JP3794173B2 - Power steering control device - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a power steering control device that controls an assist force for steering a vehicle in accordance with a traveling state.
[0002]
[Prior art]
In recent years, a route guidance device (so-called car navigation system) that detects a traveling position of a vehicle and displays the position on a road map, displays a traveling direction of the vehicle, and instructs a traveling direction of the vehicle by voice. It is becoming popular.
[0003]
Furthermore, in the case of an instruction by display or voice, since the driver may miss this instruction and the vehicle cannot be guided, an apparatus for automating or semi-automating the steering of the vehicle has been proposed.
[0004]
For example, Japanese Patent Application Laid-Open No. 7-231991 discloses a technique for determining the shape of a road and automatically controlling the steering of the vehicle so that the vehicle travels along the road.
[0005]
JP-A-8-263790 discloses a method for estimating the yaw rate when the vehicle travels based on the road shape, and steering the vehicle so that the deviation between the estimated yaw rate and the actually detected yaw rate is small. A technique of automatically controlling the above is disclosed.
[0006]
However, in any of the above conventional devices, the steering of the vehicle is controlled regardless of the will of the driver or in preference to the will of the driver, so that the driver is forced to steer unexpectedly. There is.
[0007]
[Problems to be solved by the invention]
As described above, conventionally, the traveling direction of the vehicle is displayed or instructed by voice. However, the driver may miss this instruction and the vehicle may not be guided.
[0008]
In addition, when the steering of the vehicle is automatically controlled, the steering of the vehicle is controlled regardless of the driver's intention or in preference to the driver's intention. There was a problem of being forced.
[0009]
Accordingly, an object of the present invention is to provide a power steering control device capable of reliably guiding a vehicle along a road while always giving priority to a driver's will.
[0010]
[Means for Solving the Problems]
  In order to solve the above-described problems, a power steering control device according to the present invention includes an assist unit that gives an assist force to steering of a vehicle, a travel route information output unit that outputs information on the travel route of the vehicle, and the travel Based on the travel route information from the route information output means, target steering angle calculation means for obtaining the target steering angle of the vehicle, and steering in the direction of the target steering angle obtained by the target steering angle calculation means The assist force given to the steering in the direction opposite to the target steering angle is smaller than the assist force given byBeforeControl the assist meansAs the difference between the actual steering angle of the vehicle and the target steering angle is larger, the assist force applied to the steering to the target steering angle and the target steering angle are steered in the opposite direction. Increase the difference in assist power given toRegardless of whether the steering direction of the vehicle is the direction of the target steering angle obtained by the target steering angle calculating means and the case where the target steering angle is the opposite direction, Second control means for controlling the assist means so that an assist force is applied to the steering of the vehicle, and control of the assist means by the first control means when the steering angular velocity or the steering torque is a predetermined value or less are selected. And a first assist control mode selecting means for selecting control of the assist means by the second control means when the steering angular velocity or the steering torque is greater than a predetermined value.
[0011]
  In the present invention configured as described above, when the steering angular velocity or the steering torque is equal to or less than a predetermined value, the control of the assist means by the first control means is selected, and therefore, given to the steering in the direction of the target steering angle. Compared to the assist force, the assist force applied to the steering in the direction opposite to the target steering angle is smaller, and compared to the operation force required for steering in the direction of the target steering angle, the target steering angle and Increases the operating force required for steering in the reverse direction, making it difficult to perform steering in the reverse direction. On the other hand, the operating force required for steering in the direction of the target steering angle is smaller than the operating force required for steering in the direction opposite to the direction of the target steering angle. Steering can be performed easily. Therefore, the driver can change the actual steering angle to the target steering angle by a simple operation of steering to the side where the operation force is small.
  Further, when the steering angular velocity or the steering torque is larger than the predetermined value, the control of the assist means by the second control means is selected, so that the steering direction of the vehicle is the direction of the target steering angle or opposite to the target steering angle. Regardless of the direction, an assist force is applied to the steering operation by the driver, and the driver's steering operation is normally subjected to assist control. Thus, steering by the driver for emergency avoidance is not hindered by the control by the first control means.
  Further, in the control of the assist means by the first control means, the more the vehicle steering angle deviates from the target steering angle, the opposite to the target steering angle compared to the operating force required for steering in the direction of the target steering angle. The operating force required to steer the vehicle increases. For this reason, the driver can recognize that the actual steering angle is greatly deviated from the target steering angle.
[0012]
In one embodiment, the assist means applies assist force by an electric motor.
[0013]
In this case, since the assist force is increased or decreased by controlling the electric motor, the control can be easily performed.
[0018]
  In one embodiment,carSpeed is a predetermined speedBigger thanSometimesThe control of the assist means by the second control means is selected, and the control of the assist means is selected to follow the selection of the control of the assist means by the first assist control mode selection means when the vehicle speed is equal to or lower than a predetermined speed. Assist control mode selection means is provided.
[0019]
  That meansVehiclePredetermined speedBigger thanWhen the vehicle is traveling at a speed, it is determined that the vehicle is traveling stably, and the assist force is not reduced even when steering is performed in the direction opposite to the direction of the target steering angle, thereby simplifying the control.
[0020]
  In one embodiment,in frontThe difference between the actual steering angle of the vehicle and the target steering angleLess than a fixed valueWhenWhen the control of the assist means by the second control means is selected and the difference between the actual steering angle of the vehicle and the target steering angle is greater than or equal to a predetermined value, the control of the assist means by the first assist control mode selection means is followed. Thus, the third assist control mode selection means for selecting the control of the assist means is provided.
[0021]
That is, when the required steering angle is small, it is considered that the stable running is almost performed, and the assist force is not reduced even when steering is performed in the direction opposite to the target steering angle, and the control is simplified.
[0022]
DETAILED DESCRIPTION OF THE INVENTION
Embodiments of the present invention will be described below with reference to the accompanying drawings.
[0023]
FIG. 1 shows a first embodiment of a power steering control device of the present invention.
[0024]
The steering device 1 has a steering shaft 10 that supports a steering wheel 11. The steering shaft 10 includes an input shaft 10a connected to the steering wheel 11 side and an output shaft 10b connected to the steering wheel (not shown) side. The input shaft 10a and the output shaft 10b are connected by a torsion bar (not shown) so as to be relatively rotatable within a predetermined angle range.
[0025]
The torque sensor 12 detects a steering torque T generated by the rotation of the steering wheel 11. The steering torque T can be detected based on, for example, a relative rotational displacement between the input shaft 10a and the output shaft 10b. The output of the torque sensor 12 is supplied to an electronic control unit (hereinafter referred to as ECU) 13.
[0026]
The vehicle speed sensor 21 detects the rotational speed of the wheel corresponding to the vehicle speed V. The output of the vehicle speed sensor 21 is supplied to the ECU 13.
[0027]
The ECU 13 supplies a current I to the motor 14 in accordance with the steering torque T detected by the torque sensor 12 and the vehicle speed V detected by the vehicle speed sensor 21 as will be described later. The motor 14 is driven according to the current I, and applies assist torque to the output shaft 10 b via the pinion gear 16 and the ring gear 17. The pinion gear 16 is attached to the rotating shaft of the motor 14. The ring gear 17 is attached to the output shaft 10b. The pinion gear 16 and the ring gear 17 mesh with each other.
[0028]
The motor 14 is driven to apply an assist force according to the steering torque T. Further, the motor 14 changes the motor rotation angle to the steering angle θ._mAnd output to the ECU 13.
[0029]
The steered wheel turning mechanism 20 is connected to steered wheels (not shown), and converts the rotation of the output shaft 10b into motion in the axial direction. As the output shaft 10b rotates, the displacement member of the steering wheel turning mechanism 20 shifts left and right, thereby turning the steering wheel.
[0030]
Furthermore, a route guidance device 22 and a vehicle information collection device 23 are connected to the ECU 13.
[0031]
The route guidance device 22 is a so-called car navigation system, stores a road map, and displays the position of the vehicle on the road map. Specifically, an area near the vehicle is extracted from the road map, and the road map and the position of the vehicle in this area are displayed on the display screen. Further, the route guidance device 22 notifies the ECU 13 of information related to the position of the vehicle and the road ahead of the vehicle.
[0032]
The vehicle information collection device 23 receives information from the vehicle information and communication system, information from an artificial satellite, and the like, extracts information about a road ahead of the vehicle from the received information, and notifies the ECU 13 of the information.
[0033]
The information related to the road ahead of the vehicle notified from the route guidance device 22 and the vehicle information collection device 23 to the ECU 13 is, for example, the rotation radius of the road ahead of the vehicle, the temperature, the weather, the road surface material M (road surface μ), and the like.
[0034]
In the first embodiment having such a configuration, the control of the flowchart shown in FIG. 2 is performed to generate an assist force for the rotation of the steering shaft 10, thereby appropriately assisting the force for operating the steering wheel 11. Further, just by rotating the steering wheel 11 in the direction in which the operating force of the left and right rotational directions is small, the assisting force for steering in the right direction and the steering force in the left direction so that the vehicle travels along the road. Appropriate difference is given to assist power.
[0035]
Next, the assist force control process in the first embodiment will be described in detail with reference to the flowchart of FIG. Hereinafter, the value related to steering is considered to be positive in the right direction.
[0036]
First, the ECU 13 detects the steering torque T detected by the torque sensor 12, the vehicle speed V detected by the vehicle speed sensor 21, and the steering angle θ detected by the motor 14._mAt the same time, the turning radius R of the road ahead of the vehicle, temperature T, weather W, road surface material M (road surface μ), etc. are input from the route guidance device 22 and the vehicle information collection device 23 (steps 101 and 102). .
[0037]
The ECU 13 determines the vehicle speed V and the steering angle θ obtained in step 101._mFor example, a characteristic curve of the assist force F with respect to the steering torque T as shown in the graph of FIG. 3 is obtained (step 103).
[0038]
In the graph of FIG. 3, the horizontal axis indicates the steering torque T, and the vertical axis indicates the assist force F. As is apparent from this graph, the assist force F is zero as long as the steering torque T is maintained at zero. In any of the left and right steering, the assist force F increases as the steering torque T increases.
[0039]
Next, the ECU 13 calculates the vehicle speed V obtained in step 101, the rotation radius R of the road ahead of the vehicle obtained in step 102, the temperature T, the weather W, the road material M (road surface μ), and the like (1 ) To obtain the target steering angle θ (step 104).
[0040]
θ = f_R(R) + f_V(V) + f_C(T, W, M) + f_g(G) ... (1)
Where f_R(R) is a function of the radius of rotation R, f_V(V) is a function of vehicle speed V, f_C(T, W, M) is a function of temperature T, weather W, and road surface material M (road surface μ), f_g(G) is an error correction term.
[0041]
In the above formula (1), f_R(R) has the largest specific gravity, and other f_V(V), f_C(T, W, M) and f_g(G) is added for correction. f_R(R) is expressed by the following equation (2) on the condition that L << R, where L is a wheel base as shown in FIG.
[0042]
f_R(R) ≈αL / R (2)
F_R(R), f_V(V), f_C(T, W, M) and f_g(G) is gradually optimized every time the target steering angle θ is repeatedly obtained. That is, the actual steering angle θ_mAnd the target steering angle θ are expressed as shown in the following equation (3), so that every time the target steering angle θ is repeatedly obtained, the actual steering angle θ_mAnd the target steering angle θ, and the difference is fed back to each term according to the degree of contribution of each term in the above equation (1), the function of each term can be optimized.
[0043]
θ_m−θ = Δf_R+ Δf_V+ Δf_C+ Δf_g  ... (3)
When the target steering angle θ is obtained in this way, the ECU 13 determines the current steering angle θ._mIt is determined whether or not the difference obtained by subtracting the target steering angle θ from the vehicle is positive, that is, whether or not the steering wheel 11 needs to be rotated in the right direction in order to drive the vehicle along the road (step). 105). When it is necessary to rotate the steering wheel 11 in the right direction (step 105, YES), the ECU 13 changes the characteristic curve of the assist force F obtained in step 103 as shown in the graph of FIG. The assist force F for leftward steering is set to 0 (step 106).
[0044]
If it is not necessary to rotate the steering wheel 11 to the right (step 105, NO), the current steering angle θ_mIt is determined whether or not the difference obtained by subtracting the target steering angle θ from the negative is negative, that is, whether or not the steering wheel 11 needs to be rotated leftward in order to drive the vehicle along the road (step) 107). If the steering wheel 11 is to be rotated leftward (step 107, YES), the ECU 13 changes the characteristic curve of the assist force F obtained in step 103 as shown in the graph of FIG. The assist force F for the steering to 0 is set to 0 (step 108).
[0045]
Further, when it is not necessary to rotate the steering wheel 11 in the left direction (step 107, NO), the ECU 13 does not change the assist force F obtained in step 103 (step 109). Thereafter, an assist force F is obtained based on the selected characteristic curve and steering torque T, and a current is supplied to the motor 14 (step 110).
[0046]
That is, if it is necessary to rotate the steering wheel 11 in the right direction in order to drive the vehicle along the road, the assist force F for steering the vehicle in the left direction as in the characteristic curve shown in the graph of FIG. If the steering wheel 11 needs to be rotated in the left direction, the assist force F for steering the vehicle in the right direction is set to 0 as shown in the graph of FIG. If the rotation is not performed in any direction, the assist force F is not changed as in the characteristic curve shown in the graph of FIG.
[0047]
Thus, in the state where any one of the characteristic curves of FIGS. 3, 5 and 6 is selected as the assist force F, the ECU 13 obtains the assist force F corresponding to the actual steering torque T based on the selected characteristic curve. The assist force F is generated by controlling the current I to the motor 14. As a result, if it is necessary to rotate the steering wheel 11 in the right direction in order to drive the vehicle along the road, the assist force F acts only on the right direction rotation of the steering wheel 11 and the left direction rotation occurs. Since the assist force does not act, the leftward rotation of the steering wheel 11 becomes heavy. Further, if it is necessary to rotate the steering wheel 11 in the left direction, the assist force F acts only on the left rotation of the steering wheel 11 and the assist force does not act on the right rotation. The rightward rotation becomes heavy. Furthermore, if it is not necessary to rotate the steering wheel 11, the assist force F acts in any of the left and right directions. Therefore, the driver can perform the simple operation of rotating the steering wheel 11 to the side where the operation force is small, thereby performing the current steering angle θ._mCoincides with the target steering angle θ, and the vehicle can travel along the road. In addition, like the display and voice, the driver does not miss it, and the steering of the vehicle is not controlled in preference to the will of the driver.
[0048]
In the present embodiment, a method of selecting a characteristic curve is adopted, but this is not particularly necessary, and the assist force based on the current steering torque T from the basic characteristic curve of the assist force F (FIG. 3). A method of obtaining F and correcting the assist force F as appropriate may be used. Further, the characteristic curve (FIG. 3) of the basic assist force F is only based on the steering torque T, and is corrected later according to the vehicle speed V-steering angle θ and the like (for example, after steps 106, 108, 109). You may do it.
[0049]
Furthermore, “0” in steps 105 and 107 may be appropriately given a certain width that can be determined as “0”. In addition, various methods for obtaining the target steering angle θ are conceivable regardless of the present embodiment. For example, not only route information but also vehicle information can be incorporated.
[0050]
Next, a second embodiment of the power steering control device of the present invention will be described.
[0051]
In the second embodiment, as in the first embodiment, assuming the steering device 1 as shown in FIG. 1, the control of the flowchart shown in FIG. 7 is performed, and the assist force F and the left direction for steering in the right direction are controlled. Appropriate difference is given to the assist force F with respect to the steering.
[0052]
First, the ECU 13 controls the steering torque T, the vehicle speed V, and the steering angle θ as in steps 101 and 102 in FIG._mAt the same time, a turning radius R of the road ahead of the vehicle, temperature T, weather W, road surface material M (road surface μ), and the like are input (steps 201 and 202).
[0053]
Then, the ECU 13 determines the vehicle speed V and the steering angle θ obtained in step 201._mBased on the above, a characteristic curve of the assist force F with respect to the steering torque T as shown in the graph of FIG. 3 is obtained (step 203).
[0054]
Next, the ECU 13 determines the vehicle speed V obtained in step 201, the rotation radius R of the road ahead of the vehicle obtained in step 202, the temperature T, the weather W, the road surface material M (road surface μ), and the like (1) ) To obtain the target steering angle θ (step 204).
[0055]
Thereafter, the ECU 13 determines the vehicle speed V (step 205), the steering angular velocity θ_m'(Step 206) and actual steering angle θ_mAnd a determination on the absolute value of the difference between the target steering angle θ (step 207).
[0056]
  Here, the vehicle speed V is equal to or lower than a predetermined speed Vo (step 205, NO), and the steering angular speed θm ′ is predetermined.Angular velocityAngle θo ′ or less (step 206, NO), and the absolute value of the difference between the actual steering angle θm and the target steering angle θ is a predetermined angle θ1.more thanIf so (step 207, NO), the ECU 13 determines whether or not the difference obtained by subtracting the target steering angle θ from the current steering angle θm is positive, that is, in order to drive the vehicle along the road, the steering wheel It is determined whether or not it is necessary to rotate 11 to the right (step 208). When it is necessary to rotate the steering wheel 11 in the right direction (step 208, YES), the ECU 13 shows the characteristic curve of the assist force F obtained in step 203 in the graph of FIG.LikeAnd the assist force F for the leftward steering of the vehicle is decreased (step 209). At this time, the larger the difference between the actual steering angle θm and the target steering angle θ, the smaller the slope of the left half of the characteristic curve shown in the graph of FIG. 8 approaches the characteristic curve shown in the graph of FIG. The degree of reduction of the assist force F for the leftward steering is increased.
[0057]
  If the steering wheel 11 does not need to be rotated in the right direction (step 208, NO), whether or not the steering wheel 11 needs to be rotated in the left direction in order to drive the vehicle along the road. Is determined (step 210). When it is necessary to rotate the steering wheel 11 leftward (step 210, YES), the ECU 13 shows the characteristic curve of the assist force F obtained in step 203 in the graph of FIG.LikeAnd the assist force F for steering the vehicle in the right direction is reduced (step212). At this time, the larger the difference between the actual steering angle θm and the target steering angle θ, the smaller the slope of the right half of the characteristic curve shown in the graph of FIG. 9 approaches the characteristic curve shown in the graph of FIG. The degree of reduction of the assist force F for the leftward steering is increased.
[0058]
  Further, when it is not necessary to rotate the steering wheel 11 in the left direction (step 210, NO), the ECU 13 does not change the assist force F obtained in step 203 (step211). Thereafter, the assist force F is obtained based on the set characteristic curve and the steering torque T, and a current is supplied to the motor 14. (Step 213)
[0059]
That is, if it is necessary to rotate the steering wheel 11 in the right direction in order to drive the vehicle along the road, the assist force F for steering the vehicle in the left direction as in the characteristic curve shown in the graph of FIG. If the steering wheel 11 needs to be rotated in the left direction, the assist force F for steering the vehicle in the right direction is reduced as shown in the graph of FIG. If the rotation is not performed in any direction, the assist force F is not changed as in the characteristic curve shown in the graph of FIG.
[0060]
Thus, in the state where any one of the characteristic curves in FIGS. 3, 8, and 9 is selected as the assist force F, the ECU 13 obtains the assist force F corresponding to the actual steering torque T based on the selected characteristic curve. The assist force F is generated by controlling the current I to the motor 14. As a result, the vehicle can be driven along the road by a simple operation of rotating the steering wheel 11 to the side where the operation force is small. Moreover, the actual steering angle θ_mAs the difference between the target steering angle θ and the target steering angle θ increases, the assist force F for steering in a direction opposite to the target steering angle θ decreases, so that the driver can change the actual steering angle θ according to the operating force of the steering wheel 11._mAnd the target steering angle θ can be recognized to be large.
[0061]
  On the other hand, when the vehicle speed V exceeds the predetermined speed Vo, it is determined that the vehicle is traveling stably (step 205, YES), and the ECU 13 does not change the assist force F obtained in step 203 (step 205).211). This simplifies the control.
[0062]
  Further, the steering angular velocity θm ′ is predetermined.Angular velocityDegree θo ’Bigger than(Step 206, YES), there is a possibility that rapid steering is being performed for emergency avoidance, so steering for emergency avoidance is not hindered.LikeFurthermore, the ECU 13 does not change the assist force F obtained in step 203 (step211).
[0063]
Note that the steering angular velocity θ_m'Is the steering angle θ_mCan be obtained by differentiating. Further, the steering angular velocity θ_mInstead of ', it is possible to determine whether or not rapid steering is being performed based on whether or not the steering torque T is greater than a predetermined value.
[0064]
  Further, when it is determined that the absolute value of the difference between the actual steering angle θm and the target steering angle θ is less than the predetermined angle θ1 (YES in step 207), the required steering angle is sufficiently small and stable. Since it can be considered that the vehicle is almost running, the ECU 13 does not change the assist force F obtained in step 203 (step211).
[0065]
That is, when traveling at a certain speed or more, when a sharp steering is performed, and when the steering angle is sufficiently small, the normal assist force F is set and the assist force F is changed more than necessary. I do not do it.
[0066]
The present invention is not limited to the above embodiments, and can be variously modified. For example, the steering device uses an electric motor, but may use a hydraulic pressure. When hydraulic pressure is used, the assist force for steering can be controlled by adjusting the hydraulic pressure.
[0067]
In addition, the motor rotation angle_mHowever, the rotation angle of the steering shaft may be detected by an encoder, or the position of a part that is displaced as the steering wheel is steered may be detected by a potentiometer.
[0068]
In the route guidance device, the vehicle speed may be obtained based on the displacement of the position of the vehicle on the road map.
[0069]
The turning radius of the road ahead of the vehicle may be obtained from the shape of the road on the imaging screen by imaging the road with an imaging device.
[0070]
In addition to using route guidance devices, vehicle information and communication systems, and artificial satellites, weather and temperature information can be extracted from received information from various broadcasting stations, and temperature sensors, sunshine sensors, The weather and temperature may be determined with reference to the detection output of a raindrop sensor or the like.
[0071]
【The invention's effect】
  As described above, according to the present invention, the target steering angleofCompared to the assist force applied to the steering in the direction, the assist force applied to the steering in the direction opposite to the target steering angle is small.ofNecessary for steering in the directionoperationCompared to the force, the operation force required for steering in the direction opposite to the target steering angle increases, and steering in the opposite direction becomes difficult. In contrast, the target steering angleDirectionThe operating force required for steering to the target is the target steering angleofDirection andIsReverse directionWhatRequired for steeringoperationTarget steering angle because it is smaller than forceDirectionCan be easily steered. Therefore, the driver can change the actual steering angle to the target steering angle by a simple operation of steering to the side where the operation force is small.
[0072]
According to one embodiment, since the assist force is increased or decreased by controlling the electric motor, the control can be easily performed.
[0073]
  According to one embodiment, the target steering angle increases as the steering angle of the vehicle deviates from the target steering angle.ofNecessary for steering in the directionoperationAs compared with the force, the operation force required for steering in the direction opposite to the target steering angle is increased. For this reason, the driver can recognize that the actual steering angle is greatly deviated from the target steering angle.
[0074]
According to one embodiment, when emergency avoidance is performed, rapid steering is performed and the steering angular velocity and the steering torque increase. The control is stopped, and the assist force is not reduced even when steering is performed in the direction opposite to the target steering angle so that steering for emergency avoidance is not hindered.
[0075]
According to one embodiment, when the vehicle is traveling at a predetermined speed or more, it is determined that the vehicle is traveling stably, and the assist force is not reduced even when steering is performed in a direction opposite to the target steering angle. By simplifying the control.
[0076]
According to one embodiment, when the steering angle is small, it can be regarded as a situation in which stable running is almost performed, so the assist force is not reduced even when steering in the direction opposite to the target steering angle, Simplify control.
[Brief description of the drawings]
FIG. 1 is a schematic configuration diagram showing a first embodiment of a power steering control device of the present invention.
FIG. 2 is a flowchart showing a control process in the first embodiment.
FIG. 3 is a graph showing a normal characteristic curve of assist force F with respect to steering torque T in the first embodiment.
FIG. 4 is a diagram used for explaining a function expressed from a steering coefficient of a vehicle, a wheel base, and a radius of a road.
FIG. 5 is a graph showing another characteristic curve of the assist force F with respect to the steering torque T in the first embodiment.
FIG. 6 is a graph showing another characteristic curve of the assist force F with respect to the steering torque T in the first embodiment.
FIG. 7 is a flowchart showing a control process in the second embodiment of the power steering control device of the present invention;
FIG. 8 is a graph showing a characteristic curve of assist force F with respect to steering torque T in the second embodiment.
FIG. 9 is a graph showing another characteristic curve of the assist force F with respect to the steering torque T in the second embodiment.
[Explanation of symbols]
1 Steering device
10 Steering shaft
11 Steering wheel
12 Torque sensor
13 Electronic control unit (ECU)
14 Motor
20 Steering wheel steering mechanism
21 Vehicle speed sensor
22 Route guidance device
23 Vehicle information collection device

Claims (4)

Assist means for providing assist force to the steering of the vehicle;
Traveling route information output means for outputting information of the traveling route of the vehicle;
Target steering angle calculation means for obtaining a target steering angle of the vehicle based on information on the travel route from the travel route information output means;
Compared to the assist force given to the steering in the direction of the target steering angle obtained by the target steering angle calculation means, the assist force given to the steering in the direction opposite to the target steering angle is small. and means for controlling the pre-Symbol assist unit so that the actual steering angle and the larger the difference between the target steering angle, the assist force and the target given for steering to the target steering angle of the vehicle First control means for increasing the difference in assist force applied to steering in a direction opposite to the steering angle ;
Regardless of whether the steering direction of the vehicle is the direction of the target steering angle determined by the target steering angle calculation means or the direction opposite to the target steering angle, the steering of the vehicle Second control means for controlling the assist means so that an assist force is applied thereto,
When the steering angular velocity or steering torque is below a predetermined value, the control of the assist means by the first control means is selected, and when the steering angular speed or steering torque is greater than the predetermined value, the control of the assist means by the second control means is selected. A power steering control device comprising first assist control mode selection means.   The power steering control device according to claim 1, wherein the assist means applies assist force by an electric motor. When the vehicle speed is higher than a predetermined speed, the control of the assist means by the second control means is selected, and when the vehicle speed is equal to or lower than the predetermined speed, the control of the assist means by the first assist control mode selection means is selected. The power steering control device according to claim 1, further comprising second assist control mode selection means for selecting control of the assist means. When the difference between the actual steering angle of the vehicle and the target steering angle is less than a predetermined value, the control of the assist means by the second control means is selected, and the difference between the actual steering angle of the vehicle and the target steering angle is predetermined. the third assist control mode selecting means for selecting a control of the assist unit as when the above values according to the selection of the control of the assist unit according to the first assist control mode selection means, according to claim 1 or 2, further provided with Power steering control device.

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