

FIG. 4 is a diagram showing the correspondence between each symbol and the position of the vehicle. This will be described with reference to FIGS. 4 and 3 as appropriate.
In equations (a1) and (a2), ω _FL and ω _FR are the wheel rotational speeds of the left and right front wheels 3, β is a side slip angle, δ _h is a steering wheel angle, γ is a yaw rate, δ is an actual steering angle, and _RF is a front wheel. The wheel radius, l _f (FIG. 5) is the distance from the center of gravity P (FIG. 5) to the axle position of the front wheel 3, and n is the steering gear ratio. The side slip angle β is a reference side slip angle estimated from a vehicle model having the vehicle specifications, the handle angle δ _h, and the wheel rotation speeds ω _FL and ω _FR of the steered wheels as input variables.

A vehicle model will be described.
1. Modeling In the four-wheel model ignoring roll motion, it is very complicated to describe the equation of motion because the force and velocity in the front-rear and lateral directions are considered for each wheel.
Therefore, a case where there is no difference in tire characteristics between the left and right wheels and the actual steering angle is small will be considered. Thereby, as shown in FIG. 5, since the influence of the tread can be ignored, the equation of motion can be easily described. FIG. 5 shows a model called a planar two-wheel model.

2. Equation of motion The vehicle weight is m, the actual rudder angle is δ, the distance between the front axle and the center of gravity is l _f , the distance between the rear axle and the center of gravity is l _r , and the center of gravity when the vehicle is viewed from directly above The turning moment (yaw rate) is r, the side slip angles of the front and rear wheels are β _f and β _r , respectively, and the lateral force (cornering force) acting on the front and rear wheels is Y _f and Y _r , respectively.
Here, if the absolute values of the side slip angle and the actual rudder angle of the front and rear wheels are very smaller than “1”, that is, | β _f |, | β _r |, | δ | << 1, these directions are It can be considered that it matches the lateral direction of the vehicle. When the vehicle is viewed from directly above, the formula describing the lateral movement of the vehicle with all angles counterclockwise as positive is as follows.

3. Transfer functions By solving equations (11) and (12) as algebraic equations, β and r transfer functions for steering can be obtained.

When the side slip angle β is estimated from the vehicle model, it can be estimated with good accuracy in the normal running state, but the accuracy is deteriorated in the limit running state.
Therefore, as shown in FIG. 3, when the vehicle is in the limit traveling state, the longitudinal speed of the vehicle is estimated using the second vehicle speed estimating means 28. The second vehicle speed estimation means 28 estimates the vehicle longitudinal speed V _x from the following equation (b1) using the vehicle longitudinal acceleration A _x output from the acceleration sensor 17.

Here, V _xo uses the vehicle longitudinal speed V _x obtained from the equations (a1) and (a2) immediately before the traveling state determination means 26 determines that the traveling state is the limit traveling state. In other words, when the traveling state determination unit 26 determines that the vehicle is in the limit traveling state, the vehicle longitudinal speed V _x estimated by the first vehicle speed estimation unit 27 immediately before the determination is used in the second vehicle speed estimation unit 28. This is the initial value for the integral calculation of longitudinal acceleration. The second vehicle speed estimation means 28 prevents the deterioration of the estimation accuracy due to accumulation of error (drift) by limiting the time for the integral calculation to the limit running state.

Speed selection section 29, the traveling state determining means 26 when it is determined that the normal traveling state, and selects and outputs the longitudinal speed V _x of the vehicle estimated by the first speed estimator 27. Speed selection section 29, the traveling state determining means 26 when it is determined that the maximal running state, selects and outputs the longitudinal speed V _x of the vehicle estimated by the second speed estimator 28.

As shown in FIG. 3 and FIG. 4, the slip ratio control device 24 is, for example, at the position of the driving wheel based on the vehicle longitudinal speed V _x estimated by the longitudinal speed estimation device main body 23 and the yaw rate generated in the vehicle. A vehicle speed _Vdrv is calculated. In FIG. 4, the vehicle speed at the position of the left rear wheel 2 is denoted as V _drvL, and the vehicle speed at the position of the right rear wheel 2 is denoted as V _drvR .

As shown in FIGS. 3 and 4, the slip ratio control device 24 further calculates the slip ratio from the vehicle speed _Vdrv at the position of the drive wheel and the wheel rotation speed of the drive wheel, and sets the slip ratio and the target. From the deviation from the slip ratio, the braking / driving torque generated in the motor of each driving wheel is controlled by feedback control. In making this slip ratio control, by applying the longitudinal velocity estimation device can estimate the longitudinal velocity V _x of accurately vehicle.

  According to the longitudinal speed estimation device 10 described above, the standard side slip angle can be estimated with good accuracy in a so-called normal traveling state in which the vehicle travels in the linear region of the tire. By selecting and outputting the longitudinal speed of the vehicle, the longitudinal speed of the vehicle can be accurately estimated.

  When the traveling state determining unit 26 determines that the traveling state of the vehicle is the limit traveling state, the vehicle speed selecting unit 29 selects and outputs the vehicle longitudinal speed estimated by the second vehicle speed estimating unit 28. In the limit running state, the estimation accuracy of the standard side slip angle is deteriorated, so the first vehicle speed estimation means 27 is not applied and the second vehicle speed estimation means 28 is applied. The second vehicle speed estimation means 28 estimates the longitudinal speed of the vehicle by integrating the longitudinal acceleration measured by the acceleration sensor 17. By limiting the time for the integral calculation to the limit running state in this way, it is possible to prevent the estimation accuracy from deteriorating due to accumulation of error (drift). As described above, the longitudinal speed of the vehicle can be accurately estimated regardless of the traveling state of the vehicle.

Another embodiment will be described.
The in-wheel motor drive device IWM is a so-called direct motor type in which a cycloid reducer, a planetary reducer, a two-axis parallel reducer, and other reducers can be applied. Also good.
In the above-described embodiment, an in-wheel motor type electric vehicle has been described. However, the output of two motors installed in a non-in-wheel motor type vehicle, for example, a vehicle body, is output to the left and right via a drive shaft or the like. This control can also be applied to a so-called two-motor on-board vehicle that transmits to the drive wheels.
The longitudinal speed estimated by the longitudinal speed estimation device of the present embodiment may be used in a traction control device that prevents the wheels from idling.

  As mentioned above, although the form for implementing this invention based on embodiment was demonstrated, embodiment disclosed this time is an illustration and restrictive at no points. The scope of the present invention is defined by the terms of the claims, rather than the description above, and is intended to include any modifications within the scope and meaning equivalent to the terms of the claims.

1 ... Electric car (vehicle)
2 ... Rear wheel (drive wheel)
3 ... Front wheels (driven wheels, steered wheels)
14 ... Wheel rotational speed measuring means 15 ... Handle angle measuring means 16 ... Yaw rate measuring means 17 ... Accelerometer (longitudinal acceleration measuring means, lateral acceleration measuring means)
DESCRIPTION OF SYMBOLS 21 ... Side slip prevention control device 22 ... Braking control device 25 ... Vehicle model response calculation means 26 ... Driving state determination means 27 ... First vehicle speed estimation means 28 ... Second vehicle speed estimation means 29 ... Vehicle speed selection means

Claims (4)

A longitudinal speed estimation device for estimating longitudinal speed in a vehicle having left and right steered wheels that are driven wheels and left and right drive wheels,
A pair of wheel rotation speed measuring means for respectively measuring the wheel rotation speeds of the left and right steered wheels;
A handle angle measuring means for measuring a handle angle of the vehicle;
Yaw rate measuring means for measuring the yaw rate of the vehicle;
Longitudinal acceleration measuring means for measuring longitudinal acceleration of the vehicle;
Traveling state determination means for determining whether the traveling state of the vehicle is a predetermined limit traveling state;
Vehicle model response calculation for estimating a standard skid angle by a vehicle model using the wheel rotational speeds of the left and right steered wheels measured by the wheel rotational speed measuring means and the steering wheel angle measured by the steering wheel angle measuring means as inputs. Means,
A first vehicle front-rear speed is estimated using the wheel rotational speeds of the left and right steered wheels, the steering wheel angle, the yaw rate measured by the yaw rate measuring means, and the reference skid angle estimated by the vehicle model response calculating means. Vehicle speed estimation means,
Second vehicle speed estimation means for integrating the longitudinal acceleration measured by the longitudinal acceleration measurement means to estimate the longitudinal speed of the vehicle;
Based on the traveling state of the vehicle determined by the traveling state determining unit, the vehicle longitudinal speed estimated by one of the first vehicle speed estimating unit and the second vehicle speed estimating unit is selected according to a predetermined rule. Vehicle speed selecting means for
The vehicle speed selection means selects and outputs the vehicle front-rear speed estimated by the first vehicle speed estimation means as a predetermined rule, and outputs the vehicle traveling state by the traveling state determination means. A vehicle longitudinal speed estimation device that selects and outputs the vehicle longitudinal speed estimated by the second vehicle speed estimation means when it is determined that the vehicle is in a limit running state. The vehicle longitudinal speed estimation device according to claim 1, further comprising a lateral acceleration measuring unit that measures a lateral acceleration of the vehicle, wherein the vehicle model response calculating unit includes a wheel rotational speed and a steering wheel angle of the left and right steered wheels. Is used as the input to estimate the standard lateral acceleration or standard yaw rate from the vehicle model,
The running state determination unit is configured such that a deviation between the lateral acceleration measured by the lateral acceleration measuring unit and the reference lateral acceleration is equal to or greater than a threshold value, or a deviation between the yaw rate measured by the yaw rate measuring unit and the reference yaw rate is A vehicle front-rear speed estimation device that determines that the traveling state of the vehicle is a predetermined limit traveling state when the threshold is equal to or greater than a threshold value.   3. The vehicle longitudinal speed estimation device according to claim 1, comprising: a skid prevention control device that prevents the vehicle from slipping; and a braking control device that controls a braking force of the vehicle, wherein the running state determination is performed. And a vehicle front-rear speed estimation device that determines that the traveling state of the vehicle is a predetermined traveling state when one or both of the skid prevention control device and the braking control device are operating. 4. The vehicle longitudinal speed estimation device according to claim 1, wherein when the travel state determination unit determines that the vehicle is in a predetermined limit travel state, the first immediately before the determination is performed. A vehicle longitudinal speed estimation device that uses the vehicle longitudinal speed estimated by the vehicle speed estimation means as an initial value of an integration calculation of longitudinal acceleration in the second vehicle speed estimation means.

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