Steering control device, electric power steering device, and vehicle

Abstract

This steering control device comprises: a normal steering control part that controls a torque to be applied to a steering mechanism on the basis of steering of the steering mechanism by a driver; a target steering angular velocity computation part unit that computes a target steering angular velocity on the basis of a signal substantially proportional to a deviation between a steering angle of the steering mechanism and the target steering angle; a steering angular velocity control part that computes a target current on the basis of the target steering angular velocity; a drive part that applies a torque to the steering mechanism on the basis of the target current; a first correction part that multiplies the deviation or the target steering angular velocity by a first correction value in accordance with to the steering torque corresponding to the torque applied to the steering mechanism by the driver; and a second correction part that adds a second correction value in accordance with the steering torque to the deviation or the target steering angular velocity.

Description

Steering control device, electric power steering device, and vehicle

[0001] The present disclosure relates to a steering control device, an electric power steering device, and a vehicle.

[0002] The electric power steering device disclosed in Patent Document 1 performs assist control, which is a function of normal EPS (Electric Power Steering), and steering angle control, which is required for automatic steering in autonomous driving. If a driver intervenes in steering during automatic steering, the device can perform steering intervention compensation according to the steering torque. Specifically, the device compensates for the steering angular velocity command value using a compensation value (compensated steering angular velocity command value) calculated by a steering intervention compensation unit. Specifically, the compensation steering angular velocity command value is added to the steering angular velocity command value. Steering angular velocity control is performed for the compensated steering angular velocity command value. This improves steering angle control and responsiveness during steering intervention.

[0003] Patent No. 6428971

[0004] However, as in Patent Document 1, simply adding a compensation steering angular velocity command value to a steering angular velocity command value poses a problem in that the steering intervention compensation cannot be performed at a sufficient magnitude due to an upper limit on the stability of a feedback loop based on the steering angular velocity control unit and the steering torque feedback of this compensation value, resulting in an increase in the steering torque during intervention.

[0005] Furthermore, the steering angular velocity command value is corrected by a compensation value (compensation steering angular velocity command value) according to the steering torque, but the assist control gradual change gain does not become zero even during automatic steering, and assist control is also executed simultaneously. In reality, steering intervention is realized by the effects of both the compensation steering angular velocity command value and the assist control. In other words, it is considered that the steering intervention compensation amount alone is insufficient. Furthermore, the feeling during steering intervention is the result of both, so the steering feeling is not comfortable, and adjustment is difficult and requires a lot of adjustment work.

[0006] The present disclosure has been made in consideration of the above-mentioned circumstances, and one of its objectives is to provide a steering control device, an electric power steering device, and a vehicle that can provide a light and good steering feeling when the driver intervenes in steering during steering angle control, and that can simply achieve this function.

[0007] The steering control device according to the present disclosure includes a normal steering control unit that controls the torque applied to the steering mechanism based on steering of the steering mechanism by a driver; a target steering angular velocity calculation unit that calculates a target steering angular velocity based on a signal that is approximately proportional to the deviation between the steering angle of the steering mechanism and a target steering angle; a steering angular velocity control unit that calculates a target current based on the target steering angular velocity; a drive unit that applies torque to the steering mechanism based on the target current; a first correction unit that multiplies the deviation or the target steering angular velocity by a first correction value corresponding to a steering torque that corresponds to the torque applied by the driver to the steering mechanism; and a second correction unit that adds a second correction value corresponding to the steering torque to the deviation or the target steering angular velocity.

[0008] The electric power steering device according to the present disclosure includes a steering torque detection unit that detects the steering torque applied by the driver to the steering mechanism, a steering angle detection unit that detects the steering angle of the steering mechanism, and the above-mentioned steering control device that controls a drive unit that applies torque to the steering mechanism based on the detected steering torque and steering angle.

[0009] The vehicle according to the present disclosure includes a vehicle speed detection unit that detects the speed of the vehicle, a controller that outputs a target steering angle that is a target value for the steering angle of the steering mechanism, and the electric power steering device described above that controls the torque applied to the steering mechanism based on the vehicle speed detected by the vehicle speed detection unit and the target steering angle output from the controller.

[0010] According to the present disclosure, the steering feeling when the driver intervenes in steering during steering angle control can be made light and good, and this effect can be realized simply.

[0011] 1 is a block diagram showing the configuration of essential parts of an electric power steering device and a vehicle according to a first embodiment. FIG. 2 is a block diagram showing the configuration of essential parts of a steering control device according to the first embodiment. FIG. 3 is a block diagram showing the internal configuration of a steering angle control unit according to the first embodiment. FIG. 4 is a diagram showing an example of a first correction map according to the first embodiment. FIG. 5 is an example of an override characteristic diagram according to the first embodiment. FIG. 6 is an example of measured data of the override characteristic diagram according to the first embodiment. FIG. 7 is a block diagram showing the internal configuration of a steering angle control unit according to the second embodiment. FIG. 8 is a block diagram showing the internal configuration of a steering angle control unit according to the third embodiment. FIG. 9 is a block diagram showing the internal configuration of a steering angle control unit according to the fourth embodiment. FIG. 10 is a block diagram showing the internal configuration of a steering angle control unit according to the fifth embodiment. FIG. 11 is a diagram showing an example of a second correction map according to the fifth embodiment. FIG. 12 is a block diagram showing the internal configuration of a steering angle control unit according to the sixth embodiment. FIG. 13 is a diagram showing an example of the second correction map according to the sixth embodiment. FIG. 14 is a block diagram showing the internal configuration of a first correction unit according to the seventh embodiment. FIG. 15 is a block diagram showing the internal configuration of a first correction unit according to the eighth embodiment. FIG. 16 is a block diagram showing an example of a first correction map according to the eighth embodiment. FIG. 17 is a block diagram showing the internal configuration of a first correction unit according to the ninth embodiment.

[0012] Hereinafter, a steering control device, an electric power steering device, and a vehicle according to embodiments of the present disclosure will be described in detail with reference to the drawings. In each embodiment, the same or corresponding parts are denoted by the same reference numerals, and a description of overlapping parts will be omitted.

[0013] [Embodiment 1] First, a first embodiment of the present disclosure will be described. <Configuration of electric power steering device and vehicle> Fig. 1 is a block diagram showing an example of the configuration of the main parts of an electric power steering device and a vehicle in embodiment 1. As shown in Fig. 1, a vehicle VE according to this embodiment includes a vehicle speed sensor 8, a host controller 9, and an electric power steering device PS. The electric power steering device PS includes a steering wheel 1, a steering shaft 2, steered wheels 3, a steering angle detection unit (steering angle sensor) 4, a torque sensor 5 (steering torque detection unit), a motor 6, a reduction mechanism 7, and a control unit 11.

[0014] The steering wheel 1 is a so-called handle, and is operated by the driver of the vehicle VE to apply a steering angle to the steered wheels 3 of the vehicle VE. The steering shaft 2 is connected to the steering wheel 1 and rotates in response to the rotation of the steering wheel 1. The steered wheels 3 are provided on both the left and right sides of the vehicle VE and are steered in response to the rotation of the steering shaft 2. The mechanism for steering the steered wheels 3, including the steering wheel 1 and the steering shaft 2, will be referred to as the "steering".

[0015] The steering angle detector 4 is disposed on the steering wheel 1 or the steering shaft 2 and detects the steering angle (steering angle) of the steering shaft. The torque sensor 5 is disposed on the steering shaft 2 and detects the steering torque acting on the steering shaft 2. The steering torque corresponds to the torque applied to the steering wheel 1 by the driver.

[0016] The motor 6 is connected to the steering shaft 2 via a reduction gear mechanism 7 and applies a steering assist torque to the steering shaft 2. A vehicle speed sensor 8 detects the vehicle speed of the vehicle VE. A host controller 9 is a controller having a control function for an advanced driving assistance system such as an autonomous driving system, a lane keep assist system, or an automatic parking system, and outputs a target steering angle, which is a target value for the steering angle of the steering wheel.

[0017] The control unit 11 controls the drive of the motor 6 based on the detection results of the steering angle detection unit 4, the torque sensor 5, and the vehicle speed sensor 8, and the target steering angle output from the host controller 9, to generate a steering assist torque for the steering. Specifically, the control unit 11 calculates a target current for the motor 6 based on the above detection results and the target steering angle, and controls the current for the motor 6 so that the actual current follows the target current. The control unit 11 will be described in detail below.

[0018] 2 is a block diagram showing an example of a configuration of a main part of a steering control device including the control unit 11 in embodiment 1. The configuration including the control unit 11 and the motor 6 is referred to as the steering control device 10. Furthermore, the configuration including the current control unit 26 provided in the control unit 11 and the motor 6 is referred to as the drive unit 25.

[0019] 2, the control unit 11 includes a normal steering control unit 20, a steering angle control unit 21, a switching unit 23, a differentiator 24, and a current control unit 26. The differentiator 24 differentiates the steering angle detected by the steering angle detection unit 4 to calculate a detected steering angular velocity as the steering angular velocity of the steering shaft 2. Note that the steering angle detection unit 4 may be substituted with a motor rotation angle sensor that detects the rotation angle of the motor 6 instead of the steering angle sensor (steering angle sensor), and in that case, the rotation angle of the motor may be integrated to obtain the detected steering angle.

[0020] The normal steering control unit 20 performs normal assist control in the electric power steering device PS and outputs a target assist current. Typically, the normal steering control unit 20 outputs a target assist current corresponding to the steering torque detected by the torque sensor 5, based on an assist map in which a target assist current approximately proportional to the steering torque is stored. The assist map also changes according to the vehicle speed. Therefore, the normal steering control unit 20 outputs the target assist current based on the detection result of the vehicle speed sensor 8, the steering torque detected by the torque sensor 5, and the assist map.

[0021] The normal steering control unit 20 is not limited to the typical assist control described above. For example, the normal steering control unit 20 may include a target steering torque setting unit and a torque feedback calculation unit (not shown), in which the target steering torque setting unit generates a target steering torque based on the steering angle, and the torque feedback calculation unit performs target steering torque control to make the actual steering torque follow the target steering torque. In this case, the target steering torque setting unit sets a target steering torque for the steering using the detected steering angle, vehicle speed, and detected steering angular velocity. Furthermore, the torque feedback calculation unit calculates a target assist current required to make the steering torque follow the target steering torque based on the deviation between the target steering torque and the steering torque.

[0022] The steering angle control unit 21 calculates a target steering angle speed based on the steering angle deviation Δθ, which is the difference between the target steering angle output from the host controller 9 and the detected steering angle detected by the steering angle detection unit 4. The steering angle control unit 21 also calculates and outputs a steering angle control target current in accordance with the deviation between the calculated target steering angle speed and the detected steering angle speed calculated by the differentiator 24. The steering angle control unit 21 also has a configuration that applies a correction to the steering angle control in accordance with the detected steering torque. Details of the steering angle control unit 21 will be described later.

[0023] The switching unit 23 switches between the target assist current output from the normal steering control unit 20 and the steering angle control target current output from the steering angle control unit 21 in accordance with a steering angle control operation signal (not shown). The switching unit 23 receives a steering angle control operation signal generated by the higher-level controller 9 or the steering control device. When the steering angle control operation signal indicates that the steering angle control is in operation, the switching unit 23 outputs the steering angle control target current as the target current. Furthermore, when the steering angle control operation signal indicates that the steering angle control is in a paused state, the switching unit 23 outputs the target assist current as the target current.

[0024] The control unit 11, excluding a portion of the current control unit 26, is implemented by a microcomputer including a CPU (Central Processing Unit) and memory. The memory provided in the microcomputer may include both volatile and non-volatile memory. The current control unit 26 also includes an analog circuit including multiple switching elements such as FETs (Field Effect Transistors). The current control unit 26 generates a command for the analog circuit using the microcomputer so that the actual current output to the motor 6 follows the target current output from the switching unit 23. The current control unit 26 supplies current to the motor 6 from the analog circuit based on the command generated by the microcomputer.

[0025] Next, details of the steering angle control unit 21 will be described with reference to Figures 3 and 4. Figure 3 is a block diagram showing an example of the internal configuration of the steering angle control unit in embodiment 1. As shown in Figure 3, the steering angle control unit 21 includes a subtraction unit 31, a steering angle control gain 32, a steering angle speed control unit 33, a first correction unit 40, and a second correction unit 50.

[0026] First, the normal steering angle control portion other than the steering intervention correction will be described. A subtraction unit 31 calculates a steering angle deviation Δθ, which is the difference between the target steering angle and the detected steering angle. The steering angle deviation Δθ calculated by the subtraction unit 31 is multiplied by a gain of the value Kp stored in a steering angle control gain 32 (hereinafter referred to as steering angle control gain Kp) via multiplication units 44 and 45. The value resulting from this multiplication becomes the target steering angular velocity. In the steering angular velocity control unit 33, a subtraction unit 34 outputs the difference between the target steering angular velocity and the detected steering angular velocity as a steering angular velocity deviation. Also, in the steering angular velocity control unit 33, an adder 38 outputs a signal obtained by adding a proportional term obtained by multiplying the steering angular velocity deviation output from the subtraction unit 34 by a steering angular velocity proportional gain 35 to an integral term obtained by multiplying the steering angular velocity deviation by a steering angular velocity integral gain 36 and integrating the result in an integrator 37, as a steering angle control target current.

[0027] Next, the part related to the correction of steering intervention will be described. In summary, this steering intervention function provides a correction to the steering angle control according to the steering torque when the driver intervenes in steering during automatic steering by steering angle control based on the target steering angle, thereby enabling the steering angle to be changed in accordance with the driver's intention. In other words, during normal steering angle control, the steering angle follows and roughly matches the target steering angle, but with the steering intervention function, when the driver intervenes in steering, the actual steering angle is compensated to deviate from the target steering angle according to the steering torque. The steering angle control unit 21 realizes this steering intervention function by the first correction unit 40 and the second correction unit 50.

[0028] The first correction unit 40 includes a filter 41, an absolute value calculation unit 42, a first correction map 43, and multiplication units 44 and 45. The filter 41 is configured using a low-pass filter and a moving average to reduce high-frequency components, and reduces the high-frequency components of the steering torque (detected steering torque) detected by the torque sensor 5. The absolute value calculation unit 42 calculates the absolute value of the detected steering torque from which the high-frequency components have been reduced by the filter 41. The first correction map 43 outputs a first correction gain β for the absolute value of the detected steering torque from which the high-frequency components have been reduced. The multiplication unit 44 multiplies the first correction gain β output from the first correction map 43 by the steering angle control gain Kp stored in the steering angle control gain 32, and outputs the result as a first correction value 46. The multiplication unit 45 multiplies the steering angle deviation Δθ by the first correction value 46 output from the multiplication unit 44, and outputs the result as a pre-correction target steering angular velocity. An example of the first correction map 43 is shown in FIG. 4.

[0029] FIG. 4 is a diagram showing an example of a first correction map in the first embodiment. In FIG. 4, the horizontal axis represents the absolute value of the filtered detected steering torque, and the vertical axis represents the first correction gain β. The first correction map 43 defines the relationship between the absolute value of the detected steering torque and the first correction gain β. The value of the first correction gain β is set to 1 or less and is decreased as the steering torque increases. This means that, because the first correction gain β is multiplied by the steering angle control gain Kp, the steering angle control gain is corrected to be smaller as the absolute value of the steering torque increases. The effect of this will be described later.

[0030] The second correction unit 50 includes a phase compensator 51, a second correction gain 52, multiplication units 53 and 54, and an adder 55. The multiplication unit 53 multiplies the gain of the value α stored in the second correction gain 52 (hereinafter referred to as the second correction gain α) by the steering angle control gain Kp stored in the steering angle control gain 32. The multiplication unit 54 multiplies the phase-compensated detected steering torque by the value resulting from the multiplication by the multiplication unit 53, and outputs the multiplied output as a second correction value 56. The phase-compensated detected steering torque is calculated by the phase compensator 51 performing phase lead compensation to advance the phase of the detected steering torque or phase lag compensation to delay the phase of the detected steering torque. The adder 55 corrects the pre-correction target steering angular velocity output from the first correction unit 40 by adding the second correction value 56 to the pre-correction target steering angular velocity, and outputs the value resulting from the addition as the target steering angular velocity.

[0031] Here, the action and effect of the second correction unit 50 will be described. The second correction unit 50 adds a second correction value 56 proportional to the steering torque to the target steering angular velocity, and has a characteristic that the larger the steering torque, the greater the second correction value 56, i.e., the correction amount of the target steering angular velocity. Therefore, when the driver applies a steering torque to intervene in the steering, a corresponding target steering angular velocity is generated, causing the motor 6 to rotate and changing the actual steering angle. The component of the target steering angular velocity corresponding to the pre-correction steering angle deviation Δθ is the target steering angular velocity that attempts to control the steering angle to correspond to the target steering angle from the host controller 9. In contrast, the target steering angular velocity based on the second correction value 56 is due to the driver's steering intervention, making it possible to change the actual steering angle from the target steering angle at the driver's will.

[0032] Furthermore, the second correction unit 50 is a linear controller for steering torque because it adds the second correction value 56, which is obtained by multiplying the steering torque by a gain, to the target steering angular velocity. Therefore, it is necessary to consider the stability of the linear control loop that feeds back from the target steering angular velocity to the steering torque via the current, motor, and steering mechanism. Specifically, stability is evaluated using an open-loop transfer function from the second correction value 56 when the second correction value 56 is cut to the second correction value 56 that has returned after making a full loop through the control loop. It is desirable to evaluate stability both in a pattern in which the pre-correction target steering angular velocity is cut and in a pattern in which it is not. As the second correction gain α increases, the stability of this open-loop transfer function, i.e., the phase margin and gain margin, decrease. Therefore, the phase compensator 51 advances the phase to improve the phase margin, or delays the phase to reduce the gain near the crossover frequency and improve the gain margin.

[0033] However, there is a limit to how much stability can be improved by the phase compensator 51 or the like. For example, to advance the phase, the gain is amplified at frequencies higher than that frequency, amplifying noise, and there is a practical limit. Also, if the gain near the crossover frequency is further reduced, the phase also decreases at the same time, resulting in insufficient phase margin. As such, there is a limit to stability, and therefore there is an upper limit to the second correction gain α.

[0034] Therefore, if the first correction unit 40 is not present, i.e., the steering intervention correction by the second correction unit 50 alone is not sufficient to obtain a sufficient amount of correction, resulting in a problem that the steering torque required to provide a steering angle deviation from the target steering angle through steering intervention becomes large, preventing the driver from obtaining a light and satisfactory steering feeling. Because the second correction unit 50 has a configuration similar to the steering intervention compensation of Patent Document 1, this problem is a problem of the prior art. In the first embodiment of the present disclosure, the configuration includes the first correction unit 40, and therefore this problem can be solved.

[0035] Next, the operation and effect of the first correction unit 40 that can solve the above-mentioned problems in the first embodiment of the present disclosure will be described. The first correction unit 40 multiplies the steering angle deviation Δθ by a first correction value 46 obtained by multiplying the steering angle control gain Kp by a first correction gain β for the absolute value of the steering torque. The first correction unit 40 has a characteristic of reducing the first correction gain β as the absolute value of the steering torque increases. Therefore, when the driver applies steering torque to intervene in the steering, an effect equivalent to a corresponding decrease in the steering angle control gain Kp is exerted. As a result, the tracking ability of the actual steering angle relative to the target steering angle during the steering intervention decreases, the target steering angular velocity for tracking the target steering angle decreases, and the target steering angular velocity corrected by the second correction unit 50 becomes relatively larger. This allows the driver to intervene in the steering more smoothly with a smaller steering torque.

[0036] Furthermore, a configuration in which the steering angle control gain Kp is simply reduced as a function of time during steering intervention does not allow for comfortable steering intervention in accordance with the steering torque, so it is important to have a second correction unit 50 that corresponds to the steering torque.

[0037] The override characteristics of the steering intervention function (override function) of the present disclosure will now be described in more detail. The relationship between the steering torque T and the steering angle deviation Δθ is analyzed by approximating a static balanced state, i.e., a case where the steering angular velocity is zero. When the steering angular velocity is zero, if the steering angle control unit 21 has sufficient tracking capability, the target steering angular velocity will also be zero. As shown below, the first correction value 46 can be expressed by equation (1), the second correction value 56 by equation (2), and the pre-correction target steering angular velocity by equation (3).

[0038] First correction value=Kp×β (1) Second correction value=Kp×α×T (2) Pre-correction target steering angular velocity=first correction value×Δθ (3)

[0039] Furthermore, by substituting equation (1) into equation (3), the balance equation in the adder 55 can be expressed as follows: Kp×β×Δθ+Kp×α×T=target steering angular velocity=0 (4)

[0040] Furthermore, formula (4) can be rearranged to be expressed as the following formula (5): Δθ=−α / β×T (5)

[0041] In this way, the steering angle deviation Δθ from the target steering angle can be expressed as being proportional to the steering torque T, with the coefficient being α / β, that is, the value obtained by dividing the second correction gain α by the first correction gain β.

[0042] Here, the first correction gain β is the output of the first correction map 43 and is a function of the steering torque T. The relationship between the steering angle deviation Δθ and the steering torque T expressed by equation (5) is called the override characteristic. It can be seen that when the same steering angle deviation Δθ is given, the larger α / β is, the smaller the absolute value of the steering torque can be. An example of this override characteristic is shown in FIG. 5.

[0043] FIG. 5 is an example of an override characteristic diagram in the first embodiment. In FIG. 5, the horizontal axis represents the absolute value of the steering angle deviation Δθ, and the vertical axis represents the absolute value of the steering torque. The straight line representing only the second correction value in the diagram represents the case where the second correction gain α is set to approximately the maximum value. Since there is no first correction value, substituting β = 1 into equation (5) can be expressed as Δθ = -α × T. On the other hand, the curve representing the first and second correction values ​​allows the coefficient α / β to be increased by β, which is a value less than 1. As a result, it can be seen that, when the same steering angle deviation is given by steering intervention, the steering torque can be made smaller than when only the second correction value is used. In other words, a steering feeling with a lighter steering intervention than that of the prior art can be achieved.

[0044] Furthermore, by using the relational expression (5) of the override characteristic based on the first and second correction values, the steering feeling of the steering intervention can be easily designed. In other words, by calculating the expression (5) on paper, the steering characteristic can be easily designed, and furthermore, by illustrating it in the same manner as the override characteristic diagram shown in FIG. 5, it can be visually confirmed. Figure 6 shows the data measured from the actual design results.

[0045] Fig. 6 is an example of measured data of an override characteristic diagram in embodiment 1. The measured values ​​of the design results shown in Fig. 6 are similar to those of the override characteristic diagram shown in Fig. 5, and the characteristics intended in the design are generally well obtained. In other words, the effect of using the first and second correction values ​​by the first correction unit 40 and the second correction unit 50 in embodiment 1 has been verified.

[0046] If the normal steering control unit 20 is a typical assist control that uses the above-described assist map, the switching unit 23 may use the sum of the steering angle control target current and the target assist current as the target current when the steering angle control is in an active state. However, in this case, the target assist current acts as steering intervention compensation according to the steering torque by the driver during override, so the override characteristics change from those set by the first correction unit 40 and the second correction unit 50. In the first embodiment, the first correction unit 40, which is not available in the prior art, is provided, so sufficient steering intervention compensation can be obtained without adding the target assist current.

[0047] In each embodiment, the configuration that receives the target steering angle and the detected steering angle as inputs and outputs the pre-correction target steering angular velocity is called a target steering angular velocity calculation section.

[0048] Summary of First Embodiment As described above, the steering control device 10 according to this embodiment includes a normal steering control unit 20 that controls the torque applied to the steering mechanism based on steering of the steering mechanism by the driver. The steering control device 10 also includes a target steering angular velocity calculation unit that calculates a target steering angular velocity based on a signal that is approximately proportional to a steering angle deviation Δθ (an example of a deviation) between the steering angle of the steering mechanism and a target steering angle, a steering angular velocity control unit 33 that calculates a target current based on the target steering angular velocity, and a drive unit 25 that applies torque to the steering mechanism based on the target current. The steering control device 10 also includes a first correction unit 40 that multiplies the steering angle deviation Δθ (an example of a deviation) by a first correction value 46 that corresponds to a steering torque that the driver applies to the steering mechanism, and a second correction unit 50 that adds a second correction value 56 that corresponds to the steering torque to the target steering angular velocity.

[0049] As a result, the steering control device 10 can provide a light and good steering feeling when the driver intervenes in steering during steering angle control, and can simply achieve this function. For example, the steering control device 10 can provide a sufficient level of steering intervention compensation, reduce the steering torque when the driver intervenes in steering during steering angle control, and provide a light and good steering feeling. Furthermore, the steering control device 10 can specify the characteristics of the steering torque with respect to the steering angle deviation using the first correction unit 40 and the second correction unit 50, so that adjustments can be made to provide a good steering feeling easily.

[0050] Moreover, the first correction value 46 decreases as the absolute value of the steering torque increases.

[0051] As a result, the steering control device 10 can obtain greater steering intervention compensation as the absolute value of the steering torque correlated with the driver's intention becomes larger, thereby realizing a natural and light steering feeling.

[0052] Further, the second correction unit 50 adds a second correction value 56 to the pre-correction target steering angular velocity (an example of the target steering angular velocity) multiplied by the first correction value 46 .

[0053] As a result, the steering control device 10 can realize the second correction value 56 to be added to the pre-correction target steering angular velocity that has been reduced by the first correction gain β with a minimum value and a minimum configuration. For example, if the order is reversed, it may be necessary to increase the second correction value 56 in advance, or it may be necessary to use a map.

[0054] The steering control device 10 also includes a first correction map 43 (an example of a map) that defines the relationship between the steering torque and the first correction value 46. The first correction unit 40 multiplies the steering angle deviation Δθ (an example of a deviation) by the first correction value 46 that corresponds to the steering torque, based on the first correction map 43.

[0055] As a result, the steering control device 10 can design the override characteristics to be curved so as to optimize the steering feeling for the driver, and can also simply design the second correction value 56 to be a gain value at the limit of stability.

[0056] Furthermore, the first correction unit 40 calculates the first correction value 46 based on the steering torque in which the high frequency components of the steering torque have been reduced.

[0057] As a result, the steering control device 10 can eliminate unnecessary vibrations and achieve a comfortable steering feeling.

[0058] Further, the second correction unit 50 calculates a second correction value 56 based on the steering torque whose phase has been compensated for.

[0059] As a result, the steering control device 10 can improve the stability achieved by the second correction unit 50 and the steering angular velocity control system, and can improve the amount of steering intervention compensation.

[0060] In addition, the electric power steering device PS according to this embodiment includes a torque sensor 5 (an example of a steering torque detection unit) that detects the steering torque applied by the driver to the steering mechanism, a steering angle detection unit 4 that detects the steering angle of the steering mechanism, and the above-mentioned steering control device 10 that controls the drive unit 25 that applies torque to the steering mechanism based on the detected steering torque and steering angle.

[0061] As a result, the electric power steering device PS can provide a light and good steering feeling when the driver intervenes in steering during steering angle control, and can achieve this function simply. For example, the electric power steering device PS can provide a sufficient level of steering intervention compensation, reducing the steering torque when the driver intervenes in steering during steering angle control, thereby providing a light and good steering feeling. Furthermore, the electric power steering device PS can specify the characteristics of the steering torque relative to the steering angle deviation using the steering control device 10, so it can be easily adjusted to provide a good steering feeling.

[0062] In addition, the vehicle VE according to this embodiment is equipped with a vehicle speed sensor 8 (an example of a vehicle speed detection unit) that detects the speed of the vehicle VE, a higher-level controller 9 (an example of a controller) that outputs a target steering angle that is a target value for the steering angle of the steering mechanism, and the above-mentioned electric power steering device PS that controls the torque applied to the steering mechanism based on the vehicle speed detected by the vehicle speed sensor 8 and the target steering angle output from the higher-level controller 9.

[0063] This allows the vehicle VE to provide a light and pleasant steering feeling when the driver intervenes in steering during steering angle control, and this effect can be easily achieved. For example, the vehicle VE can provide a sufficient level of steering intervention compensation, reducing the steering torque when the driver intervenes in steering during steering angle control, thereby providing a light and pleasant steering feeling. Furthermore, the vehicle VE can specify the characteristics of the steering torque relative to the steering angle deviation using the electric power steering device PS, so that the steering feeling can be easily adjusted.

[0064] [Embodiment 2] Next, a description will be given of embodiment 2. The configurations of the electric power steering device and vehicle according to this embodiment are basically the same as the configurations of the electric power steering device PS and vehicle VE shown in Fig. 1. Therefore, a detailed description of the electric power steering device and vehicle according to this embodiment will be omitted.

[0065] The basic configuration of the steering control device according to this embodiment is the same as that of the steering control device 10 (control unit 11) shown in Fig. 2 of the first embodiment. However, there is a difference in the part related to the steering intervention correction of the steering angle control unit 21. This difference will be described below.

[0066] 7 is a block diagram showing an example of the internal configuration of the steering angle control unit in embodiment 2. The difference from embodiment 1 is that multiplication units 44 and 53 are not provided, and the steering angle control gain Kp is multiplied by the target steering angle speed output from the addition unit 55.

[0067] Specifically, the first correction unit 40 has a filter 41, an absolute value calculation unit 42, a first correction map 43, and a multiplication unit 45. The absolute value of the detected steering torque, from which high-frequency components have been reduced by the filter 41, is calculated by the absolute value calculation unit 42, and a first correction gain β for the absolute value of the detected steering torque, which is defined in the first correction map 43, is set as a first correction value 46. The multiplication unit 45 outputs an output obtained by multiplying the steering angle deviation Δθ by the first correction value 46 as the first corrected steering angle deviation. The filter 41, the absolute value calculation unit 42, and the first correction map 43 are the same as those in the first embodiment.

[0068] The second correction unit 50 has a phase compensator 51, a second correction gain 52, a multiplier 54, and an adder 55. The multiplier 54 multiplies the phase-compensated detected steering torque by the second correction gain α stored in the second correction gain 52, and outputs the result as a second correction value 56. The adder 55 corrects the first corrected steering angle deviation output from the first correction unit 40 by adding the second correction value 56, and outputs the result as a corrected steering angle deviation. The phase compensator 51 is the same as in the first embodiment. The steering angle control gain 32 multiplies the corrected steering angle deviation output from the second correction unit 50 by the steering angle control gain Kp, and outputs the result as a target steering angle speed.

[0069] As described above, in this embodiment, the steering control device 10 has the second correction unit 50 add the second correction value 56 to the steering angle deviation Δθ (one example of a deviation) multiplied by the first correction value 46 by the first correction unit 40, and further multiply the result by the steering angle control gain Kp to obtain the target steering angular speed. This embodiment is functionally equivalent to the first embodiment. This is because the target steering angular speed can be expressed in a simple mathematical formula in both cases using the following formula (6). Target steering angular speed = Kp × (β × Δθ + α × T) (6)

[0070] Therefore, the effects of this embodiment are similar to those of embodiment 1. Furthermore, the configuration of this embodiment is simpler in calculation than the configuration of embodiment 1 because there is one less multiplication.

[0071] [Embodiment 3] Next, a description will be given of embodiment 3. Like embodiment 2, this embodiment is an equivalent conversion of embodiment 1, and only the changed parts will be described.

[0072] 8 is a block diagram showing an example of the internal configuration of a steering angle control unit in embodiment 3. The difference from embodiment 1 is that multiplication units 44 and 53 are not provided, and the output of multiplication unit 45 is multiplied by steering angle control gain Kp. The basic configurations of first correction unit 40 and second correction unit 50 are the same as those in embodiment 2.

[0073] Specifically, in first correction unit 40, an absolute value calculation unit 42 calculates the absolute value of the detected steering torque, from which high-frequency components have been reduced by filter 41, and a first correction gain β for the absolute value of the detected steering torque, which is defined in a first correction map 43, is set as a first correction value 46. A multiplication unit 45 outputs an output obtained by multiplying the steering angle deviation Δθ by the first correction value 46 as the first corrected steering angle deviation. The filter 41, absolute value calculation unit 42, and first correction map 43 are the same as those in the first embodiment.

[0074] The steering angle control gain 32 multiplies the first corrected steering angle deviation output from the first corrector 40 by the steering angle control gain Kp, and outputs the result as a pre-correction target steering angle speed.

[0075] In the second correction unit 50, a multiplication unit 54 multiplies the phase-compensated detected steering torque by the gain of the value α2 stored in the second correction gain 52 (hereinafter referred to as the second correction gain α2), and outputs the result as a second correction value 56. An addition unit 55 corrects the pre-correction target steering angular velocity output from the steering angle control gain 32 by adding the second correction value 56 to the pre-correction target steering angular velocity, and outputs the value resulting from the addition as the target steering angular velocity. The phase compensator 51 is the same as in the first embodiment.

[0076] As described above, in the present embodiment, the steering control device 10 multiplies the first corrected steering angle deviation, which is obtained by first correcting the steering angle deviation Δθ (an example of a deviation) by the first correction value 46, by the steering angle control gain Kp in the steering angle control gain 32 to obtain a pre-correction target steering angular velocity (an example of a target steering angular velocity), and the second corrector 50 further adds the second correction value 56 to obtain a target steering angular velocity to be output to the steering angular velocity control unit 33. This embodiment is functionally equivalent to the first embodiment. The second correction gain α2 in this embodiment can be set as α2 = α × Kp using the second correction gain α of the first embodiment, and when the target steering angular velocity is expressed by a simple formula based on this setting, both can be expressed by the above-mentioned formula (6).

[0077] Therefore, the effects of this embodiment are similar to those of embodiment 1. Furthermore, the configuration of this embodiment is simpler in calculation than the configuration of embodiment 1 because there is one less multiplication.

[0078] [Fourth Embodiment] Next, a fourth embodiment will be described. Like the second and third embodiments, the fourth embodiment is an equivalent conversion of the first embodiment, and only the changed parts will be described.

[0079] 9 is a block diagram showing an example of the internal configuration of a steering angle control unit in the fourth embodiment. The difference from the first embodiment is that there are no multiplication units 44 and 53, and the steering angle control gain Kp is multiplied by the steering angle deviation Δθ. The basic configurations of the first correction unit 40 and the second correction unit 50 are the same as those in the second embodiment.

[0080] Specifically, the steering angle control gain 32 multiplies the steering angle deviation Δθ by the steering angle control gain Kp and outputs the result as the pre-correction target steering angle speed.

[0081] In first correction unit 40, absolute value calculation unit 42 calculates the absolute value of the detected steering torque, from which high frequency components have been reduced by filter 41, and sets the first correction gain β for the absolute value of the detected steering torque, which is defined in first correction map 43, as first correction value 46. Multiplication unit 45 multiplies the pre-correction target steering angular velocity output from steering angle control gain 32 by first correction value 46 and outputs the result. Filter 41, absolute value calculation unit 42, and first correction map 43 are the same as those in the first embodiment.

[0082] In the second correction unit 50, a multiplication unit 54 multiplies the phase-compensated detected steering torque by the second correction gain α2 stored in the second correction gain 52, and sets the output as a second correction value 56. An addition unit 55 performs correction by adding the second correction value 56 to the pre-correction target steering angular velocity output from the first correction unit 40, and outputs the value resulting from the addition as the target steering angular velocity. The phase compensator 51 is the same as in the first embodiment.

[0083] As described above, in the present embodiment, the steering control device 10 multiplies a pre-correction target steering angular velocity (an example of a target steering angular velocity) obtained by multiplying the steering angle deviation Δθ (an example of a deviation) by the steering angle control gain Kp in accordance with the steering angle control gain 32 by the first correction value 46 in the first correction unit 40, and further adds the second correction value 56 to the resultant value in the second correction unit 50 to obtain the target steering angular velocity to be output to the steering angular velocity control unit 33. The second correction gain α2 in this embodiment can be set as α2 = α × Kp using the second correction gain α in the first embodiment, and when the target steering angular velocity is expressed by a simple formula based on this setting, both can be expressed by the above-mentioned formula (6).

[0084] Therefore, the effects of this embodiment are similar to those of embodiment 1. Furthermore, the configuration of this embodiment is simpler in calculation than the configuration of embodiment 1 because there is one less multiplication.

[0085] [Embodiment 5] Next, a description will be given of embodiment 5. Like embodiments 2 to 4, embodiment 5 is an equivalent conversion of embodiment 1, and only the changed parts will be described.

[0086] 10 is a block diagram showing an example of the internal configuration of a steering angle control unit in embodiment 5. The differences from embodiment 1 are that the multiplication units 44 and 53 are not provided, the order of the first correction unit 40 and the second correction unit 50 is reversed, and the output of the addition unit 55 of the second correction unit 50 is multiplied by the steering angle control gain Kp.

[0087] Specifically, the second correction unit 50 has a phase compensator 51, a multiplier 54, an adder 55, a second correction map 57, and an absolute value calculator 58. As in the first embodiment, the phase compensator 51 performs phase lead compensation to advance the phase of the detected steering torque or phase lag compensation to delay the phase. The absolute value calculator 58 calculates the absolute value of the detected steering torque. As shown in FIG. 11 , the second correction map 57 defines a second correction gain α3 for the absolute value of the detected steering torque.

[0088] 11 is a diagram showing an example of a second correction map in Embodiment 5. In Fig. 11, the horizontal axis represents the absolute value of the detected steering torque, and the vertical axis represents the second correction gain α3. The second correction map 57 defines the relationship between the absolute value of the detected steering torque and the second correction gain α3.

[0089] The second correction map 57 outputs a second correction gain α3 for the absolute value of the detected steering torque calculated by the absolute value calculation unit 58. The multiplication unit 54 calculates a value obtained by multiplying the phase-compensated detected steering torque by the second correction gain α3 as a second correction value 56. The addition unit 55 adds the second correction value 56 to the steering angle deviation Δθ, and outputs the added signal as a corrected steering angle deviation.

[0090] The steering angle control gain 32 multiplies the corrected steering angle deviation output from the second correction unit 50 by the steering angle control gain Kp, and outputs the result as a pre-correction target steering angle speed.

[0091] In first correction unit 40, a calculation unit 42 calculates the absolute value of the detected steering torque, from which high-frequency components have been reduced by filter 41, and a first correction gain β for the absolute value of the detected steering torque, which is defined in a first correction map 43, is set as a first correction value 46. A multiplication unit 45 multiplies the pre-correction target steering angular velocity output from steering angle control gain 32 by first correction value 46, and outputs the result as the target steering angular velocity. Filter 41, absolute value calculation unit 42, and first correction map 43 are the same as those in the first embodiment.

[0092] As described above, in the present embodiment, the steering control device 10 multiplies the corrected steering angle deviation, which is obtained by the second correction unit 50 adding the second correction value 56 to the steering angle deviation Δθ (an example of a deviation), by the steering angle control gain Kp in the steering angle control gain 32 to obtain a pre-correction target steering angular velocity (an example of a target steering angular velocity), and the first correction unit 40 further adds the first correction value 46 to obtain a target steering angular velocity to be output to the steering angular velocity control unit 33. This embodiment can be made functionally equivalent to the first embodiment depending on how the second correction gain α3 is set. This is because the second correction gain α3 of this embodiment can be set as α3 = α / β using the second correction gain α of the first embodiment, and when the target steering angular velocity is expressed by a simple formula based on this setting, both can be expressed by the above-mentioned formula (6).

[0093] As shown in FIG. 11, this setting can be achieved by setting the shape of the first correction gain β shown in FIG. 4 to a symmetrical shape with a boundary of 1. In other words, this setting is such that the change in the value of the first correction gain β shown in FIG. 4 is absorbed by the correction gain α3 shown in FIG. 11.

[0094] Specifically, the first line of the following equation (7) is a mathematical expression showing the configuration of the fifth embodiment, and by substituting α / β for the value of the second correction gain α3, the equation on the second line is obtained, which is found to be the same as the above-mentioned equation (6). Target steering angular velocity=Kp×β×(Δθ+α3×T) (7) =Kp×β×(Δθ+α / β×T) =Kp×(β×Δθ+α×T)

[0095] Therefore, the effects of this embodiment are similar to those of embodiment 1. Furthermore, the configuration of this embodiment has one more map than the configuration of embodiment 1, so although it is more complex, it has a higher degree of freedom.

[0096] Next, a sixth embodiment will be described. In this embodiment, the second correction gain 52 and the multiplication unit 54 of the second correction unit 50 shown in Fig. 8 of the third embodiment are changed to a second correction map 59. The changed parts will be described with reference to Figs. 12 and 13.

[0097] Fig. 12 is a block diagram showing an example of the internal configuration of the steering angle control unit in the sixth embodiment. As described above, only the second correction unit 50 is different from Fig. 8 of the third embodiment.

[0098] The second correction unit 50 includes a second correction map 59 in which a second correction value 56 (second correction gain α4) for the detected steering torque after phase compensation is defined. The second correction map 59 outputs the second correction value 56 for the detected steering torque after phase compensation by the phase compensator 51 as the second correction value 56. The adder 55 performs correction by adding the second correction value 56 to the pre-correction target steering angular velocity output from the steering angle control gain 32, and outputs the value resulting from this addition as the target steering angular velocity. The phase compensator 51 is the same as in the first embodiment.

[0099] The second correction map 59 may have characteristics as shown in FIG. 13, for example. FIG. 13 is a diagram showing an example of the second correction map in the sixth embodiment. In FIG. 13, the horizontal axis represents the detected steering torque, and the vertical axis represents the second correction value 56. The slope of the curve shown in this diagram corresponds to the gain α2 in the third embodiment, and if the slope is kept constant and the curve is set as a straight line, it becomes equivalent to the third embodiment. In this embodiment, the second correction value 56 relative to the detected steering torque is specified as a map, and therefore, in addition to the effects of the third embodiment, it is also possible to set a more precise steering feeling.

[0100] The steering intervention compensation disclosed in Patent Document 1 corresponds to a configuration in which the gain α of the second correction unit is a map, and is similar to the second correction unit of the present embodiment. However, even if it is a map, the maximum gradient thereof is limited from the viewpoint of stability, and therefore, it is not possible to obtain a steering intervention correction amount greater than that obtained when a constant gain is used.

[0101] Seventh Embodiment Next, a seventh embodiment will be described. This embodiment differs from the first embodiment in the configuration of the first correction unit 40. The configuration is shown in FIG.

[0102] Fig. 14 is a block diagram showing an example of the internal configuration of a first correction unit in a steering angle control unit in embodiment 7. Fig. 14 shows only the first correction unit 40 in the steering angle control unit 21 in this embodiment, and the other configuration is the same as that of embodiment 1 shown in Fig. 3. The difference from embodiment 1 shown in Fig. 3 is that the first correction unit 40 further includes a steering angle system correction gain calculation unit 60 and a multiplication unit 61.

[0103] A steering angle system correction gain calculation unit 60 calculates a steering angle system correction gain that decreases in a range of 1 or less as the absolute value of the steering angle speed increases. A multiplication unit 61 multiplies the steering angle system correction gain by the first correction gain β output from the first correction map 43, and outputs a corrected first correction gain. A multiplication unit 44 multiplies the corrected first correction gain by the steering angle control gain Kp stored in the steering angle control gain 32, and outputs a first correction value 46.

[0104] According to the configuration of this embodiment, the first correction value 46 decreases as the absolute value of the steering angular velocity increases, so that when the absolute value of the steering angular velocity is large, the driver can more easily intervene in the steering.

[0105] Conversely, if the steering angle system correction gain calculation unit 60 is configured to calculate a steering angle system correction gain whose value increases in a range of 1 or more in accordance with an increase in the absolute value of the steering angular velocity, it becomes difficult for the steering intervention correction amount to be applied when the absolute value of the steering angular velocity is large, and a solid response can be obtained when the velocity is high.

[0106] As a further modification, the steering angle system correction gain calculation unit 60 may calculate a steering angle system correction gain that decreases in a range of not more than 1 as the absolute value of the steering angle deviation increases. In this case, when the absolute value of the steering angle deviation is large, the driver can more easily intervene in the steering.

[0107] In this way, in the steering control device 10 according to this embodiment, the first correction unit 40 corrects the first correction value based on the steering angle (e.g., steering angle deviation) or the steering angular velocity, thereby enabling the driver to intervene in steering more easily.

[0108] Eighth Embodiment Next, an eighth embodiment will be described. This embodiment differs from the first embodiment in the configuration of the first correction unit 40. The configuration is shown in FIG.

[0109] Fig. 15 is a block diagram showing an example of the internal configuration of a first correction unit in a steering angle control unit in the eighth embodiment. Fig. 15 shows only the first correction unit 40 in the steering angle control unit 21 in this embodiment, and the other configuration is the same as that in the first embodiment shown in Fig. 3. The differences from the first embodiment shown in Fig. 3 are that the first correction unit 40 does not include an absolute value calculation unit 42, that it includes a vehicle system correction coefficient calculation unit 80, and that the first correction map 43 is variable.

[0110] The vehicle system correction coefficient calculation unit 80 determines whether there is a margin for a safe lateral position area in the left / right direction of the vehicle lateral position, i.e., in the positive or negative direction, based on the vehicle lateral position deviation information, and outputs the determination result. The vehicle lateral position deviation information is, for example, the distance from the white lines on both the left and right sides of the road lane, and is transmitted from the host controller 9. For example, the vehicle system correction coefficient calculation unit 80 determines the result as Determination A when there is a margin in the positive direction, and determines the result as Determination B when there is a margin in the negative direction.

[0111] The first correction map 43 switches the first correction gain β in accordance with the determination result. Fig. 16 is a diagram showing an example of the first correction map in the eighth embodiment. In Fig. 16, the horizontal axis represents the filtered detected steering torque, and the vertical axis represents the first correction gain β. For example, the first correction map 43 switches the first correction gain β as shown in Fig. 16 in accordance with the determination result, and outputs the first correction gain β, which is the output of the map, in accordance with the filtered steering torque.

[0112] As described above, in the steering control device 10 according to this embodiment, the first correction unit 40 corrects the first correction value 46 based on the lateral margin of the vehicle VE. As a result, when the steering control device 10 determines, for example, that there is margin in the positive direction in judgment A, the first correction gain β decreases when the driver applies steering torque in the positive direction, resulting in a large steering intervention correction amount, and a steering angle deviation can be applied with a small steering torque. On the other hand, when the driver applies steering torque in the negative direction, the first correction gain β increases, making it difficult to intervene in the steering. Furthermore, in judgment B, the first correction gain β increases as the steering torque increases, resulting in a similar effect when there is margin in the negative direction. Therefore, steering intervention can be performed smoothly on the side with lateral margin, and a firm response can be provided on the side with less margin, enabling safe and secure steering.

[0113] Ninth Embodiment Next, a ninth embodiment will be described. This embodiment differs from the first embodiment in the configuration of the first correction unit 40. The configuration is shown in FIG.

[0114] Fig. 17 is a block diagram showing an example of the internal configuration of a first correction unit in a steering angle control unit in the ninth embodiment. Fig. 17 shows only the first correction unit 40 in the steering angle control unit 21 in this embodiment, and the other configurations are the same as those in the first embodiment shown in Fig. 3. The differences from the first embodiment shown in Fig. 3 are that the first correction unit 40 does not include the absolute value calculation unit 42, that it includes an emergency correction coefficient calculation unit 70, and that the first correction map 43 is variable.

[0115] When an obstacle is detected in the traveling direction of the vehicle VE by, for example, a camera or radar, the emergency correction coefficient calculation unit 70 receives the result of the determination made by the upper controller 9 regarding the necessity of emergency steering as the presence or absence of an emergency avoidance state (a state in which emergency avoidance is necessary).The emergency correction coefficient calculation unit 70 then outputs the received presence or absence of the emergency avoidance state as a determination result.

[0116] The first correction map 43 switches the first correction gain β depending on the determination result. For example, when the determination result indicates that an emergency avoidance state exists, the first correction map 43 sets the first correction gain β to be smaller than when the emergency avoidance state does not exist.

[0117] In this way, in the steering control device 10 according to the present embodiment, the first correction unit 40 corrects the first correction value 46 based on whether or not emergency steering is necessary for the vehicle VE (whether or not an emergency avoidance state is present). This allows the steering control device 10 to more easily intervene in steering when in an emergency avoidance state, enabling safe and secure steering.

[0118] Although the embodiments have been described above in detail with reference to the drawings, the specific configurations are not limited to these embodiments, and each embodiment can be modified or omitted as appropriate. In other words, the present disclosure is not limited to the above-described embodiments, and can be freely modified within the scope of the present disclosure.

[0119] For example, the electric power steering device PS described in the above embodiment may be of a column type or a rack-and-pinion type. Furthermore, the device may also be applied to a steer-by-wire reaction force device or the like, as long as it controls the steering angle based on the target steering angle of the host controller 9. Furthermore, the figures used in the description of the above embodiment are merely examples, and the present invention is not limited to these.

[0120] In the above embodiment, the target steering angle is calculated by the host controller 9, but it may be calculated within the steering control device 10.

[0121] Furthermore, in the above embodiment, the switching unit 23 switches between the target current from the normal steering control unit 20 and the target current from the steering angle control unit 21. However, when the steering angle control operation signal indicates the steering angle control operation state, the target current may be the sum of the target assist current from the normal steering control unit 20 and the steering angle control target current from the steering angle control unit 21. In the case of a target assist current based on a typical assist map, it can be used as steering intervention compensation that is approximately proportional to the steering torque. In that case, however, it is necessary to limit the steering angle control target current, and the override characteristics will deviate from the characteristics based on the above-mentioned mathematical formula.

[0122] The control unit 11 may have an internal computer system. A program for implementing at least some of the functions of the control unit 11 may be recorded on a computer-readable recording medium, and the program recorded on the recording medium may be read into a computer system and executed to perform processing in each component of the control unit 11. Here, "reading a program recorded on a recording medium into a computer system and executing it" includes installing the program into a computer system. The term "computer system" here includes an OS and hardware such as peripheral devices.

[0123] Furthermore, a "computer system" may include multiple computer devices connected via a network including the Internet or communication lines such as a WAN, LAN, or dedicated line. Furthermore, a "computer-readable recording medium" refers to portable media such as flexible disks, optical magnetic disks, ROMs, and CD-ROMs, as well as storage devices such as hard disks built into a computer system. Thus, the recording medium storing the program may be a non-transitory recording medium such as a CD-ROM.

[0124] The recording medium also includes internal or external recording media accessible from a distribution server for distributing the program. The program may be divided into multiple parts, downloaded at different times, and then combined by the components of the control unit 11. Each divided program may be distributed by a different distribution server. Furthermore, the term "computer-readable recording medium" also includes a medium that stores a program for a certain period of time, such as volatile memory (RAM) within a computer system that serves as a server or client when a program is transmitted over a network. The program may also be a medium for implementing part of the above-described functions. Furthermore, the program may be a so-called differential file (differential program) that can realize the above-described functions in combination with a program already stored in the computer system.

[0125] 1...Steering wheel, 2...Steering shaft, 4...Steering angle detection section, 5...Torque sensor, 6...Motor, 7...Deceleration mechanism, 8...Vehicle speed sensor, 9...Host controller, 10...Steering control device, 11...Control unit, 20...Normal steering control section, 21...Steering angle control section, 23...Switching section, 24...Differentiation section, 25...Drive section, 26...Current control section, 31...Subtraction section, 32...Steering angle control gain, 33...Steering angle velocity control section, 34...Subtraction section, 35...Steering angle velocity proportional gain, 36...Steering angle velocity product Minute gain, 37...integration section, 38...addition section, 40...first correction section, 41...filter, 42...absolute value calculation section, 43...first correction map, 44, 45...multiplication section, 46...first correction value, 50...second correction section, 51...phase compensator, 52...second correction gain, 53, 54...multiplication section, 55...addition section, 56...second correction value, 58...absolute value calculation section, 57, 59...second correction map, 60...steering angle system correction gain calculation section, 61...multiplication section, VE...vehicle, PS...electric power steering device

Claims

1. A steering control device comprising: a normal steering control unit that controls the torque applied to the steering mechanism based on steering of the steering mechanism by a driver; a target steering angular velocity calculation unit that calculates a target steering angular velocity based on a signal that is approximately proportional to the deviation between the steering angle of the steering mechanism and a target steering angle; a steering angular velocity control unit that calculates a target current based on the target steering angular velocity; a drive unit that applies torque to the steering mechanism based on the target current; a first correction unit that multiplies the deviation or the target steering angular velocity by a first correction value corresponding to a steering torque that corresponds to the torque applied by the driver to the steering mechanism; and a second correction unit that adds a second correction value corresponding to the steering torque to the deviation or the target steering angular velocity.

2. The steering control device according to claim 1, wherein the first correction value decreases as the absolute value of the steering torque increases.

3. A steering control device according to claim 1 or 2, wherein the second correction unit adds the second correction value to the deviation or the target steering angular velocity multiplied by the first correction value.

4. A steering control device according to any one of claims 1 to 3, further comprising a map defining the relationship of the first correction value to the steering torque, and the first correction unit multiplies the deviation or the target steering angular velocity by the first correction value corresponding to the steering torque based on the map.

5. A steering control device according to claim 1, wherein the first correction unit corrects the first correction value based on the steering angle or steering angular velocity of the steering mechanism.

6. The steering control device according to claim 1, wherein the first correction unit corrects the first correction value based on a margin in the left-right direction of the vehicle.

7. The steering control device according to claim 1, wherein the first correction unit corrects the first correction value based on whether or not there is a need for emergency steering of the vehicle.

8. A steering control device according to any one of claims 1 to 5, wherein the first correction unit calculates the first correction value based on the steering torque in which high frequency components of the steering torque have been reduced.

9. A steering control device according to any one of claims 1 to 6, wherein the second correction unit calculates a second correction value based on the steering torque obtained by compensating for the phase of the steering torque.

10. An electric power steering device comprising: a steering torque detection unit that detects the steering torque applied by a driver to a steering mechanism; a steering angle detection unit that detects the steering angle of the steering mechanism; and a steering control device according to any one of claims 1 to 7 that controls a drive unit that applies torque to the steering mechanism based on the detected steering torque and steering angle.

11. A vehicle comprising: a vehicle speed detection unit that detects the speed of the vehicle; a controller that outputs a target steering angle that is a target value for the steering angle of the steering mechanism; and an electric power steering device as described in claim 10 that controls the torque applied to the steering mechanism based on the vehicle speed detected by the vehicle speed detection unit and the target steering angle output from the controller.

Images