JP3608833B2 - Electric power steering device - Google Patents

Description

[0001]
[Industrial application fields]
The present invention relates to an electric power steering apparatus that reduces the steering force of a driver by directly applying the power of an electric motor to a steering system.
[0002]
[Prior art]
As disclosed in Japanese Patent Application Laid-Open No. 6-171519 by the applicant of the present application, a conventional electric power steering device has a steering torque sensor disposed in a steering gear box and detects pinion steering torque generated by steering of a driver. Based on this steering torque, a target assist signal is generated to drive an electric motor provided in the steering system.
[0003]
Further, the conventional electric power steering device feeds back the actual assist amount output from the motor based on the target assist signal to the target assist signal, and drives the motor based on the deviation between the target assist signal and the actual assist amount. The actual assist amount is configured to converge stably on the target assist signal.
[0004]
FIG. 10 shows a block diagram of a main part of a conventional electric power steering apparatus.
In FIG. 10, a conventional electric power steering apparatus 60 includes a control unit 61 having a target assist signal generation circuit 62 and a deviation calculation circuit 63, a drive signal generation circuit 64, an assist amount detector 65, and an electric motor 66.
[0005]
The target assist signal generation circuit 62 of the control unit 61 is connected to a pinion torque signal T detected by a steering torque sensor 67 disposed in the steering gear box._PIs converted into a preset target assist signal Ta, and the target assist signal Ta is provided to the deviation calculating means 63.
[0006]
On the other hand, the steering assist force acting on the steering system by the electric motor 66 is detected by the assist amount detector 66 and provided to the deviation calculating means 63 as the actual assist amount signal Ad.
[0007]
A deviation ΔI (= Ta−Ad) between the target assist signal Ta and the actual assist amount signal Ad is calculated by the deviation calculating means 63, and the drive signal generating means 64 drives the motor 66 based on the deviation signal ΔI, so that the steering system has a target. The actual assist amount signal Ad equal to the assist signal Ta is applied, and the steering force of the driver is reduced.
[0008]
As described above, the conventional electric power steering device 60 has the pinion torque signal T detected by the steering torque sensor 67 arranged in the steering gear box._POn the basis of this, the steering assist force acting on the steering system of the electric motor 66 is set.
[0009]
[Problems to be solved by the invention]
A conventional electric power steering device 60 is configured by a pinion torque signal T by a steering torque sensor 67 disposed in a steering gear box._PFor detecting the pinion torque signal T_PDoes not include loads such as steering wheel inertia torque and viscous torque.
[0010]
In actual steering, the driver applies steering torque T to the steering wheel._SThis steering torque T_SIs the steering wheel inertia torque T_JAnd viscous torque T_DThe steering wheel starts to rotate by overcoming the pinion torque T to the pinion._PWill occur.
[0011]
The inertia coefficient of the steering wheel is J_S, The viscosity coefficient of the steering shaft is D_S, N is the steering wheel rotational angular velocity, and T is the Coulomb friction force of the steering shaft._fThen, pinion torque T_PIs represented by Equation 1.
[0012]
[Expression 1]
T_P= T_S-(J_S* DN / dt + D_S* N) ± T_f
[0013]
In Equation 1, the Coulomb friction force on the right side is expressed as T_fCan be ignored, but the inertia torque (J_S* DN / dt) and viscous torque (D_S* N) cannot be ignored. Especially, the inertia coefficient J of the steering wheel due to the equipment such as the airbag._SCurrently, there is the following problem in the control of the conventional electric power steering device 60.
[0014]
When the steering is suddenly performed, the inertia torque (J) is increased according to the increase of the steering angular acceleration (dN / dt)._S* DN / dt) increases and steering torque T of the steering wheel_SHowever, there is a problem that the handle operation of the driver becomes heavy.
[0015]
In addition, when the steering tries to return to the neutral position due to the reaction force from the road surface, the inertia coefficient J of the steering wheel_SAnd steering shaft viscosity coefficient D_SThe pinion steering force T expressed by the number 2 in the opposite direction to the rotation direction due to the load, etc._PAnd this pinion steering torque T_PIs input, and the electric motor supplies a steering assisting force in the direction opposite to the rotation direction of the steering wheel.
[0016]
[Expression 2]
T_P= J_S* DN / dt + D_S* N
[0017]
The present invention was made to solve such a problem, and its purpose is to generate a steering assist force corresponding to the steering torque intended by the driver by compensating the inertia torque of the steering wheel and the viscous torque of the steering shaft, An object of the present invention is to provide an electric power steering device that improves the steering feeling.
[0018]
[Means for Solving the Problems]
In order to solve the above problems, the steering torque detecting means of the electric power steering apparatus according to the present invention detects a steering torque acting on a steering wheel.
[0019]
Also,The steering torque detecting means of the electric power steering apparatus according to the present invention includes a steering torque sensor disposed in the middle of the steering system, and a steering for calculating a steering torque acting on the steering wheel based on a steering torque signal detected by the steering torque sensor. A torque calculating means is provided.
[0020]
further,The steering torque calculating means of the electric power steering apparatus according to the present invention includes a viscous torque calculating means for calculating a viscous torque based on a steering angular speed signal from a steering angular speed sensor for detecting a steering angular speed of a steering wheel, and a differential value of the steering angular speed signal. An inertia torque calculating means for calculating an inertia torque based on the steering angular acceleration signal is provided.
[0021]
Also,The electric power steering apparatus according to the present invention detects, in the control means, target auxiliary torque setting means for setting a target auxiliary torque signal based on a steering torque signal from the steering torque detection means, and actual auxiliary torque generated by the electric motor. The present invention is characterized by comprising actual auxiliary torque detecting means, and a deviation signal determining means for calculating a deviation signal between the target auxiliary torque signal and the actual auxiliary torque signal from the actual auxiliary torque detecting means.
[0022]
[Action]
Since the steering torque detecting means of the electric power steering device according to the present invention detects the steering torque acting on the steering wheel, it detects the steering torque not including the inertia torque or the viscous torque of the steering system, and based on this steering torque. An auxiliary steering torque can be applied to the steering system by driving the electric motor.
[0023]
Also,Since the steering torque detecting means of the electric power steering apparatus according to the present invention includes a steering torque sensor arranged in the middle of the steering system, and a steering torque calculating means for calculating based on a steering torque signal detected by the steering torque sensor, The steering torque acting on the steering wheel can be detected indirectly.
[0024]
further,The steering torque calculating means of the electric power steering apparatus according to the present invention includes a viscous torque calculating means for calculating a viscous torque based on a steering angular speed signal from a steering angular speed sensor for detecting a steering angular speed of a steering wheel, and a differential value of the steering angular speed signal. Since the inertia torque calculation means for calculating the inertia torque based on the steering angular acceleration signal is provided, the steering torque acting on the steering wheel is corrected by correcting the steering torque detected by the steering torque sensor arranged in the middle of the steering system. Can be estimated.
[0025]
Also,The electric power steering apparatus according to the present invention detects, in the control means, target auxiliary torque setting means for setting a target auxiliary torque signal based on a steering torque signal from the steering torque detection means, and actual auxiliary torque generated by the electric motor. Since the actual auxiliary torque detection means and the deviation signal determining means for calculating the deviation signal of the actual auxiliary torque signal from the target auxiliary torque signal and the actual auxiliary torque detection means are provided, the actual auxiliary torque is quickly converged to the target auxiliary torque. Can be made.
[0026]
【Example】
Embodiments of the present invention will be described below with reference to the accompanying drawings.
Figure 1The present invention1 is an overall configuration diagram of an electric power steering apparatus according to FIG.
In the present invention, a steering torque sensor is arranged on the steering wheel to directly detect the driver's steering torque, and the motor is driven based on this steering torque, thereby energizing the steering system with steering assist force. is there.
[0027]
In FIG. 1, an electric power steering apparatus 1 includes a rack & shaft provided in a steering gear box 4 via a connecting shaft 3 having a universal joint 3 a and 3 b on a steering shaft 2 provided integrally with a steering wheel 17. A manual steering force generating means 6 is configured by being connected to the pinion 5 a of the pinion mechanism 5.
[0028]
The rack shaft 7 is provided with rack teeth 7a meshing with the pinion 5a, and the rack shaft 7 reciprocates by the meshing is connected to left and right front wheels 9 as rolling wheels via tie rods 8 at both ends thereof.
[0029]
In this way, when steering the steering wheel 17, the front wheel 9 is rolled through the usual rack and pinion type steering to change the direction of the vehicle.
[0030]
In order to reduce the steering force generated by the manual steering force generating means 6, an electric motor 10 that supplies a steering assist force is arranged coaxially with the rack shaft 7, via a ball screw mechanism 11 provided substantially parallel to the rack shaft 7. Thus, the steering assist force is converted into thrust and applied to the rack shaft 7.
[0031]
The rotor of the electric motor 10 is integrally provided with a drive-side helical gear 10a, and the drive-side helical gear 10a is connected to a driven-side helical gear 11a provided integrally with the shaft end of the screw shaft of the ball screw mechanism 11. It is engaged.
The nut of the ball screw mechanism 11 is connected to the rack shaft 7.
[0032]
Further, a steering torque sensor 12 for detecting the manual steering torque of the driver is arranged on the steering wheel 17, and an actual auxiliary torque sensor 14 for detecting the actual auxiliary torque acting on the steering system is arranged on the electric motor 10, and detected by the respective torque sensors. Steering torque signal T_S, Actual auxiliary torque signal T_AIs provided to the control means 15.
[0033]
Figure 2The present inventionFIG. 2 shows a configuration diagram of an embodiment of a steering torque sensor provided on the steering wheel of the electric power steering apparatus according to FIG.
In FIG. 2, the steering torque sensor 12 is provided, for example, on a shaft that can rotate integrally with the steering wheel 17, and is composed of a strain gauge whose electric resistance changes in response to the steering torque acting on the steering wheel 17. The current signal corresponding to the steering torque acting on the steering torque signal T_SIs detected and provided to the control means 15.
[0034]
The steering wheel 17 is made of, for example, light metal, and the mounting component 17B such as an airbag is attached to a center pad portion 17A fixed independently of the steering wheel 17 so that the inertia coefficient J of the steering wheel 17 is increased._SAnd steering shaft viscosity coefficient D_SSet to a small value that can be ignored.
[0035]
As described above, since the steering torque sensor 12 is disposed on the steering wheel 17, the inertia coefficient J of the steering wheel 17 is determined._SAnd steering shaft viscosity coefficient D_SIt is possible to detect a steering torque that is not affected by
[0036]
The control means 15 controls the steering torque signal T_SIs converted into a target auxiliary torque signal Ta, and the actual auxiliary torque signal T detected by the actual auxiliary torque sensor 14 is generated by the electric motor 10._ATarget auxiliary torque signal Ta and actual auxiliary torque signal T_ADrive control signal V based on the deviation of_OIs generated.
[0037]
The motor driving means 16 is driven by a drive control signal V provided from the control means 15._OFor example, PWM drive motor voltage V_MThen, the electric motor 10 is driven, the power of the electric motor 10 is applied to the steering system, and the steering force of the driver is reduced.
[0038]
Figure 3The present inventionIt is a principal block block diagram of the electric power steering device concerning.
The electric power steering apparatus 1 includes a control unit 15, a steering torque sensor 12, an actual auxiliary torque sensor 14, an electric motor driving unit 16, and an electric motor 10.
[0039]
The control means 15 is composed of interface means and A / D conversion means based on various arithmetic functions, processing functions and memory of the microprocessor, and includes steering torque conversion means 24A, target auxiliary torque setting means 19 and deviation signal determination means 20. , Drive control means 21 and actual auxiliary torque conversion means 18A constituting actual auxiliary torque detection means 18 are provided.
[0040]
The steering torque detection means 24 includes a steering torque sensor 12 and a steering torque conversion means 24A of the control means 15, and electrically detects the steering torque directly urged by the steering wheel 17 shown in FIG. The detected analog torque steering signal T_SIs converted into a digital value by A / D conversion by the steering torque conversion means 24A._DSIs provided to the target auxiliary torque setting means 19.
[0041]
The target auxiliary torque setting means 19 is composed of a memory such as a ROM, and a steering torque signal T set in advance based on experimental values or design values._DSAnd the target auxiliary torque signal Ta are stored as table data, and the steering torque signal T provided from the steering torque detecting means 24 is stored._DSIs converted into a corresponding target auxiliary torque signal Ta and supplied to the deviation signal determining means 20.
[0042]
The actual auxiliary torque detection means 18 includes an actual auxiliary torque sensor 14 and an actual auxiliary torque conversion means 18A of the control means 15, and the motor torque T of the electric motor 10 detected by the actual auxiliary torque sensor 14 is detected._MThe digital value of the actual auxiliary torque signal T_DMAnd the actual auxiliary torque conversion means 18A outputs the actual auxiliary torque signal T_DMIs converted into a digital value associated with the steering target torque signal Ta, and the actual auxiliary torque signal T_AIs supplied to the deviation signal determination means 20.
[0043]
The deviation signal determination means 20 has a deviation calculation function, and a target auxiliary torque signal Ta from the target auxiliary torque setting means 19 and an actual auxiliary torque signal T from the actual auxiliary torque detection means 18._ADeviation ΔT (= Ta−T_A) And the deviation signal ΔT is supplied to the drive control means 21.
[0044]
The drive control means 21 generates a deviation signal ΔT (= Ta−T_A) Proportional (P), integral (I) and derivative (D) calculation, PID controller for processing, and on to control the direction and magnitude of the generated torque of the motor 10 based on the signal from this PID controller Drive control signal V which is a hybrid signal of signals and PWM (pulse width modulation) signals_OAnd a drive control signal V_OIs supplied to the electric motor driving means 16 and the deviation signal ΔT (= Ta−T_A) Is quickly and stably controlled to 0.
[0045]
When the motor 10 is a DC motor, the motor driving means 16 is constituted by a bridge circuit composed of four FETs (field effect transistors), and a drive control signal V such as an ON signal or PWM (pulse width modulation) signal._OThe drive voltage of the FET (field effect transistor) is controlled by the motor voltage V having the drive direction and magnitude._MTo drive the electric motor 10.
[0046]
The electric motor 10 uses, for example, a DC motor, a brushless motor, or the like, and an electric motor voltage V having a driving direction and a magnitude supplied from the electric motor driving means 16._MDriven by the motor voltage V_MPower corresponding to is generated, and the motor torque acts on the steering system as the steering assist force.
[0047]
FIG. 4 shows a block diagram of an embodiment of the control means in which the target auxiliary torque signal is responsive to the vehicle speed.
In FIG. 4, vehicle speed detection means 22 is added, and control means 15 is provided with correction means 23.
[0048]
The vehicle speed detection means 22 is composed of, for example, a speedometer composed of a rotating disk having a slit and a photocoupler, and a vehicle speed signal V detected by a pulse electric signal having a period proportional to the vehicle speed._DIs supplied to the correction means 23.
[0049]
For example, the correction means 23 is a vehicle speed signal V_DThe steering torque signal T is supplied from the steering torque detecting means 24 and is composed of a variable amplifier having an amplification factor inversely proportional to the increase in_DSVehicle speed signal V_DSteering torque signal T changed according to_DCIs provided to the target auxiliary torque setting means 19, and the target auxiliary torque setting means 19 provides the steering torque signal T._DCA target assist signal Ta corresponding to is generated.
[0050]
Vehicle speed signal V_DTarget assist signal Ta corresponding to the actual assist torque signal T_ADeviation ΔT (= Ta−T_A), The steering operation with a large response can be realized as the vehicle speed changes from a low vehicle speed to a high vehicle speed.
[0051]
in this way,The present inventionThe electric power steering apparatus 1 according to the invention detects a steering torque directly urged to the steering wheel, and corresponds to a target auxiliary torque signal Ta corresponding to the steering torque and a motor torque generated by the electric motor, and a target auxiliary torque signal. Actual auxiliary torque T associated with Ta_ADeviation ΔT (= Ta−T_A) Is driven based on the steering torque that does not include the inertia torque or the viscous torque of the steering system, and the steering assist force can be supplied to the steering system.
[0052]
FIG.The present inventionPertaining toanotherIt is a whole lineblock diagram of an electric power steering device.
In FIG. 5, the electric power steering apparatus 30 has the steering torque sensor 12 and the steering angular velocity sensor 13 provided in the steering gear box 4 and the control means 31 provided in the electric power steering apparatus 1 shown in FIG. And different.
In the present invention, a steering torque sensor is arranged in the steering gear box to indirectly detect the driver's steering torque as a pinion steering torque, and the steering torque acting on the steering wheel is calculated based on the pinion steering torque. Then, the electric motor is driven based on the calculated steering torque, and the steering assist force is urged to the steering system.
[0053]
The control means 31 calculates the inertia torque and the viscous torque of the steering wheel 17 based on the steering angular velocity signal N detected by the steering angular velocity sensor 13, and the pinion steering torque T detected by the steering torque sensor 12 based on the equation (1)._PThe steering torque T acting directly on the steering wheel 17 by adding the calculated inertia torque and viscous torque to_SIs configured to calculate
[0054]
FIG.The present inventionIt is a principal block block diagram of the control means concerning.
In FIG. 6, the control means 31 includes a steering torque conversion means 24A, a steering angular speed conversion means 32A constituting a part of the steering angular speed detection means 32, a steering torque calculation means 33, a target auxiliary torque setting means 19, and a deviation signal determination means 20. Drive control means 21 is provided.
[0055]
The steering torque conversion means 24A is an analog signal pinion steering torque signal T that electrically detects the pinion steering torque in the steering gear box 4 detected by the steering torque sensor 12._PA / D conversion of the pinion steering torque signal T converted to a digital value_DPIs provided to the steering torque calculation means 33.
[0056]
The steering angular velocity converting means 32A performs A / D conversion on the analog steering angular velocity signal N detected electrically by the steering angular velocity of the steering shaft 2 detected by the steering angular velocity sensor 13, and converted into a digital value._DIs provided to the steering torque calculation means 33.
[0057]
The steering torque calculating means 33 includes an inertia torque calculating means 34, a viscous torque calculating means 35, and an adding means 36.
The inertia torque calculation means 34 is a steering angular speed signal N provided from the steering angular speed conversion means 32A._DTo the steering angular acceleration signal (dN_D/ Dt) and a differential operation means for outputting the inertia torque T_JTo calculate the inertia torque signal T_JIs supplied to the adding means 36.
[0058]
The viscous torque calculation means 35 is a steering angular speed signal N provided from the steering angular speed conversion means 32A._DBased on the viscous torque T_DTo calculate the viscous torque signal T_DIs supplied to the adding means 36.
The adding means 36 is an inertia torque signal T_J, Viscous torque signal T_DAnd pinion steering torque signal T_DPAnd the steering torque T acting directly on the steering wheel 17 shown in Equation 1_SThe digital steering torque T corresponding to_SOIs provided to the target auxiliary torque setting means 19.
[0059]
Since the target auxiliary torque setting means 19, the deviation signal determining means 20, and the drive control means 21 have the same configuration and function as those shown in the control means 15 of FIG.
[0060]
In FIG.Book1 is a block diagram of a main part of one embodiment of a steering torque calculating means according to the invention.
In FIG. 7, the steering torque calculating means 33 includes an inertia torque calculating means 34, a viscous torque calculating means 35, and an adding means 36.
[0061]
The inertia torque calculation unit 34 includes an inertia coefficient storage unit 41, a differential calculation unit 42, and a multiplication unit 43.
The inertia coefficient storage means 41 is composed of a memory such as a ROM, and the inertia coefficient J of the steering wheel 17 determined in advance from design values and experimental values._SData for the inertia coefficient signal J_SIs supplied to the multiplication means 43.
[0062]
The differential calculation means 42 has a differential calculation function, and a steering angular velocity signal N_DTo calculate the steering angular acceleration (dN_D/ Dt), the steering angular acceleration signal (dN_D/ Dt) is supplied to the multiplication means 43.
The multiplying means 43 receives the inertia coefficient signal J_SAnd steering angular acceleration signal (dN_D/ Dt) and the inertia torque signal T_J(= J_S* DN_D/ Dt) is supplied to the adding means 36.
[0063]
The viscosity torque calculation means 35 includes a viscosity coefficient storage means 44 and a multiplication means 45.
The viscosity coefficient storage means 44 is constituted by a memory such as a ROM, and the viscosity coefficient D of the steering shaft 2 determined in advance from design values and experimental values._SIs set, viscosity coefficient signal D_SIs supplied to the multiplication means 45.
The multiplication means 45 is adapted to output the viscosity coefficient signal D_SAnd steering angular velocity signal N_DAnd the viscous torque signal T_D(= D_S* N_D) Is supplied to the adding means 36.
[0064]
The adding means 36 is an inertia torque signal T_J(= J_S* DN_D/ Dt), viscous torque signal T_D(= D_S* N_D) And pinion steering torque signal T_DPAnd the steering torque T acting directly on the steering wheel 17_SThe digital steering torque signal T corresponding to_SOIs provided to the target auxiliary torque setting means 19.
[0065]
As described above, the electric power steering apparatus 30 includes the control means 31 including the inertia torque calculating means 34 and the viscous torque calculating means 35, and the pinion steering torque signal T_DP, Inertia torque signal T_JAnd viscous torque signal T_DAnd the steering torque signal T acting directly on the steering wheel 17_SOIs calculated, the steering torque acting on the steering wheel can be estimated, and the steering torque signal T_SOThe target auxiliary torque signal Ta is set based on the target auxiliary torque signal Ta and the actual auxiliary torque signal T._ABased on the deviation, the electric motor can be driven to quickly converge the actual auxiliary torque to the target auxiliary torque.
[0066]
Figure 8BookThe block diagram of the main part of another embodiment of the steering torque calculating means according to the invention is shown.
In FIG. 8, the steering torque calculating means 50 includes a differential calculating means 52, a differential calculating means 53, and an inertia coefficient J of the steering wheel._S54, the steering shaft viscosity coefficient D_SIs provided.
[0067]
The differential calculation means 52 detects the steering angle of the steering wheel 17 with an analog electric signal and converts it to a digital value._D1Is the differential operation (dθ_D1/ Dt) and rotational angular velocity N_DTo calculate the angular velocity signal N_DIs supplied to the differential operation means 53 and the multiplier 55.
[0068]
The differential calculation means 53 is a rotational angular velocity signal N supplied from the differential calculation means 52._DTo calculate the steering angular acceleration (dN_D/ Dt), the steering angular acceleration signal (dN_D/ Dt) to the multiplier 54.
[0069]
The multiplier 54 generates a steering angular acceleration signal (dN_D/ Dt) to inertia coefficient J_SMultiplied by the inertia torque T_J(= J_S* DN_D/ Dt), and the inertia torque signal T_JIs provided to the adding means 36.
[0070]
The multiplier 55 receives the rotation angular velocity signal N supplied from the differential calculation means 52._DViscosity coefficient D_SMultiplied by the viscous torque T_D(= D_S* N_D) To calculate the viscous torque signal T_DIs provided to the adding means 36.
[0071]
The adding means 36 is a pinion steering torque signal T from the steering torque detecting means 24._DP, Inertia torque signal T from multiplier 54_JAnd a multiplier 55, and a digital steering torque signal T is added._SOIs provided to the target auxiliary torque setting means 19.
[0072]
When the rack shaft 7 has a displacement detection means such as a stroke sensor, the steering torque signal T_SOCan be calculated.
Pinion steering torque signal T_DPIs the spring stiffness coefficient of the pinion steering torque detection means k₁, The equivalent displacement angle (digital conversion value) of the rack shaft is θ_D2Then, it is expressed by Equation 3.
[0073]
[Equation 3]
T_DP= K₁* (Θ_D1−θ_D2)
Where θ_D1Is the steering angle signal
[0074]
From Equation 3, steering angle signal θ_D1Is calculated, and this steering angle signal θ_D1The steering angle signal θ from the steering angle detection means 51 shown in FIG._D1Instead of providing the differential operation means 52 with the steering torque signal T as a digital value._SOCan be calculated.
[0075]
In FIG.BookThe block diagram of the main part of another embodiment of the steering torque calculating means according to the invention is shown.
In FIG. 9, the steering torque calculation means 56 is a spring stiffness coefficient k of the pinion steering torque detection means.₁Reciprocal signal (1 / k₁) And an equivalent displacement angle (digital conversion value) θ from a rack shaft displacement detecting means 57 provided in place of the steering angle detecting means 51 shown in FIG._D28 is different from the steering torque calculation means 50 of FIG. 8 in that an adder 59 is provided.
[0076]
The multiplier 58 generates a pinion steering torque signal T from the steering torque detector 24._DPAnd spring stiffness coefficient k₁Reciprocal signal (1 / k₁) And the steering angle deviation signal (θ_D1−θ_D2) Is supplied to the adder 59.
[0077]
The adder 59 is a steering angle deviation signal (θ_D1−θ_D2) And the equivalent displacement angle (digital conversion value) θ from the rack shaft displacement detecting means 57_D2And the steering angle signal θ_D1Is provided to the differential calculation means 52, thereby providing a digital value of the steering torque signal T._SOIs calculated and provided to the target auxiliary torque setting means 19.
[0078]
Note that the control means 31 is provided with the correction means 23 shown in FIG._DBased on the steering torque signal T_DSIt can also be configured to change the vehicle speed and respond to the vehicle speed.
[0079]
In the above embodiment, the inertia torque T_JAnd viscous torque T_DWas corrected, but the inertia torque T_JAnd viscous torque T_DOnly one of these may be corrected.
Also, Coulomb friction force T_fMinutes may be corrected.
[0080]
【The invention's effect】
The steering torque detecting means of the electric power steering apparatus according to the present invention includes a steering torque sensor disposed on the steering wheel, and can directly detect the steering torque acting on the steering wheel. Thus, the steering assist force corresponding to the steering torque intended by the driver can be generated.
[0081]
Further, the steering torque detecting means of the electric power steering apparatus according to the present invention includes a steering torque sensor arranged in the middle of the steering system, and a steering torque calculating means for calculating based on a steering torque signal detected by the steering torque sensor, Since the steering torque acting on the steering wheel can be indirectly detected, the steering assist force corresponding to the steering torque intended by the driver can be generated by compensating the inertia torque of the steering wheel and the viscosity torque of the steering shaft. it can.
[0082]
Furthermore, the electric power steering apparatus according to the present invention includes a control means that includes target auxiliary torque setting means for setting a target auxiliary torque signal based on a steering torque signal from the steering torque detection means, and actual auxiliary torque generated by the electric motor. A real auxiliary torque detecting means for detecting, and a deviation signal determining means for calculating a deviation signal between the target auxiliary torque signal and the real auxiliary torque signal from the real auxiliary torque detecting means, and the real auxiliary torque is quickly converged to the target auxiliary torque. And a stable steering feeling can be obtained.
[0083]
Accordingly, it is possible to provide an electric power steering apparatus with good steering feeling by compensating for the inertia torque of the steering wheel and the viscous torque of the steering shaft to generate the steering assist force corresponding to the steering torque intended by the driver.
[Brief description of the drawings]
[Figure 1]The present inventionOverall configuration diagram of an electric power steering device according to the present invention
[Figure 2]The present inventionFIG. 1 is a block diagram of an embodiment of a steering torque sensor provided on a steering wheel of an electric power steering apparatus according to the present invention.
[Fig. 3]The present inventionThe principal block block diagram of the electric power steering device which concerns on
FIG. 4 is a block diagram of an embodiment of control means in which a target auxiliary torque signal is responsive to vehicle speed.
[Figure 5]The present inventionPertaining toanotherOverall configuration diagram of electric power steering system
[Fig. 6]The present inventionBlock diagram of the main part of the control means according to
[Fig. 7]BookFIG. 1 is a block diagram of a main part of an embodiment of a steering torque calculating means according to the invention.
[Fig. 8]BookBlock diagram of main part of another embodiment of steering torque calculating means according to the invention
FIG. 9BookBlock diagram of main part of another embodiment of steering torque calculating means according to the invention
FIG. 10 is a block diagram of a main part of a conventional electric power steering apparatus.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1,30 ... Electric power steering device, 2 ... Steering shaft, 3a, 3b ... Universal joint, 3 ... Connecting shaft, 4 ... Steering gear box, 5 ... Rack & pinion mechanism, 5a ... Pinion, 6 ... Manual steering force generation Means: 7 ... Rack shaft, 7a ... Rack teeth, 8 ... Tie rod, 9 ... Front wheel, 10 ... Electric motor, 10a ... Drive side helical gear, 11 ... Ball screw mechanism, 11a ... Drive side helical gear, 12 ... Steering torque Sensor: 13 ... Steering angular velocity sensor, 14 ... Actual auxiliary torque sensor, 15, 31 ... Control means, 16 ... Electric motor drive means, 17 ... Steering wheel, 17A ... Center pad portion, 17B ... Mounted parts such as airbag, 18 ... Actual Auxiliary torque detection means, 18A ... actual auxiliary torque conversion means, 19 ... target auxiliary torque setting means, 20 ... deviation signal determination means, 21 ... drive Control means 22 ... Vehicle speed detection means 23 ... Correction means 24 ... Steering torque detection means 24A ... Steering torque conversion means 32 ... Steering angular speed detection means 32A ... Steering angular speed conversion means 33, 50, 56 ... Steering Torque calculation means 34 ... Inertia torque calculation means 35 ... Viscosity torque calculation means 36 ... Addition means 41 ... Inertia coefficient storage means 42 ... Differential calculation means 43,45 ... Multiplication means 44 ... Viscosity coefficient storage means 51: Steering angle detection means, 52, 53 ... Differential calculation means, 54, 55, 58 ... Multiplier, 59 ... Adder, D_S... viscosity coefficient, dN / dt ... steering angular acceleration signal, J_S... Inertia coefficient, k₁... Spring stiffness coefficient, N, N_D... Rotational angular velocity signal, Ta ... Target assist signal, T_A, T_DM... Actual auxiliary torque signal, T_D... Viscous torque signal, T_DC, T_DS, T_SO... Steering torque signal, T_DP, T_P... Pinion steering torque signal, T_J... Inertia torque signal, T_M... Motor torque, T_S... steering torque, ΔT (= Ta-T_A) ... Deviation signal, V_D... Vehicle speed signal, V_M... Motor voltage, V_O... Drive control signal, θ_D1... Steering angle signal, θ_D2... Equivalent displacement angle of rack shaft (digital conversion value).

Claims (2)

Steering torque detecting means for detecting steering torque of the steering system, control means for generating an electric motor control signal based on the steering torque signal of the steering torque detecting means, and electric motor driving means for driving the electric motor based on the electric motor control signal And an electric power steering apparatus including the electric motor driven by an electric motor driving signal from the electric motor driving means and acting on a steering system with a steering assist force.
The steering torque detecting means includes a steering torque sensor arranged in the middle of the steering system, and a steering torque calculating means for calculating a steering torque acting on the steering wheel based on a steering torque signal detected by the steering torque sensor,
The steering torque calculating means includes a viscous torque calculating means for calculating a viscous torque based on a steering angular speed signal from a steering angular speed sensor that detects a steering angular speed of the steering wheel, and a steering angular acceleration signal that is a differential value of the steering angular speed signal. An electric power steering device comprising an inertia torque calculating means for calculating an inertia torque based on the inertia torque . Target auxiliary torque setting means for setting a target auxiliary torque signal on the control means based on the steering torque signal from the steering torque detection means; and real auxiliary torque detection means for detecting actual auxiliary torque generated by the electric motor; 2. The electric power steering apparatus according to claim 1, further comprising deviation signal determining means for calculating a deviation signal between the target auxiliary torque signal and the actual auxiliary torque signal from the actual auxiliary torque detecting means .

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