JP2014177246A - Electric power steering device and program - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce an operation sound of a device and vibration generated in a device by suppressing a torque fluctuation caused by a rotary mechanism part, etc. inside an electric power steering device.SOLUTION: An electric power steering device 100 includes: an electric motor 110 for imparting assist force to steer a wheel 150 for an operation of a steering wheel 101; a torque sensor 109 for detecting steering torque of the steering wheel 101 and generating a torque signal; removing means for removing a torque fluctuation which is generated according to an operation of the steering wheel 101 and in which the frequency changes temporally, from the torque signal generated by the torque sensor 109; and motor control means for controlling the drive of the electric motor 110 by supplying a current set based on the torque signal after the torque fluctuation is removed by the removing means.

Description

  The present invention relates to an electric power steering apparatus and a program.

2. Description of the Related Art In recent years, there has been proposed an electric power steering device that includes an electric motor in a steering system of a vehicle, and assists a driver's steering force with the power of the electric motor to steer wheels.
The drive of the electric motor of this electric power steering device is controlled by a control device. In order to control the drive of the electric motor, the control device first sets a target current to be supplied to the electric motor according to the steering torque, the vehicle speed, and the like.

For example, Patent Document 1 discloses a first rotating shaft coupled to a steering wheel, a rack shaft that steers a steered wheel, a second rotating shaft that linearly moves the rack shaft, a torsion bar, and a steering wheel. An electric motor for applying an assist force to the operation of the steering wheel, a steering torque detecting means for detecting the steering torque of the steering wheel, and a target current for setting a target current to be supplied to the electric motor based on the steering torque detected by the steering torque detecting means And a target current calculation unit that controls a resonance compensation unit that suppresses a resonance frequency component of a control system including the torsion bar as a spring element and the electric motor, the second rotation shaft, and the rack shaft as an inertia element. An electric power source that is provided on the output side of the detection means and sets a target current according to the steering torque whose resonance frequency component is suppressed by the resonance compensator Power steering apparatus is disclosed.
Patent Document 2 also removes a signal having a resonance frequency caused by a spring element of a torque sensor system and handle inertia in an all-electric power steering device that assists the steering force with a motor in accordance with torque applied to the handle. A band drive filter that includes a motor drive control system is disclosed.

JP 2010-234777 A JP-A-2-164665

Here, torque fluctuation may occur in the detected steering torque due to a rotation mechanism portion or the like inside the electric power steering apparatus. This torque fluctuation has a characteristic that the frequency changes with time in response to the driver's operation of the steering wheel. When this torque fluctuation occurs, the target current promotes the fluctuation, and as a result, the torque fluctuation of the assist torque is further increased. In this case, the operation sound of the device and the vibration generated in the device are likely to increase.
It is an object of the present invention to reduce the operating noise of the device and the vibration generated in the device by suppressing torque fluctuations caused by a rotating mechanism part or the like inside the electric power steering device.

  For this purpose, the present invention provides an electric motor for providing an assist force for turning a wheel in response to an operation of the steering wheel, a torque detecting means for detecting a steering torque of the steering wheel and generating a torque signal, and torque detection. Based on the torque signal generated by the means, the removing means for removing the torque fluctuation generated in response to the operation of the steering wheel and the frequency changing with time, and the torque signal after the torque fluctuation is removed by the removing means An electric power steering apparatus comprising: motor control means for controlling driving of the electric motor by supplying a set current.

Here, it is preferable that a calculation unit that calculates a frequency of torque fluctuation is further provided, and the removal unit removes the torque fluctuation of the frequency calculated by the calculation unit.
The calculating means preferably calculates the frequency of torque fluctuation based on at least one of the steering speed of the steering wheel and the rotational speed of the electric motor. The calculating means calculates the steering wheel frequency with respect to a predetermined basic frequency. More preferably, the frequency of torque fluctuation is calculated by multiplying a coefficient determined for at least one of the turning speed and the rotational speed of the electric motor.
Further, it can be understood that the torque fluctuation is caused by the rotation mechanism portion inside the apparatus.

  The present invention also provides a computer with a function of acquiring a torque signal from torque detecting means for detecting steering torque of the steering wheel, and a frequency of torque fluctuation that occurs according to the operation of the steering wheel and whose frequency changes with time. A function to remove the torque fluctuation of the calculated frequency from the acquired torque signal, and an assist to steer the wheel in response to the operation of the steering wheel based on the torque signal after the torque fluctuation is removed And a function for setting a current to be supplied to the electric motor for applying force.

  The present invention can reduce the operating noise of the device and the vibration generated in the device by suppressing the torque fluctuation caused by the rotation mechanism part or the like inside the electric power steering device.

It is a figure showing the schematic structure of the electric power steering device concerning a 1st embodiment. It is a schematic block diagram of the control apparatus of the electric power steering apparatus which concerns on 1st Embodiment. It is the figure explaining the steering torque detected by a torque sensor, the target current, and the assist torque by an electric motor. It is a schematic block diagram of the target current calculation part which concerns on 1st Embodiment. It is a schematic block diagram of the control part which concerns on 1st Embodiment. It is a flowchart explaining operation | movement of the electric power steering apparatus which concerns on 1st Embodiment. It is a figure which shows schematic structure of the electric power steering apparatus which concerns on 2nd Embodiment. It is a schematic block diagram of the control apparatus of the electric power steering apparatus which concerns on 2nd Embodiment. It is a schematic block diagram of the target current calculation part which concerns on 2nd Embodiment. It is the flowchart explaining operation | movement of the electric power steering apparatus which concerns on 2nd Embodiment.

  Embodiments of the present invention will be described below in detail with reference to the accompanying drawings.

[First embodiment]
First, the first embodiment will be described.
<Description of the entire electric power steering device>
FIG. 1 is a diagram showing a schematic configuration of an electric power steering apparatus 100 according to the first embodiment.
An electric power steering device 100 (hereinafter, also simply referred to as “steering device 100”) is a steering device for arbitrarily changing the traveling direction of a vehicle. In the present embodiment, the configuration applied to a vehicle is used. Illustrated.

  The steering device 100 includes a wheel-like steering wheel (handle) 101 operated by a driver, and a steering shaft 102 provided integrally with the steering wheel 101. The steering shaft 102 and the upper connection shaft 103 are connected via a universal joint 103a, and the upper connection shaft 103 and the lower connection shaft 108 are connected via a universal joint 103b.

  The steering device 100 includes a tie rod 104 connected to each of the left and right wheels 150 as rolling wheels, and a rack shaft 105 connected to the tie rod 104. Further, the steering device 100 includes a pinion 106 a that constitutes a rack and pinion mechanism together with rack teeth 105 a formed on the rack shaft 105. The pinion 106 a is formed at the lower end portion of the pinion shaft 106.

  The steering device 100 also has a steering gear box 107 that houses the pinion shaft 106. The pinion shaft 106 is connected to the lower connection shaft 108 via a torsion bar in a steering gear box 107. Inside the steering gear box 107, a torque sensor 109 is provided as an example of torque detecting means for detecting the steering torque of the steering wheel 101 based on the relative angle between the lower connecting shaft 108 and the pinion shaft 106 and generating a torque signal. It has been. Further, the steering device 100 is provided with a turning angle sensor 160 that detects a steering angle of the steering wheel 101 and generates a turning speed signal.

The steering device 100 includes an electric motor 110 supported by the steering gear box 107, and a speed reducing mechanism 111 that decelerates the driving force of the electric motor 110 and transmits it to the pinion shaft 106. Electric motor 110 according to the present embodiment is a three-phase brushless motor. The magnitude and direction of the actual current that actually flows through the electric motor 110 is detected by the motor current detector 33 (see FIG. 5).
The steering device 100 includes a control device 10 that controls the operation of the electric motor 110. The control device 10 includes a vehicle speed sensor 170 that detects a torque signal Td that is an output value of the torque sensor 109 described above, a turning speed signal R that is an output value of the turning angle sensor 160, and a vehicle speed Vc that is a moving speed of the vehicle. The vehicle speed signal v which is the output value of is input.

  The steering device 100 configured as described above detects the steering torque T applied to the steering wheel 101 by the torque sensor 109, drives the electric motor 110 in accordance with the detected torque, and generates torque generated by the electric motor 110. Is transmitted to the pinion shaft 106. Thereby, the torque generated by the electric motor 110 assists the driver's steering force applied to the steering wheel 101. In other words, the electric motor 110 gives an assist force for turning the wheel 150 in response to the operation of the steering wheel 101.

<Description of Control Device 10>
Next, the control device 10 will be described.
FIG. 2 is a schematic configuration diagram of the control device 10 of the electric power steering device 100 according to the first embodiment.
The control device 10 is an arithmetic and logic circuit composed of a CPU, ROM, RAM, backup RAM, and the like. Actually, the control device 10 is realized by an ECU (Electronic Control Unit) or the like.
The control device 10 includes a torque signal Td obtained by converting the steering torque T detected by the torque sensor 109 described above into an output signal, a turning speed signal R detected by the turning angle sensor 160, and a vehicle speed sensor. A vehicle speed signal v obtained by converting the vehicle speed Vc detected at 170 into an output signal is input.
The control device 10 calculates a target torque based on the torque signal Td, and calculates a target current required for the electric motor 110 to supply the target torque, and a target current calculation unit. And a control unit 30 that performs feedback control or the like based on the target current calculated by 20.

  Here, the torque signal Td may have a torque fluctuation that occurs in response to the operation of the steering wheel 101 and changes in frequency. This occurs due to, for example, a rotation mechanism unit inside the steering device 100. More specifically, it occurs due to meshing of gears used in the steering device 100, driving of the electric motor 110, or the like. For example, when the gear rotates, the torque generated between the gears varies depending on whether the gears are engaged with each other or when the gears are disengaged. This causes a torque fluctuation in the steering torque T, and as a result, a torque fluctuation also occurs in the torque signal Td. The frequency of the torque fluctuation changes with time according to the steering speed of the steering wheel 101. That is, when the operation of the steering wheel 101 is slow (when the steering speed of the steering wheel 101 is small), the rotation mechanism section rotates slowly according to the operation of the steering wheel 101, and therefore the frequency of torque fluctuation becomes small. On the other hand, as the operation of the steering wheel 101 becomes faster (as the steering speed of the steering wheel 101 becomes larger), the rotation mechanism section rotates faster according to the operation of the steering wheel 101, and the frequency of torque fluctuation becomes It has a feature that becomes larger.

FIG. 3 is a diagram illustrating the steering torque T detected by the torque sensor 109, the target current, and the assist torque by the electric motor 110.
Here, the horizontal axis represents time. The vertical axis represents the steering torque T, the assist torque, and the target current. The amounts are represented by the left vertical axis in the case of the steering torque T and the assist torque, and the right vertical axis in the case of the target current. It is represented by
In FIG. 3, the steering torque T indicated by a one-dot chain line has a torque fluctuation with a period of about 0.05 (s) (about 20 Hz) and an amplitude of about 0.5 (N · m). The target current calculated from the steering torque T is indicated by a dotted line. The assist torque generated by the target current is indicated by a solid line. As with the steering torque T, the target current and the assist torque have a variation of 20 Hz. The assist torque has a torque variation with an amplitude of about 1.0 (N · m).
When torque fluctuation occurs in the steering torque T as described above, the target current promotes the fluctuation, and as a result, the torque fluctuation of the assist torque becomes larger.

  In the example of FIG. 3, the fluctuation frequency of the steering torque T, the target current, and the assist torque is about 20 Hz in any time zone, because the sampling time is short. Actually, since the speed at which the driver operates the steering wheel 101 varies with time, this variation frequency also varies with time.

  And when the torque fluctuation of the assist torque by the electric motor 110 is large, the operation sound of the steering device 100 becomes loud and the vibration becomes large and the torque ripple is deteriorated. Such a torque fluctuation caused by the structure of the steering device 100 is difficult to counter by mechanical improvement.

  Therefore, in the present embodiment, the target current calculation unit 20 is configured as follows to suppress this problem.

<Description of Target Current Calculation Unit 20>
FIG. 4 is a schematic configuration diagram of the target current calculation unit 20 according to the first embodiment.
The target current calculation unit 20 includes a base current calculation unit 21 that calculates a base current that serves as a reference for setting the target current, an inertia compensation current calculation unit 22 that calculates a current for canceling the inertia moment of the electric motor 110, and And a damper compensation current calculation unit 23 for calculating a current for limiting the rotation of the motor. The target current calculation unit 20 includes a target current determination unit 25 that determines a target current based on values calculated by the base current calculation unit 21, the inertia compensation current calculation unit 22, and the damper compensation current calculation unit 23, and a torque. A torque fluctuation frequency calculation unit 26 that calculates the frequency of fluctuation, a torque fluctuation removal unit 27 that removes torque fluctuation of a predetermined frequency from the steering torque T, and a phase compensation unit 28 that performs phase compensation of the torque signal are provided. .

  The target current calculation unit 20 receives a torque signal Td, a turning speed signal R, a vehicle speed signal v, a rotation speed signal Nms obtained by converting the rotation speed Nm of the electric motor 110 into an output signal, and the like. The rotational speed signal Nms is, for example, a sensor configured to detect a rotational position of a rotor (rotor) of the electric motor 110 that is a three-phase brushless motor (for example, a rotor configured by a resolver, a rotary encoder, or the like that detects the rotational position of the rotor) It can be exemplified that the value obtained by differentiating the rotation angle of the electric motor 110 detected by the position detection circuit) is converted into an output signal.

  The base current calculation unit 21 further applies a torque signal Ts whose phase has been compensated by the phase compensation unit 28 to the torque signal Tp from which torque variation has been removed from the torque signal Td by a torque variation removal unit 27 described later, and a vehicle speed sensor 170. The base current Ib is calculated based on the vehicle speed signal v from and the base current signal Imb including the information on the base current Ib is output. For example, the base current calculation unit 21 creates a map showing the correspondence between the torque signal Ts and the vehicle speed signal v and the base current Ib, which is previously created based on an empirical rule and stored in the ROM, and the torque signal Ts and The base current Ib is calculated by substituting the vehicle speed signal v.

  The inertia compensation current calculation unit 22 calculates an inertia compensation current for canceling the inertia moment of the electric motor 110 and the system based on the torque signal Tp and the vehicle speed signal v, and generates an inertia compensation current signal Is including information on the current. Output. For example, the inertia compensation current calculation unit 22 generates a torque signal Tp on a map indicating the correspondence between the torque signal Tp, the vehicle speed signal v, and the inertia compensation current, which is previously created based on an empirical rule and stored in the ROM. And the inertia compensation current is calculated by substituting the vehicle speed signal v.

  The damper compensation current calculation unit 23 calculates a damper compensation current for limiting the rotation of the electric motor 110 based on the torque signal Tp, the vehicle speed signal v, and the rotation speed signal Nms of the electric motor 110, and information on this current A damper compensation current signal Id including is output. The damper compensation current calculation unit 23 indicates, for example, the correspondence between the torque compensation signal Tp, the vehicle speed signal v, and the rotation speed signal Nms, which are previously created based on empirical rules and stored in the ROM, and the damper compensation current. The damper compensation current is calculated by substituting the torque signal Tp, the vehicle speed signal v, and the rotational speed signal Nms into the map.

  The target current determination unit 25 is calculated by the base current signal Imb calculated by the base current calculation unit 21, the inertia compensation current signal Is calculated by the inertia compensation current calculation unit 22, and the damper compensation current calculation unit 23. A target current is determined based on the damper compensation current signal Id, and a target current signal ITF including information on this current is output. The target current determination unit 25, for example, previously created a compensation current obtained by adding the inertia compensation current to the base current Ib and subtracting the damper compensation current based on an empirical rule, and stored it in the ROM. The target current is calculated by substituting it into a map showing the correspondence between the compensation current and the target current.

The torque fluctuation frequency calculation unit 26 is an example of a calculation unit that calculates the frequency of torque fluctuation. In the present embodiment, the torque fluctuation frequency calculation unit 26 acquires the turning speed signal R. Based on the turning speed of the steering wheel 101 represented by the turning speed signal R, the frequency of this torque fluctuation is calculated.
Specifically, the frequency of torque fluctuation is calculated by multiplying a predetermined basic frequency by a coefficient determined with respect to the steering speed of the steering wheel 101. That is, for example, when the torque fluctuation generated when the steering wheel 101 is rotated at a speed of 1 rotation / s as the turning speed of the steering wheel 101 is 20 Hz, this 20 Hz is set as the fundamental frequency, for example. Then, using the rotational speed of the steering wheel 101 as a coefficient, the frequency of torque fluctuation is calculated by multiplying this coefficient by 20 Hz. For example, the coefficient when the steering wheel 101 is rotated at a speed of 2 rotations / s is 2, and the frequency of torque fluctuation is 20 Hz × 2 = 40 Hz.

The torque fluctuation removing unit 27 is an example of a removing unit that removes a torque fluctuation that is generated according to the operation of the steering wheel 101 and whose frequency changes with time from the torque signal Td generated by the torque sensor 109.
The torque fluctuation removing unit 27 removes the torque fluctuation having the frequency calculated by the torque fluctuation frequency calculating unit 26. Specifically, the torque fluctuation removal unit 27 is a band removal filter that removes frequencies including the calculated frequency, and changes the frequency band to be removed in accordance with the frequency calculated by the torque fluctuation frequency calculation unit 26. . Then, the torque variation can be removed by performing the filter processing by the band elimination filter on the torque signal Td.
In addition, as a range of the frequency which the torque fluctuation removal part 27 can remove, it is preferable to cover the area | region from about 20 kHz which is the upper limit of a human audible range from the area | region exceeding 0 Hz.

<Description of Control Unit 30>
Next, the control unit 30 will be described in detail.
FIG. 5 is a schematic configuration diagram of the control unit 30 according to the first embodiment.
The control unit 30 of the present embodiment is an example of a motor control unit that controls the driving of the electric motor 110 by supplying a current set based on the torque signal after the torque fluctuation is removed. The control unit 30 detects a motor drive control unit 31 that controls the operation of the electric motor 110, a motor drive unit 32 that drives the electric motor 110, an actual current that actually flows through the electric motor 110, and an actual current detection signal Im. Is output to the motor drive control unit 31.
The motor drive control unit 31 is supplied to the target current finally determined by the target current calculation unit 20 (value indicated by the target current signal ITF) and the electric motor 110 detected by the motor current detection unit 33. A feedback (F / B) control unit 40 that performs feedback control based on a deviation from the actual current (value indicated by the actual current detection signal Im), and a PWM (pulse width modulation) signal for PWM driving the electric motor 110 And a PWM signal generation unit 60 for generation.

  The feedback control unit 40 includes a deviation calculation unit 41 for obtaining a deviation between the target current finally determined by the target current calculation unit 20 and the actual current detected by the motor current detection unit 33, and the deviation is zero. A feedback (F / B) processing unit 42 for performing feedback processing.

The feedback (F / B) processing unit 42 performs feedback control so that the target current and the actual current coincide with each other. For example, the feedback (F / B) processing unit 42 is proportional to the deviation calculated by the deviation calculating unit 41 with a proportional factor. Then, integration processing is performed by the integration element, and these values are added by the addition operation unit.
The PWM signal generation unit 60 generates a PWM signal for driving the electric motor 110 by PWM (pulse width modulation) based on the output value from the feedback control unit 40, and outputs the generated PWM signal 60a.

The motor drive unit 32 is a so-called inverter, and includes, for example, six independent transistors (FETs) as switching elements. Three of the six transistors are a positive line of a power source, an electric coil of each phase, The other three transistors are connected to the electric coil of each phase and the negative side (ground) line of the power source. Then, the driving of the electric motor 110 is controlled by driving the gates of two transistors selected from the six and switching the transistors.
The motor current detection unit 33 detects the value of the actual current flowing through the electric motor 110 from the voltage generated at both ends of the shunt resistor connected to the motor drive unit 32.

<Description of Operation of Electric Power Steering Device 100>
Next, the operation of the electric power steering apparatus 100 will be described.
FIG. 6 is a flowchart for explaining the operation of the electric power steering apparatus 100 according to the first embodiment.
First, when the driver operates the steering wheel 101, the turning angle sensor 160 detects the turning speed of the steering wheel 101 and outputs a turning speed signal R (step 101).
The torque sensor 109 detects the steering torque T of the steering wheel 101 and outputs a torque signal Td (step 102).

The turning speed signal R is acquired by the torque fluctuation frequency calculation unit 26 of the target current calculation unit 20 (step 103).
Then, the torque fluctuation frequency calculation unit 26 calculates the frequency of torque fluctuation generated in the steering torque T based on the steering speed signal R (step 104). As described above, this can be calculated by, for example, multiplying a predetermined basic frequency by a coefficient determined with respect to the turning speed of the steering wheel 101.

On the other hand, the torque signal Td is acquired by the torque fluctuation removing unit 27 of the target current calculating unit 20 (step 105).
Then, the torque fluctuation removing unit 27 removes the torque fluctuation of the frequency calculated by the torque fluctuation frequency calculating unit 26 from the torque signal Td and outputs the torque signal Tp (step 106).

The torque signal Tp output from the torque fluctuation removal unit 27 is phase-compensated by the phase compensation unit 28 to become the torque signal Ts (step 107).
Next, the torque signal Tp and the torque signal Ts are sent to the base current calculation unit 21, inertia compensation current calculation unit 22, and damper compensation current calculation unit 23, and after the base current, inertia compensation current, and damper compensation current are calculated, respectively. The base current signal Imb, the inertia compensation current signal Is, and the damper compensation current signal Id are output (step 108).
Then, the target current determination unit 25 determines a target current based on the base current signal Imb, the inertia compensation current signal Is, and the damper compensation current signal Id, and outputs a target current signal ITF (step 109).

Further, as explained in FIG. 5, the control unit 30 controls the operation of the electric motor 110 based on the target current signal ITF (step 110).
As a result, the electric motor 110 gives an assist force for turning the wheel 150 in response to the operation of the steering wheel 101.

  In the first embodiment described above, the turning angle sensor 160 is provided, and the torque fluctuation frequency calculation unit 26 calculates the frequency of torque fluctuation generated in the steering torque T based on the steering speed signal R. The embodiment is not limited to such an embodiment. The torque fluctuation frequency calculating unit 26 may calculate a turning speed based on the rotation speed Nm of the electric motor 110 and calculate a frequency of torque fluctuation generated in the steering torque T based on the calculated turning speed.

[Second Embodiment]
Next, a second embodiment will be described.
In the first embodiment, the frequency of torque fluctuation is calculated based on the steering speed of the steering wheel 101. In the second embodiment, the frequency of torque fluctuation is calculated based on the rotational speed of the electric motor 110. To do. That is, since the steering speed of the steering wheel 101 and the rotational speed of the electric motor 110 are in a proportional relationship, the rotational speed of the electric motor 110 can be used instead of the steering speed of the steering wheel 101.
Hereinafter, the second embodiment will be described.

FIG. 7 is a diagram showing a schematic configuration of the electric power steering apparatus 100 according to the second embodiment.
The electric power steering apparatus 100 shown in FIG. 7 has the same configuration as the electric power steering apparatus 100 shown in FIG. 1 except that the turning angle sensor 160 is not provided.
Therefore, the torque signal Td that is the output value of the torque sensor 109 and the output value of the vehicle speed sensor 170 that detects the vehicle speed Vc that is the moving speed of the vehicle are input to the control device 10, but the turning speed signal R is not input. .

FIG. 8 is a schematic configuration diagram of the control device 10 of the electric power steering device 100 according to the second embodiment.
When comparing the control device 10 of FIG. 8 with the control device 10 of FIG. 2, a target current calculation unit 20 that calculates a target current, and a control unit that performs feedback control and the like based on the target current calculated by the target current calculation unit 20 30 is the same.
However, as described with reference to FIG. 7, since the turning speed signal R is not input, the difference is that the torque signal Td excluding the turning speed signal R and the vehicle speed signal v are input to the target current calculation unit 20.

Furthermore, FIG. 9 is a schematic configuration diagram of the target current calculation unit 20 according to the second embodiment.
The target current calculation unit 20 in FIG. 9 has substantially the same functional configuration when compared with the target current calculation unit 20 in FIG. That is, the target current calculation unit 20 of FIG. 9 is similar to the target current calculation unit 20 of FIG. 4 in that the base current calculation unit 21, the inertia compensation current calculation unit 22, the damper compensation current calculation unit 23, and the target current determination A unit 25, a torque fluctuation frequency calculation unit 26, a torque fluctuation removal unit 27, and a phase compensation unit 28 are provided.
However, the target current calculation unit 20 in FIG. 9 is different in that the turning speed signal R is not input to the torque fluctuation frequency calculation unit 26 but the rotation speed signal Nms is input. That is, the torque fluctuation frequency calculation unit 26 acquires a rotation speed signal Nms that represents the rotation speed of the electric motor 110. Based on the rotational speed of the electric motor 110, the frequency of torque fluctuation is calculated. The operation of other functional components is the same as in FIG.

  In addition, about the control part 30, the electric power steering apparatus 100 of 2nd Embodiment is the same as that of the case of 1st Embodiment demonstrated in FIG.

FIG. 10 is a flowchart for explaining the operation of the electric power steering apparatus 100 according to the second embodiment.
Here, first, a sensor that detects the rotational position of the rotor of the electric motor 110 detects the rotational speed of the electric motor 110 and outputs a rotational speed signal Nms (step 201).
The torque sensor 109 detects the steering torque T of the steering wheel 101 and outputs a torque signal Td (step 202).

The rotation speed signal Nms is acquired by the torque fluctuation frequency calculation unit 26 of the target current calculation unit 20 (step 203).
The torque fluctuation frequency calculation unit 26 calculates the frequency of torque fluctuation generated in the steering torque T based on the rotation speed signal Nms (step 204).
Steps 205 to 210 below are the same as steps 105 to 110 in FIG.

  In the steering device 100 described in detail above, it is possible to remove, from the torque signal Td, torque fluctuations that occur according to the operation of the steering wheel 101 and whose frequency changes with time. Therefore, the operation sound of the steering device 100 can be reduced, and vibration can be reduced.

In the above-described example, only one of the steering speed of the steering wheel 101 and the rotational speed of the electric motor 110 is used. However, the present invention is not limited to this, and both may be used in combination.
Moreover, although the case where only one type of torque variation has been described in the above-described example, the present invention is not limited to this. Since there are usually a plurality of rotation mechanism portions that cause torque fluctuation in the steering device 100, the frequency of torque fluctuation may be calculated for each of them to perform processing for removing torque fluctuation.
In the above-described example, the configuration applied to the pinion type electric power steering apparatus has been described, but the configuration is not particularly limited. The present invention may be applied to other types of electric power steering devices such as a rack assist type. When applied to a rack-assist type electric power steering device, it is preferable to take into account torque fluctuations due to driving of the ball screw.

<Description of the program>
Note that the processing performed by the control device 10 in the present embodiment can be realized by cooperation of software and hardware resources. In this case, a CPU (not shown) inside the control computer provided in the control device 10 executes a program for realizing each function of the control device 10 to realize each of these functions.

  Therefore, the processing performed by the control device 10 is generated in accordance with the function of acquiring the torque signal Td from the torque sensor 109 that detects the steering torque T of the steering wheel 101 and the operation of the steering wheel 101, and the frequency is temporally generated. The steering wheel 101 is based on the function of calculating the frequency of the changing torque fluctuation, the function of removing the torque fluctuation of the calculated frequency from the acquired torque signal Td, and the torque signal after the torque fluctuation is removed. And a function of setting a current to be supplied to the electric motor 110 that provides an assist force for turning the wheel 150 in response to the operation of the above.

  The program for realizing the present embodiment can be provided not only by communication means but also by storing it in a recording medium such as a CD-ROM.

DESCRIPTION OF SYMBOLS 10 ... Control apparatus, 20 ... Target electric current calculation part, 25 ... Target electric current determination part, 26 ... Torque fluctuation frequency calculation part, 27 ... Torque fluctuation removal part, 30 ... Control part, 100 ... Electric power steering apparatus, 101 ... Steering wheel (Handle), 109 ... torque sensor, 110 ... electric motor, 150 ... wheel, 160 ... turning angle sensor

Claims (6)

An electric motor for providing an assisting force to steer the wheel in response to the operation of the steering wheel;
Torque detecting means for detecting a steering torque of the steering wheel and generating a torque signal;
Removing means for removing, from the torque signal generated by the torque detecting means, torque fluctuations that occur according to the operation of the steering wheel and whose frequency changes with time;
Motor control means for controlling the drive of the electric motor by supplying a current set based on the torque signal after the torque fluctuation is removed by the removing means;
An electric power steering apparatus comprising: A calculation means for calculating a frequency of torque fluctuation;
The electric power steering apparatus according to claim 1, wherein the removing unit removes a torque fluctuation having a frequency calculated by the calculating unit.   The electric power steering apparatus according to claim 2, wherein the calculating unit calculates a frequency of torque fluctuation based on at least one of a steering speed of the steering wheel and a rotation speed of the electric motor.   The calculating means calculates a frequency of torque fluctuation by multiplying a predetermined basic frequency by a coefficient determined for at least one of a steering speed of the steering wheel and a rotation speed of the electric motor. The electric power steering apparatus according to claim 3.   The electric power steering apparatus according to any one of claims 1 to 4, wherein the torque fluctuation is caused by a rotation mechanism portion inside the apparatus. On the computer,
A function of obtaining a torque signal from a torque detection means for detecting a steering torque of the steering wheel;
A function of calculating a frequency of torque fluctuation that occurs in response to the operation of the steering wheel and the frequency changes with time;
A function of removing torque fluctuation of the calculated frequency from the acquired torque signal;
A function of setting an electric current to be supplied to an electric motor for applying an assist force for turning the wheel in response to the operation of the steering wheel, based on a torque signal after torque fluctuation is removed;
A program that realizes

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