JP2007106338A - Vehicle body speed estimating device for vehicle - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To accurately estimate the vehicle body speed of a vehicle without deciding whether or not a wheel is put in a slip state, and without selecting any arithmetic procedure based on the decision result. <P>SOLUTION: Driving/braking torque Ti of each wheel is calculated, and the wheel speed ωi of each wheel is detected, and the estimated wheel speed ωhi of each wheel and estimated longitudinal acceleration Gxwhi of each wheel, that is, the longitudinal acceleration of the vehicle body at the position of each wheel is calculated according to a wheel model (52) on the basis of the driving/braking torque Ti of each wheel, and the integrated value of the mean values of the longitudinal acceleration Gxwhi is calculated as the variation of the estimated vehicle body speed, and the sum of the previous value of the estimated vehicle body speed Vh and the variation of the estimated body speed is calculated as an estimated vehicle body speed Vh, and feedback based on deviation ωi-ωhi between the wheel speed and estimated wheel speed of each wheel is carried out. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a vehicle body speed estimation device, and more particularly to a vehicle body speed estimation device that estimates a vehicle body speed based on braking / driving torque of each wheel.

As one of body speed estimation devices for four-wheel drive vehicles such as automobiles, for example, as described in Patent Document 1 below, the calculation of the body speed is performed depending on whether any of the four wheels is idling. 2. Description of the Related Art A vehicle speed estimation device that changes a method has been conventionally known.
JP 11-189150 A

  In the vehicle body speed estimation device of the conventional four-wheel drive vehicle as described above, the calculation method of the vehicle body speed is changed depending on whether any of the four wheels is idling (slip state). The vehicle speed can be estimated more accurately than when it is not considered whether any of the four wheels is idling. However, the calculation of the car speed depends on whether any of the wheels is idling. Since the procedure is different, there is a problem that arithmetic control becomes complicated. Further, there is a problem that the vehicle body speed cannot be accurately calculated because it is impossible to accurately determine whether or not the wheel is idling unless an accurate vehicle body speed is obtained.

  The present invention has the above-described problems in the vehicle body speed estimation method for a conventional four-wheel drive vehicle configured such that the vehicle body speed calculation method is changed depending on whether any of the wheels is idling. The main object of the present invention is to calculate the estimated longitudinal acceleration of each wheel by a vehicle model based on the braking / driving torque of each wheel, and to calculate the vehicle body speed based on the estimated longitudinal acceleration of each wheel. Or the vehicle's estimated longitudinal acceleration is calculated by the vehicle model based on the braking / driving torque of each wheel, and the vehicle body speed is estimated based on the estimated longitudinal acceleration of the vehicle. It is to accurately estimate the vehicle body speed without requiring the determination of whether or not and the selection of the calculation procedure based on the determination result.

  According to the present invention, the main problems described above are the means for obtaining the braking / driving torque of each wheel, the wheel speed detecting means for detecting the wheel speed of each wheel, and the braking / driving torque of each wheel as inputs. Estimated wheel speed calculation means for calculating the estimated wheel speed of each wheel based on the braking / driving torque of each wheel using a preset vehicle model with the estimated wheel speed as an output, and based on the braking / driving torque of each wheel, A first estimated longitudinal acceleration is calculated, a second estimated longitudinal acceleration of each wheel is calculated based on the estimated wheel speed of each wheel and the wheel speed of each wheel detected by the wheel speed detecting means, Estimated longitudinal acceleration calculation means for computing the estimated longitudinal acceleration of each wheel based on the first estimated longitudinal acceleration of the wheel and the second estimated longitudinal acceleration of each wheel, and estimation based on the estimated longitudinal acceleration of each wheel A vehicle body speed estimation device (structure of claim 1) characterized by having a body speed calculating means, a means for determining braking / driving torque of each wheel, and longitudinal acceleration detection for detecting longitudinal acceleration of the vehicle And an estimated longitudinal acceleration calculating means for calculating the estimated longitudinal acceleration of the vehicle based on the braking / driving torque of each wheel by a preset vehicle model using the braking / driving torque of each wheel as an input and the estimated longitudinal acceleration of the vehicle as an output. Means for calculating an estimated vehicle body speed based on the estimated longitudinal acceleration of the vehicle, the estimated longitudinal acceleration calculating means calculates a first estimated longitudinal acceleration of the vehicle based on braking / driving torque of each wheel, A second estimated longitudinal acceleration of the vehicle is calculated based on the estimated longitudinal acceleration of the vehicle and the longitudinal acceleration of the vehicle detected by the longitudinal acceleration detecting means, and the first estimation of the vehicle is performed. It is achieved by the vehicle speed estimation device of the vehicle, characterized in that for calculating the estimated longitudinal acceleration of the vehicle based on the second estimated longitudinal acceleration of the longitudinal acceleration and the vehicle (the third aspect).

  According to the present invention, in order to effectively achieve the above main problem, in the configuration of claim 1, the means for calculating the estimated vehicle body speed includes the first estimated longitudinal acceleration and the The sum of the second estimated longitudinal acceleration of each wheel is calculated as the estimated longitudinal acceleration of each wheel, the average value of the estimated longitudinal acceleration of each wheel is calculated as the estimated longitudinal acceleration of the vehicle, and the estimated longitudinal acceleration of the vehicle is calculated. The estimated vehicle body speed is calculated on the basis of (the configuration of claim 2).

  According to the present invention, in order to effectively achieve the main problems described above, the vehicle according to any one of claims 1 to 3, wherein the vehicle applies braking / driving torque to each of the four wheels independently of each other. It is comprised so that it may be a four-wheel drive vehicle provided with the drive torque provision means (structure of Claim 4).

  According to the configuration of claim 1, the estimated wheel speed of each wheel is set based on the braking / driving torque of each wheel based on the braking / driving torque of each wheel based on the preset vehicle model using the braking / driving torque of each wheel as an input and the estimated wheel speed of each wheel as an output. Is calculated, the first estimated longitudinal acceleration of each wheel is calculated based on the braking / driving torque of each wheel, and each wheel is detected based on the estimated wheel speed of each wheel and the wheel speed of each wheel detected by the wheel speed detecting means. A second estimated longitudinal acceleration of the wheel is calculated, and an estimated longitudinal acceleration of each wheel is calculated based on the first estimated longitudinal acceleration of each wheel and the second estimated longitudinal acceleration of each wheel, and the estimated longitudinal acceleration of each wheel. Therefore, the vehicle body speed of the vehicle can be calculated without the need to determine whether or not the wheel is idling and to select a calculation procedure based on the determination result, as will be described in detail later. It is possible to estimate the probability.

  According to the configuration of claim 2, the sum of the first estimated longitudinal acceleration of each wheel and the second estimated longitudinal acceleration of each wheel is calculated as the estimated longitudinal acceleration of each wheel, and the estimated longitudinal acceleration of each wheel is calculated. Since the average value is calculated as the estimated longitudinal acceleration of the vehicle, and the estimated vehicle speed is calculated based on the estimated longitudinal acceleration of the vehicle, the estimated longitudinal acceleration of the vehicle is accurately calculated as described in detail later. Speed can be calculated accurately.

  According to the third aspect of the present invention, the estimated longitudinal acceleration of the vehicle is determined based on the braking / driving torque of each wheel by a preset vehicle model using the braking / driving torque of each wheel as an input and the estimated longitudinal acceleration of the vehicle as an output. The calculated vehicle body speed is calculated based on the estimated longitudinal acceleration of the vehicle, but the first estimated longitudinal acceleration of the vehicle is calculated based on the braking / driving torque of each wheel to detect the estimated longitudinal acceleration and longitudinal acceleration of the vehicle. The second estimated longitudinal acceleration of the vehicle is calculated based on the longitudinal acceleration of the vehicle detected by the means, and the estimated longitudinal acceleration of the vehicle is calculated based on the first estimated longitudinal acceleration of the vehicle and the second estimated longitudinal acceleration of the vehicle. As described later in detail, the vehicle body speed of the vehicle is corrected without requiring determination of whether or not the wheel is in an idle state and selection of a calculation procedure based on the determination result. It can be estimated to.

  According to the fourth aspect of the present invention, the vehicle is a four-wheel drive vehicle including braking / driving torque applying means for applying braking / driving torque to each of the four wheels independently of each other. The speed can be estimated accurately.

[Preferred embodiment of problem solving means]
In general, the inertial mass of the wheel is J, the wheel speed of the wheel is ω, the braking / driving torque of the wheel is T, the friction coefficient of the road surface is μ, the ground contact load of the wheel is W, and the rotation radius of the wheel is R. , Ω dot is a differential value of the wheel speed ω, the equation of motion of the wheel rotation system is expressed by the following equation 1.

Assuming that the differential value of the μ dot, that is, the friction coefficient μ of the road surface is 0, and formulating the state equation with the wheel speed ω of the wheel and the friction coefficient μ of the road surface as state variables, the following equation 2 is obtained.

The friction coefficient μ of the road surface is replaced with the longitudinal acceleration Gx of the wheel, the matrix of the estimated wheel speed ωh of the wheel and the estimated longitudinal acceleration Gxwh of the wheel is Xh as shown in the following equation 3, and the system matrix and the control vector are respectively expressed by the following equations 4 And 5 as A and B, Equation 2 above becomes Equation 6 below.

Here, when a feedback system based on the deviation between the wheel speed ω of the wheel and the estimated wheel speed ωh of the wheel is configured, G is a feedback gain, C = [10], and the above equation 6 is expressed by the following equation 7. Become.

When the deviation between Xh and X is ε as shown in the following equation 8, the differential value ε dot of the deviation ε is expressed by the following equation 9.

In order for the magnitude of the deviation ε to decrease and eventually become 0 with the passage of time, the eigenvalue of the coefficient (A-GC) of the deviation ε only needs to be negative. What is necessary is just to determine the feedback gain G so that it may become negative. Therefore, the Laplace operator is set as s as shown in the following formulas 10 and 11, and the following formula 10 is solved for the feedback gain vector G with I as the unit matrix.

From the above equations 10 and 11, the following equation 12 is established, and thus the following equation 13 is established.

From the above equation 13, the following equations 14 and 15 hold, and λ ₁ and λ ₂ (both negative values) may be set as compatible constants, for example, by experiments.

Therefore, according to one preferred aspect of the present invention, in the configuration of claim 1 or 2, the identification symbols of the left front wheel, the right front wheel, the left rear wheel, and the right rear wheel are i (i = fl, fr, rl). Rr), Xh, A, and B are the following equations 16 to 18 corresponding to the above equations 3 to 5, respectively, the feedback gain G is as the following equation 19, and the suffixes of the previous and current values are n And n−1, Xh dot (n) is calculated in accordance with the following equation 20 corresponding to the above equation 7, and Xh dot (n) is integrated, so that the estimated wheel speed ωhi of each wheel and the estimation of each wheel are calculated. The longitudinal acceleration Gxwhi is configured to be calculated (preferred aspect 1).

  According to another preferred aspect of the present invention, in the configuration of claim 2, the means for calculating the estimated vehicle speed calculates the average value of the estimated longitudinal acceleration of each wheel at a predetermined time interval before and after the estimation of the vehicle. Calculated as acceleration, integrated value of estimated longitudinal acceleration of vehicle is calculated as change in estimated vehicle speed, and estimated vehicle speed is calculated as the sum of previously calculated estimated vehicle speed and estimated vehicle speed change (Preferred embodiment 2).

According to another preferred aspect of the present invention, in the configuration of the preferred aspect 2, the means for calculating the estimated vehicle body speed is an estimated longitudinal acceleration Gxwhi (i = fl, fr, rl, rr) is calculated, and the estimated vehicle speed Vh _n is calculated according to the following equation 21 with the previously calculated estimated vehicle speed Vh _n-1 (preferred aspect 3).
Vh _n = Vh _n-1 + ∫ (Gxwhfl + Gxwhfr + Gxwhrl + Gxwhrr) dt / 4 (21)

In general, the inertial masses of the front and rear wheels are If and Ir, the braking / driving torques of the front and rear wheels are Tf and Tr, the rotational radii of the front and rear wheels are Rf and Rr, respectively, and the mass of the vehicle body is Assuming M and the vehicle body speed as V, the equation of motion in the front-rear direction of the vehicle when the rotation system of the front wheels and the rear wheels is taken into consideration is expressed by the following expression 22, and the following expression 23 is established.

From equation 23, the control vector B is as shown in equation 24 below, and when a feedback system based on the deviation between the vehicle longitudinal acceleration Gxh and the vehicle estimated longitudinal acceleration Gxh is constructed, Equation 25 is obtained.

From the above equation 25, it is understood that the estimated vehicle body speed Vh can be calculated according to the following equation 26.

  In order to increase the responsiveness of the estimated longitudinal acceleration Gxh of the vehicle, the feedback gain G (> 0) may be increased. In this case, higher order error components such as sensor noise also increase. There is a high risk that errors will accumulate in the estimated vehicle speed Vh. Therefore, it is preferable to perform an experiment in advance and set the feedback gain G so that the estimated vehicle body speed Vh becomes an appropriate value with respect to the detected value of the ground vehicle body speed meter.

Therefore, according to another preferred aspect of the present invention, in the configuration of claim 3, B is a control vector represented by the above equation 24, G is a feedback gain set as described above, and The unit for calculating the estimated vehicle speed is set to calculate the estimated vehicle speed Vh _n according to the following equation 27 corresponding to the above-described equation 26 (preferred aspect 4). ).

  The present invention will now be described in detail with reference to a few preferred embodiments with reference to the accompanying drawings.

  FIG. 1 is a schematic configuration diagram showing a first embodiment of a vehicle body speed estimating device according to the present invention applied to an in-wheel motor type four-wheel drive vehicle.

  In FIG. 1, 10FL and 10FR respectively indicate left and right front wheels that are steering wheels, and 10RL and 10RR respectively indicate left and right rear wheels that are non-steering wheels. Electric motors 12FL and 12FR, which are in-wheel motors, are incorporated in the left and right front wheels 10FL and 10FR, respectively, and the left and right front wheels 10FL and 10FR are directly driven by the electric motors 12FL and 12FR. The motors 12FL and 12FR also function as regenerative generators for the left and right front wheels during braking, respectively, and may apply regenerative braking force directly to the left and right front wheels 10FL and 10FR.

  Similarly, electric motors 12RL and 12RR which are in-wheel motors are incorporated in the left and right rear wheels 10RL and 10RR, respectively, and the left and right front wheels 10RL and 10RR are directly driven by the electric motors 12RL and 12RR. The motors 12RL and 12RR also function as left and right rear wheel generators during braking, respectively, and may apply regenerative braking force directly to the left and right rear wheels 10RL and 10RR.

  The driving force of the electric motors 12FL to 12RR is controlled by the driving force control electronic control device 16 based on the accelerator opening φ as the accelerator pedal depression amount not shown in FIG. . The regenerative braking force of the electric motors 12FL to 12RR may also be controlled by the driving force control electronic control device 16.

  Although not shown in detail in FIG. 1, the driving force control electronic control device 16 includes a microcomputer and a drive circuit. The microcomputer includes, for example, a CPU, a ROM, a RAM, and an input / output port device. And may have a general configuration in which they are connected to each other by a bidirectional common bus.

  The friction braking force of the left and right front wheels 10FL, 10FR and the left and right rear wheels 10RL, 10RR is controlled by controlling the braking pressure of the corresponding wheel cylinders 22FL, 22FR, 22RL, 22RR by the hydraulic circuit 20 of the friction braking device 18. The Although not shown in the drawing, the hydraulic circuit 20 includes a reservoir, an oil pump, various valve devices, etc., and the braking pressure of each wheel cylinder is normally determined by the amount of depression of the brake pedal 24 and depression of the brake pedal 24 by the driver. The brake pedal is controlled by the driver by controlling the oil pump and various valve devices by the electronic control device 28 for controlling the braking force as necessary. Control is performed regardless of the amount of depression of 24.

  Although not shown in detail in FIG. 1, the electronic control device 28 for controlling the braking force also includes a microcomputer and a drive circuit. The microcomputer includes, for example, a CPU, a ROM, a RAM, and an input / output port device. And may have a general configuration in which they are connected to each other by a bidirectional common bus.

  In addition to the signal indicating the accelerator opening φ from the accelerator opening sensor 14, the driving force control electronic control device 16 receives the wheel speed ωi (i = fl, fr, rl, rr) of each wheel from the wheel speed sensor 30 i. , Various state quantities of the vehicle such as the yaw rate γ of the vehicle are input from another sensor 34 such as a yaw rate sensor. Also, the braking force control electronic control unit 28 has a signal indicating the master cylinder pressure Pm from the pressure sensor 36, and a corresponding wheel braking pressure (wheel cylinder pressure) Pbi (i = fl, fr, rl,) from the pressure sensors 38FL to 38RR. rr) is input. The driving force control electronic control device 16 and the braking force control electronic control device 28 exchange signals with each other as necessary.

  The electronic control unit 16 for controlling the driving force controls the target braking / driving torque of the vehicle by setting the driving torque to a positive value and the braking torque to a negative value based on the accelerator opening φ and the master cylinder pressure Pm that are the acceleration / deceleration operation amount of the driver. Tvt is calculated, and the target braking / driving torque Tti (i = fl, fr, rl, rr) of each wheel is calculated according to a predetermined distribution ratio based on the target braking / driving torque Tvt, and the braking / driving torque Ti ( i = fl, fr, rl, rr) controls the motors 12FL to 12RR so that the respective target braking / driving torques Tti correspond to each other, or outputs a command signal to the braking force control electronic control device 28 to control the braking force. The electronic control device 28 controls the hydraulic circuit 20.

  FIG. 2 shows a signal flow in the first embodiment. In FIG. 2, 50 shows an actual vehicle, and 52 shows a vehicle model for estimating the longitudinal acceleration of each wheel. As shown in FIG. 2, the wheel speed ωi of each wheel is changed by applying braking / driving torque Ti to each wheel of the vehicle 50.

  The multiplier 54 of the vehicle model 52 receives the braking / driving torque Ti of each wheel as a value equal to the target braking / driving torque Tti, and the multiplier 54 controls the control vector B expressed by the above equation 18 and the braking / driving of each wheel. The product of the torque Ti is output to the adder 56. The wheel speed ωi of each wheel is input to the positive input terminal of the adder 58, and the estimated wheel speed ωhi of each wheel output from the multiplier 60 is input to the negative input terminal of the adder 58. The output of the adder 58, that is, the wheel speed deviation ωi−ωhi is input to the multiplier 62, and the adder 58 adds the product of the wheel speed deviation ωi−ωhi and the feedback gain G expressed by the above equation 19. To the device 56. Note that, by appropriately setting λ1 and λ2 (both negative values) in the above formulas 14 and 15, the feedback gain G has an eigenvalue of the coefficient of deviation ε (A−GC) in the above formula 9. It is set to be negative.

  The output of the adder 56 is a differential value of Xh expressed by the above equation 16, that is, an Xh dot, and is input to the integrator 64. The output of the integrator 64, that is, Xh expressed by the above equation 16 is input to the multipliers 60 and 66. A multiplier 60 multiplies Xh by a matrix [1 0] to output an estimated wheel speed ωhi of each wheel, and a multiplier 66 multiplies Xh by a matrix [0 1] to thereby estimate an estimated longitudinal acceleration Gxwhi of each wheel. (I = fl, fr, rl, rr) is output.

  The output of the integrator 64, that is, Xh expressed by the above equation 16 is input to the multiplier 68. The multiplier 68 supplies the product of the system matrix A and Xh expressed by the above equation 17 to the adder 56. Output. Therefore, the adder 56 "the product of the control vector B and the braking / driving torque Ti of each wheel", "the product of the wheel speed deviation ωi-ωhi and the feedback gain G", and "the product of the system matrix A and Xh". Is calculated as a differential value of Xh.

Accordingly, in the first embodiment, although not shown in the flowchart, Xh dot (n) is calculated according to the above equation 20 based on the braking / driving torque Ti of each wheel, and Xh dot (n) is integrated. the Rukoto estimated wheel speed ωhi and the estimated longitudinal acceleration Gxwhi of each wheel of each wheel is calculated, the estimated vehicle speed Vh _n according to the above equation 21 is calculated the previous value of the estimated vehicle speed Vh as Vh _n-1. Note that the previous value Vh _n−1 of the estimated vehicle speed is set to 0 at the start of the calculation control of the estimated vehicle speed.

  Thus, according to the first embodiment, the estimated longitudinal acceleration Gxwhi of each wheel, that is, the estimated longitudinal acceleration of the vehicle body at each wheel position, is calculated based on the braking / driving torque Ti of each wheel, and the integrated value of these sums is calculated. Since the estimated vehicle speed Vh is calculated as the amount of change in the estimated vehicle speed, it is possible to accurately determine the vehicle body speed of the vehicle without having to determine whether or not the wheel is idling and to select a calculation procedure based on the determination result. Can be estimated.

  In particular, there are uncertainties such as modeling errors and uncertainties in the friction coefficient of the road surface between the wheel speeds of each wheel calculated by the vehicle model and the wheel speeds of each wheel of the actual vehicle. According to the first embodiment, the uncertainty of the friction coefficient of the road surface of each wheel is estimated by the observer, the estimated friction coefficient of the road surface of each wheel is replaced with the estimated longitudinal acceleration of each wheel, and the average value thereof is Since the estimated longitudinal acceleration of the vehicle body is used, the vehicle body speed of the vehicle can be accurately estimated from this point.

  Further, according to the illustrated embodiment 1, since feedback is performed based on the deviation ωi−ωhi between the wheel speed of each wheel and the estimated wheel speed, the estimation error of the vehicle body speed due to the modeling error can be reliably reduced. Can do.

  When the vehicle body speed is estimated based on the longitudinal acceleration of the vehicle detected by the longitudinal acceleration sensor, the longitudinal acceleration of the vehicle is corrected according to the slope of the vehicle when traveling on a slope, or the zero point drift of the longitudinal acceleration sensor is detected. However, according to Example 1 shown in the drawing, the vehicle longitudinal acceleration correction and the longitudinal acceleration of the vehicle according to the slope of the hill during running on the slope are problematic. It is not necessary to correct the sensor zero drift, and there is no problem of accumulation of detection errors.

  FIG. 3 is a schematic diagram showing a second embodiment of a vehicle body speed estimation device according to the present invention applied to an in-wheel motor type four-wheel drive vehicle, and FIG. 4 is a diagram showing a signal flow in the second embodiment. is there. In FIGS. 3 and 4, the same members as those shown in FIGS. 1 and 2 are denoted by the same reference numerals as those in FIGS.

  In the second embodiment, the driving force control electronic control device 16 has a signal indicating the longitudinal acceleration Gx of the vehicle from the longitudinal acceleration sensor 32 in addition to the signal indicating the accelerator opening φ from the accelerator opening sensor 14. Various state quantities of the vehicle such as the yaw rate γ of the vehicle are input from another sensor 34 such as a yaw rate sensor. The electronic control unit 16 for driving force control calculates the braking / driving torque Tf of the front wheels as the sum of the braking / driving torques Tfl and Tfr of the left and right front wheels based on the braking / driving torque Ti of each wheel, and also controls the braking / driving of the left and right rear wheels. The braking / driving torque Tr of the rear wheels is calculated as the sum of the torques Trl and Trr.

  In FIG. 4 showing a signal flow in the second embodiment, 50 indicates an actual vehicle, and 72 indicates a vehicle model for estimating the longitudinal acceleration of the vehicle. As shown in FIG. 4, the longitudinal acceleration Gx of the vehicle is changed by applying braking / driving torques Tf and Tr to the front and rear wheels of the vehicle 50, respectively.

  The multiplier 74 of the vehicle model 72 receives the braking / driving torque Tf of the front wheels and the braking / driving torque Tr of the rear wheels, and the multiplier 74 uses the control vector B expressed by the above equation 24 and the braking / driving torque Tf of the front wheels. The product of the rear wheel braking / driving torque Tr is output to the adder 76. The longitudinal acceleration Gx of the vehicle is input to the plus input terminal of the adder 78, and the estimated longitudinal acceleration Gxh of the vehicle output from the adder 76 is inputted to the minus input terminal of the adder 78. The output of the adder 78, that is, the deviation Gx−Gxh of the longitudinal acceleration of the vehicle is input to the integrator 80, and the integrator 80 outputs the integrated value of the deviation Gx−Gxh to the multiplier 82.

  The multiplier 82 outputs the product of the integrated value of the deviation Gx−Gxh of the longitudinal acceleration of the vehicle and the feedback gain G to the adder 76. The output of the adder 76 is the estimated longitudinal acceleration Gxh of the vehicle and is input to the integrator 74. The integrator 74 outputs an estimated vehicle body speed Vh of the vehicle by integrating the estimated longitudinal acceleration Gxh of the vehicle. The feedback gain G is set so that the estimated vehicle speed Vh is an appropriate value with respect to the detected value of the ground vehicle speedometer by experiment.

Therefore, in the second embodiment, although not shown in the flowchart, the front wheel braking / driving torque Tf, the rear wheel braking / driving torque Tr, the previous value Gx _n-1 of the longitudinal acceleration Gx of the vehicle, and the estimation of the vehicle Based on the previous value Gxh _n−1 of the longitudinal acceleration Gxh, the estimated vehicle speed Vh _n is calculated according to the above equation 27. At the start of the calculation control of the estimated vehicle body speed, the previous value Gxn _-1 of the vehicle longitudinal acceleration Gx and the previous value Gxhn _-1 of the estimated vehicle longitudinal acceleration Gxh are set to 0, respectively.

  Thus, according to the second embodiment, the estimated longitudinal acceleration Gxh of the vehicle is calculated based on the braking / driving torque Tf of the front wheels and the braking / driving torque Tr of the rear wheels, and the estimated vehicle speed Vh is calculated as an integral value thereof. As in the case of the first embodiment, the vehicle body speed of the vehicle can be accurately estimated without determining whether or not the wheel is idling and selecting the calculation procedure based on the determination result.

  Further, according to the illustrated embodiment 2, feedback based on the deviation Gx−Gxh between the longitudinal acceleration Gx of the vehicle and the estimated longitudinal acceleration Gxh is performed, so that the estimation error of the vehicle speed due to the modeling error is reliably reduced. be able to.

  In the second embodiment, correction of the longitudinal acceleration of the vehicle and correction of the zero point drift of the longitudinal acceleration sensor may be performed according to the slope of the slope when traveling on a slope, and in this case, based on the deviation Gx-Gxh. The feedback can be performed more accurately, whereby the vehicle body speed can be estimated more accurately.

  Although the present invention has been described in detail with reference to specific embodiments, the present invention is not limited to the above-described embodiments, and various other embodiments are possible within the scope of the present invention. It will be apparent to those skilled in the art.

  For example, in the first embodiment, the vehicle body speed is estimated regardless of whether the braking / driving torque Ti of each wheel is a driving torque or a braking torque. In the second embodiment, the front wheel The vehicle body speed is estimated regardless of whether the braking / driving torque Tf and the braking / driving torque Tr of the rear wheels are the driving torque or the braking torque, but the target braking / driving torque Tvt of the vehicle is the driving torque. It may be modified so that the vehicle body speed is estimated only in some cases or only in the case of braking torque.

  In the first and second embodiments described above, the vehicle is an in-wheel motor type four-wheel drive vehicle, but the vehicle to which the present invention is applied is a four-wheel drive vehicle other than the in-wheel motor type four-wheel drive vehicle. In this case, the drive device may be a drive device other than an electric motor, and the vehicle to which the present invention is applied may be a front wheel drive vehicle or a rear wheel drive vehicle.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a schematic configuration diagram showing a first embodiment of a vehicle body speed estimation device according to the present invention applied to a wheel-in-motor four-wheel drive vehicle. FIG. 3 is a diagram showing a signal flow in Example 1. It is a schematic block diagram which shows Example 2 of the vehicle body speed estimation apparatus of the vehicle by this invention applied to the wheel-in-motor type four-wheel drive vehicle. FIG. 6 is a diagram showing a signal flow in Example 2.

Explanation of symbols

12FL to 12RR Electric motor 14 Accelerator opening sensor 16 Electronic control device for driving force control 18 Friction braking device 24 Brake pedal 28 Electronic control device for braking force control 30 Wheel speed sensor 32 Longitudinal acceleration sensor 34 Other sensors 36, 38FL to 38RR Pressure Sensor

Claims (4)

  By means of a vehicle model set in advance as a means for determining the braking / driving torque of each wheel, a wheel speed detecting means for detecting the wheel speed of each wheel, and an estimated wheel speed of each wheel as an output by inputting the braking / driving torque of each wheel. Estimated wheel speed calculating means for calculating an estimated wheel speed of each wheel based on the braking / driving torque of each wheel; calculating a first estimated longitudinal acceleration of each wheel based on the braking / driving torque of each wheel; The second estimated longitudinal acceleration of each wheel is calculated based on the estimated wheel speed of each wheel and the wheel speed of each wheel detected by the wheel speed detecting means, and the first estimated longitudinal acceleration of each wheel and each wheel are calculated. An estimated longitudinal acceleration calculating means for calculating an estimated longitudinal acceleration of each wheel based on the second estimated longitudinal acceleration; and a means for calculating an estimated vehicle body speed based on the estimated longitudinal acceleration of each wheel. Vehicle speed estimating apparatus of a vehicle according to claim.   The means for calculating the estimated vehicle body speed calculates the sum of the first estimated longitudinal acceleration of each wheel and the second estimated longitudinal acceleration of each wheel as the estimated longitudinal acceleration of each wheel, and 2. The vehicle body speed estimation device according to claim 1, wherein an average acceleration value is calculated as an estimated longitudinal acceleration of the vehicle, and an estimated vehicle body speed is calculated based on the estimated longitudinal acceleration of the vehicle.   Each wheel according to a vehicle model set in advance by means for obtaining braking / driving torque of each wheel, longitudinal acceleration detecting means for detecting longitudinal acceleration of the vehicle, and input of braking / driving torque of each wheel and output of estimated longitudinal acceleration of the vehicle. An estimated longitudinal acceleration calculating means for calculating an estimated longitudinal acceleration of the vehicle based on the braking / driving torque of the vehicle, and a means for calculating an estimated vehicle body speed based on the estimated longitudinal acceleration of the vehicle, wherein the estimated longitudinal acceleration calculating means comprises: A first estimated longitudinal acceleration of the vehicle is calculated based on the braking / driving torque of each wheel, and a second estimated vehicle is calculated based on the estimated longitudinal acceleration of the vehicle and the longitudinal acceleration of the vehicle detected by the longitudinal acceleration detecting means. Calculating a longitudinal acceleration, and calculating an estimated longitudinal acceleration of the vehicle based on a first estimated longitudinal acceleration of the vehicle and a second estimated longitudinal acceleration of the vehicle. Vehicle speed estimating apparatus of a vehicle according to claim.   4. The vehicle body speed estimation device according to claim 1, wherein the vehicle is a four-wheel drive vehicle provided with braking / driving torque applying means for applying braking / driving torque to each of the four wheels independently of each other. .

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