Technical field
[0001]
　The present invention is the electric power steering apparatus having a control function for receiving the steering angle, together with the estimated steering angle from the 4-wheel wheel speed signal for calculating a steering estimated steering angle, the likelihood of the steering estimated steering angle It was determined from 4-wheel wheel speed, an electric power steering apparatus for preventing unauthorized output control using the steering estimated steering angle by correcting the control output using the steering estimated steering angle or the steering estimated steering angle.
[0002]
　Further, the present invention returns a handle with a steering angle estimated based on the wheel speed to an electric power steering apparatus equipped with (active return) control function.
Background technique
[0003]
　Steering assist force by the rotation force of the motor to a steering mechanism of a vehicle electric power steering apparatus which provides (assist force) (EPS) is the driving force of the motor by the transmission mechanism such as gears or a belt via reduction gear, a steering shaft or adapted to impart a steering assist force to the rack shaft. Such conventional electric power steering apparatus, in order to accurately generate a torque of the steering assist force, and performs a feedback control of a motor current. The feedback control is the difference between a current command value and a motor current detection value to adjust the voltage applied to the motor so as to decrease, the voltage applied to the motor adjustment is generally PWM (pulse width modulation) control of the duty It is carried out in the adjustment.
[0004]
　Explaining shows the general construction of an electric power steering apparatus in FIG. 1, the handle (steering wheel) 1 of column shaft (steering shaft, the steering wheel shaft) 2 is a reduction gear 3, universal joints 4a and 4b, a pinion rack mechanism 5 , via tie rods 6a, the 6b, which is further connected steered wheels 8L, the 8R via the hub unit 7a, 7b. In addition, the column shaft 2 is interposed torsion bar, the steering angle sensor 14 for detecting a steering angle of the steering wheel 1 theta by torsional angle of the torsion bar, and a torque sensor 10 is provided for detecting the steering torque Th , motor 20 for assisting the steering force of the steering wheel 1 is connected to the column shaft 2 via the reduction gear 3. The control unit (ECU) 30 for controlling the electric power steering apparatus, the electric power from the battery 13 is supplied, the ignition key signal is inputted through the ignition key 11. Control unit 30 performs the calculation of the assist (steering assist) command current command value based on the vehicle speed Vel detected by the steering torque Th and the vehicle speed sensor 12 detected by the torque sensor 10, compensation for the current command value controlling the current supplied to the motor 20 by the voltage control value Vref subjected to. Incidentally, the vehicle speed Vel is also possible to receive from such CAN (Controller Area Network).
[0005]
　Incidentally, the steering angle sensor 14 is not mandatory and may not be disposed, it is also possible to obtain the steering angle from the rotation sensor, such as a concatenated resolver to the motor 20.
[0006]
　The control unit 30 is connected with a CAN (Controller Area Network) 40 for exchanging various kinds of information of the vehicle, the vehicle speed Vel is also possible to receive from CAN40. Further, the control unit 30, communications other than CAN40, an analog / digital signal, even non CAN41 for exchanging radio waves connectable.
[0007]
　It consists of a control unit 30 mainly CPU (including also MPU or MCU, etc.), is shown in Figure 2 when showing the general functions performed by the program in the CPU.
[0008]
　To explain the function and operation of the control unit 30 with reference to FIG. 2, the vehicle speed Vel from the steering torque Th and the vehicle speed sensor 12 (or CAN40) detected by the torque sensor 10 is inputted to the current command value calculating section 31, current command value calculating section 31 calculates a current command value Iref1 to parameters vehicle speed Vel using the assist map. The calculated current command value Iref1 is an upper limit value by the current limiting unit 33, the limited current command value Iref2 is input into the subtraction unit 33. Subtraction unit 34, the deviation Iref3 seek (= Iref2-Im) between the motor current Im is fed back and the current command value Iref2, deviation Iref3 is subjected to PI control or the like by the current controller 35, a voltage control value Vref is inputted to the PWM controller 36 is calculating the duty, to PWM drive the motor 20 through the inverter 37. Motor current Im of the motor 20 is detected by a motor current detector 38 and fed back to the subtraction section 34.
[0009]
　Compared to conventional hydraulic power steering system, such an electric power steering apparatus The mounting of the motor and the gear, friction is large, steering wheel return after bent in an intersection is poor. To improve the steering wheel return at intersections, as shown in Japanese Patent No. 3551147 (Patent Document 1), control for returning the steering wheel based on the steering angle by using the steering angle sensor has become widespread. That is, FIG. 3 shows a schematic configuration of a device described in Patent Document 1, a steering angle theta, steering wheel return control unit 32 calculates the steering wheel return current HR based on a steering angular velocity ω and the vehicle speed Vel is provided , so that the computed steering wheel return current HR adds the current command value Iref1 in the addition unit 32A, and inputs a current command value Iref4 corrected by the current HR returned handle to the current limiting unit 33. However, in the apparatus of Patent Document 1 because the cost by the steering angle sensor mounting, steering wheel return control is desired not require steering angle sensor.
[0010]
　Therefore, rather than the steering angle sensor, an electric power steering apparatus has been proposed which is adapted to steering wheel return control by using the wheel speed (Patent No. 3525541 (Patent Document 2)). However, in the electric power steering apparatus described in Patent Document 2, for performing the steering wheel return control based on the steering angle estimated from the left and right wheel speed signals, the steering angle when the vehicle slip occurs in snow or the like and erroneous estimation, there is a problem such as the handle will move in an unintended direction by the driver.
[0011]
　Furthermore, by comparing the steering angle and the steering angle sensor value estimated from the rear wheel left and right wheel speed signals, if the difference is the threshold abnormality, reducing the control output of the control using the estimated steering angle (an incorrect output prevention) electric power steering apparatus has been known (Japanese Patent No. 4671435 (Patent Document 3)). However, in the apparatus described in Patent Document 3, since it requires the steering angle sensor, there is a problem that cost is caused.
CITATION
Patent Literature
[0012]
Patent Document 1: JP Patent No. 3551147
Patent Document 2: JP Patent No. 3525541
Patent Document 3: JP Patent No. 4671435
Summary of the Invention
Problems that the Invention is to Solve
[0013]
　The present invention has been made in view of the above described circumstances, an object of the present invention calculates the wheel estimated steering angle from the front left and right wheel speed, calculates a rear-wheel estimated steering angle from the rear left wheel speed, front wheel calculates a 4-wheel estimated steering angle by using the rear wheel estimated steering angle and the estimated steering angle, the front wheel estimated steering angle and the rear wheel estimated steering angle, corrects the likelihood of a four-wheel estimated steering angle by using the four-wheel wheel speed or by correcting the output of the control using the four-wheel estimated steering angle, without the need for a rudder angle sensor, and to provide a high-performance electric power steering apparatus for preventing unauthorized output.
Means for Solving the Problems
[0014]
　The present invention includes a steering torque sensor for detecting steering torque input to the steering mechanism, motor for applying a current command value calculation unit for calculating a current command value based on at least the steering torque, the assist torque to the steering mechanism When relates to an electric power steering apparatus that includes a motor drive control unit for driving and controlling the motor based on the current command value, the object of the present invention is provided with a control function which receives the steering angle, 4-wheel wheel calculating a front wheel estimated steering angle and the rear wheel estimated steering angle from the fast, includes a steering angle estimation calculation section for calculating a four-wheel estimated steering angle by using the front wheel estimated steering angle and the rear wheel estimated steering angle, the four-wheel the estimated steering angle is achieved by using the steering angle control.
[0015]
　The above-described object of the present invention, the four-wheel wheel speed, the front wheel estimated steering angle and based on the rear wheel estimated steering angle, the four-wheel estimated steering angle or the output of the control using the four-wheel estimated steering angle by that correction gain calculation unit is further provided for calculating a correction gain for correcting the or the correction gain calculation unit, and outputs a vehicle slip gain based on the front wheel estimated steering angle and the rear wheel estimated steering angle and the vehicle slip determination unit, the four-wheel and driven wheel slip determination unit for outputting a driving wheel slip gain based on the wheel speed, the vehicle slip gain and the driving wheel slip gain multiplication unit which outputs the correction gain by multiplying the by being constituted by a, or the vehicle slip determination unit, determine a gradual change amount for a vehicle slip gain depending on the absolute value of the difference between the front wheel estimated steering angle and the rear wheel estimated steering angle And, by the which the vehicle slip gain for gradual change gradually changing to so as to output the vehicle slip gain, or by the vehicle slip gain for gradual change is made to vary in accordance with the vehicle speed , or the driving wheel slip determination unit determines the gradual change amount for the driving wheel slip gain depending on the absolute value of the difference between the front wheel speed and rear wheel speed based on the four-wheel wheel speed, the driving wheel slip gain by and outputs a gradual change to the driving wheel slip gain in gradual change, or the steering angle estimation calculation section, the front wheel estimated steering angle and the in accordance with the vehicle speed or the steering angular speed or the steering torque by being provided with a weighting unit for calculating by changing the weighting of the rear wheel estimated steering angle, or the weighting unit, the vehicle speed or the steering angular velocity or the steering A sensitive table for outputting front wheel weight X and the rear wheel weights Y in response to the torque, a first multiplying unit for multiplying the front wheel estimated steering angle and the front wheel weights X, the rear wheel estimated steering angle and the rear wheel weight Y by being configured in a second multiplying unit for multiplying a first multiplication unit and the adding unit which outputs the 4-wheel estimated steering angle by adding the multiplication results of the second multiplier unit, more effective It is achieved.
[0016]
　Furthermore, the present invention is applied steering torque sensor for detecting steering torque input to the steering mechanism, a current command value calculation unit for calculating a current command value based on at least the steering torque, the assist torque to the steering mechanism motor and relates to an electric power steering apparatus that includes a motor drive control unit for driving and controlling the motor based on the current command value, the object is the front wheel estimated steering angle and the rear wheel than four wheels wheel speed of the present invention that calculates an estimated steering angle, the front wheel estimated steering angle and the steering angle estimation calculation section for calculating a four-wheel estimated steering angle with the rear wheel estimated steering angle, the four-wheel wheel speed, the front wheel estimated steering angle and the a correction gain calculator for calculating a correction gain for correcting the incorrect output based on the rear wheel estimated steering angle, the four-wheel wheel speed, the correction gain, on the basis of the vehicle speed and the motor angular velocity estimate And a steering wheel return control unit calculates the bundle return control value is achieved by correcting the current command value by the steering wheel return control value.
Effect of the invention
[0017]
　According to the electric power steering apparatus according to the present invention, from the front left and right wheel speed, calculates a front wheel estimated steering angle, than the rear wheel left and right wheel speed, calculates a rear-wheel estimated steering angle, the front wheel estimated steering angle and the rear wheel estimation calculates a 4-wheel estimated steering angle by using the steering angle, the front wheel estimated steering angle and the rear wheel estimated steering angle, the correction or 4-wheel estimated steering angle the likelihood of a four-wheel estimated steering angle by using the four-wheel wheel speed and it corrects the output of the control using.
[0018]
　Thus, without requiring a steering angle sensor, an inexpensive configuration, it is possible to prevent unauthorized output, high reliability can be provided an electric power steering apparatus.
BRIEF DESCRIPTION OF THE DRAWINGS
[0019]
Is a block diagram showing an outline of FIG. 1 the electric power steering system.
Is a block diagram showing a configuration example of a control system of FIG. 2 the electric power steering apparatus.
It is a block diagram illustrating an example of a control system of an electric power steering apparatus having the FIG. 3 conventional handle return control function.
Is a block diagram showing a configuration example of FIG. 4 the present invention.
5 is a block diagram showing a configuration example of a steering angle estimating portion.
6 is a diagram for explaining the estimation of the 4-wheel estimated steering angle.
7 is a schematic view for explaining a steering angle estimating.
8 is a block diagram showing a configuration example of a weighting section of the steering angle estimation calculation unit.
9 is a block diagram showing a configuration example of a correction gain calculation unit.
FIG. 10 is a schematic diagram for explaining the operation of the vehicle slip determination unit.
11 is a block diagram showing a configuration example of a vehicle slip determination unit.
It is a characteristic diagram showing an operation example of FIG. 12 vehicle slip determination.
13 is a schematic view for explaining the operation of the drive wheel slip judging portion.
14 is a block diagram showing a configuration example of a driving wheel slip judging portion.
It is a block diagram showing a configuration example of FIG. 15 the restoration controller.
16 is a characteristic diagram showing an example of a steering angle sensitive table.
17 is a characteristic diagram showing an example of a vehicle speed sensitive table.
18 is a characteristic diagram showing an example of the steering angular velocity sensing table.
Is a flowchart showing an operation example of FIG. 19 the present invention.
Is a flowchart showing an operation example of FIG. 20 steering angle estimating arithmetic unit.
21 is a flowchart showing an operation example of the correction gain calculation unit.
Is a flowchart showing an operation example of FIG. 22 the restoration controller.
DESCRIPTION OF THE INVENTION
[0020]
　The present invention calculates the wheel estimated steering angle from the front left and right wheel speeds, the rear wheels to calculate the rear wheel estimated steering angle from the right and left wheel speeds, four-wheel estimated steering angle by using the rear wheel estimated steering angle and the front wheel estimated steering angle calculates the front wheel estimated steering angle and the rear wheel estimated steering angle, by correcting the output of the correction or control using the four-wheel estimated steering angle the likelihood of a four-wheel estimated steering angle by using the four-wheel wheel speed , without requiring a steering angle sensor, so as to prevent incorrect output.
[0021]
　Further, return handle the above configuration is applied to the (active return) control.
[0022]
　Hereinafter, the embodiments of the present invention will be described in detail with reference to the accompanying drawings. In the following embodiments, an example of application to handle return control of the present invention.
[0023]
　Figure 4 shows in an example of the configuration of the present invention in association with FIG. 3, the vehicle speed Vel, 4-wheel wheel speed (front left and right wheel speed, rear left and right wheel speed) type and Vw and the motor angular velocity estimate .omega.m, 4 a steering angle estimating portion 100 for calculating the wheel estimated steering angle θest and correction gain CG, vehicle speed Vel, the motor angular velocity estimate .omega.m, enter the four-wheel estimated steering angle θest and correction gain CG, calculates the steering wheel return control value HRC a steering wheel return control unit 150 outputs Te, and the adding unit 160 to correct by adding the steering wheel return control value HRC on the current command value Iref1 is provided.
[0024]
　Steering angle estimating portion 100 as shown in FIG. 5, enter the vehicle speed Vel, 4-wheel wheel speed Vw and the motor angular velocity estimate .omega.m, 4-wheel estimated steering angle? Est, front wheel estimated steering angle θf and rear estimated steering angle θr the type steering angle estimating arithmetic unit 110 which calculates and outputs, four-wheel wheel speed Vw, the wheel estimated steering angle θf and rear estimated steering angle [theta] r, composed of a correction gain calculator 120 for calculating a correction gain CG It is.
[0025]
　Steering angle estimating arithmetic unit 110 FIG. 6 (A), (B), as shown in (C), the front wheel estimated steering angle θf than relation of the front wheel speed and steering angle theta, the rear wheel speed and steering angle seek the rear wheel estimated steering angle θr than relational expression of θ.
[0026]
　Steering angle estimating wheel by the arithmetic unit 110 from the 4-wheel wheel speed Vw estimated steering angle θf and the rear wheel estimated steering angle [theta] r, calculates a four-wheel estimated steering angle θest but the front wheel estimated steering angle θf and the rear wheel estimated steering angle [theta] r for the calculation, a known method such as disclosed in Japanese Patent No. 4167959. As shown in FIG. 7, four wheels fl, fr, rl, Rfl each turning radius of rr, Rfr, Rrl, and Rrr, the front wheels fl, .alpha.l fr steering angle, respectively, and .alpha.r, an axle distance of the vehicle L and then, a car width and E. Further, the front wheel axle center of the turning radius and Rf, the rear wheel axle center of the turning radius is Rr. Each wheel fl, fr, rl, wheel speed of rr Omegafl the left front wheel as (wheel angular velocity),? FR of the front right wheel, rl a left rear wheel and the right rear wheel and rr, and α the steering angle of the vehicle body center the wheel speeds ωfl, ωfr, ωrl, ωrr has the relationship shown in the following equation (1) and (2).
[0027]
[Number 1]

[0028]
[Number 2]

　Note that the four-wheel estimated steering angle? Est, by using the average value of the front wheel estimated steering angle θf and the rear wheel estimated steering angle θr as the following equation 3, robustness to estimation errors due to wheel speed disturbance it can be increased.
[0029]
[Equation 3]

　or in addition to the above average value, 4-wheel estimated steering angle θest changes the wheel weight Y after the front wheel estimated steering angle θf of the front wheel weight X and the rear wheel estimated steering angle θr in accordance with the vehicle speed Vel, it is also possible to calculate a weighted average value of the front wheel estimated steering angle θf and rear estimated steering angle [theta] r. The formula in this case is the following equation (4).
[0030]
[Expression 4]

　The wheel weights Y after the front wheel estimated steering angle θf of the front wheel weight X and the rear wheel estimated steering angle [theta] r, the weighting unit of the structure of the steering angle estimation calculation section 110 of the case of changing each in accordance with the vehicle speed Vel , for example, as shown in FIG. That is, wheel weights Y after the front wheel weight X and the rear wheel estimated steering angle of the front wheels estimated steering angle from the vehicle speed sensitive table 111 by responding to the vehicle speed Vel is output with a relationship "X + Y = 1.0". Wheel weights Y of the rear-wheel estimated steering angle is multiplied by the rear-wheel estimated steering angle θr in the multiplication section 112, a front wheel weight X of the front wheel estimated steering angle is multiplied by the front-wheel estimated steering angle θf by multiplying unit 113. Each multiplication result of the multiplication unit 112 and 113 are added by an adder 114, the added value is output as a 4-wheel estimated steering angle? Est.
[0031]
　Vehicle speed sensitive table 111, for example, because the vehicle speed is low is set as X = 0.8, Y = 0.2, the front wheel is a half slip state during turning traveling at high speed, the estimation accuracy is lowered, X = 0 .2, increasing wheel weight Y of the rear-wheel estimated steering angle θr as Y = 0.8.
[0032]
　Incidentally, the front wheel weight X and the rear wheel weights Y in FIG. 8 has changed linearly, or may be changed nonlinearly. Further, although changing the wheel weight X and the rear wheel weight Y on the basis of the vehicle speed in FIG. 8, it may be varied in accordance with the steering angular velocity and the steering torque.
[0033]
　Correction gain calculator 120 determines the vehicle slip, and the driving wheel slip by using the front wheel estimated steering angle .theta.f, rear estimated steering angle θr and the four-wheel wheel speed Vw, corrects the likelihood of a four-wheel estimated steering angle θest Therefore, to calculate the correction gain CG. Correction gain calculator, as shown in FIG. 9, is constituted by the vehicle slip determination portion 121 and the driving wheel slip determining section 122, the vehicle slip gain WSG and driving wheel slip gain DWG calculated from each multiplied by the multiplication unit 123 performs an operation for outputting the multiplication result as a correction gain CG.
[0034]
　Vehicle slip determination unit 121, next to the front wheel estimated steering angle .theta.f ≒ rear wheel estimated steering angle θr as during grip-driving is shown in FIG. 10 (A), the vehicle is in a slip state, the four-wheel as shown in FIG. 10 (B) either the wheel speed slips, with the characteristic difference and rear wheel estimated steering angle θr front wheel estimated steering angle .theta.f ≠ occurs, determines the vehicle slip. The vehicle slip determination unit 121 as shown in FIG. 11, the front wheel estimated steering angle θf and the rear wheel estimated steering angle θr absolute vehicle slip gain for gradual change in gradual change calculation unit 121-1 in response to VHJ difference It is calculated, to increase or decrease the vehicle slip gain WSG via output restricted integration unit 121-2 a gradual change VHJ vehicle slip gain. If the difference between the front wheel estimated steering angle θf and the rear wheel estimated steering angle θr is large rapidly reduce the vehicle slip gain WSG, gradually vehicle slip when the difference between the front wheel estimated steering angle θf and the rear wheel estimated steering angle θr is small increase the gain WSG.
[0035]
　Calculating the vehicle slip gain WSG is, when the vehicle slip curve road snow (state difference of the front wheel estimated steering angle θf and the rear wheel estimated steering angle θr is larger) sharply reduces the vehicle slip gain WSG, a straight line running, if it becomes the gripping state (the difference is small state of the front wheel estimated steering angle θf and the rear wheel estimated steering angle [theta] r), is characterized by gradually increasing the vehicle slip gain WSG.
[0036]
　Further, gradual change amount for a vehicle slip gain, as shown in FIG. 12, is changed according to the vehicle speed. Since the slip in the low-speed hardly occurs, | front wheel estimated steering angle θf- rear estimated steering angle [theta] r | a threshold value to be compared with the larger, because the slip is likely to occur at high speed, | front wheel estimated steering angle θf- rear wheels estimate to reduce the threshold to be compared with the | steering angle θr. The settings are changed by a control function that uses the four-wheel estimated steering angle. The fast | possibly to increase the threshold value to be compared with | front wheel estimated steering angle θf- rear estimated steering angle [theta] r.
[0037]
　On the other hand, the driving wheel slip determining section 122, the drive wheels grip-driving front wheel speed Wf ≒ rear wheel speed Wr becomes as shown in FIG. 13 (A) when, in the driving wheel slip state, shown in FIG. 13 (B) as slip drive wheels such as front or rear wheel, determines a driving wheel slip by using the characteristic difference is generated as the front wheel speed Wf ≠ rear wheel speed Wr. Front left and right wheel speeds WFL and WFR, from the relationship between the rear wheel left and right wheel speed WRL and WRR, front wheel speed Wf is the following equation (5), the rear wheel speed Wr can be determined by the following Expression 6.
[0038]
[Formula 5]

[0039]
[6]

　The driving wheel slip determining section 122 as shown in FIG. 14, the driving wheel slip gain for gradual change in gradual change calculation unit 122-1 in response to the difference between the front wheel speed Wf and the rear wheel speed Wr calculating a VHD, increases or decreases the driving wheel slip gain DWG via output restricted integration unit 122-2 a gradual change VHD for driving wheel slip gain. If the difference between the front wheel speed Wf and the rear wheel speed Wr is large reduces sharply driving wheel slip gain DWG, when the difference between the front wheel speed Wf and the rear wheel speed Wr is smaller gradually driving wheel slip gain DWG increase.
[0040]
　Calculation of the driving wheel slip gain DWG, when the vehicle is suddenly started at snow (state difference front wheel speed Wf and the rear wheel speed Wr is large), rapidly reduces the driving wheel slip gain DWG, grip state (the difference of the front wheel speed Wf and the rear wheel speed Wr is small) causes gradually increasing the driving wheel slip gain DWG.
[0041]
　Vehicle slip gain WSG, the driving wheel slip gain DWG both constant setting, it is possible to adjust the rapid change-gradual change in the gain, with 4-wheel estimated steering angle θest and 4-wheel estimated steering angle θest possible to adjust the responsiveness of the time for correcting the control output becomes.
[0042]
　The restoration controller 150, from the correction gain CG 4-wheel estimated steering angle? Est, steering wheel return as well as calculating the (active return) control values ​​HRC, when the vehicle slips and the drive wheels slip back handle (active return) control values ​​HRC to restrict. For calculating the steering wheel return control value HRC based on the four-wheel estimated steering angle? Est, when the vehicle slips or the drive wheel slip, the incorrect output unintended steering wheel return control value HRC by erroneous estimated four-wheel estimated steering angle? Est. Vehicle slip or driving wheel slip upon occurrence decreases the correction gain CG, it is possible to limit the unauthorized output.
[0043]
　Configuration Example of a steering wheel return control unit 150 is a 15, 4-wheel estimated steering angle θest is inputted to the steering angle response table 151 having the characteristics shown in FIG. 16, the steering angle output from the steering angle response table 151 θ1 is inputted to the multiplier 154. Characteristics of the steering angle response table 151, as shown in FIG. 16, with respect to the absolute value of the 4-wheel estimated steering angle? Est, gradually increases from the four-wheel estimated steering angle Shitaesta, peaked at 4-wheel estimated steering angle .theta.m, thereafter gradually decreases, becomes zero in the four-wheel estimated steering angle θestb later. Further, the vehicle speed Vel is inputted to the vehicle speed sensitive table 152 having the characteristics shown in FIG. 17, the output Vel1 the vehicle speed sensitive table 152 is input to the multiplier 154, the motor angular velocity estimate ωm is characteristic as shown in FIG. 18 is inputted to the steering angular velocity sensitive table 153 having an output ωm1 steering angular velocity sensitive table 153 is input to the multiplier 155.
[0044]
　Vehicle speed sensitive table 152 as shown in FIG. 17, for example abruptly nonlinear increase from a slow speed Vela, since a predetermined peak is a characteristic to decrease gradually. Further, the steering angular velocity sensing table 153 as shown in FIG. 18, with respect to the absolute value of the motor angular velocity estimate .omega.m, has a property of gradually nonlinear increase from the motor angular velocity estimate Omegama.
[0045]
　Multiplying unit In 154 outputs θ1 and Vel1 are multiplied, the multiplication result θ2 is input to the multiplier 155 is multiplied by the output ωm1 the multiplication unit 155, basic control value HRa a multiplication result is input to the multiplier 156 It is multiplied by the correction gain CG Te. Basic control value HRb obtained in the multiplication unit 156 is input to the output restriction processing unit 157 for performing an output restriction of the maximum value, the output limited steering wheel return control value HRC is output.
[0046]
　In such a configuration, first, the entire operation example will be described with reference to the configuration example of the flow chart and FIG. 4 of FIG. 19.
[0047]
　A steering angle estimating portion 100, a vehicle speed Vel is inputted (step S1), 4-wheel wheel speed Vw is input (step S2), the motor angular velocity estimate ωm is inputted (step S3). The order of these inputs may be changed as appropriate. Steering angle estimating portion 100, based on the input vehicle speed Vel, 4-wheel wheel speed Vw and the motor angular velocity estimate .omega.m, while calculating the front wheel estimated steering angle θf and rear estimated steering angle [theta] r, 4-wheel estimated steering angle It calculates and outputs a? est (step S10). Steering angle estimating portion 100 also calculates and outputs the correction gain CG (step S30). 4-wheel estimated steering angle? Est and correction gain CG is inputted to the handle return control unit 150, steering wheel return control unit 150 calculates the steering wheel return control value based on the four-wheel estimated steering angle? Est (step S50), correction gain CG handle return corrects the control value based on (step S70). Steering wheel return control value HRC is added to the current command value Iref1 in the addition unit 160.
[0048]
　Then, the steering angle estimation calculation section 110, an operation example of the weighting unit to apply the front wheel weight X and the rear wheel weight Y on the front and rear wheels estimated steering angle θf and [theta] r, with reference to the configuration example of the flow chart and Figure 8 in FIG. 20 It described Te.
[0049]
　Steering angle estimating the arithmetic unit 110 first front wheel estimated steering angle θf is calculated (step S11), and the rear wheel estimated steering angle θr is calculated (step S12). This order may be reversed. The weighting unit of the vehicle speed sensitive table 111 vehicle speed Vel is inputted (step S13), and vehicle speed sensitive table 111 calculates the front wheel weight X corresponding to the vehicle speed Vel (step S14), and calculates the rear wheel weight Y (step S15). Wheel weights X is input to the multiplier 113 is multiplied by the front-wheel estimated steering angle .theta.f (step S16), and the multiplication result .theta.f · X is added to the adder 114. The rear wheel weights Y is input to the multiplier 112 is multiplied by the rear-wheel estimated steering angle [theta] r (step S17), the multiplication result [theta] r · Y is added to the adder 114. Adding the adding unit 114 multiplication results .theta.f · X and [theta] r · Y, and outputs a 4-wheel estimated steering angle θest is the addition result (Step S18).
[0050]
　The calculation order of the front-wheel weight X and the rear wheel weight Y, is multiplied order in multipliers 112 and 113 can be appropriately changed.
[0051]
　Next, an operation example of the correction gain calculator 110, the flowchart and 9 of FIG. 21, FIG. 11 will be described with reference to the configuration example of FIG. 14.
[0052]
　The vehicle slip determination unit 121 in the correction gain calculator 120 together with the front wheel estimated steering angle θf is input (step S31), a rear wheel estimated steering angle θr is input (step S32). The vehicle slip determination unit 121 gradual change calculation unit 121-1 calculates the vehicle slip gain for gradual change VHJ corresponding to the absolute value of the difference between the front wheel estimated steering angle θf and the rear wheel estimated steering angle [theta] r (step S33), performing integration processing restricted output restricted integrating unit 121-2 outputs the vehicle slip gain WSG (step S34).
[0053]
　Correction is input four-wheel wheel speed Vw to the drive wheel slip determination portion 122 of the gain calculation unit 120 (step S40), together with the front wheel speed Wf is calculated based on the four-wheel wheel speed Vw (step S41), rear wheel speed Wr is calculated (step S42). In the driving wheel slip determining section 122 gradual change calculation unit 122-1 calculates the driving wheel slip gain for gradual change VHD corresponding to the absolute value of the difference between the front wheel speed Wf and the rear wheel speed Wr (step S43), performing integration processing restricted output restricted integrating unit 122-2 outputs a driving wheel slip gain DWG (step S44).
[0054]
　Vehicle slip gain WSG and driving wheel slip gain DWG is input to the multiplier 123, and outputs the multiplication result of the multiplier 123 as the correction gain CG (step S45).
[0055]
　Next, an operation example of the steering wheel return control unit 150 will be described with reference to the configuration example of the flow chart and FIG. 15 in FIG. 22.
[0056]
　First 4-wheel estimated steering angle? Est is inputted to the steering angle response table 151 (step S51), the steering angle response table 151 outputs a steering angle θ1 corresponding to the four-wheel estimated steering angle? Est (step S52). Further, the vehicle speed Vel is inputted to the vehicle speed sensitive table 152 (step S53), vehicle speed sensitive table 152 outputs an output Vel1 corresponding to the vehicle speed Vel (step S54), it is multiplied by the steering angle θ1 in the multiplication unit 154 (Step S55). Further, the motor angular velocity estimate .omega.m is inputted to the steering angular velocity sensing table 153 (step S56), the steering angular velocity sensing table 153 outputs an angular velocity ωm1 corresponding to the motor angular velocity estimate .omega.m (step S57). Angular ωm1 is input to the multiplier 155, the multiplication result θ2 and are multiplied (step S58) of the multiplying unit 154, a multiplication result basic control value HRa is input to the multiplier 156.
[0057]
　Thereafter, calculated by the correction gain calculation unit 120 correction gain CG is inputted to the multiplication unit 156 (step S60), it is multiplied by the basic control value HRa (step S61). Is a multiplication result of the multiplying unit 156 basic control value HRb is input to the output restriction processing unit 157 outputs a steering wheel return control value HRC is limited to a maximum value (step S62), the steering wheel return control value HRC is adding unit is input to the 160.
[0058]
　In the above description has been described by way of handle return (active return) control as an example, lane keep assist, active corner directing light toward the steering angle to prevent other control (lane departure using a four-wheel estimated steering angle lamp can also be applied to, etc.).
DESCRIPTION OF SYMBOLS
[0059]
1 handle (steering
wheel) 2 column shaft (steering shaft, the handle
shaft) 10 torque sensor
12 vehicle speed sensor
13 battery
20 motor
31 current command value calculating unit
32 steering wheel return control unit
33 the current limiting unit
35 current controller
36 PWM controller
37 inverter
100 steering angle estimating portion
110 steering angle estimating arithmetic unit
111 vehicle speed sensitive table
120 correction gain calculator
121 vehicle slip determination unit
122 driven wheel slip determination unit
150 returns the handle (active return) controller
151 steering angle response table
152 vehicle speed sensitive table
153 steering angular velocity-sensitive table

The scope of the claims
[Claim 1]
A steering torque sensor for detecting steering torque input to the steering mechanism, a motor for applying a current command value calculation unit for calculating a current command value based on at least the steering torque, the assist torque to the steering mechanism, the current the electric power steering apparatus that includes a motor drive control unit for driving and controlling the motor based on the command value,
a control function for receiving the steering angle, the front wheel estimated steering angle and the rear wheel estimated steering than four wheels wheel speed calculating the square, with the front wheel estimated steering angle and the steering angle estimation calculation section for calculating a four-wheel estimated steering angle with the rear wheel estimated steering angle, using the four-wheel estimated steering angle to the steering angle control possible an electric power steering apparatus according to claim.
[Claim 2]
The four-wheel wheel speed, on the basis of the front wheel estimated steering angle and the rear wheel estimated steering angle, correction which calculates a correction gain for correcting the output of the four-wheel estimated steering angle or control using the four-wheel estimated steering angle the electric power steering apparatus according to claim 1, gain calculation section is further provided.
[Claim 3]
The correction gain calculation unit,
and outputs a vehicle slip determination unit that outputs a vehicle slip gain based on the front wheel estimated steering angle and the rear wheel estimated steering angle, a driving wheel slip gain based on the four-wheel wheel speed drive a wheel slip determination unit, the vehicle slip gain and an electric power steering apparatus according to claim 2, which is constituted by a multiplication unit for outputting the correction gain by multiplying the driving wheel slip gain.
[Claim 4]
The vehicle slip determination unit,
said determining the gradual change amount for a vehicle slip gain depending on the absolute value of the difference between the front wheel estimated steering angle and the rear wheel estimated steering angle, the vehicle slip gain for gradual change gradually changing to the electric power steering apparatus according to claim 3 and outputs a vehicle slip gain.
[Claim 5]
The electric power steering apparatus according to claim 4, wherein the has a gradual change vehicle slip gain to vary according to the vehicle speed.
[Claim 6]
The driving wheel slip determination unit
determines the gradual change amount for the driving wheel slip gain depending on the absolute value of the difference between the front wheel speed and rear wheel speed based on the four-wheel wheel speed, the driving wheel slip gain for gradual change in gradually changing to an electric power steering apparatus according to any one of claims 3 to 5 and outputs the driving wheel slip gain.
[Claim 7]
The steering angle estimating arithmetic unit,
a vehicle speed or the steering angular velocity or 1 to claim and comprising a weighting unit for calculating by changing the weighting of the front wheel estimated steering angle and the rear wheel estimated steering angle according to the steering torque the electric power steering apparatus according to any one of 6.
[8.]
Said weighting unit,
the vehicle speed or the steering angular velocity or the and sensitive table for outputting front wheel weight X and the rear wheel weights Y in accordance with the steering torque, a first multiplying unit for multiplying the front wheel estimated steering angle and the front wheel weights X When outputs a second multiplication section for multiplying the rear wheel estimated steering angle and the rear wheel weight Y, the four-wheel estimated steering angle by adding the multiplication results of the first multiplication portion and a second multiplier unit the electric power steering apparatus according to claim 7, which is constituted by an adder.
[Claim 9]
A steering torque sensor for detecting steering torque input to the steering mechanism, a motor for applying a current command value calculation unit for calculating a current command value based on at least the steering torque, the assist torque to the steering mechanism, the current the electric power steering apparatus that includes a motor drive control unit for driving and controlling the motor based on the command value,
to calculate a front wheel estimated steering angle and the rear wheel estimated steering angle from the 4-wheel wheel speed, the front wheel estimated steering angle and and the steering angle estimation calculation section for calculating a four-wheel estimated steering angle with the rear wheel estimated steering angle,
the four-wheel wheel speed, correcting the incorrect output based on the front wheel estimated steering angle and the rear wheel estimated steering angle a correction gain calculator for calculating a correction gain,
the four-wheel wheel speed, the correction gain, hand for calculating the steering wheel return control value based on the vehicle speed and the motor angular velocity estimate And Le return control unit,
equipped with electric power steering apparatus characterized by correcting the current command value by the steering wheel return control value.
[Claim 10]
The correction gain calculation unit,
and outputs a vehicle slip determination unit that outputs a vehicle slip gain based on the front wheel estimated steering angle and the rear wheel estimated steering angle, a driving wheel slip gain based on the four-wheel wheel speed drive a wheel slip determination unit, the vehicle slip gain and an electric power steering apparatus according to claim 9, which is constituted by a multiplication unit for outputting the correction gain by multiplying the driving wheel slip gain.
[Claim 11]
The steering angle estimation calculation section,
the vehicle speed or the steering angular velocity or the claims in accordance with the steering torque that comprises a weighting unit for calculating by changing the weighting of the front wheel estimated steering angle and the rear wheel estimated steering angle claim 9 or an electric power steering apparatus according to 10.