JP5401875B2 - Steering angle detection device for vehicle and electric power steering device using the same - Google Patents

Description

  The present invention relates to a vehicle steering angle detection device that detects an absolute steering angle of a steering mechanism of a vehicle, and an electric power steering device using the same.

  As a conventional vehicle rudder angle detection device, for example, two types of signals shifted by a quarter cycle at the angular interval are output by a slit part of a slit disk and a detection part composed of two sets of photo interrupters. The angular position of one of the signals from the on point is counted by the corresponding frequency counter, and the steering neutral is specified by the frequency calculation by this frequency counter. After a predetermined number of samples is obtained, the steering neutral from the frequency to the average is obtained. Therefore, a steering neutral calculation device has been proposed in which the steering neutral is quickly determined in the early stage of traveling, and thereafter the steering neutral is closer to a more accurate one (see, for example, Patent Document 1).

Further, a steering count value that increases / decreases according to the steering angle of the steering wheel is obtained, and the steering angle peaks MAX, MIN in the right direction and the left direction are detected based on the increase / decrease tendency, and MAX, MIN are continuously detected within a predetermined period. Is detected, only the last peak is regarded as an effective value, and MAX and MIN detected in the vicinity of the straight-ahead state and MAX or MIN not detected continuously in MAX or MIN are not detected. There has also been proposed a neutral position detection device that is adopted as PKH and PKL and used as basic data for neutral position calculation (see, for example, Patent Document 2).
Japanese Patent No. 3341345 JP-A-8-122054

However, the conventional example described in Patent Document 1 requires a complicated calculation such as recording the frequency at which the rudder angle appears and the average of the rudder angle, and erroneous estimation due to a long turn or the like. There is an unsolved problem that is likely to occur.
Further, in the conventional example described in Patent Document 2, since the neutral point is calculated by averaging the peak values of the left and right steering angles, there is a possibility of erroneous estimation due to a long turn or one of the corrected rudder. There is an unsolved problem that there is an unsolved problem, and there is an unsolved problem that the neutral point position needs to be known.
Accordingly, the present invention has been made paying attention to the unsolved problems of the above-described conventional example, and a vehicle that can suppress erroneous estimation due to a long turn or a one-sided rudder with a simple arithmetic process. An object of the present invention is to provide a steering angle detection device for an automobile and an electric power steering device using the same.

To achieve the above object, a vehicle steering angle detection device according to claim 1 stores a relative steering angle detection means for detecting a relative steering angle θr of a steering mechanism of a vehicle, and a known vehicle total steering angle range θt. The steering mechanism based on the total steering angle range storage means, the vehicle total steering angle range θt stored in the total steering angle range storage means, and the relative steering angle θr detected by the relative steering angle detection means. Absolute steering angle estimated value calculating means for calculating the absolute steering angle estimated value θa of the steering wheel , and the absolute steering angle estimated value calculating means increases the positive direction of the relative steering angle θr with a positive / negative sign during steering. The maximum value θrmax of the relative rudder angle θr that is maximum when the negative direction is small and the minimum value θrmin of the relative rudder angle θr that is minimum when the positive direction is large and the negative direction is small are detected. And a steering range detecting means for detecting the steering range. Based on the maximum value θrmax and minimum value θrmin detected by the means and the vehicle total steering angle range θt, the maximum value θnmax and the minimum value θnmin of the neutral point existing steering angle range where the neutral point of the steering angle exists are estimated, A midpoint rudder angle range computing unit that computes a midpoint rudder angle range θrange based on the estimated maximum value θnmax and minimum value θnmin and the vehicle total rudder angle range θt, and the midpoint rudder angle range computation unit And an absolute rudder angle calculation unit that calculates an absolute rudder angle estimated value θa based on the maximum value θnmax and the minimum value θnmin of the midpoint rudder angle range .

Further, in the vehicle steering angle detection device according to claim 2 , in the invention according to claim 1 , the midpoint steering angle range calculation unit calculates the maximum value θrmax and the minimum value θrmin of the relative steering angle θr and the total vehicle Based on the steering angle range θt,
θnmax = (θrmax + θrmin) / 2 + {θt− (θrmax−θrmin)} / 2
θnmin = (θrmax + θrmin) / 2− {θt− (θrmax−θrmin)} / 2
θrange = θnmax−θnmin
The neutral point rudder angle range θrange is calculated by performing the above calculation.

Furthermore, a steering angle detecting apparatus for a vehicle according to claim 3, in the invention according to claim 1 or 2, if the full steering angle range θt is asymmetrical with respect to the neutral point, the neutral by straight travel determination Neutral point left / right difference estimating means for estimating the left / right difference θncop, and the neutral left / right difference estimating means, which is an average value of the maximum value θrmax and the minimum value θrmin of the relative steering angle θr based on the estimated neutral left / right difference θncop. The neutral point provisional value correction means for correcting the neutral point provisional value θntemp, the neutral point right / left difference storage means for storing the neutral point left / right difference θncop in the nonvolatile memory, and stored in the nonvolatile memory at the start of the vehicle The neutral point steering angle initial correcting means for correcting the neutral point provisional value θntemp based on the neutral point left-right difference θncop is provided.

Still further, in the invention according to any one of claims 1 to 3 , the vehicle steering angle detection device according to claim 4 is an absolute value for the absolute steering angle estimation value θa based on the neutral point steering angle range θrange. A dead zone setting means for setting a rudder angle dead zone is provided, and the absolute rudder angle estimating means estimates an absolute rudder angle estimated value θa based on the relative rudder angle θr, the neutral point rudder angle range θ range and the absolute rudder angle dead zone. It is characterized by being configured.
An electric power steering apparatus according to a fifth aspect includes the vehicle steering angle detection device according to any one of the first to fourth aspects, and the steering wheel absolute steering detected by the vehicle steering angle detection apparatus. The steering control is performed based on the angle.

According to the present invention, the absolute value of the steering mechanism is determined based on the relative steering angle θr of the vehicle steering mechanism detected by the relative steering angle detection means and the known total steering angle range stored in the total steering angle range storage means. Since the steering angle estimated value θa is calculated, the accurate absolute steering angle estimated value θa can be calculated without performing complicated calculation processing.
Further, the absolute rudder angle estimated value calculation means calculates the maximum of the neutral point existing rudder angle range where the neutral point of the rudder angle exists based on the maximum value θrmax and the minimum value θrmin of the relative rudder angle θr and the vehicle total rudder angle range θt. A value θnmax and a minimum value θnmin are estimated, a neutral point steering angle range θnrange is calculated based on the estimated maximum value θnmax and minimum value θnmin and the vehicle total steering angle range θt, and the maximum of the neutral point steering angle range θnrange is calculated. By calculating the absolute rudder angle θa based on the value θnmax and the minimum value θnmin, it is possible to calculate an accurate neutral point while suppressing erroneous estimation due to a long turn or one of the modified rudder.
Further, by applying the vehicle steering angle detection device having the above effects to the electric power steering device, steering control such as steering wheel return control can be performed accurately.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
FIG. 1 is an overall configuration diagram showing an embodiment in which the present invention is applied to a steering device. In the figure, reference numeral 1 denotes a steering wheel, and a steering force applied to the steering wheel 1 from a driver. Is transmitted to the steering shaft 2 as a rotating body. The steering shaft 2 includes an input shaft 2a having one end connected to the steering wheel 1 and an output shaft 2b connected to the other end of the input shaft 2a via a torsion bar (not shown). Then, the steering torque transmitted to the steering shaft 2 is detected by the steering torque sensor 4.

  On the other hand, the steering force transmitted to the output shaft 2 b is transmitted to the lower shaft 6 via the universal joint 5 and further transmitted to the pinion shaft 8 via the universal joint 7. The steering force transmitted to the pinion shaft 8 is transmitted to the tie rod 10 via the steering gear mechanism 9 to steer a steered wheel (not shown). Here, the steering gear mechanism 9 is configured in a rack and pinion type having a pinion 9a connected to the pinion shaft 8 and a rack 9b meshing with the pinion 9a, and the rack 9b transmits the rotational motion transmitted to the pinion 9a. It has been converted to straight movement.

  A steering assist mechanism 11 for transmitting a steering assist force to the output shaft 2b is connected to the output shaft 2b of the steering shaft 2. The steering assist mechanism 11 includes a speed reduction mechanism 12 connected to the output shaft 2b, and an electric motor 13 composed of, for example, a DC motor that generates a steering assist force connected to the speed reduction mechanism 12. The electric motor 13 is provided with a motor angle sensor 14 composed of an encoder, a resolver and the like for detecting the rotation angle θm.

  Then, the steering torque T, the motor angle θm, and the vehicle speed detection value Vs detected by the steering torque sensor 4, the motor angle sensor 14, and the vehicle speed sensor 15 are input to the control device 16, and the absolute steering angle estimated value θa is obtained by the control device 16. While calculating, the drive control of the electric motor 13 is performed. Further, direct current power from the battery 17 is supplied to the control device 16 directly and via the ignition switch 18.

  The control device 16 is configured by a microcomputer, for example, and the configuration is shown in FIG. 2 in a functional block diagram. That is, the control device 16 receives the steering torque T detected by the steering torque sensor 4 and the vehicle speed detection value Vs detected by the vehicle speed sensor 15, and calculates the current command value calculation for calculating the current command value Iref for the electric motor 13 based on these. Current feedback for calculating a voltage command value by performing a current feedback process based on the current command value Iref calculated by the unit 21 and the current command value calculation unit 21 and the motor current Im detected by the motor current detection unit 19 A control unit 22 and a motor drive circuit 23 that drives the electric motor 13 by receiving the voltage command value Vref calculated by the current feedback control unit 22 are provided.

  The control device 16 is obtained from the stroke of the rack 9b of the steering gear mechanism 9 and the distance (for example, 50 mm / rotation) that the rack 9b moves when the steering wheel 1 rotates once, that is, when the pinion shaft 8 rotates once. Based on a non-volatile memory 24 configured by, for example, an EEPROM for storing a known total rudder angle range θt, a total rudder angle range θt stored in the non-volatile memory 24, and motor angle information detected by the motor angle sensor 14. Based on the calculated relative rudder angle θr, an absolute rudder angle calculation unit 26 that calculates an absolute rudder angle estimated value θa, and an absolute rudder angle estimated value θa calculated by the absolute rudder angle calculation unit 26 is differentiated to obtain an absolute rudder angular velocity. A differential circuit 27 for calculating ω, an absolute steering angle estimated value θa calculated by the absolute steering angle calculator 26, an absolute steering angular speed ω calculated by the differential circuit 27, and a vehicle speed detection A steering wheel return control unit 28 that performs so-called steering wheel return control that returns the steering wheel 2 to the neutral position when the steering force to the steering wheel 1 is loosened in a steered state based on the value Vs, and the steering wheel return control unit 28 An adder 29 is provided that adds the calculated handle return control signal HR and the current command value Iref output from the current command value calculation unit 21 and supplies the sum to the current feedback control unit 22.

  Here, in the nonvolatile memory 24, as described above, the total steering angle obtained from the rack stroke determined by the specification of the steering gear mechanism 9 and the distance the rack 9b moves when the steering wheel 1 is rotated once. By storing the range θt, or by detecting the steering angle from the state in which the steering wheel 2 contacts one rack end to the other rack end when the final adjustment of the steering device 1 at the time of factory shipment is completed The obtained total rudder angle range θt is stored.

Further, as shown in FIG. 2, the absolute steering angle calculation unit 26 includes a ROM 26a for storing various programs such as a motor angle sensor and an absolute steering angle calculation process executed by the absolute steering angle calculation unit 26, and an absolute steering angle calculation. A RAM 26b that stores values and the like required in the course of each process executed by the unit 26 is connected.
As shown in FIG. 3, the absolute steering angle calculation unit 26 includes a relative steering angle calculation unit 31 that calculates a relative steering angle θr based on the motor angle θm output from the motor angle sensor 14. The relative steering angle θr output from the steering angle calculation unit 31 is input to the maximum value detection unit 32 and the minimum value detection unit 33.

  The maximum value detection unit 32 receives the relative steering angle θr from the relative steering angle calculation unit 31 on the input side, and is connected to the delay unit 34 that delays and holds the previous maximum value θrmax (n−1) on the output side. The previous maximum value θrmax (n−1) held in the delay unit 34 is supplied to the input side. Then, the maximum value detection unit 32 compares the input relative steering angle θr with the previous maximum value θrmax (n−1), and when θr> θrmax (n−1), the input relative steering angle. The angle θr is output as the maximum value θrmax (n). When θr ≦ θrmax (n−1), the previous maximum value θrmax (n−1) is output as the maximum value θrmax (n).

  The minimum value detection unit 33 receives the relative steering angle θr from the relative steering angle calculation unit 31 on the input side, and is connected to the delay unit 35 that delays and holds the previous minimum value θrmin (n−1) on the output side. The previous minimum value θrmin (n−1) held in the delay unit 35 is supplied to the input side. The minimum value detection unit 33 compares the input relative rudder angle θr with the previous minimum value θrmin (n−1). When θr <θrmin (n−1), the input relative rudder angle is compared. The angle θr is output as the minimum value θrmin (n), and when θr ≦ θrmin (n−1), the previous minimum value θrmin (n−1) is output as the minimum value θrmin (n).

  Then, the maximum value θrmax (n) output from the maximum value detection unit 32 and the minimum value θrmin output from the minimum value detection unit 33 are added by the adder 36, and the addition output of the adder 36 is ½. Is supplied to a multiplier 37 to calculate a neutral point provisional value θntemp. Then, by supplying the calculated neutral point provisional value θntemp to the subtractor 38 and subtracting the neutral point provisional value θmtemp from the relative rudder angle θr, the absolute rudder angle provisional value θatemp is calculated, and the calculated absolute rudder angle provisional The value θatemp is output to the dead zone setting unit 39.

  On the other hand, the maximum value θrmax (n) output from the maximum value detector 32 and the minimum value θrmin (n) output from the minimum value detector 33 are supplied to the subtractor 40, and the minimum value θrmax (n) is determined from the maximum value θrmax (n). The value θrmin (n) is subtracted, and the subtracted value and the total steering angle range value θt read from the nonvolatile memory 24 are supplied to the subtractor 41, and the subtracted value (θrmax (n ) −θrmin (n)) is subtracted to calculate the neutral point steering angle range θrange. Then, the calculated neutral point rudder angle range θrange is directly supplied to the dead band width setting unit 39, and is also supplied to the multiplier 42 that multiplies the neutral point rudder angle range θrange by 1/2 to calculate the dead band width θdb. The dead zone width θdb is supplied to the dead zone setting unit 39.

  The dead zone setting unit 39 determines whether or not to output the absolute steering angle θa based on the neutral-point steering angle range θrange, and when the determination result does not output the absolute steering angle θa, the absolute steering angle θa When the output is prohibited and the absolute steering angle is output, the absolute steering angle provisional value θatemp input is compared with the dead zone width θdb. When the relationship between the two is −θdb ≦ θatemp ≦ θdb, When the steering angle θa is set to “0”, θa = θatemp−θdb is calculated when θatemp> θdb, and the absolute steering angle θa is calculated. When θatemp <−θdb, θa = θatemp + θdb is calculated. The absolute steering angle θa is calculated, and the calculated absolute steering angle θa is output to the differentiation circuit 27 and the steering wheel return control unit 28.

This dead band width setting unit 39 executes a dead band setting process shown in FIG.
In this dead zone setting process, first, in step S1, the input absolute steering angle provisional value θatemp, neutral point steering angle range θrange and dead zone width θdb are read, and then the process proceeds to step S2 where the neutral point steering angle range θrange is obtained. It is determined whether or not the predetermined value θns or less. This determination is performed to determine whether or not the absolute steering angle estimated value θa is to be output. When θrange> θns, the steering range of the steering wheel 1 after starting is small and the maximum of the neutral-point steering angle range θrange When it is determined that a stable neutral point with a small deviation between the value θnmax and the minimum value θnmin cannot be obtained, the process proceeds to step S3, the output of the absolute steering angle estimated value θa is prohibited, and the process returns to step S1.

On the other hand, when the determination result of step S2 is θrange ≦ θns, the steering range of the steering wheel 1 is increased, the neutral point steering angle range θrange is expanded, and a stable neutral point can be obtained, and the absolute steering angle estimated value θa Is determined to be possible, and the process proceeds to step S4.
In this step S4, it is determined whether or not the absolute steering angle provisional value θatemp read in step S1 is within the range of the dead zone widths −θdb and θdb. If −θdb ≦ θatemp ≦ θdb, it is within the dead zone width. If it is determined that there is, the process proceeds to step S5, the absolute steering angle estimated value θa is set to “0”, and the process proceeds to step S9.

  When the determination result of step S4 is not within the dead zone width, the routine proceeds to step S6, where it is determined whether or not the absolute steering angle provisional value θatemp is larger than the dead zone width θdb. When θatemp> θdb, the routine proceeds to step S7. Then, a value obtained by subtracting the dead zone width θdb from the absolute steering angle provisional value θatemp (θatemp−θdb) is set as the absolute steering angle estimated value θa, and then the process proceeds to step S9.

Furthermore, when the determination result in step S4 is θatemp <−θdb, the process proceeds to step S8, and a value (θatemp + θdb) obtained by adding the dead zone width θdb to the absolute steering angle provisional value θatemp is set as the absolute steering angle estimated value θa. Then, the process proceeds to step S9.
In step S9, the absolute steering angle estimated value θa set in any of step S5, step S7 and step S8 is output to the differentiation circuit 27 and the steering wheel return control unit 28, and then the process returns to step S1.

  For this reason, the absolute rudder angle estimated value θa output from the dead band setting unit 39 is such that the absolute rudder angle estimated value θa is “0” when the provisional absolute rudder angle value θatemp shown in FIG. 5 is in the range of the dead band width −θdb to θdb. When the absolute steering angle provisional value θatemp is smaller than the dead zone width −θdb, a value obtained by adding the dead zone width θdb to the absolute steering angle provisional value θatemp becomes the absolute steering angle estimated value θa, and conversely, the absolute steering angle provisional value θatemp Is larger than the dead zone width θdb, a value obtained by subtracting the dead zone width θdb from the absolute steering angle provisional value θatemp is the absolute steering angle estimated value θa.

Here, the absolute rudder angle θa in the absolute rudder angle calculation unit 26 is basically calculated by the following formulas (1) to (3) to obtain a neutral point rudder angle range θrange in which a neutral point exists. The absolute steering angle estimated value θa is calculated by calculating the average value of the maximum value θnmax and the minimum value θnmin of the calculated neutral point steering angle range θrange.
θnmax = (θrmax + θrmin) / 2 + {θt− (θrmax−θrmin)} / 2
………… (1)
θnmin = (θrmax + θrmin) / 2− {θt− (θrmax−θrmin)} / 2
………… (2)
θrange = θnmax−θnmin (3)
That is, if the above formula (1) is arranged,
θnmax = θrmin + θt / 2 (4)
And
Organizing the equation (2),
θnmin = θrmax−θt / 2 (5)
It becomes.

The neutral point provisional value θntemp is an average value of the maximum value θnmax and the minimum value θnmin of the neutral point steering angle range θnrange, and the following equation (6) is obtained by substituting the above equations (4) and (5). The neutral point steering angle range θrange can be expressed by the following equation (7) by substituting the above equations (4) and (5) into the above equation (3).
θntemp = (θnmax + θnmin) / 2
= (Θrmax + θrmin) / 2 (6)
θrange = θnmax−θnmin
= Θt− (θrmax−θrmin) (7)

  Therefore, as shown in FIG. 3, the output of the multiplier 37 becomes the neutral point provisional value θntemp, and by subtracting the neutral point provisional value θntemp from the relative steering angle θr, the absolute steering angle provisional value θatemp can be calculated. it can. Further, the output of the subtractor 41 becomes the neutral point rudder angle range θrange, and a value ½ of the neutral point rudder angle range θrange is set as the dead zone width θdb.

Further, as shown in FIG. 6, the steering wheel return control unit 28 outputs a steering wheel return basic current circuit 50 that outputs a steering wheel return basic current value Ir using a predetermined function based on the absolute steering angle estimated value θa, and a vehicle speed detection value Vs. A gain circuit 51 that inputs and outputs a gain Gv corresponding to the detected vehicle speed Vs by a predetermined function, and a multiplication that multiplies the handle return basic current value Ir from the handle return basic current circuit 50 and the gain Gv from the gain circuit 51. A switch 52 for switching the output Ir · Gv from the multiplier 52 to the contact point a or b and outputting it, and a zero output circuit 54 for setting the output when the switch 53 is switched to the contact point b side to zero. An absolute rudder angle estimation θa and an absolute rudder angular velocity ω are input, and a code determination circuit 55 that determines the coincidence or non-coincidence of the signs of both.
The sign determination circuit 55 outputs a switch signal SW as a determination signal to switch the contact of the switch 53, but switches to the contact b with the switch signal SW when the signs of the absolute steering angle estimated value θa and the steering angular speed ω match. Further, the contacts a and b of the switch 53 are configured to be switched from a circuit (not shown) that detects that the steering angular speed ω is zero.

Next, the operation of the above embodiment will be described.
Assuming that the vehicle is stopped and the ignition switch 18 is in an off state, the battery voltage Vb from the battery 17 via the ignition switch 18 is not supplied to the control device 16 in this state. The steering assist control process executed based on the steering torque T and the vehicle speed detection value Vs shown in FIG. 3 is in the stop state, and the electric motor 13 is stopped and the steering assist force is transmitted to the steering shaft 3. Is not done.

  When the ignition switch 18 is turned on from this vehicle stop state, the battery voltage Vb is supplied to the control device 16 so that the control device 16 is in an operating state, and the motor current detection unit 19 of FIG. The steering assist control by the value calculation unit 21, the current feedback control unit 22, the motor drive circuit 23, the steering wheel return control unit 28, and the adder 29 and the absolute steering angle calculation of the absolute steering angle calculation negative 26 are started.

  In this state, when the steering wheel 1 is not being steered, since the steering torque T detected by the steering torque sensor 4 is “0”, the current command value Iref calculated by the current command value calculation unit 21 is “0”. The voltage command value Vref output from the current feedback control unit 22 also becomes “0”, the motor current Im is not output from the motor drive circuit 23, and the electric motor 13 maintains the stopped state.

  At this time, since the steering wheel 1 is not steered and the electric motor 13 is in a stopped state, the current motor angle θm is output from the motor angle sensor 14, and the relative steering angle calculation unit 31 responds to the motor angle θm. However, since the relative steering angle θr does not change, the maximum value θrmax and the minimum value θrmin also have the same value as the relative steering angle θr. For this reason, the output of the subtractor 40 is substantially “0”, and the neutral point steering angle range θrange calculated by the subtractor 41 becomes substantially equal to the total steering angle range value θt. Therefore, in the dead zone setting process of FIG. 4 in the dead zone setter 39, it is determined in step S2 that θrange> θns, so that the process proceeds to step S3 and the output of the absolute steering angle estimated value θa is prohibited.

  Therefore, in the steering wheel return control unit 28, the absolute steering angle estimation value θa is not input from the absolute steering angle calculation unit 26, so that the steering wheel return control signal HR is set to “0” and is supplied to the adder 29. Therefore, the adder 29 outputs the current command value Iref based on the steering torque T calculated by the current command value calculation unit 21 and the vehicle speed detection value Vs to the current feedback control unit 22 as it is.

At this time, since the driver is not steering the steering wheel 1, as described above, the motor current Im output from the motor drive circuit 23 is also "0", and the electric motor 13 continues to be stopped. To do.
From this state, when the driver steers the steering wheel 1 to a so-called stationary state, a relatively large steering torque T is output from the steering torque sensor 4 in response to this, so that the current command value calculation unit 21 A relatively large current command value Iref corresponding to the steering torque T and the vehicle speed detection value Vs is output.

At this time, the electric motor 13 is in a stopped state, and the motor current Im detected by the motor current detection unit 19 maintains “0”. Therefore, the current feedback control unit 22 receives a relatively large voltage command value Vref. Is output to the motor drive circuit 23, and a relatively large value of the motor drive current Im is output from the motor drive circuit 23 to the electric motor 13.
For this reason, the electric motor 13 is rotationally driven to generate a relatively large steering assist force, and this steering assist force is transmitted to the steering shaft 3 via the speed reduction mechanism 12, so that the steering wheel 1 is lightly steered. Can do.

  When the vehicle is started in this state, the vehicle speed detection value Vs increases, and the maximum value θrmax and the minimum value θrmin of the relative steering angle θr change in a direction in which the deviation between the two increases by the left and right steering of the steering wheel 1. To do. Then, when the deviation between the maximum value θrmax and the minimum value θmin becomes large and the neutral point steering angle range θrange calculated by the subtractor 41 is equal to or less than a predetermined value θns set in advance, the dead band setting process of FIG. The process proceeds from S2 to step S4, and the calculation process of the absolute steering angle estimated value θa is started.

  Therefore, when the vehicle is traveling straight ahead with the steering wheel 1 in the neutral position, the absolute steering angle provisional value θatemp obtained by subtracting the neutral point provisional value θntemp from the relative steering angle θr output from the subtractor 38 is the subtractor 41. Is within the width of the dead zone width ± θdb, which is a half value of the neutral-point rudder angle range θrange calculated in step S4, the process proceeds from step S4 to step S5, and the absolute rudder angle estimated value θa is “0”. The absolute steering angle estimated value θa thus set is output to the differentiation circuit 27 and the steering wheel return control unit 28. In this state, since the absolute steering angle estimated value θa is “0” in the steering wheel return control unit 28, the steering wheel return basic current value Ir becomes “0”, and the steering wheel return control is performed even when the steering wheel 1 is steered within the dead zone width. The signal HR continues to be “0”.

Thereafter, the steering wheel 1 is turned to the left (or right) beyond the dead band width to the left steering state (or the right steering state), thereby increasing (or decreasing) the motor angle θm detected by the motor angle sensor 14. When the relative rudder angle θr calculated by the relative rudder angle calculation unit 31 increases and the absolute rudder angle provisional value θatmp calculated by the subtractor 38 exceeds the dead band width θdb, the dead band setting process of FIG. In step S4, the process proceeds from step S4 to step S6 to step S7, and a value obtained by subtracting the dead zone width θdb from the absolute steering angle provisional value θatemp (θatemp−θdb) is set as the absolute steering angle estimated value θa. The estimated value θa is output to the differentiation circuit 27 and the handle return control unit 28.
For this reason, in the handle return control unit 28, the switch signal SW is output from the sign determination circuit 55 when it is determined that the direction is increased, so that the state where the switch 53 is switched to the b contact side is maintained.

  After that, when the steering wheel 2 is turned right (or left) and returned to the neutral position, the absolute rudder angle estimated value θa is positive (or negative) and the absolute rudder angular velocity ω is negative (or positive). Since the signs of the two are different, it is determined that the steering wheel is in the returning state, and the switch 33 of the steering wheel returning control unit 28 is switched to the a contact side, whereby the steering wheel returning basic current is based on the absolute steering angle estimated value θa. A value Ir · Gv obtained by multiplying the steering wheel return basic current value Ir calculated by the circuit 50 by the vehicle speed sensitive gain Gv output from the gain circuit 51 by the multiplier 52 is output to the adder 29 as the steering wheel return control signal HR. . For this reason, good handle return control can be performed only when the handle is returned.

As described above, in the first embodiment, the absolute steering angle calculation unit 26 calculates the absolute steering angle estimated value θa based on the vehicle total steering angle range θt and the relative steering angle θr. The absolute rudder angle estimated value θa can be accurately calculated without setting a neutral point in advance.
Moreover, the maximum value θnmax and the minimum value θnmin of the neutral point existing steering angle range where the neutral point exists are estimated and estimated based on the maximum value θrmax and minimum value θrmin of the relative steering angle θr and the vehicle total steering angle range θt. A neutral point steering angle range θrange is calculated based on the maximum value θnmax and minimum value θnmin and the vehicle total steering angle range θt, and an absolute steering angle estimated value is calculated based on the maximum value θnmax and minimum value θnmin of the neutral point steering angle range θrange. Since θa is calculated, it is possible to calculate an accurate absolute rudder angle estimated value θa while suppressing erroneous estimation due to a long turn or one of the modified rudder.

In this case, by applying the above-described equations (1) to (3), the neutral point steering angle range θnrange, its maximum value θnmax and minimum value θnmin can be accurately calculated, and accurate absolute steering angle estimation is possible. The value θa can be calculated.
In practice, the processing time can be reduced with a simple configuration by adopting the circuit configuration shown in FIG. 3 in which the above-described formulas (1) to (3) are arranged.

  Further, by setting a half value of the neutral point rudder angle range θrange as the dead zone width θdb and performing the dead zone setting process of FIG. 4 by the dead zone setting unit 39 based on the dead zone width θdb, as shown in FIG. Even if it changes near the neutral point of the absolute steering angle estimate value θa, a dead zone for setting the absolute steering angle estimation value θa to “0” is provided, so that the steering control malfunction due to the steering angle estimation error can be avoided. can do. For example, the occurrence of the reverse assist state of the handle return control by the handle return control unit 28 can be reliably suppressed by the estimation error.

  Further, if the neutral point rudder angle range θrange is too large, that is, the rudder angle range when the steering wheel 1 is steered is small and the rudder angle range in which the neutral point may exist is too large, the absolute rudder angle estimated value By prohibiting the output of θa, the neutral point provisional value θntemp is not stable and the absolute steering angle estimation value θa with low reliability is not output, so that the steering control of the absolute steering angle estimation value θa with low reliability is not performed. It is possible to reliably prevent malfunction.

Next, a second embodiment of the present invention will be described with reference to FIG.
In the second embodiment, the neutral point left-right difference θncop representing the deviation amount of the neutral point provisional value θntemp from the actual neutral point is corrected.
That is, in the second embodiment, as shown in FIG. 7, the neutral point left-right difference θncop is stored in the nonvolatile memory 24, and the neutral point left-right difference θncop stored in the nonvolatile memory is changed to that shown in FIG. The first embodiment described above, except that the adder 43 provided on the output side of the multiplier 37 is added to the neutral point provisional value θntemp output from the multiplier 37 in the absolute steering angle calculation unit 26. It has the same configuration as that of the embodiment, and the same reference numerals are given to the corresponding parts to those in FIG.

  In the second embodiment, as the neutral point left-right difference θncop stored in the nonvolatile memory 24, a value obtained by actually measuring the deviation amount of the neutral point in the final assembly process of the production line is stored, or a straight traveling state is detected. Each time, the relative steering angle θr at that time is set as the straight steering relative steering angle θrn, and the deviation between the straight steering relative steering angle θrn and the neutral point provisional value θntemp is stored in the nonvolatile memory 24 as the neutral point left-right difference θncop. When the vehicle is started and updated, the neutral point left-right difference θncop at the end of the previous travel stored in the nonvolatile memory 24 may be read and used.

  Here, as shown in FIG. 8, a self-aligning torque estimator for estimating the self-aligning torque SAT of the vehicle is used as the neutral-point left-right difference calculating unit that detects the straight traveling state and calculates the neutral point left-right difference θncop. 60, a straight traveling state determination unit 61 that determines the straight traveling state of the vehicle, and a straight steering relative steering angle θrn that is compared with the neutral point provisional value θntemp when the straight traveling state determination unit 61 determines that the vehicle is traveling straight. A neutral point left / right difference estimation unit 62 that stores the neutral point left / right difference θncop in the nonvolatile memory 24, and calculates a deviation between the calculated straight relative steering angle θrn and the neutral point provisional value θntemp as a neutral point left / right difference θncop. Is provided.

Here, the self-aligning torque estimation unit 60 differentiates the steering torque T input from the steering torque sensor 4 and the motor rotation angle θm detected by the motor angle sensor 14 to calculate the motor rotation angular velocity ωm. Motor angular velocity ωm input from the unit 14a, motor angular acceleration αm input from the motor angular acceleration calculation unit 14b that calculates the motor angular acceleration αm by differentiating the motor angular velocity ωm, and output from the current command value calculation unit 21 And a self-aligning torque SAT input to the steering mechanism from the road surface via the steered wheels 6 by calculating the following equation (8) based on the current command value Iref to be calculated. .
SAT (s) = Tm (s) + T (s) − J ・ αm (s) − Fr ・ sign (ωm (s)) ………… (8)
Here, Tm (s) is an assist torque generated by the electric motor 13, T (s) is a steering torque, J is an inertia of the electric motor 13, Fr is a static friction of the electric motor 13, and s is a Laplace operator. Since the assist torque Tm (s) is proportional to the steering assist current command value Iref, the steering assist current command value Iref is applied instead of the assist torque Tm.

  Further, the straight traveling state determination unit 61 receives the self-aligning torque SAT estimated by the self-aligning torque estimation unit 60, the motor angular speed ωm calculated by the motor angular speed calculation unit 14a, and the vehicle speed detection value Vs detected by the vehicle speed sensor 15. Straight running condition in which the self-aligning torque SAT is equal to or less than the self-aligning torque threshold value SATth, the motor angular speed ωm is equal to or less than the motor angular speed threshold value ωmth, and the vehicle speed detection value Vs is equal to or greater than the vehicle speed threshold value Vsth. When the straight travel condition is satisfied, the neutral value left / right difference estimation unit 62 generates a straight travel determination signal Sd having a logical value “1” when the straight travel condition is satisfied and a logical value “0” when the straight travel condition is not satisfied. Output to.

  The neutral point left / right difference estimation unit 62 includes two open / close switches 63a and 63b which are turned on when the straight traveling determination signal Sd output from the straight traveling state determination unit 61 is a logical value “1”. The relative steering angle θr calculated by the relative steering angle calculation unit 31 is input to the switch 63a, and the vehicle speed detection value Vs is input to the other opening / closing switch 63b. Connected to the output side of the open / close switch 63a is a subtractor 64 to which a previous neutral point estimated value θc (n-1) held by a delay unit 73 described later is input. 65.

On the other hand, a Dv table 66 for outputting a reliability coefficient Dv corresponding to the vehicle speed detection value Vs is connected to the output side of the open / close switch 63b, and the reliability coefficient Dv output from the Dv table 66 is a reliability for calculating the reliability coefficient D. The reliability coefficient D calculated by the reliability coefficient calculation unit 67 is supplied to the multiplier 65 described above.
Here, the Dv table 66 is constituted by a table having the vehicle speed detection value Vs on the horizontal axis and the reliability coefficient Dv on the vertical axis, and the reliability coefficient Dv increases stepwise as the vehicle speed detection value Vs increases. A characteristic line is set.

  The reliability coefficient calculation unit 67 includes an adder 68 to which the reliability coefficient Db is input, a limiter 69 that limits the maximum value and the minimum value of the addition output of the adder 68 and outputs the reliability coefficient D, The delay unit 70 delays and holds the output of the limiter 69 as the previous reliability coefficient D (n-1), and the previous reliability coefficient D (n-1) output from the delay unit 70 is multiplied by a predetermined gain. A gain setting unit 71 is provided. The output of the gain setting unit 71 is output to the adder 68, and the reliability coefficient D output from the limiter 69 is output to the multiplier 65.

Further, the multiplication output of the multiplier 65 is supplied to the adder 72, and the previous value θc (n−1) of the neutral point estimated value θc, which is the addition output, is output to the adder 72 from the delay unit 73 that holds the delay. The previous neutral point estimated value θc (n−1) is input.
Then, the neutral point estimated value θc output from the adder 72 is supplied to the subtracter 74 as the straight steering relative steering angle θrn. The subtractor 74 is supplied with the neutral point provisional value θntemp calculated by the multiplier 37, and subtracts the neutral point provisional knowledge θntemp from the straight steering relative steering angle θrn to calculate the neutral point left-right difference θncom, The neutral point left / right difference θncom is updated and stored in a predetermined storage area of the nonvolatile memory 24.

According to the second embodiment, the neutral point left / right difference estimating unit 62 calculates the neutral point estimated value θc by executing the following equation (9).
θc = (θa−θc (n−1)) · D + θc (n−1) (9)
As the vehicle speed detection value Vs increases, the reliability coefficient Dv calculated by the Dv table 66 increases sequentially from “0” to “1”, “2”, “3”,.

For this reason, the reliability coefficient Dv becomes a large value in a state where the vehicle speed is high and the result of determining that the vehicle travels straight is continued, so the previous center point rudder angle θc (n−1) from the absolute rudder angle estimated value θa. ) Is subtracted from the corrected absolute steering angle estimated value by the reliability coefficient D, and the previous neutral point steering angle θc (n-1) is added to the multiplied value to calculate the neutral point steering angle estimated value θc. Therefore, the accurate neutral point rudder angle estimated value θc can be calculated. Accordingly, the calculated neutral point rudder angle estimated value θc can be used as the straight-direction relative rudder angle θrn, and the neutral point provisional value θntemp can be subtracted from the straight-direction relative rudder angle θrn to accurately calculate the neutral point left-right difference θncop. .
Since the neutral point provisional value θntemp is corrected based on the neutral point left / right difference θncop, the neutral point provisional value in which the neutral point deviation amount is accurately corrected can be calculated. The estimated value θa can be estimated more accurately.

In the first and second embodiments, the case where the absolute steering angle estimated value θa detected by the absolute steering angle calculation unit 26 is used by the handle return control unit 28 of the electric power steering apparatus has been described. It is not limited to the above, and it may be transmitted to other in-vehicle control devices such as a travel control device that requires the absolute steering angle estimated value θ using a network such as CAN, or may be directly transmitted. Good.
In the first and second embodiments, the case where the motor angle sensor 14 is applied when the relative steering angle θr is detected has been described. However, the present invention is not limited to this. You may make it apply the steering angle sensor comprised, for example with a photointerpreter, which detects a rotation angle.

1 is an overall configuration diagram showing a first embodiment of the present invention. It is a block diagram which shows the specific structure of the control apparatus 16 of FIG. It is a block diagram which shows the specific structure of the absolute steering angle calculating part of FIG. It is a flowchart which shows an example of the dead zone setting process procedure performed in the dead zone setting part of FIG. It is a characteristic diagram which shows the relationship between an absolute steering angle provisional value and an absolute steering angle estimated value. It is a block diagram which shows the specific structure of the handle | steering wheel return control part of FIG. It is a block diagram which shows the specific structure of the absolute steering angle calculating part which shows the 2nd Embodiment of this invention. It is a block diagram which shows a neutral point left-right difference calculation part.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Steering wheel, 2 ... Steering shaft, 12 ... Deceleration mechanism, 13 ... Electric motor, 14 ... Motor angle sensor, 15 ... Vehicle speed sensor, 16 ... Control apparatus, 19 ... Motor current detection circuit, 21 ... Current command value calculating part , 22 ... current feedback control unit, 23 ... motor drive circuit, 24 ... non-volatile memory, 26 ... absolute steering angle calculation unit, 27 ... differentiation circuit, 28 ... handle return control unit, 29 ... adder, 31 ... relative steering angle Arithmetic unit, 32... Maximum value calculating unit, 33... Minimum value calculating unit, 34, 35... Delayer, 36 adder, 37 .. Multiplier, 38 .. Subtractor, 30. Dead band setting unit, 40, 41. 42 ... multiplier, 43 ... adder, 60 ... self-aligning torque estimation unit, 61 ... straight-running state determination unit, 62 ... neutral point left / right difference estimation unit, 63a, 63b ... open / close switch, 64 ... subtractor 65 ... multiplier, 66 ... Dv table, 67 ... reliability calculation unit, 72 ... adder, 73 ... delay unit, 74 ... subtractor

Claims (5)

Relative steering angle detection means for detecting the relative steering angle θr of the steering mechanism of the vehicle, total steering angle range storage means for storing the known vehicle total steering angle range θt, and the total steering angle range storage means stored in the total steering angle range storage means Absolute steering angle estimated value calculating means for calculating an absolute steering angle estimated value θa of the steering mechanism based on a vehicle total steering angle range θt and the relative steering angle θr detected by the relative steering angle detecting means ;
The absolute rudder angle estimated value calculation means is
Regarding the relative rudder angle θr with a positive / negative sign during steering, the maximum value θrmax of the relative rudder angle θr that is maximum when the positive direction is large and the negative direction is small, and the positive direction is large and the negative direction is A steering range detecting means for detecting a minimum value θrmin of the relative steering angle θr that is minimum when it is small;
Based on the maximum value θrmax and minimum value θrmin detected by the steering range detection means and the vehicle total steering angle range θt, the maximum value θnmax and the minimum value θnmin of the neutral point existence steering angle range where the neutral point of the steering angle exists. A midpoint rudder angle range computing unit that computes a midpoint rudder angle range θnrange based on the estimated maximum value θnmax and minimum value θnmin and the vehicle total rudder angle range θt;
An absolute rudder angle calculation unit that calculates an absolute rudder angle estimated value θa based on the maximum value θnmax and the minimum value θnmin of the midpoint rudder angle range calculated by the midpoint rudder angle range calculation unit. A steering angle detection device for a vehicle. The midpoint rudder angle range calculation unit is based on the maximum value θrmax and the minimum value θrmin of the relative rudder angle θr and the vehicle total rudder angle range θt,
θnmax = (θrmax + θrmin) / 2 + {θt− (θrmax−θrmin)} / 2
θnmin = (θrmax + θrmin) / 2− {θt− (θrmax−θrmin)} / 2
θrange = θnmax−θnmin
The vehicle steering angle detection device according to claim 1 , wherein the neutral point steering angle range θrange is calculated by performing the following calculation. When the total steering angle range θt is asymmetrical with respect to the neutral point, the neutral point left / right difference estimating means for estimating the neutral point left / right difference θncop by straight traveling determination, and the neutral point estimated by the neutral point left / right difference estimating means A neutral point provisional value correction means for correcting a neutral point provisional value θntemp which is an average value of the maximum value θrmax and the minimum value θrmin of the relative steering angle θr based on the right / left difference θncop, and the neutral point left / right difference θncop Neutral point left / right difference storage means stored in the vehicle, and neutral point steering angle initial correction means for correcting the neutral point provisional value θntemp based on the neutral point left / right difference θncop stored in the nonvolatile memory when the vehicle is started. provided by and be a vehicle steering angle detector according to claim 1 or 2, characterized in. A dead zone setting means for setting an absolute rudder angle dead zone for the absolute rudder angle estimated value θa based on the neutral point rudder angle range θrange is provided, and the absolute rudder angle estimating unit includes the relative rudder angle θr, the neutral point rudder angle range θnrange and the vehicle steering angle detecting device according to any one of claims 1 to 3, characterized in that absolute configured to estimate an absolute steering angle estimated value θa based on the steering angle deadband . It provided a vehicle steering angle detecting device according to any one of claims 1 to 4, and performs a steering control based on the absolute steering angle of the steering wheel detected by the vehicular steering angle detector Electric power steering device.

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