JP2017206116A - Driving assistance control device using electric power steering mechanism, and vehicle on which driving assistance control device is mounted - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a driving assistance control device using an electric power steering mechanism for compensating for a reduction in stability caused by a driving condition and felt by a driver and reducing a steering operation load during a normal steering operation, and a vehicle on which the driving assistance control device is mounted.SOLUTION: The driving assistance control device is provided with at least one of a vehicle zero-point characteristic compensation unit that compensates for a current command value so as to make vehicle characteristics from a steering angle to a yaw rate similar to primary delay characteristics, a steering information characteristic compensation unit that compensates for the current command value so that the time constant of steering information characteristics from vehicle behavior information to steering information may become a desired value, and a vehicle attenuation characteristic compensation unit that compensates for the current command value by using angle information so that the attenuation rate of the vehicle characteristics may become approximately 1. For a vehicle in which rear-wheel cornering compliance Cr during a normal steering operation is small, a vehicle steering operation load is reduced by compensating for the current command value by at least one of the vehicle zero-point characteristic compensation unit, the steering information characteristic compensation unit, and the vehicle attenuation characteristic compensation unit.SELECTED DRAWING: Figure 7

Description

  The present invention relates to a driving support control device using an electric power steering mechanism that drives a motor based on a current command value to assist and control a steering system, and a vehicle equipped with the driving assistance control device. The present invention relates to a driving support control device using an electric power steering mechanism that compensates for a reduction in stability and reduces the load of steering driving in normal steering driving, and a vehicle equipped with the driving support control device.

  An electric power steering device that assists and controls the steering system of a vehicle with the rotational force of a motor is provided with a steering assist force (assist force) applied to a steering shaft or a rack shaft by a transmission mechanism such as a gear or a belt via a speed reducer. ). Such a conventional electric power steering apparatus performs feedback control of the motor current in order to accurately generate the torque of the steering assist force. In feedback control, the motor applied voltage is adjusted so that the difference between the current command value and the motor current detection value becomes small. In general, the adjustment of the motor applied voltage is performed by the duty of PWM (pulse width modulation) control. It is done by adjustment.

  The general configuration of the electric power steering apparatus will be described with reference to FIG. 6b is further connected to the steering wheels 8L and 8R via hub units 7a and 7b. Further, the column shaft 2 is provided with a torque sensor 10 for detecting the steering torque of the handle 1 and a steering angle sensor 14 for detecting the steering angle θ, and the motor 20 for assisting the steering force of the handle 1 is provided with the reduction gear 3. Are connected to the column shaft 2 via The control unit (ECU) 30 that controls the electric power steering apparatus is supplied with electric power from the battery 13 and also receives an ignition key (IG) signal via the ignition key 11. The control unit 30 calculates a current command value of an assist (steering assistance) command based on the steering torque Ts detected by the torque sensor 10 and the vehicle speed V detected by the vehicle speed sensor 12, and compensates the current command value. The current supplied to the motor 20 is controlled by the voltage control command value Vref subjected to.

  The steering angle sensor 14 is not essential and may not be provided, and the steering angle can be obtained from a rotation sensor such as a resolver connected to the motor 20.

  The control unit 30 is connected to a CAN (Controller Area Network) 40 that exchanges various types of vehicle information, and the vehicle speed V can also be received from the CAN 40. The control unit 30 can be connected to a non-CAN 41 that exchanges communications, analog / digital signals, radio waves, and the like other than the CAN 40.

  The control unit 30 is mainly composed of an MCU (including a CPU, an MPU, etc.). FIG. 2 shows general functions executed by a program inside the MCU.

  The function and operation of the control unit 30 will be described with reference to FIG. 2. The steering torque Ts detected by the torque sensor 10 and the vehicle speed V detected by the vehicle speed sensor 12 (or from the CAN 40) are represented by the current command value Iref 1. The current command value calculation unit 31 to be calculated is input. The current command value calculation unit 31 calculates a current command value Iref1, which is a control target value of the motor current supplied to the motor 20, using an assist map or the like based on the input steering torque Ts and the vehicle speed V. The current command value Iref1 is input to the current limiting unit 33 via the adding unit 32A, and the current command value Irefm with the maximum current limited is input to the subtracting unit 32B, and the deviation ΔI (= Irefm−Im) is calculated, and the deviation ΔI is input to a PI (proportional integration) control unit 35 for improving the characteristics of the steering operation. The voltage control command value Vref whose characteristics are improved by the PI control unit 35 is input to the PWM control unit 36, and the motor 20 is PWM driven via an inverter 37 as a drive unit. The motor current value Im of the motor 20 is detected by the motor current detector 38 and fed back to the subtraction unit 32B. The inverter 37 uses a field effect transistor (FET) as a drive element, and is configured by a bridge circuit of the FET.

  A compensation signal CM from the compensation signal generator 34 is added to the adder 32A, and the compensation of the steering system system is performed by adding the compensation signal CM to improve the convergence and inertia characteristics. . The compensation signal generator 34 adds the self-aligning torque (SAT) 34-3 and the inertia 34-2 by the adder 34-4, and further adds the convergence 34-1 to the addition result by the adder 34-5. The addition result of the adder 34-5 is used as the compensation signal CM.

  Such an electric power steering device can be positioned as a driving support control device, and can be used to assist steering driving and reduce steering driving load.

  Although the effect of reducing the steering operation burden in a state where ordinary roads are normally steered (normal steering operation) is indirect, it is positioned as an important technology in traffic safety along with accident avoidance technology. ing. Steering driving in normal steering driving refers to steering control that follows a target trajectory recognized by the driver. In this case, the driver's steering driving action is performed by recognition, judgment, and action. Therefore, in the reduction of steering driving burden, it corresponds to recognition, judgment, and action, (1) power assist characteristics that can reduce the physical burden associated with steering action, (2) vehicle characteristics that are easy to perform steering control, and (3) vehicle behavior. Steering information (steering information such as steering torque) that can be easily grasped by steering information characteristics (hereinafter collectively referred to as “steering characteristics”), and target characteristics and realization of each characteristic Means are discussed. Here, the steering information characteristic refers to a characteristic from information representing the behavior of the vehicle such as a yaw rate (vehicle behavior information) to steering information.

  The electric power steering apparatus plays a role in many vehicles for reducing the physical burden associated with the steering action (1).

  Regarding the vehicle characteristics that are easy to control by steering in (2), discussions have been made based on the stability of the characteristic equation that is the pole of the transmission characteristics that have the actual steering angle as input and the vehicle behavior as output. For example, in Non-Patent Document 1, the time constant condition for approximating the response characteristics of the yaw rate and the lateral acceleration with the first-order lag characteristics to obtain a response characteristic with good feeling, and the time constant of the steering torque characteristic with good feeling And the relationship between the time constants of the response characteristics. Further, as a means for realizing vehicle characteristics that are easy to perform steering control, for example, in Non-Patent Document 2, after avoiding the constraint that the tire and the handle are mechanically coupled using 4WS (four-wheel steering), From the viewpoint of the steering response characteristics of the yaw rate and lateral acceleration, a vehicle characteristic compensation method using state feedback and a compensation method using control for a reference model have been proposed.

  For the characteristics of (3) where the vehicle behavior can be easily grasped by the steering information, the relationship between the steering torque, the yaw rate and the lateral acceleration is represented by a Lissajous waveform (sometimes called Lissajous figure, Lissajous curve, etc.), and its shape and subjective Discussion based on the correlation with the evaluation of steering feeling. For example, in Non-Patent Document 3, the relationship between the steering torque and the lateral acceleration is represented by a Lissajous waveform, and the driver's senses are classified into responsive feeling, steering wheel return feeling, and steering torque phase lag feeling, and characteristics corresponding to each sense. The way of value is presented. In the discussion of the means for realizing the characteristics that make it easy to grasp the vehicle behavior with the steering information, the driver recognizes the vehicle behavior not only with the visual information but also with the steering torque information. Analysis shows that the characteristic equation of vehicle characteristics related to vehicle stability is not included in the transfer characteristic, so there is a vehicle condition where the driver cannot feel a sense of stability even if the vehicle behavior is stable. The problem that it is difficult to grasp the vehicle behavior by the steering torque information is expected, and there is a research suggesting this (for example, Non-Patent Document 4).

Hiroaki Fujinami, two others, “About the relationship between steering characteristics and driver feeling”, Automobile Society of Japan Academic Lecture Preprints 951, Japan Society of Automotive Engineers, May 1995, p. 181-184 Masato Abe, Hiroshi Osawa, “Automotive performance improvement technology for automobiles (spread version)”, Asakura Shoten, August 2008, p. 114-125 Hirofumi Sato, 2 others, “Study of steering response characteristics related to steering feeling”, Automobile Engineering Society Proceedings, Japan Automobile Engineering Society, March 1990, Vol. 44, No. 3, p. 52-58 Daisuke Yamada and two others, “Effect of characteristics of steering torque on human-car system”, Proceedings of the Society of Automotive Engineers, Japan Society for Automotive Engineers, March 2013, Vol. 44, No. 2, p. 459-465

  However, in Non-Patent Document 1 and Non-Patent Document 2, it is easy to grasp the technical content related to the vehicle characteristic (2) that is easy to perform steering control, and in Non-Patent Document 3 and Non-Patent Document 4, it is easy to grasp the vehicle behavior (3) from the steering information. Although the technical contents related to the characteristics are presented, the technology is not compatible with both (2) and (3). In addition, regarding the problem that there is a vehicle condition in which the driver cannot feel a sense of stability even if the vehicle behavior in (3) is stable, the generation mechanism has not been analyzed, and specific countermeasures have been discussed. Absent. In addition, this problem is a problem of the interface between the vehicle and the driver, so it is considered to be an issue that should be compensated for by steering. In particular, the effect of this problem is great in vehicles with a low degree of freedom in vehicle design.

  The present invention has been made under the circumstances as described above, and the object of the present invention is to analyze the occurrence mechanism of the phenomenon that the driver cannot feel a sense of stability even if the vehicle behavior is stable, and depending on the vehicle conditions. An object of the present invention is to provide a driving support control device using an electric power steering mechanism that compensates for the reduction in stability felt by the driver and reduces the load of steering driving in normal steering driving, and a vehicle equipped with the driving support control device.

  The present invention relates to a driving support control apparatus using an electric power steering mechanism that drives a motor based on a current command value to assist and control a steering system. The object of the present invention is to provide vehicle characteristics from a steering angle to a yaw rate. A vehicle zero point characteristic compensator for compensating the current command value so as to approximate a first order lag characteristic, and the current command value so that a time constant of the steering information characteristic from the vehicle behavior information to the steering information becomes a desired value. At least one of a steering information characteristic compensation unit that compensates and a vehicle damping characteristic compensation unit that compensates the current command value using angle information so that an attenuation rate of the vehicle characteristic becomes approximately 1, For a vehicle having a small rear wheel cornering compliance Cr in normal steering operation, at least the vehicle zero point characteristic compensation unit, the steering information characteristic compensation unit, and the vehicle damping characteristic compensation unit By compensating the current command value by one, it is achieved by reducing the burden of steering operation of the vehicle.

  In addition, the object of the present invention is to provide a vehicle zero point characteristic compensation unit that compensates the current command value so that the vehicle characteristic from the steering angle to the yaw rate approximates the first order lag characteristic, and steering from the vehicle behavior information to the steering information. A steering information characteristic compensator that compensates the current command value so that the time constant of the information characteristic becomes a desired value, and has a small rear wheel cornering compliance Cr in a normal steering operation and a neutral steering characteristic; This is achieved by reducing the burden of steering operation of the vehicle by compensating the current command value by at least one of the vehicle zero point characteristic compensation unit and the steering information characteristic compensation unit. .

  Further, the object of the present invention is to provide the vehicle zero point characteristic compensation unit having a pole that cancels out the zero point of the vehicle characteristic, and the characteristic by the torsion bar and the vehicle zero point characteristic compensation unit is equal to the pole of the vehicle characteristic. By performing pole-zero cancellation so that the vehicle characteristic is approximated to a first-order lag characteristic, or the vehicle behavior information is a yaw rate, and the steering information is a steering torque, Alternatively, the steering information characteristic compensation unit compensates the current command value using a self-aligning torque, or the vehicle damping characteristic compensation unit uses a steering angle as the angle information, or the rear Wheel cornering compliance Cr is the vehicle wheelbase L, front axle center-of-gravity point distance Lf, rear axle center-of-gravity point distance Lr, weight For M, yaw moment of inertia Ym and vehicle speed V, when the following formula 1 is satisfied, if the rear wheel cornering compliance Cr is small, or if the steering frequency is about 0.5 Hz or less, This is achieved more effectively.

Further, the above object is achieved by a vehicle equipped with a driving support control device using the electric power steering mechanism.

  According to the driving support control apparatus using the electric power steering mechanism of the present invention, the vehicle characteristics are substantially reduced by utilizing the analysis result of the phenomenon that the driver cannot feel a sense of stability even if the vehicle behavior is stable. By compensating the current command value so that the time constant of the steering information characteristic has a desired value so as to approximate the first-order lag characteristic with a damping factor of 1, the degree of freedom in vehicle design as in a small and medium-sized vehicle Even in a vehicle with a small number of vehicles, it is possible to improve the sense of stability felt by the driver and reduce the steering operation load during normal steering operation. In addition, by mounting the driving support control device on a vehicle, a sense of stability is improved and traveling with a reduced load becomes possible.

It is a lineblock diagram showing an outline of an electric power steering device. It is a block diagram which shows the structural example of the control unit (ECU) of an electric power steering apparatus. It is a block diagram which shows the simulation model which can reproduce a steering characteristic. It is a characteristic view which shows the power assist characteristic used with a simulation model. It is a Lissajous waveform showing a steering torque characteristic when a steering operation is simulated using a simulation model. (A) is when the vehicle speed is 80 km / hour and the steering frequency is 0.3 Hz, (B) is when the vehicle speed is 80 km / hour and the steering frequency is 0.5 Hz, and (C) is when the vehicle speed is 120 km / hour and the steering frequency. (D) is a Lissajous waveform when the vehicle speed is 120 km / hour and the steering frequency is 0.5 Hz. It is a Bode diagram which shows the change of the gain and phase of a SAT transfer function with respect to a steering frequency. (A) is a Bode diagram showing a change in gain, and (B) is a Bode diagram showing a change in phase. It is a block diagram which shows the structural example (1st Embodiment) of this invention. It is an image figure which shows the mode of the torque generate | occur | produced between a road surface and a steering. It is a block diagram which shows the structural example of the state feedback control for adjusting a yaw rate attenuation factor. (A) is a block diagram showing a configuration example when the yaw rate is fed back, and (B) is a block diagram showing a configuration example equivalent to (A). It is a block diagram which shows the structural example for performing SAT estimation. (A) is a block diagram showing a configuration example when SAT estimation is performed using an external observer, and (B) is a block diagram showing a configuration example equivalent to (A) when the SAT estimation value and the actual SAT match. FIG. It is a flowchart which shows the operation example (1st Embodiment) of this invention. It is the schematic which shows the driving | running | working course used in order to confirm the effect of this invention. It is a graph which shows the change of the yaw rate and steering torque when not performing with compensation of the present invention. (A) is a graph when compensation is not performed, and (B) is a graph when compensation is performed. It is a block diagram which shows the structural example (2nd Embodiment) of this invention. It is a flowchart which shows the operation example (2nd Embodiment) of this invention. It is a block diagram which shows the outline | summary of the vehicle carrying the driving assistance control apparatus of this invention, 4WS, and a variable gear ratio mechanism. It is a block diagram which shows the structural example (3rd Embodiment) of this invention.

  In the present invention, on the premise that the power assist characteristic that can reduce the physical burden associated with the steering action is already realized among the steering characteristics, the steering characteristics that make it easy to grasp the vehicle characteristics and the vehicle behavior that are easy to control by steering information. Information characteristics are realized using an electric power steering mechanism (EPS). Of these, regarding the steering information characteristic, the driver uses the steering torque information when recognizing the vehicle behavior, so the characteristic of the steering torque with respect to the vehicle behavior (hereinafter referred to as “steering torque characteristic”) is the main target. Yes.

  In realizing the above, the target characteristic of the steering torque characteristic is that it can be approximated by a primary transmission characteristic having a time constant that matches the driver characteristic in normal steering operation. This is because the steering torque information plays an important role in the on-center region and off-center region, which are normal steering driving situations, but the power assist amount is adjusted outside the off-center region. A simple function with reduced sensitivity, the relative importance of steering torque information with respect to visual information and steering angle information, and reproducibility of steering torque characteristics and easy understanding of vehicle behavior This is derived from the fact that it is desirable that the vehicle behaves in the expected amount after the driver feels the steering torque. The As the vehicle behavior information representing the vehicle behavior, the yaw rate is used. Further, the yaw rate characteristic with respect to the steering angle (hereinafter referred to as “yaw rate transmission characteristic”) is used as the vehicle characteristic. As the vehicle behavior information, lateral acceleration may be used instead of the yaw rate.

  In order for the steering torque characteristic to achieve the target characteristic, it is necessary to take measures against the problem that there is a vehicle condition in which the driver cannot feel a sense of stability even if the vehicle behavior is stable. For this purpose, the Lissajous waveform of the yaw rate and steering torque is measured using a simulation model that can reproduce the steering characteristics, and the conditions under which the driver feels stable are derived based on the analysis results. Hereinafter, the derivation of the condition will be described.

The simulation model is modeled including a vehicle model, a steering mechanism model, and an EPS controller, and has a configuration as shown in FIG. In FIG. 3, [theta] d is the steering angle, [theta] g is the steering angle, [theta] t is the actual steering angle, gamma is the yaw _{rate, T tor} the steering torque detection _{value, T stg} steering _{torque, T sat} is self-aligning torque (SAT), K _Tor is the torsion bar rigidity, STG (s) is the steering dynamic characteristic, g _tot is the total gear ratio, C ₁ (s) is the feed forward characteristic of the EPS controller, C ₂ (s) is the feedback characteristic of the EPS controller, G _θ (s) is a characteristic of the yaw rate with respect to the actual steering angle θt (hereinafter referred to as “actual steering angle yaw rate transmission characteristic”), G _γ (s) is a characteristic of the SAT with respect to the yaw rate γ, and the simulation model represents K _tor . A torsion bar 100, a characteristic part 101 having C ₁ (s), a characteristic part 102 having C ₂ (s), and a characteristic part having STG (s) 103, a gain unit 104 having a gain of 1 / g _tot , a characteristic unit 105 having G _θ (s), a characteristic unit 106 having G _γ (s), an addition / subtraction unit 108, and subtraction units 107 and 109. The characteristic unit 101 has a power assist characteristic as shown in FIG. 4 in addition to the function as a third-order phase compensator, and converts the steering torque detection value _Ttor into the power assist torque by the power assist characteristic. After that, phase compensation is performed. The power assist characteristic corresponds to an assist map used by the current command value calculation unit 31 in FIG. 2, but here is a characteristic that does not depend on the vehicle speed.

  The parameters of the vehicle model used in this simulation are as shown in Table 1 below. The identified vehicle is a small passenger car with an engine displacement of 1.2 liters and a vehicle having an understeer characteristic with a stability factor of 0.0017. is there.

For the above simulation model, at a vehicle speed of 80 km / h and 120 km / h, a steering angle θd that changes in a sweep sine wave shape in a range of 10 ° to 90 ° is input at a steering frequency of 0.3 Hz and 0.5 Hz, respectively. FIG. 5 shows a Lissajous waveform of the steering torque characteristic (the characteristic of the steering torque T _stg with respect to the yaw rate γ). The reason for using 0.3 Hz and 0.5 Hz as the steering frequency is as follows. That is, it is known that the steering operation controllability of following the target trajectory is important in normal steering operation, and the follow-up control with respect to the target trajectory has a frequency characteristic upper limit by adapting the ability of the driver. For example, in the crossover theory, the driver corrects the vehicle dynamic characteristics to adapt to the follow-up control response of about 0.6 Hz, and there is another report of 0.4 Hz. Therefore, it is assumed that the steering frequency in the normal steering operation is approximately 0.5 Hz or less, and 0.3 Hz and 0.5 Hz that are within the range are used.

  5A, FIG. 5A shows a case where the vehicle speed is 80 km / hour and the steering frequency is 0.3 Hz, and FIG. 5B shows a case where the vehicle speed is 80 km / hour and the steering frequency is 0.5 Hz. ) Shows a Lissajous waveform when the vehicle speed is 120 km / hour and the steering frequency is 0.3 Hz, and FIG. 5D shows a Lissajous waveform when the vehicle speed is 120 km / hour and the steering frequency is 0.5 Hz. As can be seen from FIGS. 5A and 5B, at a vehicle speed of 80 km / hour, the hysteresis width at the yaw rate near zero increases at a steering frequency of 0.5 Hz rather than the steering frequency of 0.3 Hz. Increases further with the amplitude of the yaw rate. Since the yaw rate in the off-center region is approximately 1 to 15 ° / second, the steering torque gain with respect to the yaw rate in the range of ± 10 ° / second in the off-center region decreases as the yaw rate amplitude increases. From this result, it is estimated that the yaw rate is difficult to grasp by the steering torque. Further, when looking at the simulation result at a vehicle speed of 120 km / hour shown in FIGS. 5C and 5D, the hysteresis width near the zero yaw rate is narrower at the vehicle speed of 120 km / hour than at the vehicle speed of 80 km / hour. It can be seen that the hysteresis width becomes narrower as the yaw rate amplitude and steering frequency increase. Although it is a well-known phenomenon that the hysteresis width becomes narrower and the steering feeling becomes unreliable at higher speeds, the yaw rate attenuation rate in this simulation is about 0.7, which is a stable category. That is, even if the vehicle characteristics are stable and the vehicle behavior is stable, (a) the hysteresis width changes with respect to the amplitude or steering frequency of the yaw rate, and (b) the hysteresis width near zero of the yaw rate according to the vehicle speed. It can be seen that when the phenomenon of narrowing occurs, the sense of stability felt by the driver may be lost. Therefore, the cause of these two phenomena will be described.

First, assuming that the steering dynamic characteristic is constant, when using a two-wheeled model using a linear tire model as a vehicle model and using a SAT as a substitute characteristic of the steering torque, SAT T _sat ( The transfer function of s) (hereinafter referred to as “SAT transfer function”) is expressed by the following formula 2.

Where ξ is trail (cast rail), Yf (s) is front tire lateral force, θt (s) is actual steering angle, M is vehicle weight, Ym is yaw moment of inertia, Kr is rear tire cornering power, Lr is The distance between the rear axle centroid points, L is the wheel base, Cr is the rear cornering compliance, T ₁ is the time constant, and s is the Laplace operator. Equation 2 is a basic formula of a plane two-wheel model (for example, Masato Abe, Hiroshi Osawa, “Technology for improving motor performance (popular version)”, Asakura Shoten, August 2008, p. 21-36), On the other hand, the following equations 3 and 4 that approximately represent the equations of motion in the lateral direction and the yaw direction, and SAT is the moment around the kingpin obtained by multiplying the front tire lateral force by the trail. It is calculated by applying what is expressed.

Here, α (s) is the lateral acceleration, Yr (s) is the rear tire lateral force, and Lf is the distance between the front axle center points. The natural frequency ω _{zn of} the zero point, the attenuation factor ζ _z of the zero point, and the natural frequency ω _{pn of the} pole of the SAT transfer function of Equation 2 are expressed by the following _Equations 6, 7, and 8, respectively.

When the number 2 of the SAT transfer function is represented by a Bode diagram, it is as shown in FIG. FIG. 6 shows changes in the gain and phase of the SAT transfer function when the steering frequency is changed at vehicle speeds of 60 km / h, 80 km / h, 100 km / h, and 120 km / h. FIG. A change in gain is shown, and FIG. 6B shows a change in phase. According to FIG. 6, in the region where the steering frequency is 0.5 Hz or less, the gain of the SAT transfer function increases as the vehicle speed increases, and the phase advance amount decreases. At a vehicle speed of 120 km / h, the phase lag characteristic is shown between 0.2 and 1 Hz, and as a result, the yaw rate amplitude and the steering frequency as shown in FIGS. Therefore, it is estimated that the phenomenon that the hysteresis width is narrowed occurs. This phase lag characteristic is a result of the fact that the natural frequency ω _{pn of the} pole expressed by _{Equation 8} is lower than the natural frequency ω _{zn of the} zero point expressed by _Equation 6. This is because the decrease in the phase advance amount due to the vehicle speed of the SAT transfer function occurs even when the zero point attenuation rate ζ _z expressed by Equation 7 is decreased according to the vehicle speed, but this does not lead to the phase delay characteristic. . As can be seen from Equation 6, the natural frequency ω _zn of the zero point is a constant obtained from the specifications of the vehicle, and increases as the rear axle cornering compliance Cr decreases. Further, as can be seen from Equation 8, the natural frequency ω _pn of the pole is an inverse function of the vehicle speed with the inverse of the rear cornering compliance Cr as a coefficient, and decreases as the vehicle speed increases, and the rear cornering compliance Cr Is larger, the frequency becomes lower than the natural frequency ω _zn at the zero point at a lower vehicle speed, and the SAT transfer function partially has a phase delay characteristic. That is, even if the stability of the vehicle characteristics is ensured, the hysteresis width is narrowed according to the vehicle speed, and the states (a) and (b) described above are obtained. Therefore, in order for the driver to feel a sense of stability, it is necessary to satisfy the following formula 9 in the normal steering operation. For this purpose, the rear axle cornering compliance Cr should be a small value that satisfies the following formula 10. I need it.

As a condition for the driver to feel a sense of stability, a condition that the rear-shaft cornering compliance Cr is satisfied has been derived. Therefore, assuming that this condition is satisfied, the above-mentioned target characteristic of the steering torque characteristic is “the steering torque characteristic is normal steering The conditions for achieving “approximate with a primary transfer characteristic having a time constant that matches the driver characteristic in driving” will be described.

  First, conditions when the vehicle is assumed to have neutral steering characteristics will be described. The neutral steer characteristic can be defined as a characteristic in which the yaw rate attenuation rate becomes approximately 1 without depending on the vehicle speed. Under the definition, the yaw rate attenuation rate is a characteristic of the yaw rate γ (s) with respect to the actual steering angle θt (s). It is assumed that a certain actual steering angle yaw rate transmission characteristic can be approximated to a first-order lag characteristic expressed by the following formula 11 in a normal steering operation (steering frequency: 0.5 Hz or less) (hereinafter, this assumption can be approximated as “Assumption 1”). ”).

Here, τ _n is a pole time constant. Similarly to the actual steering angle yaw rate transmission characteristic, the transmission characteristic of the lateral acceleration α (s) with respect to the actual steering angle θt (s) (hereinafter referred to as “actual steering angle lateral acceleration transmission characteristic”) is expressed by the following equation (12). It is assumed that it can be approximated to the expressed primary phase characteristic (hereinafter, the assumption that this approximation is possible is referred to as “Assumption 2”).

Here, τ _α is a zero time constant. When the SAT transfer function is obtained from Equation 2, Equation 5, Equation 11, and Equation 12 under Assumption 1 and Assumption 2, the following Equation 13 is obtained, and the steering torque characteristic substituted for SAT becomes the primary transfer characteristic.

Here, τ _sat and τ ₁ are time constants, and τ _sat is obtained by the following equation (14).

τ ₁ is a time constant set to express Equation 13 with a proper transfer function (a transfer function in which the numerator order is less than or equal to the denominator order), and a value corresponding to 10 Hz is given.

If the steering torque characteristic becomes the primary transmission characteristic, the time constant τ _sat shown in _Equation 14 is set so as to match the driver characteristic (hereinafter, this setting is referred to as “time constant setting”). The steering torque characteristic can be a target characteristic.

  From the above, when the rear-shaft cornering compliance Cr in the normal steering operation is sufficiently small so as to satisfy several tens, the vehicle having the yaw rate attenuation rate of approximately 1 without depending on the vehicle speed, such as the neutral steer characteristic, is assumed 1 If Assumption 2 is established and the time constant can be set, the steering torque characteristic becomes the target characteristic.

  If the vehicle has a neutral steer characteristic, the steering torque characteristic can be set to the target characteristic if the above condition is satisfied. However, if the vehicle has an under steer characteristic, the yaw rate attenuation rate varies depending on the vehicle speed, and therefore satisfies the following equation (12). Vehicle speed is limited. Therefore, it is necessary to compensate for the vehicle having an understeer characteristic so that the yaw rate attenuation rate is approximately 1, but this compensation (hereinafter referred to as “attenuation rate compensation”) is performed by adjusting the specifications of the vehicle. It is difficult. This is because the stability factor K is expressed as a function of the rear-shaft cornering compliance Cr as shown in the following formula 15, but as can be seen from the formula 15, the stability factor K increases when the rear-shaft cornering compliance Cr is set small. This is because the understeer characteristic is strengthened.

Here, Kf is the front tire cornering power, and Cf is the front wheel cornering compliance. On the other hand, if the front wheel cornering compliance Cf is reduced, there is a problem that ordinary vehicles become sensitive to shimmy and brake judder. Therefore, it is difficult to compensate for the attenuation factor even with this method. Therefore, attenuation rate compensation is performed using a steering function.

  In the steering function, in addition to compensation for the attenuation rate, compensation for assuming Assumption 1 and Assumption 2 (hereinafter referred to as “first order approximate compensation”) and compensation for setting a time constant (hereinafter referred to as “time constant compensation”). Also). That is, the steering function performs attenuation rate compensation, first-order approximation compensation, and time constant compensation when the vehicle has an understeer characteristic, and performs first-order approximation compensation and time constant compensation when the vehicle has a neutral steer characteristic. By performing these compensations, the steering torque characteristic becomes the target characteristic, and the actual steering angle yaw rate transmission characteristic becomes a simple characteristic that approximates to the first-order lag characteristic with an attenuation factor of approximately 1, and is linked to the actual steering angle. Thus, the yaw rate transmission characteristic, which is the characteristic of the yaw rate with respect to the steering angle that changes, is also a simple characteristic, so that the vehicle characteristic is easy to perform steering control.

  In the present invention, for each of the three compensations (attenuation rate compensation, first-order approximation compensation, and time constant compensation), a compensation unit for each compensation is prepared. Specifically, a vehicle damping characteristic compensation unit is provided for attenuation rate compensation, a vehicle zero point characteristic compensation unit is provided for primary approximation compensation, and a steering information characteristic compensation unit is provided for time constant compensation. However, when the vehicle has a neutral steering characteristic, the vehicle damping characteristic compensator is not necessary. Each compensation is performed by compensating the current command value. By performing such compensation, when the rear axle cornering compliance Cr in the normal steering operation is small, the vehicle characteristics that are easy to control the steering and the steering information characteristics that make it easy to grasp the vehicle behavior by the steering information are realized. Even in a vehicle with a low degree of freedom in vehicle design, it is possible to improve the sense of stability felt by the driver and reduce the load of steering operation.

  Embodiments of the present invention will be described below with reference to the drawings. In the following embodiment, it is assumed that the target vehicle has a small rear-shaft cornering compliance Cr in the normal steering operation and satisfies the following formula (10).

  First, an embodiment (first embodiment) for a vehicle having an understeer characteristic will be described.

  FIG. 7 shows a configuration example of the first embodiment. FIG. 7 shows a part of a configuration example of the driving support control apparatus according to the present invention, and the compensation current command value Irefa output from the subtracting unit 151 is, for example, the adding unit 32A shown in FIG. The subsequent configuration is the same as the configuration shown in FIG. The current command value calculation unit 31 also has the same configuration as the current command value calculation unit 31 shown in FIG. The description of the same configuration as in FIG. 2 is omitted.

The SAT estimation unit 110 estimates SAT T _sat from the steering torque Ts, the assist torque Tm, the motor angular velocity ωm, and the motor angular acceleration αm, and outputs it as a SAT estimated value T _se . The vehicle zero point characteristic compensation unit 120 receives the current command value Iref1, performs first-order approximation compensation, and outputs a compensation current command value Irefz. Steering information characteristic compensation unit 130 outputs a compensation signal Cs1 for time constant compensation using the SAT estimated value T _se. The vehicle attenuation characteristic compensator 140 outputs a compensation signal Cs2 for compensating for the attenuation factor using the steering angle θg. The compensation current command value Irefz is compensated by the compensation signals Cs1 and Cs2 in the adder 150 and the subtractor 151, and is output as the compensation signal Irefa.

  Each part will be described in detail.

The SAT estimation unit 110 estimates SAT T _sat by a process similar to the process disclosed in Japanese Patent No. 4192442, for example. An outline of the process will be described.

  The state of the torque generated from the road surface to the steering is as shown in FIG. 8, and the steering torque Ts is generated when the driver steers the steering wheel, and the motor generates the assist torque Tm according to the steering torque Ts. Is generated. As a result, the wheels are steered and SAT is generated as a reaction force. At that time, a torque that becomes a steering steering resistance is generated by the inertia J of the motor and the friction (static friction) Fr. From the balance of these forces, the following equation of motion is obtained.

Here, when the above equation 16 is Laplace transformed with an initial value of zero and solved for T _sat , the following equation 17 is obtained.

As can be seen from Equation 17, the SAT T _sat can be estimated from the motor angular velocity ωm, the motor angular acceleration αm, the assist torque Tm, and the steering torque Ts by previously obtaining the motor inertia J and the static friction Fr as constants. it can. The motor angular velocity ωm and the motor angular acceleration αm can be calculated from a rotation angle detected by a rotation angle sensor detected by connecting a rotation angle sensor (not shown) such as a resolver to the motor 20.

If the estimated SAT is fed back as it is, the steering becomes too heavy and the steering feeling may not be improved. Therefore, the SAT estimated value _Tse is signal-processed using a filter having frequency characteristics, and the steering is performed. Only information necessary and sufficient to improve the sense may be output. Moreover, you may estimate SAT by methods other than this method.

  The vehicle attenuation characteristic compensation unit 140 calculates a compensation signal Cs2 for performing attenuation rate compensation, that is, compensation with a yaw rate attenuation rate of about 1.

The adjustment of the yaw rate attenuation rate of the vehicle having the understeer characteristic can be performed by state feedback control in which the yaw rate γ (s) is detected and returned to the actual steering angle θt (s) as shown in FIG. . In FIG. 9A, K _STG is the steering system rigidity excluding the torsion bar, and C _γ (s) is the characteristic of the state feedback control. In order to realize this control by the function of EPS, a feedback characteristic C ₂ (s) that exchanges the configuration shown in FIG. 9A equivalently to the configuration by the control of EPS shown in FIG. 9B is used. The configuration of FIG. 9B is the same configuration as a part of the simulation model shown in FIG. 3, where STG (s) = 1 / K _STG .

The actual steering angle yaw rate transfer characteristic G _θ (s) before the state feedback control is applied is expressed by the following _equation (18).

Here, ζ _n is a yaw rate attenuation rate. T _yr is a time constant and is calculated by the following equation (19).

The state feedback control characteristic C _γ (s) that gives the yaw rate attenuation rate is given by the following equation (20).

Here, Kd is a feedback gain.

  From the formulas 18 to 20, the characteristic in the configuration shown in FIG. 9A is the following formula 21. As can be seen from the formula 21, an attenuation rate corresponding to the feedback gain Kd is added. By defining the feedback gain Kd such that is an approximate expression as shown in the following equation 22, the yaw rate attenuation rate can be made substantially 1.

The feedback characteristic C ₂ (s) that gives a characteristic equivalent to the structure shown in FIG. 9A is equal to the following Expression 23 and Expression 24 obtained from each structure shown in FIGS. 9A and 9B. From the following formula 25 derived from the conditions, the following formula 26 is obtained.

Therefore, the yaw rate attenuation factor can be set to approximately 1 by using the feedback gain Kd that satisfies the approximate expression of Equation 22 as the feedback gain Kd in Equation 26. Using this feedback characteristic C ₂ (s), the vehicle damping characteristic compensation unit 140 calculates a compensation signal Cs2 from the steering angle θg.

  The vehicle zero point characteristic compensator 120 performs first order approximate compensation, that is, compensation so that Assumption 1 and Assumption 2 hold, but the assumption 2 “the actual steering angle lateral acceleration transmission characteristic can be approximated to the primary phase characteristic” is assumed. Is assumed to be a reasonable assumption at a steering frequency of 0.5 Hz or less, which corresponds to a normal steering operation, and therefore the vehicle zero point characteristic compensation unit 120 performs compensation for which Assumption 1 is established. Since the natural frequency of the zero point of the actual steering angle lateral acceleration transmission characteristic does not depend on the vehicle speed and is in the vicinity of 2 Hz, which is larger than the pole, approximating to the primary phase characteristic is that of the pole that is secondary at 0.5 Hz or less. This is because it works in the direction of reducing the amount of phase delay, and is estimated to be a reasonable approximation. For assumption 1, the actual steering angle yaw rate transmission characteristic approximates to the first-order lag characteristic because the yaw rate transmission characteristic (that is, the vehicle characteristic) is a yaw rate characteristic with respect to the steering angle that changes in conjunction with the actual steering angle. ) Is equivalent to approximating the first-order lag characteristic, and is established by approximating the yaw rate transfer characteristic to the first-order lag characteristic.

The approximation of the yaw rate transfer characteristic to the first-order lag characteristic is performed by canceling the natural frequency of the zero point to zero. This can be done by using a feedforward controller that has a pole that cancels the zero point of the yaw rate transfer characteristic and has a zero point that has the same time constant as the pole of the yaw rate transfer characteristic. In the configuration of the EPS, the closed loop characteristics including the torsion bar 100 and the characteristic unit 101 in the simulation model shown in FIG. 3 play the role of a feedforward controller. Therefore, the steering angle θg between the steering torque _{T stg} is assumed to be proportional below 0.5 Hz, when the proportionality coefficient _{K sat,} the following equation 28 so as to satisfy the following equation 27 Feedforward characteristics _C 1 of (s) By obtaining the time constants T ₃ and T ₄ , pole-zero cancellation can be performed.

Here, K _C is a steady gain, _Kat is a power assist gain, and STG (s) = 1 / K _{STG in} FIG. Note that the above assumption is equivalent to assuming that the actual rudder angle and SAT are proportional to 0.5 Hz or less, and thus is assumed to be a reasonable assumption.

  When the yaw rate transfer characteristic is obtained from the equations (22) and (28), it can be understood that the first delay characteristic is obtained as shown in the following equation (29), and the object is achieved.

The vehicle zero point characteristic compensation unit 120 compensates the current command value Iref1 using the feedforward characteristic C ₁ (s).

The steering information characteristic compensation unit 130 calculates a compensation signal Cs1 for performing time constant compensation, that is, compensation for setting the time constant τ _sat shown in _Expression 14 so as to match the driver characteristics. This is realized by filtering the SAT estimated value.

The SAT estimation can be performed using an external observer, and the configuration in the case where the SAT estimation is performed using the external observer is as shown in FIG. In FIG. 10A, C (s) is a characteristic of a control system including a torsion bar, F (s) is a filter characteristic, Q (s) is a characteristic of a disturbance observer compensator, and STGn (s) is a nominal dynamic characteristic. It is. When the SAT estimated value T _se in FIG. 10A matches the actual SAT T _{sat, the} configuration shown in FIG. 10A can be equivalently exchanged with the configuration shown in FIG. 10B. Then, the condition of the filter characteristic F (s) for the time constant τ _sat to be a desired time constant τ _r that _{matches the} driver characteristic is the following Expression 30. When Expression 13 is substituted into Expression 30, the filter characteristic F (s) is expressed by Equation 31 below.

Further, since the estimated disturbance values only need to match within a range of about 10 Hz or less, the characteristic Q (s) of the disturbance observer compensator is set to approximately 1 at 10 Hz or less. Therefore, the steering information characteristic compensation unit 130 calculates the compensation signal Cs1 from the SAT estimated value _Tse using the filter characteristic F (s).

  In the above configuration, an operation example of the first embodiment will be described with reference to the flowchart of FIG.

  When the operation starts, the vehicle speed V, the steering torque Ts, the motor angular velocity ωm, the motor angular acceleration αm, the assist torque Tm, and the steering angle θg are input (step S10). Among these, the vehicle speed V is supplied to the current command value calculation unit 31, the steering torque Ts is supplied to the current command value calculation unit 31 and the SAT estimation unit 110, the motor angular velocity ωm, the motor angular acceleration αm, and the assist torque Tm are supplied to the SAT estimation unit 110. The steering angle θg is input to the vehicle damping characteristic compensator 140, respectively. The motor angular acceleration αm is calculated by differentiating the motor angular velocity ωm.

  The current command value calculation unit 31 calculates the current command value Iref1 from the vehicle speed V and the steering torque Ts as in the case of the configuration shown in FIG. 2 (step S20), and outputs it to the vehicle zero point characteristic compensation unit 120.

The SAT estimation unit 110 calculates a SAT estimated value T _se that is an estimated value of SAT T _sat from Equation 17 using the steering torque Ts, the motor angular velocity ωm, the motor angular acceleration αm, and the assist torque Tm (step S30). The estimated value T _se is input to the steering information characteristic compensation unit 130. Note that the operations of the current command value calculation unit 31 and the SAT estimation unit 110 may be executed in parallel, even if the order is changed.

The vehicle zero point characteristic compensator 120 to which the current command value Iref1 is input converts the current command value Iref1 using Equation 26 and outputs it as a compensated current command value Irefz (step S40). In Formula 26, an appropriate value is set in advance for the power assist gain _Kat , and values adjusted in advance so as to satisfy Formula 25 are set in the time constants T ₃ and T ₄ . The compensation current command value Irefz is input to the adding unit 150.

Steering information characteristic compensation unit 130 input the SAT estimated value _{T se} converts the SAT estimated value _{T se} using equation 29, and outputs a compensation signal Cs1 (step S50). A value determined in advance is set in the time constant τ _sat in the equation 29, and a desired value is set in advance in the time constant τ _r . The compensation signal Cs1 is input to the adder 150. Note that the operations of the vehicle zero point characteristic compensation unit 120 and the steering information characteristic compensation unit 130 may be executed in parallel, even if the order is changed.

  The compensation current command value Irefz input to the adding unit 150 is compensated by adding the compensation signal Cs1 (step S60), and is output as the compensation current command value Ireft. The compensation current command value Ireft is added to the subtraction unit 151 and input.

The vehicle attenuation characteristic compensator 140 that has received the steering angle θg converts the steering angle θg using Equation 24 and outputs a compensation signal Cs2 (step S70). Values obtained in advance are set for G _θ (0), K _STG , time constant τ _n , and yaw rate attenuation rate ζ _n in Equation 24 so that the approximate expression of Equation 22 is established for feedback gain Kd. A value adjusted in advance is set. The compensation signal Cs2 is subtracted and input to the subtraction unit 151.

  The compensation current command value Ireft input to the subtraction unit 151 is compensated by subtracting the compensation signal Cs2 (step S80), and is output as the compensation current command value Irefa.

  Since the steering angle and the motor angle have a proportional relationship, the vehicle damping characteristic compensation unit 140 may use a motor angle instead of the steering angle. Further, the steering information characteristic compensation unit 130 may use steering torque instead of the SAT estimated value. In this case, it is necessary to perform conversion in consideration of steering dynamic characteristics.

  Here, the effect of this embodiment will be described.

  In order to confirm the effects of the three compensations (attenuation rate compensation, first-order approximation compensation, and time constant compensation) performed in this embodiment, a vehicle having an understeer characteristic equipped with the exercise support control device of this embodiment is used. Then, the lane change operation was performed only by the difference of the presence or absence of compensation without changing the static power assist characteristics, and the convergence with respect to the target trajectory was compared. Regarding the convergence at the time of lane change, such a comparison was made because it is known that the steering operation load increases as the convergence is poor and overshoot occurs. The specifications of the vehicle used are as shown in Table 2 below, and the lane change running is performed at a vehicle speed of 80 km / hour in which the highest yaw rate of about 15 ° / second appears in the off-center region, and the convergence characteristics for the target trajectory are substituted. The overshoot of the yaw rate was evaluated by giving the course constraint condition shown in FIG.

In driving, the driver gave informed consent for the purpose of evaluation in advance.

  The evaluation results are shown in FIG. FIG. 13A shows the result when compensation is not performed, and FIG. 13B shows the result when compensation is performed. The vertical axis is yaw rate and steering torque, and the horizontal axis is time. FIG. 13 shows that overshoot is observed immediately before the yaw rate converges when no compensation is performed, but no overshoot occurs when compensation is performed. This is presumed to be because the phase characteristic of the steering torque with respect to the yaw rate has an influence. Without compensation, the phase difference between the yaw rate and the steering torque changes depending on the steering state, so it is difficult to recognize the yaw rate from the steering torque information, and steering was performed more than necessary, leading to overshoot. Presumed to be. On the other hand, when compensation was performed, the phase relationship between the steering torque and yaw rate during steering was almost constant, and it was assumed that the driver could control the yaw rate with the steering torque information, so that no overshoot occurred. Is done. As described above, it was confirmed that the yaw rate overshoot was suppressed and the steering operation load was reduced by the three compensations according to the present embodiment.

  Next, an embodiment (second embodiment) for a vehicle having a neutral steer characteristic will be described.

  FIG. 14 shows a configuration example of the second embodiment. FIG. 14 shows a part of a configuration example of the driving support control device according to the present invention, as in the case of FIG. As described above, the vehicle having the neutral steer characteristic has a yaw rate attenuation rate of approximately 1, and it is not necessary to perform attenuation rate compensation. Therefore, the second embodiment is compared with the first embodiment shown in FIG. The vehicle damping characteristic compensation unit 140 is not provided. Therefore, the steering angle θg is not input, and the compensation current command value Ireft output from the adder 150 instead of the compensation current command value Irefa is input to the adder 32A shown in FIG.

  FIG. 15 shows an operation example of the second embodiment. Compared to the operation example of the first embodiment shown in FIG. 11, the operation in the vehicle attenuation characteristic compensation unit 140 (step S70) and the attenuation rate compensation (step S80) by the compensation signal Cs2 which is the operation result are unnecessary. It has become. Other operations are the same as the operation example of the first embodiment.

  In the above-described embodiments (the first embodiment and the second embodiment), all the compensation is performed using EPS, but other systems and mechanisms mounted on the vehicle perform some compensation. It is also possible for the EPS to perform the remaining compensation. For example, attenuation rate compensation and first-order approximation compensation can be executed by 4WS (four-wheel steering), variable gear ratio mechanism, SBW (Steer By Wire), etc., and time constant compensation can be executed by SBW or the like. 4WS is a system that steers by changing the direction of not only the front two wheels but also the rear two wheels when changing the direction of the vehicle, and it is possible to suppress changes in phase due to yaw rate response, etc. And first order approximation compensation can be performed. The variable gear ratio mechanism is a mechanism that appropriately controls the steering gear ratio according to the vehicle speed. By using it in combination with EPS, it is possible to automatically adjust the yaw rate transmission characteristic, which is a vehicle characteristic, and the attenuation rate. Compensation and first order approximation compensation can be performed. The SBW is a system that transmits an operation of the steering wheel by an electrical signal, and can perform steering system control with a high degree of freedom. Therefore, attenuation rate compensation, first-order approximation compensation, and time constant compensation can be executed. However, since SBW is generally used as a substitute for EPS, when it is used together with EPS, only the compensation shared by SBW is executed. For example, as shown in FIG. 16, in addition to the driving support control device 70 according to the present invention, a 4WS mechanism is incorporated in the front wheel steering gear box 50 and the rear wheel steering gear box 51, and the variable gear ratio is In a vehicle in which the mechanism 60 is installed adjacent to the motor 20, the variable gear ratio mechanism 60 or 4WS executes the attenuation rate compensation and the first-order approximation compensation, and the driving support control device 70 executes only the time constant compensation. It is possible. A configuration example (third embodiment) of the embodiment of the present invention in this case is as shown in FIG. 17, and compared with the first embodiment shown in FIG. 7, the vehicle zero point characteristic compensating unit 120 and the vehicle damping characteristic compensating unit. The configuration without 140 is provided. Then, the current command value Iref1 output from the current command value calculation unit 31 is compensated by the addition unit 152 by adding the correction signal Cs1 output from the steering information characteristic compensation unit 130, and the compensation current command value Ireft The compensation current command value Ireft 'is input to the adder 32A shown in FIG.

1 Handle 2 Column shaft (steering shaft, handle shaft)
10 Torque sensor 12 Vehicle speed sensor 20 Motor 30 Control unit (ECU)
31 Current command value calculation unit 110 SAT estimation unit 120 Vehicle zero point characteristic compensation unit 130 Steering information characteristic compensation unit 140 Vehicle damping characteristic compensation unit

Claims (9)

In the driving assistance control device using the electric power steering mechanism that drives the motor based on the current command value to assist the steering system,
A vehicle zero point characteristic compensator for compensating the current command value so that the vehicle characteristic from the steering angle to the yaw rate approximates the first order lag characteristic;
A steering information characteristic compensation unit for compensating the current command value so that a time constant of the steering information characteristic from the vehicle behavior information to the steering information becomes a desired value;
Including at least one of a vehicle attenuation characteristic compensator that compensates the current command value using angle information so that an attenuation rate of the vehicle characteristic is approximately 1.
By compensating the current command value for at least one of the vehicle zero point characteristic compensation unit, the steering information characteristic compensation unit, and the vehicle damping characteristic compensation unit for a vehicle having a small rear wheel cornering compliance Cr in normal steering operation. A driving support control apparatus using an electric power steering mechanism that reduces a burden of steering driving of the vehicle. In the driving assistance control device using the electric power steering mechanism that drives the motor based on the current command value to assist the steering system,
A vehicle zero point characteristic compensator for compensating the current command value so that the vehicle characteristic from the steering angle to the yaw rate approximates the first order lag characteristic;
At least one of a steering information characteristic compensation unit that compensates the current command value so that a time constant of a steering information characteristic from vehicle behavior information to steering information becomes a desired value;
By compensating the current command value by at least one of the vehicle zero point characteristic compensation unit and the steering information characteristic compensation unit for a vehicle having a small rear wheel cornering compliance Cr in a normal steering operation and a neutral steering characteristic, A driving support control apparatus using an electric power steering mechanism, which reduces a burden of steering driving of the vehicle. The vehicle zero point characteristic compensator is
By performing pole-zero cancellation so that the characteristic by the torsion bar and the vehicle zero-point compensation unit has a pole that cancels the zero of the vehicle characteristic and has a zero equivalent to the pole of the vehicle characteristic,
The driving assistance control device using the electric power steering mechanism according to claim 1 or 2, wherein the vehicle characteristic is approximated to a first-order lag characteristic. The vehicle behavior information is a yaw rate,
The driving support control device using the electric power steering mechanism according to claim 1 or 2, wherein the steering information is a steering torque.   The driving support control apparatus using an electric power steering mechanism according to claim 4, wherein the steering information characteristic compensation unit compensates the current command value using a self-aligning torque.   The driving support control apparatus using an electric power steering mechanism according to claim 1, wherein the vehicle damping characteristic compensation unit uses a steering angle as the angle information. The rear wheel cornering compliance Cr is
With respect to the wheel base L, the front axle center-of-gravity point distance Lf, the rear axle center-of-gravity point distance Lr, the weight M, the yaw moment of inertia Ym, and the vehicle speed V,
The driving assistance control apparatus using the electric power steering mechanism according to any one of claims 1 to 6, wherein the rear wheel cornering compliance Cr is small when the condition is satisfied.   The driving support control device using the electric power steering mechanism according to any one of claims 1 to 7, wherein the normal steering operation is performed when a steering frequency is approximately 0.5 Hz or less. A vehicle equipped with a driving support control device using the electric power steering mechanism according to any one of claims 1 to 8.