KR100567516B1 - Device for controlling electric power steering - Google Patents

Abstract

assignment

In the conventional electric power steering control apparatus, since the technique of determining the time constant of the low pass filter of the road reaction force torque detector according to the values of both the steering speed and the vehicle speed has not been proposed, there is a problem in the road reaction torque estimation accuracy. .

Resolution

Road reaction force torque detectors 15, 15A to 15F having a vehicle speed detected by the vehicle speed detector 11 and a low pass filter element 151 whose time constant is determined in response to the motor speed detected by the motor speed detector 13. The road surface reaction torque torque estimate was obtained by performing a low pass filter on the steering shaft reaction force torque signal outputted by the steering shaft reaction force torque signal output means, to increase the accuracy of the road surface reaction torque estimation.

Power steering, road surface reaction torque

Description

Electric power steering control device {DEVICE FOR CONTROLLING ELECTRIC POWER STEERING}

1 is a block diagram showing an electric power steering control apparatus according to a first embodiment of the present invention.

2 is a principle diagram of a road surface reaction torque estimation calculation of the electric power steering control apparatus according to the first embodiment of the present invention.

3 is a characteristic diagram showing road reaction force torque and friction torque of the electric power steering control apparatus according to the first embodiment of the present invention.

4 is a block diagram showing the electric power steering control apparatus according to the first embodiment of the present invention.

Fig. 5 is a block diagram showing a road surface reaction torque detector of the electric power steering control device according to the first embodiment of the present invention.

6 is a flowchart showing the operation of the road surface reaction torque detector of the electric power steering control apparatus according to the first embodiment of the present invention.

Fig. 7 is a characteristic diagram showing the relationship between vehicle speed and alignment torque / steering angle of the electric power steering control apparatus according to the first embodiment of the present invention.

8 is a block diagram showing a configuration of a motor speed calculating section of the electric power steering control apparatus according to the first embodiment of the present invention.

9 is a block diagram showing an electric power steering control apparatus according to a second embodiment of the present invention.

10 is a block diagram showing a road surface reaction torque detector of the electric power steering control apparatus according to the second embodiment of the present invention.

Fig. 11 is a flowchart showing the operation of the road surface reaction torque detector of the electric power steering control device according to the second embodiment of the present invention.

12 is a characteristic diagram showing the relationship between the road reaction force torque and the steering angle of the electric power steering control apparatus according to the third embodiment of the present invention.

Fig. 13 is a block diagram showing a road surface reaction torque detector of an electric power steering control device according to a third embodiment of the present invention.

Fig. 14 is a flowchart showing the operation of the road surface reaction torque detector of the electric power steering control apparatus according to the third embodiment of the present invention.

Fig. 15 is a block diagram showing another road surface reaction torque detector used in the electric power steering control apparatus according to the third embodiment of the present invention.

16 is a block diagram showing a road surface reaction torque detector of the electric power steering control apparatus according to the fourth embodiment of the present invention.

Fig. 17 is a flowchart showing the operation of the road surface reaction torque detector of the electric power steering control apparatus according to the fourth embodiment of the present invention.

18 is a block diagram showing a road surface reaction torque detector of the electric power steering control apparatus according to the fifth embodiment of the present invention.

19A is a block diagram showing a road surface reaction torque detector of the electric power steering control apparatus according to the sixth embodiment of the present invention.

19B is a characteristic diagram showing a relationship between a steering speed and a vehicle speed in the electric power steering control device according to the sixth embodiment of the present invention.

20 is a block diagram showing an electric power steering control device according to a seventh embodiment of the present invention.

21 is a block diagram showing an electric power steering control device according to an eighth embodiment of the present invention.

♠ Explanation of the symbols for the main parts of the drawings.

4: motor 11: vehicle speed detector

12: steering torque detector 13: motor speed detector

14 motor acceleration detector 15 road surface reaction torque detector

16: assist torque determination block 17: motor current determiner

18: motor driver 20: motor current detector

Technical Field

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electric power steering control apparatus for controlling an electric motor that generates an earth torque that assists steering torque by a driver of an automobile.

Conventional technology

In the conventional electric power steering control device, in order to estimate the road surface reaction torque, it is necessary to construct one or more first-order low pass filters, and to change the time constant of the low pass filters in response to the steering speed. Japanese Patent Application Laid-Open No. 2001-239951 discloses a modification of the time constant of a low pass filter in response to a vehicle speed.

However, as in the conventional technique, determining the time constant of the low pass filter in response to the steering speed only has a problem in that the estimation accuracy of the road reaction reaction torque decreases when the vehicle speed increases, and the low pass filter in response to the vehicle speed only has a problem. Determining the time constant has a problem that the estimation accuracy of the road reaction force torque is lowered when the steering speed is increased. Until now, the technique which determines the time constant of a lowpass filter according to both the rotational speed of an electric motor which produces a steering speed or an assist torque, and a vehicle speed is not proposed.

SUMMARY OF THE INVENTION The present invention has been made to solve the above problems, and the time constant of the low pass filter is configured to be determined by using both the rotational speed and the vehicle speed of the electric motor generating assist torque. An object of the present invention is to obtain an electric power steering control device capable of improving the estimation accuracy.

The electric power steering control apparatus which concerns on this invention WHEREIN: The electric power steering control apparatus which has an electric motor which provides the assist torque which assists a driver's steering torque to the steering shaft connected to an axle, The vehicle speed detection means which detects a vehicle speed, The said A low speed motor speed detecting means for detecting a rotational speed of an electric motor, a steering shaft reaction torque signal output means for outputting a steering reaction torque signal in response to a steering shaft reaction torque with respect to the steering shaft, and the steering shaft reaction torque signal A road surface reaction torque detection means for obtaining a road surface reaction force torque estimate value used for controlling the assist torque by filtering by a filter operation, the vehicle speed detected by the vehicle speed detection means and the motor detected by the motor speed detection means The lowpass filter in response to speed It will have to determine the time constant of the low.

According to the electric power steering control apparatus which concerns on this invention, even when the rotation speed of the electric motor which gives an assist torque changes, or when the vehicle speed changes, estimation of road reaction force torque becomes possible, and it responds to them. Electric power steering control can be realized.

Embodiment of embodiment

First embodiment

1 is a schematic diagram showing an electric power steering control apparatus according to a first embodiment of the present invention.

In Fig. 1, reference numeral 1 denotes a steering wheel of a vehicle to be steered by the driver of the vehicle, and is coupled to the steering shaft 1A. 2 is a tire attached to both ends of the axle 2A of the vehicle, and the steering shaft 1A is connected to steer it to the axle 2A. 3 is a torque sensor provided in the steering shaft 1A among steering torque transmission mechanisms from the steering wheel 1 to the tire 2, for example, and detects steering torque by the steering wheel operation of the driver. 4 is an EPS (Electric Power Steering) motor coupled to give assist torque to the steering shaft 1A among the steering torque transmission mechanisms from the handle 1 to the tire 2, and assists the steering torque by the driver. To generate assist torque. 5 is an electronic control unit for controlling the EPS motor 4 (hereinafter referred to as EPS-ECU), 6 is a steering angle sensor provided to detect a steering angle of the steering wheel 1 by a driver, The steering angle from the neutral position of the handle 1 is detected. 7 is a reduction gear provided between the EPS motor 4 and the steering shaft 1A, and the EPS motor 4 decelerally drives the steering shaft 1A through this reduction gear 7.

The reference sign θ hdl is the steering angle of the steering wheel 1, θ sens is the steering angle detection signal output from the steering angle sensor 6, Tsens is the steering torque detection signal output from the torque sensor 3, and Imtr_sens is the EPS motor 4. Drive current detection signal, Vt_sens is the drive voltage detection signal of the EPS motor 4, Vsupply is the power supply voltage for the EPS motor 4, Tassist is the assist given to the steering shaft 1A by the EPS motor 4 Torque, Thdl is the steering torque given to the steering wheel 1 by the driver, Ttran is the steering shaft reaction torque given from the tire 2 to the steering shaft 1A, Tfrp is the steering from the steering shaft 1A to the axle 2A The friction torque, Talign, in the path is the road reaction force torque given from the tire 2.

2 is a principle diagram of a road reaction force torque estimation calculation of the electric power steering control apparatus according to the first embodiment of the present invention, and includes a low pass filter element 151. The low pass filter element 151 performs the same signal processing as the input signal is filtered by the low pass filter by the microprocessor in the ECU 5 for EPS, and it is necessary to actually use the low pass filter as hardware. There is no.

In Fig. 2, Ttire_est is a road reaction force torque estimate,? Est is a time constant of the low pass filter element 151, and s is a Laplace transform variable. The calculation block 151 receives the steering shaft reaction force torque signal Ttran_sens corresponding to the steering shaft reaction force torque Ttran, multiplies it by 1 / τest × s + 1, and outputs the road surface reaction torque torque estimate Ttire_est. .

3 is a characteristic diagram showing changes in torque and time of the electric power steering control apparatus according to the first embodiment of the present invention.

In FIG. 3, the vertical axis is torque Nm, and the horizontal axis is time (second). The characteristic A represents a change in the steering shaft reaction force torque Ttran, the characteristic B represents a change in the road surface reaction torque estimate Ttire_est, and the characteristic C represents a change in the friction torque Tfrp. Property A is the sum of property B and property C.

FIG. 4 is a block diagram showing the electric power steering control device according to the first embodiment of the present invention, wherein the portion 10 enclosed by a dashed line in the drawing shows a target value for the drive current Imtr of the motor 4. Is a calculation block 10 for computing.

In Fig. 4, reference numeral 11 denotes a vehicle speed detector which detects a vehicle speed Sveh of the vehicle and generates a vehicle speed signal Sveh_sens, and is a vehicle speed detecting means. 12 is a steering torque detector which detects the steering torque Thdl with respect to the handle 1 as a steering torque detection signal Tsens, and is a steering torque detection means. 13 is a motor speed detector for detecting the rotation speed Smtr of the EPS motor 4 as the rotation speed detection signal Smtr_sens, and is a motor speed detection means. 14 is a motor acceleration detector which detects the rotational acceleration signal (including acceleration) Amtr_sens of the motor 4 based on the output of the motor speed detector 13, and is a motor acceleration detection means. 15 is a road surface reaction force torque detector, and a road surface reaction force torque detection means. This road surface reaction force torque detector 15 receives a steering shaft reaction force torque Ttran, and receives a vehicle speed signal Sveh_sens from the vehicle speed detector 11 and a motor rotational speed detection signal Smtr_sens from the motor speed detector 13. The road surface reaction torque estimate Ttire_est is output using the output of?. 16 is an assist torque determination block, the vehicle speed signal Sveh_sens from the vehicle speed detector 11, the steering torque detection signal Tsens from the steering torque detector 12, and the motor speed detection signal from the motor speed detector 13 ( Based on the output of the motor acceleration detection signal Amtr_sens from Smtr_sens and the motor acceleration detector 14, an assist torque Tassist to assist the steering torque Thdl is determined. 17 is a motor current determiner for determining a target value for the drive current Imtr of the EPS motor 4 based on the output of the assist torque determination block 16, 18 is a motor driver for driving the EPS motor 4, 20 is The motor current detector detects the drive current Imtr of the EPS motor 4 and outputs a motor current detection signal Imtr_sens. The motor driver 18 uses an EPS motor (so that the target value for the drive current Imtr from the motor current determiner 17 and the motor current detection signal Imtr_sens detected by the motor current detector 20 are equal to each other). 4), the EPS motor 4 generates an assist torque.

FIG. 5 is a functional block diagram showing a concrete configuration of the road reaction force torque detector 15 of the electric power steering control device according to the first embodiment of the present invention, and the portion surrounded by the dashed line is a road reaction force torque detector 15 Corresponds to).

In Fig. 5, reference numeral 21 denotes a detection block of the steering shaft reaction force torque Ttran, receives the steering shaft reaction force torque Ttran, and outputs a steering shaft reaction force torque signal Ttran_sens proportional thereto. 22 is an arithmetic block of Kalign, and the ratio of the road reaction force torque (alignment torque) (Talign) and the steering angle (θhdl) is based on the vehicle speed signal Sveh_sens from the vehicle speed detector 11. ) Is calculated. 23 is a time constant calculation block, and calculates the time constant of the low pass filter element 151 based on the ratio Kalign from the calculation block 22 and the motor speed signal Smtr_sens from the motor speed detector 13. . 24 is a low-pass filter calculation block that calculates and outputs the road surface reaction torque torque estimate Ttire_est based on the steering shaft reaction force torque signal Ttran_sens and the output of the time constant calculation block 23 from the detection block 21. .

FIG. 6 is a flowchart showing the operation of the road surface reaction torque detector 15 of the electric power steering control apparatus according to the first embodiment of the present invention. This flowchart includes seven processing steps (S101 to S107) between the start and the end. This step (S101 to S107) will be described later.

FIG. 7 shows the characteristics of vehicle speed Sveh and Kalign, that is, road reaction force torque (alignment torque) (Talign) / steering angle (θhdl) of the motor vehicle of the electric power steering control apparatus according to the first embodiment of the present invention. It is a characteristic diagram which shows D.

In Fig. 7, the horizontal axis represents the vehicle speed and the vertical axis represents the ratio Kalign, that is, the ratio with respect to the steering angle? Hdl of the road reaction force torque (alignment torque) Talign. As apparent from the characteristic D, when the vehicle speed Sveh is small, the ratio Kalign of the road surface reaction force torque (alignment torque) Talign to the steering angle θhd1 is small, and as the vehicle speed Sveh increases, Kalign becomes large.

Next, the operation of the first embodiment will be described.

The electric power steering control device measures the steering torque Thdl when the driver is bending the steering wheel 1 as the steering torque detection signal Tsens by the torque sensor 3, and responds to the steering torque detection signal Tsens. The main function is to generate assist torque (Tassist) to assist the steering torque (Thdl). In addition, in order to realize better steering peeling and steering stability, the steering angle θhdl of the steering wheel 1, the rotational speed of the EPS motor 4, or the rotational angular velocity (differentially obtain the motor angular acceleration) may be obtained. Have a sensor to measure. The EPS-ECU 5 also controls the detection signal Imtr_sens of the drive current Imtr of the EPS motor 4 and the detection signal Vt_sens of the drive voltage Vt applied between the terminals of the motor 4. Is accepted.

Dynamically, the sum of the steering torque Thdl and the assist torque Tassist rotates the steering shaft 1A against the steering shaft reaction force torque Ttran. In addition, when the steering wheel 1 is rotated, since the inertia term (J is the inertia gain of the motor 4) of the motor 4 also acts, the relationship of the following formula 1 holds.

The assist torque Tassist by the motor 4 is given by following formula (2).

Here, Ggear is a reduction gear ratio of the reduction gear 7 of the electric power steering control apparatus, and Kt is a torque constant.

The steering shaft reaction force torque Ttran is the sum of the road surface reaction force torque Talign and the total friction torque Tfric_all in the steering mechanism, and is given by the following expression (3).

In the EPS_ECU 5 which is a control device of the electric power steering control device, a target value for the drive current Imtr of the EPS motor 4 is calculated from the sensor signal described above, and the actual drive of the EPS motor 4 is performed. Current control is made so that the current Iact coincides, and the EPS motor 4 generates a predetermined torque obtained by multiplying the drive current value by the torque constant and the gear ratio (between the motor and the steering shaft), and the steering torque when the driver steers. Is configured to assist.

Next, a road surface reaction torque estimation method will be described.

Since the conventional road surface reaction torque detector in the electric power steering control device is constructed assuming lane change steering at medium and low speeds, the condition under which the road surface reaction torque estimation can be accurately estimated is low to medium speed. Limited to low-frequency steering at. According to the present invention, the road reaction force torque estimate is mechanically connected to the road surface reaction torque estimate by expanding an operating range capable of accurately obtaining road reaction force torque estimates under a wider operating condition and further accurately performing road reaction force torque estimation. It aims at making it possible to use also as a target value of a steering torque generation apparatus in the steer-by-wire apparatus which is not performed.

The road surface reaction torque detector 15 performs estimation based on the principle diagram of the calculation of the road surface reaction force torque shown in FIG. In the electric power steering control device, since the steering shaft rotational speed cannot be detected with high accuracy, it is difficult to directly remove the influence of the friction term. Therefore, estimation has been performed using a filter.

The road reaction force torque estimate Ttire_est is estimated by inputting the steering shaft reaction force torque signal Ttran_sens to the low pass filter element 151, as shown in FIG.

First, steering is performed in various scenes such as curves and lane changes, but the steering pattern is regarded as a ramp state at a constant speed within a predetermined time range. The road surface reaction torque in that case is the same as the characteristic B of FIG. 3, and the friction torque in that case is represented by the characteristic C of FIG. 3, and the steering shaft reaction torque Ttran which is their sum is the characteristic A of FIG. Will appear. In addition, when this is expressed by an equation, the road reaction force torque Talign and the steering shaft reaction force torque Ttran are as shown in Equations 4 and 5, respectively. Where s is the Laplace transform variable.

Here, Tgrad is the rate of change of the road reaction torque Talign, Ggear is the reduction gear ratio of the reduction gear 7 of the electric power steering apparatus, Tfric is the normal friction torque of the EPS motor 4, and Tfrp is the friction torque in the steering mechanism. .

The road surface reaction torque torque estimate Ttire_est obtained by filtering the steering shaft reaction force torque signal Ttran_sens corresponding to the steering shaft reaction force torque Ttran by the low pass filter element 151 is obtained by the following expression (6).

At this time, the estimation error E (s) of the road reaction force torque Talign and the road reaction force torque estimated value Ttire_est, which are the state quantities to be estimated, is expressed by the following equation.

Therefore, when the time constant? Est of the low pass filter 151 is represented by Equation 8 below, the estimation error E (s) becomes 0 (see FIG. 3).

Here, the time change rate Tgrad of the road reaction force torque Talign is expressed as the product of the ratio Kalign to the steering angle of the road reaction force torque Talign and the steering speed ωs as shown in Equation 9 below. .

Among them, the ratio Kalign with respect to the steering angle of the road reaction force torque Talign is determined for each vehicle speed when the vehicle model is determined as shown in FIG. 7. In addition, the steering speed omega s can be detected. Therefore, the optimum value of the time constant? Est of the low pass filter element 151 is determined by Equation 10 below.

Then, as shown in the block diagram of FIG. 5, the time constant τest of the low pass filter element 151 is varied using blocks 22, 23, and 24, thereby rotating the EPS motor 4. Even if the steering speed ωs changes due to the change in the speed Smtr and the vehicle speed Sveh changes, the road surface reaction force torque Ttire_sens can be estimated.

4 and 5 show the configuration according to the first embodiment.

In the first embodiment, the control amount of the electric power steering is determined by the vehicle speed signal Sveh_sens by the vehicle speed detector 11, the steering torque detection signal Tsens by the steering torque detector 12, and the road surface reaction torque. The road reaction force torque estimation value Ttire_est by the detector 15, the motor speed detection signal Smtr_sens by the motor speed detector 13, and the motor acceleration signal Amtr_sens by the motor acceleration detector 14 are provided. Here, since the novel element in this invention relates to road surface reaction force torque detection, the road surface reaction force torque detector 15 is explained in full detail below.

In the first embodiment, the road surface reaction torque detector 15 has a steering shaft reaction force torque Ttran for detecting the steering shaft reaction force torque signal Ttran_sens, as shown in FIG. 5. The vehicle speed signal Sveh_sens is given to a block 22 that calculates the Kalign to the steering angle of the road reaction force torque, and the motor speed detection signal Smtr_sens is also provided to the low pass filter element 151. It is input to the block 23 which calculates time constant (tau).

The steering shaft reaction torque signal Ttran_sens is capable of measuring the amount of state by attaching a detector (steering shaft reaction torque detection means) such as a load cell to the steering shaft column, and the torque generated on the steering shaft column (steering shaft). Reaction force torque).

In addition, the motor speed detection signal Smtr_sens is detected using the output of the motor speed detector 13. However, using the output of the motor current, it is also possible to obtain the motor speed according to the following expression (11).

In the first embodiment and the following embodiments, the motor speed detector 13 can detect the motor speed either by measurement or by calculation.

For example, FIG. 8 detects a motor speed by calculation.

Fig. 8 is a block showing the configuration of an arithmetic unit in the case of calculating the speed of the motor 4 in the motor speed detector 13 of the electric power steering control device according to the first embodiment of the present invention. It is also.

In Fig. 8, reference numeral 161 denotes a calculation block indicating the EPS motor 4, and the coil resistance R of the EPS motor 4 and the product LS of the inductance L and the Laplace transform variable S are shown. The sum is included in the denominator. In this block 161, the difference (Vt-Ve) between the drive voltage Vt of the EPS motor 4 and the counter electromotive voltage Ve of the EPS motor 4 is input. 162 is an arithmetic block that receives the actual drive current Iact of the EPS motor 4 from the arithmetic block 161, multiplies it by a torque constant Kt, and generates a torque output. Gain calculation blocks 164A and 164B are integrators that receive the difference between the torque output and the disturbance torque Tdist, and the integrator 164A integrates the output of the gain calculation block 163 and the counter electromotive voltage constant Kb. ) Is given to arithmetic block 165. The operation block 165 generates the counter electromotive force Ve. In the calculation shown in FIG. 8, the driving voltage Vt of the EPS motor 4, the counter electromotive voltage Ve of the EPS motor 4 from the calculating unit 165, and the coil resistance of the EPS motor 4 ( Using R) and the coil inductance L, the rotational speed? Of the EPS motor 4 can be calculated by the following equation (11).

FIG. 8 shows a configuration for estimating the rotational speed of the motor 4 by calculation. As a constant determined by the driving voltage Vt of the EPS motor 4, its counter voltage Ve, and the motor, using the coil resistance R and the coil inductance L, It is possible to calculate the motor speed ω. Where Kt is the torque constant, J is the inertia constant gain of the EPS motor 4, Kb is the counter electromotive force constant, and S is the Laplace conversion parameter. Imtr is the drive current of the EPS motor (4), I ^and the imaginary part represents mtr.

First, there are two relationships.

RImtr + LI + Ve ^and Vt = mtr

Ve = Vt - (RImtr + LI ^and mtr)

In these equations, since LI ^占 mtr is substantially zero at the steering frequency, the following equation holds.

Ve = Vt-RImtr

Therefore, the above-mentioned Equation 11 becomes as follows.

Next, the operation of the road surface reaction torque detector 15 will be described based on the flowchart of FIG. 6. In the flowchart of Fig. 6, in step S105, a time constant? Est is determined based on the expression (10).

Specifically, in step S101, the steering shaft reaction force torque signal Ttran_sens is read out and stored in the memory. In step S102, the vehicle speed detection signal Sveh_sens is read out and stored in the memory. Subsequently, in step S103, the motor rotation detection speed Smtr_sens is read out and stored in the memory. Based on vehicle speed Sveh in step S104, the ratio Kalign with respect to the steering angle of the road surface reaction force torque is calculated | required according to FIG. In step S105, the time constant? Est of the low pass filter element 151 is obtained from the motor rotation speed Smtr_sens and the ratio Kalign. Subsequently, the steering shaft reaction force torque signal Ttran_sens is input to the low pass filter element 151 at step S106, and filtered by the low pass filter operation. In step S107, the road surface reaction force torque estimation value Ttire_est is obtained.

According to the first embodiment, when the steering speed is changed by determining the time constant of the low pass filter element 151 in response to the steering speed by the vehicle speed Sveh and the rotation speed Smtr of the EPS motor 4. And even if the vehicle speed changes, the road reaction force torque can be estimated.

Further, in the first embodiment, the gear ratio of the reduction gear 7 which transmits the assist torque (Tassist) from the EPS motor 4 to the steering shaft 1A is Ggear, and the normal friction torque of the EPS motor 4 is Tfric. When the friction torque in the steering mechanism is Tfrp and the ratio of the steering angle of the road reaction force torque corresponding to the vehicle speed Sveh is Kalign, and the steering speed obtained from the motor rotation speed Smtr is ωs, the low pass filter element 151 The time constant of τest is

τest = (Ggear × Tfric + Tfrp) / Kalign × ωs

Since it is determined by the equation represented by, the low-pass filter that minimizes the estimation error regardless of the traveling pattern by setting the time constant τest of the low-pass filter element 151 by this equation. The element 151 can be used, and the estimation precision of road surface reaction force torque improves.

Second embodiment

Fig. 9 is a configuration diagram showing the electric power steering control device according to the second embodiment of the present invention, in which the portion 10A enclosed by a dashed line is connected to the drive current Imtr of the motor 4. Block that computes the target value for In the second embodiment, instead of the road reaction force torque detector 15 shown in Figs. 4 and 5, a road reaction force torque detector 15A is used. Fig. 10 is a configuration diagram showing the road reaction force torque detector 15A of the electric power steering control device according to the second embodiment of the present invention, wherein a portion surrounded by a dashed line corresponds to the road reaction force torque detector 15A. do.

In Fig. 9, 11 to 20 are the same as those in Fig. 4, but a road surface reaction force torque detector 15A is used. This road surface reaction force torque detector 15A includes blocks 21A, 22, 23, and 24, as shown in FIG. Blocks 22, 23, and 24 are the same as in FIG. In the second embodiment, the block 21A is a steering shaft reaction torque signal calculating block for calculating the steering shaft reaction torque signal Ttran_sens, and the steering torque signal Tsens from the steering torque detector 12 and the motor current. The motor current signal Imtr_sens from the detector 20 and the motor acceleration signal Amtr_sens from the motor acceleration detector 14 are input to the block 21A, and the steering shaft reaction torque of FIG. 4 with respect to the block 21A ( Ttran) input is deleted. The block 21A is based on the steering torque detection signal Tsens, the motor current detection signal Imtr_sens, and the motor acceleration signal Amtr_senst in accordance with equations (1), (2) and (3). Compute the reaction torque signal (Ttran_sens).

FIG. 11 is a flowchart showing the operation of the road reaction force torque detector 15A of the electric power steering control device according to the second embodiment of the present invention.

In order to obtain the road surface reaction torque signal Ttire_est, the steering shaft reaction torque signal Ttran_sens is filtered by the low pass filter 151. In this embodiment, the steering shaft reaction force Ttran is measured. In the second embodiment, the steering shaft reaction force torque signal Ttran_sens calculated according to the equations (1) and (3) is used. Other than that, FIG. 11 is the same as FIG.

Next, the operation of the road surface reaction torque detector 15A will be described based on the flowchart of FIG. 11. In this flowchart, in step S208, the time constant? Est of the low pass filter 151 is determined based on the equation (10).

Specifically, in step S201, the steering torque detection signal Tsens from the steering torque detector 12 is read out and stored in the memory. In step S202, the motor current detection signal Imtr_sens from the motor current detector 20 is read out and stored in the memory. Subsequently, in step S203, the vehicle speed signal Sveh_sens from the vehicle speed detector 11 is read out and stored in the memory. In step S204, the motor speed detection signal Smtr_sens from the motor speed detector 13 is read out and stored in the memory. In step S205, the motor acceleration signal Amtr_sens from the motor acceleration detector 14 is read out and stored in the memory. Subsequently, the steering shaft reaction torque torque signal Ttran_sens is calculated from the steering torque detection signal Tsens, the motor current detection signal Imtr_sens, and the motor acceleration signal Amtr_sens in step S206 (steering shaft reaction force torque signal output means), and the step In S207, the ratio (Kalign) to the steering angle of the road surface reaction force (alignment torque) is obtained based on the vehicle speed signal Sveh_sens. In step S208, the time constant? Est of the low pass filter element 151 is obtained from the motor speed signal Smtr_sens and the ratio Kalign. Subsequently, the steering shaft reaction force torque signal Ttran_sens is input to the low pass filter element 151 in step S209. In step S210, the road surface reaction force torque estimation value Ttire_est is obtained.

According to the second embodiment, even when the steering shaft reaction force torque Ttran cannot be measured, the same effect as that of the first embodiment can be obtained by calculating the steering shaft reaction force torque signal Ttran_sens.

Third embodiment

12 is a characteristic diagram showing the relationship between the road reaction force and the steering angle of the electric power steering control apparatus according to the third embodiment of the present invention. In FIG. 12, the vertical axis is torque Nm, and the horizontal axis is time (second). Road reaction torque Talign is 1 / 5O and is represented by characteristic E, steering angle θhdl is represented by characteristic F, and steering shaft speed is represented by characteristic G. The steering shaft speed is proportional to the rotational speed of the motor 4.

Fig. 13 is a configuration diagram showing a road reaction force torque detector 15B of the electric power steering control device according to the third embodiment of the present invention, and a portion surrounded by a dashed line corresponds to the road reaction force torque detector 15B. .

In FIG. 13, blocks 21A, 22, 23, 24 are the same as those in FIG. J and K are calculators, J multiplies the motor acceleration signal Amtr_sens by the inertia gain of the EPS motor 4, and K multiplies the motor acceleration signal Amtr_sens by the acceleration gain of the EPS motor 4.

Fig. 14 is a flowchart showing the operation of the road reaction force torque detector 15B of the electric power steering control device according to the third embodiment of the present invention.

Fig. 15 is a block diagram showing another road surface reaction torque detector 15C used in the electric power steering control device according to the third embodiment of the present invention, and the portion surrounded by the dashed-dotted line is the road surface reaction torque detector 15C. Corresponds to

In Fig. 15, 21A, 22, 23, and 24 are the same as those in Fig. 10, but the steering shaft reaction force torque signal Ttran_sens is calculated from the steering torque signal Tsens and the motor current signal Intr_sens.

In the second embodiment, when fast steering is performed, as shown by characteristic E in FIG. 12, when the road reaction force torque Talign causes phase progress with respect to the steering angle θ hdl shown in characteristic F There is. Therefore, the road surface reaction torque Talign begins to decrease faster than the case where the sign of the steering speed is reversed when the steering wheel 1 is turned back, and the equation (5) for the steering shaft reaction torque Ttran is given. Does not hold, and the waveform is delayed from the road reaction torque (Talign).

In order to avoid this phenomenon, it is effective to compensate for the delay of the steering shaft speed. With respect to Equation 1 in the first and second embodiments, in order to compensate for the delay in the steering shaft speed, a proportional gain K to the motor acceleration Sω / dt is obtained as shown in Equation 12 below. ) To compensate.

The calculator J in FIG. 13 calculates the third term of Equation 12, and the calculator K calculates the fourth term.

In FIG. 13, since the whole structure is the same as that of 2nd Example, only the road surface reaction force torque detector 15B is shown.

In order to obtain the road surface reaction torque estimate Ttireest, the steering shaft reaction torque torque signal Ttran_sens is filtered by the low pass filter element 151, and the steering shaft reaction torque torque Ttran at this time is, in the third embodiment, In order to compensate for the delay of the steering shaft speed, according to Equation 12, the term obtained by multiplying the motor acceleration (dω / dt) by the proportional gain (K) was compensated. Other than this is the same as that of 2nd Example.

This operation will be described based on the flowchart of FIG. 14. At this time, in S309, the time constant? Est is determined based on Equation (10).

In step S301, the steering torque detection signal Tsens is read out and stored in the memory. In step S3O2, the motor current detection signal Imtr_sens is read out and stored in the memory. Subsequently, the vehicle speed signal Sveh_sens is read out in step S3O3 and stored in the memory. In step S304, the motor speed signal Smtr_sens is read out and stored in the memory. In step S305, the motor acceleration signal Amtr_sens is read out and stored in the memory. Subsequently, the steering shaft reaction torque torque signal Ttran_sens before phase compensation is calculated on the basis of the steering torque detection signal Tsens, the motor current signal Imtr_sens and the motor acceleration signal Amtr_sens in step S306, and before the phase compensation in step S307. The steering shaft reaction torque torque signal Ttran_sens is calculated by adding the product acceleration (Kxd? / Dt) of the motor acceleration and the proportional gain K to the steering shaft reaction torque signal Ttran_sens. Subsequently, based on the vehicle speed signal Sveh_sens in step S308, the ratio Kalign with respect to the steering angle? Sens of the road surface reaction force torque (alignment torque) Talign is obtained. In step S309, the time constant? Est of the low pass filter element 151 is obtained from the motor speed signal Smtr_sens and the ratio Kalign. Subsequently, the steering shaft reaction force torque signal Ttran_sens phase compensated in step S310 is filtered by the low pass filter element 151. In step S311, the road reaction force torque estimation value Ttire_est is obtained.

According to the third embodiment, the phase-compensated steering shaft reaction torque signal Ttran_sens, which is filtered by the low pass filter element 151, is multiplied by the motor acceleration dω / dt multiplied by the proportional gain K. As a result, it is possible to compensate for the phenomenon in which the road reaction force torque causes phase progression with respect to the steering angle, and to improve the estimation accuracy of the road reaction force torque even in a fast steering pattern.

In addition, when the inertia gain and acceleration gain of the motor are substantially the same, the road surface reaction force torque detector 15C shown in Fig. 15, which ignores the acceleration term in Equations 1 and 12, is used to achieve the second embodiment. The same effect can be obtained. In the road surface reaction torque detector 15C shown in FIG. 15, compared with the road reaction force torque detector 15B shown in FIG. 13, the motor acceleration signal Amtr_sens for the block 21A is deleted, and the calculators J and K are used. ) Is also deleted.

Fourth embodiment

The fourth embodiment uses a road surface reaction force torque detector 15D. The fourth embodiment differs from the first embodiment only in the configuration of the road surface reaction torque detector 15D, and the other is the same as the first embodiment. Therefore, description of the whole structure is abbreviate | omitted.

Fig. 16 is a configuration diagram showing a road surface reaction torque detector 15D of the electric power steering control device according to the fourth embodiment of the present invention, and a portion surrounded by a dashed line corresponds to the road surface reaction torque detector 15D. .

In FIG. 16, blocks 21 to 24 are the same as those in FIG. The block 29 is a time constant upper and lower clip portion which receives the output of the time constant calculating section 23 of the low pass filter element and outputs an upper and lower limit value of the time constant? Est of the low pass filter element 151. Is input to the low pass filter operation unit 24, and clips the time constant [tau] est of the low pass filter element 151 to its upper and lower limits.

Fig. 17 is a flowchart showing the operation of the road reaction force torque detector 15D of the electric power steering control device according to the fourth embodiment of the present invention.

In the first to third embodiments, the road surface reaction force torque (Ttire_est) is obtained by filtering the first axis low pass filter element 151 by the steering shaft reaction force torque signal Ttran_sens, but the fourth embodiment is implemented. An example provides the upper and lower limit values in the time constant? Est of the low pass filter element 151 at this time. Other than this is the same as that of 1st Example.

Next, the operation of the road surface reaction torque detector 15D according to the fourth embodiment will be described based on the flowchart of FIG. 17. Here, in step S410 of Fig. 17, the time constant? Est is determined based on the equation (10).

Specifically, in step S401, the steering shaft reaction force torque signal Ttran_sens is read out and stored in the memory. In step S402, the vehicle speed detection signal Sveh_sens is read out and stored in the memory. In step S403, the motor speed signal Smtr_sens is read out and stored in the memory. In step S4O4, the ratio Kalign with respect to the steering angle? Sens of the road surface reaction torque (alignment torque) Talign is obtained based on the vehicle speed detection signal Sveh_sens. Subsequently, in step S4O5, the time constant? Est of the low pass filter element 151 is obtained from the motor speed signal Smtr_sens and the ratio Kalign. Subsequently, it is determined in step S406 whether the time constant? Est of the low pass filter element 151 is larger than the upper limit value, and when it is large, the time constant is clipped to the upper limit value in step S407, and the flow proceeds to step S41O. When the time constant? Est in step S4O6 is not greater than the upper limit value, it is determined in step S408 whether the time constant? Est of the low pass filter element 151 is smaller than the lower limit value, and when it is small, in step S409 clip est) to a lower limit and proceed to step S410. When the time constant [tau] est is not smaller than the lower limit in step S408, the time constant [tau] est of the low pass filter element 151 is determined in step S410. Subsequently, in step S411, the steering shaft reaction force torque signal Ttran_sens is filtered by the low pass filter element 151. In step S412, the road reaction force torque estimation value Ttire_est is obtained.

When the time constant? Est of the low pass filter element 151 is determined by the calculation of equation (10) from the motor speed Smtr and the vehicle speed Sveh, the time constant? Est of the low pass filter 151 is determined. When the vehicle speed Sveh is low speed or when the steering speed is small, the time constant τest becomes too large, becomes close to the integral operation, and is susceptible to the influence of the offset component from the actual value of the steering shaft reaction force torque signal Ttran_sens. Lose.

On the contrary, when the speed is high or the steering speed is large, the time constant? Est is too small, so that the filter characteristic is not the low pass filter element 151, but the gain characteristic is close to the unwanted noise component. There will be no. By setting an upper and lower limit, such a problem can be solved.

As described above, in the fourth embodiment, since the time constant? Est of the low pass filter element 151 has an upper limit and a lower limit, the road reaction force torque estimation value Ttire_est prevents the error from increasing from the actual value, The divergence of the time constant [tau] est of the pass filter element 151 can be prevented.

Fifth Embodiment

Fig. 18 is a block diagram showing a road reaction force torque detector 15E of the electric power steering control device according to the fifth embodiment of the present invention, and a portion surrounded by a dashed line corresponds to the road reaction force torque detector 15E. .

In Fig. 18, blocks 21 to 24 are the same as those in Fig. 5. The block 30 is a steering speed upper and lower clip portion which receives the input of the motor speed signal Smtr_sens and clips the steering speed to the upper and lower limits.

Considering the driver's control while driving, there is a limit to the steering wheel operating speed in the case of normal driving. In consideration of the steering speed of the driver, for example, the lower limit of the steering speed is 10 deg / s and the upper limit of the steering speed is 450 deg / s, and the road surface reaction torque detector 15E is configured as shown in FIG. In the road reaction force torque detector 15E, the motor speed signal Smtr_sens from the motor speed detector 13 is input to the added block 30, and the output from the block 30 is supplied to the block 23. do. In block 23, the time constant? Est based on the ratio Kalign is calculated under the upper and lower limits of the clipped steering speed from the block 30. By doing in this way, the time constant (tauest) according to the driver's steering speed can be determined.

According to the fifth embodiment, the same effect as in the fourth embodiment can be obtained by determining the time constant? Est corresponding to the steering speed of the driver. In addition, there is an effect of preventing the divergence of the equation (10).

Sixth embodiment

FIG. 19A is a configuration diagram showing a road reaction force torque detector 15F of the electric power steering control device according to the sixth embodiment of the present invention, wherein a portion surrounded by a dashed line is attached to the road reaction force torque detector 15F. It is considerable.

In Fig. 19A, blocks 21 to 24 are the same as those in Fig. 5. The block 31 is a steering speed upper / lower clip portion that receives the motor speed signal Smtr_sens and the vehicle speed signal Sveh_sens and clips the steering speed Shdl to an upper and lower limit corresponding to the vehicle speed Sveh. The relationship between the steering speed Shdl and the vehicle speed Sveh by this block 31 is shown in FIG. 19B. In this FIG. 19B, the vertical axis | shaft is steering speed Shdl and the horizontal axis | shaft is vehicle speed Sveh. The characteristic Lu represents the upper limit of the steering speed Shdl, and the characteristic Ld represents the lower limit.

In consideration of the steering of the driver while driving, in the case of general driving, the vehicle speed Sveh is often performed at a low speed in a low speed range, and is less frequently operated at a slower speed. When the vehicle speed Sveh is a high speed station, steering is often performed slowly, and fast steering is rare. Thus, since the upper and lower limits Lu and Ld of the steering speed Shdl are changed in response to the vehicle speed Sveh, the road surface reaction torque detector 15F is constituted as shown in FIG. 19A. By doing this, it is possible to determine the time constant? Est in response to the steering speed Shdl and the vehicle speed Sveh of the driver.

According to the sixth embodiment, the same effect as in the fourth embodiment can be obtained by determining the time constant? Est in response to the steering speed Shdl and the vehicle speed Sveh of the driver. In addition, there is an effect of preventing the divergence of the equation (10).

Seventh embodiment

20 is a schematic diagram showing an electric power steering control device according to a seventh embodiment of the present invention.

In FIG. 20, the code | symbols 1-3, 5-7 represent the same thing as that of FIG. Reference numeral 8 denotes a planetary gear provided in the steering shaft 1A, 9a denotes a variable gear motor (first motor), and 9b denotes a pinion shaft motor (second motor). The variable gear motor 9a is coupled to the steering shaft 1A via the reduction gear 7, and the pinion shaft motor 9b is coupled to the steering shaft 1A via the planetary gear 8.

20, θhdl is the steering angle of the handle 1, θsens is the steering angle detection signal of the handle 1, Tsens is the steering torque detection signal, Imtr_sens1 is the drive current detection signal of the variable gear motor 9a, Imtr_sens2 is a drive current detection signal of the pinion shaft motor 9b, Vt-sens1 is a drive voltage detection signal of the variable gear motor 9a, Vt_sens2 is a drive voltage detection signal of the pinion shaft motor 9b, and Vsupply1 is a variable gear motor ( Power supply voltage for 9a), Vsupply2 is power supply voltage for pinion shaft motor 9b, Tgear is gear output torque by variable gear motor 9a, Tassist is assist torque by pinion shaft motor 9b, Thdl Is steering torque, Ttran is steering shaft reaction torque, Tfrp is friction torque, and Talign is road reaction torque.

The electric power steering control device of a steering angle superimpose mechanism having a variable gear motor 9a for controlling the gear output torque and a pinion shaft motor 9b for controlling the actual steering angle is handled by a driver. The torque Thdl at the time of bending (1) is measured by the torque sensor 3 as a steering torque detection signal Tsens, and the gear of the variable gear mechanism is shifted in response to the torque detection signal Tsens. ) To generate a gear output torque Tgear in which the steering torque Thdl is multiplied by the variable gear, and the actual steering torque is changed by the pinion shaft motor 9b based on this gear output torque Tgear. The main function is to generate assist torque to assist.

In addition, in order to realize a better steering feeling and steering stability, the steering angle? Hdl of the handle 1, the rotational speed of the motor 9b, or the rotational angular velocity of the motor 9b (differentially obtained when the motor angular acceleration is obtained) Has a sensor to measure). The drive current detection signals Imtr_sens1 Imtr_sens2, the drive voltage detection signals Vt_sens1 and Vt_sens2, and the power supply voltage detection signals Vsupply1 and Vsupply2 of the motors 9a and 9b are also received by the EPS-ECU 5.

Dynamically, the steering torque Thdl is variable geared to the variable gear mechanism, and the sum of the gear output torque and assist torque is adjusted against the steering shaft reaction torque Ttran. Rotate (1A). In addition, when the steering wheel 1 is rotated, the inertia term of the pinion shaft motor 9b also acts, and finally, the relationship of the following expression (13) is established.

The assist torque Tassist by the pinion shaft motor 9b is given by the following expression (14). Imtr2 is the drive current of the motor 9b.

The steering shaft reaction force torque Ttran is the sum of the road surface reaction force torque Talign and the friction torque Tfric_all in the steering mechanism, as shown in Equation 15 below.

In the control device (EPS-ECU 5) of the electric power steering control device, the target value for the drive current Imtr2 of the motor 9b is calculated from the sensor signal described above, and the actual current of the motor 9b is calculated. Is controlled so that the pinion shaft motor 9b generates a predetermined torque obtained by multiplying the drive current value by the torque constant and the gear ratio (between the motor and the steering shaft), and the torque when the driver steers. Is configured to assist.

This configuration is generally referred to as a rudder superimpose, and has a variable gear mechanism that generates a gear output torque by multiplying the driver torque in a link mechanism connecting the handle and the tire, and assists the output gear output torque. It is characterized by assisting by the torque which the pinion shaft motor 9b generate | occur | produced in the form.

A feature of the seventh embodiment is that the road surface reaction force can be obtained in the configuration of the rudder angle superimpose. The gear output torque can be measured by attaching the torque sensor 3 to the gear output torque generating portion of the steering shaft 1A. In addition, the steering shaft reaction force torque Ttran can also be calculated | required by calculation like Formula (13).

The method of obtaining the steering shaft reaction force torque Ttran and then the road surface reaction force torque Ttire_est can apply the method shown in the first to sixth embodiments as it is.

In the seventh embodiment, the gear output torque is detected using a sensor, but even when there is no sensor, an equivalent value is obtained by multiplying the steering torque by the variable gear in a range where the friction of the variable gear mechanism is small.

According to the seventh embodiment, in the configuration of the electric power steering control device, even in the configuration having the steering angle superimposition mechanism, the same effects as in the first to sixth embodiments can be obtained.

According to the seventh embodiment as described above, even if the steering angle superimposed configuration detects the steering shaft reaction force, the road surface reaction force can be estimated even when the steering speed is changed or when the vehicle speed is changed. .

Eighth embodiment

21 is a schematic diagram showing an electric power steering control device according to an eighth embodiment of the present invention.

In Fig. 21, reference numerals 1 to 3 and 5 are the same as those in Fig. 1. 7a and 7b are reduction gears. 10a is a steering reaction force control motor, 10b is an actual steering angle control motor.

Θhd1 is the steering angle of the handle 1, θsens is the steering angle detection signal of the handle 1, Tsens is the steering torque detection signal, Imtr_sens1, Imtr_sens2 are the drive current detection signals of the motors 10a and 10b, Vt_sens1, Vt_sens2 Are their driving voltage detection signals, Vsupply1, Vsupply2 are their power supply voltages, Tassist1, Tassist2 are assist torques from motors 10a, 10b, Thdl is steering torque, Ttran is steering shaft reaction torque, Tfri is friction torque, Talign is Road reaction force torque.

The steering reaction force control motor 10a for controlling the steering reaction force and the actual steering angle control motor 10b for controlling the actual steering angle have no mechanical connection between the handle 1 and the tire 2 operated by the driver. The electric power steering control device of the non-steer-by-wire mechanism measures the steering torque Thdl when the driver turns the steering wheel 1 as the steering torque detection signal Tsens by the torque sensor 3, and the torque detection signal. In response to Tsens, a steering reaction force assist torque Tassist1 for appropriately controlling the steering torque Thdl of the driver in response to the vehicle behavior is generated by the steering reaction force control motor 10a, and furthermore, the motor 10b for the actual steering angle control motor 10b. The main function is to generate an actual steering angle control assist torque (Tassist2) that controls the actual steering angle of the tire 2.

In addition, in order to realize a better steering feeling and steering stability, the steering angle θhdl of the handle 1, the rotation angle of the motors 10a and 10b, or the angular velocity of the motors 10a and 10b (differential motor angular acceleration) May be obtained). In addition, the drive currents Imtr_sens1 and Imtr_sens2 of the motor, the drive voltages Vt_sens1 and Vt_sens2, and the power supply voltages Vsupply1 and Vsupply2 applied between the motor terminals are also received in the EPS-ECU 5.

Dynamically, since the handle and the tire are not connected by a mechanical connection, a completely different relationship is established, and the steering torque Thdl matches the steering reaction force Tasist1, which is generated in the actual steering angle control motor 10b. The assist torque Tasist2 rotates the tire 2 against the steering shaft reaction force torque Ttran. In addition, when the tire 2 is rotated, the inertia term of the actual steering angle control motor 10b also acts, and the following equation (16) holds. ω2 is the angular velocity of the motor 10b.

The assist torque Tassist2 by the actual steering angle control motor 10b is given by the following equation (17).

Ggear2 is the gear ratio of the reduction gear 7b, and Imtr2 is the drive current of the motor 10b.

The steering shaft reaction force torque Ttran is the sum of the road surface reaction force torque Talign and the friction torque Tfric_all in the steering mechanism, as shown in Equation 18 below.

In the control device (EPS-ECU 5) of the electric power steering control device, the target value of the drive current Imtr2 of the motor 10b is calculated from the sensor signal described above, and the actual current of the motor 10b is calculated. The current control is made to match, and the motor 10b is configured to generate a predetermined torque multiplied by a torque constant and a gear ratio (between the motor and the steering shaft) to assist the torque Thdl when the driver is steering. have.

This configuration is generally referred to as a steer-by-wire, and has no mechanical connection between the handle 1 and the tire 2, and the steering reaction force control motor 10a that controls the steering reaction force transmitted to the driver's handle 1. And an actual steering angle control motor 10b for controlling the actual steering angle of the tire 2 from the steering angle and the vehicle condition amount of the driver, and according to this mechanism, there is no mechanical connection, and thus the layout of the vehicle The degree of freedom is increased, and the vehicle can be stabilized regardless of the driver's steering wheel operation. Since the mechanical configuration is different, the physical formula shown in the first embodiment and the formula for calculating the steering shaft reaction force torque Ttarn are different. However, the method for obtaining the steering shaft reaction force torque is shown in the first to sixth embodiments. As described above, the steering shaft reaction force Ttran may be detected by the sensor, or may be calculated according to the equation (16).

The method shown in the first to sixth embodiments can be applied to the method of obtaining the steering axis reaction force Ttran and then the road surface reaction force Trere-est.

According to the eighth embodiment, in the configuration of the electric power steering control device, also in the configuration of the steer-by-wire, the same effects as in the first to sixth embodiments can be obtained, and the handle 1 and the tire can be obtained. The road surface reaction torque estimation value can be used also as a target value of the steering torque generating apparatus in the steering-by-wire apparatus in which (2) is not mechanically connected.

As described above, according to the eighth embodiment, even in the steer-by-wire configuration, by detecting the steering shaft reaction force, the road surface reaction force can be estimated even when the steering speed is changed or when the vehicle speed is changed.

According to the present invention, the time constant of the low pass filter element is determined in response to the steering speed by the vehicle speed and the rotational speed of the EPS motor, so that the road reaction force torque can be estimated even when the steering speed is changed or when the vehicle speed is changed. do.

Claims (1)

In the electric power steering control apparatus which has an electric motor which provides the assist torque which assists a driver's steering torque to the steering shaft connected to the axle, Vehicle speed detecting means for detecting a vehicle speed, Motor speed detecting means for detecting a speed of the electric motor; A steering shaft reaction force torque signal output means for outputting a steering shaft reaction force torque signal in response to the steering shaft reaction force torque acting on the steering shaft; Road surface reaction force detection means for obtaining a road surface reaction force estimation value used for controlling assist torque by filtering the steering shaft reaction force torque signal by a low pass filter operation, And a time constant of the low pass filter operation in accordance with the vehicle speed detected by the vehicle speed detecting means and the motor speed detected by the motor speed detecting means.

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