JP5181817B2 - Steering angle detection device for vehicle and electric power steering device using the same - Google Patents

Description

  The present invention provides a relative rudder angle detecting means for detecting a relative rudder angle of a steering mechanism for turning a steered wheel of a vehicle, and an absolute rudder angle of the steering mechanism based on the relative rudder angle detected by the relative rudder angle detecting means. The present invention relates to a steering angle detection device for a vehicle including an absolute steering angle calculation means for calculating the steering angle, and an electric power steering device using the same.

Conventionally, in a vehicle such as a passenger car or a truck, a steering assisting force is applied to a steering mechanism by driving an electric motor according to a steering torque by which the driver steers the steering wheel as a steering device, thereby reducing the steering force of the driver. Electric power steering devices are widespread.
In this type of electric power steering device, many control functions using the steering angle of the steering wheel have been developed in order to ensure the steering stability and comfort of the vehicle, and based on the steering angle quickly after the vehicle starts. In order to perform the control function, it is required to detect the steering angle as soon as possible.

  In order to accurately detect the absolute rotational position of the steering wheel, conventionally, the steering wheel, the first resolver for detecting the first steering angle that is the rotational angle of the steering shaft coupled to the steering wheel, A second resolver having a counter electrode number different from that of one resolver and detecting a second steering angle which is a rotation angle of the steering shaft; a motor for assisting steering by a steering mechanism coupled to the steering shaft via a reduction gear; A third resolver that detects a motor electrical angle that is a rotation angle of the motor, and an absolute rotation angle position of a steering wheel is obtained from the first steering angle, the second steering angle, and the motor electrical angle. An electric power steering apparatus has been proposed (see, for example, Patent Document 1).

Also, the absolute steering angle of the steering wheel is detected based on its own neutral position, and when the ignition switch is turned off, the absolute steering angle at that moment is stored in the memory, and is stored when the ignition switch is turned on next time. There has been proposed a steering angle detection device that detects an absolute steering angle based on the obtained value (see, for example, Patent Document 2).
Japanese Patent No. 3875202 (first page, FIG. 2) Japanese Patent No. 2946964 (first page, FIG. 2)

However, since the conventional example described in Patent Document 1 requires at least three resolvers, there is an unsolved problem that the configuration is complicated and the cost is increased.
Further, in the conventional example described in Patent Document 2, the absolute steering angle at the moment when the ignition switch is turned off is stored in the memory, and then stored when the ignition switch is turned on next time. Since the value is used as an absolute steering angle for control of the electric power steering device, for example, when the steering wheel is steered while the ignition switch is OFF, it is based on the wrong absolute steering angle. Therefore, there is an unsolved problem that accurate control cannot be performed.

  Accordingly, the present invention has been made paying attention to the unsolved problems of the above-described conventional example, and a steering angle detection device for a vehicle capable of determining the effectiveness of an absolute steering angle immediately before the system stops and this An object of the present invention is to provide an electric power steering apparatus using the above.

  In order to achieve the above object, a steering angle detection device for a vehicle according to claim 1 includes a relative steering angle detection means for detecting a relative steering angle of a steering mechanism that steers a steered wheel of the vehicle, and the relative steering angle detection. A steering angle detection device for a vehicle, comprising absolute steering angle calculation means for calculating an absolute steering angle of the steering mechanism based on a relative steering angle detected by the means, wherein the absolute steering angle calculation means immediately before the system stops Absolute steering angle storage means for storing the calculated absolute steering angle in a nonvolatile memory, an absolute steering angle provisional value based on the absolute steering angle storage value stored in the nonvolatile memory and the relative steering angle at the time of system startup Temporary value calculating means, self-aligning torque calculating means for calculating a self-aligning torque reference value based on the absolute steering angle provisional value and the characteristics of the vehicle model, and the actual self-aligning torque of the vehicle An actual self-aligning torque detection means to detect, and when the difference between the self-aligning torque reference value and the actual self-aligning torque is equal to or less than a predetermined value, the absolute steering angle provisional value is determined to be valid; At least an effectiveness determining means for determining that the absolute steering angle provisional value is invalid when a difference between the self-aligning torque reference value and the actual self-aligning torque exceeds a predetermined value; It is a feature.

According to a second aspect of the present invention, there is provided a vehicular rudder angle detecting device comprising: a relative rudder angle detecting unit that detects a relative rudder angle of a steering mechanism that steers a steered wheel of a vehicle; A steering angle detection device for a vehicle, comprising absolute steering angle calculation means for calculating an absolute steering angle of the steering mechanism based on an angle,
Absolute steering angle storage means for storing in the nonvolatile memory the absolute steering angle calculated by the absolute steering angle calculation means immediately before the system is stopped, the absolute steering angle storage value stored in the nonvolatile memory at the time of system startup, and the relative steering Absolute steering angle provisional value calculation means for calculating an absolute steering angle provisional value based on the angle, self-aligning torque detection means for detecting the actual self-aligning torque of the vehicle, and the inverse of the actual self-aligning torque and the vehicle Absolute steering angle estimation means for multiplying model characteristics to calculate an absolute steering angle estimation value, and when the difference between the absolute steering angle provisional value and the absolute steering angle estimation value is a predetermined value or less, the absolute steering angle Effectiveness to determine that the provisional value is valid, and to determine that the provisional value of the absolute steering angle is invalid when the difference between the provisional value of the absolute steering angle and the estimated value of the absolute steering angle exceeds a predetermined value At least with the judging means It is characterized in that it comprises.

  Further, the vehicle steering angle detection device according to claim 3 is the invention according to claim 1 or 2, wherein the absolute steering angle calculation means includes a neutral point detection means for detecting a neutral point of the steering angle, and after the system is started. When the steering angle neutral point is detected by the neutral point detection means, and the absolute steering angle calculation value can be used based on the detected steering angle neutral point and the relative steering angle detected by the relative steering angle detection means And a steering angle selecting means for selecting the absolute steering angle calculation value as the absolute steering angle in place of the absolute steering angle provisional value.

Furthermore, the vehicle steering angle detection device according to claim 4 is the invention according to claim 3, wherein the steering angle selection means selects the absolute steering angle calculation value instead of the absolute steering angle provisional value. The gradual change means for gradually changing the absolute steering angle provisional value to the absolute steering angle calculation value is provided.
Still further, the steering angle detection device for a vehicle according to claim 5 is the invention according to any one of claims 1 to 4, wherein the absolute steering angle storage means is provided between a system start time and a system stop time. When the absolute steering angle calculation value cannot be calculated, the absolute steering angle provisional value is stored in the nonvolatile memory as the absolute steering angle immediately before the system stops.

  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 fifth aspects, and is based on an absolute steering angle detected by the vehicle steering angle detection device. Steering assist control is performed.

  According to the present invention, the absolute rudder angle immediately before the system is stopped is stored in the nonvolatile memory, the absolute rudder angle stored in the nonvolatile memory at the time of starting the system is set as the absolute rudder angle initial value, and the absolute rudder angle initial value is set. The absolute steering angle provisional value is calculated from the relative steering angle, and the effectiveness of this absolute steering angle provisional value is determined based on the self-aligning torque, so the system can be started without using multiple sensors. There is an effect that the absolute steering angle can be calculated more accurately.

  In addition, by performing the steering assist control using the vehicle steering angle detection device that can obtain the above-described effect, there is an effect that it is possible to provide an electric power steering device that can further ensure steering stability. .

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
FIG. 1 is an overall configuration diagram showing an embodiment of the present invention. In the figure, reference numeral 1 denotes a steering device. The steering device 1 includes a steering shaft 3 on which a steering wheel 2 is mounted, and the steering shaft 3. A rack and pinion mechanism 4 connected to the opposite side of the steering wheel 2 and left and right steered wheels 6 connected to the rack and pinion mechanism 4 via a connecting mechanism 5 such as a tie rod.

An electric motor 8 is connected to the steering shaft 3 via a speed reduction mechanism 7 constituted by, for example, a worm gear.
The electric motor 8 operates as a steering assist force generation motor that generates a steering assist force of the electric power steering apparatus. The electric motor 8 is supplied with a battery voltage Vb output from a battery 11 mounted on the vehicle via an ignition switch 12 and is driven and controlled by a controller 14 that is directly supplied to a built-in motor drive circuit. .

  The control device 14 includes a motor current detection value Imd detected by a motor current sensor 15 that detects a motor drive current supplied to the electric motor 8, and a steering detected by a steering torque sensor 16 disposed on the steering shaft 3. The steering torque T input to the wheel 2 is input, the vehicle speed Vs detected by the vehicle speed sensor 17 as a vehicle speed detection unit is input, and further detected by the motor rotation angle sensor 18 that detects the rotation angle of the electric motor 8. The motor rotation angle θm is input.

  Further, the control device 14 has a self-holding function that continues to hold the power supply for a predetermined time even after the ignition switch 12 is turned off, and stops the absolute steering angle φa calculated by the absolute steering angle calculation unit described later. A non-volatile memory 19 composed of, for example, an EEPROM, which is stored as an absolute steering angle storage value φam at the time when the ignition switch 12 is turned off, is connected.

Here, the steering torque sensor 16 detects the steering torque applied to the steering wheel 2 and transmitted to the steering shaft 3. For example, the torsion bar in which the steering torque is interposed between an input shaft and an output shaft (not shown). The torsional angular displacement is converted into an electrical signal, and the torsional angular displacement is detected with a magnetic signal and converted into an electrical signal.
The control device 14 is constituted by, for example, a microcomputer, and the configuration is shown in FIG. 2 in a functional block diagram. That is, the controller 14 detects the motor current detection value Imd detected by the motor current sensor 15, the steering torque T detected by the steering torque sensor 16, the vehicle speed Vs detected by the vehicle speed sensor 17, and the motor rotation detected by the motor rotation angle sensor 18. The angle θm is input, and the absolute steering angle stored value φam immediately before the end of the previous steering assist control stored in the nonvolatile memory 19 can be read.

  Then, the control device 14 receives the steering torque T, the vehicle speed Vs, the motor rotation angle θm, and the absolute steering angle memory value φam, and calculates the absolute steering angle φa based on these, and the steering angle detection device 20 for steering, A current command value calculation unit 21 that calculates a steering assist current command value Iref for the electric motor 8 based on the torque T and the vehicle speed Vs, and the steering assist current command value Iref calculated by the current command value calculation unit 21 and motor current detection A current feedback control unit 22 that calculates a voltage command value Vref by performing a current feedback process based on the detected motor current value Imd detected by the unit 15, and a voltage command value Vref calculated by the current feedback control unit 22 A motor drive circuit 23 that is input and drives and controls the electric motor 8 is provided.

  The control device 14 also differentiates the absolute steering angle φa calculated by the vehicle steering angle detection device 20 to calculate the absolute steering angular velocity ωa, and the absolute steering angle calculated by the vehicle steering angle detection device 20. Steering that performs so-called steering return control for returning the steering wheel 2 to the neutral position when the steering force to the steering wheel 2 is loosened in a steered state based on the absolute steering angular velocity ωa and the vehicle speed Vs calculated by the differential circuit 24. The return control unit 25 and an adder that adds the steering return control signal HR calculated by the steering return control unit 25 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 26.

  As shown in FIG. 3, the vehicle steering angle detection device 20 receives the motor rotation angle θm detected by the motor rotation angle sensor 18 and calculates the relative steering angle φr of the steering wheel 2 based on the motor rotation angle θm. A calculating unit 31, a rudder angular speed calculating unit 32 that calculates the rudder angular speed ωr by differentiating the relative rudder angle φr calculated by the relative rudder angle calculating unit 31, a steering torque T, a vehicle speed Vs, a relative rudder angle φr, and a rudder angular speed. A neutral point estimation unit 33 for estimating the neutral point rudder angle φn of the steering wheel 2 at the time of straight traveling when ωr is input, and the neutral point rudder angle φn estimated by the neutral point estimation unit 33 is subtracted from the relative rudder angle φr. And an absolute rudder angle calculation unit 34 for calculating an absolute rudder angle calculation value φao.

  Here, as shown in FIG. 4, the neutral point estimation unit 33 receives the steering torque T, the steering angular speed ωr, and the vehicle speed Vs, and determines whether or not the vehicle is in the straight traveling state based on these. When the determination result of the straight traveling state determination unit 33a is a straight traveling state, the unit 33a and a neutral point rudder angle calculation unit 33b that calculates a neutral point rudder angle φn based on the relative rudder angle φr and the vehicle speed Vs. Has been. The straight traveling state determination unit 33a has a steering torque T equal to or lower than a preset threshold Tth that has a high possibility of straight traveling, and a steering angular speed ωr equal to or smaller than a predetermined threshold ωth that has a high possibility of straight traveling. When the vehicle speed Vs is equal to or higher than the vehicle speed threshold Vsth where the possibility of straight travel is high, the straight travel signal St having a logical value “1” representing the straight travel state is sent to the neutral point steering angle calculator 33b. And a neutral point confirmation flag Fn for the steering angle switching unit 40 described later until the system is first driven straight after the power is turned on to the control device 14 via the ignition switch 12. It is reset to “0” and the neutral point determination flag Fn is set to “1” when the vehicle goes straight ahead for the first time.

The neutral point rudder angle calculation unit 33b performs the calculation of the following equation (1) when the straight traveling signal St having the logical value “1” is input from the straight traveling state determination unit 33a, thereby calculating the current neutral point rudder angle φn ( k) is calculated.
φn (k) = {φr−φn (k−1)} · D + φn (k−1) (1)

Here, φr is the relative steering angle, φn (k−1) is the previous neutral point steering angle, and D is a reliability coefficient determined by the vehicle speed Vs. The reliability coefficient D is calculated with reference to the reliability coefficient calculation map shown in FIG. 5 based on the vehicle speed Vs. As shown in FIG. 5, the reliability coefficient calculation map is represented by a characteristic diagram with the vehicle speed Vs on the horizontal axis and the reliability coefficient D on the vertical axis. When the vehicle speed Vs is less than the set vehicle speed Vss1, = 0, D = 1 when the vehicle speed Vs is greater than or equal to the set vehicle speed Vss1 and less than the set vehicle speed Vss2, D = 2 when the vehicle speed Vs is greater than or equal to the set vehicle speed Vss2 and less than the set vehicle speed Vss3, and the vehicle speed Vs is greater than or equal to the set vehicle speed Vss3 When D is less than the set vehicle speed Vss4, D = 3, D = 4 when the vehicle speed Vs is equal to or higher than the set vehicle speed Vss4 and lower than the set vehicle speed Vss5, and D = 5 when the vehicle speed Vs is equal to or higher than the set vehicle speed Vss5. Has been. Note that the reliability coefficient calculation map is not limited to the above configuration, and may be linear characteristics or non-linear characteristics.

  Further, the vehicle steering angle detection device 20 is relative to the absolute steering angle storage value φam read from the nonvolatile memory 19 when the system is started, that is, when the ignition switch 12 is turned on and the control device 14 is turned on. The provisional value calculation unit 35 that calculates the absolute steering angle provisional value φap by adding the steering angle φr, and the absolute rudder preset when the absolute steering angle provisional value φap calculated by the provisional value calculation unit 35 is invalid. And an absolute steering angle alternative value output unit 36 that outputs the angle alternative value φaa.

  Furthermore, the vehicle steering angle detection device 20 includes an actual self-aligning torque detector 37 that detects an actual self-aligning torque SATr of the vehicle, and an actual self-aligning torque SATr detected by the actual self-aligning torque detector 37. And the vehicle speed Vs, an effectiveness determination unit 38 that determines whether the absolute steering angle provisional value φap is valid or invalid, and the absolute steering angle provisional value φap based on the determination result of the validity determination unit 38 And an absolute steering angle selector 39 that selects one of the absolute steering angle alternative values φaa.

  Here, the actual self-aligning torque detector 37 differentiates the steering torque T input from the steering torque sensor 16 and the motor rotation angle θm detected by the motor rotation angle sensor 18 to calculate the motor rotation angular velocity ωm. A motor rotation angular velocity ωm input from the rotation angular velocity calculation unit 19a, a motor rotation angular acceleration αm input from the motor rotation angular acceleration calculation unit 19b that calculates the motor rotation angular acceleration αm by differentiating the motor rotation angular velocity ωm, The current command value Iref output from the current command value calculation unit 21 is input, and based on these, the following equation (2) is calculated and input to the steering mechanism from the road surface via the steered wheels 6. The actual self-aligning torque SATr is calculated.

  SATr (s) = Tm (s) + T (s) − J ・ αm (s) − Fr ・ sign (ωm (s)) ………… (2)

Here, Tm (s) is the assist torque generated by the electric motor 8, T (s) is the steering torque, J is the inertia of the electric motor 8, Fr is the static friction of the electric motor 8, and s is the 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.

  Moreover, the effectiveness determination part 38 multiplies the vehicle model Gv (s) calculated based on the vehicle speed Vs by the absolute steering angle provisional value φap, as shown in the formula (3) described later, thereby self-aligning. The torque reference value SATm is calculated, and the state where the absolute value | SATr−SATm | of the difference between the input actual self-aligning torque SATr and the calculated self-aligning torque reference value SATm is equal to or less than the set threshold value ΔSATth is continued for a predetermined time. When the absolute steering angle provisional value φap is determined to be valid, the selection flag Fs for the absolute steering angle selection unit 39 is set to “1” for selecting the absolute steering angle provisional value φap, and | SATr−SATm | A selection flag for the absolute steering angle selector 39 when it is determined that the absolute steering angle provisional value φap is invalid when a state exceeding the set threshold ΔSATth is continued for a predetermined time. s to select the absolute steering angle alternative value φaa is reset to "0".

Therefore, the validity determination unit 38 executes the validity determination process shown in FIG. The validity determination process is started when the power is supplied to the control device 14, and as shown in FIG. 7, first, initialization is performed in step S11, and count values Cnt1 and Cnt2 described later are set to “0”. And the selection flag Fs is reset to “0”.
Next, the process proceeds to step S12, where the vehicle speed Vs, the actual self-aligning torque SATr, and the absolute steering angle provisional value φap are read, and then the process proceeds to step S12a when the vehicle is stopped and the steering wheel 2 is not steered. If the above condition is satisfied, the process returns to step S12. If the condition is not satisfied, the process proceeds to step S13.

In step S13, the self-aligning torque reference value SATm is calculated by calculating the following equation (3).
SATm = Gv (s) * φap (3)

Here, Gv (s) is a vehicle model for calculating self-aligning torque in the steering mechanism of the vehicle, has a characteristic set based on the vehicle speed Vs, and uses a transfer function of the vehicle characteristic. It may be calculated or obtained by simulation using a vehicle motion model after measuring a characteristic value for each vehicle by experiment. In this case, the vehicle speed Vs is taken on the horizontal axis and the vehicle model Gv (s) is taken on the vertical axis. The vehicle model calculation map is preferably calculated with reference to the vehicle speed Vs.

Next, the fact that the actual self-aligning torque SATr can be calculated from the absolute steering angle using the vehicle model Gv (s) will be described.
The equation of motion of the vehicle is expressed by the following equation (4).

Where m is the vehicle mass, I is the vehicle moment of inertia, l _f is the distance between the vehicle center of gravity and the front axle, I _r is the distance between the vehicle center of gravity and the rear axle, K _f is the cornering power of the front tire, and K _r Is the cornering power of the rear tire, V is the vehicle speed, N is the overall steering ratio, δ _f is the actual steering angle (δ _f = φ / N), β is the side slip angle of the vehicle center of gravity, and γ is the yaw rate.

On the other hand, the relationship between the actual steering angle δ _f and the self-aligning torque SAT can be expressed by the following equation (5) including the side slip angle β and the yaw rate γ.

However, the coefficients c ₁₁ = −2εK _f , c ₁₂ = −2εK _f l _f / V, and d ₁₁ = 2εK _f , where ε is a trail.
Then, the above-described equation (3) can be calculated by solving the above-described equations (4) and (5) as simultaneous equations and replacing the actual steering angle δ _f with the absolute steering angle provisional value φap.

  Next, the process proceeds to step S14, where it is determined whether or not the absolute value | SATm−SATr | of the value obtained by subtracting the actual self-aligning torque SATr from the self-aligning torque reference value SATm is equal to or smaller than the set threshold value ΔSATth. When −SATr | ≦ ΔSATth, the process proceeds to step S15 to set a value obtained by incrementing “1” to the current first count value Cnt1 for counting the number of continuations of validity as a new count value Cnt1. After the second count value Cnt2 is cleared to “0”, the process proceeds to step S16.

In this step S16, it is determined whether or not the first count value Cnt1 exceeds a preset set value Cs1, and when Cnt1 ≦ Cs1, the process returns to step S12.
When the determination result in step S16 is Cnt1> Cs1, the process proceeds to step S18, the selection flag Fs is set to “1” and output to the absolute steering angle selection unit 39, and then the process ends.

If the determination result in step S14 is | SATm−SATr |> ΔSATs, the process proceeds to step S19, and a value obtained by adding “1” to the current second count value Cnt is set as a new second count. The value is set to Cnt2 (= Cnt2 + 1) and the first count value Cnt1 is cleared to “0”, and then the process proceeds to step S20.
In this step S20, it is determined whether or not the second count value Cnt2 exceeds a preset set value Cs2, and if Cnt2 ≦ Cs2, the process returns to step S12.

If the determination result in step S20 is Cnt2> Cs2, the process proceeds to step S22, the selection flag Fs is reset to “0”, and the process ends.
In the process of FIG. 7, the process of step S13 corresponds to the self-aligning torque calculating means.

  When the selection flag Fs input from the effectiveness determination unit 38 is set to “1”, the absolute rudder angle selection unit 39 sets the absolute rudder angle provisional value φap calculated by the absolute rudder angle provisional value calculation unit 35. This is output to the steering angle switching unit 40 as the absolute steering angle provisional selection value φas, and when the selection flag Fs is reset to “0”, the absolute steering output from the absolute steering angle alternative value output unit 36 The angle alternative value φaa is selected and output to the steering angle switching unit 40 as the absolute steering angle provisional selection value φas.

  Furthermore, the vehicle rudder angle detection device 20 uses the absolute rudder angle calculation value φao and the absolute rudder angle selection unit 39 based on the neutral point determination flag Fn set by the neutral point estimation unit 33 described above. The steering angle switching unit 40 that selects one of the angle selection values φas and outputs it as the absolute steering angle φa, and the absolute steering angle output from the steering angle switching unit 40 immediately before the system stops, that is, immediately before the ignition switch 12 is turned off. An absolute steering angle storage unit 41 for storing φa in the nonvolatile memory 19 as an absolute steering angle storage value φam is provided.

  The rudder angle switching unit 40 determines the absolute rudder angle provisional selection value φas input from the absolute rudder angle selection unit 39 when the neutral point determination flag Fn input from the neutral point estimation unit 33 is reset to “0”. Is output to the differentiation circuit 24 and the steering return control unit 25 as an absolute steering angle φa. When the neutral point determination flag Fn is set to “1”, the absolute steering angle calculation value φao input from the absolute steering angle calculation unit 34 is selected, and this is set as the absolute steering angle φa to the differentiation circuit 24 and the steering. Output to the return control unit 25. At this time, when the neutral point determination flag Fn is reversed from “0” to “1”, it is determined whether or not the absolute steering angle alternative value φaa has been selected as the absolute steering angle provisional selection value φas so far. When the steering angle alternative value φaa is selected, the absolute steering angle calculation value φao is immediately switched. When the absolute steering angle provisional value φap is selected, the difference between the absolute steering angle provisional value φap and the absolute steering angle calculation value φao When | φap−φao | is less than the set value Δφs, it immediately switches to the absolute steering angle calculation value φao, and the difference | φap−φao | between the absolute steering angle provisional value φap and the absolute steering angle calculation value φao is equal to or larger than the set value Δφs. In some cases, the absolute steering angle provisional value φap is gradually changed to the absolute steering angle calculation value φao.

  Therefore, the rudder angle switching unit 40 performs the rudder angle switching process shown in FIG. In this steering angle switching process, first, in step S31, it is determined whether or not the neutral point determination flag Fn input from the neutral point estimation unit 33 is set to “1”, and the neutral point determination flag Fn is set to “0”. When it is reset to "", the routine proceeds to step S32, where the absolute steering angle provisional selection value φas input from the absolute steering angle selector 39 is output as the absolute steering angle φa, and the neutral point determination flag Fn is set to “1”. When it is set, the process proceeds to step S33.

In this step S33, it is determined whether or not the previous absolute steering angle provisional selection value φas is the absolute steering angle substitution value φaa, and when it is the absolute steering angle substitution value φaa, the process proceeds to step S34 and the absolute steering angle calculation unit is performed. After the absolute steering angle calculation value φao calculated at 34 is output as the absolute steering angle φa, the processing is terminated.
When the determination result in step S33 is that the previous absolute steering angle provisional selection value φas is the absolute steering angle provisional value φap, the process proceeds to step S36.

In this step S36, it is determined whether or not the difference | φap−φao | between the current absolute steering angle provisional value φap and the absolute steering angle calculation value φao is equal to or larger than the set value Δφs, and | φap−φao | <Δφs. If there is, the process proceeds to step S34, and if | φap−φao | ≧ Δφs, the process proceeds to step S37.
In this step S37, it is determined whether or not the current absolute steering angle provisional value φap is larger than the absolute steering angle calculation value φao, and when φap> φao, the process proceeds to step S38, and the current absolute steering angle provisional value φap. A value obtained by subtracting the predetermined value Δφs1 from the current absolute steering angle provisional value φap (= φap−Δφs1) is calculated, and then the process proceeds to step S39, where the calculated absolute steering angle provisional value φap is the absolute steering angle calculation value φao. It is determined whether or not the following is true. If φap> φao, the process proceeds to step S40, the absolute steering angle provisional value φap is output as the absolute steering angle φa, and then the process returns to step S31.

Further, when the determination result in step S39 is φap ≦ φao, the process proceeds to step S34.
Further, when the determination result in step S37 is φap <φao, the process proceeds to step S42, and the value obtained by adding the predetermined value Δφs1 to the current absolute steering angle provisional value φap is set to the current absolute steering angle provisional value φap ( = Φap + Δφs1), and then the process proceeds to step S43 to determine whether or not the calculated absolute steering angle provisional value φap is greater than or equal to the absolute steering angle calculation value φao, and if φap <φao, the process proceeds to step S40. Then, the absolute steering angle provisional value φap is output as the absolute steering angle φa. When the determination result in step S43 is φap ≧ φao, the process proceeds to step S34.

  Furthermore, the vehicle steering angle detection device 20 executes an absolute steering angle calculation process shown in FIG. In this absolute steering angle calculation process, first, at step S1, it is determined whether or not the neutral point determination flag Fn is set to “1”. When the point object flag Fn is reset to “0”, the process proceeds to step S2, where it is determined whether or not the ignition switch 12 is in the initial state inverted from the off state to the on state. Sometimes, the process proceeds to step S3, and the absolute steering angle stored value φam is read from the nonvolatile memory 19.

  Next, the process proceeds to step S4, the relative steering angle φr is read, and then the process proceeds to step S5, where the absolute steering angle provisional value φap is calculated by adding the relative steering angle φr to the absolute steering angle stored value φam, and then step The process proceeds to S6, where it is determined whether or not the selection flag Fs is set to “1”. When the selection flag Fs is set to “1”, the process proceeds to Step S7 and the absolute steering angle provisional value φap. Is output as the absolute steering angle selection value φas, and when the selection flag Fs is reset to “0”, the process proceeds to step S8, and the preset absolute steering angle alternative value φaa is output as the absolute steering angle selection value φas. To do.

The absolute rudder angle storage unit 41 updates and stores the absolute rudder angle φa output from the rudder angle switching unit 40 when the ignition switch 12 is turned off in a predetermined storage area of the nonvolatile memory 19.
Further, as shown in FIG. 9, the steering return control unit 25 inputs a steering wheel return basic current circuit 50 that outputs a steering wheel return basic current value Ir with a predetermined function based on the absolute steering angle φa, and a vehicle speed Vs and inputs a predetermined value. A gain circuit 51 that outputs a gain Kv corresponding to the vehicle speed Vs by a function; a multiplier 52 that multiplies the steering return basic current value Ir from the steering return basic current circuit 50 and the gain Kv from the gain circuit 51; 52, the switch 53 for outputting the output Ir · Kv to the contact point a or b, the zero output circuit 54 for setting the output when the switch 53 is switched to the contact point b side to 0, the absolute steering angle φa and the absolute value A steering angular velocity ωa is input, and a code determination circuit 55 that determines the coincidence or non-coincidence of the signs of both is configured.

  The sign determination circuit 55 outputs a switch signal SW as a determination signal to switch the contact of the switch 53. When the signs of the absolute steering angle φa and the steering angular speed ωa match, the sign determination circuit 55 switches to the contact b with the switch signal SW. 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 velocity ωa becomes zero. Then, the output Ir · Kv from the multiplier 52 selected by the switch 53 or the “0” output from the zero output circuit 54 is supplied to the adder 26 as the steering return current HR.

Next, the operation of the above embodiment will be described.
Now, it is assumed that the vehicle is stopped and the ignition switch 12 is off. In this state, since the battery voltage Vb from the battery 11 is not supplied to the microcomputer constituting the control device 14, the microcomputer constituting the control device 14 is in a stopped state, and the electric motor 8 is stopped to the steering shaft 3. The steering assist force is not transmitted.

  When the ignition switch 12 is turned on from this vehicle stop state, the battery voltage Vb is supplied to the microcomputer of the control device 14 so that the microcomputer of the control device 14 is activated, and the motor current shown in FIG. Steering assist control processing by the sensor 15, the absolute steering angle calculation unit 20, the current command value calculation unit 21, the current feedback control unit 22, the motor drive circuit 23, the steering return control unit 25, and the adder 26, the absolute steering angle shown in FIG. The calculation process, the effectiveness determination process shown in FIG. 7, and the steering angle switching process shown in FIG. 8 are started.

  For this reason, in the vehicle steering angle detection device 20, when the ignition switch 12 is turned on, the straight traveling state determination unit 33a of the neutral point estimation unit 33 determines whether or not the vehicle is in the straight traveling state. Since the vehicle is in a stopped state, at least the vehicle speed Vs is less than the vehicle speed threshold value Vsth, so that the neutral point determination flag Fn is maintained to be reset to “0”, and the straight traveling signal St becomes a logical value “0”. The neutral point rudder angle calculator 33b does not calculate the neutral point rudder angle φn.

Further, in the current command value calculation unit 21, assuming that the steering wheel 2 is not steered, the steering torque T detected by the steering torque sensor 16 is substantially “0”, and the vehicle speed Vs detected by the vehicle speed sensor 17 is also Since it is substantially “0”, the calculated steering assist current command value Iref is also “0”.
On the other hand, in the steering return control unit 25, since the absolute steering angular speed ωa is “0”, the contact point of the switch 53 is switched to the b side and the steering return current HR “0” output from the zero output circuit 54 is added. 26.

  For this reason, the addition output of the adder 26 becomes “0”, which is supplied to the current feedback control unit 22. At this time, the electric motor 8 is in a stopped state, so that the motor drive current Imd detected by the motor current sensor 15 is also Since it becomes “0”, the voltage command value Vref output from the current feedback control unit 22 also becomes “0”, the motor drive current Im output from the motor drive circuit 23 also becomes “0”, and the electric motor 8 Continue the stopped state.

  In this state, since the absolute steering angle provisional value calculation process shown in FIG. 6 is executed, the neutral point determination flag Fn is reset to “0”. Therefore, the process proceeds from step S1 to step S2, and the ignition switch 12 Is an initial state that has just changed from the off state to the on state, so that the process proceeds from step S2 to step S3, and the absolute steering angle stored value φam immediately before the previous system stop stored in the nonvolatile memory 19 is read. .

Next, the process proceeds to step S4, where the relative steering angle φr calculated by the relative steering angle calculation unit 31 is read, and then the process proceeds to step S5, where the absolute steering is performed by adding the relative steering angle φr to the absolute steering angle stored value φam. The provisional value φap is calculated.
At this time, the rudder angle switching unit 40 executes the rudder angle switching process of FIG. 8, and the neutral point determination flag Fn output from the neutral point estimation unit 33 is reset to “0” as described above. Therefore, the process proceeds from step S31 to step S32, and the absolute steering angle provisional value φap selected by the steering angle selection unit 39 is output to the differentiation circuit 24 and the steering return control unit 25 as the absolute steering angle φa.

  At this time, since the vehicle is stopped and the steering wheel 2 is not being steered, the process returns from step S12a to step S12 in the effectiveness determination process of FIG. At this time, since the selection flag Fs is reset to “0” in the initialization process, the absolute steering angle alternative value φa output from the absolute steering angle alternative output unit 36 is selected by the absolute steering angle selection unit 39. This is output to the differentiation circuit 24 and the steering return control unit 25 as an absolute steering angle φa.

Even in this state, since the steering wheel 2 is not steered and the electric motor 8 is stopped, the relative absolute rudder angle φr does not change, and the absolute rudder angle provisional value φap does not change. “0” is maintained, and the steering return current HR output from the steering return control unit 25 also maintains “0”.
When the steering wheel 2 is stationary in this state, the steering torque T corresponding to the steering force applied to the steering wheel 2 is detected by the steering torque sensor 16 accordingly. Therefore, the steering current command value Iref corresponding to the steering torque T is calculated by the current command value calculation unit 21 and supplied to the current feedback control unit 22 via the adder 26. Therefore, the current feedback control unit 22 Thus, the voltage command value Vref corresponding to the deviation ΔI between the steering assist current command value Iref and the motor current detection value Imd detected by the motor current sensor 15 is calculated. By supplying this voltage command value Vref to the motor drive circuit 23, a motor drive current Im is output from the motor drive circuit 23, the electric motor 8 is driven to rotate, and a steering assist torque corresponding to the steering torque T is obtained. Is generated. The steering assist torque generated by the electric motor 8 is transmitted to the steering shaft 3 via the speed reduction mechanism, and the steering wheel 2 can be steered with a light steering force.

In this way, when the electric motor 8 is driven to rotate and the steering assist torque is generated, the actual self-aligning torque SATr calculated by the actual self-aligning torque detector 37 is the value of the steering assist current command value Iref, The value is increased or decreased from “0” according to the value of the steering torque T, the value of the motor rotation angular acceleration αm, and the value of the motor rotation angular velocity ωm.
At this time, the vehicle remains stopped, but the steering wheel 2 is steered. Therefore, in the validity determination process, as shown in FIG. 7, the process proceeds from step S12a to step S13 to change the vehicle model Gv (s). Use to calculate the self-aligning torque reference value SATm. Since the self-aligning torque reference value SATm is calculated using the stationary vehicle model Gv (s) ′ when the vehicle is stopped, an accurate self-aligning torque reference value SATm is calculated. The difference between the value SATm and the actual self-aligning torque SATr becomes small, the absolute steering angle provisional value φap is determined to be valid, and the selection flag Fs is set to “1”. Therefore, the absolute steering angle provisional value φap is selected by the absolute steering angle selection unit 39 and the absolute steering angle provisional value φap selected by the steering angle switching unit 40 is used as the absolute steering angle φa in the differentiation circuit 24 and the steering return control unit 25. Is output.

  Thereafter, the vehicle starts traveling, and the vehicle speed Vs becomes equal to or higher than the vehicle speed threshold value Vth. However, when the vehicle is in a turning traveling state in which the steering wheel 2 is steered, the steering torque T becomes larger than the threshold value Tth. The straight traveling state determination unit 33a of the neutral point estimating unit 33 does not determine the straight traveling state, and the straight traveling signal St maintains the logical value “0” and the neutral point determination flag Fn is reset to “0”. maintain.

  However, when the vehicle starts traveling, the self-aligning torque reference value SATm calculated in step S13 in the effectiveness determination process shown in FIG. 7 changes according to the vehicle speed Vs at that time, and the actual self The difference from the actual self-aligning torque SATr calculated by the aligning torque detector 37 is smaller than the set value ΔSATs. Therefore, the process proceeds from step S14 to step S15, the first count value Cnt1 is incremented, and when this state continues and the first count value Cnt1 exceeds the set value Cs1, the absolute steering angle provisional value φap is The effective state is determined, the process proceeds from step S16 to step S18, and the state where the determination flag Fs is set to “1” is maintained.

Therefore, the absolute steering angle provisional value φap calculated by the absolute steering angle provisional value calculation unit 35 is selected by the absolute steering angle selection unit 39 and supplied to the steering angle switching unit 40. Since the steering angle switching unit 40 continues the state in which the neutral point determination flag Fn is reset to “0”, the absolute steering angle provisional value φap is output to the differentiation circuit 24 and the steering return control unit 25 as the absolute steering angle φa. To do.
Therefore, the steering return control unit 25 calculates a steering return current HR corresponding to the absolute steering angle φa and the absolute steering angular speed ωa. This steering return current HR compensates for the lack of steering assist torque when the steering wheel 2 returns to the neutral point by calculating a large steering return current HR because the vehicle speed sensitive gain Kv is large when the vehicle speed Vs is low. Can do.

  Thereafter, when the steering wheel 2 is returned to the vicinity of the neutral point and the vehicle is in the straight traveling state, the steering torque T is equal to or less than the threshold value Tth and the relative steering angular speed ωr is equal to or smaller than the threshold value ωth in the straight traveling state determination unit 33a of the neutral point estimating unit 33. When the vehicle speed Vs satisfies the condition equal to or higher than the vehicle speed threshold Vsth, the straight traveling signal St is set to the logical value “1”, and the neutral point determination flag Fn is set to “1”. Accordingly, the neutral point rudder angle calculation unit 33b calculates the neutral point rudder angle φn based on the vehicle speed Vs and the relative rudder angle φr, and this neutral point rudder angle φn is supplied to the absolute rudder angle calculation unit 34 to obtain the relative rudder angle φr. Is subtracted from the absolute steering angle calculation value φao.

  For this reason, in the rudder angle switching unit 40, in the rudder angle switching process of FIG. 8, the process proceeds from step S31 to step S33, and since the previous neutral point determination flag Fn was “0”, the process proceeds from step S33 to step S35. Transition. At this time, since the absolute steering angle provisional value φap is selected by the absolute steering angle selection unit 39, the process proceeds to step S36 through step S35, and the current absolute steering angle provisional value φap and the absolute steering angle calculation unit 34 calculate. When the deviation from the calculated absolute steering angle φao is less than or equal to the set value Δφs, the difference between the two is small, and even when the absolute steering angle provisional value φap is switched to the absolute steering angle calculated value φao, the absolute steering angle φa changes little and the steering is returned. The absolute steering angle φa is directly switched from the absolute steering angle provisional value φap to the absolute steering angle calculation value φao based on the determination that the influence on the steering return current HR calculated by the control unit 25 is small.

  However, when the deviation between the absolute steering angle provisional value φap and the absolute steering angle calculation value φao exceeds the set value Δφs, the routine proceeds from step S36 to step S37, where the absolute steering angle provisional value φap is the absolute steering angle calculation value. When larger than φao, by repeatedly subtracting the predetermined value Δφs1 from the absolute steering angle provisional value φap, the absolute steering angle becomes smaller than the absolute steering angle calculation value φao while gradually decreasing the absolute steering angle provisional value φap. The provisional value φap is switched to the absolute steering angle calculation value φao. Conversely, when the absolute steering angle provisional value φap is smaller than the absolute steering angle calculation value φao, the absolute steering angle provisional value φap is gradually increased by repeating the addition of the predetermined value Δφs1 to the absolute steering angle provisional value φap. When the absolute rudder angle calculation value φao or more is reached, the absolute rudder angle provisional value φap is switched to the absolute rudder angle calculation value φao.

Thus, when the difference between the absolute steering angle provisional value φap and the absolute steering angle calculation value φao is large, the absolute steering angle provisional value φap is gradually changed until it matches the absolute steering angle calculation value φao. A sudden change in φa can surely prevent the driver from feeling uncomfortable by affecting the steering return control.
It should be noted that the selection flag Fs indicates that the determination result in the effectiveness determination unit 38 is that the deviation between the actual self-aligning torque SATr and the self-aligning torque reference value SATm is large and the absolute steering angle provisional value φap is invalid. When reset to “0”, the absolute steering angle alternative value φaa is selected by the absolute steering angle selection unit 39 and is set as the absolute steering angle φa. In this state, the neutral point probability flag Fn is “1”. When it is set to "", it cannot be said that the absolute steering angle alternative value φaa corresponds to the actual absolute steering angle, so the process proceeds from step S35 to step S34 in the effectiveness determination process of FIG. Switch to absolute steering angle calculation value φao.

After that, when the ignition switch 12 is turned off, the self-holding circuit provided in the control device 14 self-holds the power-on state for a predetermined time, and during this time, the absolute steering angle output from the steering angle switching unit 40 φa is stored in the predetermined storage area of the nonvolatile memory 19 as an absolute steering angle storage value φam.
Thus, according to the first embodiment, the absolute rudder angle provisional value φap is obtained by adding the absolute rudder angle stored value φam and the relative rudder angle φr stored in the nonvolatile memory 19 when the system is started up. In addition to the calculation, the travelability determination unit 38 calculates the difference between the actual self-aligning torque SATr and the self-aligning torque reference value SATm. When the difference between the two is small, it is determined that the absolute steering angle provisional value φap is valid. Then, the absolute steering angle provisional value φap is set as the absolute steering angle φa. However, when the difference between the actual self-aligning torque SATr and the self-aligning torque reference value SATm is large, it is determined that the absolute steering angle provisional value φap is invalid, and the preset absolute steering angle alternative value φaa is used as the absolute steering angle. Set as φa. For this reason, only when the absolute steering angle provisional value φap is valid, the absolute steering angle provisional value φap is used as the absolute steering angle φa, so that the error rate of the absolute steering angle φa is reduced and good steering assist control is performed. Function can be demonstrated.

Next, a second embodiment of the present invention will be described with reference to FIG.
In the second embodiment, instead of determining the effectiveness of the absolute steering angle provisional value φap based on the difference between the actual self-aligning torque SATr and the self-aligning torque reference value SATm, the actual self-aligning torque The absolute rudder angle estimated value φax is calculated based on the SATr, and the effectiveness of the absolute rudder angle provisional value φap is determined based on the deviation between the absolute rudder angle estimated value φax and the absolute rudder angle provisional value φap. is there.

  In other words, the second embodiment has the same configuration as that of the first embodiment described above except that the validity determination unit 39 executes the validity determination process shown in FIG. Portions corresponding to those in the first embodiment are denoted by the same reference numerals, and detailed description thereof is omitted.

In the validity determination process of FIG. 10, the vehicle inverse model Gv ⁻¹ (s) in which the process of step S13 in the validity determination process of FIG. 7 in the first embodiment described above is an inverse model of the vehicle model Gv (s). Is multiplied by the actual self-aligning torque SATr to replace the step S51 for calculating the absolute steering angle estimated value φax, and the processing of step S14 is a value obtained by subtracting the absolute steering angle provisional value φap from the absolute steering angle estimated value φax. It is determined whether or not the absolute value | φax−φap | is equal to or smaller than a predetermined value Δφs. If | φax−φap | ≦ Δφs, it is determined that the absolute steering angle provisional value φap is valid, and the process proceeds to step S15. , | Φax−φap |> Δφs, it is determined that the absolute steering angle provisional value φap is invalid, and is replaced with step S52 which proceeds to step S19. It performs the same processing are denoted by the same step numbers to the corresponding step of Fig. 7, and detailed description thereof will be omitted this. Here, even if the vehicle inverse model Gv ^-1 (s) is calculated based on the transfer function of the vehicle characteristics, the relationship of the vehicle inverse model Gv ^-1 (s) to the vehicle speed Vs obtained by experiment is mapped. Thus, the vehicle inverse model Gv ⁻¹ (s) may be calculated based on the vehicle speed Vs.

According to the second embodiment, the absolute steering angle estimated value φax is calculated based on the actual self-aligning torque SATr using the vehicle inverse model Gv ⁻¹ (s), and the calculated absolute steering angle estimated value φax and When the deviation from the absolute steering angle provisional value φap is equal to or less than the predetermined value Δφs, it is determined that the absolute steering angle provisional value φap is valid, the selection flag Fs is set to “1”, and the absolute steering angle selection unit 39 The absolute steering angle provisional value φap is selected, but when the deviation between the calculated absolute steering angle estimated value φax and the absolute steering angle provisional value φap exceeds a predetermined value Δφs, it is determined that the absolute steering angle provisional value φap is invalid. Then, the selection flag Fs is reset to “0”, and the absolute steering angle selection unit 39 selects the absolute steering angle alternative value φaa.

For this reason, the effectiveness of the absolute steering angle provisional value φap can be accurately determined based on the absolute steering angle estimated value φax calculated based on the actual self-aligning torque SATr and the absolute steering angle provisional value φap. The same effect as the first embodiment can be obtained.
In the first and second embodiments, the actual self-aligning torque detector 37 calculates the formula (2) based on the steering torque T, the assist torque Tm, the motor rotation angular acceleration αm, and the motor rotation angular velocity ωm. Although the case where the actual self-aligning torque SATr is calculated by performing the calculation has been described, the present invention is not limited to this, and any actual self-aligning torque estimation method can be applied. The actual self-aligning torque is detected directly using a sensor such as a six-component force meter composed of a strain gauge, a magnetostrictive torque sensor, a pressure sensor, or the like attached to the steered wheels. It may be.

Moreover, in the said 1st and 2nd embodiment, although the case where the steering angle detection apparatus 20 for vehicles was applied to the electric power steering apparatus was demonstrated, it is not limited to this, The absolute mounted in a vehicle The vehicle steering angle detection device 20 can be applied to a control unit such as a suspension control unit or a travel control unit that requires a steering angle.
Further, in the first and second embodiments, the case where the actual self-aligning torque calculation unit 37 is provided in the vehicle steering angle detection device 20 has been described. An actual self-aligning torque calculation unit may be provided outside the control device 14 and the actual self-aligning torque SATr may be input to the control device 14 from the actual self-aligning torque calculation unit.

1 is an overall configuration diagram showing a first embodiment of the present invention. It is a block diagram which shows the functional block of a control apparatus. It is a block diagram which shows the specific structure of the steering angle detection apparatus for vehicles. It is a block diagram which shows the specific structure of a neutral point estimation part. It is a characteristic diagram which shows a reliability calculation map. It is a flowchart which shows an example of an absolute steering angle control processing procedure. It is a flowchart which shows an example of an effectiveness determination processing procedure. It is a flowchart which shows an example of a steering angle switching process procedure. It is a block diagram which shows the specific structure of a steering return control part. It is a flowchart which shows an example of the effectiveness determination processing procedure which shows the 2nd Embodiment of this invention.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Steering device, 2 ... Steering wheel, 3 ... Steering shaft, 7 ... Deceleration mechanism, 8 ... Electric motor, 14 ... Control device, 15 ... Motor current sensor, 16 ... Steering torque sensor, 17 ... Vehicle speed sensor, 18 ... Motor Rotation angle sensor, 19 ... Non-volatile memory, 20 ... Steering angle detection device for vehicle, 21 ... Current command value calculation unit, 22 ... Current feedback control unit, 23 ... Motor drive circuit, 24 ... Differentiation circuit, 25 ... Steering return control , 26 ... Adder, 31 ... Relative rudder angle calculator, 32 ... Relative rudder angle speed calculator, 33 ... Neutral point estimator, 34 ... Absolute rudder angle calculator, 35 ... Absolute rudder angle provisional value calculator, 36 ... Absolute steering angle alternative value output unit, 37 ... Actual self-aligning torque detection unit, 38 ... Effectiveness determination unit, 39 ... Absolute steering angle selection unit, 40 ... Steering angle switching unit

Claims (6)

Relative rudder angle detecting means for detecting the relative rudder angle of the steering mechanism for turning the steered wheels of the vehicle, and absolute for calculating the absolute rudder angle of the steering mechanism based on the relative rudder angle detected by the relative rudder angle detecting means A steering angle detection device for a vehicle provided with a steering angle calculation means,
Absolute steering angle storage means for storing in the nonvolatile memory the absolute steering angle calculated by the absolute steering angle calculation means immediately before the system is stopped, the absolute steering angle storage value stored in the nonvolatile memory at the time of system startup, and the relative steering Absolute steering angle provisional value calculation means for calculating an absolute steering angle provisional value based on the angle, self-aligning based on the absolute steering angle storage value stored in the non-volatile memory at the time of system startup and the characteristics of the vehicle model A self-aligning torque calculating means for calculating a torque reference value; an actual self-aligning torque detecting means for detecting an actual self-aligning torque of the vehicle; and the self-aligning torque reference value and the actual self-aligning torque. When the difference is less than or equal to a predetermined value, it is determined that the absolute steering angle provisional value is valid, and the self-aligning torque reference value and the actual value are The absolute steering angle provisional vehicle steering angle detecting device, wherein a comprises at least a validity judging means for judging to be invalid when the difference between the Ruff aligning torque exceeds a predetermined value. Relative rudder angle detecting means for detecting the relative rudder angle of the steering mechanism for turning the steered wheels of the vehicle, and absolute for calculating the absolute rudder angle of the steering mechanism based on the relative rudder angle detected by the relative rudder angle detecting means A steering angle detection device for a vehicle provided with a steering angle calculation means,
Absolute steering angle storage means for storing in the nonvolatile memory the absolute steering angle calculated by the absolute steering angle calculation means immediately before the system is stopped, the absolute steering angle storage value stored in the nonvolatile memory at the time of system startup, and the relative steering Absolute steering angle provisional value calculation means for calculating an absolute steering angle provisional value based on the angle, self-aligning torque detection means for detecting the actual self-aligning torque of the vehicle, and the inverse of the actual self-aligning torque and the vehicle Absolute steering angle estimation means for multiplying model characteristics to calculate an absolute steering angle estimation value, and when the difference between the absolute steering angle provisional value and the absolute steering angle estimation value is a predetermined value or less, the absolute steering angle Effectiveness to determine that the provisional value is valid, and to determine that the provisional value of the absolute steering angle is invalid when the difference between the provisional value of the absolute steering angle and the estimated value of the absolute steering angle exceeds a predetermined value At least with the judging means With vehicle steering angle detecting apparatus characterized by being.   The absolute rudder angle calculating means includes a neutral point detecting means for detecting a neutral point of the steering angle, a steering angle neutral point detected by the neutral point detecting means after system startup, and the detected rudder angle neutral point and the relative rudder. When the absolute steering angle calculation value becomes usable based on the relative steering angle detected by the angle detection means, the absolute steering angle calculation value is selected as the absolute steering angle instead of the absolute steering angle provisional value. The vehicle steering angle detection device according to claim 1, further comprising a steering angle selection unit.   The steering angle selection means gradually changes from the absolute steering angle provisional value to the absolute steering angle calculation value when the absolute steering angle calculation value is selected instead of the absolute steering angle provisional value. The vehicle steering angle detection device according to claim 3, wherein   The absolute rudder angle storage means is non-volatile as the absolute rudder angle provisional value as the absolute rudder angle immediately before the system stop when the absolute rudder angle calculated value cannot be calculated between the system start and the system stop. The vehicle steering angle detection device according to any one of claims 1 to 4, wherein the vehicle steering angle detection device is configured to be stored in a memory.   An electric power comprising the vehicle steering angle detection device according to any one of claims 1 to 5 and performing steering assist control based on an absolute steering angle detected by the vehicle steering angle detection device. Steering device.

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