[0001]The present invention is not provided with a steering angle sensor, an electric power steering apparatus having a control function for receiving the steering angle, in accordance with the running state of the vehicle by estimating the steering angle from the 4-wheel wheel speed signal steering use to calculate an estimated steering angle, determining the likelihood of the steering estimated steering angle from the four wheels wheel speed, by correcting the control output or a steering estimated steering angle using the steering estimated steering angle, the steering estimated steering angle an electric power steering apparatus for preventing unauthorized output of control had.
[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 control the steering wheel return with 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)).
CITATION
Patent Document
[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]
　However, in the apparatus described in Patent Document 3, since it requires the steering angle sensor, there is a problem that cost is caused.
[0014]
　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 estimated steering angle, with the rear wheel estimated steering angle and the vehicle speed, or the front wheel estimated steering angle, the rear wheels estimated steering angle, vehicle speed and driving conditions (deceleration traveling, such rough road) 4-wheel estimated steering angle by using the and calculates, by correcting the output of the control using a correction or 4-wheel estimated steering angle the likelihood of a four-wheel estimated steering angle by using front wheel estimated steering angle and the rear wheel estimated steering angle, the four-wheel wheel speed, without requiring a steering angle sensor, it is to provide a high-performance electric power steering apparatus for preventing unauthorized output.
Means for Solving the Problems
[0015]
　The present invention includes a torque sensor for detecting steering torque input to a steering mechanism of a vehicle, a current command value calculation unit for calculating a current command value based on at least the steering torque, the steering assist torque to be applied to the steering mechanism a motor for generating relates to an electric power steering apparatus that includes a motor control unit for driving and controlling the motor based on the current command value, the object of the present invention, the front wheel estimated steering angle in accordance with the traveling state of the vehicle of the wheel weights Y is changed after the front wheel weight X and the rear wheel estimated steering angle, steering angle estimating for calculating a four-wheel estimated steering angle based on the front wheel weight X and the rear wheel weight Y (X + Y = 1.0) It is accomplished due to the provision of the arithmetic unit.
[0016]
　The above-described object of the present invention, the traveling state of the vehicle is the acceleration and deceleration traveling, the acceleration and deceleration calculation unit for calculating an acceleration estimate from the vehicle speed, the front wheel weight X and on the basis of the said acceleration estimate by being provided with the acceleration and deceleration sensitive table for calculating a rear wheel weight Y, or the acceleration and deceleration calculation unit, from the memory unit and the current value holds the past value of the differential portion or the vehicle speed differentiating the vehicle speed by being constituted by subtraction unit for subtracting the past value, or the acceleration sensitive table, said at 0 near the deceleration estimated value equal to the front wheel weight X and the rear wheel weight Y, deceleration and by the adapted front wheel weight X is increased during acceleration or the traveling state of the vehicle is running on a rough road, road surface estimated value calculating section for calculating the road surface estimation value from four wheels wheel speed of the vehicle By being provided with the road surface estimated value sensitive table for calculating the front wheel weight X and the rear wheel weight Y on the basis of the road surface estimated value, or the road surface estimating arithmetic unit, each of the four wheels wheel speed calculating a vehicle speed change in the wheel, by which is determined that the vehicle is running a rough road than the maximum acceleration or deceleration and calculates the road surface estimated value, or the road surface estimated value sensitive table, the road surface in the vicinity 0 estimates to equal the wheel weight X and the rear wheel weight Y, by being adapted to increase the rear wheel weights Y in the above predetermined value of the road surface estimated value, or running of the vehicle state is slalom steering travel, by being provided with a steering angular velocity sensing table for calculating the front wheel weight X and the rear wheel weight Y from the motor angular velocity estimate, or the steering Speed ​​sensitive table, the motor angular velocity estimate is small region is equal to the front wheel weight X and the rear wheel weight Y, so the motor angular velocity estimate is largely the wheel weight X when greater than a predetermined value by being, or the traveling state of the vehicle acceleration or deceleration running rough road, a slalom steering travel, the acceleration and deceleration traveling four-wheel estimated steering angle θest1 calculated in, calculated by the rough road 4 wheel estimated steering angle θest2, said Suraro
Effect of the invention
[0017]
　According to the electric power steering apparatus according to the present invention, calculates a front wheel estimated steering angle from the front left and right wheel speed, it calculates a rear-wheel estimated steering angle from the rear left wheel speed, front-wheel estimated steering angle and the rear wheel estimated steering angle , to calculate the four-wheel estimated steering angle by using the traveling state of the vehicle, the front wheel estimated steering angle and the rear wheel estimated steering angle, the correction or 4-wheel estimate 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 the steering angle.
[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. In particular, since it calculates the four-wheel estimated steering angle by using the traveling state of the vehicle, the optimum four-wheel estimated steering angle in each driving state is obtained.
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 section (Example 1-1).
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.
23 is a diagram showing the relative merits of when various traveling states of the actual vehicle running vehicle and the viewpoint of the steering angle estimation method in this case was responsiveness.
Is a block diagram showing the FIG. 24 example of the configuration of the steering angle estimating portion during deceleration traveling (Example 2-1).
It is a block diagram showing a configuration example of FIG. 25 deceleration calculation unit.
FIG. 26 is a characteristic diagram showing an example of acceleration and deceleration sensitive table.
FIG. 27 is a block diagram showing a configuration example of a steering angle estimating portion during running on a rough road (Example 2-2).
[FIG. 28] is a block diagram showing a configuration example of a road estimation calculation unit.
FIG. 29 is a characteristic diagram showing an example of a road surface estimated value sensitive table.
Is a block diagram showing the FIG. 30 example of the configuration of the steering angle estimating portion during slalom steering travel (Example 2-3).
[FIG. 31] is a characteristic diagram showing an example of a motor angular velocity sensing table.
[FIG. 32] is a block diagram showing all the configuration example of the correspondence possible steering angle estimating portion of the running state (Example 2-5).
Is a block diagram showing a modification of the structure of FIG. 33 FIG. 32 (Example 2-6).
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 left and right wheel speeds, the weight of the front wheel estimated steering angle and the rear wheel estimated steering angle, such as acceleration and deceleration running with combined varied to calculate the four-wheel estimated steering angle to the running state, the front wheel estimated steering angle, the rear wheels estimated steering angle, 4-wheel wheel speed, vehicle speed, certainly for a four-wheel estimated steering angle by using a motor angular velocity estimate Rashi of a correction, or by correcting the output of the control using the four-wheel estimated steering angle, without the need for a steering angle sensor, so as to prevent incorrect output.
[0021]
　Further, return handle structure having the above features are 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 estimation calculation section 110 (Embodiment 1) FIG. 6 (A), the (B), as shown (C), the front wheel estimated steering angle θf than relation of the front wheel speed and steering angle theta, the rear wheels seek the rear wheel estimated steering angle θr from the relationship of the wheel speed and steering angle 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.
(Number 3)
? Est = (.theta.f + [theta] r) / 2
　in addition to or above the average value, 4-wheel estimated steering angle? Est, after the rear wheel estimated steering angle [theta] r and the front wheel weight X of the front wheel estimated steering angle .theta.f in accordance with the vehicle speed Vel changing the Waomomi Y, it is 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).
(Number 4)
? Est = (.theta.f × X + [theta] r ×
Y) X + Y = 1.0
　when the wheel weight Y after the front wheel estimated steering angle .theta.f front wheel weight X and the rear wheel estimated steering angle [theta] r, is respectively changed according to the vehicle speed Vel weighting of the construction of the steering angle estimation calculation section 110 of, for example, as shown in FIG. 8 (example 1-1). That is, the front wheel weight X and the rear wheel weight Y from vehicle speed sensitive table 111 by responding to the vehicle speed Vel is output with a relationship "X + Y = 1.0". Rear wheel weights Y is multiplied by the rear-wheel estimated steering angle θr in the multiplication section 112, a front wheel weight X 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.
[0029]
　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.
[0030]
　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, so as to vary according to the steering angular velocity (Example 1-2) and the steering torque (Example 1-3) and it may be.
[0031]
　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.
[0032]
　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.
[0033]
　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.
[0034]
　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.
[0035]
　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 Wr is below the number 5, the rear wheel speed Wf may be calculated by the following Expression 6.
(Number
5) Wf = (WFL + WFR) / 2
(number
6) Wr = (WRL + WRR) / 2
　Further, the driving wheel slip determining section 122 as shown in FIG. 14, the difference between the front wheel speed Wf and the rear wheel speed Wr gradual change calculator calculates the gradual change amount VHD for driving wheel slip gain 122-1, increasing or decreasing the driving wheel slip gain DWG a gradual change VHD for driving wheels slip gain via an output restricted integration unit 122-2 in accordance with the . 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.
[0036]
　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.
[0037]
　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.
[0038]
　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.
[0039]
　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.
[0040]
　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.
[0041]
　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.
[0042]
　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.
[0043]
　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.
[0044]
　Then, the steering angle estimation calculation section 110, an operation example of the weighting unit to apply the respective front wheel weight X and the rear wheel weight Y on the front and rear wheels estimated steering angle θf and [theta] r, referring to the configuration example of the flow chart and Figure 8 in FIG. 20 and it will be described.
[0045]
　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).
[0046]
　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.
[0047]
　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.
[0048]
　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).
[0049]
　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).
[0050]
　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).
[0051]
　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.
[0052]
　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.
[0053]
　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.
[0054]
　In the above-described first embodiment, by changing the wheel weight Y after the front wheel weight X and the rear wheel estimated steering angle θf of the front wheels estimated steering angle θf in accordance with the vehicle speed Vel, but to enhance the robustness, not only the vehicle speed, running state of the vehicle (turning road, gravel road, rubble path, acceleration, etc. deceleration) by further changing the wheel weight X and the rear wheel weights Y in response to, be calculated more accurate four-wheel estimated steering angle θest it can.
[0055]
　Figure 23 is a diagram showing the relative merits of the case where the viewpoint of the steering angle estimation method in this case with various running states of the vehicle running vehicle and responsiveness, the viewpoint is "responsive", the content is "turning road, fast slalom, 70 [km / h] the steering angle estimation method in the case of "very good average estimated steering angle of the front wheels estimated steering angle and the front and rear wheels, the rear wheels estimation becomes bad evaluation. Similarly, the viewpoint is "gravel road", the content is "gravel road, free practice, 30 [km / h]" steering angle estimating method in the case of the average estimated steering angle of the front wheels estimated steering angle and the front and rear wheels is very well, the rear wheel estimation is a bad evaluation. However, in view is "slip", contents "gravel road, slip drive, 30 [km / h]" steering angle estimating method in the case of poor front wheel estimated steering angle and the rear wheel estimated steering angle, of the front and rear wheels the average estimated steering angle is slightly better evaluation. In addition, point of view is "acceleration and deceleration", the content is "comprehensive test road, acceleration and deceleration running, 0 → 100 → 0 [km / h]" steering angle estimation method in the case of extremely good rear-wheel estimated steering angle, good average estimated steering angle of the front and rear wheels, the rear wheels estimated steering angle is also a slightly better evaluation.
[0056]
　Thus, the superiority or inferiority of a method of calculating the estimated steering angle by the running condition of the vehicle occurs, in the second embodiment of the present invention, in accordance with the running state of the vehicle, the rear wheels estimated steering the front wheel weight X of the front wheel estimated steering angle a structure for changing the wheel weight Y after the corner.
[0057]
　The deceleration traveling, the vehicle speed acceleration and deceleration estimated from Vel, changing the wheel weight Y (Example after the front wheel weight X and the rear wheel estimated steering angle θr of the front wheels estimated steering angle θf and sensitive to acceleration and deceleration 2-1 ). Figure 24 is a block diagram showing a configuration example of a weighting section of the steering angle estimation calculation unit of acceleration or deceleration running in correspondence with FIG. 8, the vehicle speed Vel is inputted to the acceleration calculation unit 200, the calculated acceleration wheel weights X and the rear wheel weights Y is calculated estimated value aS is input to the acceleration sensitive table 203. Deceleration calculation section 200, acceleration estimate from the vehicle speed Vel (vehicle speed change) is calculated AS. As shown in FIG. 25, a memory unit 201 which holds the previous value provided by subtracting the previous value from the vehicle speed Vel current value subtraction unit 202 may calculate the deceleration estimated value AS. The vehicle speed Vel may be differentiated. Deceleration estimated value AS is input to the acceleration sensitive table 203, front wheel weight X and the rear wheel weights Y is calculated in accordance with the characteristics shown in FIG. 26.
[0058]
　Near the deceleration estimated value AS = 0, the average value of the front wheel estimated steering angle θf and the rear wheel estimated steering angle θr by equivalent front wheel weight X and the rear wheel weight Y, deceleration (acceleration estimated value AS < 0) and the time of acceleration (deceleration estimated value AS> 0), by increasing the front wheel weight X (the rear wheel weight Y smaller) to calculates a 4-wheel estimated steering angle θest1 with front wheel estimated steering angle θf .
[0059]
　Next, 4-wheel wheel speed Vw than estimates a road surface disturbance, by responding to road surface estimated value RS to change 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 Example 2 -2 is described. 4-wheel wheel speed Vw, as shown in FIG. 27 is inputted to the road surface estimated value calculating unit 210, road surface estimated value calculating unit 210 from the positive and negative peak values ​​of the wheel speed difference to the average value of the four-wheel wheel speed Vw , to estimate the bad road. 4-wheel vehicle speed as shown in FIG. 28 as described with reference to FIG. 25, the change amount calculation unit composed of the memory units 211-214 and the subtraction unit 215-218 to calculate the variation in the vehicle speed at each wheel, the maximum pressure determines that the vehicle is running a rough road than deceleration speed, it calculates the road surface estimated value RS. Change the previous value the second last value, etc., or by changing the operation cycle, to adjust the wheel speed vibration frequency due to road surface disturbance. In the road surface estimated value calculating unit 210 calculates the maximum value than the absolute value of the variation of the wheel speeds, the road surface estimated value RS.
[0060]
　Road estimate RS is inputted to the road surface estimated value sensitive table 220 having the characteristics shown in FIG. 29, a front wheel weight X and the rear wheel weights Y is calculated by the road surface estimated value sensitive table 220. That is, in the vicinity of the road surface estimated value RS = 0, the average value of the front wheel estimated steering angle θf and the rear wheel estimated steering angle θr by equivalent front wheel weight X and the rear wheel weight Y, state road surface is rough (road surface estimate RS = predetermined value RS 0 in more of to a large area), by increasing the wheel weight Y of the rear-wheel estimated steering angle [theta] r (small wheel weights Y), steering with the rear wheels estimated steering angle to calculate the angle estimated value θest2.
[0061]
　Further, the motor angular velocity estimate ratio of the front wheel estimated steering angle and the rear wheel estimated steering angle and sensitive to (steering angular velocity) .omega.m, i.e. may be changed to the front wheel weight X and the rear wheel weight Y (Example 2- 3). Motor angular velocity estimate ωm may be calculated from the steering angular velocity sensor or a resolver angle. Figure 30 shows a configuration example, the motor angular velocity estimate ωm is inputted to a motor angular velocity sensitive table 230, the motor angular velocity sensing table 230 in accordance with characteristics shown in FIG. 31, a front wheel weight X and the rear wheel weight Y calculate. That is, the motor angular velocity estimate .omega.m lower region (predetermined value .omega.m 0 in less than), by the same front wheel weight X and the rear wheel weight Y, the average value of the front wheel estimated steering angle θf and the rear wheel estimated steering angle θr , the motor angular velocity estimate .omega.m predetermined value .omega.m 0 in the above high region, by increasing the front wheel weight X (the rear wheel weight Y smaller) to calculates the steering angle estimated value θest3 with front wheel estimated steering angle.
[0062]
　Incidentally, a motor angular velocity estimate and the steering angular velocity sensor changes suddenly, since the output of the motor angular velocity sensitive table 230 might suddenly changes, may be added to filters and rate limit processing on the input signal (Example 2-4) .
[0063]
　Further, in order to accommodate all of the running state, the above-described deceleration traveling four-wheel steering angle estimated value at the time Shitaest1, four-wheel steering angle estimated value at the time of rough road speed running Shitaest2, 4-wheel steering angle estimating during slalom steering travel using the value Shitaest3, deceleration running in the configuration shown in FIG. 32, rough road, by using the average value of the four-wheel steering angle estimated value computed by each of the running state of the slalom steering travel, all of the running It may be calculated four-wheel estimated steering angle in accordance with the state (example 2-5). That is, by adding the 4-wheel steering angle estimated value θest3 of θest2 and during slalom steering driving four-wheel steering angle estimated value at the time of rough road speed running by an adder 241, by an adder 240 the estimated value θa is the addition result adds a 4-wheel steering angle estimated value θest1 during acceleration or deceleration running, enter an estimate .theta.b its addition result to the divider (or multiplier unit) 242, and the calculation of "θb · 1/3" 4 to calculate the wheel estimated steering angle θest4.
[0064]
　Incidentally, each of the weights in the acceleration travel four-wheel steering angle estimated value at the time Shitaest1, four-wheel steering angle estimated value at the time of rough road speed running Shitaest2, 4-wheel steering angle estimated value θest3 during slalom steering travel as shown in FIG. 33 Xt, Yt, with a Zt (Xt + Yt + Zt = 1.0), may also be calculated four-wheel estimated steering angle θest5 an average value in subsequent to the operation unit 248 (example 2-6).
[0065]
　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
[0066]
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
200 deceleration calculating unit
203 deceleration sensitive table
210 road estimation value calculation unit
220 road estimate sensitive table
230 motor angular velocity sensitive table

claims

[Claim 1]A torque sensor for detecting steering torque input to a steering mechanism of a vehicle, a current command value calculation unit for calculating a current command value based on at least the steering torque, a motor for generating a steering assist torque to be applied to the steering mechanism in the electric power steering apparatus that includes a motor control unit for driving and controlling the motor based on the current command value,
the front wheel weight X and the rear wheel estimated steering angle of the front wheels estimated steering angle in accordance with the traveling state of the vehicle changing the rear wheel weight Y, characterized in that it comprises the steering angle estimation calculation section for calculating a four-wheel estimated steering angle based on the front wheel weight X and the rear wheel weight Y (X + Y = 1.0) electric power steering system.
[Claim 2]
Traveling state of the vehicle is the acceleration and deceleration running,
acceleration and deceleration to calculate the acceleration and deceleration calculation unit for calculating an acceleration estimate from the vehicle speed, the front wheel weight X and the rear wheel weight Y on the basis of the acceleration estimate the electric power steering apparatus according to claim 1, which comprises a sensitive table.
[Claim 3]
The deceleration calculation unit, an electric power of claim 2 in which the memory unit and the current value is composed of a subtraction unit for subtracting the past value holds the past value of the differential portion or the vehicle speed differentiating the vehicle speed steering system.
[Claim 4]
Said deceleration-sensitive table,
the acceleration and deceleration at the 0 near the estimated value equal to the front wheel weight X and the rear wheel weight Y, deceleration and acceleration claim adapted to the front wheel weight X is increased during 2 or an electric power steering apparatus according to 3.
[Claim 5]
The traveling state of the vehicle is running on a rough road,
and the road surface estimated value calculating section for calculating the road surface estimation value from four wheels wheel speed of the vehicle, the front wheel weight X and the rear wheel weight Y on the basis of the road surface estimated value the electric power steering apparatus according to claim 1 which comprises the road surface estimated value sensitive table calculated.
[Claim 6]
The road estimation calculation unit calculates the vehicle speed change in each of the wheels from said four wheels wheel speed, which is determined to be traveling on a rough road than the maximum acceleration and deceleration so as to calculate the road surface estimated value the electric power steering apparatus according to claim 5.
[Claim 7]
The road estimate sensitive table,
said at 0 near the road surface estimated value equal to the front wheel weight X and the rear wheel weight Y, so as to increase the rear wheel weights Y in the above predetermined value of the road surface estimated value and has an electric power steering apparatus according to claim 5 or 6.
[8.]
The traveling state of the vehicle is slalom steering travel,
the electric power steering apparatus according to claim 1 which comprises a steering angular velocity sensing table for calculating the front wheel weight X and the rear wheel weight Y from the motor angular velocity estimate.
[Claim 9]
The steering angular velocity sensing table,
said motor angular velocity estimate is smaller region equal to the front wheel weight X and the rear wheel weight Y, so that the motor angular velocity estimate is largely the wheel weight X when greater than a predetermined value the electric power steering apparatus according to to have claim 8 becomes.
[Claim 10]
The traveling state of the vehicle is acceleration or deceleration running rough road, a slalom steering travel,
the acceleration and deceleration are calculated by running four-wheel estimated steering angle Shitaest1, the bad road is calculated by running four-wheel estimated steering angle Shitaest2, the electric power steering apparatus according to the average value of the four-wheel estimated steering angle θest3 calculated in the slalom steering traveling in claim 1, wherein the four-wheel estimated steering angle.
[Claim 11]
The four-wheel estimated steering angle θest1, θest2 and θest3 each weight Xt, Yt and Zt (Xt + Yt + Zt = 1.0) The electric power steering apparatus according to to have claim 10 adapted put.