JP3882894B2 - Steering reaction force control device - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a steering reaction force control device that controls a steering reaction force against a driver's steering.
[0002]
[Related background]
In a general power steering apparatus that does not have a steering reaction force control function, the steering reaction force is naturally determined according to tire characteristics, suspension type, power steering assist characteristics, and the like. These tire characteristics, suspension type, assist characteristics, etc. are factors that greatly affect the vehicle's driving characteristics (for example, maneuverability and stability). The optimal setting for the reaction force is not always made.
[0003]
For example, the steering reaction force is influenced by the front wheel lateral force generated when the vehicle turns and the self-aligning torque due to the suspension, and the vehicle front axle slip angle (the angle of the vehicle body with respect to the vehicle turning direction) and the front wheel slip angle (the vehicle turning angle). In the region where the angle of the front wheel with respect to the direction is large, it sharply decreases. However, such characteristics tend to cause excessive steering of the driver near the turning limit. Rather, in order to promote the driver's steering wheel return and stabilize the vehicle behavior, there is a characteristic that increases the steering reaction force. Desirably, the conventional power steering apparatus cannot satisfy this demand.
[0004]
[Problems to be solved by the invention]
As a countermeasure, a technique for controlling the steering reaction force based on the vehicle body slip angle has been proposed. As is well known, the vehicle body slip angle is generated with a delay with respect to the steering of the steered wheels. In addition, there is a possibility that a delay in response occurs and the driver feels uncomfortable.
[0005]
On the other hand, in a vehicle equipped with a driving simulator or a power steering that does not mechanically connect the steering wheel and the steering wheel directly and turns the steering wheel by an electric motor or the like according to the detected steering angle, the steering reaction force accompanying the steering is Since it is not transmitted to the steering wheel, it is necessary to intentionally generate a steering reaction force. For this reason, for example, in Noto 3147653, the basic steering reaction force is calculated in consideration of the self-aligning torque of the steered wheels, and the steering reaction force is weighted according to the slip angle of the steered wheels, The obtained steering reaction force is applied to the steering wheel.
[0006]
However, since the purpose of this technique is to apply a steering reaction force to a steering wheel to which no steering reaction force is transmitted, the goal is to accurately simulate the steering reaction force generated by actual steering. Yes. That is, the purpose is different from the case where the steering reaction force is positively controlled to stabilize the vehicle behavior as described above. Therefore, when the technology is applied, it corresponds to the slip angle of the steering wheel. As a result of weighting, control is performed in a direction in which the steering reaction force is increased as the slip angle is smaller, and the steering reaction force is reduced in the region near the turning limit, which tends to cause disturbance of the vehicle behavior. Resulting in.
[0007]
An object of the present invention is to provide a steering reaction force control device capable of appropriately controlling a steering reaction force without causing a sense of incongruity due to a response delay and realizing stabilization of vehicle behavior.
[0008]
[Means for Solving the Problems]
In order to achieve the above object, according to the first aspect of the present invention, there is provided a steering means connected to a steering wheel of a vehicle via a mechanical element and capable of turning the steering wheel, and an actuator capable of applying an operating force to the steering means. , A skid angle detecting means for detecting a skid angle with respect to the road surface of the steered wheel, Based on the sideslip angle detected by the sideslip angle detecting means, the steering reaction force generated in the steering means due to the lateral force of the steering wheel during turning, and the steering means due to the self-aligning torque of the suspension are generated. Steering additional torque calculating means for calculating a steering additional torque for compensating the steering reaction force; Steering with side slip angle The actuator is controlled based on the additional torque to generate a steering reaction force in the steering means that is approximately proportional to the side slip angle. Control means.
[0009]
The steering reaction force at the time of turning of the vehicle has a characteristic that it decreases in a region where the side slip angle of the steered wheel is large due to the influence of the lateral force acting on the steered wheel and the self-aligning torque by the suspension. The steering additional torque for compensating the steering reaction force caused by these lateral forces and the steering reaction force caused by the self-aligning torque is calculated by the steering additional torque calculation means, and the actuator is operated by the control means based on the steering additional torque. Be controlled. As a result, the steering means In the direction in which the side slip angle occurs, that is, in the steering neutral direction Steering reaction force is added, as a result Reduction of steering reaction force in the region where the side slip angle is large is suppressed. Therefore, a steering reaction force approximately proportional to the side slip angle is generated in the steering means. The Therefore, in the region near the turning limit where the side slip angle is large, the driver's excessive steering is suppressed, and the driver's steering wheel return is positively promoted, so that the vehicle behavior is stabilized. Since the side slip angle of the steered wheels occurs almost simultaneously with the steering of the steered wheels for turning the vehicle, the steering reaction force control described above can be performed without giving the driver a sense of incongruity due to response delay.
[0010]
In the invention of claim 2, Steering additional torque calculation If the skid angle is less than or equal to a predetermined value, Calculate approximately 0 as steering additional torque Configured to do. Therefore, in the region where the side slip angle is less than the predetermined value and the trouble due to the decrease in the steering reaction force does not occur, Since approximately 0 is calculated as the steering additional torque, The addition of the steering reaction force by the control of the actuator is stopped, thereby avoiding unnecessary driving loss of the actuator.
[0011]
Furthermore, the invention according to claim 3 further includes a movement state detection means for detecting the movement state of the vehicle, and the control means has a steering angle of the steered wheel when the detection value of the movement state detection means is a predetermined value or less. The actuator is controlled to be small.
Therefore, when the vehicle motion state, for example, the yaw rate or the lateral acceleration is equal to or less than a predetermined value, it can be regarded not as a result of the driver's active steering but as a disturbance of the vehicle behavior due to a disturbance such as a cross wind. At this time, the vehicle is forcibly steered by the influence of the caster trail of the suspension in the direction of action of disturbances such as crosswinds and cross gradients (downward when crosswinds and down when crosswinds). Therefore, in the control of the invention of claim 1, the side slip angle is generated in a direction opposite to that during turning by normal steering, and a steering reaction force is added in the direction in which the side slip angle is generated. Will be encouraged. In such a case, since the control of the actuator is switched so as to reduce the steering angle of the steered wheels, the straight traveling performance of the vehicle is maintained as a result, and adverse effects due to disturbance are prevented in advance.
[0012]
On the other hand, the invention according to claim 4 further includes operation state detection means for detecting the operation state of the steering means by the occupant, and the control means controls the steering wheel when a skid angle occurs regardless of the occupant's operation. The actuator is configured to be controlled so that the angle becomes small.
Therefore, when the operation state of the steering means, for example, the steering angle or the steering torque is less than a predetermined value, it can be regarded as a disturbance of the vehicle behavior due to the side wind or the side slope of the road surface, not the driver's active steering. And since the steering wheel is forcibly steered to the leeward direction or the lower gradient side under the influence of the caster trail of the suspension at this time, the side slip angle is generated in the opposite direction to the turning by the normal steering, In the control according to the first aspect of the present invention in which the steering reaction force is added in the direction in which the side slip angle is generated, steering in the leeward direction or the lower gradient side is promoted. In such a case, since the control of the actuator is switched so as to reduce the steering angle of the steered wheels, the straight traveling performance of the vehicle is maintained as a result, and adverse effects due to the lateral gradient are prevented in advance.
[0013]
In the invention of claim 5, the steering means is an electric power steering that adds assisting force to the occupant's operation by an electric motor provided as an actuator, and the control means is a friction on the handle return side of the electric power steering. The electric motor is controlled so as to cancel out the above.
Accordingly, since the friction on the steering wheel return side of the electric power steering is canceled, when the driver stops the steering, the steering wheel smoothly returns to the neutral position, and the operational feeling is improved.
[0014]
DETAILED DESCRIPTION OF THE INVENTION
[First Embodiment]
Hereinafter, a first embodiment in which the present invention is embodied in a steering reaction force control device applied to an electric power steering device will be described.
FIG. 1 is an overall configuration diagram showing a steering reaction force control apparatus according to the present embodiment. As shown in this figure, the steering wheel 1 is connected to a gear box 3 via a steering shaft 2, and the gear box 3 is connected to front wheels 5 (steering wheels) of the vehicle via left and right tie rods 4. When the steering wheel 1 is rotated by the driver, the rotation is converted into a left and right linear motion by the gear box 3, and the steering wheel 5 is turned through the tie rod 4. In this embodiment, the steering means is constituted by the steering wheel 1, the steering shaft 2, the gear box 3, and the tie rod 4. An electric motor (actuator) 6 is mounted on the gear box 3, and the rotation of the electric motor 6 is input to the gear box 3 to assist steering by the driver.
[0015]
An ECU (electronic control unit) 11 as a control means for executing overall control of the power steering apparatus is installed in the vehicle interior, and includes an input / output device (not shown), a storage device (ROM, RAM, etc.), a central processing unit ( CPU), a timer counter, and the like. On the input side of the ECU 11, a torque sensor 12 that detects the steering torque Tsw applied to the steering wheel 1 by the driver, a steering angle sensor 13 that detects the steering angle δsw by the driver, and a vehicle speed sensor 14 that detects the vehicle speed V. Various sensors such as a yaw rate sensor 15 for detecting the yaw rate γ of the vehicle and a lateral acceleration sensor 16 for detecting the lateral acceleration ay of the vehicle are connected, and devices such as the electric motor 6 are connected to the output side of the ECU 11. Has been.
[0016]
FIG. 2 is a flowchart showing a steering additional torque calculation routine executed by the ECU 11. The ECU 11 executes this routine at a predetermined control interval, and first inputs detection information from the sensors in step S2. Next, the slip angle βf of the front wheel 5 is calculated in step S4, and then the steering additional torque Ta is calculated in step S6, and the routine is terminated.
[0017]
FIG. 3 is a block diagram showing a calculation procedure of the steering torque Ts performed by the ECU 11 in accordance with the above routine. Hereinafter, the processing of the ECU 11 will be further described based on this figure.
The steering torque Tsw detected by the torque sensor 12 and the vehicle speed V detected by the vehicle speed sensor 14 are input to the basic assist torque setting unit 21, and the steering torque Tsw and the vehicle speed V according to a map set in advance by the setting unit 21 are obtained. From this, the basic assist torque T0 (specifically, the motor current value) is calculated.
[0018]
On the other hand, the steering angle δsw detected by the steering angle sensor 13 is input to the actual steering angle setting unit 22, and the setting unit 22 calculates the front wheel actual steering angle δf according to the following equation (1). Here, N is a steering gear ratio.
δf = δsw / N ……… (1)
Further, the vehicle speed V detected by the vehicle speed sensor 14, the yaw rate γ detected by the yaw rate sensor 15, and the lateral acceleration ay detected by the lateral acceleration sensor 16 are input to the vehicle body front shaft slip angle setting unit 23, and the setting unit 23 Thus, the vehicle body front shaft slip angle βfa is calculated according to the following equation (2). Here, Lf is the distance between the center of gravity of the vehicle and the front shaft.
[0019]
βfa = ∫γdt−∫ (ay / V) dt + γLf / V (2)
The vehicle body front shaft slip angle βfa is generally calculated as a yaw angular velocity integration method, but other calculation methods may be applied. For example, a vehicle model method is used in which the relationship between the vehicle speed V and the steering angle δsw and the vehicle body front shaft slip angle βfa is modeled by an actual vehicle test, and the vehicle body front shaft slip angle βfa is calculated from the detected vehicle speed V and the steering angle δsw. Alternatively, the vehicle body front wheel slip angle βfa may be directly detected using an optical skid measuring device.
[0020]
FIG. 4 shows a situation of occurrence of a slip angle when the vehicle turns. During turning of the vehicle, the turning direction on the front axis of the vehicle with respect to the actual front wheel steering angle δf given by the driver, that is, the front axis of the vehicle body The slip angle βfa is shifted, and the front wheel slip angle βf is generated.
In the subtraction processing unit 24 to which the front wheel actual steering angle δf and the vehicle body front shaft slip angle βfa are input, the front wheel slip angle βf is calculated according to the following equation (3).
[0021]
βf ＝ δf−βfa ……… (3)
The calculated front wheel slip angle βf is input to the steering additional torque setting unit 25, and the setting unit 25 calculates the steering additional torque Ta (motor current value) based on the map shown in FIG. As shown in the figure, the steering additional torque Ta is suppressed to 0 in a small region where the front wheel slip angle βf is smaller than a predetermined value βf0 (absolute value), and when the front wheel slip angle βf exceeds the predetermined value βf0, the front wheel slip angle βf It is set so as to increase rapidly with the increase of. Note that the specific value of βf0 is preferably about 5 to 7 deg.
[0022]
The steering additional torque Ta and the basic assist torque T0 are input to the addition processing unit 26, and the setting unit 26 calculates the steering torque Ts (motor current value) according to the following equation (4).
Ts = T0 + Ta (4)
The electric motor 6 is driven and controlled by the current driver 27 based on the obtained steering torque Ts, thereby assisting the steering by the driver.
[0023]
As described above, in the steering reaction force control device of the present embodiment, the steering additional torque Ta corresponding to the front wheel slip angle βf is added to the basic assist torque T0 to obtain the steering torque Ts of the power steering device. The operation of the steering reaction force control device will be described.
FIG. 6 shows the generation state of the front wheel lateral force Fy and the self-aligning torque Tsa when the vehicle is turning, FIG. 7 shows the characteristics of the steering reaction force Tfy generated by the front wheel lateral force Fy, and FIG. 8 shows the self-aligning torque. The characteristic of the steering reaction force Tsat generated by Tsa is shown, and FIG. 9 shows the characteristic obtained by adding the steering reaction forces Tfy and Tsat.
[0024]
The upper stage in FIG. 6 is a plan view of the front wheel 5, and the lower stage is a side view of the front wheel 5. As shown in this figure, the lateral force Fy accompanying the turning acts on the front wheel 5 while the vehicle is turning. A self-aligning torque Tsa is generated by the front wheel suspension. Since the front wheel lateral force Fy is converted into torque by the suspension castor trail ξ, the steering reaction force Tfy generated at the steering position by the front wheel lateral force Fy is expressed by the following equation (5), where N is the steering gear ratio. The
[0025]
Tfy = Fy (βf) × ξ × 1 / N (5)
The front wheel lateral force Fy correlates with the front wheel slip angle βf, and the obtained steering reaction force Tfy has a characteristic of gradually increasing as the front wheel slip angle βf increases as shown in FIG.
Similarly, the steering reaction force Tsat generated at the steering position by the self-aligning torque Tsa is expressed by the following equation (6).
[0026]
Tsat = Tsa (βf) × 1 / N ……… (6)
The self-aligning torque Tsa also correlates with the front wheel slip angle βf, and the obtained steering reaction force Tsat has a characteristic of rapidly decreasing after rapidly increasing with an increase in the front wheel slip angle βf, as shown in FIG. As a result, a steering reaction force Tfy + Tsat (in other words, a steering torque required for steering operation), which is the sum of these steering reaction forces Tfy and Tsat, acts on the steering wheel 1, and the steering reaction force Tfy + Tsat is as shown in FIG. Then, it increases rapidly in proportion to the increase in the front wheel slip angle βf and then decreases rapidly.
[0027]
Since the steering additional torque Ta corresponding to the front wheel slip angle βf is added to the steering torque Ts as described above, the value obtained by adding the steering additional torque Ta to the steering reaction force Tfy + Tsat as shown in FIG. The actual steering torque Ts acts on the steering wheel 1. That is, the added steering additional torque Ta acts in the neutral direction where the front wheel slip angle βf is generated to increase the steering reaction force, and as a result, the steering increases in proportion to the increase in the front wheel slip angle βf. Reaction force characteristics can be obtained.
[0028]
Therefore, even in the region near the turning limit where the front wheel slip angle βf is large, the steering reaction force does not decrease rapidly but increases with the increase in the front wheel slip angle βf, and the driver excessively steers near the turning limit. In addition, it is possible to positively prompt the driver to return the steering wheel, and to stabilize the vehicle behavior as a result.
The front wheel slip angle βf for setting the steering additional torque Ta is generated almost simultaneously with the front wheel actual rudder angle δf without being delayed with respect to the front wheel actual rudder angle δf like the vehicle body front shaft slip angle βfa. In the region near the turning limit where the front wheel slip angle βf is large, the steering reaction force is immediately increased, and the above-described stabilization of the vehicle behavior can be realized without giving the driver a sense of incongruity due to response delay.
[0029]
Further, the characteristics of the steering reaction force Tfy + Tsat shown in FIG. 9 vary depending on the type of tire, the wear state, the suspension type, the vehicle weight, the loaded weight, etc., but these factors are corrected by the correction based on the steering additional torque Ta. The vehicle behavior can be stabilized as described above without being affected. For example, even a lightweight vehicle in which the steering reaction force tends to be insufficient when traveling at high speed, a sufficient steering reaction force can be obtained and stabilization can be achieved.
[0030]
On the other hand, as is apparent from the characteristics of FIG. 9, in a region where the front wheel slip angle βf is small, a steering reaction force Tfy + Tsat that is substantially proportional to the front wheel slip angle βf is obtained. In the case of βf0 or less), the steering additional torque Ta is suppressed to 0 because it is not necessary to correct the steering reaction force. Therefore, there is an advantage that power loss due to useless motor driving can be avoided.
[0031]
In this embodiment, in order to make the steering reaction force characteristic with respect to the front wheel slip angle βf linear, control is performed so that the steering additional torque Ta shown in FIG. 5 is added to the characteristic of Tfy + Tsat shown in FIG. However, the present invention is not limited to this, and for example, a steering additional torque Ta having a linear characteristic with respect to the front wheel slip angle βf as shown in FIG. 15 may be added. Also in this case, the steering reaction force loss near the turning limit of the vehicle is suppressed, and the vehicle behavior can be stabilized by suppressing excessive steering of the driver.
[0032]
[Second Embodiment]
Next, a second embodiment in which the present invention is embodied in another steering reaction force control device will be described. The steering reaction force control apparatus of the present embodiment is different from that of the first embodiment in that the setting process of the steering additional torque Ta is switched when a disturbance such as a cross wind of the vehicle acts. Therefore, the description of a common structure is abbreviate | omitted and it demonstrates focusing on a different point.
[0033]
FIG. 11 is a flowchart showing a steering additional torque calculation routine executed by the ECU 11. First, in step S12, detection information from the yaw rate sensor 15 (motion state detecting means) is read, and in step S14, it is determined whether or not the absolute value of yaw rate γ is less than a predetermined value γth. The purpose of the processing is to determine whether or not the vehicle is subjected to disturbance such as crosswind. In other words, yaw rate γ is generated even when the behavior of the vehicle is disturbed due to disturbance, but the value is small compared to the case of the driver's active steering, so it depends on any factor based on yaw rate γ. It is discriminating whether it is a thing. For example, 0.05 rad / sec (2.9 deg / sec) is set as the predetermined value γth.
[0034]
When the determination in step S14 is NO (ie, negative), that is, when it is estimated that the yaw rate γ is large and the driver has made a turn by steering, the sensor detection information is input in step S2 as in the first embodiment. After executing the calculation process of the front wheel side slip angle βf in step S4 and the calculation process of the steering additional torque Ta based on the front wheel slip angle βf in step S6, the routine is ended. Therefore, the steering reaction force is increased in the region near the turning limit where the front wheel slip angle βf is large, and the vehicle behavior is stabilized.
[0035]
When the determination in step S14 is YES (affirmative), that is, when it is estimated that the yaw rate γ is small and due to disturbance, the process proceeds to step S16, and the steering additional torque Ta corresponding to the yaw rate γ is determined according to a map (not shown). After the calculation, the routine ends. At this time, the steering additional torque Ta is set to increase with an increase in, for example, the yaw rate γ. As a result, the steering reaction force (steering torque Ts) is strengthened as the vehicle behavior is disturbed by the disturbance, and the straightness of the vehicle is maintained. It is.
[0036]
Here, when a disturbance such as a cross wind acts on the vehicle, the front wheel 5 is forcibly steered in the leeward direction under the influence of the caster rail ξ. Therefore, the front wheel slip angle βf at this time is determined by the normal steering shown in FIG. It occurs in the opposite direction to the turning. Therefore, when the processes of steps S2 to S6 are performed, the steering additional torque Ta is set as a reverse polarity from the map of FIG. 5, and as a result, the steering torque Ta acts to promote steering in the leeward direction. It will be.
[0037]
As described above, in the present embodiment, in such a case, the process is switched from the process of steps S2 to S16 to the process of step S16, and the steering torque Ts is controlled in a direction to suppress the yaw rate γ. In addition to the effects, there is an advantage that adverse effects due to disturbances such as crosswinds can be prevented.
In this embodiment, the steering reaction force control is switched based on the yaw rate γ. However, for example, the lateral acceleration ay also changes as the vehicle behavior is disturbed. The lateral acceleration ay detected by the means) may be used. Specifically, the yaw rate γ in the flowchart is replaced with the lateral acceleration ay, and the predetermined value γth is changed to a predetermined value ayth, for example, 0.5 m / sec. ² (0.05G) may be substituted.
[0038]
In the present embodiment, as described above, the steering additional torque Ta is not added by the front wheel slip angle βf when the yaw rate γ and the lateral acceleration ay are within a predetermined value or less. For this reason, when the characteristic that the steering additional torque Ta increases linearly with respect to the front wheel slip angle βf as shown in FIG. 15 in the first embodiment in a range where the yaw rate γ and the lateral acceleration ay are equal to or larger than a predetermined value, As shown in FIG. 16, in a region where the front wheel slip angle βf is equal to or less than a predetermined value βf1 (a value corresponding to a predetermined value of yaw rate γ or lateral acceleration ay, for example, 0.5 deg), the steering additional torque Ta is 0 and the front wheel The map may be such that the steering additional torque Ta increases linearly in the region where the slip angle βf exceeds the predetermined value βf1.
[0039]
[Third Embodiment]
Next, a third embodiment in which the present invention is embodied in another steering reaction force control device will be described. The steering reaction force control apparatus of the present embodiment is different from that of the second embodiment in that the setting process of the steering additional torque Ta is switched when the vehicle is traveling on a laterally inclined road. Therefore, the description of a common structure is abbreviate | omitted and it demonstrates focusing on a different point.
[0040]
FIG. 12 is a flowchart showing a steering additional torque calculation routine executed by the ECU 11. In step S22, detection information from the steering angle sensor 13 (operation state detecting means) is read, and in step S24, the absolute value of the steering angle δsw by the driver is read. Is less than a predetermined value δswth. The purpose of the processing is to determine whether or not the vehicle is traveling on a road surface having a lateral slope. In other words, since the vehicle weight acts laterally on the road surface with the lateral slope, the front wheel 5 is forcibly steered downward by the influence of the caster rail ξ as in the case of the disturbance of the second embodiment. A steering angle δsw is generated. Since the steering angle δsw at this time is smaller than that by the driver's active steering, it is determined which factor is based on the steering angle δsw. For example, 0.2 rad (11 deg) is set as the predetermined value Δswth.
[0041]
When the determination in step S24 is NO and it is estimated that the vehicle is turning by steering, the processes in steps S2 to S6 are executed as in the second embodiment. Therefore, the steering reaction force is increased in the region near the turning limit where the front wheel slip angle βf is large, and the vehicle behavior is stabilized.
When the determination in step S24 is YES, that is, when it is estimated that the steering angle δsw is small and the vehicle is traveling on a road surface having a lateral slope, the process proceeds to step S26, and steering addition according to the steering angle δsw is performed according to a map (not shown). After calculating the torque Ta, the routine is terminated. The steering additional torque Ta at this time is set to increase with an increase in the steering angle δsw, for example, and as a result, the steering reaction force (steering torque Ts) is strengthened as the vehicle behavior is disturbed by the lateral gradient, and the straightness of the vehicle is improved. Kept.
[0042]
Here, when traveling on a road surface with a lateral slope, a front wheel slip angle βf is generated in a direction opposite to that when turning by normal steering, as in the disturbance of the second embodiment. Steering torque Ta acts so as to promote the downward steering, further disturbing the vehicle behavior. In this embodiment, since the steering torque Ts is controlled in such a case as to suppress the steering angle δsw in step S26, there is an advantage that adverse effects due to the lateral gradient can be prevented in advance.
[0043]
In the present embodiment, the steering reaction force control is switched based on the steering angle δsw. However, for example, the steering torque Tsw detected by the torque sensor 12 (operation state detecting means) may be used instead of the steering angle δsw. Good. That is, when the steering torque Tsw is large, it is regarded as a driver's steering, and when the steering torque Tsw is small, it is regarded as a lateral gradient, and the process may be switched accordingly. Further, the greater the influence of the lateral gradient, the greater the driver's steering torque Tsw in order to keep going straight. Therefore, if the steering additional torque Ta is set to increase as the steering torque Tsw increases, the straightness of the vehicle is maintained. be able to. Therefore, specifically, the steering angle δsw in the flowchart is replaced with the steering torque Tsw, and the predetermined value δswth is replaced with a predetermined value Tswth, for example, 0.5 Nm.
[0044]
Also in the present embodiment, as in the second embodiment, the map shown in FIG. 16 as the map of the steering impossible torque Ta with respect to the front wheel slip angle βf may be used.
[Fourth Embodiment]
Next, a fourth embodiment in which the present invention is embodied in another steering reaction force control device will be described. The steering reaction force control device of this embodiment is different from that of the first embodiment in that a steering additional torque Tb for canceling the friction of the electric power steering device is taken into consideration. Therefore, the description of a common structure is abbreviate | omitted and it demonstrates focusing on a different point.
[0045]
The ECU 11 executes the routine of FIG. 2 as in the first embodiment, and in step S6, in addition to the steering additional torque Ta, the steering additional torque Tb having a substantially constant value is set on the steering wheel return side based on the map of FIG. . This setting process is performed by the steering additional torque setting unit 25 in FIG. 3, and the set steering additional torques Ta and Tb are added to the basic assist torque T0 by the addition processing unit 26 to calculate the steering torque Ts.
[0046]
Therefore, as in the first embodiment, the steering reaction force is controlled so as to increase in the vicinity of the turning limit, so that the vehicle behavior is stabilized. In addition, a constant steering additional torque Tb acts on the steering wheel return side. Will do. As is well known, since the electric power steering device always generates a friction torque Tfr in the direction opposite to the rotational direction as shown in FIG. 14 due to the friction of the speed reduction mechanism (particularly the worm type) of the electric motor 6, Only with the steering reaction force Tsat due to the lining torque Tsa, the steering wheel returns to the neutral position is poor. In the present embodiment, the friction torque Tfr on the steering wheel return side is offset by the steering additional torque Tb, so that when the driver stops the steering, the steering wheel 1 smoothly returns to the neutral position, greatly increasing the operational feeling. There is an advantage that it can be improved.
[0047]
This is the end of the description of the embodiment, but the aspect of the present invention is not limited to this embodiment. For example, in the above embodiment, the steering reaction force control device is applied to the electric power steering device, but may be applied to a hydraulic power steering device. Specifically, the electric motor 6 is installed in the power steering device, and the electric motor 6 is driven and controlled by the current driver 27 based on the steering additional torque Ta set by the steering additional torque setting unit 25 in FIG. Thus, the steering torque (corresponding to the basic assist torque T0) by the hydraulic pressure on the power steering device side may be corrected.
[0048]
【The invention's effect】
As described above, according to the steering reaction force control apparatus of the first aspect, the steering reaction force can be appropriately controlled without causing a sense of incongruity due to a response delay, and the stabilization of the vehicle behavior can be realized.
Moreover, according to the steering reaction force control device of claim 2, in addition to the invention of claim 1, useless driving loss of the actuator can be avoided in advance.
[0049]
Furthermore, according to the steering reaction force control apparatus of claim 3, in addition to the invention of claim 1, adverse effects due to disturbances such as cross winds can be prevented in advance.
On the other hand, according to the steering reaction force control apparatus of the fourth aspect, in addition to the invention of the first aspect, it is possible to prevent adverse effects due to the lateral gradient.
Further, according to the steering reaction force control device of the fifth aspect, in addition to the first to fourth aspects of the invention, the friction of the electric power steering can be offset and the operational feeling can be greatly improved.
[Brief description of the drawings]
FIG. 1 is an overall configuration diagram showing a steering reaction force control apparatus according to a first embodiment.
FIG. 2 is a flowchart showing a steering additional torque calculation routine executed by the ECU of the first embodiment.
FIG. 3 is a block diagram showing a procedure for calculating a steering torque Ts.
FIG. 4 is a diagram showing a state of occurrence of a slip angle when the vehicle is turning.
FIG. 5 is a diagram showing a map for setting a steering additional torque Ta.
FIG. 6 is a diagram showing a state of generation of front wheel lateral force Fy and self-aligning torque Tsa when the vehicle is turning.
FIG. 7 is a characteristic diagram of a steering reaction force Tfy generated by a front wheel lateral force Fy.
FIG. 8 is a characteristic diagram of a steering reaction force Tsat generated by a self-aligning torque Tsa.
FIG. 9 is a characteristic diagram in which steering reaction forces Tfy and Tsat are added.
FIG. 10 is a characteristic diagram of steering torque Ts.
FIG. 11 is a flowchart showing a steering additional torque calculation routine executed by the ECU of the second embodiment.
FIG. 12 is a flowchart showing a steering additional torque calculation routine executed by the ECU of the third embodiment.
FIG. 13 is a diagram showing a map for setting a steering additional torque Tb according to the fourth embodiment.
FIG. 14 is a characteristic diagram showing a generation state of friction torque Tfr in the electric power steering apparatus.
FIG. 15 is a diagram showing another example of a map for setting the steering additional torque Ta according to the first embodiment.
FIG. 16 is a diagram showing another example of a map for setting the steering additional torque Ta according to the second embodiment.
[Explanation of symbols]
1 Steering wheel (steering means)
2 Steering shaft (steering means)
3 Gearbox (steering means)
4 Tie rod (steering means)
5 Front wheels (steering wheels)
6 Electric motor (actuator)
11 ECU (control means)
12 Torque sensor (operation state detection means)
13 Steering angle sensor (operation state detection means)
15 Yaw rate sensor (motion state detection means)
16 Lateral acceleration sensor (motion state detection means)

Claims (5)

Steering means coupled to a steering wheel of a vehicle via a mechanical element and capable of turning the steering wheel;
An actuator capable of applying an operating force to the steering means;
A skid angle detecting means for detecting a skid angle of the steered wheel with respect to the road surface;
Based on the side slip angle detected by the side slip angle detecting means, the steering reaction force generated in the steering means due to the lateral force of the steering wheel during turning, and the steering due to the self-aligning torque of the suspension. Steering additional torque calculating means for calculating a steering additional torque for compensating the steering reaction force generated in the means;
Steering reaction, characterized in that a said side slip angle control means for substantially Ru is generated proportional to the steering reaction force to the steering means to control the actuator based on the steering additional torque due to the occurrence of the slip angle Force control device. 2. The steering reaction force control device according to claim 1, wherein the steering additional torque calculation unit calculates substantially zero as the steering additional torque when the side slip angle is equal to or less than a predetermined value. And further comprising a motion state detection means for detecting the motion state of the vehicle,
2. The steering reaction according to claim 1, wherein the control unit controls the actuator so that a steering angle of the steered wheel becomes small when a detection value of the motion state detection unit is a predetermined value or less. Force control device. An operation state detection unit for detecting an operation state of the steering unit by a passenger;
2. The steering reaction according to claim 1, wherein the control unit controls the actuator so that a steering angle of the steered wheel is reduced when the side slip angle is generated regardless of an operation of the occupant. Force control device. The steering means is an electric power steering that adds assisting force to an occupant's operation by an electric motor provided as the actuator.
The steering reaction force control device according to any one of claims 1 to 4, wherein the control means controls the electric motor so as to cancel the friction on the steering wheel return side of the electric power steering.

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