JPH0813650B2 - Rudder angle midpoint detector - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a steering angle midpoint detection device for detecting the midpoint of the steering angle of a steering mechanism, and more particularly to an improvement aimed at improving the midpoint detection accuracy. .

[Prior art]

In a power steering apparatus that assists the steering force based on the detection result of the steering torque applied to the steering wheel, the steering angle is usually selected as one of the steering conditions.

Conventionally, as a means for detecting the steering angle, one using a sensor such as a potentiometer for detecting the movement of the steering wheel shaft or the rack shaft is known.

In such a steering angle detecting means, when the vehicle travels straight, the output of the sensor is adjusted and determined so as to have a predetermined output value, and the midpoint of the steering angle is detected thereby.

[Problems to be Solved by the Invention]

However, in the conventional rudder angle detecting means, the output value of the sensor corresponding to the midpoint of the rudder angle is determined in advance, so that it may change due to the secular change of the characteristic value of the steering mechanism such as the camber and the toe-in and the change due to the maintenance of the steering mechanism. However, there is a problem in that a predetermined output value of the sensor and a midpoint of a steering angle at which the vehicle goes straight ahead are deviated from each other, and the midpoint cannot be accurately detected.

Therefore, in order to eliminate the above deviation and detect the midpoint with high accuracy, it becomes necessary to correct the output value of the sensor at regular intervals or every time maintenance is performed.

The present invention has been made in view of such circumstances, and when the vehicle speed is higher than a predetermined value and the steering torque is smaller than a steering torque setting value that is preset according to the vehicle speed, the vehicle is traveling straight. Yes, that is, the steering angle is determined to be near the midpoint, the vehicle speed, steering torque, and the steering position of the steering mechanism are detected, and the midpoint of the steering angle is detected using these, and there is no need to correct the sensor output value. It is an object of the present invention to obtain a steering angle midpoint detection device with improved midpoint detection accuracy.

[Means for solving the problem]

A rudder angle midpoint detection device according to the present invention is a device for detecting the midpoint of the rudder angle of a steering mechanism that converts the rotation of a steering wheel of a vehicle into a lateral movement for steering, and detects the vehicle speed of the vehicle. Vehicle speed detecting means, means for comparing the vehicle speed detected by the vehicle speed detecting means with a predetermined value, a torque sensor for detecting a steering torque applied to the steered wheels, and a steering position for detecting a steering position of the steering mechanism. Detecting means, means for comparing a steering torque set value preset according to the vehicle speed and a steering torque detected by the torque sensor, and a vehicle speed detected by the vehicle speed detecting means is larger than the predetermined value, Moreover, when the steering torque is smaller than the steering torque set value, a means for reading the steering position of the steering mechanism detected by the steering position detecting means in time series, and the means for reading the means. Characterized in that it comprises a means for detecting the midpoint of the steering angle based on a plurality of steering position and the current steering position up to the previous I.

[Action]

In the present invention, the vehicle speed, the steering torque, and the steering position of the steering mechanism are detected, and when the detected vehicle speed is larger than a predetermined value and the detected steering torque is smaller than a steering torque set value preset according to the vehicle speed, the detection is performed. The steering position is read in time series, and the midpoint of the steering angle is detected based on the read plurality of steering positions up to the previous time and the current steering position.

〔Example〕

Hereinafter, the present invention will be described in detail with reference to the drawings showing an embodiment thereof. FIG. 1 is a partially cutaway front view of a power steering apparatus using a steering angle midpoint detecting device according to the present invention, and FIG. 2 is II-II of FIG.
FIG. 3 is an enlarged sectional view taken along line III-III in FIG. 1 showing the structure of a rotation detector which is steering position detecting means.

In the drawing, reference numeral 1 denotes a rack shaft, which is concentrically inserted in a cylindrical rack shaft case 2 which is fixed to a part of the vehicle body with the longitudinal direction as the left-right direction. Further, 3 is a pinion shaft, which is rotatably supported inside the pinion shaft case 4 continuously provided in the vicinity of one end of the rack shaft case 2 in a state in which its axis is oblique to the rack shaft 1.

As shown in FIG. 2, the pinion shaft 3 is composed of an upper shaft 3a and a lower shaft 3b which are coaxially connected to each other via a torsion bar 5, and the upper shaft 3a is installed in a pinion shaft case 4 by a ball bearing 40. It is supported and its upper end is interlocked with the steering wheel via a universal joint (not shown). The lower shaft 3b is
A position near the upper end of the pinion shaft case 4 is supported by a four-point contact ball bearing 41 in the pinion shaft case 4 in a state where a lower portion of the pinion shaft case 4 is appropriately projected. The four-point contact ball bearing 41 is externally fitted to the lower shaft 3b from the lower end side thereof, and a step portion formed near the upper end of the lower shaft 3b and externally fitted from the lower end side to be caulked and fixed to the outer peripheral surface. After being positioned on the outer side of the lower shaft 3b in the axial direction by being clamped on both sides of the inner ring by the formed collar 42, the lower shaft 3b is fitted into the pinion shaft case 4 through the lower opening, An annular shoulder portion formed in the lower portion of the case 4 and a lock nut 43 screwed into the case 4 through the opening are clamped on both sides of the outer ring so as to extend axially in the pinion shaft case 4 inside. It is positioned and applies a radial load acting on the lower shaft 3b and an axial load in both directions.

The middle part of the lower shaft 3b protruding from the pinion shaft case 4 has a pinion tooth 30 having an appropriate length in the axial direction.
When the pinion shaft case 4 is fixed to the upper side of the rack shaft case 2 by a fixing bolt 44, one end of the rack shaft 1 is formed inside the rack shaft case 2. A rack tooth 10 is formed at a position close to the portion and formed to have an appropriate length in the axial direction, and the lower shaft 3b and the rack shaft 1 are engaged with each other with their axes intersecting each other. The lower shaft 3b extends further downward than the engagement position with the rack shaft 1, and has a lower end portion coaxial with the lower shaft 3b, and a large bevel gear 31 is fitted with its tooth forming surface facing downward. The large bevel gear 31 is supported by a needle roller bearing 33 in a bevel gear housing 20 that is continuously provided below the rack shaft case 2 in a manner surrounding the large bevel gear 31. Therefore, the lower shaft 3b is made up of rack teeth by the four-point contact ball bearing 41 and the needle roller bearing 33.
It is supported at both ends of the meshing position between the 10 and the pinion teeth 30, and the amount of bending of the lower shaft 3b at the meshing position is kept within a predetermined allowable range.

Further, at the meshing position of the rack tooth 10 and the pinion tooth 30, there is provided a rack guide 12 for pressing the rack shaft 1 by the urging force of the push spring 11 toward the pinion shaft 3 so that they are meshed with each other without a gap. The rack shaft 1 is supported while being held by the rack guide 12 and the lower shaft 3b from both sides in the radial direction at the meshing position, and the rack shaft case on the opposite side of the continuous position with the pinion shaft case 4 is supported. It is supported by a bearing brush 13 fitted inside the end of the rack 2, and is movable in the axial direction of the rack shaft case 2. The left and right ends of the rack shaft 1 projecting from both sides of the rack shaft case 2 are respectively connected to left and right wheels (not shown) via separate ball joints 14, 14, respectively, and tie rods 15, 1
The wheels are steered to the left and right as the rack shaft 1 moves in the axial direction.

Reference numeral 6 in FIG. 2 denotes a torque sensor for detecting a steering torque applied to the steering wheel. The torque sensor is externally fitted to the upper shaft 3a and rotates together therewith, and the lower end face of the torque sensor is centered on the shaft center of the upper shaft 3a. A low antibody holding member 60 formed by forming a ring-shaped low antibody, and a detector that is fitted onto the lower shaft 3b and rotates together with the lower shaft 3b, and a detector slidingly contacting the upper end surface of the lower shaft 3b at one point in the radial direction on the resistor. The detector holding member 61 thus formed constitutes a potentiometer. The upper shaft 3a of the pinion shaft 3 rotates about its axis according to the rotation of the steering wheel, but the road resistance acting on the wheels acts on the lower shaft 3b via the rack shaft 1. The torsion bar 5 interposed therebetween is twisted according to the steering torque applied to the steering wheel. The torque sensor 6 includes an upper shaft 3a and a lower shaft as the torsion bar 5 is twisted.
The relative displacement in the circumferential direction with respect to 3b is output as a potential corresponding to the sliding contact position between the detector and the resistor, and when the torsion bar 5 is not twisted, in other words, steering wheel operation. The initial adjustment is made so as to output a predetermined reference potential when the above is not performed. Torque sensor 6
Is inputted to the control unit 7, which compares the signal with the reference potential to recognize the direction and the magnitude of the steering torque, and which is provided as described below for steering assist. A drive signal is issued to the motor 8 of.

The steering assisting motor 8 transmits its rotational force to the lower shaft 3b through an electromagnetic clutch 16, a planetary gear speed reducer 9 and a small bevel gear 32 that meshes with the large bevel gear 31 and has a smaller diameter than this. Is.

The electromagnetic clutch 16 has an annular shape and includes a coil portion 161 fixed to an intermediate case 81 of the motor 8 and a rotating shaft 80 of the motor 8.
A main driving part 162 which is fitted onto one side of the same coaxially and which rotates with the rotary shaft 80, and which is opposed to the main driving part 162 in the form of a disc and is driven by an electromagnetic force generated by energizing the coil part 161. Part 1
It is composed of an engagement / disengagement portion 163 that engages and disengages 62, and engages / disengages the rotational force of the motor 8.

The planetary gear speed reducer 9 is fitted in the engagement / disengagement portion 163, rotates, and has a sun gear. One end of the planetary gear reduction gear 9 is supported by a bearing fitted in the main drive portion, and the other end is fitted in a planet carrier 93 described later. A sun shaft 90 supported by a fixed bearing, a ring-shaped outer ring 91 fixed to a casing end surface 82 of the motor 8 coaxially with the rotating shaft 80, an inner peripheral surface of the outer ring 91 and the Sun axis
A plurality of planetary gears 92, 92 that rotate around the sun gear outer peripheral surface of each of the 90 sun gears, respectively, rotate about their respective axes and revolve around the axis of the sun gears, and these planetary gears 92, 92. Each of them is supported by a planet carrier 93 and has an outer diameter smaller than that of the motor 8. The motor 8 and the electromagnetic clutch 16 are integrated on one side of the rotary shaft 80. The output shaft 94 of the planetary gear reduction device 9 is fitted and fixed to the axial center position of the planet carrier 93 located coaxially with the rotation shaft 80 of the motor 8,
It is projected to an appropriate length outside the casing. The small bevel gear 32 is fitted to the tip of the output shaft 94 with its tooth forming surface facing the tip side, and the bevel gear 32 together with the output shaft 94 is connected to the planet gears 92, 92 ... It is designed to rotate according to the revolution of the.

The motor 8, the electromagnetic clutch 16, the planetary gear reduction device 9
Means that these shaft centers are substantially parallel to the shaft center of the rack shaft 1 and are fitted into the bevel gear housing 20 with the small bevel gear 32 inside and the small bevel gear inside the housing 20. 32 is a large bevel gear 31 fitted to the lower end of the lower shaft 3b.
And is fixed to a bracket 2a provided outside the rack shaft case 2. Backlash adjustment between the large bevel gear 31 and the small bevel gear 32 is performed by the planetary gear reduction device 9
Can be easily fitted into the bevel gear housing 20 by changing the thickness and / or the number of shims provided at the abutting portion between the casing of the planetary gear speed reducer 9 and the bevel gear housing 20.

A rotation detector 17 for detecting the rotation position of the motor 8 is provided on the other side of the rotation shaft 80 of the motor 8.
Is a disc-shaped member that is externally fitted to the other side of the rotation shaft 80 of the motor 8, and has a magnet plate 170 having two north and south poles and a predetermined mounting angle β (in this embodiment, β = 135 °) and two reed switches 171 and 171 mounted. FIG. 4 is a waveform diagram showing the output waveform of the rotation detector. Since the two reed switches 171, 171 are mounted with a mounting angle β of 135 °, the output waveforms are output 90 degrees out of phase. Since each of these outputs four waveforms in one rotation, the rotation detector 17 has a resolution of 1/16 of one rotation by detecting the rising and falling edges.

The rotation detector 17 can detect the rotation speed from 0 and can detect the relative position of the rotor, as compared with a conventional rotation detector such as a tachogenerator.

In addition, it is smaller than the photo interrupter type rotary encoder, is resistant to high temperatures, is less subject to aging, and is less expensive. Furthermore, since the output waveform is a pulse output, the detection result can be easily loaded into a CPU such as a microcomputer.

In addition to the output signal of the torque sensor 6 described above, the output signal of the rotation detector 17 and the output signal of the vehicle speed detector 18 for detecting the vehicle speed are input to the control unit 7, and the control described below is performed to the motor. 8 and a drive signal for driving the electromagnetic clutch 16 are output.

 Next, the control by the control unit 7 will be described.

FIG. 5 is a block diagram showing the configuration and control operation of the control unit.

The torque detection signal of the torque sensor 6 advances its phase and stabilizes the system by a phase compensation unit 71a, an angular acceleration detection unit 71b that detects the angular acceleration of the rotation of the steered wheels, and the steering mechanism of the present invention. Midpoint decision circuit for midpoint decision
71c, a lock detection unit 71f that detects the lock of the motor 8, an angular velocity detection unit 71g that detects the angular velocity ω of the steering wheel rotation, and a torque function generation unit 73g that generates a function according to the absolute value | T | of the steering torque T. Each has been entered.

Further, the vehicle speed detection signal of the vehicle speed detector 18 is the lock detection unit.
71f, a midpoint detection circuit 71c, a vehicle speed function generation unit 73f that generates a function according to the vehicle speed V, and the angular acceleration of the steering wheel output from the angular acceleration detection unit 71b are given, and according to the angular acceleration and the vehicle speed V, The steering angle θ output from the correction current function unit 73b that determines the correction current Ic that corrects the inertial force during acceleration / deceleration of the motor 8 and the inertial force around the vehicle legs and the steering angle θ output from the steering angle determination unit 71d described later are given. , A change current function unit that determines a change current Ia that changes the characteristic of the instruction current I according to the steering angle θ and the vehicle speed
It is input to 73c respectively.

Further, the rotation detection signal of the rotation detector 17 is the lock detection unit.
71f, the midpoint determination unit 71c, the angular acceleration detection unit 71b, the angular velocity detection unit 71g, and the rotation detection signal are input to the steering angle determination unit 71d that determines the steering angle θ from the midpoint position of the midpoint determination circuit 71c. .

The lock detection unit 71f detects the rotation of the motor 8 when the torque and the vehicle speed are higher than the respective predetermined values by the input rotation detection signal, vehicle speed detection signal and torque detection signal,
Accordingly, the presence or absence of lock is detected, and its output signal is given to the electromagnetic clutch 16 via the drive circuit 72b.

The output ω of the angular velocity detection unit 71g is given to the angular velocity function unit 73d which generates a function according to the angular velocity. The function portion 73d is supplied with the change current Ia, and the change current Ia is applied with an offset amount. The output signal of the phase compensation unit 71a and the change current Ia are given to the instruction current function unit 73a which generates the instruction current I to the motor 8. Further, the output signal of the vehicle speed function generating unit 73f is given to the torque function generating unit 73g,
The torque function fd corresponding to the vehicle speed is output. The output is given to the subtraction current function unit 73e, and the subtraction current Ir is generated by the output of the angular velocity function unit 73d and the output.

The output signal of the instruction current function unit 73a is input to the subtractor 74c, where the subtraction current I output from the subtraction current function unit 73e is output.
r is subtracted, and the subtraction result is given to the adder 74a.

The output signal of the correction current function unit 73b is added to the adder 74a, and the addition result is given to the subtractor 74b.

In the subtractor 74b, the feedback signal from the current detection circuit 71e that detects the current consumption of the motor 8 is subtracted from the addition result, and the subtraction result is PWM (Pulse-Width Mo
dulation: pulse width modulation) The motor 8 via the drive circuit 72a
Given to.

 Next, the operation will be described.

FIG. 6 is a flowchart showing the lock detection control. In step 10, it is determined whether or not the ignition switch (not shown) is turned on. If not, the vehicle speed V of the vehicle speed detector 18 is read in step 11.
Whether the vehicle speed V is greater than the vehicle speed threshold V _s1 is determined by step 1
When it is determined in step 2 and is large, the steering torque T from the torque sensor 6 is read in step 13 below. The steering torque T
Is determined to be greater than the torque threshold T _s1 in step 14, and when it is greater than that, the rotational position of the motor 8 from the rotation detector 17 is read in step 15, and the value indicates whether the motor 8 is rotating in step 18. It is determined whether the motor 8 is rotating. If it is not rotating, it returns. If the motor 8 is not rotating, it is determined that the motor 8 is locked.
Is turned off to disconnect the connection between the motor 8 and the planetary gear speed reducer 9 to free the steering mechanism from the motor 8. Then, in step 18, a lock alarm (not shown) is turned on and the process returns.

On the other hand, when it is determined in step 10 that the engine is rising, the electromagnetic clutch 16 is turned off in step 19, and the motor 8 is turned on in step 20. When the motor 8 is turned on, it is determined in step 21 that a predetermined time has elapsed, and then the rotational position of the motor 8 is read from the rotation detector 17 in step 22, and it is determined in step 23 whether or not the motor 8 is rotating by the value. If it is determined that the motor 8 is rotating, the motor 8 is turned off in step 24, and the electromagnetic clutch 16 is turned on in step 25. Step
When it is determined in 23 that the motor 8 is not rotating, the lock alarm is turned on in step 26 and the process returns.

Next, detection of angular acceleration and motor inertial control using the same will be described.

FIG. 7 is a flowchart showing calculation of angular acceleration and control of motor inertia using the calculation.

First, in step 30, the torque T from the torque sensor 6 is read, then in step 31, the angular acceleration detection unit 71b reads the rotation speed ω _m of the motor 8 from the rotation detector 17,
In step 32, the angular acceleration of the steering wheel is calculated by the following calculation.

Next, the influence of the inertial force of the motor 8 and the inertial force around the wheels around the wheel, which is determined in advance by the correction current function unit 73b, is corrected by the angular acceleration given to the steering wheel and the vehicle speed V obtained in step 33. Find the correction current Ic. Next, the correction current Ic obtained in step 34 is input to the adder 74a and added to the instruction current I obtained in the instruction current function unit 73a.
As a result, when the angular acceleration at the start and end of the steering assist by the motor 8 is detected, the correction current Ic corresponding to the inertial force and the inertial force around the foot is added to the instruction current I. The ring is improved.

Next, the calculation of the midpoint of the steering angle and the steering wheel return control using the calculation will be described, which is the gist of the present invention.

FIG. 8 is a steering wheel return control, FIG. 9 is a calculation of the midpoint of the steering angle, and FIG. 10 is a flow chart showing the procedure for determining the left and right positions of the steering angle. FIG. 11 is a graph showing the characteristic of the relationship between the motor current and the torque in the command current function unit 73a, in which the ordinate indicates the command current I and the abscissa indicates the torque T. Further, the broken line shows the characteristic when the vehicle speed is high, and the alternate long and short dash line shows the characteristic when the vehicle speed is low.

In FIG. 8, first, the torque T is read in step 40, and it is judged in step 41 whether the torque T is within the dead zone. If the torque T is in the dead zone, step 42 is executed.
Then, it is determined whether or not the midpoint calculation routine described later is completed. When the midpoint calculation is completed, the rotational position of the motor 8 is read from the rotation detector 17 in step 43, and in step 44, the steering angle determination unit 71d determines the steering angle θ based on the rotational position and the midpoint. To decide. When the steering angle θ is determined, the changing current Ia is changed in step 45 by the steering angle θ and the vehicle speed V.
Then, the indicated current function unit 73a calculates the value and direction of the indicated current I.

On the other hand, if it is determined in step 41 that the position is not the dead zone, the process returns. If the intermediate calculation is not completed in step 42, the rotational position of the motor 8 is read from the rotation detector 17 in step 46, and left and right described later in step 47. The change current Ia is calculated by the minimum steering angle value determined in the determination routine, and the value and direction of the instruction current I is calculated.

In the midpoint calculation routine shown in FIG. 9, the vehicle speed V is read in step 50, it is determined in step 51 whether the vehicle speed V is higher than the threshold value V _{s2, and} if it is higher, in step 52 the torque setting value according to the vehicle speed is set. After setting T _s2 , the torque T is read in step 53, and it is determined in step 54 whether the torque T is smaller than the torque set value T _s2 . When it is small, it is determined that the vehicle is traveling straight, and when it is small, the number of times when it is small is counted, and in step 56, the rotational position of the motor 8 at that time is read. Then, in step 57, the rotational position is added to the total of the rotational positions up to the previous time, the addition result is divided by the number of counts to obtain the steering angle midpoint, and the value of the steering angle midpoint is updated. If the vehicle speed V is smaller than the threshold value V _s2 or the torque T is larger than the torque set value T _{s2 in} step 51, the _routine returns.

However, since this midpoint calculation requires a large amount of calculation time, the return control is performed by the left / right determination routine described below until the calculation is completed.

In the left / right determination routine shown in FIG. 10, the vehicle speed V is read in step 60, and it is determined in step 61 whether the vehicle speed V is larger than the threshold value V _{s3. If} it is larger, the torque T is read in step 62, and the torque T is read in step 63. Is integrated to determine whether the direction of the integrated value is to the right. When it is right, the right value of the minimum steering angle is updated in step 65, and when it is left, the left value of the minimum steering angle is updated in step 64 and the process returns.

On the other hand, when the change current Ia is obtained from the steering angle θ in the return control as shown in FIG. 11, the instruction current I in the return control of the steered wheels when the torque is within the dead zone according to the change current Ia and the vehicle speed V is obtained.
Change. For example, when the vehicle speed V is high, as shown by the broken line, when the torque T enters the dead zone, the rate of increase of the instruction current I is increased, and the motor 8 is controlled so as to speed up the return to the middle point. When it is small, when the torque T enters the dead zone as shown by the chain line, the rate of increase of the instruction current I is reduced and the motor 8 is controlled so as to delay the return to the middle point.

Next, the angular velocity control of the steering wheel will be described. FIG. 12 is a flowchart showing the angular velocity control of the steering wheel. First, in step 70, the rotational position of the motor 8 is read by the output of the rotation detector 17. Next, in step 71, the steering angle is obtained from the rotational position, and an offset amount is given to the angular velocity function part 73d based on the change current Ia corresponding to the steering angle. Next, in step 72, the vehicle speed V is read, and in step 73, the torque T is read. Next step
At 74, the vehicle speed function generator 73f calculates the vehicle speed function fv from the vehicle speed V, and the torque function generator 73g determines the speed control amount fd from the vehicle speed function fv. Next, in step 75, the angular velocity ω
Is detected, and the angular velocity function fω taking into account the offset amount is obtained. Next, the subtraction current Ir is obtained by the subtraction current function unit 73e from the angular velocity function fω and the velocity control amount fd obtained in step 76, and this is input to the subtractor 74c, whereby the current corresponding to the torque T and the angular velocity ω is obtained. Subtract from the indicated current I.

In the present embodiment, the case where the device of the present invention is used for the return control of the steered wheels of the electric power steering device has been described, but the present invention is not limited to this and can be used for other controls. Needless to say.

Further, in the present embodiment, the rotation detector for detecting the rotation position of the motor is used as the steering position detecting means, but the present invention is not limited to this, and the steering mechanism such as the displacement of the rack shaft, the turning position of the steering wheel shaft, etc. If the relative position of can be detected,
Any means may be used.

〔The invention's effect〕

As described above, according to the present invention, the steering torque and the vehicle speed are detected, and the steering position of the steering mechanism is detected and detected when the steering torque is smaller than the steering torque set value preset according to the vehicle speed. Since the midpoint of the steering mechanism is detected by the steering position, the midpoint can be detected by the relative steering position, correction of the midpoint of the steering position detection means is unnecessary, and the accuracy of midpoint detection is improved. Produce the effect.

[Brief description of drawings]

1 is a partially cutaway front view showing an embodiment of a power steering apparatus according to the present invention, FIG. 2 is an enlarged sectional view taken along the line II-II of FIG. 1, and FIG. 3 is a structure of a rotation detector. III-I in FIG.
Fig. 4 is an enlarged sectional view taken along line II, Fig. 4 is a waveform diagram showing the output waveform of the rotation detector, Fig. 5 is a block diagram showing the configuration and operation of the control unit, and Figs. 6 to 10 explain each control operation. 11 is a graph showing the characteristic of the relationship between the motor current and torque in the command current function section, and FIG. 12 is a flowchart of angular velocity control. 6 ... Torque sensor, 8 ... Motor, 17 ... Rotation detector, 18 ... Vehicle speed detector, 71c ... Midpoint detection unit, 71d ... Steering angle determination unit

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Claims (1)

[Claims] 1. An apparatus for detecting a midpoint of a steering angle of a steering mechanism for converting a turning wheel of a vehicle into a lateral movement for steering, a vehicle speed detecting means for detecting a vehicle speed of the vehicle, Means for comparing a vehicle speed detected by the vehicle speed detecting means with a predetermined value; a torque sensor for detecting a steering torque applied to the steered wheels; a steering position detecting means for detecting a steering position of the steering mechanism; Means for comparing a steering torque set value preset according to the steering torque detected by the torque sensor, the vehicle speed detected by the vehicle speed detecting means is higher than the predetermined value, and the steering torque is When it is smaller than the steering torque set value, a means for reading the steering position of the steering mechanism detected by the steering position detecting means in time series, and a means for reading the steering position until the last time. And a means for detecting the midpoint of the steering angle based on the plurality of steering positions and the current steering position.