JP3137847B2 - Electric power steering device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electric power steering apparatus in which the power of an electric motor is applied to a steering system as a steering assist force to reduce the steering force.

[0002]

2. Description of the Related Art In a conventional electric power steering apparatus, the applicant of the present invention disclosed in Japanese Patent Application Laid-Open No. 62-238165.
As disclosed in Japanese Patent Application Laid-Open Publication No. H10-260, a steering torque detecting means for detecting a steering torque of a steering system, a steering rotational speed detecting means for detecting a steering rotational speed of the steering system, and a return state detecting means for detecting a return state of the steering system A vehicle speed detecting means for detecting a speed of the vehicle, and a maximum value of an output signal of the steering rotational speed detecting means when the return state detecting means detects the return state, the vehicle speed is increased based on the output signal of the vehicle speed detecting means. Correction means for limiting to a value that decreases with
2. Description of the Related Art There is known a configuration in which a control signal of an electric motor that generates a steering assist force is determined based on an output signal of a steering torque detection unit and an output signal of a correction unit.

In the conventional electric power steering apparatus configured as described above, the maximum value (D _NMAX) of the return speed control signal (D _NMAX ) of the electric motor is set so as to decrease as the vehicle speed V increases in accordance with the vehicle speed V. ) And a motor speed control signal (D _N ) corresponding to the steering rotation speed N are stored in a memory as a table value in advance, and when the return state detecting means detects the return state of the steering system, comparing the control signal maximum value (D _NMAX) and the rotation speed control signal (D _N), exceeds the rotational speed control signal (D _N) returns the rotational speed control signal maximum value _{(D NMAX) (D N>} D NMAX ) Also returns the rotation speed control signal (D _N ) and the maximum value of the rotation speed control signal (D _NMAX )
When the vehicle is running at low speed, the return speed of the steering system is kept relatively high to improve the return performance, and when the vehicle is running at high speed, the return speed of the steering system is reduced to improve the return stability. Have improved.

As described above, the conventional electric power steering apparatus can maintain a large return speed of the electric motor when the vehicle is running at a low speed, so that the return performance can be improved and the vehicle can be driven at a high speed. In this case, the return speed of the electric motor is reduced in accordance with an increase in the vehicle speed, and the convergence time to the neutral position of the steering system can be shortened, so that the return stability can be improved.

[0005]

The conventional electric power steering apparatus improves the steering characteristics of the vehicle by using the induced voltage of the electric motor to vary the damping characteristic of the steering system. When driving at higher speeds, the vehicle behavior becomes more sensitive than at low speeds,
For example, when traveling on seams or steps of roads,
The steering wheel may be removed due to the road surface and tires. In addition, if the steering is performed near the resonance frequency of the yaw rate of the vehicle, the yaw rate gain of the vehicle increases, the vehicle behavior becomes more sensitive, and the feeling of response during steering may be insufficient. Therefore, it is required that the steering system be positively provided with damping characteristics, and it is necessary to provide the steering system with even greater damping characteristics.

Although the damping characteristics of the steering system can be improved by connecting a mechanical damping device to the steering system, the damping characteristics of a mechanical damping device such as a steering damper are determined by the viscosity of oil. If the setting is made to ensure stability during high-speed running of the vehicle, the self-aligning torque such as low-μ road running and low-speed running may be low, or the return performance of the steering system may be reduced in low-temperature conditions. is there. In addition, if such a mechanical damping device is newly provided in the steering system, there is a problem that the entire steering system becomes large, which leads to an increase in vehicle mountability and cost.

SUMMARY OF THE INVENTION The present invention has been made to solve such a problem, and an object thereof is to correct the damping characteristic of the steering system so as to increase as the vehicle speed increases, and to reduce the return characteristic of the steering system during low-speed running. It is an object of the present invention to provide an electric power steering device that can significantly improve the stability of vehicle behavior during high-speed running and that does not make the entire steering system large.

[0008]

In order to solve the above problems, an electric power steering apparatus according to the present invention includes a steering torque detecting means for detecting a steering torque of a steering system, and a steering for detecting a steering rotation speed of the steering system. A rotational speed detecting means, a steering state detecting means for detecting a going state and a returning state of the steering system, and a steering rotation based on a value corresponding to an output signal of the steering torque detecting means when the steering state detecting means detects the going state. The value corresponding to the output signal of the speed detecting means is subtracted and corrected, and when the return state is detected, the value corresponding to the output signal of the steering rotational speed detecting means is added and corrected to the value corresponding to the output signal of the steering torque detecting means. Motor control signal determining means for driving, and motor driving means for driving the motor based on the output signal of the motor control signal determining means. For example, forward the state of the steering system is Misao
When the steering torque direction and the steering rotation direction match.
The return state is a state that does not match .

Further, the electric power steering apparatus according to the present invention includes a steering torque detecting means for detecting a steering torque of a steering system, a vehicle speed detecting means for detecting a vehicle speed, and a forward state and a return state of the steering system. When the steering state detecting means detects the going state, a value corresponding to the output signal from the vehicle speed detecting means is subtracted from the value corresponding to the output signal from the steering torque detecting means, and the steering state is corrected. A motor control signal determining means for adding and correcting a value corresponding to the output signal from the vehicle speed detecting means to a value corresponding to the output signal of the steering torque detecting means when the detecting means detects the going state;
And a motor driving means for driving the electric motor based on the output signal of the motor control signal determining means, the steering system
The direction of the steering torque and the direction of the steering rotation match
And the return state does not match .

The electric power steering apparatus according to the present invention includes a steering torque detecting means for detecting a steering torque of a steering system, a steering rotational speed detecting means for detecting a steering rotational speed of the steering system, and a vehicle speed. A vehicle speed detecting means, a steering state detecting means for detecting a going state and a returning state of the steering system, and a steering rotational speed based on a value corresponding to an output signal of the steering torque detecting means when the steering state detecting means detects the going state. A value obtained by multiplying a value corresponding to the output signal of the detection means by a value corresponding to the output signal of the vehicle speed detection means is subtracted and corrected, and when a return state is detected, the steering is adjusted to a value corresponding to the output signal of the steering torque detection means. An electric motor system for adding and correcting a value obtained by multiplying a value corresponding to the output signal of the rotation speed detecting means by a value corresponding to the output signal of the vehicle speed detecting means. Includes a signal determining unit, an electric motor driving means for driving the electric motor based on the output signal of the motor control signal determining means, forward state of the steering system is a steering torque
The direction of steering and the direction of steering rotation match,
The states are not matched .

Further, the motor control signal determining means includes a correction for inhibiting the subtraction correction and the addition correction when the output signal of the steering rotational speed detecting means is smaller than a predetermined value which decreases as the output signal of the vehicle speed detecting means increases. Prohibition means is provided.

Further, instead of the steering rotation speed detecting means, a motor state detecting means for detecting an armature voltage and an armature current of the motor, and a steering rotation for calculating a steering rotation speed based on an output signal of the motor state detecting means. Speed calculation means is provided.

[0013]

[Action] electric power steering apparatus according to claim 1 is provided with a steering state detecting means and the motor control signal determining means, corresponding to the forward state and return the state of the steering system, corresponding to the output signals of the steering torque detecting means And the value corresponding to the output signal of the steering rotational speed detecting means are subtracted and added to determine the rotational speed control signal of the electric motor. It is possible to obtain the steering assist force or the braking force of the electric motor.

According to a second aspect of the present invention, there is provided an electric power steering apparatus comprising a steering state detecting means and a motor control signal deciding means. And the value corresponding to the output signal from the vehicle speed detecting means are subjected to subtraction correction and addition correction to determine the rotation speed control signal of the electric motor, so that the steering system goes to the forward state or the return state. It is possible to obtain a corresponding steering assist force or braking force of the electric motor.

Further, an electric power steering apparatus according to a third aspect of the present invention includes a steering state detecting means and an electric motor control signal determining means, and corresponds to an outgoing state and a returning state of the steering system, and outputs an output signal of the steering torque detecting means, respectively. And a value obtained by multiplying a value corresponding to the output signal of the steering rotation speed detecting means by a value corresponding to the output signal of the vehicle speed detecting means, by subtraction correction and addition correction to obtain a rotation speed control signal of the electric motor. Since it is configured to be determined, it is possible to obtain a steering assist force or a braking force of the electric motor according to the going state or the returning state of the steering system.

Further, in the electric power steering apparatus according to the fourth aspect , since the motor control signal determining means is provided with the correction inhibiting means, the output signal of the steering rotational speed detecting means is increased as the output signal of the vehicle speed detecting means increases. When the value is smaller than the predetermined value, the subtraction correction and the addition correction can be prohibited.

Further, in the electric power steering apparatus according to the first and third aspects, instead of the steering rotational speed detecting means, an electric motor state detecting means and a steering rotational speed calculating means are provided, and the motor voltage of the electric motor and the electric motor are provided. Since the current can be detected and the steering rotational speed can be calculated based on these voltages and currents, the steering assist force or the braking force of the electric motor can be obtained based on the calculated steering rotational speed.

[0018]

Embodiments of the present invention will be described below with reference to the accompanying drawings. FIG. 1 is an overall configuration diagram of an electric power steering apparatus according to the present invention. The electric power steering apparatus includes a rack and pinion mechanism 5 provided in a steering gear box 4 via a connecting shaft 3 having universal joints 3a and 3b on a steering shaft 2 provided integrally with a steering wheel 1. The manual steering force generating means 6 is constituted by being connected to the pinion 5a.

The rack shaft 7 is provided with rack teeth 7a meshing with the pinion 5a, and reciprocates by these meshing.
The left and right front wheels 9 as rolling wheels are connected to both ends thereof via tie rods 8. In this way, the front wheel 9 is rolled through the normal rack and pinion type steering to change the direction of the vehicle when the steering wheel 1 is steered.

In order to reduce the steering force by the manual steering force generating means 6, a motor 10 for supplying a steering assist force is arranged coaxially with the rack shaft 7, and a ball screw mechanism provided substantially parallel to the rack shaft 7. The steering assist force is converted into a thrust force via 11 and acts on the rack shaft 7.

The rotor of the motor 10 has a helical drive side on the drive side.
A gear 10a is provided integrally, and the drive-side helical gear 10a is meshed with a driven-side helical gear 11a provided integrally at the shaft end of the screw shaft of the ball screw mechanism 11. The nut of the ball screw mechanism 11 is connected to the rack shaft 7.

The steering gear box 4 has a steering torque sensor 12 for detecting a manual torque acting on the pinion 5a, and the steering shaft 2 has a steering torque corresponding to the rotation speed of the steering shaft 2. A steering rotation speed sensor 13 is provided, and a torque signal T and a steering rotation speed signal N are provided to the control unit 15. Further, a vehicle speed sensor 14 for detecting a vehicle speed signal V corresponding to the vehicle speed is also provided, and provides the vehicle speed signal V to the control unit 15.

In this embodiment, the steering wheel 1 and the front wheel 9 as a steered wheel are mechanically connected, and a torque signal T detected by a steering torque sensor 12 and a steering rotation detected by a steering rotation speed sensor 13 are used. The motor control obtained by processing the speed signal N, the torque signal T and the vehicle speed signal V detected by the vehicle speed sensor 14, or the combination signal of the torque signal T, the steering rotation speed signal N and the vehicle speed signal V by the control means 15. The motor 10 is PWM-driven by the signal Do (for example, a PWM signal) via the motor driving means 16 (for example, a bridge circuit using an FET), and is suitable for the going state and the returning state of the steering wheel 1 operation corresponding to the running state. It is configured to obtain a steering assist force that is high.

FIG. 2 shows an embodiment of the steering torque sensor, the steering rotation speed sensor and the vehicle speed sensor. (A) to (c)
The figure shows an example in which the steering torque sensor 12 is constituted by a differential transformer, the steering rotational speed sensor 13 is constituted by a DC generator such as a tacho generator, and the vehicle speed sensor 14 is constituted by a speedometer constituted by a rotating disk having a slit and a photocoupler. Show.

The steering torque sensor 12 outputs a torque signal (for example, a vector amount in the right direction T1 and the left direction T2) according to the steering rotation direction and the torque, and the steering rotation speed sensor 13 outputs a signal (for example, a signal corresponding to the rotation direction and the rotation speed). , The rightward direction N1 and the leftward direction N2), and the vehicle speed sensor 14 outputs a vehicle speed signal V1 (scalar amount) corresponding to the vehicle speed.

FIG. 3 shows an embodiment of the motor driving means constituted by the FET bridge. The motor driving means 16 is composed of an interface circuit 16A and a bridge circuit composed of four FETs (field effect transistors), and outputs a motor driving signal Mo for driving the motor 10 based on the motor control signal Do. The interface circuit 16A
The motor control signal Do input to the
Is formed from a direction signal for controlling the rotation direction of the motor 10 and a PWM signal for controlling the driving amount (driving torque and rotation speed) of the electric motor 10. For example, when the electric motor 10 is rotated clockwise, the FET Q1 is turned on by the direction signal, The gate of the FET Q3 is controlled by the duty ratio. On the other hand, when the motor 10 is rotated to the left, the FET Q4 is turned on by the direction signal, and the gate of the FET Q2 is controlled by the PWM signal. Further, FET Q1 and FET Q4 or FE
It is also possible to control so that the input terminals of the electric motor 10 are short-circuited by simultaneously turning on the TQ2 and the FET Q3 to apply electromagnetic braking.

[0027] FIG. 4 is a schematic block diagram of an electric power steering apparatus according to claim 1. The configuration shown in the figure relates to an electric power steering device that controls a motor control signal based on a steering torque and a steering rotation speed. In FIG. 4, the electric power steering device includes:
A steering torque sensor 12, a steering rotational speed sensor 13,
It comprises control means 15, electric motor driving means 16, and electric motor 10. The steering torque sensor 12 and the steering rotation speed sensor 13 are, for example, respectively shown in FIG.
The motor driving means 16 is constituted by a DC generator such as a differential transformer and a tachogenerator shown in FIG.
Consists of a bridge.

The control means 15 is basically composed of a microprocessor and comprises a steering state detecting means 17 and a motor control signal determining means 18. The torque signal T detected by the steering torque sensor 12 and the steering signal detected by the steering rotational speed sensor 13 are detected. Based on the absolute value of the rotation speed signal N, a torque control amount D _T corresponding to the torque signal T and a rotation speed control amount D _N corresponding to the steering rotation speed signal _N are converted.
The going state or the returning state of the steering wheel 1 is determined from the directions of the torque signal T and the steering rotation speed signal N, respectively, and the going state is a motor control signal (D _T -D _N ).
In the return state, the motor control signal (D _T + D _N ) is provided to the motor driving means 16 as the motor control signal Do.

The control means 15 includes an A / D conversion means (not shown) and a direction determination means (not shown).
Signal T detected by the motor and the steering rotational speed sensor 13
Converts the absolute value of the detected steering rotation speed signal N into a corresponding digital value, and detects the direction as an F and G flag. Further, the control unit 15 includes an output unit (not shown), and outputs a motor control signal (D _T −D _N ) and a motor control signal (D _T + D _N ) to a motor suitable for the motor drive unit 16 to drive the motor 10. Control signal Do, for example, PW
It is configured to convert to an M signal and output.

The steering detecting means 17 detects the going state or the returning state of the steering wheel 1 based on the direction flag F of the torque signal and the flag G of the steering rotational speed signal N. Switches the steering state signal St corresponding to the state such as the L level to the switching unit (SW
1) Supply to 21. The detection of the forward state or the return state is performed, for example, by determining the sign of the flag F and the sign of the flag G.
G) is the forward state, and if the signs of the flags F and G do not match (F （G), the state is the return state.

The motor control signal determining means 18 includes a torque control amount conversion unit 19A, a rotation speed control amount conversion unit 19B, a return control amount calculation unit 20A, a forward control amount calculation unit 20B, and a switching unit (SW1) 21. The torque control amount conversion unit 19A includes a memory such as a ROM, and sets a torque control amount D which is a motor control amount corresponding to the steering torque T as shown in Table 1 of FIG. The data of _T is stored in a memory in advance, and the torque control amount _DT corresponding to the input of the digitally converted torque signal _T is selected to output the torque control amount signal _DT .

The rotation speed control amount conversion unit 19B includes a memory such as a ROM, and sets a steering rotation speed N set based on experimental results or theoretical calculations, for example, as shown in Table 4 in FIG. 13 or Table 5 in FIG. The rotation speed control amount D _N (D _{N +} , D _N− ), which is the corresponding motor control amount, is stored in a memory in advance, and the rotation speed control amount D corresponding to the digitally converted steering rotation speed signal N input is stored. select _N configured to output a rotational speed control amount signal D _N.

[0033] Returning control amount calculation unit 20A is configured by operation means consisting of an adder or the like, the motor control signal in the state back by adding a rotational speed control amount signal D _N and the torque control amount signal D _T (D _T + D _N ), And the outgoing control amount calculation section 20B is constituted by calculation means including a subtractor and the like, and the torque control amount signal D _T
The deviation of the rotational speed control amount signal D _N calculates and outputs a motor control signal forward state (D _T -D _N).

The switching section (SW1) 21 has a switch function of software program control. Based on the steering state signal St supplied from the steering state detection means 17, for example, when the going state is detected at H level, the motor control signal (D _T -D _N ) is selected (solid line of SW1), and when the return state is detected, the motor control signal (D
_T + D _N ) is selected and output as the motor control signal Do.

[0035] Thus, the control unit 15, the steering direction of rotation the motor control signal Do of the deviation between the torque control amount D _T in the forward state of the steering wheel 1 speed control quantity D _N (D _T -D _N) decay corrected by forming in the same direction, the sum of the return state and the torque control amount D _T rotational speed control amount D _N (D _T
+ D _N ) since the motor control signal Do is formed in the direction opposite to the steering rotation direction and the attenuation correction is performed.
, A steering assist force that decreases as the steering rotation speed N increases is obtained, and a braking force that increases as the steering rotation speed N increases from the electric motor 10 is obtained in the return state. Note that the damping correction means that a steering rotation speed component (a control amount corresponding to the rotation speed control amount) in a direction opposite to the steering rotation direction is given to the torque control amount.

Further, the control unit 15, the rotational speed control of the state forward rotational speed control amount D _N of the rotational speed control quantity conversion unit 19B is a table 5 shown in FIG. 14 D _N-, the return state in FIG. 13 leave prepared respectively as ₊ rotation speed control amount D _N of table 4 shown, the state forward the motor control signal (D _T
−D _N− ) and the return state can be (D _T + D _{N +} ).

[0037] FIG. 5 is a schematic block diagram of an electric power steering apparatus according to claim 2. The configuration shown in the figure relates to an electric power steering device that controls a motor control signal based on steering torque and vehicle speed. In FIG. 5, the electric power steering device includes a steering torque sensor 12, a vehicle speed sensor 14, a control unit 22, a motor driving unit 16, and the motor 10. The steering torque sensor 12 and the vehicle speed sensor 14 are respectively
For example, it is composed of a differential transformer shown in FIGS. 2A and 2C, a speedometer composed of a rotating disk having a slit and a photocoupler, and the motor driving means 16 is an FE shown in FIG.
It consists of a T-bridge.

The control means 22 is basically composed of a microprocessor and includes a steering state detecting means 17 and a motor control signal determining means 23. The torque signal T detected by the steering torque sensor 12 and the vehicle speed signal V detected by the vehicle speed sensor 14 are provided. Of the motor control signal D _T corresponding to the torque signal T and the damping coefficient R corresponding to the vehicle speed signal V based on the absolute values of
v, and multiplying the damping coefficient Rv by a predetermined control amount in the going state and the returning state (for example, a constant value of D _N− and D _{N +} control amount related to the steering rotation speed N) to obtain the going state of the steering wheel 1. Alternatively, a return state is determined, and a motor control signal (D _T −Rv * D _N− ) is used for a going state, and a motor control signal (D _T + Rv * D _{N +} ) is used for a motor control signal Do for a return state. To provide.

The control means 22 includes A / D conversion means (not shown) as in FIG. 4, and corresponds to the absolute value of the torque signal T detected by the steering torque sensor 12 and the absolute value of the vehicle speed signal V detected by the vehicle speed sensor 14. Convert to digital value.
Further, the control unit 22 comprises an output unit (not shown) as in FIG. 4, the motor system signal (D _T -Rv * D _N-) and the motor control signal _{(D T + Rv * D N} +), the electric motor driving unit 16 The motor 10 is configured to be converted into a motor control signal Do suitable for driving the motor 10, for example, a PWM signal and output.

The steering state detecting means 17 provides the switching section 21 of the motor control signal determining means 23 with a steering state signal St of H level when the steering wheel 1 is in the forward state and L level when the steering wheel 1 is in the return state.

The motor control signal determining means 23 includes a torque control amount conversion unit 19A, a damping coefficient conversion unit 24, a control amount storage unit 25, multipliers 26A and 26B, a subtracter 27A, and an adder 2.
7B, a switching unit 21 is provided. Torque control amount converter 19A
Has the same configuration as that of FIG. 4, selects a torque control amount _DT corresponding to the input of the digitally converted torque signal _T, and outputs a torque control amount signal _DT .

The damping coefficient conversion unit 24 has a memory such as a ROM, and stores in advance data of a damping coefficient Rv corresponding to the vehicle speed V as shown in Table 2 of FIG. Memorize it in memory,
An attenuation coefficient Rv corresponding to the digitally converted vehicle speed signal V input is selected to output an attenuation coefficient signal Rv.

The control amount storage unit 25 is composed of a memory such as a ROM, and includes a going control amount storage unit 25A and a returning control amount storage unit 25B. The going-time control amount storage unit 25A and the return-time control amount storage unit 25B store a predetermined control value of a predetermined value, for example, control values D _N− and D _{N +} of a constant value related to the steering rotation speed N. , Based on the steering state signal St from the steering state detecting means 17. The multiplier 26A and the multiplier 26B
The constant values D _N− and D _{N +} are respectively multiplied by the attenuation coefficient Rv and output to the subtracter 27A and the adder 27B.

The subtractor 27A subtracts the output of the multiplier 26A (Rv * D _N-) from the torque signal T corresponding motor control signal D _T, whereas the adder 27B in the torque signal T corresponding motor control signal D _T The output (Rv * D _{N +} ) of the multiplier 26B is added and output to the switching unit 21. The switching unit 21 receives the steering state signal St from the steering state detection unit 17.
The forward state is switched to the subtractor 27A side and the return state is switched to the adder 27B side, and the motor control signals (D _T -Rv * D _N− ) and (D _T + Rv * D _{N +} ) corresponding to each state.
Is output to the motor drive means 16 as the motor control signal Do, and the motor 10 is driven via the motor drive means 16.

[0045] Thus, the control means 22, and the torque control amount D _T in the forward state of the steering wheel 1, multiplied by the _N- control amount D of a fixed value to the attenuation coefficient Rv (Rv * D _N-)
Deviation between (D _T -Rv * D _N-) a motor control signal Do is formed in the steering the same direction as the rotation direction of the torque control amount D _T is the return state, the control amount D of a fixed value to the attenuation coefficient Rv _Since the motor control signal Do of the sum (D _T + Rv * D _{N +} ) of (Rv * D _{N +} ) multiplied by _{N +} is formed in the direction opposite to the steering rotation direction, the going state decreases as the vehicle speed V increases from the motor. In the return state, a braking force that increases as the vehicle speed V increases from the electric motor is obtained.

FIG. 6 is a block diagram of a main part of the electric power steering apparatus according to the third and fourth aspects. The configuration shown in the figure relates to an electric power steering device that controls a motor control signal based on steering torque, steering rotation speed, and vehicle speed. Further, the steering torque sensor 12, the steering rotation speed sensor 13, and the vehicle speed sensor 1 shown in FIG.
4. Since the motor driving means 16 and the motor 10 are the same as those described in FIG. 4 or FIG. 5, the description is omitted, and the control means 29 will be described.

The control means 29 is basically composed of a microprocessor and comprises the steering state detecting means 17 and the motor control signal determining means 30. Here, the steering state detecting means 17 has the same configuration as that of FIG. 4 and detects the forward state or the return state of the steering wheel 1 based on the sign of the flag F of the steering torque T and the sign of the flag G of the steering rotational speed N. It outputs a steering state signal St.

The motor control signal determination means 30 includes a rotation speed shift amount conversion unit 31A, a damping coefficient conversion unit 31B, a subtractor 32, a switching unit (SW2) 33, and a torque control amount conversion unit 3.
4. Control subtraction amount converter 35A, control addition amount converter 35
B, multipliers 36A and 36B, return control amount calculation unit 37A,
An outgoing control amount calculation unit 37B and a logical sum switching unit 38 are provided.

The rotation speed shift amount conversion unit 31A and the damping coefficient conversion unit 31B have a memory such as a ROM, and correspond to the vehicle speed V, for example, as shown in Table 3 in FIG. Steering speed shift amount Hv, and vehicle speed V as shown in Table 2 in FIG.
Is stored in a memory in advance, and a steering rotation speed shift amount Hv and a damping coefficient Rv corresponding to the digitally converted vehicle speed signal V are selected, and a steering rotation speed shift amount signal Hv, Attenuation coefficient signal Rv
Is output.

The subtractor 32 calculates the deviation No (= N−H) between the digitally converted steering rotational speed signal N and the steering rotational speed shift amount signal Hv from the rotational speed shift amount converter 31A.
v), and supplies the deviation signal No to the switching unit (SW2) 33 and the correction prohibiting unit 39. Switching unit (SW2) 3
Reference numeral 3 has a switch function of software program control, and switches the switch SW2 based on the steering state signal St. For example, if the level is H level (forwarding state: F = G), the control subtraction amount conversion unit 35A side, L level (return state: If F ≠ G), the deviation signal No is provided to the control addition amount converter 35B side.

The control subtraction amount conversion unit 35A and the control addition amount conversion unit 35B have a memory such as a ROM, and are respectively set based on experimental results or theoretical calculations.
The rotation speed control amount D _N− corresponding to the steering rotation speed N (No) as in the table 5 of FIG. 4 and the rotation speed control amount D _{N +} corresponding to the steering rotation speed N (No) as in the table 4 of FIG.
Is stored in a memory in advance, and the steering rotational speed N
The rotation speed control amount D _N- corresponding to o, the rotation speed control amount D _{N +}
And outputs a rotation speed control amount signal D _N− and a rotation speed control amount signal D _{N +} to the multipliers 36A and 36B, respectively.

The multipliers 36A and 36B respectively provide a rotational speed control amount signal D _N− and a rotational speed control amount signal D _{N +}
Is multiplied by the attenuation coefficient signal Rv, and the operation result (Rv *
D _N− ) and (Rv * D _{N +} ), respectively.
7B, supply to the return control amount calculation unit 37A.

Returning based on the torque control amount signal D _T and (Rv * D _{N +} ) and (Rv * D _N− ) supplied from the same torque control amount converter 34 as the torque control amount converter 19A of FIG. The control amount calculation unit 37A and the going control amount calculation unit 37B respectively return the motor control signal (D _T + Rv *) in the return state.
_{DN +} ), the motor control signal in the going state ( _DT- Rv *).
D _N− ), and either one is selected via a logical sum switch (SW3) 38 in accordance with the going state or the returning state of the steering system, and is output as a motor control signal Do.

The correction prohibiting means 39 includes a judging means such as a comparator. When the operation result No (= N−Hv) of the subtractor 32 is smaller than the reference value Ks (for example, 0), the prohibition signal Ko is converted into a control subtraction amount. The steering rotation speed signal No, which is a deviation signal provided to the control unit 35A and the control addition amount conversion unit 35B and input to the control subtraction amount conversion unit 35A and the control addition amount conversion unit 35B from the subtractor 32, is forcibly set to 0. Control to do. When the steering rotation speed signal No is set to 0, the motor control signal Do becomes only the torque control amount signal _{DT in} both the forward state and the return state, and the motor control signal determination means 30
Prohibits correction.

As described above, the motor control signal determining means 30
Sets the steering rotation speed N to No (= N−H) in accordance with the vehicle speed V.
v), and in the forward state, subtract a value (Rv * D _N− ) obtained by multiplying the rotation speed control amount DN ₋ damping coefficient Rv corresponding to the steering rotation speed No from the torque control amount _DT (D _T −
Rv * D _N− ) to form a motor control signal Do in the same direction as the steering rotation direction, and in the return state, multiply the rotation speed control amount _{DN +} corresponding to the steering rotation speed No by the damping coefficient Rv (Rv * D _{N +} ) is added to the torque control amount D _T to form the motor control signal Do in the direction opposite to the steering rotation direction, so that the going state decreases as the vehicle speed V and the steering rotation speed N increase from the motor. Helping power,
In the return state, the vehicle speed V and the steering rotation speed N
Increases, the braking force that increases is obtained.

FIG. 7 is a block diagram of a main part of an electric power steering apparatus according to a fifth aspect . 7, an electric power steering apparatus includes a motor current detecting means 4 for detecting a motor current I _M and a motor voltage V _M of the motor 10 instead of the steering rotation speed sensor 13 in FIG.
And 2, a motor state detecting means 41 comprising a motor voltage detection means 43 is provided, a structure in which a steering speed calculation means 40 for calculating a steering speed N _M of the control unit 29 detects the steering speed N directly Instead, a steering rotation speed N _M corresponding to the steering rotation speed N _M is obtained by calculation.

The steering rotation speed N _M of the motor 10 is determined by the impedance Z _L corresponding to the inductance L of the motor 10.
(Z _L = 2πf * L, and since it is a DC, the frequency is changed from f = 0 to Z _L = 0), and the motor current I _M ,
Motor voltage V _M, is approximately represented by the number 1 from the induced voltage coefficient of the motor K _M and the motor internal resistance R _M.

[0058]

[Number 1] _{N M = (V M -R M} * I M) / K M

[0059] motor current detector 42 and the motor voltage detection means 43 detects a motor voltage V _M to be generated across the motor current I _M and the electric motor 10 actually flowing to the motor 10 from the motor drive unit 16, control unit 29 The motor current _IMO and the motor voltage _VMO, which have been converted into digital values via A / D conversion means (not shown) provided in, are provided to the steering rotation speed calculation means 40.

[0060] steering speed calculating means 40 performs calculation Equation 1 reads the induced voltage coefficient K _M and the motor internal resistance R _M of the previously stored motor in a memory such as a ROM,
Calculates the steering speed N _M provides a steering rotational speed signal N _M to the subtracter 32.

As described above, the motor current I _M and the motor voltage V _M actually generated in the motor 10 are detected by the motor state detection means 41 and fed back, and the steering rotation speed N _M is calculated by the steering rotation speed calculation means 40. And subtracter 3
Output 2, it is possible to perform the same operation as that in FIG. 6 based on the steering speed N _M.

Next, the operation of the configuration shown in FIG. 6 will be described based on an operation flowchart. FIG. 8 is an operation flow chart of the control means in FIG. 6 according to an embodiment. States Po to P20 show respective operation states of the control means. When a key switch (not shown) of an ignition key is turned on, power is applied to the control means 29 and the operation starts. (State Po) First, a microprocessor constituting the control means 29 starts a control operation, sends a control signal such as a power-on reset signal to each component, performs an initial reset, and initializes (state P)
Execute 1).

When the steering wheel 1 is operated, the steering torque signals T1 and T2 including the torque value of the analog value detected by the steering torque sensor 12 and the steering rotation direction are read (state P2), and are read via the A / D converter and the like. Is converted into a digital torque signal T and a flag F indicating the direction of the steering torque (state P3). The digital torque signal T is converted into a torque control amount _DT based on data of a table 1 (see FIG. 10) preset in a memory in the torque control amount conversion unit 34 and output (state P4).

Subsequently, the analog vehicle speed signal V1 detected by the vehicle speed sensor 14 is converted into a digital vehicle speed signal V via an A / D converter or the like (state P5). The data of Table 2 (see FIG. 11) preset in the memory of the attenuation coefficient conversion unit 31B and the data of Table 3 (see FIG. 12) preset in the memory of the rotation speed shift amount conversion unit 31A Based on this, they are converted into an attenuation coefficient Rv and a steering rotation speed shift amount Hv corresponding to the vehicle speed signal V and output (states P6 and P7).

Similarly, the steering rotation speed signals N1 and N2 including the analog rotation speed and rotation direction detected by the steering rotation speed sensor 13 are read (state P8), and A / A
A digital value of the steering rotation speed signal N via a D conversion unit, etc.
And a flag G indicating the rotation direction is output (state P9).

Next, the difference No (= N−H) between the steering rotation speed signal N and the steering rotation speed shift amount Hv is calculated by the subtractor 32.
v) is calculated, and the steering rotation speed signal N (= N
o) is output and the correction N
It is determined whether or not o exceeds 0 (No> 0) (No ≦ 0). If No> 0, the steering rotation speed signal N (= N
o = N−Hv) is output, and when No ≦ 0, N (=
No) = 0 is output (state P10, state P11, state P10 ').

Subsequently, the sign determination of the flag F indicating the steering torque direction converted in the state P3 and the flag G indicating the steering rotation direction converted in the state P9 is performed by the steering state detecting means 17 (state P12). Signs match (F =
G), the steering state detecting means 17 determines that the state is the going state and controls the switching of the switching section 33, and sends the steering rotation speed signal N (= No) provided from the subtractor 32 to the control subtraction amount conversion section 35A. , steering rotational speed signal N (= No) is converted rotational speed control amount D to _N- based on the data of the control subtraction quantity converter memory preset table in 35A 5 (see FIG. 14) (state P13 ), And multiplied by the attenuation coefficient Rv in the multiplier 36A to obtain (D _N− * Rv) (state P14). The calculation result (D _N− * Rv) is replaced with D _N−, and the going control amount calculation unit 37B compares the level with the torque control amount D _T converted in the state P4 (D _T −D _N− ) (state). P15), when the torque control amount D _T follows the rotational speed control amount _{D N- (= D N- * Rv} ) (D T ≦ D N-), D T
= 0 (state P15 '), and the motor control signal D _T (= D
o) is output. On the other hand, when the torque control amount D _T exceeds the rotation speed control amount D _N− (= D _N− * Rv) (D _T >
Motor control signal D _T (= D _N− ), (D _T −D _N− * Rv)
Do) is output.

When the signs do not match (F ≠ G),
The steering state detecting unit 17 determines that the vehicle is in the return state, and controls the switching of the switching unit 33, sends the steering rotation speed signal N (= No) provided from the subtractor 32 to the control addition amount conversion unit 35B, and outputs the steering rotation speed signal. N (= No) is a table 4 (FIG. 1) preset in a memory in the control addition amount conversion unit 35B.
3) is converted into a rotational speed control amount D _{N +} (state P17), and is multiplied by the attenuation coefficient Rv by the multiplier 36A to obtain (D _{N +} * Rv) (state P18). The calculation result (D _{N +} * Rv) is replaced with D _{N +,} and the torque control amount D converted in the state P4 in the return control amount calculation unit 37A.
_T (state P19), and the operation result (D _T + D _{N +} * R
v) is set to D _T and the motor control signal D _T (= Do) is output.

FIG. 9 is an operation flowchart of another embodiment of the control means of FIG. In FIG. 9, states P15 and P1 in FIG.
The difference is that 5 'has been deleted. When the torque control amount D _T is equal to or less than the rotation speed control amount D _N− (= D _N− * Rv) (D _T ≦
D _N− ) is a motor control signal D _T (for changing the rotation direction of the motor 10 by changing the sign of the flag F indicating the steering torque direction and changing the drive of the FET constituting the motor drive means 16). = Do), and controls to drive the braking torque corresponding to the motor control signal _DT in the reverse direction.

FIG. 16 is an operation flowchart of an embodiment of the control means of the electric power steering apparatus according to the present invention.
P0 to P23 indicate each state of the operation flow. An ignition switch (not shown) is turned on to supply power to the control device and other circuits (state P0), a microprocessor constituting the control device is initialized, and RA
The memory such as M, the operation unit, the processing unit, and the like are reset (state P1).

Next, in state P2, the steering torque signals T1, T
2 is read, and the action direction and magnitude of the steering torque are calculated in state P3 based on the steering torque signals T1 and T2,
The setting of the flag F indicating the direction of application of the torque and the conversion to the absolute value T of the torque are performed and stored in the memory.

Subsequently, in the state P4, the contents of the memory having the absolute value T of the steering torque as an address are stored in Table 1 (FIG. 17).
See). Table 1 shows a torque control amount D _T corresponding to the absolute value T of the steering torque shown in FIG.
Is stored. Further, in the state P5, the contents of the memory having the absolute value T of the steering torque as an address are stored in Table 2.
(See FIG. 18). Table 2 contains Table 1
The damping coefficient R1 corresponding to the absolute value T of the steering torque shown in FIG. 8 is stored. The damping coefficient R1 is a ratio of the magnitude of the amount of damping of the steering system, and is constant within a range where the steering torque T is small. It is set in advance to be kept at a value and to decrease as the steering torque T increases.

In the state P6, the vehicle speed signal V1 is read, and in the states P7 and P8, the vehicle speed V corresponding to the vehicle speed signal V1 is calculated. The contents of the memory having the vehicle speed V as an address are called from the table 3 (see FIG. 19). It is. Table 3 stores the damping coefficient Rv corresponding to the vehicle speed V as shown in FIG. 19, and this damping coefficient Rv is a ratio of the magnitude of the damping amount of the steering system. It is set in advance to be kept at a value and to increase as the vehicle speed V increases.

Next, in state P9, the steering rotation speed signal N
1 and N2, the magnitude and action direction of the steering rotation speed are calculated in state P10 based on the steering rotation speed signals N1 and N2, and the rotation direction flag G indicating the steering rotation direction and the absolute value of the steering rotation speed (steering rotation speed). Number) N and stored.

Subsequently, in the state 11, the flag F indicating the direction of operation of the steering torque is compared with the flag G indicating the direction of operation of the steering rotation. If the flag F and the flag G match (F = G), it is determined that a forward operation of the steering system has been performed, and the routine shifts to the state P12. See). The table 4 is stored rotational speed control amount D _N-that such corresponding to the steering rotational speed N as shown in FIG. 20, increasing the rotational speed control amount D _N-is with the steering rotational speed N increases Is set in advance. It should be _noted that the rotational speed control amount D _N− is changed to a torque control amount D _{T in} a state described later.
By reducing the torque control amount _DT in accordance with the steering speed N during the forward operation, damping can be given to the steering system.

[0076] multiplied by the state P13 in rotational speed control quantity D _{N-attenuation} coefficient R1 and damping coefficient Rv, the optimal value corresponding to the steering torque and the vehicle speed are stored as a rotation speed control quantity D _N-. In the state P14, comparison of the rotational speed control quantity D _N-and the torque control amount D _T stored in the state P13 is performed, if the torque control amount D _T is determined to be greater than the rotational speed control amount D _N- moves to (D _T ≧ D _N-) state in P20, the rotational speed control amount D _N-deviation between the torque control amount D _T is calculated, this calculation result is outputted to the torque control amount D _T ( (State P20).

On the other hand, when it is determined in state P14 that the torque control amount _DT is smaller than the rotation speed control amount _DN- (D _T
In <D _N− ), the state shifts to the state P15, and the contents of the memory having the vehicle speed V as an address are called from the table 6 (see FIG. 22). The table 6 stores a subtraction signal threshold value D _L corresponding to the vehicle speed V as shown in FIG. 22. The subtraction signal threshold value D _L is set to 0 when the vehicle speed V is in the low vehicle speed region and the middle vehicle speed region. The predetermined value is set in advance only in the high vehicle speed region. Note that subtraction signal threshold D _L is in the high vehicle speed region indicates the maximum value of the assist torque in the steering torque T and the opposite direction, as it is clear from FIG. 22 in the low speed region of the steering torque T and the opposite direction It is configured not to perform assist.

[0078] Then, calculates the rotational speed control amount D _N-deviation between the torque control amount D _T in a state P16, the calculation result is stored as a negative motor control signal D _T, a negative in the state P17 of the motor control signal D _T and the subtraction signal threshold D _{L of} state P15
Is multiplied by -1 (-D _L ), and when the absolute value of the motor control signal D _T is smaller than the absolute value of the subtraction signal threshold D _L (| D _T | <D _L ) Has a motor control signal D
The assist in the reverse direction corresponding to _T is executed.

[0079] On the other hand, when the absolute value of the motor control signal D _T in a state P17 is determined to be greater than the absolute value of the subtraction signal threshold _{D L (| D T | ≧} D L) to transition to a state P18 is state P19 limits the motor control signal D _T is the subtraction signal threshold D _L is the maximum value of the assist torque in the reverse direction and
Migrated, assist in the reverse direction corresponding to the subtraction signal threshold D _L is executed.

When it is determined in the state P11 that the steering system is to be returned (F ≠ G), the state P21 to the state P23 are controlled. The state P21 to the state P
In the control of 23, the damping control in the direction opposite to the steering torque T is not executed. In this way, by performing the control in FIG. 16, a larger attenuation corresponding to the vehicle speed can be applied to the steering system.

[0081]

As described above, according to the present invention, the electric power steering apparatus according to claim 1, the motor control signal to the steering direction of rotation in the same direction of the deviation between the torque control amount to the forward state of the steering wheel rotation speed control amount In the return state, the motor control signal of the sum of the torque control amount and the rotation speed control amount is formed in the direction opposite to the steering rotation direction, so in the forward state, the steering decreases from the motor as the steering rotation speed increases. In the assisting and returning states, it is possible to obtain a braking force from the electric motor that increases as the steering rotational speed increases.

[0082] The electric power steering apparatus according to claim 2, forward state of the steering wheel torque control amount and the steering rotates the motor control signal of the difference between the value obtained by multiplying the controlled variable of a fixed value to the attenuation coefficient The return state is formed in the opposite direction to the steering rotation direction because the return state forms a motor control signal of the sum of the torque control amount and the value obtained by multiplying the damping coefficient by a constant control amount in the direction opposite to the steering rotation direction. It is possible to obtain a steering assist force that decreases as the vehicle speed increases from the electric motor, and a braking force that increases as the vehicle speed increases from the electric motor in the return state.

Further, the electric power steering device according to the fourth and fifth aspects corrects the steering rotational speed in accordance with the vehicle speed so as to decrease the steering rotational speed. Is subtracted from the torque control amount to form a motor control signal in the same direction as the steering rotation direction. In the return state, the value obtained by multiplying the rotation speed control amount corresponding to the steering rotation speed by the damping coefficient is the torque control amount. To generate a motor control signal in the direction opposite to the steering rotation direction, so that the steering assist force decreases as the vehicle speed and the steering rotation speed increase from the motor in the going state, and the vehicle speed and steering rotation from the motor in the return state. It is possible to obtain a braking force that increases as the speed increases. Also,
Since the motor control signal determination means is provided with a correction prohibition means,
Correction can be prohibited.

Further, in the electric power steering apparatus according to the fifth aspect , the motor current and the motor voltage actually generated in the motor are detected by the motor state detecting means and fed back, and the steering rotational speed is calculated by the steering rotational speed calculating means. Since the calculation is performed, the same effect as that of the fifth aspect can be obtained.

Accordingly, the steering assist force of the steering system can be reduced and the braking force of the steering system can be increased in accordance with the increase in the steering rotation speed, the vehicle speed, or the steering rotation speed and the vehicle speed. The steering characteristics and return characteristics of the vehicle can be improved, and stable steering performance can be obtained.

[Brief description of the drawings]

FIG. 1 is an overall configuration diagram of an electric power steering device according to the present invention.

FIG. 2 shows an embodiment of a steering torque sensor, a steering rotation speed sensor, and a vehicle speed sensor.

FIG. 3 shows an embodiment of a motor driving means constituted by an FET bridge.

FIG. 4 is a block diagram of a main part of the electric power steering apparatus according to claim 1;

FIG. 5 is a block diagram of a main part of an electric power steering apparatus according to claim 2;

FIG. 6 is a block diagram of a main part of an electric power steering apparatus according to claims 3 and 4;

FIG. 7 is a block diagram of a main part of an electric power steering apparatus according to claim 5;

8 is an operation flowchart of an embodiment of the control means of FIG. 6;

FIG. 9 is an operation flowchart of another embodiment of the control means of FIG. 6;

FIG. 10 is a characteristic diagram of a steering torque T-torque control amount _DT (Table 1).

FIG. 11 is a graph showing a relationship between a vehicle speed V and a damping coefficient Rv (Table 2).

FIG. 12 is a diagram showing a relationship between a vehicle speed V and a steering rotation speed shift amount Hv (Table 3).

FIG. 13 is a characteristic diagram of a steering rotational speed N-a rotational speed control amount _{DN +} (Table 4).

FIG. 14: Steering rotation speed N—rotation speed control amount DN _— characteristic diagram (Table 5)

[15] a steering rotational speed N- rotational speed control amount D _N- characteristic diagram

FIG. 16 is an operation flowchart of an embodiment of the control means of the electric power steering apparatus according to the present invention.

FIG. 17 is a characteristic diagram of steering torque T-torque control amount _DT (Table 1).

FIG. 18 is a characteristic diagram of steering torque T-damping coefficient R1 (Table 2).

FIG. 19 is a diagram showing a relationship between a vehicle speed V and a damping coefficient Rv (Table 3).

FIG. 20: Steering rotation speed N-rotation speed control amount D _N- characteristic chart (Table 4)

FIG. 21 is a characteristic diagram of steering speed N—rotation speed control amount D _{N +} (Table 5).

FIG. 22 is a graph showing a vehicle speed-subtraction signal threshold value D _L characteristic (Table 6).

[Explanation of symbols]

1 ... steering wheel, 2 ... steering shaft, 3 ...
Connection shaft, 3a, 3b: universal joint, 4: steering gear box, 5: rack and pinion mechanism, 5a: pinion, 6: manual steering force generating means, 7: rack shaft, 7a: rack teeth, 8: tie rod, 9 … Front wheel, 10 electric motor, 10
a: Drive side helical gear, 11: Ball screw mechanism, 1
1b: driven helical gear, 12: steering torque sensor, 13: steering rotation speed sensor, 14: vehicle speed sensor, 1
5, 22, 29: control means, 16: motor drive means, 1
7: Steering state detecting means, 18, 23, 30: electric motor control signal determining means, 19A, 34: torque control amount conversion section, 19B: rotation speed control amount conversion section, 20A: return control amount calculation section, 20B: forward control Quantity operation units 21, 33,
38: logical sum switching unit (SW3), 24, 31B: damping coefficient conversion unit, 25: control amount storage unit, 25A: outgoing control amount storage unit, 25B: return control amount storage unit, 26A, 26
B, 36A, 36B ... multiplier, 27A, 32 ... subtractor,
27B: adder, 31A: rotational speed shift amount converter, 3
5A: control subtraction amount converter, 35B: control addition amount converter,
37A: Return control amount calculation unit, 37B: Forward control amount calculation unit, 40: Steering rotation speed calculation unit, 41: Motor state detection unit, 42: Motor current detection unit, 43: Motor voltage detection unit, Do: Motor control signal _{, D N, D N-, D} N + ... rotational speed control amount, D _T ... torque control amount, Hv ... steering speed shift, I _M ... motor current, K _M ... induced voltage coefficient, K
o ... inhibit signal, Mo ... motor drive signal, N ... steering rotational speed signal, N _M ... steering rotational speed, R _M ... motor internal Resistance, R
v ... attenuation coefficient, St ... steering state signal, T ... steering torque signal, V ... vehicle speed signal, V _M ... motor voltage.

Continuation of the front page (72) Inventor Shigeru Yamawaki 1-4-1 Chuo, Wako-shi, Saitama Prefecture Honda R & D Co., Ltd. (56) References JP-A-62-238165 (JP, A) JP-A-4-362476 (JP, a) JP Akira 61-98675 (JP, a) JP flat 3-176272 (JP, a) JP Akira 63-291769 (JP, a) (58 ) investigated the field (Int.Cl. ⁷ , DB name) B62D 6/00

Claims (5)

(57) [Claims] An electric power steering apparatus for reducing the steering force by applying the power of an electric motor to a steering system, wherein a steering torque detecting means for detecting a steering torque of the steering system and a steering rotation speed of the steering system are detected. A steering rotational speed detecting means, a steering state detecting means for detecting a forward state and a return state of the steering system, and an output signal of the steering torque detecting means when the steering state detecting means detects the forward state. A value corresponding to the output signal of the steering rotational speed detecting means is subtracted and corrected from the value, and when a return state is detected, the output signal of the steering rotational speed detecting means is changed to a value corresponding to the output signal of the steering torque detecting means. Motor control signal determining means for adding and correcting a value corresponding to the following, and based on an output signal of the motor control signal determining means. And a motor driving means for driving the electric motor Te, the forward state of the steering system the direction of steering torque
And the direction of the steering rotation coincide with each other.
Are not in agreement with each other . 2. An electric power steering apparatus in which the power of an electric motor is applied to a steering system to reduce a steering force. A steering torque detecting means for detecting a steering torque of the steering system, and a vehicle speed detecting means for detecting a vehicle speed. A steering state detecting means for detecting a forward state and a return state of the steering system; and, when the steering state detecting means detects the forward state, the vehicle speed detecting means determines a value corresponding to an output signal of the steering torque detecting means. The value corresponding to the output signal of the vehicle is subtracted and corrected, and when the steering state detecting means detects the return state, the value corresponding to the output signal of the steering torque detecting means corresponds to the output signal from the vehicle speed detecting means. A motor control signal determining means for adding and correcting the value; and And a motor driving means for driving the machine, the forward state of the steering system the direction of steering torque
Steering direction of the rotation is in a state that one Itasu, the return state
Are not in agreement with each other . 3. An electric power steering apparatus in which the power of an electric motor is applied to a steering system to reduce a steering force, wherein a steering torque detecting means for detecting a steering torque of the steering system, and a steering rotation speed of the steering system are detected. Steering speed detecting means for detecting, vehicle speed detecting means for detecting the vehicle speed,
A steering state detecting means for detecting a forward state and a return state of a steering system; and, when the steering state detecting means detects the forward state, the steering rotational speed detecting means from a value corresponding to an output signal of the steering torque detecting means. A value corresponding to the output signal of the vehicle speed is multiplied by a value corresponding to the output signal of the vehicle speed detecting means, and a value corresponding to the output signal of the steering torque detecting means is corrected to a value corresponding to the output signal of the steering torque detecting means. A motor control signal determining means for adding and correcting a value obtained by multiplying a value corresponding to the output signal of the steering rotational speed detecting means by a value corresponding to the output signal of the vehicle speed detecting means; and and a motor driving means for driving the electric motor Te, the forward state of the steering system the direction of steering torque
And the direction of the steering rotation coincide with each other.
Are not in agreement with each other . 4. When the output signal of the steering rotational speed detecting means is smaller than a predetermined value which decreases with an increase of the output signal of the vehicle speed detecting means, the subtraction correction and the addition are performed. The electric power steering apparatus according to claim 3, further comprising a correction prohibiting unit that prohibits the correction. 5. A motor state detecting means for detecting a motor voltage and a motor current of the electric motor instead of the steering rotational speed detecting means, and a steering for calculating a steering rotational speed based on an output signal of the motor state detecting means. 4. The electric power steering apparatus according to claim 1, further comprising a rotation speed calculating means.