JP4660947B2 - Electric power steering device - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
  The present invention relates to an in-vehicle electric power steering apparatus that assists the steering of a vehicle driver.
[0002]
[Prior art]
  Based on a desired steering feeling model and a real time detection value such as a steering angle θ of the steering wheel (that is, a steering wheel rotation angle) and a vehicle speed V, the steering torque q applied to the steering wheel by the driver should be reached. An “electric power steering device” has been devised that calculates the target value h and controls the auxiliary torque output motor so that the steering torque q follows the target value h.
[0003]
  FIG. 8 is a control block diagram illustrating an outline of a general control method of the electric power steering apparatus using the steering torque control means (62) set so as to ensure robust stability.
  The steering angle θ of the steering wheel output from the steering angle sensor 16 is differentiated by the steering angle differentiation means 64 and input to the target value generation means 61. The steering angle θ is also input to the target value generating means 61. The target value generating unit 61 generates a target value h of the steering torque based on the vehicle speed V, the steering angle θ, the angular speed ω (= dθ / dt), or the like according to a desired steering feeling model.
[0004]
  The steering torque control means 62 is configured to reduce the current based on the deviation (hq) between the target value h output from the target value generation means 61 and the steering torque q detected by the torque sensor 12. The command value setting means 63 allows the current command value I_AIs calculated. That is, the current command value I_AIs calculated so that the steering torque q follows the target value h. The current command value calculation means 63 is, for example, a compensator (robust controller) composed of a PID controller or the like, so that the feedback loop of the steering torque q is stabilized (robust stability is ensured). ) Is set.
  Therefore, as the current command value calculation means 63, for example, a transfer function whose transfer function is set by the H∞ control theory may be used.
[0005]
  FIG. 9 is a control block diagram illustrating a control method (example 1) of the target value generating means 61 (FIG. 8) that is currently devised.
  For example, in this control block diagram (FIG. 9), first, the target value h is determined according to the steering angle θ, the vehicle speed V, and the angular speed ω.₁Next, the gain G according to the vehicle speed V at that time is determined from the map M2.₁To decide.
[0006]
  Thereafter, the target value h for the angular velocity ω from the map M3.₂And then gain G according to vehicle speed V from map M4.₂Furthermore, these two target values h₁, H₂And gain G_1,G₂Is used to finally obtain the target value h in the calculation format as shown in the following equations (1) and (2).
[Expression 1]
  h = E (V, θ, ω) (1)
[Expression 2]
  E (V, θ, ω) = G₁・ H₁+ G₂・ H₂                    ... (2)
[0007]
  For example, the target value h can be determined so as to obtain a steering feeling according to the vehicle speed, steering angle, and steering angular velocity at that time, and the detected steering torque q is determined in this way. The steering torque control means 62 can be operated so as to follow the target value h.
  That is, a predetermined steering feeling model can be realized while ensuring robust stability by the control method as described above.
[0008]
  FIG. 10 shows a control block diagram of another control method (example 2) of the conventional target value generating means (corresponding to 61 in FIG. 8). In this control method (example 2), the function E of (1) is defined in the form of the following equations (3) to (5).
[Equation 3]
  E (V, θ, ω) = τ + T_D                                  ... (3)
[Expression 4]
  τ = E1 (V, θ) (4)
[Equation 5]
  T_D= E2 (ω) (5)
  However, here, the function E1 is a multivalent function related to the steering angle θ and has hysteresis characteristics. “Increase / return determination means” in the figure is means for uniquely determining a reaction force command value based on a multivalent function having hysteresis characteristics. The function E2 may be a linear expression, for example, and can be realized by a relatively simple arithmetic process such as multiplying a predetermined damper gain by the angular velocity ω.
[0009]
  Using such a calculation format, the argument ω (independent variable) is separated from the other arguments (independent variables V, θ), thereby making it easier to design, manufacture, and adjust the hysteresis characteristic (function E1). Therefore, it is possible or much easier to realize a desired steering feeling that is more suitable for the driver's sense.
[0010]
  Further, by separating the argument ω (independent variable) from the other arguments (independent variables V and θ) using such a calculation format, “displacement of angular velocity ω as shown in the hysteresis map M3 in FIG. Since the function very sensitive to the vicinity of the origin ”can be excluded from the components of the function E, this may suppress the vibration of the steering wheel.
[0011]
[Problems to be solved by the invention]
  However, when a steering angle sensor having a relatively long detection cycle of the steering angle θ of the steering wheel (steering wheel) (hereinafter sometimes referred to as “steering wheel angle”) is used, etc. Since the change amount (displacement) of the steering angle θ of the steering wheel tends to be large, a vibration component also appears in the torque command value, and as a result, the steering wheel may vibrate.
[0012]
  FIG. 11 is a graph illustrating the behavior of the steering wheel of the electric power steering apparatus using the conventional target value generating means (the control method (example 2) in FIG. 10). As can be seen from FIG. 11B, when the detection angle of the steering wheel angle is relatively long, such as about 20 to 40 ms, the steering wheel angle (steering angle θ) changes stepwise with time. A vibration component also appears in the torque command value (or current command value) for the motor, and as a result, the handle may vibrate.
[0013]
  The present invention has been made to solve the above-described problems, and its object is to vibrate the steering wheel even when a relatively inexpensive steering angle sensor having a relatively long steering angle detection cycle is used. It is to realize a difficult electric power steering device.
[0014]
[Means for Solving the Problem, Action, and Effect of the Invention]
  In order to solve the above problems, the following means are effective.
  That is, the first means includes a motor that applies assist torque to assist the steering of the vehicle to the steering mechanism, a torque sensor that detects the steering torque q applied to the steering wheel by the driver, and the vehicle traveling speed (vehicle speed V). In an electric power steering apparatus having a vehicle speed sensor for detecting the steering wheel, a steering angle sensor for detecting the rotation angle (steering angle θ) of the steering wheel, and a motor control device for driving and controlling the motor, based on the detected value of the steering angle θ With the steering angle extrapolation process, the estimated value Θ of the steering angle θ at or near the current time is shorter than the output period of the steering angle sensor.FixedRudder angle estimation means to be calculated periodically and at least an estimated value ΘAnd at least one of the rotational angular velocity ω and the vehicle speed V of the steering wheel.Based on the target value generating means for calculating the target value h that the steering torque q should reach, and the command value I of the motor drive current so that the steering torque q follows the target value h._AAnd a steering torque control means for determining.
[0015]
  By introducing the steering angle estimating means of the present invention that executes the steering angle extrapolation processing as described above, the steering wheel angle is calculated (estimated) relatively accurately in a cycle shorter than the detection cycle of the steering wheel angle (steering angle θ). It becomes possible. For this reason, according to said 1st means, even when the comparatively cheap steering angle sensor with a comparatively long steering angle detection period is used, a vibration of a steering wheel can be suppressed.
  Therefore, according to the present invention, it is possible to configure an electric power steering device in which the steering wheel hardly vibrates at a relatively low cost.
[0016]
  MaEyesIn the standard value generating means,In addition to the estimated value Θ,Further, the target value h is calculated based on at least one of the steering wheel rotational angular velocity ω and the vehicle speed V.BecauseFor example, the first means can be applied even under the configuration of the target value generating means and the like illustrated in FIG. 10 described above, and thus an electric power steering apparatus that is less prone to handle vibration can be configured.
[0017]
  In addition, the second means includes a motor that applies an assist torque to assist the steering of the vehicle to the steering mechanism, a torque sensor that detects the steering torque q applied to the steering wheel by the driver, and a vehicle traveling speed (vehicle speed V). In an electric power steering apparatus having a vehicle speed sensor for detecting the steering wheel, a steering angle sensor for detecting the rotation angle (steering angle θ) of the steering wheel, and a motor control device for driving and controlling the motor, based on the detected value of the steering angle θ Based on the detected value of the steering angle θ, using the detected angular velocity vibration mitigating means for removing the vibration component in the specific frequency band of the rotational angular velocity of the steering wheel calculated in the above and the rotational angular velocity ω calculated by the detected angular velocity vibration mitigating means The rudder angle extrapolation process calculates the estimated value Θ of the rudder angle θ at or near the present time approximately at a period shorter than the rudder angle sensor output period. An estimation means, a target value generation means for calculating a target value h to be reached by the steering torque q based on at least the estimated value Θ, and a motor drive current command so that the steering torque q follows the target value h. Value I _A And a steering torque control means for determining.
  The third means is the above-mentioned first1 handIn the stage, the vibration component in the specific frequency band of the rotational angular velocity of the steering wheel calculated based on the detected value of the steering angle θ is removed.InspectionOutgoing angular velocity vibration mitigation handStepIn the steering angle estimating means, the estimated value Θ is calculated based on the rotational angular velocity ω calculated by the detected angular velocity vibration mitigating means.
[0018]
  By using such detection angular velocity vibration mitigating means, it is possible to make the fluctuation of the rotational angular velocity ω, which tends to be unstable due to a differential operation, etc., to a relatively stable state. It is possible to intensively suppress a vibration component having a frequency that easily causes discomfort. In addition, noise that tends to appear in the numerical value of the rotational angular velocity ω can be reduced.
[0019]
  Therefore, in the above-described steering angle estimating means, if the estimated value Θ of the steering angle is calculated based on the rotational angular velocity ω calculated by the detected angular velocity vibration mitigating means, the estimation accuracy of the steering angle is improved and the estimated value Θ is related. A vibration suppressing effect is obtained.
  That is, by these actions, it is possible to more reliably suppress the vibration of the torque command value and the vibration of the handle itself.
[0020]
  The fourth means is the above-described target value h, command value in any one of the first to third means.I _A ofBy shortening the output cycle using a predetermined interpolation / extrapolation processTarget value h, command value I _A ofReduce the amount of fluctuation per output cycleFingerNormal vibration mitigation handStepIs to provide.
[0021]
  According to this means, it is possible or easy to configure a control command (torque command) with a finer period. For this reason, the vibration of the handle can be more reliably or easily suppressed.
  In addition, according to this means, independently of the specification such as the steering angle detection cycle of the steering angle sensor, it is independently dependent only on the specification of the steering torque detection cycle or control cycle of the system constituting the robust torque loop. The output cycle of the target value h can be determined. For this reason, the independence of the robust torque loop constituent part and the target value generating means is greatly improved, the design time and adjustment time of each part can be shortened, and the productivity is improved.
[0022]
  The fifth means is a target value generating means of any one of the first to fourth means, wherein a basic term that generates a basic term that depends on at least the estimated value Θ based on a predetermined hysteresis characteristic. The generating means and the damper term generating means for generating a damper term depending on at least the rotational angular velocity ω of the steering wheel are provided independently or in parallel.
[0023]
  According to this means, for example, a simple configuration represented by the above-described control method (example 2) based on the above formulas (3) to (5) can be adopted. In addition, the independence or parallelism of the functions E1 and E2 makes it easy to design, manufacture, and adjust the target value generating means. Moreover, if this means is used, the vibration of the handle can be suppressed in substantially the same manner as the above-described operation principle.
  Further, according to this means, it is possible or easy to improve the “convergence” typified by the convergence characteristic of the steering wheel to the equilibrium point when the driver releases his / her hand.
[0024]
  The sixth means is robust against model errors and disturbances in the control model of the electric power steering device in the target value generating means or the steering torque control means of any one of the first to fifth means. Using a transfer function set to ensure stability, target value h, command valueI _A TheIs to decide.
[0025]
  By such means, the target value does not affect the stability of the steering torque feedback loop, so there is no need to readjust the steering torque control means in the steering torque feedback loop, and the steering feeling can be adjusted efficiently. Can be. Since the target value can be set to an arbitrary size, the steering handle can be set to an arbitrary weight.
  Further, by generating a target value based on the vehicle speed, the rotation angle of the steering wheel, and the rotation angular velocity of the steering wheel, it is possible to give an optimum steering feeling to the running state and the steering state.
[0026]
  Further, the steering torque control means generates a current command value using a model error of the control model of the electric power steering apparatus and a transfer function set so as to ensure robust stability against disturbance. Since the stability is increased and the steering handle vibration is further suppressed, a more optimal steering feeling can be provided.
  As for the characteristic of the target value with respect to the vehicle speed v, the target value may be reduced as the vehicle speed v increases. As a result, the steering feeling can be reduced as the vehicle speed increases.
[0027]
  As for the characteristic of the target value with respect to the steering angle θ, the target value may be increased as the steering angle θ increases. By setting in this way, the characteristic that the steering feeling becomes heavier as the steering wheel is cut is obtained.
  Further, the target value may be increased as the steering angular velocity ω (= dθ / dt) increases. With this setting, for the same reason as described above, the steering handle can have a heavier steering feeling as the steering angular velocity increases.
[0028]
  Further, the target torque characteristics may be set by any combination thereof.
  Thus, by setting the target value according to the running state and the steering state, it is possible to obtain an optimum steering feeling in the state at that time.
[0029]
  Further, the target value may be changed by an arbitrary function by combining two or three of the vehicle speed, the steering angle, and the steering angular velocity. Further, the target value may be changed in consideration of the steering frequency or the like. That is, when the steering frequency is high, continuous curve driving can be considered. In this case, traveling stability can be maintained by making the steering handle a heavy steering feeling.
  By the above means, the above-mentioned problems can be effectively solved.
[0030]
DETAILED DESCRIPTION OF THE INVENTION
  Hereinafter, the present invention will be described based on specific examples. However, the present invention is not limited to the following examples.
  FIG. 1 is a logical hardware configuration diagram of an electric power steering apparatus 100 according to a specific embodiment of the present invention.
[0031]
  The steering wheel 10 is fixed to a steering shaft 11, and a torque sensor 12 is disposed on the steering shaft 11. The manual torque applied to the steering shaft 11 is transmitted to the rack 14 via the pinion gear 13 and used to change the direction of the steering wheels 41 and 42. As is well known, the torque sensor 12 detects torque generated when the steering wheel 10 is operated and the steering shaft 11 is twisted. That is, when steering at a constant speed, the torque obtained by subtracting the assist torque from the motor from the reaction torque received by the steered wheels 41 and 42 from the road surface is equal to the manual torque applied for steering by the driver. This torque is detected as the twisting torque of the steering shaft 11.
[0032]
  The output signal from the torque sensor 12 is sampled at a minute time interval by the A / D converter 18, converted into a digital signal, and input to the CPU 20. The vehicle speed v output from the vehicle speed sensor 15 and the steering angle θ output from the steering angle sensor 16 are input to the CPU 20. The CPU 20 is connected to a ROM 21 that stores programs and maps, and a RAM 22 that stores various data. An output signal from the CPU 20 is input to a driver circuit 25, and an electric motor 31 incorporating a speed reducer is driven by the driver circuit 25 (electric motor driving means). As the electric motor 31 rotates, assist torque is applied to the steering wheels 41 and 42 via the pinion gear 32 and the rack 14. The target value generating means 61 and the steering torque control means 62 are constituted by a computer system comprising these CPU 20, ROM 21, RAM 22, and the like.
[0033]
  In addition, the above structure has the mechanical system (power steering system) which has said 10-14, 31, 32, 41, 42, a reduction gear, etc., and comprises a control object, 15, 16, 18, 20, 21 , 22, 25, and a controller system that has a power supply circuit (not shown) and the like and realizes electronic control.
[0034]
  FIG. 2 is a control block diagram showing a logical outline of the control method of the electric power steering apparatus 100 described above. The “torque command generator” in FIG. 2 constitutes a portion corresponding to the target value generator 61 in FIG. 8, and the compensator (robust controller) 63 is a current command value calculator 63 in FIG. It corresponds to. That is, the torque command generation unit (target value generation unit) of the present embodiment has a reaction force command value calculation unit (basic term generation unit) and a damper term generation unit in parallel as can be seen from FIG. 2 (or FIG. 3). The steering torque target value is substantially similar to the above-described control method (example 2) in a format that substantially conforms to the above-described equations (3) to (5) and equation (1). Calculate h.
[0035]
  However, in more detail, as illustrated in “a more detailed control block diagram of the target value generation unit” in FIG. 3, the torque command generation unit (target value generation unit) of the present embodiment has an LPF processing unit 402 ( Detection angular velocity vibration mitigating means), rudder angle estimation processing unit 403 (steering angle estimation means), target value correction processing unit 408 (command value vibration mitigating means), etc. Thus, according to the electric power steering apparatus 100 of the present embodiment, the vibration of the steering wheel can be effectively suppressed by these actions.
[0036]
  Hereinafter, the operation of the torque command generation unit (target value generation means) of FIG. 3 will be described in accordance with the flowchart of the “target value calculation processing program” for realizing the target value generation means of the present embodiment of FIGS. 4 and 5. explain.
[0037]
  In this target value calculation processing program, first, in step 510, the current time t is stored in a time variable t1 which is a predetermined time saving area. Next, in step 520, the steering angle θ and the vehicle speed V are input from the steering angle sensor 16 and the vehicle speed sensor 15, respectively.
  Next, at step 530, the angular velocity ω of the steering wheel is calculated as a provisional value based on the displacement amount from the steering angle θ of the steering wheel (steering wheel 10) from one input cycle before.
[0038]
  Next, at step 540, the angular velocity ω of the steering wheel is properly determined by the LPF processing unit 402 (detected angular velocity vibration mitigating means). In this LPF (low-pass filter) process, a known or appropriate LPF process is used to remove vibration components in a specific frequency band possessed by the rotational angular velocity of the steering wheel tentatively calculated based on the detected steering angle θ. Thus, the angular velocity ω of the steering wheel is determined.
[0039]
  Next, in step 550, the current time t is stored in a time variable t2 which is a predetermined time saving area. In step 560, an elapsed time Δt from the previous input time t1 of the steering angle θ to the present is calculated.
  In step 570, the steering angle estimation processing unit 403 (steering angle estimation means) calculates an accurate value (estimated value) Θ of the current steering angle according to the following equation (6) based on the input value or the calculation result. To do.
[Formula 6]
  Θ = θ + ωΔt (6)
  Here, the variables θ, ω, and Δt have values obtained in the above steps 520, 540, and 560, respectively.
[0040]
  Further, as the extrapolation process of the formula (6), other known extrapolation methods may be used. That is, in general, as these extrapolation processes, for example, an arbitrary arbitrary approximation such as an n-order approximation (n ≧ 1) or an approximation using an m-order function (m ≧ 1) is used. It is possible to take measures. For example, the values of n and m may be determined in consideration of various trade-off factors such as program development expenses, CPU computing capability, and required rudder angle calculation accuracy. Of course, the situation is the same when other general extrapolation methods are introduced.
[0041]
  In step 580, the rotation direction of the handle is determined by the cutting / returning determination unit 404 (rotation direction determination means). However, this determination process may be executed by sign determination of the angular velocity ω used in the above equation (6).
[0042]
  Further, in step 610 to step 630 (FIG. 5), the reaction force command value calculation unit 405 (basic term generating means) of FIG. 3 is executed.
  That is, first, in step 610, an interpolation process for the vehicle speed V is performed. As a result, a more accurate value (correction value or estimated value) can be used for the vehicle speed V.
  Next, in step 620, for example, a “hysteresis curve used for reaction force command value calculation” as illustrated in FIG. 6 is determined based on the vehicle speed V.
  In the present embodiment, for example, as described above, the target value of the reaction force of the steering wheel accompanying steering, that is, the reaction force command value τ is set to the angular velocity ω of the steering wheel as described in the above-described equation (4). Since it can be determined independently of the value, the design (tuning) of such a hysteresis curve can be carried out more easily than in the prior art.
[0043]
  In step 630, the reaction force command value τ is determined based on the determination result in step 580, the hysteresis curve, and the estimated steering angle Θ obtained in step 403.
  In step 640, the damper gain multiplication unit 406 (damper term generating means) performs a damper torque T based on the angular velocity ω._DDetermine the value of. This damper torque T_DThe value of can be determined, for example, according to the above equation (5) or the like, and can be, for example, a value approximately proportional to the angular velocity ω.
[0044]
  In step 650, the torque command value adding unit 407 determines the target value h according to the above equation (3).
  In step 660, the target value correction processing unit 408 (command value vibration mitigating means) executes a correction process of the target value h based on a predetermined interpolation process or a predetermined extrapolation process, and the robust torque loop of FIG. Output to.
[0045]
  In step 670, the process waits until the next output cycle of the target value h to the robust torque loop of FIG. This output cycle is shorter than the determination cycle (calculation cycle) of the reaction force command value τ.
  In step 680, it is determined whether or not the determination period (calculation period) of the reaction force command value τ has come. If the calculation time has been reached, the process proceeds to step 690; otherwise, the process proceeds to step 660.
[0046]
  In step 690, it is determined whether or not the input period of the steering angle θ has come. If the input timing has been reached, the process proceeds to step 510, and if not, the process proceeds to step 550. Here, ΔT is a constant representing the input period of the steering angle θ.
  For example, the “target value calculation processing program” can be realized by the above processing flow.
[0047]
  FIG. 7 is a graph illustrating a measurement record of the behavior of the handle (steering wheel 10) of the electric power steering apparatus 100 according to the present embodiment. This measurement record is recorded under measurement conditions substantially equivalent to the measurement record in the prior art of FIG.
  From FIG. 7, it can be seen that according to the present invention, the vibration of the handle can be suppressed much more effectively than in the past.
[0048]
  Damper torque T_DAs a calculation method of, it is not always necessary to use a form like the above-mentioned formula (5). That is, damper torque T_DAs the calculation method, a known calculation method used conventionally or any appropriate calculation method can be used.
[0049]
  FIG. 12 is a control block diagram illustrating another control method in another conventional electric power steering apparatus. For example, as seen in this conventional example, in the above-described embodiment of the present invention, instead of using the above-described formula (5), the damper torque T_DThe method of calculating | requiring the value of according to following Formula (7) etc. is applicable.
[Expression 7]
  T_D= E3 (ω, a, V) (7)
  Here, the independent variable a is the acceleration of the vehicle, the independent variable V is the vehicle speed, and the function E3 is an appropriate monovalent function.
  Moreover, the implementation method of each function described above is arbitrary, and is usually configured based on table data constituting a data map (graph).
[0050]
  For example, according to the embodiment of the present invention as described above, the functions and effects of the present invention can be sufficiently obtained.
[Brief description of the drawings]
FIG. 1 is a logical hardware configuration diagram of an electric power steering apparatus 100 according to an embodiment of the present invention.
FIG. 2 is a control block diagram showing a logical outline of a control method of the electric power steering apparatus 100.
FIG. 3 is a control block diagram of target value generation means of the electric power steering apparatus 100.
FIG. 4 is a flowchart (first half) of a “target value calculation processing program” that realizes target value generation means of the electric power steering apparatus 100;
FIG. 5 is a flowchart (second half) of a “target value calculation processing program” that realizes target value generation means of the electric power steering apparatus 100;
6 is a graph illustrating a hysteresis curve used for calculating a reaction force command value of the electric power steering apparatus 100. FIG.
7 is a graph illustrating the behavior of the handle (steering wheel 10) of the electric power steering apparatus 100. FIG.
FIG. 8 is a control block diagram illustrating an outline of a general control method of an electric power steering apparatus using steering torque control means (62) set so as to ensure robustness and stability.
FIG. 9 is a control block diagram of a control method (example 1) of conventional target value generating means (corresponding to 61 in FIG. 8).
10 is a control block diagram of a control method (example 2) of conventional target value generation means (corresponding to 61 in FIG. 8).
11 is a graph illustrating the behavior of a handle of an electric power steering apparatus using conventional target value generation means (control method (example 2) in FIG. 10).
FIG. 12 is a control block diagram illustrating another control method in another conventional electric power steering apparatus.
[Explanation of symbols]
  402... LPF processing unit (detection angular velocity vibration mitigating means)
  403 ... Steering angle estimation processing unit (steering angle estimation means)
  404 ... Increase / return determination unit (rotation direction determination means)
  405 ... Reaction force command value calculation unit (basic term generating means)
  406 ... damper gain multiplier (damper term generating means)
  407 ... Torque command value adder
  408 ... Target value correction processing unit (command value vibration mitigation means)

Claims (6)

A motor for applying auxiliary torque to assist the steering of the vehicle to the steering mechanism, a torque sensor for detecting the steering torque q applied by the driver to the steering wheel, a vehicle speed sensor for detecting the traveling speed (vehicle speed V) of the vehicle, In an electric power steering apparatus having a steering angle sensor for detecting a rotation angle (steering angle θ) of the steering wheel and a motor control device for driving and controlling the motor,
By the steering angle detection value steering angle extrapolation process based on the theta, an estimate Θ of theta said steering angle in the vicinity of the current or current, calculates regular basis in a cycle shorter than the output cycle of the steering angle sensor Rudder angle estimating means;
Generating a target value for calculating the target value h that the steering torque q should reach based on at least the estimated value Θ and at least one variable of the rotational angular velocity ω of the steering wheel or the vehicle speed V Means,
Wherein as the steering torque q to follow the target value h, the electric power steering apparatus characterized by comprising a steering torque control means for determining a command value I _A of the drive current of the motor. A motor for applying auxiliary torque to assist the steering of the vehicle to the steering mechanism, a torque sensor for detecting the steering torque q applied by the driver to the steering wheel, a vehicle speed sensor for detecting the traveling speed (vehicle speed V) of the vehicle, In an electric power steering apparatus having a steering angle sensor for detecting a rotation angle (steering angle θ) of the steering wheel and a motor control device for driving and controlling the motor,
Detected angular velocity vibration mitigating means for removing a vibration component in a specific frequency band of the rotational angular velocity of the steering wheel calculated based on the detected value of the steering angle θ;
Using the rotational angular velocity ω calculated by the detected angular velocity vibration mitigating means, the estimated value Θ of the steering angle θ at or near the present is obtained by the steering angle extrapolation process based on the detected value of the steering angle θ. Rudder angle estimating means for calculating the steering angle approximately periodically with a cycle shorter than the output cycle of the angle sensor;
A target value generating means for calculating a target value h to be reached by the steering torque q based on at least the estimated value Θ;
As the steering torque q to follow the target value h, the steering torque control means for determining a command value I _A of the driving current of said motor,
An electric power steering apparatus comprising: Comprising a detection angular vibration damping hand stage you remove vibration component in a specific frequency band angular velocity of the steering wheel which is calculated based on the detected value of the steering angle θ has,
2. The electric power steering apparatus according to claim 1, wherein the steering angle estimating unit calculates the estimated value Θ based on the rotational angular velocity ω calculated by the detected angular velocity vibration mitigating unit. The target value h, by shortening using a predetermined interpolation / extrapolation the output period of the command value I _A, the target value h, to reduce the amount of change per output cycle of the command value I _A the electric power steering apparatus according to any one of claims 1 to 3, characterized in that it has a that command value vibrational relaxation hand stage. The target value generating means includes
Basic term generating means for generating a basic term that depends on at least the estimated value Θ based on a predetermined hysteresis characteristic;
5. The damper term generating means for generating a damper term depending on at least the rotational angular velocity ω of the steering wheel is provided independently of each other or in parallel with each other. 5. Electric power steering device. The target value generating means, or the steering torque control means,
Using a transfer function set to ensure robust stability against model errors and disturbances in the control model of the electric power steering device,
The electric power steering apparatus according to any one of claims 1 to 5, characterized in that to determine the target value h, and the command value I _A.

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