JP2015093569A - Steering control device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To switch controls without giving discomfort to a driver and deteriorating a function of each control in a steering control device which executes an assist control and a vehicle track control.SOLUTION: Assist deviation calculation means (21, 22) obtains a deviation (assist deviation) between detected steering torque and target steering torque. Follow-up deviation calculation means (23) obtains a deviation (follow-up deviation) between a physical amount related to steering and a target physical amount. Conversion means (24) converts at least one of the deviations so that units of the deviations match. Weighting coefficient setting means (25) sets weighting coefficients of the deviations in accordance with a degree of involvement into a vehicle track control by a driver and necessity of the vehicle track control. Deviation mixing means (26) obtains a control deviation by mixing the deviations whose units match in accordance with the weighting coefficients. Command value generation means (27) generates a command value used in motor driving so as to reduce the control deviation.

Description

  The present invention relates to a technique for controlling an assist torque and a steering angle.

  In recent years, for example, a motor rotation angle, a steering rotation angle, a yaw rate sensor, a deviation between a tire turning angle and a target value, a lateral displacement from a target position obtained by a camera, laser radar, millimeter wave radar, or the like, obtained by GPS, etc. Vehicle trajectory control that automatically controls the steering angle based on the deviation from the target trajectory and the curvature obtained by the road shape is known. In addition, based on image information from a camera that captures the front of the vehicle, the positional relationship between the traveling lane and the host vehicle is detected, and the steering angle is controlled to realize traveling along the lane. There is known a device that realizes one lane keeping control and power steering control (assist control) for generating assist torque for assisting a steering operation by a driver with one actuator (motor) (for example, , See Patent Document 1).

  In this apparatus, basically, the motor is driven based on the result of adding the required torque from the vehicle track control to the required torque from the assist control. However, when vehicle trajectory control is being performed, the influence of the assist control is suppressed by multiplying the required torque from the assist control by a coefficient greater than 0 and less than 1 so as not to easily deviate from the lane. ing.

JP-A-9-221053

  By the way, when an intervention operation by a driver, so-called driver override (DOR), is performed during vehicle trajectory control, the deviation of the actual position / actual angle with respect to the target position / angle set in the vehicle trajectory control increases. Then, in the vehicle trajectory control, a torque is generated to cancel the enlarged deviation, and the torque disturbs the operation of the driver, thereby giving the driver a sense of incongruity. In order to cancel this uncomfortable feeling, it is necessary to reduce the response of the vehicle track control. However, if the responsiveness of the vehicle track control is simply lowered, there is a problem that the original function of the vehicle track control is lowered.

  Further, depending on the situation, there is a demand to prioritize the vehicle trajectory control over the intervention operation by the driver, such as performing control to avoid danger such as a collision by the vehicle trajectory control. There is a problem that it is difficult to make such a request compatible with the above-described control switching without a sense of incongruity.

  In order to solve such problems, in a steering control device that performs both assist control and vehicle trajectory control, control switching is realized without giving a driver a sense of incongruity or reducing the function of each control. The purpose is to provide technology.

The steering control device of the present invention includes assist deviation calculation means, follow-up deviation calculation means, conversion means, weight coefficient setting means, deviation mixing means, and command value generation means.
The assist deviation calculating means obtains an assist deviation that is a deviation between a detected steering torque that is a detected value of the steering torque and a target steering torque that is a target value of assist control for reducing the steering load. The follow-up deviation calculating means obtains a follow-up deviation that is a deviation between a physical quantity having a unit other than the torque related to steering and a target physical quantity that is a target value of vehicle trajectory control using the physical quantity. The conversion means converts at least one of the two deviations so that the assist deviation calculated by the assist deviation calculation means matches the unit of the tracking deviation calculated by the tracking deviation calculation means. The weighting factor setting means sets weighting factors for assist deviation and tracking deviation according to the degree of intervention by the driver in the vehicle trajectory control and the necessity of the vehicle trajectory control. The deviation mixing unit obtains a control deviation obtained by mixing the assist deviation and the tracking deviation whose units are matched by the conversion unit according to the weighting factor set by the weighting factor setting unit. The command value generation means reduces the control deviation in accordance with the control deviation obtained by the deviation mixing means, and thereby assist command values used for driving a motor that generates assist torque based on assist control or automatic steering torque based on vehicle trajectory control. Is generated.

  According to the present invention configured as described above, the control deviation used for generating the assist command value is generated by mixing the assist deviation and the tracking deviation having the same unit, and the weighting coefficient used for generating the control deviation is generated. Is changed according to the degree of intervention of the driver with respect to the vehicle trajectory control. Note that the response of the vehicle trajectory control is improved as the follow-up deviation ratio is increased, and the response of the vehicle trajectory control is suppressed as the assist deviation ratio is increased. As a result, the assist control and the vehicle trajectory control can be seamlessly switched without causing the driver to feel uncomfortable.

  In addition, according to the present invention, since the weighting coefficient is changed according to the necessity of the vehicle trajectory control, the response of the vehicle trajectory control according to the situation that causes the necessity of the vehicle trajectory control to change. Sex can be changed. For example, in a situation where the necessity of vehicle track control is high, the vehicle track control function can be sufficiently exhibited by suppressing driver intervention by increasing the response of the vehicle track control.

  By the way, as a method for achieving both assist control and vehicle trajectory control, in addition to the method of the present invention, command values are individually generated for each of assist control and vehicle trajectory control, and the individual command values are mixed (added). A method of generating a final command value can also be considered. However, in that case, if the ratio of the command value of the vehicle trajectory control to the command value is increased (that is, the responsiveness of the vehicle trajectory control is improved), the torque overshoots at the time of steering transition (cutting, turning back, steering stop). And vibration are generated (see FIG. 7A). On the other hand, in the present invention, since such torque overshoot and vibration are suppressed, it is possible to suppress a sense of incongruity during steering due to these (see FIG. 7B).

  In addition, the code | symbol in the parenthesis described in the claim shows the correspondence with the specific means as described in embodiment mentioned later as one aspect, Comprising: The technical scope of this invention is limited is not.

  In addition to the above-described steering control device, the present invention includes various systems such as a system having the steering control device as a constituent element, a program for causing a computer to function as each means constituting the steering control device, and a steering control method. It can be realized in the form.

1 is an overall configuration diagram of an electric steering system according to an embodiment. It is a block diagram which shows the structure of EPS-ECU. It is a block diagram which shows the structure of a steering force control part. It is a graph which shows the conversion characteristic from an estimated load to a target steering torque. It is a block diagram which shows the structure of a servo control part. It is a block diagram which shows the structure of a steering input sensitive weight coefficient setting part. It is a graph which shows the result of having measured steering torque for every DOR level, (a) is a comparative example which synthesize | combines the output after servo control, (b) is an Example of this invention which mixes the deviation before servo control. .

Embodiments to which the present invention is applied will be described below with reference to the drawings.
<Overall configuration>
As shown in FIG. 1, the electric steering system 1 according to the present embodiment includes assist control for assisting a driver (operation of a steering wheel) 2 with a motor 6 and automatic steering along a target course set in a travel lane. The lane keeping control, which is one of the vehicle trajectory controls realized by the motor 6, is executed.

  The handle 2 is fixed to one end of a steering shaft 3, and a torque sensor 4 is connected to the other end of the steering shaft 3, and an intermediate shaft 5 is connected to the other end of the torque sensor 4. In the following description, the entire shaft body from the steering shaft 3 through the torque sensor 4 to the intermediate shaft 5 is also collectively referred to as a steering shaft.

  The torque sensor 4 is a sensor for detecting the steering torque Ts. Specifically, a torsion bar that connects the steering shaft 3 and the intermediate shaft 5 is provided, and a torque applied to the torsion bar is detected based on a twist angle of the torsion bar.

  The motor 6 is for generating an assist torque based on the assist control and an automatic steering torque based on the vehicle trajectory control, and its rotation is transmitted to the intermediate shaft 5 via the speed reduction mechanism 6a. That is, the speed reduction mechanism 6a is constituted by a worm gear provided at the tip of the rotating shaft of the motor 6 and a worm wheel provided coaxially with the intermediate shaft 5 in mesh with the worm gear. The rotation of the motor 6 is transmitted to the intermediate shaft 5. Conversely, when the intermediate shaft 5 is rotated by the operation of the handle 2 or the reaction force from the road surface (road surface reaction force), the rotation is transmitted to the motor 6 via the speed reduction mechanism 6a, and the motor 6 also rotates. .

  The motor 6 is formed of, for example, a brushless motor, and includes a rotation sensor such as a resolver. The rotation sensor outputs at least a steering wheel angle (steering angle) θ obtained by multiplying the motor rotation angle by the gear ratio of the speed reduction mechanism 6a. The motor rotation angle may be output as it is instead of the handle angle θ.

  The other end of the intermediate shaft 5 opposite to the end to which the torque sensor 4 is connected is connected to the steering gear box 7. The steering gear box 7 is configured by a gear mechanism including a rack and a pinion gear, and the rack teeth mesh with a pinion gear provided at the other end of the intermediate shaft 5. Therefore, when the driver turns the handle 2, the intermediate shaft 5 rotates (that is, the pinion gear rotates), and thereby the rack moves to the left and right. Tie rods 8 are attached to both ends of the rack, and the tie rods 8 reciprocate left and right together with the rack. Accordingly, the tie rod 8 pulls or pushes the knuckle arm 9 ahead, thereby changing the direction of each tire 10 that is a steered wheel.

A vehicle speed sensor 11 for detecting the vehicle speed V is provided at a predetermined part of the vehicle.
Hereinafter, the entire mechanism from the steering wheel 2 to each tire 10 to which the steering force of the steering wheel 2 is transmitted is also collectively referred to as a steering system mechanism 100.

  In the steering system mechanism 100 having such a configuration, when the steering wheel 2 is rotated by the driver's steering, the rotation is transmitted to the steering gear box 7 via the steering shaft 3, the torque sensor 4, and the intermediate shaft 5. Then, in the steering gear box 7, the rotation of the intermediate shaft 5 is converted into the left-right movement of the tie rod 8, and the left and right tires 10 are steered by the movement of the tie rod 8.

The LKA (lane keep) -ECU 16 is operated by electric power from an in-vehicle battery (not shown), and detects the driving lane and the position of the host vehicle in the driving lane from an image in front of the vehicle imaged by an in-vehicle camera (not shown). A target trajectory is set based on the result. Further, a target rudder angle θ ^* , which is a target value of the steering wheel angle for traveling along the target track, is set based on the detected value of the vehicle speed and the rudder angle. Since the process for setting the target rudder angle θ ^* is well known in the lane keep control, the description thereof is omitted here.

Further, the LKA-ECU 16 detects various targets (obstacles, own lanes, vehicles traveling in adjacent lanes, etc.) existing in the vehicle travel environment from the above-mentioned image in front of the vehicle, and the reliability of the target recognition state. Further, the degree of risk is estimated from the relationship between the detected target and the vehicle (relative speed, distance, whether the lane is the same, etc.). For the reliability and the risk, a known method in vehicle control can be used. Further, in accordance with the reliability and the risk level, a DOR level Lv (a numerical value of 1 to 4 in the present embodiment) that becomes larger as the reliability level and the risk level are higher is set, and the target rudder described above is set. Output to EPS-ECU 15 together with angle θ ^* .

The EPS (Electric Power Steering) -ECU 15 is operated by electric power from a vehicle battery (not shown), the target steering angle θ ^* , the DOR level Lv obtained by the LKA-ECU 16, the steering torque Ts detected by the torque sensor 4, Based on the steering wheel angle θ from the motor 6 and the vehicle speed V detected by the vehicle speed sensor 11, an assist command Ta ^* , which is a current command value for generating the assist torque and the automatic steering torque, is calculated. Then, by applying a driving voltage Vd corresponding to the assist command Ta ^* to the motor 6, an assist torque and an automatic steering torque are generated.

That is, the EPS-ECU 15 controls the steering characteristics by controlling the motor 6 with the drive voltage Vd, and thus controls the steering system mechanism 100 driven by the motor 6.
<EPS-ECU>
As shown in FIG. 2, the EPS-ECU 15 includes a steering force control unit 21, an assist deviation calculation unit 22, a tracking deviation calculation unit 23, a dimension conversion unit 24, a steering input sensitive weight coefficient setting unit 25, an arbitration unit 26, and a servo control. A unit 27 and a motor drive circuit 28; Of these, each part excluding the motor drive circuit 28 is realized by a CPU (not shown) included in the EPS-ECU 15 executing a predetermined control program. However, the realization of these units by software is merely an example, and at least a part of them may be realized by hardware such as a logic circuit.

The steering force control unit 21 generates a target steering torque Ts ^* based on the assist command Ta ^* , the steering torque Ts, and the traveling speed (vehicle speed) V of the host vehicle. Specifically, as shown in FIG. 3, a load estimator 211 and a target steering torque calculator 212 are provided.

The load estimator 211 includes an adder 211a that adds the assist command Ta ^* and the steering torque Ts, and a low-pass filter (LPF) 211b that extracts a band component equal to or lower than a predetermined frequency from the addition result. The LPF 211b Is output as an estimated load Tx that is an estimated value of the road surface load. Since the driver mainly operates by relying on the steering reaction force information of 10 Hz or less, the LPF 211 b passes (extracts) the frequency component of approximately 10 Hz or less so as to block the frequency component higher than 10 Hz. Is set.

The target steering torque calculator 212 calculates a target steering torque Ts ^* , which is a target value of the steering torque, based on the estimated load Tx estimated by the load estimator 211 and the vehicle speed V, as shown in FIG. Calculate using. However, the map shown in FIG. 4 shows the characteristics of the function when the estimated load Tx is a positive value, and the function when the estimated load Tx is a negative value is symmetrical to the graph of FIG. Have the characteristics

Returning to FIG. 2, the assist deviation calculator 22 calculates an assist deviation ΔTs that is the difference between the steering torque Ts and the target steering torque Ts ^* . The follow-up deviation calculator 23 calculates a follow-up deviation Δθ, which is the difference between the steering wheel angle θ and the target rudder angle θ ^* .

  The dimension conversion unit 24 calculates a follow-up deviation torque converted value ΔTd obtained by converting the follow-up deviation Δθ into a torque. In this calculation, the dimension (unit) of the tracking deviation Δθ is converted to the dimension (unit) of the assist deviation ΔTs based on the relationship between the force applied to one end of the torsion bar and the torsion angle (torsion rigidity). This conversion formula can be determined as appropriate based on the structure around the torsion bar, and a detailed description thereof will be omitted. The dimension converter 24 also performs phase compensation for absorbing the difference between the angle and the torque phase.

  The arbitration unit 26 obtains the control deviation ΔT using the equation (1), with the assist deviation ΔTs and the tracking deviation torque converted value ΔTd according to the steering input sensitive weight coefficient G set by the steering input sensitive weight coefficient setting unit 25. However, G takes a value of 0-1.

ΔT = (1−G) × ΔTs + G × ΔTd (1)
That is, when G = 0, only assist control is executed, and when G = 1, only vehicle trajectory control is executed. As G is smaller, assist control has priority, and as G is larger, vehicle trajectory control is performed. Priority will be given.

The servo control unit 27 generates an assist command Ta ^* for generating an assist torque (also referred to as an assist amount) such that the control deviation ΔT becomes 0 based on the control deviation ΔT. Specifically, as shown in FIG. 5, the servo control unit 27 includes a proportional controller 271 that generates a proportional component proportional to the control deviation ΔT, and an integral that generates an integral component proportional to the time integral of the control deviation ΔT. A controller 272, a differential controller 273 that generates a differential component proportional to the derivative of the control deviation ΔT, and a command value calculator 274 that generates an assist command Ta ^* by adding the proportional component, the integral component, and the differential component. And so-called PID control. In FIG. 5, Kp is a proportional component gain (proportional gain), Ki is an integral component gain (integral gain), Kd is a differential component gain (differential gain), s is a Laplace operator, and s / (τs + 1) 2 is Represents a pseudo differential operation.

Returning to Figure 2, the motor drive circuit 28, based on the assist command Ta ^*, the driving voltage Vd to the motor 6 such that the torque corresponding to the assist command Ta ^* (assist torque and the automatic steering torque) is applied to the steering shaft Apply. Specifically, the assist command Ta ^* is set as the target current, and the drive voltage Vd is feedback-controlled so that the energization current Im flowing through the motor 6 matches the target current, thereby generating a desired torque for the steering shaft. . Note that such a motor drive circuit 28 is a known technique (for example, see Japanese Patent Application Laid-Open No. 2013-52793), and a detailed description thereof will be omitted.

  The steering input sensitive weight coefficient setting unit 25 sets the steering input sensitive weight coefficient G based on the steering torque Ts and the DOR level Lv. As shown in FIG. 6, the LPF 251, the absolute value calculator 252, the operating point A shift calculator 253 and a weight coefficient calculator 254 are provided.

  The LPF 251 is a low-pass filter that removes noise components other than the intervention operation by the driver, such as a road surface disturbance superimposed on the steering torque Ts, from the steering torque Ts. The absolute value calculator 252 obtains the absolute value | Ts | of the steering torque from which the noise output from the LPF 251 is removed.

  The operating point shift calculator 253 uses the shift calculation map or function equation prepared in advance to obtain the steering coefficient absolute value | Ts | as an input and obtain a weighting coefficient calculating torque Tg as an output. The shift calculation map has a characteristic that the output Tg increases as the input | Ts | increases. However, the characteristic shifts according to the DOR level Lv, and the dead zone for the input | Ts | is set to increase as the DOR level increases. That is, when the DOR level Lv is 1 (lowest), there is no dead zone, and the output Tg = α × | Ts | is always proportional to the input | Ts | (where α = 1). When the DOR level Lv is k (k> 1), the boundary value of the dead zone is Nk, Tg = 0 when 0 ≦ | Ts | ≦ Nk, and Tg = α × (| Ts | − when Tk |> Nk. Nk).

  The weighting factor calculator 254 uses a weighting factor calculation map prepared in advance, receives the weighting factor calculation torque Tg as an input, obtains an output steering input sensitive weighting factor G, and outputs the result to the arbitration unit 26. . In the weighting factor calculation map, G = 1 when Tg = 0, G = 0 when Tg ≧ A, and 0 <G <1 in the range of 0 <G <1, and G increases as Tg increases. It is set to be smaller. Note that the shape of the graph representing the characteristics of the map when 0 <Tg <A is sufficient as long as G decreases according to Tg, and the decreasing tendency is not limited to a linear one. For example, the shape may be a quadratic function.

  In other words, the steering input sensitive weighting coefficient G set by the steering input sensitive weighting coefficient setting unit 25 becomes the maximum value G = 1 when the absolute value | Ts | of the steering torque is zero. At this time, the control deviation ΔT generated by the arbitration unit 26 is equal to the follow-up deviation torque converted value ΔTd, and only the vehicle track control is executed.

  Further, the steering input sensitivity weight coefficient G approaches 0 as the absolute value | Ts | of the steering torque increases, and accordingly, the ratio of the tracking deviation torque converted value ΔTd to the control deviation ΔT decreases, and the assist deviation ΔTs increases. The rate increases. That is, as the absolute value | Ts | of the steering torque increases, the influence of the assist control increases, and when the steering input sensitive weight coefficient becomes the minimum value G = 0, the control deviation ΔT becomes equal to the assist deviation ΔTs, and the assist Only control will be executed.

Further, the steering input sensitivity weighting coefficient G increases as the DOR level Lv increases, and the steering torque absolute value | Ts | at which the steering input sensitivity weighting coefficient starts to decrease from G = 1 increases. If the rotation operation is not performed, the steering input sensitive weight coefficient G cannot be directed to a value smaller than 1. In other words, vehicle trajectory control is prioritized and is less likely to receive driver intervention.
When the vehicle trajectory control is being executed at the target rudder angle θ ^* = 0 [deg], the steering angle θ detected when the driver steers the steering wheel and ramps the range of ± 30 [deg]. The steering torque Ts was obtained by simulation. FIG. 7B shows the simulation result of the present embodiment, and FIG. 7A shows the simulation result of the comparative example. In each case, the DOR level Lv is changed in four stages of 1 to 4. In the comparative example, the output results of the servo control of the base assist command that is the result of servo-controlling the assist deviation ΔTs and the tracking command that is the result of servo-controlling the tracking deviation Δθ are respectively expressed as steering input sensitive weight coefficients G The assist command Ta ^* is a mixture of the above.

From the figure, it is understood that when the DOR level Lv is increased, the steering torque when the driver performs an intervention operation becomes heavy, that is, the maintenance force to the target rudder angle θ ^* in the vehicle trajectory control becomes strong. Further, in the comparative example, torque vibration occurs at the time of steering transition (cutting: A in the figure, turning back: B in the figure, steering stop: C in the figure). It can be seen that torque vibration is suppressed.

<Effect>
As described above, in the present embodiment, the control deviation ΔT is generated by mixing the assist deviation ΔTs and the tracking deviation torque conversion value ΔTd, and the steering input sensitive weight coefficient G used to generate the control deviation ΔT is determined as follows. In accordance with the absolute value | Ts | of the steering torque, the ratio of the assist deviation ΔTs in the control deviation ΔT increases as | Ts | increases, that is, as the degree of intervention by the driver in the vehicle trajectory control increases. I am letting. As a result, the assist control and the vehicle trajectory control can be seamlessly switched without causing the driver to feel uncomfortable.

  Further, in the present embodiment, the steering input sensitive weight coefficient G is changed according to the DOR level Lv representing the degree of necessity of vehicle trajectory control. The higher the DOR level Lv, the steering when the driver performs an intervention operation. The torque is increased. For this reason, in the situation where the necessity of vehicle track control is high, the driver's intervention is suppressed and the function of the vehicle track control can be sufficiently exhibited.

Further, in the present embodiment, torque overshoot and vibration that occur at the time of steering transition are suppressed, so that the uncomfortable feeling at the time of steering caused by these can be suppressed.
<Other embodiments>
As mentioned above, although embodiment of this invention was described, it cannot be overemphasized that this invention can take a various form, without being limited to the said embodiment.

  (1) Although the case where lane keep control is performed as vehicle trajectory control has been illustrated in the above embodiment, the present invention is not limited to this. For example, motor rotation angle, steering rotation angle, yaw rate sensor, tire turning angle, and target Steering automatically based on deviation from values, lateral displacement from target position obtained by camera, laser radar, millimeter wave radar, etc., deviation from target locus obtained by GPS, etc., deviation from curvature obtained by road shape Any device that controls the corner may be used.

  (2) In the above embodiment, the dimension conversion unit 24 converts the follow-up deviation (deviation of the target physical quantity) Δθ so as to match the dimension (unit) of the assist deviation ΔTs, but conversely follows the assist deviation ΔTs. Conversion may be performed so as to match the dimension of the deviation Δθ. Moreover, you may convert both into the physical quantity of another dimension which is neither.

  (3) In the above embodiment, the steering input sensitive weight coefficient setting unit 25 increases the dead band of the steering torque Ts as the DOR level Lv increases. However, the present invention is not limited to this, and the DOR level Lv is not limited to this. As long as it is large, that is, as the degree of necessity of vehicle track control is high, it is only necessary that the decrease in the weight of the tracking deviation with respect to the steering torque Ts is suppressed.

  (4) Each component of the present invention is conceptual and is not limited to the above embodiment. For example, the functions of one component may be distributed to a plurality of components, or the functions of a plurality of components may be integrated into one component. Further, at least a part of the configuration of the above embodiment may be replaced with a known configuration having the same function. In addition, at least a part of the configuration of the above embodiment may be added to or replaced with the configuration of the other embodiment.

  DESCRIPTION OF SYMBOLS 1 ... Electric steering system 2 ... Handle 3 ... Steering shaft 4 ... Torque sensor 5 ... Intermediate shaft 6 ... Motor 6a ... Deceleration mechanism 7 ... Steering gear box 8 ... Tie rod 9 ... Knuckle arm 10 ... Tire 11 ... Vehicle speed sensor 21 ... Steering Force control unit 22 ... assist deviation calculation unit 23 ... tracking deviation calculation unit 24 ... dimension conversion unit 25 ... steering input sensitive weight coefficient setting unit 26 ... arbitration unit 27 ... servo control unit 28 ... motor drive circuit 100 ... steering system mechanism 211 ... Load estimator 211a ... adders 211b, 251 ... low pass filter (LPF) 212 ... target steering torque calculator 252 ... absolute value calculator 253 ... operating point shift calculator 254 ... weight coefficient calculator 271 ... proportional controller 272 ... integral Controller 273 ... Differential control Vessel 274 ... command value computing unit

Claims (3)

Assist deviation calculating means (21, 22) for obtaining an assist deviation which is a deviation between a detected steering torque which is a detected value of the steering torque and a target steering torque which is a target value of assist control for reducing the steering load;
Follow-up deviation calculating means (23) for obtaining a follow-up deviation which is a deviation between a physical quantity having a unit other than torque related to steering and a target physical quantity serving as a target value of vehicle trajectory control using the physical quantity;
A conversion means (24) for converting at least one of the two deviations so that the assist deviation obtained by the assist deviation computing means and the unit of the tracking deviation obtained by the following deviation calculating means coincide with each other;
Weight coefficient setting means (25) for setting a weight coefficient of the assist deviation and the tracking deviation according to the degree of intervention of the vehicle track control by the driver and the necessity of the vehicle track control;
Deviation mixing means (26) for obtaining a control deviation in which the assist deviation and the tracking deviation whose units are matched by the conversion means are mixed according to the weighting factor set by the weighting factor setting means;
By reducing the control deviation in accordance with the control deviation obtained by the deviation mixing means, an assist command value used for driving a motor that generates assist torque based on the assist control or automatic steering torque based on the vehicle trajectory control is generated. Command value generating means (27);
A steering control device comprising:   The weighting factor setting means decreases the weighting factor of the follow-up deviation as the input amount indicating the degree of intervention in the vehicle trajectory control by the driver increases, and increases the necessity of the vehicle trajectory control. The steering control device according to claim 1, wherein a decrease in the weight of the tracking deviation with respect to the force is suppressed.   The degree of necessity of the vehicle trajectory control depends on at least one of the reliability of the recognition state of the target existing in the vehicle driving environment and the risk estimated from the relationship between the target and the host vehicle. The steering control device according to claim 1, wherein the steering control device is set to increase as the degree or the degree of risk increases.

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