JP2008049996A - Motion controller of vehicle - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a motion controller of a vehicle for reducing a drift for a vehicle having a mechanism generating a yaw moment and for improving robustness. <P>SOLUTION: The motion controller for controlling motion of the vehicle includes a yaw moment generation mechanism 9 for making the vehicle generate the yaw moment; status sensors 1, 2, 3, 4, 5 for measuring a status quantity of the vehicle by the mechanism 9; and a control means 7 for applying feedback control. The control means 7 performs the feedback control by taking a ratio of dissipation power, which is a thermal loss per unit time caused by the slip of tires in travelling for the status quantity of the vehicle measured by the sensors 1, 2, 3, 4, 5, into account. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a vehicle motion control method, and more particularly to a vehicle motion control apparatus having a mechanism for generating a yaw moment in a vehicle.

In general, when controlling the movement of a vehicle, yaw rate feedback is used to improve maneuverability (make the vehicle move responsively and responsively to the driver's steering wheel operation). Side slip angle feedback is often used to do this. As a reference, Table 1 summarizes the control laws for representative papers (Non-Patent Documents 1 to 4) related to vehicle motion control that have been published over the past 10 years. Either or both of yaw rate feedback and side-slip angle feedback are used.

  In the vehicle motion control described above, the side slip angle uses an estimated value calculated from the yaw rate and lateral acceleration, and since the integration calculation is the main component, drift tends to occur, and a filter is used to reduce this drift. And phase error occurs. For this reason, even when presently performing side slip angle feedback, it is assumed that noise such as drift is included, and the magnitude of the feedback gain is limited.

  A technique disclosed in Japanese Patent Application Laid-Open No. H10-228561 is to solve the problem in the case where such a side slip angle is used for control. According to this, the robustness with respect to the drift term at the time of side slip angle estimation can be improved, and the phase can be improved as compared with the case of simply performing side slip angle feedback.

The outline of the method of Patent Document 1 will be described below. In the control theory so far, the characteristics of the controlled object are described by the equation of motion, but in Patent Document 1, the balance equation of the total input / output power of the controlled object is used. Specifically, as shown in the following equation, a motion equation for each degree of freedom of the system is displayed as a vector, and this is multiplied by a velocity vector. The input power includes not only the control input but also the disturbance input, and since the controlled object is not limited to the passive element, if there is an energy source inside and this affects the motion, it is treated as a disturbance input.
Here, d, e, q, u, v, zεR ⁿ and MεR ^{n × n} are positive definite inertia matrices, and n is the degree of freedom of the controlled object. q is a generalized coordinate, u is a control input, v is a force input disturbance, and z is a displacement input disturbance. d is Coriolis force, centrifugal force, damping force, etc., e is potential force.

Consider the following evaluation function for the above system.
Is the power applied by the control device to the controlled object. r is a weighting factor.

Next, a control u (t) that minimizes Equation 2 is obtained. The following scalar function L is defined to determine the necessary conditions for optimal control.
Here, κ is an undetermined constant. The value in {} on the right side is the same as the left side of Equation 1 and is the total power balance of the controlled object, so it satisfies the energy conservation law and is always zero.

Therefore, the condition for minimizing the integral of L expressed by Equation 3 also minimizes Equation 2. Therefore, the following equation that applies the variational principle with q as a variable to the function L gives a necessary condition for u to be optimal control. Since L is a linear expression with respect to u, ∂L / ∂u has no meaning and the following expression includes all information related to control.

From equation 4, the control law is obtained as follows.
The first line of the above equation is the control for the external force v and the q dependence of the inertia, the second line is the control for the Coriolis force, the centrifugal force and the damping force, the third line is the control of the potential force and its q dependency and the external force z, The fourth line is control for reducing the evaluation function, and the meaning of each is clear. The above is the outline of Patent Document 1.

Japanese Patent Application No. 2006-92243 Inoue et al., Improvement of vehicle motion performance by braking force distribution control, Preprints 921 1992-5 Yamamoto et al., Active braking force control to improve vehicle stability near the limit Furukawa et al., Vehicle motion control by tire lateral force monitoring, Automobile Engineering Society Proceedings 9930397 Kotake et al., Theoretical analysis on cooperative control of active steering and DYC, Proceedings of the Society of Automotive Engineers of Japan Masato Abe, Motor Movement and Control, Sankaido, P10

  However, the control device of Patent Document 1 does not disclose any control for a vehicle having a mechanism that generates a yaw moment. Therefore, it has been desired to develop a device to which the control law of Patent Document 1 is applied for specific vehicle motion control.

  In view of such a situation, the present invention is intended to provide a motion control device that can reduce drift and improve robustness with respect to a vehicle having a mechanism that generates a yaw moment.

In order to achieve the above-described object of the present invention, a vehicle motion control apparatus according to the present invention includes:
A yaw moment generating mechanism for generating a yaw moment in the vehicle;
A state sensor for measuring a vehicle state quantity by the yaw moment generation mechanism;
Control means for performing feedback control in consideration of a ratio of dissipated power, which is a heat loss per unit time generated by slipping of a running tire with respect to a vehicle state quantity measured by the state sensor;
It comprises.

Here, the control means includes a term of the following formula in its control law:
It is.

  Further, the state quantity of the vehicle may be a yaw rate.

  Further, the state quantity of the vehicle may be a side slip speed or a side slip angle.

Also, the dissipated power may be approximated by:
_T1 , _dT2 , and _dT3 are given by the following equations:
However, S ₁ is the left front wheel, S ₂ is the right front wheel, S ₃ is the left rear wheel, S ₄ is a function approximating the lateral force generated by each tire of the right rear wheel, δ is the front wheel steering angle, l _f is the distance between the vehicle center of gravity and the front wheels, l _r is the distance between the vehicle center of gravity and the rear wheels, and l _t is the tread.

  Further, the yaw moment generating mechanism may be composed of driving means that can independently control the driving force of each wheel of the vehicle.

Here, the control means may have its control law given by the following equation:
Where κ is a constant, r _i is a weighting factor, V _x is the longitudinal speed of the vehicle, and V _y is the side slip speed of the vehicle.
Where F _ix and F _iy are centrifugal forces acting on the vehicle, S ₁ is the left front wheel, S ₂ is the right front wheel, S ₃ is the left rear wheel, and S ₄ is the lateral force generated by each tire of the right rear wheel. , Δ is the front wheel steering angle, l _f is the distance between the vehicle center of gravity and the front wheels, l _r is the distance between the vehicle center of gravity and the rear wheels, and l _t is the tread.

Further, a function approximating the lateral force generated by each tire may be given by the following tire characteristic equation derived from Fiala's theory,
However,
However, K is the cornering power of the tire, W _i is a load of each wheel, mu is the friction coefficient of the road surface and the tires, beta _i is the sideslip angle.

Furthermore, the function that approximates the lateral force generated by each tire may be given by the following tire characteristic equation derived from the Magic Formula theory,
Where W _i is the load of each wheel, μ is the friction coefficient between the road surface and the tire, β _i is the side slip angle, and C and B are constants.

  Further, the yaw moment generating mechanism may be composed of active suspension means that can control each wheel of the vehicle independently.

Here, the control means may have its control law given by the following equation:
That is,
Where l _f is the distance between the center of gravity of the vehicle and the front wheel, l _r is the distance between the center of gravity of the vehicle and the rear wheel, μ is the friction coefficient between the road surface and the tire, W _i is the load of each wheel, a is a constant, Γ _i , Θ _i is given by:
However, Y _i is a function that approximates the lateral force generated by each tire of Y ₁ being the left front wheel, Y ₂ being the right front wheel, Y ₃ being the left rear wheel, and Y ₄ being the right rear wheel.

In addition, the function that approximates the lateral force generated by each tire may be given by the following tire characteristic equation derived from Magic Formula theory,
Here, β _i is a side slip angle, and C and B are constants.

  Further, the yaw moment generating mechanism may be composed of a steering control means capable of controlling the steering angle of the vehicle.

  The vehicle motion control apparatus of the present invention has the advantages that drift can be reduced and robustness can be improved with respect to a vehicle having a mechanism for generating a yaw moment.

  The best mode for carrying out the present invention will be described below with reference to the drawings. In the vehicle motion control apparatus of the present invention, referring to the concept of the optimum control method of the system presented in Patent Document 1, a new evaluation function related to vehicle motion control is newly set and a unique device is added to the conventional side slip. It introduces a new control law that replaces angular feedback. In the following, an example applied to an electric vehicle and an active suspension control device capable of independently controlling the driving force of each wheel will be described. Application to angle control and the like is also possible. Further, the yaw moment generating mechanism may be a steering control means capable of controlling the steering angle of the vehicle. That is, the present invention may be applied to an optimal control law that controls the relationship between the steering angle and the tire angle.

  First, as a mechanism for generating a yaw moment, FIG. 1 shows a vehicle model for obtaining a control law of a driving device that can independently control the driving force of each wheel of the vehicle, such as an electric vehicle. It is a vehicle model with three degrees of freedom of the vehicle body that ignores the roll and pitch for the sake of simplicity. The vehicle model in the illustrated example does not consider rolling motion and pitch motion, but considers load movement that acts on each wheel due to acceleration acting on the center of gravity of the vehicle.

When the braking / driving force X _i and the lateral force Y _i generated in the tire are defined as shown in FIG. 1, the equation of motion of the vehicle model is as follows.
Here, m is the vehicle mass, I _z is the yaw moment of inertia of the vehicle, l _f is the distance between the vehicle center of gravity and the front wheels, l _r is the distance between the vehicle center of gravity and the rear wheels, l _t is the tread, and V _x is the vehicle longitudinal speed. , V _y is the car

Lateral force S _i acting on tires, using the tire characteristic equation derived from Fiala theory (for example, see Non-Patent Document 5). If the cornering power is K, the vertical load of the tire is W _i , and the side slip angle of the tire is β _i , the lateral force S _i is expressed by the following equation using Fiala's theory.
Here, S ₁ is the left front wheel, S ₂ is the right front wheel, S ₃ is the left rear wheel, S ₄ is a function approximating the lateral force generated by each tire of the right rear wheel, and τ _i is It is given by the formula.
Here, K is the cornering power, W _i of the tire is the friction coefficient of the load of each wheel, mu is a road tires.

Further, the side slip angle β _i is given by the following equation.

Next, each element when the control law of patent document 1 is applied to vehicle motion control is defined. In the vehicle motion, the potential force e does not exist, and the force input disturbance v and the displacement input disturbance z are zero. The state quantity q is defined by the following equation.
The power balance equation is as follows.
The mass matrix M is expressed by the following equation.
In the present invention, since the yaw moment control of the vehicle using the left / right difference of the braking / driving force is assumed, the control input is the yaw moment _Mz input to the vehicle. That is, the control input u is the following equation.

Next, the centrifugal force acting on the vehicle and d, which is the reaction force to the tire generated from the road surface, are expressed by the following equation.
Here, F _ix and F _iy are centrifugal forces acting on the vehicle, and are expressed by the following equations.

Regarding d _i, when considering only the dissipation power is the heat loss per unit time caused by the slip of the tire during running, that is substantially heat loss multiplied by the velocity slip force generated in the tire Therefore, the centrifugal forces F _ix and F _iy acting on the vehicle can be omitted.

Substituting the elements defined above into the power balance equation of Equation 1 yields the following equation.

Here, an object of the present invention is to derive a control law that simultaneously realizes followability and stability with respect to a target yaw rate. Therefore, the following equation is used for the function g of Formula 2 that gives an evaluation of the control performance.
Is a number. The first term of the above formula is the follow-up evaluation for the target yaw rate, and the second term is the stability evaluation.
The number is:
Here, r ₃ is a weighting factor.

Next, the functional L is defined as follows.

Since the term of inertial force included in P disappears, the inertial force in P may be deleted from the beginning. Incidentally it may be zero because d ₁ is small in the normal running.
Here, the partial differential term of the first term on the right side of the above equation is expressed as follows using Equation 16.
Furthermore, when Equations 9 and 10 are used, the above equation is as follows.
As described above, the optimal control law of Equation 23 can be calculated from the vehicle state quantity measured by the sensor or the like.

Here, in motion control of a vehicle having a mechanism for generating a yaw moment, it is important that at least the first term is included in the right side of Equation 23. That is, in the vehicle motion control device of the present invention, it is important to perform control using a control law that takes into account the ratio of the dissipated power to the actual vehicle state quantity. More specifically, it is preferable that the following law is included in the control law.
Amount.

When only the dissipated power is considered and the centrifugal forces F _ix and F _iy acting on the vehicle are omitted, the approximate expression of the dissipated power is given by the following equation from the first term and the right side of Equation 23: It is done.
Here, d _T1 , d _T2 , and d _T3 are given by the following equations.

Since the input yaw moment _Mz has been obtained as described above, the braking / driving torque to be inputted to each wheel is obtained by the following procedure using this value. The braking / driving torque U _i determined by the accelerator amount of the driver and the braking / driving torque T _i determined by allocating the input yaw moment M _z obtained by the optimal control will be considered separately. It is assumed that the braking / driving torque U _i determined by the accelerator amount of the driver is evenly distributed to the four wheels as the braking / driving torque proportional to the accelerator amount. The U _i and T _i are added together to obtain the final braking / driving torque.

Next, consider how to allocate _{T i.} If δ is relatively small, there is a relationship of the following equation between M _z and T _i obtained by optimal control.
Here, r is the radius of the tire. Further, since the braking and driving torque T _i is set so as not to accelerate or decelerate, the following equation holds.
Therefore, the following equation is obtained from the equations 33 and 34.
Thus, the sum of the torques of the left and right wheels was obtained. Furthermore, consider the distribution of front and rear wheels. Here, the distribution ratio of the front and rear wheels is considered using the concept of the tire friction margin. The friction margin of the tire is obtained using the following equation. Here, the tire friction margin means the maximum value of braking / driving power that can be generated when a wheel load and a lateral force are applied, and is expressed by the following equation.
In order to effectively use the grip force of the tire, the left and right wheels are proportionally distributed to the front and rear wheels in proportion to the tire friction margin. That is, T _i is obtained by the following equation.

The effect of the control device of the present invention thus obtained is confirmed by simulation. The vehicle model used was a non-linear model with a total of 7 degrees of freedom, with 3 degrees of freedom for the vehicle body and 4 degrees of freedom for the wheels ignoring the pitch and roll, and the brush model was a brush model. The specifications of the vehicle used for the simulation are values of a general small passenger car. Typical parameters are vehicle mass m = 1490 kg, yaw moment of inertia I _z = 2200 kgm ² , distance between front wheel and vehicle center of gravity l _f = 1.2 m, distance between rear wheel and vehicle center of gravity l _r = 1.3 m, tread l _t = 1.48 m, tire 205 / 55R16. The control weighting factors were r ₁ = 7 × 10 ⁵ , r ₂ = 5 × 10 ² , and r ₃ = 10.

To compare the effect of the method of the present invention chose the feedback control of the deviation between each target value of the conventional control law yaw rate as shown in the following equation as M _p and side slip velocity (the proportional control).
Here, K ₁ and K ₂ are gains with respect to deviations between the yaw rate and the target value of the side slip velocity, respectively.

Moreover, beta = order -V y _/ V _x a is the variation width generally V _x has a certain constant speed is small, beta Feedback V _y feedback can be regarded as equivalent to the control. In Non-Patent Documents 1 to 4, the side slip angle β feedback is used, but hereinafter, the side slip velocity V _y feedback equivalent to this is used as the conventional control. As each gain, a gain that minimizes Equation 21 as an evaluation function formula within a range in which a problem such as a vibration of the yaw rate response of the vehicle does not occur. Specifically, K ₁ = 8 × 10 ⁴ and K ₂ = 2500.

  In the simulation, in order to evaluate the yaw rate followability, the steering of a sine wave having a magnitude of 2π / 3 and a frequency of 0.5 Hz was given for one cycle from a straight traveling at an initial speed of 100 [km / h]. This steering is for steering the vehicle to make a lane change motion, and it is assumed that obstacles are avoided during high-speed driving.

  Next, the optimum value of the constant κ is obtained. A change in the value of Formula 21 which is an evaluation function equation when κ is changed by simulation was examined to obtain a value of κ that minimizes the evaluation function. The result was κ = 3.9.

  As described above, since all the conditions were determined, simulation was performed for 3 seconds. The results are shown in FIGS. 2 shows the control input, FIG. 3 shows the yaw rate response, and FIG. 4 shows the side slip angle response. As for the value of the evaluation function, the value of Equation 21 as an evaluation function expression is J, and as its breakdown, the term of the square of the deviation of the yaw rate is J1, the term of the square of the deviation of the side slip velocity is J2, and the term of energy consumption by control is J3. (J = J1 + J2 + J3).

As a result, in the control using the optimal control law of Formula 23 of the present invention, J, J1, J2, and J3 are as follows.
J = -2198, J1 = 1062, J2 = 1102, J3 = -4362

On the other hand, in the control using the conventional proportional control law of Equation 42, J, J1, J2, and J3 are as follows.
J = -1906, J1 = 639, J2 = 1081, J3 = -3626

  From the above results, the present invention is superior in energy regeneration as compared with the conventional proportional control.

  The control of the present invention uses the first term of Equation 23 instead of the conventional side slip speed, and is a term that plays a role in improving stability. Compared with the conventional side slip speed feedback, The superiority of this control becomes clear.

  A comparison of the time waveforms of the first term of Formula 23, which is the control law of the present invention, and the second term of Formula 42, which is the conventional control law, is as shown in FIG. 5, and the control law of the present invention is changed to the conventional control law. It is clear that the phase lag with respect to steering is small.

In vehicle motion control, the side slip velocity (or side slip angle) is generally estimated from the yaw rate and lateral acceleration, and drift is likely to occur because integration is the main component, so reduce this drift. If a filter is used, a phase error occurs. For this reason, even when presently performing side slip angle feedback, it is assumed that noise such as drift is included, and the magnitude of the feedback gain is limited. Therefore, the robust performance when the drift term is included in the side slip velocity is important. 6 is a comparison of the evaluation function J in the case where there is a drift term in the side slip velocity V _y. Compared with the conventional control law, the control law of this invention can confirm that the robustness in the case where a drift term is included in the side slip velocity signal is greatly improved.

  Hereinafter, an example in which the control device of the present invention is applied to a four-wheel independent control type electric vehicle having a drive device capable of independently controlling the driving force of each wheel of the vehicle as a yaw moment generating mechanism will be described in detail. FIG. 7 shows an example applied to an in-wheel motor type electric vehicle capable of independently controlling the braking / driving force of four wheels. Steering angle sensor 1, yaw rate sensor 2, G sensor 3 for detecting longitudinal acceleration of the vehicle body, accelerator opening sensor 4, each wheel speed sensor 5, which are state sensors for measuring a vehicle state quantity by a yaw moment generation mechanism, The motor drive current signal 6 enters the controller 7. The controller 7 performs feedback control based on the control law of the present invention. The output of the controller 7 enters the inverter 8, and the current adjusted here enters each wheel motor 9 to drive the tire. A large-capacity battery or a fuel cell 10 is installed as a power source, and a capacitor 11 is placed in order to cope with a current command that changes rapidly. The controller 7 calculates the driving force requested by the driver from each wheel torque command value expressed by the equations 38 to 41 and the accelerator opening signal, and adds the torque command value allocated as the motor driving torque for each wheel. And output. Note that the calculation content of the controller 7 derives the control law from Equations 9 and 10 derived from, for example, Fiala's theory.

Moreover, although the vehicle mounting status of the system is the same as in FIG. 7, the calculation content of the controller may be as follows. That is, in the above example, the control law is derived from Equations 9 and 10 derived from Fiala's theory, but the control law may be derived from a tire characteristic equation based on Magic Formula. More specifically, a function that approximates the lateral force generated by the tire from the tire characteristic equation by Magic Formula is given by the following equation.
Here, C and B are constants. Therefore, according to Magic Formula, the following equation holds.

  As described above, Expression 44 can be used instead of Expression 25. Other calculations are the same as in the case of the above-described Fiala.

  Next, in the vehicle motion control device of the present invention, a case where the mechanism for generating the yaw moment is an active suspension capable of independently controlling each wheel of the vehicle will be described. The existing active suspension mechanism is aimed at improving the ride comfort and improving the ground contact of each tire. In the present invention, this active suspension mechanism is used to improve the exercise performance by optimally controlling the load of the four wheels. In the active suspension mechanism, it is not preferable that the vehicle vibrates by applying a control input, and the stroke of the suspension is limited. Based on such assumptions, a vehicle model for obtaining a control law is defined as shown in FIG. 8, and restrictions as shown in FIG. The relationship between the lateral force and the tire load is shown in FIG. In the vehicle motion control device of the present invention for the active suspension, the tire load is controlled to improve the maneuverability and stability.

As the control law for the active suspension, when using mathematical expressions similar to the above-described evaluation function expression (21) and functional function (22), the control law, that is, the load increase (load movement) by the actuator of the active suspension is It is given by
It is.
Where l _f is the distance between the center of gravity of the vehicle and the front wheel, l _r is the distance between the center of gravity of the vehicle and the rear wheel, μ is the friction coefficient between the road surface and the tire, W _i is the load of each wheel, a is a constant, Γ _i , Θ _i is given by the following equation.
However, Y _i is a function that approximates the lateral force generated by each tire of Y ₁ being the left front wheel, Y ₂ being the right front wheel, Y ₃ being the left rear wheel, and Y ₄ being the right rear wheel.

Note that brackets of the first term on the right side of the U _A means a tire lateral force of the front wheels when without control input, the first parentheses of the right side third term means a lateral velocity of the front wheels, brackets Means the partial differentiation of the front wheel tire lateral force by the yaw rate. Further, the rear wheels when brackets of the first term on the right side of the U _B means a tire lateral force of the front wheels when adding unit control input, brackets on the right side second term plus a unit control input Means the tire lateral force.

  Further, the first term on the right side of Formula 45 is a term derived from the partial differentiation of the tire dissipating power due to the yaw rate, which causes yaw damping and improves the stability.

A function approximating the lateral force generated by each tire is given by the following tire characteristic equation derived from the Magic Formula theory.
Here, β _i is a side slip angle, and C and B are constants.

In order to evaluate the control law described above, a simulation was performed. The initial speed was 100 [km / h], and a sine wave steering with a magnitude of π / 2 and a frequency of π was given for one cycle. The torque command was 0 [Nm]. The weighting factors were r ₁ = 1.0 × 10 ⁴ , r ₂ = 5.0, and r ₃ = 0.1, respectively.

  Next, the optimum value of the constant κ is obtained. A change in the value of Formula 21 which is an evaluation function equation when κ is changed by simulation was examined to obtain a value of κ that minimizes the evaluation function. The result was κ = −0.9.

To compare the effect of the method of the present invention chose the feedback control of the deviation between each target value of the formula yaw rate and side slip velocity is a conventional comparison control shown as control law M _p of.
Here, K ₁ = 100 and K ₂ = 7.0 × 10 ⁵ .

As described above, since all the conditions were determined, simulation was performed for 3 seconds. The results are shown in FIGS. FIG. 10 shows the control input, FIG. 11 shows the yaw rate response, and FIG. 12 shows the side slip angle response. As for the value of the evaluation function, the value of Equation 21 which is the evaluation function expression is J, and as its breakdown, the square term of the deviation of the yaw rate is J1, and the square term of the deviation of the side slip velocity is J2. J3, which is a term of energy consumption by control, is necessary for obtaining a control law, but is omitted because it is not important for evaluating performance. Note that J = J1 × r ₁ + J2 × r ₂ .

As a result, in the control using the optimal control law of Formula 45 of the present invention, J, J1, and J2 are as follows.
J = 59.65, J1 = 0.0042, J2 = 3.53

On the other hand, in the conventional control according to Equation 49, J, J1, and J2 are as follows.
J = 60.25, J1 = 0.0041, J2 = 3.85

When there was no control input, J, J1, and J2 were as follows.
J = 167.50, J1 = 0.160, J2 = 1.52

  From the above results, the present invention obtained a smaller evaluation function value than the conventional control. Further, the side slip angle was suppressed from 1.2 seconds to 2.5 seconds.

  Hereinafter, an example in which the above-described control device of the present invention is applied to an active suspension capable of independently controlling each wheel of a vehicle using a yaw moment generation mechanism will be specifically described. FIG. 13 shows an example in which the present invention is applied to a control device for an electro-hydraulic active suspension capable of independently controlling a four-wheel suspension mechanism. Signals from the sprung acceleration sensor 21, the unsprung acceleration sensor 22, the suspension stroke sensor 23, and the suspension transmission force sensor 24, which are state sensors that measure the state amount of the vehicle by the yaw moment generation mechanism, enter the control circuit 25. The control circuit 25 performs feedback control based on the control law of the present invention, and the output of the control circuit 25 enters the inverter 26 and the regenerative circuit 27. The signal that enters the inverter 26 is the calculation result of the control law of Formula 45. The signal entering the regenerative circuit 27 is a signal for determining the regenerative mode and the power running mode of the motor 28 and issuing a necessary boost command. The motor 28 drives the hydraulic pump 29.

  Note that the vehicle motion control device of the present invention is not limited to the illustrated examples described above, and it is needless to say that various changes can be made without departing from the scope of the present invention.

FIG. 1 is a three-degree-of-freedom vehicle motion model in the vehicle motion control device of the present invention. FIG. 2 is a simulation comparison graph of time waveforms of control inputs for control and conventional control in the vehicle motion control apparatus of the present invention. FIG. 3 is a simulation comparison graph of yaw rate followability for control, conventional control, and no control in the vehicle motion control device of the present invention. FIG. 4 is a simulation comparison graph of the time waveform of the side slip angle for control, conventional control, and no control in the vehicle motion control device of the present invention. FIG. 5 is a simulation comparison graph of time waveforms of the first term of the control law number 23 and the second term of the conventional control law number 42 in the vehicle motion control device of the present invention. FIG. 6 is a comparison graph of the evaluation function J in the case where there is a drift term in the side slip speed, for the control in the vehicle motion control device of the present invention and the conventional control. FIG. 7 is a diagram illustrating a situation in which the control law in the vehicle motion control device of the present invention is mounted on an electric vehicle. FIG. 8 is a vehicle motion model representing the relationship between the tire load and the control input in the vehicle motion control device of the present invention. FIG. 9 is a graph showing the relationship between the lateral force and the tire load. FIG. 10 is a simulation comparison graph of time waveforms of control inputs for the control and the conventional control in the vehicle motion control device of the present invention. FIG. 11 is a simulation comparison graph of yaw rate responses for control, conventional control, and no control in the vehicle motion control apparatus of the present invention. FIG. 12 is a simulation comparison graph of the response of the side slip angle for the control, the conventional control, and no control in the vehicle motion control apparatus of the present invention. FIG. 13 is a diagram illustrating a situation in which the control law in the vehicle motion control device of the present invention is mounted on a vehicle having an active suspension mechanism.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Steering angle sensor 2 Yaw rate sensor 3 G sensor 4 Accelerator opening sensor 5 Wheel speed sensor 6 Motor drive current signal 7 Controller 8 Inverter 9 In-wheel motor 10 Battery 11 Capacitor 21 Sprung acceleration sensor 22 Unsprung acceleration sensor 23 Suspension stroke sensor 24 Suspension transmission force sensor 25 Control circuit 26 Inverter 27 Regenerative circuit 28 Motor 29 Hydraulic pump

Claims (13)

A vehicle motion control device for controlling the motion of a vehicle, the vehicle motion control device comprising:
A yaw moment generating mechanism for generating a yaw moment in the vehicle;
A state sensor for measuring a vehicle state quantity by the yaw moment generation mechanism;
Control means for performing feedback control in consideration of a ratio of dissipated power, which is a heat loss per unit time generated by slipping of a running tire with respect to a vehicle state quantity measured by the state sensor;
A vehicle motion control device comprising: 2. The vehicle motion control apparatus according to claim 1, wherein the control means includes a term of the following equation in its control law:
Is,
A vehicle motion control device.   3. The vehicle motion control device according to claim 1, wherein the state quantity of the vehicle is a yaw rate.   3. The vehicle motion control apparatus according to claim 1, wherein the state quantity of the vehicle is a side slip speed or a side slip angle. 4. The vehicle motion control device according to claim 1, wherein the dissipative power is approximated by the following equation:
_T1 , _dT2 , and _dT3 are given by the following equations:
However, S ₁ is the left front wheel, S ₂ is the right front wheel, S ₃ is the left rear wheel, S ₄ is a function approximating the lateral force generated by each tire of the right rear wheel, δ is the front wheel steering angle, l _f is the distance between the vehicle center of gravity and the front wheels, l _r is the distance between the vehicle center of gravity and the rear wheels, and l _t is the tread.
A vehicle motion control device.   The vehicle motion control device according to claim 1, wherein the yaw moment generation mechanism includes a drive unit capable of independently controlling a driving force of each wheel of the vehicle. 7. The vehicle motion control apparatus according to claim 6, wherein the control means has a control law given by the following equation:
Where κ is a constant, r _i is a weighting factor, V _x is the longitudinal speed of the vehicle, and V _y is the side slip speed of the vehicle.
Where F _ix and F _iy are centrifugal forces acting on the vehicle, S ₁ is the left front wheel, S ₂ is the right front wheel, S ₃ is the left rear wheel, and S ₄ is the lateral force generated by each tire of the right rear wheel. Δ is the front wheel steering angle, l _f is the distance between the vehicle center of gravity and the front wheels, l _r is the distance between the vehicle center of gravity and the rear wheels, and l _t is the tread.
A vehicle motion control device. The vehicle motion control device according to claim 7, wherein a function that approximates the lateral force generated by each tire is given by the following tire characteristic equation derived from Fiala's theory:
However,
Where K is the tire cornering power, W _i is the load of each wheel, μ is the friction coefficient between the road surface and the tire, and β _i is the side slip angle.
A vehicle motion control device. 8. The vehicle motion control device according to claim 7, wherein a function that approximates the lateral force generated by each tire is given by the following tire characteristic equation derived from Magic Formula theory:
Where W _i is the load of each wheel, μ is the coefficient of friction between the road surface and the tire, β _i is the side slip angle, and C and B are constants,
A vehicle motion control device.   The vehicle motion control device according to claim 1, wherein the yaw moment generation mechanism includes active suspension means capable of independently controlling each wheel of the vehicle. 11. The vehicle motion control apparatus according to claim 10, wherein the control means is given by the following equation as a control law:
That is,
Where l _f is the distance between the center of gravity of the vehicle and the front wheel, l _r is the distance between the center of gravity of the vehicle and the rear wheel, μ is the friction coefficient between the road surface and the tire, W _i is the load of each wheel, a is a constant, Γ _i , Θ _i is given by:
However, Y _i is a function that approximates the lateral force generated by each tire of Y ₁ being the left front wheel, Y ₂ being the right front wheel, Y ₃ being the left rear wheel, and Y ₄ being the right rear wheel.
A vehicle motion control device. 12. The vehicle motion control apparatus according to claim 11, wherein a function approximating the lateral force generated by each tire is given by the following tire characteristic equation derived from Magic Formula theory:
Where β _i is a side slip angle, C and B are constants,
A vehicle motion control device.   2. The vehicle motion control device according to claim 1, wherein the yaw moment generating mechanism includes a steering control means capable of controlling a steering angle of the vehicle.