0001]The present invention, the motor is driven and controlled by the current command value, the vehicle steering system relates to an electric power steering apparatus for assist control, in particular mounting at least two angle sensors to the steering shaft by the drive control of the motor, a gear therein there is an angle sensor via a mechanism, monitors and diagnostics by estimating the signals of the other angle sensors using the signal of the angle sensor learns the characteristics of the gear mechanism, through the learning result and the gear mechanism during normal , if the other angle sensor fails relates to an electric power steering device capable of backup by using the estimated signal.
Background technique
[0002]
　An electric power steering device for assisting control of the steering system of the vehicle in the rotational force of the motor (EPS) is a transmission mechanism such as gears or a belt via reduction gear by the driving force of the motor, the steering assist force to a steering shaft or a rack shaft It adapted to provide the (assist force). 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 the steering assist command value (current command value) and the motor current detection value to adjust the voltage applied to the motor so as to reduce, adjustment of the voltage applied to the motor, generally a PWM (Pulse Width It is carried out by adjusting the modulation) control duty.
[0003]
　To describe the general construction of an electric power steering apparatus shown in FIG. 1, column shaft of the handle 1 (steering shaft, the steering wheel shaft) 2 is a reduction gear 3, universal joints 4a and 4b, a pinion rack mechanism 5, tie rods 6a, through 6b, it is connected further hub unit 7a, via 7b steering wheels 8L, the 8R. In addition, the column shaft 2, a steering angle sensor 14 for detecting the torque sensor 10 and the steering angle θ for detecting the steering torque of the steering wheel 1 is provided, the motor 20 is a reduction gear 3 for assisting the steering force of the steering wheel 1 It is connected to the column shaft 2 via the. 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 the voltage control command value Vref subjected to, for controlling a current to be supplied to EPS motor 20.
[0004]
　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.
[0005]
　Control unit 30 mainly MCU consists of (CPU, including MPU), it is shown in Figure 2 when showing a general function executed by a program in the MCU internal.
[0006]
　To explain the function and operation of the control unit 30 with reference to FIG. 2, which is detected by the steering torque Th and the vehicle speed sensor 12 detected by the torque sensor 10 (or from CAN40) vehicle speed Vel is a current command value Iref1 is input to the current command value calculation unit 31 for calculating. Current command value calculating section 31 uses the assist map or the like based on the input steering torque Th and the vehicle speed Vel, it calculates a current command value Iref1 is a control target value of the current supplied to the motor 20. The current command value Iref1 is inputted to the current limiting unit 33 via the adder portion 32A, the current command value Irefm which is limiting the maximum current is inputted to the subtraction unit 32B, the deviation I (Irefm the motor current value Im that is fed back -im) is calculated, the deviation I is inputted to a PI (proportional integral) control unit 35 for improving the characteristics of the steering operation. Voltage control command value Vref which is characteristic improvement by the PI control unit 35 is inputted to a PWM control unit 36, the motor 20 is PWM driven further via the inverter 37 as a drive unit. Current value Im of the motor 20 is detected by a motor current detector 38 and fed back to the subtraction section 32B. Inverter 37 is a FET (field effect transistor) is used as a driving element, and a bridge circuit of the FET.
[0007]
　The addition unit 32A are subject to compensation signal CM from the compensation signal generation unit 34 performs characteristic compensation of the steering system based by the addition of the compensation signal CM, it is adapted to improve the convergence and inertial characteristics . Compensation signal generation unit 34, the self-aligning torque (SAT) 343 and the inertia 342 are added in the addition unit 344, further by adding the convergence 341 by an adder 345 to the addition result, compensating the addition result of the adder 345 It is a signal CM.
[0008]
　The electric power steering system as described above, in recent years, from the reliability and operability improved and functional requirements of redundancy, etc., may be mounted by multiplexing sensors. However, since there is also a need in cost reduction and miniaturization of the electric power steering apparatus, it is not easy to multiplex multiple sensors. Therefore, by utilizing the sensor limited which is currently mounted to the maximum, method that allows monitoring diagnostic sensor together it is desirable. However, depending on the mounting position of the sensor might be via a gear, in which case, in order to monitor and diagnose sensor each other it is necessary to reduce the influence of the backlash of the gear.
[0009]
　As prior art, WO 2004/022414 (Patent Document 1) discloses a method for measuring the torque for a vehicle having an electromechanical steering system, considered as a backup of the torque sensor ing. The overall structure, the connected input shaft and an output shaft portion driven steering mechanism, an electromechanical steering device and a steering means connected via a torsion bar having a servo motor. Its structure, the relative rotational displacement between the input shaft and an output shaft of the driving steering mechanism, although it is electromechanical steering system for performing torque detection (digital circuit or analog circuit), the steering angle ([delta]) sensor in the output and second input of the rotation angle of the servo motor, forms a sensor for detecting a virtual torque, the steering torque is determined from the virtual torque.
[0010]
　Further, in JP 2005-274484 (Patent Document 2), a plurality (three) of the steering angle sensor is mounted to a redundant system.
CITATION
Patent Document
[0011]
Patent Document 1: WO 2004/022414 Patent
Patent Document 2: JP 2005-274484 JP
Summary of the Invention
Problems that the Invention is to Solve
[0012]
　However, in the apparatus of Patent Document 1, the system of the backup against failure of the steering angle sensor, it can be backed up by the rotor rotation information of the servo motor, and mutual fault diagnosis for both sensors backup it is impossible. Further, in the example of Patent Document 2, since the steering system around becomes large, the vehicle mountability becomes worse devices, generally there is a cost problem.
[0013]
　The present invention has been made in view of the above described circumstances, an object of the present invention, a plurality of angle sensors in addition to the angle sensor through the gear mechanism is mounted to the steering shaft, to learn the characteristics of the gear mechanism , monitors and diagnosed by estimating the signals of the other angle sensors using the signal of the angle sensor through the learning result and the gear mechanism, without further multiplexing angle sensor for backup can back up It is to provide an inexpensive and high-performance electric power steering apparatus according to.
Means for Solving the Problems
[0014]
　The present invention includes a first angle sensor for detecting a first steering angle via the gear mechanism relates to an electric power steering apparatus characterized by at least a second angle sensor for detecting a second steering angle without passing through the gear mechanism the object of the present invention, a corrective offset calculation unit for calculating a corrective offset to learn the characteristics of the gear mechanism, a steering angle estimating section for estimating the second steering angle using the correction offset It is achieved by providing a.
[0015]
　The above object of the present invention, the first steering angle and the second steering angle including a relative steering angle section for relative steering angle of the correction offset calculation section, first steering which is the relative steering angle of by calculating the correction offset based on the corner and the second steering angle, or with the steering judging portion determines the steering direction, the correction offset calculation unit, the correction corresponding to the determined steering direction by calculating the use offsets, or the second angle sensor has become a multi-system, if one system of the second angle sensor fails, using the measured values ​​and the estimated value of the second steering angle the by and performs the backup of the second angle sensor, or based on the measured value and the estimated value of the second steering angle, by performing the monitoring and diagnosis of the second angle sensor, or the correction offset Calculation unit, by calculating a correction offset to learn the deviation of the first steering angle and the second steering angle, or the correction offset calculation unit is within range of an angle period of the first angle sensor in learning a plurality of the deviation calculated at predetermined intervals, the average value of the plurality of deviations learned that with the correction offset, or the first angle sensor and the second angle sensor steering by being mounted on the input shaft side of the shaft, it is more effectively achieved.
Effect of the invention
[0016]
　According to the electric power steering apparatus according to the present invention, the characteristics of the gear mechanism when the angle sensor is operating normally, learning the backlash component, especially by the steering direction, to calculate a corrective offset, via a gear mechanism angle by using the signal for correction the offset of the sensor can monitor and diagnose by estimating the signals of the other angle sensors, in the case where other angles sensor fails can be backed up.
BRIEF DESCRIPTION OF THE DRAWINGS
[0017]
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.
3 is a block diagram showing an arrangement example of an angle sensor of the present invention.
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 judging portion according to the present invention.
6 is a diagram showing an example of a learning point.
Is a block diagram showing a configuration example of the correction offset calculation section according to FIG. 7 present invention.
Is a flowchart showing an operation example of FIG. 8 the invention.
Is a flowchart showing an operation example of FIG. 9 relative steering angle of.
Is a flowchart showing an operation example of FIG. 10 steering determination.
11 is a diagram showing changes in the steering determination according to the invention.
Is a flowchart showing an operation example of FIG. 12 corrective offset calculation.
13 is a diagram showing changes in estimated by correcting the offset used according to the invention.
DESCRIPTION OF THE INVENTION
[0018]
　The present invention is mounted a plurality of angle sensors on the steering shaft, if there is an angle sensor for detecting a steering angle (first angle sensor) via a gear mechanism therein, to learn the characteristics of the gear mechanism , using the steering angle learning result and the first angle sensor detects (steering angle signal), other angle sensors (second angle sensor) to estimate the steering angle to be detected. Usually, steering angle to gear backlash (backlash) is present so that it can move freely, the steering angle of the first angle sensor by the backlash is detected (first steering angle) of the second angle sensor for detecting since errors (second steering angle) (deviation) occurs in the present invention learns the backlash component is a characteristic of the gear mechanism in order to reduce the influence of the backlash. Learned by calculating a corrective offset, by the first steering angle is corrected by the correction offset, estimating a second steering angle. Then, the monitoring and diagnosis of the second angle sensor by using the estimated steering angle, if the second angle sensor is a dual system is one system failure (hereinafter, including "abnormal") so that the can back up upon.
[0019]
　Hereinafter, the embodiments of the present invention will be described with reference to the drawings.
[0020]
　In the present embodiment, as shown in FIG. 3, the angle sensor is mounted on the second steering shaft (handle shaft), various detection signals are outputted. That is, the steering wheel shaft 2 of the steering wheel 1 side of the input shaft (input shaft) 2A, a torque sensor input side rotor, which is one angle sensor of the torque sensor consists of an angle sensor of the Hall IC sensor 21 and the pair 20 ° the rotor sensor 22 is mounted. Hall IC sensor 21 is mounted to the input shaft 2A through gears, the rotation of the input shaft 2A detected in 296 ° cycle, and outputs the AS_IS angle [theta] h. A torque sensor is a double line, 20 ° rotor sensor 22 mounted directly to the handle 1 side from the torsion bar 23 the rotation of the input shaft 2A detected in 20 ° cycle, outputs TS_IS angle θs1 and θs2 while, TS_IS angle θs1 and θs2 are input to the steering angle calculation unit 50. Further, the output shaft (output shaft) 2B of the handle shaft 2, 40 ° rotor sensor 24 of the torque sensor output side rotor is the other of an angle sensor of the torque sensor is mounted directly, 40 ° rotor sensor 24 the rotation of the output shaft 2B detected by the 40 ° period, and outputs the TS_OS angle θr1 and θr2, TS_OS angle θr1 and Shitaaru2 are input to the steering angle calculation unit 50. Steering angle calculating unit 50 calculates the relative displacement of TS_IS angle θs1 and TS_OS angle .theta.R1, it outputs a twist angle Shitati1, likewise calculates the relative displacement of TS_IS angle θs2 and TS_OS angle Shitaaru2, outputs the twist angle θt2 . Steering torque is calculated based on the twist angle θt1 and Shitati2.
[0021]
　In the present embodiment, the Hall IC sensor 21 is the first angle sensor, 20 ° rotor sensor 22 corresponds to a second angle sensor, the first steering angle AS_IS angle θh of the Hall IC sensor 21 outputs, 20 ° rotor TS_IS angle θs1 and? s2 sensor 22 outputs (hereinafter collectively θs1 and? s2 is "θs", "θs" is intended to mean a θs1 or? s2) corresponds to a second steering angle. AS_IS angle θh and TS_IS angle θs1 and θs2 are input to the control unit (not shown). Although inputted to also the control unit steering angle θt1 and θt2 twisted TS_OS angle θr1 and θr2 arrangement, since not directly related to the present invention, the description thereof is omitted.
[0022]
　In such a configuration, in order to perform the TS_IS angle θs backup is the second steering angle using the AS_IS angle θh is the first steering angle, the difference in angle cycle of the Hall IC sensor 21 and 20 ° rotor sensor 22 , it is necessary to estimate the TS_IS angle θs in consideration of backlash influence of the difference and gear angular reference point.
[0023]
　The differences of angle period, handle AS_IS angle θh and TS_IS angle θs as steering wheel angle, i.e., corresponding by relative steering angle of. Depending on the performance of the angle sensor, if necessary, keep removing noise by using a filter on AS_IS angle θh and TS_IS angle [theta] s.
[0024]
　The differences and the influence of gear backlash angle reference point, the error of TS_IS angle θs and AS_IS angle θh that is relative steering angle of when the torque sensor is a double system is operating properly together in, above learning to calculate the correction offset as corresponding by correcting the AS_IS angle θh by the corrective offset. Corrective offset is calculated in accordance with the steering direction, the left switch steering Specifically, the correction offset of the three patterns of the right changeover steering and steering holding is calculated, a gear by selectively using the correction offset in accordance with the steering situation reduce the impact to the error of by the backlash.
[0025]
　It shows a configuration example of a control unit implementing such a function in Fig.
[0026]
　AS_IS angle θh and TS_IS angle θs is input to the control unit are input to the relative steering angle section 60, the relative steering angle section 60, the relative steering angle of been AS_IS angle (hereinafter, the "AS_IS relative steering angle" to) Shitahr and relative steering angle of been TS_IS angle (hereinafter referred to as "TS_IS relative steering angle") to the Shitasr. AS_IS relative steering angle θhr steering determining unit 70, is input to the correction offset calculation unit 80 and the steering angle estimating portion 100, TS_IS relative steering angle θsr is inputted to the correction offset calculation unit 80. Steering determining unit 70 determines the steering status (left off / right switching / steering holding), and outputs the determination result Sj, the determination result Sj is input to the correction offset calculation unit 80 and the steering angle estimating portion 100. Corrective offset calculating section 80, AS_IS relative steering angle Shitahr, from TS_IS relative steering angle θsr and determination result Sj, corrective offset of the left changeover steering (hereinafter referred to as "left Setsuji offset") Csl, right off the steering corrective offset in (hereinafter referred to as "Migisetsuji offset") Csr and corrective offset at the time of steering hold (hereinafter referred to as "Hokajiji offset") seek Csk. Corrective offset (left Setsuji offset Csl, Migisetsuji offset Csr, Hokajiji offset Csk) is stored in the correction offset storage unit 90. Steering angle estimating portion 100, AS_IS relative steering angle Shitahr, determination result Sj and TS_IS relative steering angle estimated from corrective offset that is stored in the correction offset storage section 90 (hereinafter referred to as "TS_IS estimated steering angle") and it outputs the θse.
[0027]
　The following describes each part.
[0028]
　Relative steering angle section 60, in order to eliminate the difference in angle period of AS_IS angle θh and TS_IS angle [theta] s, these angles a (angle signal) to the anti-rollover treated as a relative steering angle. Apply the same procedure for AS_IS angle [theta] h and TS_IS angle [theta] s, the input angle (AS_IS angle [theta] h, TS_IS angle [theta] s) and the input angle and the difference between the last time (one sample before) (hereinafter referred to as "angular difference") addition angle (hereinafter, "addition angle" to) based on the decided, accumulated from the addition beginning summation angle (hereinafter, "cumulative addition angle" to) relative steering angle is added to the input angle ( AS_IS relative steering angle Shitahr, by obtaining the TS_IS relative steering angle θsr), performs a relative steering angle of. Specifically, the maximum value of the input angular input angle range (hereinafter referred to as "angle maximum value") If lower than 1/2, i.e., -1/2 times smaller than the angular difference angle maximum when the addition angle is the angle the maximum value, when the input angle increases than half the angle the maximum value, i.e., if the angle difference is 1/2 times larger than the angle the maximum value, the addition angle is the angle the maximum value × ( -1), and otherwise, adding the angle is 0. Also, when removing noise superimposed on the input angle, it performs a filtering process on the relative steering angle.
[0029]
　Steering determining unit 70 determines the steering status to selectively use the correction offset in accordance with the steering situation. (In this embodiment the Hall IC sensor 21) the angle sensor in order to correct the backlash components of the gear is required direction of rotation of the information of the gear, the rotational direction of the gears can be determined from the steering direction, the steering judging portion 70 Te steering situation (left off / right off / steering holding) judges. Determination of the steering situation by providing a hysteresis characteristic to AS_IS relative steering angle Shitahr, i.e., carried out by providing a predetermined hysteresis width AS_IS relative steering angle Shitahr. By providing a hysteresis characteristic, it is possible to reduce the influence of the steering state determination due to noise. Upper limit value obtained by subtracting a predetermined value to AS_IS relative steering angle θhr inputted (hereinafter referred to as "steering angle limit value") is set as the lower limit value obtained by adding a predetermined value from AS_IS relative steering angle θhr value (hereinafter referred to as "steering angle limit value") is set as the difference between the steering angle limit value and the steering angle limit value is hysteresis width. Then, the steering angle limit value and the steering angle limit value and the center value of the hysteresis width (hereinafter referred to as "hysteresis center value") and the value of the previous (one sample before) (hereinafter referred to as "hysteresis center previous value") by comparison, updating the hysteresis center value. Specifically, when the steering angle limit value is greater than the hysteresis center previous value, the steering angle limit value and hysteresis center value, when the steering angle limit value is less than the hysteresis center previous value, the steering angle limit value and hysteresis center value , otherwise, update of the hysteresis center value is not performed. Then, the steering direction is determined by comparing the AS_IS relative steering angle θhr hysteresis center value, further, considered as fixed steering the case where hysteresis center value is not changed for a certain time. That is, when AS_IS relative steering angle θhr is smaller than the hysteresis center value, right off the steering tentatively determined (hereinafter, this determination result is "provisional decision result"), AS_IS relative steering angle θhr is above the hysteresis central value If so, tentatively determined that the left switch steering, otherwise (i.e., if the same AS_IS relative steering angle θhr is a hysteresis central value), before And rotating the provisional decision result provisional determination result of the case where the hysteresis center value is not changed for a certain time, the determination result Sj as the steering holding, if not, the determination result Sj provisional determination results. Incidentally, the hysteresis width is set to a size capable of removing noise components of the angular sensor, the time interval for determining a steering hold is set so as not to erroneously determined steering hold when the slow steering.
[0030]
　A configuration example of a steering judging portion 70 shown in FIG. Hysteresis width setting unit 71 to have a predetermined hysteresis width AS_IS relative steering angle Shitahr, and outputs a steering angle upper limit θ1 and the steering angle limit value .theta.2. Hysteresis central value calculating unit 72 updates the hysteresis center value by comparing the hysteresis precentral value θcp held in steering angle upper limit θ1 and the steering angle limit value θ2 and the memory unit 75, outputs a hysteresis center value θc to. Hysteresis center value θc is is held in the memory unit 75, is input to the steering direction determination unit 73 and the maintenance determination unit 74. Steering direction determining unit 73 a steering direction determined by comparison with AS_IS relative steering angle θhr hysteresis center value .theta.c, and outputs the provisional judgment result Sd. Maintenance determination unit 74 determines whether the steering hold based on the hysteresis center value θc and hysteresis precentral value Shitacp, determines the judgment result as the provisional decision result Sd from the determination result Sj, and outputs.
[0031]
　Corrective offset calculation unit 80, the difference in TS_IS relative steering angle θsr and AS_IS relative steering angle θhr when torque sensor double system is operating normally (hereinafter referred to as "relative steering angle difference") learn and, to calculate the correction for the offset. To play the clogging degree becomes indefinite at the difference between the simple TS_IS relative steering angle and AS_IS relative steering angle, the learning is carried out in both directions of the left changeover steering and right switching steering. In addition, in order to avoid the erroneous learning, steering speed at the time of learning is carried out in the state that have come up with a constant speed not too fast not too slow (a state in which clogged backlash). For too slow steering speed, for example, in order to play the state becomes unstable in the steering holding state, the possibility of erroneous learning is increased. For too fast steering speed, data (AS_IS angle [theta] h, TS_IS angle [theta] s) by the inertia, etc. of the gear error and gears of the timing of acquiring, it becomes likely to also erroneous learning. Furthermore, even in appropriate steering speed, when the speed variation (acceleration) is large, there is a high possibility that erroneous learning, the steering speed is conducted only learning in a stable state. Further, since the backlash component varies with the combination of gears of the gear, but the number of samples to be learned is often more desirable, since it is necessary to suppress the information amount of the relative steering angle difference to be used for learning, and the sample at appropriate intervals to use the data. In this embodiment, increment angle cycle of the Hall IC sensor 21 (296 °) at 10 ° ± 1 °, learns the relative steering angle difference in both the left switch steering and right switching steering at each increment point, total 60 It performs learning at the point (hereinafter referred to as "learning points" a point to perform learning). 6 is a diagram showing an example of a learning point. The horizontal axis in AS_IS relative steering angle, and the vertical axis in a relative steering angle difference, shows a change in the relative steering angle difference in a case where the left switch steering and right switching steering a solid line. Then, it shows part of the learning point in broken lines shows an steering direction of the sample data in the learning point circle. Obtaining sample data by the learning points as shown in Figure 6. Then, an average of 30 learning points of the learning result of the left changeover steering the left Setsuji offset Csl, 30 learning port of the right changeover steering The average of the points for learning results and right Setsuji offset Csr, the average of the left Setsuji offset and Migisetsuji offset the steering hold time offset Csk. As a learning result at each learning point, it is also possible to use average value calculated from a plurality of sample data, in the present embodiment, uses only one sample data. The learning point is not limited to 60 points above, at a set point in another step size and variable step sizes, etc. may be performed learning. Further, the left Setsuji offset and Migisetsuji offset is not a mean value of a plurality of learning result, or in the mode or median, or the like.
[0032]
　A configuration example of the correction offset calculation unit 80 shown in FIG.
[0033]
　Steering speed calculating section 81 calculates the steering speed Omegahr than AS_IS relative steering angle Shitahr, steering acceleration calculating unit 82 calculates the steering acceleration αhr than the steering speed Omegahr, steering speed Omegahr and steering acceleration αhr the gear characteristic learning unit 83 It is input to. The gear characteristic learning unit 83, in addition to the steering speed ωhr and steering acceleration Arufahr, AS_IS relative steering angle Shitahr, the determination result Sj outputted from TS_IS relative steering angle θsr and steering determining section 70 are input.
[0034]
　Gear characteristic learning unit 83 performs learning using the relative steering angle difference Rs (= TS_IS relative steering angle θsr-AS_IS relative steering angle θhr). First, it AS_IS relative steering angle θhr and TS_IS relative steering angle θsr is data available for learning, determined by using a steering speed ωhr and steering acceleration Arufahr. That is, the steering speed ωhr is the velocity of the appropriate range, and not larger absolute value of the steering acceleration αhr is, that the state where the steering speed is and stable without too early nor too late, it is determined that they can be used for learning . If it is determined that can be used for learning, judgment result Sj performs the learning of as a learning point of the left switch steering the case of the "left off", the judgment result learning of Sj is right off the steering in the case of "right off" You learn as a point, if the determination result Sj is "holding" does not perform learning. Relative steering angle difference Rs is held in the learning result holding unit 84 as the learning results at each learning point. Upon holding the relative steering angle difference Rs, it is necessary to identify the learning point or a learning result for any learning points, learning point AS_IS relative angular spacing the movable range fixed θhr WD (e.g. 10 °) a point chopped, always if possible to acquire data at the same point, using as the value of AS_IS relative angle Shitahr, can identify the learning point. However, in practice to obtain the data is always at the same point is difficult, since the value of AS_IS relative angle Shitahr resulting in blurring, to identify the learning points by processing the AS_IS relative angle Shitahr. Specifically, for example, a value sp calculated from the following equation 1.
[0035]
[Number

1] Kp is the number of learning points set in one steering direction (e.g. 30), ROUND (x) is a function that returns a value obtained by rounding off the decimal point x, mod is the case, the A (A mod B) an operator for calculating a remainder (remainder) divided by B. The sp, used as an identifier for identifying each learning point, the steering direction (the left switch, right switch) in the area learning result holding unit 84 for holding a relative steering angle difference Rs for each value of another identifiers sp provided, continue to hold the relative steering angle difference Rs based on the steering direction and identifier sp. For example, WD = 10 °, in the setting of Kp = 30, when the value of AS_IS relative angle θhr is 123 ° in the left switch steering, sp = 12, and the relative steering angle difference Rs at this time, left off value There is maintained in the region for the identifier sp 12. It is also possible to identify the learning point in any other way.
[0036]
　After learning in all learning point complete, using the relative steering angle difference Rs held in the learning result holding unit 84, the correction offset (left Setsuji offset Csl, Migisetsuji offset Csr, Hokajiji offset Csk) is calculated.
[0037]
　Correction offset is stored in the correction offset storage unit 90, backup becomes possible from the stage of Motoma' correction offset.
[0038]
　Steering angle estimating portion 100 in accordance with the determination result that is output from the steering judging portion 70 (left off / right switching / steering holding), select the corrective offset that is stored in the correction offset storage unit 90, AS_IS by adding the correction offset relative steering angle Shitahr, seek TS_IS estimated steering angle Shitase.
[0039]
　In such a configuration, first the entire operation example will be described with reference to the flowchart of FIG.
[0040]
　TS_IS angle θs detected by AS_IS angle θh and 20 ° rotor sensor 22 detected by the Hall IC sensor 21 is input to the relative steering angle section 60 (step S10). Relative steering angle of section 60 relative steering angle of the AS_IS angle [theta] h (step S20), and outputs the AS_IS relative steering angle Shitahr, relative steering angle of the TS_IS angle [theta] s (step S30), TS_IS relative steering angle θsr to output. It will be described later operation of the relative steering angle of. The order of the relative steering angle of AS_IS relative steering angle of the angle θh and TS_IS angle θs may be reversed. If steering determination unit 70 uses the AS_IS relative steering angle θhr outputted from the relative steering angle section 60 determines the steering status, if it is determined that the left switch steering the determination "left off", the right switch steering the "right off", if it is determined that the steering hold state and outputs a determination result Sj that the "holding" (step S40). It will be described later operation of the steering decision. When the learning of the relative steering angle difference is not completed (step S50), the correction for offset calculation unit 80, AS_IS relative steering angle θhr and TS_IS relative steering angle θsr and steering output from the relative steering angle section 60 performs a learning operation of the backlash components of the gear by using a determination result Sj outputted from the determination unit 70 (step S60), the flow returns to step S10. Will be described later, the operation of learning. If the learning has been completed (step S50), the left Setsuji offset Csl, since Migisetsuji offset Csr and Hokajiji offset Csk is stored in the correction offset storage unit 90 as a correction offset, steering angle estimating parts 100 checks the judgment result Sj outputted from the steering determination unit 70 (step S70), the determination result when Sj is "left off" in AS_IS relative steering angle θhr outputted from the relative steering angle section 60 calculates the TS_IS estimated steering angle θse by adding the left Setsuji offset Csl stored in the correction offset storage unit 90 (step S80). If the determination result Sj is "right off", the AS_IS relative steering angle Shitahr, the right switching time offset Csr stored in the correction offset storage unit 90 pressurized Calculated for calculating the TS_IS estimated steering angle θse by (step S90). If the determination result Sj is "holding", the AS_IS relative steering angle Shitahr, calculates the TS_IS estimated steering angle θse by adding a fixed steering time offset Csk stored in the correction offset storage unit 90 (step S100 ). Note that whether learning has been completed, to the correction offset correction offset storage unit 90 may be determined by whether it is stored, you may be notified by using a flag or the like .
[0041]
　An operation example of the relative steering angle of a relative steering angle section 60 will be described with reference to the flowchart of FIG. Incidentally, since the operation of the relative steering angle of AS_IS relative steering angle of the angle θh and TS_IS angle θs is the same, in the following description, use the expression "input angle" instead of AS_IS angle θh and TS_IS angle θs to. Further, when the operation start, and set to 0 as an initial value of the cumulative addition angle as the initial value of the input angle of the last (previous sample) using the same value as the current (current sample).
[0042]
　The relative steering angle of, calculates an angle difference by subtracting the input angle of the last from the first input angle (step S210). Since the input angle is used for the next relative steering angle of and held to the relative steering angle section 60. Then, the calculated angular difference is smaller than -1/2 times the angle the maximum value (step S220), the angle the maximum value and adding the angle (step S230). If the angle difference is greater than -1/2 times the angle the maximum value, compares the half the angular difference and the angle the maximum value (step S240), if the angle difference is 1/2 times larger than the angle the maximum value , and the angle the maximum value × (-1) the addition angle (step S250), if the following half of the angular difference angle maximum value, the addition angle is zero (step S260). Determined sum angle is added to the cumulative addition angle (step S270). The relative steering angle by adding cumulative addition angle to an input angle (AS_IS relative steering angle θhr, TS_IS relative steering angle Shitasr) is calculated (step S280). It performs a filtering process on the relative steering angle for noise removal (step S290), and outputs. The filter processing may be performed if necessary, it may not be executed.
[0043]
　An example of the operation of the steering judgment by the steering judging portion 70 will be described with reference to the flowchart of FIG. 10.
[0044]
　The steering determination, first, the hysteresis width setting unit 71, the relative steering angle unit a predetermined value on the output AS_IS relative steering angle θhr from 60 (hereinafter referred to as "hysteresis width") by subtracting the Rh steering angle upper limit θ1 (= θhr-Rh) was calculated (step S410), by adding the hysteresis range Rh from AS_IS relative steering angle Shitahr calculates the steering angle limit value θ2 (= θhr + Rh) (step S415). The order of calculation of the calculation and the steering angle limit value θ2 of the steering angle limit value θ1 may be reversed. Steering angle upper limit θ1 and the steering angle limit value θ2 is input to the hysteresis central value calculating section 72, the hysteresis central value calculating section 72, a hysteresis precentral value θcp held in steering angle upper limit θ1 and memory unit 75 comparison (step S420), the steering angle limit value .theta.1 may hysteresis centered greater than the previous value Shitacp, the hysteresis center value θc and the steering angle limit value .theta.1 (step S425). If the steering angle limit value θ1 is less hysteresis precentral value Shitacp, compares the steering angle limit value θ2 and hysteresis precentral value Shitacp (step S430), if the steering angle limit value θ2 hysteresis precentral value Shitacp smaller, hysteresis central value .theta.c the steering angle limit value .theta.2 (step S435), if the steering angle limit value .theta.2 hysteresis precentral value Shitacp above, updating of the hysteresis center value is not performed, the hysteresis center value hysteresis precentral value Shitacp .theta.c and it made (step S440). The average in the case of data calculated from the first AS_IS relative steering angle θhr the steering angle limit value θ1 and the steering angle limit value .theta.2 is calculated at operation start time, the steering angle limit value θ1 and the steering angle limit value .theta.2 ( = (θ1 + θ2) / 2) is the hysteresis center value .theta.c. In the present embodiment, θ1 = θhr-Rh, because it is θ2 = θhr + Rh, the first hysteresis center value θc becomes the same value as AS_IS relative steering angle Shitahr. Hysteresis center value θc is is held as hysteresis precentral value θcp in the memory unit 75, is input to the steering direction determination unit 73 and the maintenance determination unit 74. Steering direction determination unit 73 inputs the AS_IS relative steering angle Shitahr, AS_IS relative steering angle Shitahr And comparing the hysteresis center value .theta.c, if AS_IS relative steering angle θhr hysteresis center value .theta.c smaller (step S445), the provisional judgment result Sd is "right off" (right off steering) (step S450), AS_IS relative steering If the angular θhr is greater than the hysteresis central value .theta.c (step S455), the provisional judgment result Sd is "left off" (left off steering) (step S460), if the same AS_IS relative steering angle θhr is a hysteresis centered value .theta.c, interim determination result Sd provisional decision result and the same of the previous (one sample before) (step S465). Preliminary determination result Sd is input to the maintenance determination unit 74 with hysteresis precentral value θcp held in the hysteresis center value θc and the memory unit 75. Maintenance determination unit 74 compares the hysteresis center value θc and hysteresis precentral value Shitacp, hysteresis center value θc and hysteresis precentral value Shitacp is the same value, and the same value in a state a predetermined time (e.g., 100ms (milli sec.)) If you continue (step S470), the judgment result Sj as a "holding" (step S475), otherwise, the judgment result Sj is the same as the provisional judgment result Sd (step S480), the output.
[0045]
　The manner of change in the steering determination above will be described with reference to FIG. 11. Figure 11 is an angle to the longitudinal axis, the horizontal axis as a time, a solid line a AS_IS relative steering angle, turn the hysteresis center value are those indicated by the broken line, the left turn off the handle to the right (left off steering) , change the after a while steering direction from the past on-center (the straight-ahead position) to the right (right off the steering), state of change when the steering direction was changed to the left from the past again on Center (left off steering) a represents.
[0046]
　The left switch steering, continue to increase AS_IS relative steering angle Shitahr, followed by state steering angle limit value θ1 to (= θhr-Rh) exceeds the hysteresis center previous value Shitacp, hysteresis center value θc is the steering angle limit value θ1 because it is updated, even hysteresis center value θc in accordance with the AS_IS relative steering angle θhr increases. During this time, AS_IS relative angle θhr is greater than the hysteresis center value .theta.c, since hysteresis center value .theta.c continues to change, the determination result is "left off". Thereafter, when the steering speed to change to the right off the steering becomes slow, becomes dull increased AS_IS relative steering angle Shitahr, large steering angle limit value θ1 is from hysteresis precentral value θcp no longer, further changes to the right off the steering, AS_IS relative steering angle Shitahr is started to decline, so the hysteresis center value θc at time t1 when the steering angle limit value θ2 (= θhr + Rh) falls below the hysteresis precentral value θcp changes the steering angle limit value .theta.2, hysteresis center value θc is AS_IS greater than the relative steering angle Shitahr. Therefore, the determination result is "right off" and while continues the state in which the steering angle limit value θ2 by lower AS_IS relative steering angle θhr is below the hysteresis center previous value Shitacp, hysteresis center value θc is the steering angle limit value θ2 update since the, it decreases in accordance with the AS_IS relative steering angle Shitahr. During this time, AS_IS relative angle θhr is smaller than the hysteresis center value .theta.c, since hysteresis center value .theta.c continues to change, the judgment result is followed by the "right off". Thereafter, when changes to the left off the steering again, AS_IS relative steering angle θhr is started to increase, since the hysteresis center value θc at time t2 the steering angle limit value θ1 exceeds the hysteresis precentral value θcp changes the steering angle limit value θ1 , hysteresis center value θc becomes smaller than AS_IS relative steering angle Shitahr, the decision result is "left off".
[0047]
　In the above steering determination, although the calculation of the steering angle limit value θ1 and the steering angle limit value θ2 are using the same hysteresis width may be used hysteresis width value is different.
[0048]
　An operation example of the learning of the correction for the offset calculation unit 80 will be described with reference to the flowchart of FIG. 12.
[0049]
　In the learning, first relative steering angle section AS_IS relative steering angle θhr output from 60 is the steering speed calculator 81 and the gear characteristic learning unit 83, TS_IS relative steering angle θsr are input to the gear characteristic learning section 83 ( step S610). Steering speed calculating section 81 calculates the steering speed ωhr than AS_IS relative steering angle Shitahr, and outputs to the steering acceleration calculator 82 and the gear characteristic learning unit 83 (step S620). Steering acceleration calculating unit 82 calculates the steering acceleration αhr than the steering speed Omegahr, and outputs to the gear characteristic learning unit 83 (step S630).
[0050]
　Gear characteristic learning unit 83, the steering speed ωhr is at a predetermined speed Hω (> Lω) below a predetermined speed Eruomega above, and when the absolute value of the steering acceleration αhr is less than a predetermined value H-alpha (step S640), it can be learned as proceed to the next step, if not, exit the behavior of learning. If possible learning, using AS_IS relative angle Shitahr, obtains an identifier sp than the number 1 identifies the learning point (step S650), further inputs the output determination result Sj from the steering determining unit 70 (step S660) . If the determination result Sj is "left off" (step S670), the learning of the learning point corresponding to the identifier sp in the left switch checks whether unlearned (step S680). If not learned, calculates a relative steering angle difference Rs subtracts the AS_IS relative steering angle θhr from TS_IS relative steering angle Shitasr (step S690), and outputs the learning result storage unit 84 (step S700), if the learned , both steps are skipped. If the determination result Sj is "right off" (step S670), the learning of the learning point corresponding to the identifier sp in the right switch to confirm or not the learning (step S710). If not learned, calculated similarly to the case relative steering angle difference Rs "left off" (step S720), and outputs the learning result storage unit 84 (step S730), if learned, both steps are skipped . If the determination result Sj is "holding" (step S670), the learning is not performed. Then, when all of the learning completed (step S740), among the relative steering angle difference Rs held in the learning result holding unit 84, calculates the average of the relative steering angle difference Rs of the learning points of the left switch, left output as Setsuji offset Csl (step S750). Similarly, calculate the mean of the relative steering angle difference Rs of the learning points of the right switching outputs as Migisetsuji offset Csr (step S760). The order of the calculation of the calculation and Migisetsuji offset Csr of the left Setsuji offset Csl may be reversed. After both offset calculation, calculate the average of the left Setsuji offset Csl and Migisetsuji offset Csr, outputs as Hokajiji offset (step S770). Left Setsuji Oh Offset Csl, Migisetsuji offset Csr and Hokajiji offset is stored in the correction offset storage unit 90 (step S780), the learning completion. Incidentally, the presence or absence of learning in each learning point to the relative steering angle difference Rs in the learning result storage unit 84 may be judged by whether stored separately prepared flags in the learning result holding unit 84 , may be using it.
[0051]
　The manner of change of the estimated by the correction offset used is shown in Figure 13. 13 vertical axis angle, the horizontal axis as a time, by a one-dot chain line TS_IS relative steering angle, which shows the TS_IS estimated steering angle by a solid line, steering the right switch steering → steering holding → left off steering handle it represents the state of a change in the case of. As described above, TS_IS estimated steering angle θse is calculated by adding the determination result corrective offset that is selected according to the (left off / right switching / steering hold) to AS_IS relative steering angle Shitahr. For reference, data obtained by adding the Migisetsuji offset Csr to AS_IS relative steering angle θhr (θhr + Csr), data obtained by adding the Hokajiji offset Csk (θhr + Csk) and data obtained by adding the left Setsuji offset Csl (θhr + Csl), lower It is shown by a broken line in order from.
[0052]
　As shown in FIG. 13, since AS_IS relative steering angle θhr hardly changes in the holding steering state, TS_IS estimated steering angle θse also becomes substantially constant.
[0053]
　20 ° will be described fault diagnosis and backup of the rotor sensor 22 with TS_IS estimated steering angle θse calculated by the present embodiment.
[0054]
　Torque sensor in this embodiment has a double system, from 20 ° rotor sensor 22 is output TS_IS angle θs1 and? S2. It added TS_IS estimated steering angle θse these two data, the failure diagnosis and backup. That performs three in majority of TS_IS angle θs1 and θs2 and TS_IS estimated steering angle Shitase, when a two-to-one, it is diagnosed that the angle sensor corresponding to one fails. Then, the angle sensor corresponding to 1 if one system of 20 ° rotor sensor 22, using the other system as a backup. When performing the majority vote is not the same value, the difference may also be regarded as the same value as long as it is within a certain range.
[0055]
　Incidentally, if the torque sensor does not become a double line, it can not be backed up, it is possible fault diagnosis. That is, compared with the one TS_IS angle θs and TS_IS estimated steering angle θse output from 20 ° rotor sensor 22, (or if the difference is above a certain range) If there is no match, 20 ° rotor sensor 22 and / or it can be diagnosed that the Hall IC sensor 21 has failed.
[0056]
　In the above embodiment, although the correction offset calculation unit 80 from TS_IS relative steering angle θsr are subtracted AS_IS relative steering angle Shitahr, it may subtract the TS_IS relative steering angle θsr from AS_IS relative steering angle Shitahr . In this case, instead of adding a corrective offset to AS_IS the steering angle estimating portion 100 relative steering angle Shitahr, it will be subtracted. Further, Hokajiji offset Csk is calculated by correcting for the offset calculation unit 80 have been stored in the correction offset storage unit 90, left in the correction offset storage unit 90 Setsuji offset Csl and Migisetsuji offset Csr stores only, Hokajiji offset Csk may be calculated in the steering angle estimating portion 100. The method of the relative steering angle of a relative steering angle section 60 may be a method other than the above, if there is no angular period difference, relative steering angle of is unnecessary. The method of steering judgment by the steering judging portion 70 also may be a method other than the above, for example may be determined steering direction using the steering angle and the motor rotation angular velocity.
DESCRIPTION OF SYMBOLS
[0057]
1 handle (steering
wheel) 2 steering shaft (column shaft, the handle
shaft) 10 torque sensor
12 vehicle speed sensor
13 battery
20 motor
21 Hall IC sensor
22 20 ° rotor sensor
24 40 ° rotor sensor
30 control unit (ECU)
60 relative steering angle unit
70 steering determining unit
71 the hysteresis width setting unit
72 hysteresis central value calculating section
73 steering method determination unit
74 maintenance determination unit
80 corrects for the offset calculation unit
81 the steering speed calculator
82 steering acceleration calculating unit
83 gear characteristic learning unit
84 learning result holding unit
90 corrective offset storage section
100 a steering angle estimating portion

claims

A first angle sensor for detecting a first steering angle via the gear mechanism, an electric power steering apparatus characterized by at least a second angle sensor for detecting a second steering angle without passing through the gear mechanism,
　the gear mechanism a corrective offset calculation unit for calculating a corrective offset to learn characteristics,
　the electric power steering apparatus characterized by comprising a steering angle estimating section for estimating the second steering angle using a correction offset .
[Requested item 2]
　Comprising a relative steering angle section for relative steering angle of the first steering angle and the second steering angle,
　the correction offset calculation unit, a first steering angle and the second steering angle that is the relative steering angle of the electric power steering apparatus according to claim 1 for calculating the correction offset based.
[Requested item 3]
　Comprising a steering judging portion judges the steering direction,
　the correction offset calculation unit, an electric power steering apparatus according to claim 1 or 2 calculates the correction offset corresponding to the determined steering direction.
[Requested item 4]
　The second angle sensor has become a multi-system, if one system of the second angle sensor fails, to perform a backup of the second angle sensor using measured values ​​and the estimated value of the second steering angle the electric power steering apparatus according to any one of claims 1 to 3 that is a.
[Requested item 5]
　Based on the measured value and the estimated value of the second steering angle, the electric power steering device according to any one of claims 1 to 4 for monitoring and diagnosis of the second angle sensor.
[Requested item 6]
　The correction offset calculation unit,
　an electric power steering device according to any one of claims 1 to 5 for calculating a corrective offset to learn the deviation of the first steering angle and the second steering angle.
[Requested item 7]
　The correction offset calculation unit,
　wherein the extent of angular cycles of the first angle sensor learns a plurality of the deviation calculated at predetermined intervals, learned the corrective offset the average value of the plurality of deviations the electric power steering apparatus according to claim 6,.
[Requested item 8]
　The electric power steering apparatus according to any one of claims 1 to 7 wherein the first angle sensor and the second angle sensor is mounted on the input shaft side of the steering shaft.