Engine control device, engine control method, engine module and electric power steering device

Abstract

Control device (100) used in an electric power steering device (1000) comprising a motor (543), wherein the control device (100) controls the motor (543), the control device (100) having the following features: a model sequence control (230) which generates a correction torque based on an output from a control target (220), which is the motor (543), and which corrects an input to the control target (220) with the correction torque, wherein the model sequence control (230) comprising a high-pass filter (233) with a first cutoff frequency and a low-pass filter (232) with a second cutoff frequency that is higher than the first cutoff frequency, wherein an estimated disturbance torque ^T d is subjected to a filtering process by the low-pass filter (232) and the high-pass filter (233) connected in series with it, characterized by the fact that the model following control (230) is configured such that a transfer function P(s) of the control target (220) is restricted to a target model in a frequency band in which a gain in a gain characteristic of Q(s)·HPF(s) is 1, where Q(s) is a transfer function of the low-pass filter and HPF(s) is a transfer function of the high-pass filter.

Description

[0001] The present disclosure relates to a control device that controls a motor of an electric power steering system according to the preamble of claim 1, to a computer-implemented method for controlling a motor of an electric power steering system according to the preamble of claim 6, to a motor module with such a control device and to an electric power steering system with such a motor module.

[0002] A typical automobile has an electric power steering (EPS) device, which includes an electric motor (hereinafter referred to simply as the "motor") and a motor control device. The electric power steering device is a device that assists the driver in operating the steering wheel by driving the motor. In related technology, the motor power is achieved through torque control in response to steering torque, thereby assisting the steering process.

[0003] JP H06-219310 A and WO 2016 / 208665 A1 each disclose a technique relating to disturbance observer control. JP H06-219310 A uses a robust control system to reduce the influence of a disturbance or parameter fluctuation of a control target on the steering control. WO 2016 / 208665 A1 uses a resonance point disturbance control system, which includes a disturbance observer, to suppress a resonance point disturbance excited at a resonance point of a suspension in a forward-backward direction. JP 2005-88610 A discloses a technique for generating an appropriate steering response force without the discomfort of a road surface reaction force by eliminating a frictional torque generated by internal friction of a steering mechanism.DE 10 2017 112 952 A1 discloses a generic control device for an electric power steering system, wherein a modeling device determines an estimated torque which is filtered by means of a high-pass filter and a low-pass filter.

[0004] It is desirable to improve the steering feel for the driver when the driver's steering process is assisted.

[0005] In recent years, market requirements for noise, vibration, and harshness (NVH), for which a standard exists that is used to evaluate the ride comfort of automobiles, have become increasingly stringent. However, conventional torque control is particularly susceptible to high-frequency interference and cannot suppress high-frequency torque fluctuations, thus making it difficult to meet these market demands.

[0006] In the related technique, a friction model is created as a function of the angular velocity ω of a motor, and friction compensation control is performed using this model. However, with general friction characteristics, the problem is that flutter is likely to occur because the sign of the frictional torque is rapidly reversed at the point when the angular velocity ω of the motor is zero.

[0007] The object of the present invention is to provide a control device, a motor module, an electric power steering device and a computer-implemented method for controlling a motor of an electric power steering device with improved characteristics.

[0008] The problem is solved by a control device according to claim 1, a motor module according to claim 4, an electric power steering device according to claim 5 and a method according to claim 6.

[0009] In a non-limiting and exemplary embodiment, a control device of the present disclosure is a control device used in an electric power steering device comprising a motor, wherein the control device controls the motor, and wherein the control device has the following features: a model-following control that generates a correction torque based on an output from a control target, which is the motor, and that corrects an input to the control target with the correction torque, wherein the model-following control comprises a high-pass filter with a first cutoff frequency and a low-pass filter with a second cutoff frequency that is higher than the first cutoff frequency and is configured such that a transfer function of the control target is restricted to a target model in a frequency band in which a gain in a gain characteristic of Q(s)·HPF(s) is 1.where Q(s) is a transfer function of the low-pass filter and HPF(s) is a transfer function of the high-pass filter.

[0010] In a non-limiting and exemplary embodiment, a motor module of the present disclosure comprises a motor and the control device described above.

[0011] In a non-limiting and exemplary embodiment, an electric power steering device of the present disclosure comprises the motor module described above.

[0012] In a non-limiting and exemplary embodiment, a control method of the present disclosure is a computer-implemented method for an electric power steering device with a motor that controls the motor, wherein the method comprises the following step: generating a correction torque based on an output from a control target and correcting an input to the control target with the correction torque using a model-following control that constrains a transfer function of the control target, which is the motor, to a target model in a frequency band in which a gain in a gain characteristic of Q(s)·HPF(s) is 1, wherein the model-following control comprises a high-pass filter with a first cutoff frequency and a low-pass filter with a second cutoff frequency that is greater than the first cutoff frequency, wherein Q(s) is a transfer function of the low-pass filter and HPF(s) is a transfer function of the high-pass filter.

[0013] According to an exemplary embodiment of the present disclosure, an engine control device, an engine module comprising the control device, an electric power steering device comprising the engine module and an engine control method are provided which is able to improve steering feel for the driver by applying model following control and / or friction compensation control to the torque control.

[0014] Preferred embodiments of the present invention are described in more detail below with reference to the accompanying drawings. These show: Fig. 1 a diagram schematically illustrating a configuration example of an electric power steering device according to an embodiment of the present invention; Fig. 2 a block diagram representing a typical example of a configuration of a control device according to the embodiment of the present disclosure; Fig. 3 a functional block diagram representing a function of a processor for controlling a motor according to the embodiment of the present disclosure; Fig. 4 a function block diagram that represents a configuration example of a model sequence control in the first implementation example; Fig. 5 a graph that shows a profit characteristic T(s) of Q(s)·HPF(s) and a profit characteristic of an inverse of a modeling error Δ(s) between a planned and a target model P n (s) represents; Fig. 6 a graph representing a profit diagram of a transfer function C(s) of a phase compensator in a torque control; Fig. 7 a graph representing a gain diagram of a transfer function HPF(s) of a high-pass filter; Fig. 8 a graph representing a profit diagram of a target model P n (s) represents; Fig. 9 a graph showing measurement results of a steering angle and a torsional torque in a case where model following control is not applied; Fig. 10 a graph showing measurement results of a steering angle and a torsional torque in a case where model following control is applied; Fig. 11 a graph that represents measurement results of a temporal change of a steering angle both in a case where model following control is not applied and in a case where model following control is applied; Fig. 12 a function block diagram that represents a configuration example of a model sequence control in the second implementation example; Fig. 13 a graph showing simulation results of a steering angle and steering torque both in a case where friction compensation control is not applied and in a case where friction compensation control is applied; Fig. 14 a graph showing simulation results of a steering angle and steering torque both in a case where the conventional friction compensation control is applied and in a case where the friction compensation control is applied according to the second implementation example.

[0015] With reference to the following drawings, exemplary embodiments of a motor control device attached to an electric power steering device of the present disclosure, a motor control method, a motor module comprising the control device, and an electric power steering device comprising the motor module are described in more detail. However, unnecessarily detailed descriptions may be omitted. For example, detailed descriptions of well-known items and duplicate descriptions of essentially the same configuration may be omitted. This is to avoid the following description becoming more cluttered than necessary and to facilitate understanding by a person skilled in the art.

[0016] The following embodiments are merely examples, and a motor control device attached to the electric power steering device according to the present disclosure, and a motor control method, are not limited to the following embodiments. For example, the numerical values, steps, sequence of steps, and the like shown in the following embodiments are merely illustrative, and various modifications can be made unless some technical inconsistency arises. The embodiments or examples described below are merely examples, and various combinations are possible as long as no technical contradiction arises. 1. Configuration of the electric power steering device 1000

[0017] Fig. Figure 1 schematically represents a configuration example of an electric power steering device 1000 according to the embodiment of the present disclosure.

[0018] The electric power steering device 1000 (hereinafter referred to as "EPS") comprises a steering system 520 and an assist torque mechanism 540 that generates an assist torque. The EPS 1000 generates the assist torque to support the steering torque of the steering system, which is generated when a driver operates a steering wheel. The assist torque reduces the operating load for the driver.

[0019] The steering system 520 includes, for example, a steering wheel 521, a steering shaft 522, universal joints 523A and 523B, a pivot shaft 524, a rack and pinion mechanism 525, a rack and pinion shaft 526, a left and a right ball joint 522A and 522B, tie rods 527A and 527B, joints 528A and 528B and a left and a right steered wheel 529A and 529B.

[0020] The support torque mechanism 540 includes, for example, a steering torque sensor 541, a steering angle sensor 542, an automotive electronic control unit (ECU) 100, a motor 543, a delay gear 544, an inverter 544, and a torsion bar 546. The steering torque sensor 541 detects steering torque in the steering system 520 by sensing the torsional forces of the torsion bar 546. The steering angle sensor 542 detects the steering angle of the steering wheel. Furthermore, the steering torque can be an estimated value derived from a calculation and not a value from the steering torque sensor. The steering angle can also be calculated based on the output value of the angle sensor.

[0021] The ECU 100 generates a motor drive signal based on the sensing signals acquired by the steering torque sensor 541, the steering angle sensor 542, a vehicle speed sensor (not shown) attached to a vehicle, and the like, to output the motor drive signal to the inverter 545. For example, according to the motor drive signal, the inverter 545 converts DC power into three-phase AC power with U-phase, V-phase, and W-phase pseudo-sine waves and supplies the power to the motor 543. The motor 543 is, for example, a surface permanent magnet synchronous motor (SPMSM) or a switched reluctance motor (SRM), and the three-phase AC power is supplied to it to generate an assist torque corresponding to the steering torque. The motor 543 transmits the generated support torque to the steering system 520 via the delay gear 544.Hereinafter, the ECU 100 will be referred to as control device 100 for the EPS.

[0022] The control unit 100 and the motor are modular and are manufactured and sold as a motor module. The motor module comprises the motor and the control unit 100 and is used accordingly for the EPS. Alternatively, the control unit 100 can be manufactured and sold independently of the motor as a control device for controlling the EPS. 2. Configuration example of the control device 100

[0023] Fig. Figure 2 represents a typical example of the configuration of the control device 100 according to the embodiment of the present disclosure. The control device 100 comprises, for example, a power supply circuit 111, an angle sensor 112, an input circuit 113, a communication interface 114, a drive circuit 115, a ROM 116, and a processor 200. The control device 100 can be implemented as a printed circuit board (PCB) on which these electronic components are implemented. The control device 100 is used to control a motor of an electric power steering device, which includes the motor.

[0024] A vehicle speed sensor 300, the steering torque sensor 541 and the steering angle sensor 542, which are attached to the vehicle, are connected to the processor 200 in a communication-capable manner and the vehicle speed, steering torque and steering angle are transmitted from the vehicle speed sensor 300, the steering torque sensor 541 and the steering angle sensor 542 respectively to the processor 200.

[0025] The control device 100 is electrically connected to the inverter 545 (see Fig. 1) The control device 100 controls switching operations of a plurality of switching elements (for example, MOSFETs) contained in the inverter 545. More precisely, the control device 100 generates a control signal (hereinafter referred to as the "gate control signal") to control the switching operations of the respective switching elements in order to output the gate control signal to the inverter 545.

[0026] The control device 100 generates a torque command value based on the steering torque or the like and controls the torque and rotational speed of the motor 543, for example, by vector control. The control device 100 can perform not only vector control but also other closed-loop control operations. The rotational speed is expressed by the number of revolutions (rpm) at which a rotor rotates per unit of time (for example, one minute) or the number of revolutions (rpm) at which the rotor rotates per unit of time (for example, one second). Vector control is a method in which the current flowing through the motor is separated into a current component that contributes to generating torque and a current component that contributes to generating magnetic flux, and the current components are orthogonal to each other and controlled independently.

[0027] The power supply circuit 111 is connected to an external power source (not shown) and generates the DC voltage required for each block in the circuit. The DC voltage to be generated is, for example, 3 V or 5 V.

[0028] The angle sensor 112 is, for example, a rotary encoder or a Hall-effect IC. Alternatively, the angle sensor 112 is also implemented by a combination of an MR sensor with a magnetoresistive (MR) element and a sensor magnet. The angle sensor 112 detects a rotation angle of the rotor in order to output the rotation angle to the processor 200. The control device 100 can include a velocity sensor and an acceleration sensor, which detect the rotational speed and acceleration of the motor instead of the angle sensor 112. The processor 200 can calculate the angular velocity ω [rad / s] based on the electrical angle θ. m calculate the engine.

[0029] The input circuit 113 receives a motor current value (hereinafter referred to as an "actual current value") detected by a current sensor (not shown), converts a level of the actual current value into an input level for the processor 200 as needed, and outputs the actual current value to the processor 200. A typical example of the input circuit 113 is an analog-to-digital conversion circuit.

[0030] The processor 20 is an integrated semiconductor circuit, also known as a central processing unit (CPU) or a microprocessor. The processor 200 sequentially executes a computer program stored in ROM 116, describing an instruction set for controlling the motor drive and performing the desired processing. Additionally or instead of the processor 200, the control device 100 includes a field-programmable gate array (FPGA), a graphics processing unit (GPU), an application-specific integrated circuit (ASIC), or an application-specific standard product (ASSP) to which a CPU is attached, or a combination of two or more circuits selected from these.The processor 200 sets a current instruction value according to the actual current value, the rotation angle of the rotor and the like, generates a pulse width modulation (PWM) signal and outputs the PWM signal to the drive circuit 115.

[0031] The communication interface 114 is an input / output interface configured to send and receive data in accordance with, for example, a vehicle's internal control area network (CAN).

[0032] The drive circuit 115 is typically a gate driver (or a pre-driver). The drive circuit 115 generates a gate control signal according to the PWM signal and outputs the gate control signal to the gates of the majority of switching elements contained in the inverter 545. There is one case where a gate driver is not necessarily required, for example, if the drive target is a motor that can be driven at low voltage. In this case, the processor 200 can perform the function of the gate driver.

[0033] ROM 116 is electrically connected to processor 200. ROM 116 is writable memory (for example, a PROM), rewritable memory (for example, flash memory or an EEPROM), or, for example, read-only memory. ROM 116 stores a control program that includes an instruction set to instruct processor 200 to control a motor drive. For example, at startup, the control program is temporarily extended into RAM (not shown).

[0034] Fig. Figure 3 represents functional blocks of the processor 200 for controlling the motor according to the embodiment of the present disclosure. In the illustrated implementation example, the processor 200, which is a computer, sequentially performs processing (or tasks) necessary for controlling the motor by using a torque controller, a model sequential controller, a subtractor, and an adder.

[0035] Each functional block is implemented in the processor 200 as software (or firmware) and / or hardware. The processing of each functional block is typically described in a computer program in units of software modules and stored in the ROM 116. In a case where an FPGA or the like is used, all or some of the functional blocks may be implemented as hardware accelerators. The motor control method according to the embodiment of the present disclosure is implemented in a computer and can be implemented by causing the computer to perform a desired operation.

[0036] The control device 100 comprises a torque controller 210, a model sequencing controller 230, a subtractor AD1, and an adder AD2. In other words, functions corresponding to the torque controller 210, the model sequencing controller 230, the subtractor AD1, and the adder AD2 are implemented in the processor 200.

[0037] The torque control 210 operates based on a steering torque T h and sends an input to a control target 220, which is a motor. For example, the steering torque T h The torque detected by the steering torque sensor 541 is input into the torque control unit 210. The torque control unit 210 generates a target motor torque (or a torque command value) T. ref by applying phase compensation to the steering torque T h , if the steering frequency or steering speed is within a predetermined range, and specifies the target engine torque T refinto the tax target 220.

[0038] The in Fig. The torque control unit 210 shown in Figure 3 comprises a basic support calculation unit 211 and a phase compensator 212.

[0039] The basic support calculation unit 211 records the steering torque T h and the vehicle speed. The basic support calculation unit 211 generates a basic support torque based on the steering torque T. h and the vehicle speed. For example, the basic support calculation unit 211 may include a lookup table (LUT) that provides a correspondence between the steering torque T h , defined by the vehicle speed and the basic support torque. The basic support calculation unit 211 can determine the basic support torque using a correspondence relationship based on the steering torque T. hand the vehicle speed with reference to the LUT. Furthermore, the basic support calculation unit 211 can determine the basic support gain based on the slope, which is determined by the ratio of the change in the basic support torque to the fluctuation in the steering torque T. h is defined.

[0040] In the embodiment of the present disclosure, the phase compensator 212 adjusts the assistance gain within a range of steering frequency when the driver operates the steering wheel and compensates for the stiffness of the torsion bar. In the embodiment of the present disclosure, an example of the predetermined range is 5 Hz or less. The phase compensator 212 can, for example, apply first-order phase compensation to the steering torque (torsional torque) when the steering frequency is 5 Hz or less. The first-order phase compensation is expressed, for example, by a transfer function of the mathematical expression of Equation 1. C(s)=12πf1s+112πf2s+1 where s is a Laplace transformer, f1 is the frequency (Hz) of the zero point of the transfer function, and f2 is the frequency (Hz) of the pole of the transfer function. A graph in which the gain (or loop gain) is set as the vertical axis and the logarithm of the frequency is set as the horizontal axis is called a gain diagram. In the gain diagram, the zero point represents the intersection of the gain curve and the horizontal axis, indicating 0 dB, and the pole represents the maximum point of the gain curve. By setting the pole frequency so that it is higher than the zero point frequency, phase advance compensation can be applied, for example. The greater the distance between the frequencies, the greater the magnitude of the phase advance.

[0041] The phase compensator 212 generates a target motor torque T refbased on the basic support torque and the basic support gain output from the basic support calculation unit 211. For example, the phase compensator 212 can be a stabilization compensator and can apply stabilization phase compensation to the basic support torque. The phase compensator 212 can have a second-order or higher transfer function whose frequency characteristic is variable according to the basic support gain. The second-order or higher transfer function is expressed using a response sensitivity parameter ω and an attenuation parameter ζ. The second-order or higher transfer function can be expressed, for example, by the mathematical expression of Equation 2. By setting the order of the transfer function to two, attenuation can be added to the transfer function characteristic.A phase characteristic can be adjusted by changing the damping. C(s)=s2+2ς1ω1s+ω12s2+2ς2ω2s+ω22(ω22ω12) where s is a Laplace transformer, ω1 is a zero-point frequency, ω2 is a pole frequency, ζ1 is a zero-point attenuation, and ζ2 is a pole attenuation. The pole frequency ω2 is lower than the zero-point frequency ω1.

[0042] The model follower 230 is configured to estimate the disturbance torque based on the angular velocity ω (MR angular velocity) of the motor, which is the output of the control target 220, calculate the estimated disturbance torque, and feed the estimated disturbance torque back to the input of the control target 220. The torque fed by the model follower 230 to the input of the control target 220 corresponds to a "correction torque" for correcting the input of the control target 220. The model follower 230 generates the correction torque based on the output of the control target 220. An example of the model follower 230 is a model follower configured to perform model follower control. A specific configuration of the model follower 230 is described in more detail below.

[0043] The subtractor AD1 subtracts the estimated disturbance torque output by the model sequence controller 230 from the target motor torque T. ref The output from subtractor AD1 is fed into adder AD2 and model sequence control 230. Adder AD2 adds the disturbance torque T. dto the output of subtractor AD1 to output the result to control target 220. Here, examples of disturbance in the embodiment of the present disclosure include friction caused by a mechanism such as a motor or a delay gear, torque, torque ripple or rattle, self-adjusting torque, or disturbance that may occur when the vehicle is traveling on an unpaved, bumpy road or a gravel road. Here, self-adjusting torque is a torque that acts in a direction in which the steering wheel returns due to the elasticity of the tire, which is rotated when the steering wheel is turned. First implementation example

[0044] The model-following control system has an inverse plant model, a high-pass filter, and a low-pass filter (or Q-filter). The model-following control system is configured so that the transfer function P(s) of the control target in a frequency band where the gain in a gain characteristic of Q(s)·HPF(s) is 1 corresponds to the target model P. n (s) is restricted, where Q(s) is a transfer function of the low-pass filter and HPF(s) is a transfer function of the high-pass filter. It should be noted that in the present description, "the transfer function of the control target is restricted to the target model" means that, for example, the control target is controlled, so that the transfer function of the control target appears as the transfer function of the target model when considering the input / output relationship.

[0045] Fig. Figure 4 presents a configuration example of a model tracking controller 230A in the first implementation example. The model tracking controller 230A comprises an inverse control target model 231, a low-pass filter 232, a high-pass filter 233, and a subtractor SU1. The high-pass filter 233 has a first cutoff frequency, and the low-pass filter 232 has a second cutoff frequency.

[0046] The angular velocity ω of the motor is input into the inverse control target model 231. The subtractor SU1 subtracts the output of the subtractor AD1 from the output of the inverse control target model 231 to obtain an estimated disturbance torque ^T. d to generate. The estimated disturbance torque ^T dThe signal is subjected to a filtering process by the low-pass filter 232 and the high-pass filter 233, which are connected in series in that order, and is fed into the subtractor AD1. As described above, the model sequence controller 230A applies the estimated disturbance torque ^T. d back to input in control target 220. It should be noted that “^T d “T d with a "hat" means, as depicted in Fig. 4 and Fig. 12.

[0047] The model-following controller 230A performs model-following control, which means a feedback loop using the angular velocity ω of the motor, which is the control target 220, for an outer current control loop. In the first implementation example, the torque ripple as a function of the angular velocity ω can be compensated by the feedback loop formed by the model-following controller 230A. The angular velocity ω signal used for control can be corrected for any type of motor, and the accuracy of the angular velocity ω signal can be improved compared to the current signal, etc. As a result, torque ripple compensation can be applied to the torque control with high accuracy.

[0048] The 230A model sequence control is structurally similar to a conventional disturbance estimator (or disturbance observer), but has different steps and effects. The conventional disturbance estimator estimates the disturbance torque by selecting the inverse plant model to a value close to the plant model, pre-setting the disturbance torque and reducing the influence of the disturbance. The frequency band to be compensated is a low frequency of 4 Hz or less, which can be generated by the vehicle's behavior.

[0049] The model sequential control according to the embodiments of this disclosure utilizes the effect of a feedback loop, which restricts the system model to the target model defined in the inverse system model. A frequency band to be compensated is approximately 4 Hz to 150 Hz, which differs from the frequency band of a conventional disturbance estimation device. For example, if the inverse system model is defined such that there is no torque ripple, the system model is restricted by the model sequential control to the characteristic without torque ripple, and consequently, the torque ripple can be reduced by applying torque ripple compensation. Furthermore, by constructing an inertial or viscosity model and restricting the system model to this model, a reduction in the inertia or viscosity of the system model can be achieved.By performing model sequence control, for example, the compensation of lost torque or the compensation of motor inertia is carried out in addition to the compensation of the motor's torque ripple.

[0050] In the present description, the control target 220, the target model (or plant model) used to constrain the control target 220, the inverse control target model 230, defined by an inverse plant model of the plant model, the transfer function of the low-pass filter 232, and the transfer function of the high-pass filter 230 are described as P(s), P n (s), P n -1 (s), Q(s) or HPF(s).

[0051] The investment model (target model) is expressed by the mathematical expression of Equation 3, and the inverse investment model is expressed by the mathematical expression of Equation 4. By adjusting J accordingly. mn and B mnA desired frequency characteristic can be specified at P(s) of the control target 220. In the present embodiment, the system model (target model) is a model of a single-inertia system. 1Jmns+Bmn Jmns+Bmn

[0052] A complementary sensitivity function of the inner loop, configured by the model-following control, is defined as T(s), and a modeling error of the plant model is defined as Δ(s). T(s) is expressed by Q(s)·HPF(s), and the relationship shown in Equation 5 is established with respect to Δ(s). The robust stability of the model-following control is ensured if the small gain theorem, expressed by the mathematical equation in Equation 6, holds between T(s) and Δ(s). To suppress a disturbance, it is sufficient for T(s) = 1, but for robust stability, it is necessary to satisfy the mathematical expression of Equation 6. As is clear from this, disturbance suppression and robust stability are incompatible. P(s)=1Jmns+Bmn(1+Δ(s)) |T(jω)|<1|Δ(jω)| |T(jω)Δ(jω)|<1, ∀s=jω

[0053] Fig. Figure 5 shows a gain diagram of the transfer function of the entire steering system. In the gain diagram, the horizontal axis represents the frequency [Hz] and the vertical axis the gain [dB]. To achieve interference suppression across the frequency band, the first embodiment divides the frequency band into a region I, where interference suppression is necessary and T(s) = 1, and a region II, where T(s) is reduced to ensure robust stability. In region II, 1 / Δ(s) > T(s).

[0054] The gain characteristic of the transfer function of the entire steering system, for example, has peaks around 20 Hz and around 50 Hz, and the modeling error appears at one of the two peaks around 50 Hz. That is, Δ(s) has a peak around 50 Hz, and 1 / Δ(s), as shown in Fig. 5 has a low point around 50 Hz. As a gain characteristic adjustment method, there is the adjustment of 1 / Δ(s) and the setting of a breakpoint of T(s). The adjustment of 1 / Δ(s) is carried out by setting J mn and B mn The adjustment of the system model and the setting of the cutoff point of T(s) is carried out by adjusting the second cutoff frequency of the low-pass filter 232. Furthermore, the sensitivity to disturbances can be adjusted by the amount of steering assistance, the steering speed, or the vehicle speed. In a case where the frequency of the low point of the modeling error is close to the frequency of the boundary between regions I and II, a procedure to increase the magnitude of the low-pass filter 232 is often used as a countermeasure to significantly reduce T(s) in region I, where disturbance suppression is necessary.

[0055] The control device 100 performs torque control on a low-frequency torque signal and applies control such that the angular velocity ω is approximately ω ≈ 0 in the event of a high-frequency disturbance, thereby stabilizing the steering and preventing the steering wheel from becoming uncontrollable. To achieve this, the control device 100 reduces the high-frequency gain of the torque control using torque control 210 and limits the control target P(s) to the characteristic at which the high-frequency gain decreases using model following control 230A. The reason for performing the latter process is to prevent the control target 220 from reacting to a disturbance, such as T. d , shown in Fig. 4, if the fault is entered into control target 220.

[0056] Fig. Figure 6 shows a gain diagram of the transfer function C(s) of the phase compensator 212 in the torque control 210. Fig. Figure 7 shows a gain diagram of the transfer function HPF(s) of the high-pass filter 233. Fig. Figure 8 shows a profit diagram of the target model P n (s). In the gain diagram, the horizontal axis represents the frequency [Hz] and the vertical axis represents the gain [dB]. For example, if the phase compensator 212, which affects the gain characteristic of the in Fig. When the transfer function C(s) shown in section 6 is applied, the high-frequency gain can be found in the gain characteristic of the target model P. n (s) are reduced, as in Fig. Figure 8 is shown. The cutoff frequency fc in the gain diagram of the transfer function C(s) is, for example, 2 Hz or more and 10 Hz or less, and the cutoff frequency fc in the gain diagram of P is n(s) is, for example, 2 Hz or more and 20 Hz or less.

[0057] The model sequence control 230A is configured such that the transfer function P(s) of the control target 220 is limited to the target model P n (s) in the frequency band where the gain in the gain characteristic of Q(s)·HPF(s) is 1. The inverse investment model P n -1 (s) is designed to yield an inverse characteristic for which a restriction is desired and to exploit the gain characteristics of Q(s)·HPF(s). By appropriately designing J mn and B mn of the investment model, as it is in Fig. As shown in section 8, profit characteristics of the target model P can be determined. n(s), whose gain decreases in a high-frequency region, are obtained. The frequency of the boundary between Region I and Region II (the lower limit of the frequency range defining Region I) is the maximum frequency that can be input by the driver and is generally about 2 Hz to 10 Hz. This frequency depends on the first cutoff frequency of the high-pass filter 233. Therefore, the lower cutoff frequency of the effective range of the model tracking control is determined by setting the first cutoff frequency of the high-pass filter 233 so that it does not interfere with the torque control.

[0058] The low-pass filter 232 and the high-pass filter 233 are coupled in series. The low-pass filter 232 can comprise a multi-stage TPF. That is, Q(s) can be expressed as a transfer function of the n-stage TPF (n is 1 or more). The second cutoff frequency is higher than the first cutoff frequency. The first cutoff frequency is, for example, 2 Hz or more and 10 Hz or less, and preferably 5 Hz or more and 7 Hz or less. The second cutoff frequency is, for example, 3 Hz or more, and preferably 50 Hz or less. The upper limit of the second cutoff frequency can be set to about 140 Hz to 200 Hz. The cutoff frequency fc of the gain characteristic of the target model P n (s), in Fig. Figure 8 shows that it depends on the first cutoff frequency and the second cutoff frequency and is, for example, 2 Hz or more and 20 Hz or less.

[0059] The inventors of the present invention confirm the effect obtained by applying the model sequence control according to the embodiment of the present disclosure by performing an actual vehicle measurement. During the actual vehicle measurement, the effect of reducing torque ripple and generating the uncontrollable steering wheel by applying the model sequence control to the torque control was measured. Here, generating the uncontrollable steering wheel means that the steering wheel swivels left and right when the vehicle crosses a step in a state where the hands are not on the steering wheel.

[0060] Fig. Figure 9 presents measurement results of the steering angle and the torsional torque in a case where model following control is not applied. Fig. Figure 10 presents measurement results of the steering angle and torsional torque in a case where model following control is applied. In the graph, the horizontal axis represents the steering angle [degrees] and the vertical axis represents the torsional torque [Nm]. The graph shows signal waveforms measured when steering is performed at an angular velocity of 180 [degrees / second] from end to end (from a state where the steering wheel is fully turned to the left to a state where the steering wheel is fully turned to the right, or vice versa).

[0061] When the section enclosed by the alternating long and short dashed line of the graph is enlarged, it was found that torque ripple can be suppressed when model following control is applied, compared to when model following control is not. More precisely, it was found that the magnitude of the torsional torque fluctuation is reduced by approximately 0.1 Nm.

[0062] Fig. Figure 11 presents measurement results of the change in steering angle over time, both when model following control is not applied and when it is applied. In the graph, the horizontal axis represents time [seconds] and the vertical axis represents steering angle [degrees]. The time region when the vehicle has driven over the step is indicated by a dashed rectangle. It was found that by applying model following control to the torque control, the change in steering angle when the vehicle drives over the step is suppressed, and the generation of uncontrollable steering wheel movement can be correspondingly reduced.

[0063] According to the first implementation example, the high-frequency component of the disturbance can be reduced by applying model following control to the torque control. As a result, it is possible to appropriately reduce the torque ripple that can occur when the vehicle is steered and the generation of uncontrollable steering that can occur when the vehicle drives over the step. Second implementation example

[0064] Next, the model sequence control will be implemented according to the second implementation example with reference to Fig. 12, Fig. 13 to Fig. The model sequencing control according to the second implementation example differs from the model sequencing control according to the first implementation example in that the latter includes a friction compensation calculation device. The main differences from the model sequencing control according to the first implementation example are described below.

[0065] Since the disturbance estimated by the model-following control includes friction from a mechanism, such as a motor and a deceleration drive, the model-following control, as described in the second implementation example, is configured to extract a friction component from the estimated disturbance torque and apply friction compensation to the estimated disturbance torque. Friction compensation is used, for example, for motor friction, deceleration drive friction, or a right / left differential in the deceleration drive friction.

[0066] When conventional friction compensation control is applied when the motor's angular velocity ω is close to zero, changes in the friction compensation torque (Nm) relative to the motor's angular velocity ω must be gradual to prevent flutter. Consequently, in some cases, highly accurate friction compensation control cannot be achieved. To overcome this problem, the inventor's investigations suggest that it is desirable to estimate and compensate for friction sequentially.

[0067] The model following control according to the second implementation example is configured to feed the disturbance compensation torque back to the input in the control target. More precisely, the model following control includes a high-pass filter that removes a low-frequency component from the estimated disturbance torque, a friction compensation calculation device that is coupled in parallel to the high-pass filter and applies friction compensation to the estimated disturbance torque to calculate an estimated value of the mechanical friction torque, and an adder that adds the estimated value of the friction torque to the estimated disturbance torque from which the low-frequency component was removed by the high-pass filter to generate a disturbance compensation torque.In the second implementation example, the estimated disturbance torque corresponds to a "first correction torque" and the disturbance compensation torque corresponds to a "second correction torque".

[0068] Fig. Figure 12 presents a configuration example of a model sequencing controller 230B in the second implementation example. The model sequencing controller 230B is configured to perform model sequencing in the same way as the model sequencing controller 230A according to the first implementation example. However, the function of the model sequencing controller is not essential.

[0069] The model sequence control 230B includes a friction compensation calculation device 250. The friction compensation calculation device 250 is coupled in parallel to the high-pass filter 233 and calculates an estimated value of the mechanical friction torque by applying friction compensation to the estimated disturbance torque ^T. dThe friction compensation calculation device 250 comprises a subtractor 251, a limiter 252, and a gain adjuster 253. The subtractor 251 subtracts the output value from the high-pass filter 233 from the output value from the low-pass filter 232. The limiter 252 limits the output value from the subtractor 251. If the input value exceeds the upper limit, the upper limit threshold, or the lower limit threshold, the limiter 252 truncates the input value to the upper limit threshold or the lower limit threshold, respectively.

[0070] Profit adjuster 253 multiplies the output value of limiter 252 by profit K. The maximum value of profit K for profit adjuster 253 is determined under the condition that the transfer function of control target 220 is restricted to the target model. For example, the maximum value of profit K is set to approximately 1 to 1.2.

[0071] The estimated disturbance torque ^T d This includes mechanical friction. When estimating the disturbance, the friction is first estimated along the transmission path of the motor's output torque, and then the torque acting on the motor, such as the self-adjusting torque, is estimated. Therefore, the Friction Compensation Calculation Unit 250 calculates a value corresponding to the frictional torque in the disturbance, which is estimated first, as an estimated value of the frictional torque. Since suitable friction is required for the EPS, it is generally possible to achieve highly accurate friction compensation while maintaining a suitable frictional force by setting a value that is smaller than the frictional force actually acting on an estimated value of the frictional torque.

[0072] To apply friction compensation to the estimated disturbance torque used for model tracking control, it is necessary to consider the stability condition of the model tracking control. This condition means that the gain in the gain characteristic of the transfer function of the friction compensation calculation device 250, restricted to the characteristic where stability is considered, does not exceed 1, based on the small gain theorem described above. This is derived from the design condition of the low-pass filter 232. In the second implementation example, the subtractor 251 is placed one stage before the limiter 252, so that the value of the friction compensation gain, i.e., the gain K, is set to a maximum of 1 to constantly satisfy this condition, and the gain in the gain characteristic is set to 1 under this condition, and the subtraction processing is applied.In other words, the friction compensation calculation device 250 behaves as a low-pass filter with a transfer function of 1-HPF(s).

[0073] The estimated disturbance torque ^T d' includes a low-frequency component ^T d1 , a medium frequency component ^T d2 and a high-frequency component ^T d3 The low-pass filter 232 removes the high-frequency component ^T d3 of the estimated disturbance torque ^T d and the high-pass filter 233 further removes the low-frequency component ^T d1 of the estimated disturbance torque ^T d As described above, friction compensation is only effective for the mid-frequency component ^T. d2 of the estimated disturbance torque in the range from the first cutoff frequency of the high-pass filter 233 to the second cutoff frequency of the low-pass filter 232.

[0074] Since the assumed friction contained in the disturbance is a low-frequency component of the disturbance, the low-frequency component ^T d1 It is not subjected to any friction compensation according to the filter process described above. By coupling the friction compensation calculation device 250 in parallel to the high-pass filter 233, the low-frequency component ^T is therefore reduced. d1 the disturbance that was subjected to the filtering process by the high-pass filter 233 and is no longer compensated, again the estimated disturbance torque ^T d added, thereby realizing friction compensation. More precisely, the friction compensation calculation device 250 adds a value obtained by multiplying the low-frequency component ^T. d1 with the gain K, to the medium frequency component ^T d2 , to generate the disturbance compensation torque. It should be noted that “^T d1 “T d1means with the "hat" that is in Fig. 12 is shown, “^T d2 “ means, T d2 with the "hat" that is in Fig. 12 is shown and “^T d3 “ means T d3 with the "hat" that is in Fig. 12 is shown.

[0075] A vehicle equipped with EPS is capable of operating in both automatic and manual drive modes. In this case, the gain K of gain adjuster 253 can be switched according to the drive mode. The greater the gain K, the greater the degree of friction reduction. The gain K set in automatic drive mode is preferably greater than the gain K set in manual drive mode. Consequently, it is possible to apply optimal friction compensation to an automatic drive mode, where friction reduction is more likely to be required.

[0076] The model sequence control 230B also includes an adder AD3. The adder AD3 adds the output value from the gain adjuster to the output value from the high-pass filter 233. The output of the adder AD3 is fed back to the input of the control target 220 as a disturbance compensation torque.

[0077] An auxiliary device has been developed that detects a lane marking, such as a white or yellow line, while driving on a highway and assists the automatic driving of a vehicle following the line. It is known that if a right / left differential occurs in the friction of a deceleration gear in a vehicle equipped with EPS and an auxiliary device, the control of the auxiliary device, which ensures that the vehicle travels straight along the center of a lane, can be impaired. According to the friction compensation control of the embodiment described in the present disclosure, even in a case where there is a right / left differential in the friction of the deceleration gear, it is possible to sequentially calculate an estimated value of the friction torque, thus solving the problem described above.It should be noted that the angular velocity ω of the motor, which is the output of the plant model, includes information about a right / left difference in the friction of the deceleration gear.

[0078] The inventors of the present invention confirm, through simulation, the effect obtained by applying friction compensation control via the profit setting. The effect of reducing friction through friction compensation control was measured by simulation.

[0079] Fig. Figure 13 presents the simulation results for the steering angle and steering torque in both cases where friction compensation control is not applied and where it is. In the graph, the horizontal axis represents the steering angle [degrees] and the vertical axis represents the torque [Nm]. A graph represented by a dashed line shows the signal when friction compensation control is not applied, and a graph represented by a solid line shows the signal when friction compensation control is applied. An arrow in the graph indicates the width of the steering torque, and this width corresponds to the magnitude of the friction. It was found that friction can be adequately reduced by applying friction compensation control.

[0080] Fig.Figure 14 presents the simulation results for the steering angle and steering torque both when conventional friction compensation control is applied and when friction compensation control is applied via gain setting. In the graph, the horizontal axis represents the steering angle [degrees] and the vertical axis represents the steering torque [Nm]. A graph represented by a dashed line shows the signal profile when conventional friction compensation control is applied, and a graph represented by a solid line shows the signal profile when friction compensation control is applied via gain setting.According to the conventional friction compensation control as described above, when the angular velocity ω of the motor is close to zero, the change in the friction compensation torque [Nm] with respect to the angular velocity ω of the motor must be gradual to prevent flutter. Therefore, a spike was observed in the steering torque when the steering wheel was turned (see the section enclosed by the dashed circle in the figure). On the other hand, when the friction compensation control was applied using gain adjustment, no spike was observed, and it was found that the friction was adequately reduced.

[0081] According to the second implementation example, by further applying friction compensation control through gain adjustment to the torque control, it is possible to appropriately reduce friction while reducing a high-frequency component of the disturbance. Third implementation example

[0082] In the third implementation example, the control target comprises a steering wheel 521, universal joints 523A and 523B, a rotating shaft 524, a torsion bar 546, a motor 543, and a delay gear 544. Since the control target in the third implementation example includes sections that can rotate relative to each other via the torsion bar 546, the motion of the control target cannot be described solely by a simple equation of motion for a one-inertia system. The control target in the third implementation example switches between the one-inertia system and the two-inertia system depending on the force with which the driver grips the steering wheel 521. The more forcefully the driver grips the steering wheel 521, the closer the control target is to the one-inertia system. The less forcefully the driver grips the steering wheel, the closer the control target is to the two-inertia system.In the third implementation example, an angular velocity corresponding to the angular velocity of the deceleration gear 544 is entered as an output of the control target into the model following control.

[0083] In the third implementation example, the system model (target model) is a model with frequency characteristics between the one-inertia system and the two-inertia system. The transfer function P n (s) of the plant model (target model) in the third implementation example is expressed by the mathematical expression of equation 7 and the transfer function P n -1 (s) of the inverse investment model is expressed by the mathematical expression of equation 8. 1JSTGns+BSTGns2+2ς1nω1ns+ω1n2s2+2ς2nω2ns+ω2n2 1JSTGns+BSTGn(s2+2ς2nω2ns+ω2n2s2+2ς1nω1ns+ω1n2)

[0084] In the mathematical expression of equation 7 and the mathematical expression of equation 8, s is a Laplace transform, J STGn is a parameter that represents the moment of inertia of the target model, B STGn ω is a parameter representing the viscous friction coefficient of the target model. 1n is the frequency of the zero point of the transfer function P n (s), ω 2n is the frequency of the pole of the transfer function P n (s), ζ 1n is the damping ratio at the zero point of the transfer function P n (s) and ζ 2n is the damping ratio at the pole of the transfer function P n (s).

[0085] In the third implementation example, the target model is a model with frequency characteristics between the one-inertia system and the two-inertia system. The mathematical expression of equation 7, which defines the transfer function P n(s) of the target model is an expression obtained by adding a damping term to an expression representing the two-inertia system. In the mathematical expression of Equation 7, the damping terms are 2ζ 1n ω 1n s and 2ζ 2n ω 2n The expression obtained by removing these damping terms from the mathematical expression of Equation 7 is an expression representing the two-inertia system. In the third implementation example, the degree of the transfer function P is n (s) of target model 3.

[0086] In the third implementation example, the target model is one that considers mechanical characteristics when a driver (steering person) steers the steering wheel 521. The control target approaches the one-inertia system when the driver grips the steering wheel 521 firmly and approaches the two-inertia system when the driver grips the steering wheel 521 loosely. Therefore, the transfer function P(s) of the control target in the third implementation example changes between the one-inertia system and the two-inertia system depending on how a force is transmitted from the driver's arm to the steering wheel 521. In the third implementation example, by setting the target model to a model with frequency characteristics between the one-inertia system and the two-inertia system, it is possible to prevent the modeling error Δ(s) between the transfer function P n(s) of the target model and the transfer function P(s) the control target becomes too large, regardless of the state of the control target between the one-inertia system and the two-inertia system. Therefore, the control target can be appropriately controlled using the target model, regardless of how the driver steers the steering wheel 521. As described above, in the third implementation example, the target model is a model that takes into account mechanical characteristics that the control target acquires through the way the driver grips the steering wheel 521. The control device 100 in the third implementation example can appropriately control the control target by having such a target model as an internal model. Other configurations of the third implementation example can be similar to those in the other implementation examples described above.

[0087] It should be noted that the control device of each implementation example described above includes, but is not limited to, a torque control that provides an input to a control target, which is a motor. The control device according to the present disclosure may also not include the torque control.

[0088] The embodiments of the present invention can be used for an engine control device for controlling an EPS that is attached to a vehicle. Reference sign 100 Electronic Control Unit (ECU) 200 processor 210 Torque control 211 Response sensitivity phase compensation unit 212 Phase compensator 220 Tax target 230, 230A, 230B Model sequence control 231 inverse tax target model 232 Low-pass filters 233 High-pass filters 250 Friction compensation calculation device 251 Subtractors 252 limiters 253 profit setters 1000 electric power steering device AD1 Subtractor AD2, AD3 Adder SU1 Subtractor

Claims

[1] Control device (100) used in an electric power steering device (1000) comprising a motor (543), wherein the control device (100) controls the motor (543), the control device (100) having the following features: a model sequence control (230) which generates a correction torque based on an output from a control target (220), which is the motor (543), and which corrects an input to the control target (220) with the correction torque, wherein the model sequence control (230) comprising a high-pass filter (233) with a first cutoff frequency and a low-pass filter (232) with a second cutoff frequency that is higher than the first cutoff frequency, wherein an estimated disturbance torque ^T d is subjected to a filtering process by the low-pass filter (232) and the high-pass filter (233) connected in series with it, characterized by , that the model following control (230) is configured such that a transfer function P(s) of the control target (220) is restricted to a target model in a frequency band in which a gain in a gain characteristic of Q(s)·HPF(s) is 1, where Q(s) is a transfer function of the low-pass filter and HPF(s) is a transfer function of the high-pass filter. [2] Control device (100) according to claim 1, characterized by that the first cutoff frequency is 2 Hz or more and 10 Hz or less. [3] Control device (100) according to claim 2, characterized by that the second cutoff frequency is 3 Hz or more. [4] Motor module which has the following features: an engine (543); and the control device (100) according to one of claims 1 to 3. [5] Electric power steering device (1000) comprising the motor module according to claim 4. [6] Computer-implemented method for controlling a motor of an electric power steering device (1000) comprising the motor (543), the method comprising the following steps: Generating a correction torque based on an output from a control target (220) and correcting an input to the control target (220) with the correction torque using a model following control (230) comprising a high-pass filter (233) with a first cutoff frequency and a low-pass filter (232) with a second cutoff frequency higher than the first cutoff frequency, wherein an estimated disturbance torque ^T d is subjected to a filtering process by the low-pass filter (232) and the high-pass filter (233) connected in series with it, characterized by , that using the model following control (230) a transfer function P(s) of the control target (220), which is the motor (543), is restricted to a target model in a frequency band in which a gain in a gain characteristic of Q(s)·HPF(s) is 1, where Q(s) is a transfer function of the low-pass filter and HPF(s) is a transfer function of the high-pass filter.

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