JP2010162958A - Vehicle control device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a vehicle control device which determines the degree of familiarity of a driver to operate a vehicle, taking a driving condition, a driving course of the vehicle, or the like into consideration. <P>SOLUTION: The vehicle control device calculates the degree of familiarity of the driver to operate the vehicle based on a vehicle condition when the vehicle turns and steering angular velocity of the driver. The vehicle control device also calculates the degree of familiarity of the driver to operate the vehicle based on a frequency characteristics of a familiarity evaluation variable Z. Provided that Gmax is a maximum value of the lateral G in turning when the vehicle makes a turn, V is the speed of the vehicle, Δθ is the steering angular velocity of the driver, Kh is the stability factor of the vehicle, L is the wheel base of the vehicle, and N is the gear ratio of the steering angle with respect to the turning angle of the vehicle, the familiarity evaluation variable Z can be obtained from a given formula using each parameter. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a vehicle control device that determines a steering familiarity based on a vehicle state.

  Various technical ideas have been proposed for techniques for assisting the steering of a driver in a vehicle including a steering device employing a steer-by-wire system. In a steer-by-wire vehicle, a steering shaft connected to a steering wheel operated by a driver and a steered wheel that determines a traveling direction of the vehicle are mechanically separated.

  With the steer-by-wire system, the degree of freedom of steering arrangement is increased, and the amount of steering can be automatically changed according to the vehicle's movement state and driving environment, etc., and more comfortable and safe driving can be realized. Be expected.

  The steer-by-wire method can freely design the ratio between the steering angle of the steering wheel and the turning angle of the wheel (also referred to as “gear ratio”). Therefore, it is possible to design to steer large with respect to a small steering amount, or to steer small with respect to a large steering amount. Thus, in recent years, the degree of freedom of the steering characteristics between the steering amount and the steering amount tends to increase.

JP 2006-232172 A JP 2008-87533 A

  When assisting the driver in steering the vehicle using the steer-by-wire system, when determining how familiar the driver is with the vehicle, the driver's steering angular velocity and vehicle state Was not judged on the basis of.

  For this reason, it has been difficult for the vehicle control device to more accurately determine the degree of operation familiarity of the vehicle in consideration of the driving state by the driver, the driving course of the vehicle, and the like.

  The present invention has been made in view of the above-described problems, and an object of the present invention is to provide a vehicle control device that determines the degree of operation familiarity of a vehicle in consideration of a traveling state by a driver, a traveling course of the vehicle, and the like.

  The vehicle control device according to the present invention calculates the driver's familiarity with the operation of the vehicle based on the vehicle state when the vehicle turns and the driver's steering speed. In addition, the vehicle control device according to the present invention may preferably calculate the driver's familiarity with the operation of the vehicle based on the frequency characteristics of the familiarity evaluation variable Z. However, the habituation evaluation variable Z is assumed to be a time change equivalent value of the lateral G calculated based on the operation of the driver with respect to the value related to the actually measured lateral G. In the vehicle control device according to the present invention, more preferably, the actually measured value related to the lateral G may be the maximum value of the lateral G when the vehicle turns.

  In addition, the vehicle control device according to the present invention may preferably calculate the driver's familiarity with the operation of the vehicle based on the frequency characteristics of the familiarity evaluation variable Z. However, when the vehicle turns, the maximum value of lateral G in the turn is Gmax, the vehicle speed is V, the driver's steering angular velocity is Δθ, the vehicle stability factor is Kh, and the vehicle wheelbase If L is L and the gear ratio that is the steering angle with respect to the turning angle of the vehicle is N, the familiarity evaluation variable Z is given by the following equation (1).

  The vehicle control device according to the present invention more preferably determines whether or not the vehicle is turning based on whether or not the lateral G applied to the vehicle is greater than a predetermined lateral G threshold, and the vehicle does not turn. In this case, the vehicle control device calculates the driver's familiarity with the operation of the vehicle based on the frequency characteristic of the familiarity evaluation variable Z. However, when the vehicle does not turn, Gmax is a predetermined lateral G threshold, the vehicle speed is V, the driver's steering angular velocity is Δθ, the vehicle stability factor is Kh, and the vehicle wheel If the base is L and the gear ratio that is the steering angle with respect to the turning angle of the vehicle is N, the familiarity evaluation variable Z is given by the following equation (2).

  According to the present invention, it is possible to provide a vehicle control device that determines the degree of operation familiarity of a vehicle in consideration of a driving state by a driver, a driving course of the vehicle and the like.

It is a flowchart which illustrates notionally the operation process of the vehicle control apparatus concerning embodiment. It is a typical conceptual diagram explaining the relationship between the time change of a driver | operator's steering angle, and the horizontal G detected by G sensor of a vehicle. It is a figure which shows the basic composition of a vehicle. It is a figure which shows the change of the steering wheel operation amount by a driver | operator. It is a figure which shows the change of the difference of the steering wheel operation amount by a driver | operator, and an ideal value. It is a block diagram which shows the structure of the part which concerns on this embodiment among steering control units. It is a figure which shows the relationship between a cutoff frequency and a vehicle speed. It is a figure which shows the relationship between a steering angular velocity and a phase correction amount. It is a flowchart which shows the determination process of a familiarity degree. It is a flowchart which shows the determination process of a familiarity degree.

  The vehicle control apparatus exemplified in the present embodiment reflects the driver's travel mode such as the normal mode or the sport travel mode, and determines the degree of familiarity with the steer characteristic. By determining the degree of familiarity with respect to the steering characteristics reflecting the driving mode of the driver, it becomes possible to determine the degree of familiarity with steering more accurately.

  For example, if the same driver travels on the same course at a fast speed and a slow speed, the driver can travel at a slow speed if the degree of steering familiarity is judged based only on the frequency characteristics of the operation amount of the driver. It tends to be judged that the degree of familiarity is higher.

  Therefore, the vehicle control apparatus described below determines the degree of familiarity in consideration of the driving state of the vehicle such as the turning lateral G of the vehicle and the yaw rate in addition to the identification of the driver's operation input. Further, the traveling state of the vehicle may be determined based on vehicle traveling position information or the like.

  For example, when the vehicle turns a corner, the vehicle control device stores the detected value of the lateral G during the turning of the vehicle. When the turning of the vehicle is completed, the maximum value Gmax of the lateral G received by the vehicle in the turning is determined. Further, a familiarity evaluation variable Z is calculated from the speed of the vehicle during the turn, the steering angular speed, and the like, and the maximum value Gmax of the lateral G. Note that the lateral G is lateral acceleration applied to the vehicle.

  The vehicle control device determines the vehicle steering familiarity of the driver based on the frequency characteristic of the familiarity evaluation variable Z described above. Here, the frequency characteristic of the habituation evaluation variable Z includes, for example, a characteristic obtained by extracting a high frequency component of the habituation evaluation variable Z. When the driver is unfamiliar, a high frequency component tends to be superimposed on the steering angular velocity, the steering amount, etc., but the familiarity evaluation variable Z can be processed and evaluated in the same manner as the steering angular velocity, the steering amount, etc. Therefore, the operation process of the vehicle control device will be described in detail below. FIG. 1 is a flowchart conceptually illustrating operation processing of the vehicle control device according to the embodiment.

(Step S110)
The vehicle control device detects the lateral G of the vehicle by a G sensor attached to the vehicle.

(Step S120)
The vehicle control device determines whether or not the vehicle is turning based on whether or not the detected lateral G of the vehicle is larger than a predetermined lateral G threshold (hereinafter also referred to as Kgmax as appropriate). If the detected lateral G of the vehicle is larger than a predetermined lateral G threshold (hereinafter also referred to as Kgmax as appropriate), in other words, if the vehicle is turning, the process proceeds to step S130. If the detected lateral G of the vehicle is not greater than a predetermined lateral G threshold (hereinafter also referred to as Kgmax as appropriate), in other words, if the vehicle is not turning, the process proceeds to step S190.

(Step S130)
The vehicle control device stores a lateral G of the vehicle during turning, that is, a detection value of the G sensor.

(Step S140)
The vehicle control device determines whether or not the vehicle is turning based on whether or not the detected lateral G of the vehicle is larger than a predetermined lateral G threshold (hereinafter also referred to as Kgmax as appropriate). If the detected lateral G of the vehicle is larger than a predetermined lateral G threshold (hereinafter also referred to as Kgmax as appropriate), in other words, if the vehicle is turning, the process stands by in step S140. If the detected lateral G of the vehicle is not greater than a predetermined lateral G threshold (hereinafter also referred to as Kgmax as appropriate), in other words, if the vehicle is not turning, the process proceeds to step S150.

(Step S150)
The vehicle control device calculates the maximum value Gmax of the side G of the corner that has turned based on the stored value of the side G of the vehicle stored in step S130. That is, the vehicle control device obtains the maximum value of the G sensor of the corner that has turned.

  Since the vehicle control device only needs to detect the maximum value Gmax of the lateral G in the curve in steps S130 to S150, it is not necessary to store all the detected values of the G sensor during turning. The vehicle control device may store only the maximum value of the already-turned curve of the curve being turned, and may store the replacement value when the detected value exceeds the stored value. As a result, the vehicle control device stores only the maximum value Gmax of the lateral G in the curve at the end of the turn.

(Step S160)
The vehicle control device obtains Δg corresponding to the time change of the lateral G by arithmetic processing. Here, Δg is calculated by the following equation (3). Note that Δg may be an amount equivalent to the time change of G (lateral G or the like) of the vehicle calculated or simulated from the steering angular velocity of the driver, and the method of calculating Δg is not limited to the following formula (3). Absent.

  Here, the vehicle speed is V, the driver's steering angular velocity is Δθ, the vehicle stability factor is Kh, the vehicle wheelbase is L, and the gear ratio that is the steering angle with respect to the vehicle turning angle is N. And Since the vehicle speed V and the driver's steering angular velocity Δθ change with the elapsed time as the vehicle travels, it is assumed that arithmetic processing is performed at any time, for example, every desired sampling time. Note that if the steering angular velocity of the driver is divided by Δθ by the gear ratio N, the tire turning angular velocity Δδ is obtained. Therefore, the steering angular velocity may be replaced with Δθ and the tire turning angular velocity Δδ may be used.

  The vehicle stability factor Kh is a coefficient obtained by indexing the performance of the vehicle tire and the suspension, and is a stability coefficient peculiar to the vehicle determined from the force relationship generated in the front and rear tires. However, since it is well known to those skilled in the art, a detailed description is avoided here.

(Step S170)
The vehicle control device calculates the familiarity evaluation variable (Z). The familiarity evaluation variable (Z) is obtained by the following formula (4) or the following formula (5). If it is determined in step S120 that the vehicle is turning, the following equation (4) is used. If it is not determined in step S120 that the vehicle is turning, the following equation (5) is used. Shall. As shown in Equation (4) and Equation (5), the familiarity evaluation variable (Z) shown in this embodiment is a change in the lateral G calculated based on the driver's operation with respect to a value related to the actually measured lateral G. It may be a substantial part, and is not limited to the relational expression exemplified. A typical example of the value related to the actually measured lateral G is Gmax or the lateral G threshold value, but the actually measured value related to the lateral G may be, for example, an average value of the lateral G generated in the vehicle within a certain period. It is not limited to. A typical example corresponding to the change in the lateral G calculated based on the driver's operation is Δg calculated by Expression (3).

  Since the vehicle speed V and the driver's steering angular velocity Δθ change with time as the vehicle travels, it is assumed that the accustomed evaluation variable (Z) is calculated at any desired sampling time, for example. If the vehicle is not turning around the curve, the value of Gmax is fixed to a predetermined lateral G threshold value in step S190, so that it is based on the speed V during which the vehicle is traveling and the steering angular speed Δθ at that time. Thus, the familiarity evaluation variable (Z) can be calculated from the equation (5) in real time. On the other hand, if the vehicle is turning on a curve, the familiarity evaluation variable (Z) during turning of the curve cannot be calculated until the turning of the curve is finished and Gmax is determined in step S150. Therefore, the vehicle control device may store the velocity V detected while the vehicle is turning the curve and the steering angular velocity Δθ in association with each other. After the curve turn is completed and Gmax is determined in step S150, the vehicle control device reads the stored vehicle speed V and steering angular velocity Δθ during the curve turn, and uses the habituation evaluation variable (Z) during the curve turn. Can be calculated.

(Step S180)
The vehicle control apparatus evaluates a steering familiarity (to be described later) based on the frequency component of the familiarity evaluation variable (Z) itself using the familiarity evaluation variable (Z) calculated in step S170 as an input value.

(Step S190)
The vehicle control device sets Gmax as a lateral G threshold value (Kgmax).

  FIG. 2 is a schematic conceptual diagram illustrating a relationship between a change in the steering angle of the driver with time and a lateral G detected by the G sensor of the vehicle. As shown in FIG. 2, if the absolute value of the lateral G is smaller than Kgmax, the vehicle control device does not determine that the vehicle is turning. In this case, calculation processing is performed assuming that Gmax is Kgmax without calculating the value of Gmax.

  If the absolute value of the lateral G is greater than Kgmax, the Gmax detection process is performed assuming that the vehicle is turning. In this case, Gmax is the maximum value or the minimum value of the lateral G. As shown in FIG. 2, if the sign of the lateral G to be detected is reversed plus or minus, it is assumed that the turning direction is different, for example, a right curve and a left curve, and the corners are different.

  An example of determining the driver's steering familiarity based on the frequency characteristics of a predetermined input value will be described below by way of example. For example, the vehicle control device can perform arithmetic processing in the same manner as in the following arithmetic processing example only by replacing the input value with the familiarity evaluation variable (Z) for the processing in step S180 shown in FIG.

  FIG. 3 is a diagram illustrating a basic configuration of the vehicle 10. FIG. 3 is a schematic diagram of the front wheel portion of the four wheels. The vehicle 10 determines the traveling direction of the vehicle by steering the right front wheel FR and the left front wheel FL, which are steered wheels.

  The vehicle 10 includes a steering wheel 12 steered by a driver, a steering shaft 14 coupled to the steering wheel, a gear box 44 provided at the lower end of the steering shaft 14, and an output shaft connected to the gear box 44. And a steering reaction force motor 46.

  The rotational force generated by the steering reaction force motor 46 is transmitted to the steering shaft 14 via the gear box 44 and gives a steering reaction force to the steering wheel 12. This steering reaction force is applied in order to sensuously transmit the frictional force between the road surface and the steered wheels, the self-aligning torque, and the like to the driver.

  A steering torque sensor 16 that detects torque generated in the steering shaft 14 and a steering angle sensor 18 that detects the steering angle of the steering wheel 12 are installed on the steering shaft 14 as operation amount sensors. Outputs of operation amount sensors including the steering torque sensor 16 and the steering angle sensor 18 are transmitted to the steering control unit 100.

  The right front wheel FR and the left front wheel FL are steered by the steering mechanism 20. The steering mechanism 20 is disposed in a state of being mechanically separated from the steering shaft 14 and is set in advance with respect to a transmission ratio (corresponding to a gear ratio) between the steering angle of the steering wheel 12 and the steering angle of the wheel. The wheels are steered according to the rudder characteristics.

  The steering mechanism 20 includes a rack bar 22 that extends in the left-right direction (vehicle width direction) of the vehicle and slides in the axial direction. The rack bar 22 is combined with a steering motor 24 and a ball screw mechanism (not shown). The rotation of the steering motor 24 is converted into a linear motion of the rack bar 22 in the left-right direction by a ball screw mechanism.

  One ends of tie rods 26R and 26L are connected to both ends of the rack bar 22, respectively. The other ends of the tie rods 26R and 26L are connected to knuckle arms 30R and 30L that support the right front wheel FR and the left front wheel FL. The knuckle arms 30R and 30L rotate with the king pins 32R and 32L as fulcrums, respectively. When the rack bar 22 moves linearly, the right front wheel FR and the left front wheel FL are steered.

  A vehicle speed sensor 36 that detects the rotational speed of the wheel and outputs the vehicle speed is attached in the vicinity of the left front wheel FL. In addition, a turning angle sensor 34 that detects the amount of displacement in the left-right direction with respect to the neutral position of the rack bar 22 and outputs the turning angle of the left and right wheels based on the amount of displacement is also installed. The vehicle speed and the turning angle are transmitted to the steering control unit 100.

  The steering control unit 100 receives the output values of the steering torque sensor 16, the steering angle sensor 18, the turning angle sensor 34, and the vehicle speed sensor 36. The steering control unit 100 calculates a steering reaction force command value and a turning angle command value based on these input values, and outputs control signals corresponding to these to the steering reaction force motor 46 and the steering motor 24.

  In the steer-by-wire vehicle as shown in FIG. 3, the transmission ratio between the steering angle of the steering wheel and the turning angle of the wheel can be designed freely. For example, it is also considered to design the wheel so that the steering angle of the wheel necessary to reach the wheel from the neutral position to the maximum turning angle is about half a circle.

  This eliminates the need to swap the left and right arms in order to rotate the steering wheel, for example, during a right or left turn of the vehicle, thereby reducing the driver's effort in handling the wheel. Such a correspondence between the steering angle of the steering wheel and the turning angle of the wheel is also referred to as a small steering angle steer.

  While a vehicle with a small steering angle steer has the above-mentioned advantages, the steering wheel required for turning is small, so steering is more than necessary when the driver is unfamiliar with such characteristics. There is a possibility that. If steering is performed more than necessary, a correction operation for returning the steering angle is also required, and as a result of the correction operation being performed in small increments, smooth operation may be difficult.

  Therefore, in this embodiment, it is determined whether the driver is accustomed to the steering characteristics of the vehicle, and depending on the determination result, the steering characteristics are changed to further improve driving comfort and safety. .

  FIG. 4 shows changes in the steering wheel operation amount by the driver. In FIG. 4, the solid line indicates the change in the operation amount by the driver unfamiliar with the steering characteristics, and the broken line indicates the ideal change in the operation amount by the driver who is accustomed to the steering characteristics. The horizontal axis represents time, and the vertical axis represents the manipulated variable.

  The operation amount here is, for example, an input amount such as a steering angle, a steering angular velocity, and torque of the steering wheel. The ideal waveform shown by a broken line is a smooth waveform with few high-frequency components, whereas the waveform of an unfamiliar driving operation shown by a solid line appears to be a small waveform with many high-frequency components. Therefore, it can be assumed that an ideal operation waveform can be obtained by removing high frequency components from the actual operation amount. It should be noted that the familiarity evaluation variable (Z) may be input as the operation amount, as described above, instead of the input amount such as the steering angle, the steering angular velocity, and the torque of the steering wheel.

  FIG. 5 shows a change in the difference between the steering wheel operation amount by the driver and the ideal value. That is, the change in the difference between the operation amount indicated by the solid line and the ideal value indicated by the broken line in FIG. 4 is represented in the graph of FIG. The horizontal axis indicates time t, and the vertical axis indicates the difference δ. In this embodiment, when the difference δ exceeds a certain number a to −a, it is determined that the driver is unfamiliar with the steering characteristics at that time.

  FIG. 6 is a block diagram illustrating a configuration of a portion related to the present embodiment in the steering control unit 100 illustrated in FIG. 3. Each block shown here can be realized in hardware by an element such as a computer CPU or memory, an electronic circuit, or an electric circuit, and in software by a computer program or the like. It is drawn as functional blocks realized by cooperation. Therefore, those skilled in the art will understand that these functional blocks can be realized in various forms by a combination of hardware and software.

  The steered control unit 104 executes drive control of the steered motor 24 according to the steering angle of the steering wheel 12. The steering reaction force control unit 106 performs drive control of the steering reaction force motor 46 according to the steering angle of the steering wheel 12. The characteristic control unit 102 determines the degree of familiarity with the operation by the driver based on information such as the steering angle of the steering wheel 12 and the vehicle speed, and sets an appropriate turning characteristic in the target yaw rate setting unit 120.

First, each block of the steering control unit 104 will be described. The target yaw rate setting unit 120 receives the steering angle Ma from the steering angle sensor 18 and the vehicle speed V from the vehicle speed sensor 36, and generates a target yaw rate to be generated in the vehicle body in order to stabilize the turning of the vehicle according to a preset logic. to set the Y _t.

The target yaw rate Y _t may be obtained with reference to a three-dimensional map in which the target yaw rate is determined with respect to the steering angle Ma as a steering characteristic prepared in advance, or the steering angle Ma is substituted into a predetermined calculation formula. You may ask for it.

  The inverse model analysis unit 122 holds a vehicle motion model. This motion model is, for example, an equation of motion in a horizontal plane in which the turning angle and vehicle speed of the left and right wheels are input, the yaw rate is output, and the vehicle is regarded as a linear two-wheel model under the assumption that other conditions are constant. Can be represented.

Inverse model analysis unit 122 substitutes the vehicle speed V and the target yaw rate Y _t with respect to the inverse model of this vehicle model, it calculates the target turning angle theta _t for realizing the target yaw rate Y _t. Since the method for obtaining the yaw rate using such a vehicle model is well known, detailed description thereof is omitted in this specification.

Instead of using the inverse model, the target turning angle may be obtained simply by referring to a two-dimensional map in which the target turning angle θ _t corresponding to the target yaw rate Y _t is determined. In this case, a correction coefficient for correcting the target turning angle according to the vehicle speed V may be multiplied.

The turning angle calculation command unit 124 receives the target turning angle θ _t from the inverse model analysis unit 122 and also receives the actual turning angle θ _r from the turning angle sensor 34. And based on the difference of target turning angle (theta) _t and actual turning angle (theta) _r , a turning angle command value is calculated | required by a well-known PID control calculation. Further, a control signal corresponding to the turning angle command value is supplied to the motor drive circuit 126.

  The motor drive circuit 126 drives the steering motor 24 in accordance with a control signal from the turning angle calculation command unit 124. The steering motor 24 moves the rack bar 22 in the left-right direction via the ball screw mechanism, and accordingly the left front wheel FL and the right front wheel FR are steered.

  Next, each block of the steering reaction force control unit 106 will be described.

Target steering reaction force calculation unit 128 receives the steering angle Ma from the steering angle sensor 18 sets the target steering reaction force M _t accordingly. The target steering reaction force M _t may be obtained with reference to a two-dimensional map prepared in advance with the target steering reaction force determined with respect to the steering angle Ma, or the steering angle Ma is substituted into a predetermined calculation formula. You may ask for it.

The target steering reaction force M _t reproduces the force transmitted from the wheel to the driver via the steering wheel due to frictional force between the wheel and the road surface, self-aligning torque, or the like in a normal vehicle that is not steer-by-wire. Is set as follows.

The steering reaction force calculation command unit 132 receives the target steering reaction force M _t and the actual torque M _tr detected by the steering torque sensor 16. Then, based on the difference between the final steering reaction force M _t and the actual torque M _tr, a reaction force torque command value is obtained by a known PID control calculation. Further, a control signal corresponding to the reaction force torque command value is supplied to the motor drive circuit 134.

  The motor drive circuit 134 drives the steering reaction force motor 46 in accordance with the control signal from the steering reaction force calculation command unit 132, and the steering reaction force of the steering wheel is generated.

  Since basic control methods of the steering angle control and the steering reaction force control in the steer-by-wire vehicle are well known, detailed descriptions other than the characteristic portions are omitted in this specification.

  Next, each block of the characteristic control unit 102 will be described. The determination processing unit 114 obtains a difference between the detected value and the ideal value by using a predetermined filter process for the detected value of the operation amount sensor. The determination processing unit 114 determines the driver's familiarity with the currently set turning characteristics based on the small difference obtained.

The turning characteristic setting unit 116 sets the turning characteristic in the target yaw rate setting unit 120 so that the difference between the detected value and the ideal value decreases based on the determined degree of familiarity. The target yaw rate setting unit 120 determines the target yaw rate Y _t using a three-dimensional map or a calculation formula corresponding to the set turning characteristics. Thereby, the transmission ratio of the turning angle to the steering angle changes.

  The turning characteristic setting unit 116 sets the turning characteristic of a so-called small steering angle steer, in which the turning angle is relatively large with respect to the steering angle, to the target yaw rate setting unit 120 in principle. In addition, when the difference between the detected value of the steering wheel operation amount and the ideal value is larger than a predetermined allowable value and it is determined that the driver is unfamiliar with the turning characteristics, the turning angle becomes relatively small. Such a conventional steering characteristic that is not a small steering angle steer is temporarily set in the target yaw rate setting unit 120. When the engine is terminated, the temporary setting is also discarded, and the steering characteristic of the small steering angle steer is set again at the next start.

  The abnormality detection unit 112 detects an abnormality on the traveling road surface by a predetermined detection unit. The abnormality detection unit 112 in the present embodiment detects foreign objects such as obstacles and unevenness that are not on a normal road surface by image recognition processing from an image around the vehicle obtained from the external monitor 40. The image around the vehicle may be an image in front of the traveling direction, or may be an image on the side or rear of the vehicle.

  When an abnormality is detected on the traveling road surface by the abnormality detection unit 112, the determination processing unit 114 regulates the determination of the familiarity level. For example, when an abnormality is detected, the determination processing unit 114 may avoid determination of the familiarity level itself, or may change a value indicating the familiarity level or a determination reference value.

  Thus, when there is an abnormality on the road surface, there is a risk that the steering operation will increase rapidly due to the necessity of emergency avoidance. By excluding such an emergency avoidance operation from the analysis target of the familiarity level determination, it is possible to improve the accuracy of the familiarity level determination and suppress unnecessary changes in the steering characteristics due to such a situation. Steering characteristics can be maintained as constant as possible.

  As a modification, the abnormality detection unit 112 may detect an abnormality on the traveling road surface by a detection unit such as an ultrasonic wave or a radar instead of the external monitor 40.

  Next, an example of the familiarity level determination will be described in detail. In the following example, the driver's familiarity level is determined by obtaining a difference from the ideal value based on the steering angle as the steering wheel operation amount.

  It is considered that the ideal operation by the driver who is used to the set turning characteristics is a smooth waveform with few high-frequency components as described with reference to FIG. Therefore, the determination processing unit 114 in the present embodiment adds a low-pass filter process with a predetermined cutoff frequency to the detected value of the steering wheel operation amount.

  Further, in order to compensate for the phase delay corresponding to the filter characteristics, a value obtained by further adding a phase correction process with a predetermined correction amount to the value is regarded as an ideal value of the steering wheel operation amount. Since the change in the steering operation amount required for normal driving is considered to be a frequency component within about 1 Hz, a value of about 1 Hz is used as the cutoff frequency. A general expression of the first-order low-pass filter is as shown in Expression (6).

  Here, X is an intermediate variable for calculating the ideal value, and X (n) represents the nth X value. Ma is the steering angle of the steering wheel, and Ma (n) represents the value of the nth steering angle. f is a filter constant, T is a sampling period, and X (t) indicates the value of X at time t.

  FIG. 7 shows the relationship between the cutoff frequency and the vehicle speed. As shown in the graph of this figure, as the vehicle speed increases, the necessary steering angle and steering angular velocity of the steering wheel decrease. The filter constant f is determined so as to satisfy the relationship as shown in the figure. Although the relationship between the cut-off frequency and the vehicle speed is shown in the figure, the relationship between the cut-off frequency and the degree of turning has a similar tendency. That is, as the degree of turning increases, the steering angle and the steering angular speed of the steering wheel that are required decrease, so it is necessary to reduce the cutoff frequency. Therefore, as a modification, the degree of turning may be obtained from detected values such as the steering angle and the steering angular velocity, and the filter constant f may be determined according to the degree of turning. Alternatively, the filter constant f may be obtained with reference to a three-dimensional map that defines the relationship between the cutoff frequency, the vehicle speed, and the turning degree.

  Note that the degree of turning may be measured based on, for example, a steering angle received from the steering angle sensor 18 and values such as a yaw rate and a lateral acceleration received from a yaw rate sensor and a lateral acceleration sensor (not shown). Alternatively, the degree of turning may be determined by image recognition processing from an image in the traveling direction received from the external monitor 40.

  Assuming that the phase correction amount is t1, the equation for obtaining the ideal value Mat is as shown in Equation (7).

  Based on Expression (7), the determination processing unit 114 obtains an ideal value Mat of the steering angle.

  FIG. 8 shows the relationship between the steering angular velocity and the phase correction amount. As shown in the graph of this figure, as the steering angular velocity of the steering wheel increases, the necessary phase correction amount t1 is also increased. The steering angular velocity is a time differential value of the steering angle obtained from the steering angle sensor 18. The phase correction amount t1 is determined based on the relationship shown in the graph of this figure. Note that the phase delay to be compensated as a result of the filter processing actually varies depending on the frequency characteristics of the filter. Therefore, the phase correction amount may be determined according to the average frequency band of the necessary steering operation amount for each situation. For example, a correction amount of several tens milliseconds to several hundred milliseconds can be considered.

  The determination processing unit 114 obtains a difference δ between the steering angle Ma and the ideal value Mat. At this time, in order to allow a certain amount of error in phase correction, it is determined whether or not the absolute value of the difference between the steering angle Ma and the ideal value Mat exceeds a constant K1. When the value exceeds the constant K1, the value obtained by subtracting the constant K1 is obtained as the difference δ2 as shown in Expression (8).

  However, if it is less than or equal to the constant K1, the difference δ2 is set to zero. Then, the total sum I is obtained as shown in equation (9).

  As described above, the total sum I is determined by integration. As a modification, δ2 for each sampling time may be extracted and the total sum I may be determined by the square sum thereof.

  In order to determine the familiarity level based on the sum I of the differences δ, the determination processing unit 114 sets the total sum of the operation angles Ma as MaI, and determines the familiarity degree U based on the ratio of the total sum I to MaI by the expressions (10) and (11). )

  In this way, the reason for determining the ratio with respect to the total sum of the operation angles Ma is that, even if the total difference is the same, the evaluation of the total difference is greatly different if the overall operation amount is greatly different. A larger value of the familiarity degree U indicates that the familiarity degree is lower, and a closer familiarity degree U is to zero indicates that the familiarity degree is higher.

  FIG. 9 is a flowchart illustrating a process of determining the familiarity degree according to the first embodiment. First, the steering angle sensor 18 detects the operation angle Ma as the steering operation amount (S10), and the vehicle speed sensor 36 detects the vehicle speed (S12). The determination processing unit 114 performs low-pass filter processing on the operation angle Ma (S14), further performs phase correction processing (S16), calculates a difference δ between the operation angle Ma and the ideal value (S18), and sums the difference I Is calculated (S20).

  Here, when the accumulated operation time or the accumulated operation amount does not reach a certain amount, for example, at a timing just after the start of the vehicle (N in S22), the subsequent processing is skipped. If the accumulated operation time or the accumulated operation amount has already exceeded a certain amount (Y in S22), the subsequent processing is executed.

  When the operation amount of the steering wheel exceeds a predetermined value (Y in S24), it is determined whether there is any abnormality on the traveling road surface (S26). If there is no abnormality on the road surface (N in S26), the familiarity degree U is determined (S28). If there is an abnormality (Y in S26), the detected value in S24 is regarded as an operation for avoiding the abnormality. Skip the process of determining the familiarity level. If the detected value of the manipulated variable does not exceed the predetermined value in S24 (N in S24), the abnormality determination process in S26 is skipped.

  After the determination of the familiarity level in S28, if the familiarity level U exceeds a predetermined value (Y in S30), the driver is regarded as unfamiliar with the currently set steering characteristic, and the steering characteristic is determined. Change (S32). If the familiarity degree U does not exceed the predetermined value (N of S30), the process of S32 is skipped.

  Another example of the familiarity determination will be described in detail below. In the above description, the low-pass filter process is used. In the present embodiment, the high-pass filter process is used. The value extracted by the high-pass filter process is a relatively high-frequency component, and this component itself is a technique that considers the difference between the detected value of the manipulated variable and the ideal value.

  The process of calculating the familiarity degree U by calculating the ratio of the total amount of differences extracted by the method to the total manipulated variable and determining the familiarity degree is the same as in the first embodiment. Again, the steering wheel operating amount is based on the steering angle.

  It is considered that an operation by a driver unfamiliar with the set steering characteristics has a high frequency component and has a relatively small waveform. Therefore, the determination processing unit 114 in the present embodiment adds a high-pass filter process with a predetermined cutoff frequency to the detected value of the steering wheel operation amount.

  The process is a technique for obtaining a difference without executing extraction of an ideal value or comparison with the ideal value, and can be said to be a simple technique because the phase correction process is unnecessary. Since the change in the steering operation amount required for normal driving is considered to be a frequency component within about 1 Hz, a value of about 1 Hz is used as the cutoff frequency. A general expression of the high pass filter is as shown in Expression (12).

  For example, when discretization is performed using bilinear transformation, it is expressed by Expression (13).

  An equation for obtaining the difference δ from the ideal value by performing high-pass filter processing on the actual detected value of the steering angle is expressed by Equation (14).

  As shown in FIG. 7 in the first embodiment, the cutoff frequency needs to be lowered as the vehicle speed and the degree of turning increase, and the filter constant f is determined so as to satisfy such a relationship.

  Here, the setting of the high-pass filter processing and the cutoff frequency is based on the assumption for extracting the difference from the ideal value, and thus actually includes inaccuracy. Therefore, in order to allow some error due to such inaccuracy, it is determined whether or not the absolute value of the difference δ exceeds a constant K1. When the constant K1 is exceeded, the value obtained by subtracting the constant K1 is obtained as the difference δ2 as shown in Equation (15).

  However, if it is less than or equal to the constant K1, the difference δ2 is set to zero. Then, the total sum I is obtained as shown in equation (16).

  As described above, the total sum I is determined by integration. As a modification, δ2 for each sampling time may be extracted and the total sum I may be determined by the square sum thereof.

  In order to determine the degree of familiarity based on the total sum I of the difference δ, the determination processing unit 114 sets the total sum of the operation angles Ma as MaI, and determines the familiarity degree U from the ratio of the total I to MaI by the expressions (17) and (18). )

  A larger value of the familiarity degree U indicates that the familiarity degree is lower, and a closer familiarity degree U is to zero indicates that the familiarity degree is higher.

  FIG. 10 is a flowchart showing a process of determining the familiarity level. First, the steering angle sensor 18 detects the operation angle Ma as the steering operation amount (S50), and the vehicle speed sensor 36 detects the vehicle speed (S52). The determination processing unit 114 performs high-pass filter processing on the operation angle Ma (S54), and calculates the sum I of the differences δ between the operation angle Ma and the ideal value (S56).

  Here, when the accumulated operation time or the accumulated operation amount has not reached a certain amount, for example, at a timing immediately after the start of the vehicle (N in S58), the subsequent processing is skipped. If the accumulated operation time or the accumulated operation amount is equal to or greater than a certain amount (Y in S58), the subsequent processing is executed.

  When the operation amount of the steering wheel exceeds a predetermined value (Y in S60), it is determined whether there is any abnormality on the traveling road surface (S62). If there is no abnormality on the road surface (N in S62), the familiarity degree U is determined (S64). If there is an abnormality (Y in S62), the detected value in S60 is regarded as an operation for avoiding the abnormality. Skip the process of determining the familiarity level. If the detected value of the manipulated variable does not exceed the predetermined value in S60 (N in S60), the abnormality determination process in S62 is skipped.

  After the determination of the degree of familiarity in S64, if the degree of familiarity U exceeds a predetermined value (Y in S66), the driver is regarded as unfamiliar with the currently set turning characteristic and the turning characteristic is set. Change (S68). If the familiarity degree U does not exceed the predetermined value (N of S66), the process of S68 is skipped.

  The present invention has been described based on some embodiments. These embodiments are merely examples, and modifications such as arbitrary combinations of the embodiments, each component of the embodiments, and any combination of the processing processes are also within the scope of the present invention. It will be understood by those skilled in the art. Hereinafter, a modification is illustrated.

  In each of the above-described embodiments, the configuration in which the driver's familiarity is determined based on the steering angle as the steering wheel operation amount has been described. In the modified example, the degree of familiarity may be determined based on the operation amount other than the steering angle, for example, the steering angular velocity or the steering torque. Even in the determination of the degree of familiarity based on these parameters, a difference in tendency according to the degree of familiarity with the driver can be detected, and an effective determination result can be obtained.

  In each of the above embodiments, in principle, a steering characteristic that is a small steering angle steer is set, and when it is determined that the driver's habituation to the characteristic is low, the conventional steering characteristic is set. The example to fix was explained. In a modification, it is good also as a structure which sets the steering characteristic used as a small steering angle steer suitably as a trial, monitoring a driver's familiarity degree suitably.

  The vehicle control apparatus exemplified in the embodiment provides a method of determining a driver's familiarity with respect to steering characteristics by frequency analysis of a driver's steering input, and typically includes not only a steering vehicle's steering input but also a vehicle speed. Based on the lateral G, the yaw rate, or the vehicle state quantity including the travel position information, the calculation processing of the familiarity evaluation variable is performed, and a determination index considering the travel mode is provided.

  The vehicle control apparatus exemplified in the embodiment differs in the required steering frequency between a case where the vehicle is traveling gently such that a passenger is present in the vehicle and a case where the vehicle speed is relatively high, such as sports driving. Even in some cases, more accurate habituation determination is possible. Note that a steering angle, a steering torque, or the like may be used instead of the steering angular velocity exemplified in the embodiment.

  The vehicle control device according to the present invention is not limited to the description in the above-described embodiment, and the configuration thereof is appropriately changed within the obvious range, and the operation and processing are appropriately changed within the obvious range. Can do.

  10 .... Vehicle, 12 .... steering wheel, 14 .... steering shaft, 16 .... steering torque sensor, 18 .... steering angle sensor, 20 .... steering mechanism, 24 ...... steering motor, 34 ... Steering angle sensor, 36 ... Vehicle speed sensor, 40 ... External monitor, 44 ... Gearbox, 46 ... Steering reaction force motor, 100 ... Steering control unit, 102 ... Characteristic control unit, 104 ... Control unit 106 Steering reaction force control unit 112 Abnormality detection unit 114 Determination processing unit 116 Steering characteristic setting unit

Claims (5)

  A vehicle control device that calculates the driver's operational familiarity with the vehicle based on a vehicle state and a driver's steering speed when the vehicle turns. The vehicle control device according to claim 1,
A vehicle control device that calculates the operating familiarity of the vehicle of the driver based on the frequency characteristics of the familiarity evaluation variable Z.
However, it is assumed that the familiarity evaluation variable Z is a value corresponding to a time change of the lateral G calculated based on the operation of the driver with respect to a value related to the measured lateral G. The vehicle control device according to claim 2,
The vehicle control apparatus characterized in that the measured value related to the lateral G is the maximum value of the lateral G when the vehicle turns. In the vehicle control device according to any one of claims 1 to 3,
A vehicle control device that calculates the operating familiarity of the vehicle of the driver based on the frequency characteristics of the familiarity evaluation variable Z.
However, when the vehicle turns, the maximum value of lateral G in the turn is Gmax, the speed of the vehicle is V, the steering angular velocity of the driver is Δθ, the stability factor of the vehicle is Kh, If the wheel base of the vehicle is L and the gear ratio that is the steering angle with respect to the turning angle of the vehicle is N, the familiarity evaluation variable Z is given by the following equation (1).

In the vehicle control device according to any one of claims 1 to 3,
It is determined whether or not the vehicle is turning based on whether or not the lateral G applied to the vehicle is greater than a predetermined lateral G threshold, and the frequency characteristic of the familiarity evaluation variable Z is determined when the vehicle does not turn. The vehicle control apparatus which calculates the operation familiarity of the vehicle of the driver based on the above.
However, when the vehicle does not turn, the Gmax is the predetermined lateral G threshold, the vehicle speed is V, the driver's steering angular velocity is Δθ, and the vehicle stability factor is Kh. If the wheel base of the vehicle is L and the gear ratio that is the steering angle with respect to the turning angle of the vehicle is N, the familiarity evaluation variable Z is given by the following equation (2).

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