Input / Output Device and Steering Measurement Device

Abstract

An input / output device (3) comprises: an identification signal command unit (4) that outputs, to an electric power steering device (50) which adds auxiliary steering force to a steering provided to a vehicle, an identification signal for identifying a parameter of the electric power steering device or a command signal for instructing the electric power steering device to start outputting the identification signal; and a parameter identification unit (5) that identifies the parameter of the electric power steering device from a response of the electric power steering device to the identification signal, wherein the parameter identification unit identifies the parameter of the electric power steering device on the basis of responses to a first identification signal and a second identification signal which are output when the steering is in a prescribed rotation state, wherein the first identification signal is for identifying a linear parameter and the second identification signal is for identifying a non-linear parameter.

Description

Technical Field

[0001] The present disclosure relates to an input / output device and a steering measurement device.

Background Art

[0002] An electric power steering device includes a motor that generates a steering assist torque with respect to steering, and a control device that controls the motor, and adds a steering assist force to a steering mechanism of a vehicle such as an automobile. A steering measurement device is a device for performing a measurement test for identifying mechanical constants of such an electric power steering device.

[0003] The following Patent Document 1 discloses an example of a conventional steering measurement device. This steering measurement device applies a random number or a sine sweep-like excitation signal to an electric power steering device to vibrate the steering, and calculates mechanical constants such as inertia, viscosity, and rigidity of the electric power steering device based on the response obtained thereby.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] By the way, the steering measurement device disclosed in Patent Document 1 described above can identify only mechanical constants having a characteristic that a response signal with respect to an input signal is linear among the mechanical constants of the electric power steering device. Here, in the steering mechanism of the electric power steering device, there is a non-linear element in which a response signal with respect to an input signal has a non-linear characteristic. Examples of such a non-linear element include a friction element.

[0006] When evaluating the performance of an electric power steering device through in - vehicle analysis, a high - precision model of the electric power steering device is required. In the steering measurement device disclosed in Patent Document 1 described above, it is impossible to identify the friction element which is a non - linear element. For this reason, conventionally, there has been a problem that the accuracy of evaluation decreases due to the modeling error of the electric power steering device.

[0007] The present disclosure has been made in view of the above circumstances, and an object thereof is to provide an input - output device and a steering measurement device that can accurately identify not only linear parameters identified by conventional methods but also non - linear parameters not identified by conventional methods.

Means for Solving the Problems

[0008] In order to solve the above problems, an input - output device according to an aspect of the present disclosure outputs an identification signal for identifying parameters of an electric power steering device that adds a steering assist force to a steering provided in a vehicle, or an instruction signal for instructing the start of output of the identification signal to the electric power steering device, and a parameter identification unit that identifies parameters of the electric power steering device from a response of the electric power steering device to the identification signal. The parameter identification unit identifies parameters of the electric power steering device based on responses to a first identification signal for identifying linear parameters and a second identification signal for identifying non - linear parameters, which are output when the steering is in a predetermined rotation state.

[0009] Also, a steering measurement device according to an aspect of the present disclosure includes the above input / output device, and is connected to the input / output device via an in-vehicle communication network provided in the vehicle. Based on the first identification signal or the second identification signal, it controls a rotating machine provided in the electric power steering device to add a steering assist force to the steering, and outputs response data indicating the response of the electric power steering device to the first identification signal or the second identification signal to the input / output device via the in-vehicle communication network, and a control device.

Advantages of the Invention

[0010] According to the present disclosure, in addition to the linear parameters identified by the conventional method, non-linear parameters not identified by the conventional method can also be identified with high accuracy. As a result, the mechanical characteristics of the electric power steering device can be identified with high accuracy, and the accuracy of the bench analysis model for evaluating the characteristics of the electric power steering device can be improved.

Brief Description of the Drawings

[0011]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Embodiments for Carrying Out the Invention

[0012] Hereinafter, with reference to the drawings, an input / output device and a steering measurement device according to an embodiment of the present disclosure will be described in detail.

[0013] [Embodiment 1] FIG. 1 is a configuration diagram showing an input / output device and an electric power steering device according to Embodiment 1 of the present disclosure. As shown in FIG. 1, the input / output device 3 according to the present embodiment includes an identification signal command unit 4 and a parameter identification unit 5. The identification signal command unit 4 outputs an identification signal based on an identification start instruction of mechanical constants input from the outside. The parameter identification unit 5 identifies the mechanical constants of the electric power steering device 50 based on the response data of the electric power steering device 50 obtained as a response to the identification signal. Note that, as the hardware constituting the input / output device 3, for example, a computer such as a tablet computer or a notebook computer can be used. The details of the input / output device 3 will be described later.

[0014] The electric power steering device 50 includes a steering wheel 51, a steering shaft 53, a rack and pinion gear 54, a wheel 55, a tie rod 56, a knuckle arm 57, a torque detector 22, a rotation detector 23, a rotary machine 1, and a control device 2. The hardware configuration of the electric power steering device 50 is the same as that of a conventional electric power steering device and is mass-produced and mounted on a vehicle. However, the software installed in the control device 2 is partially different from the software installed in the existing control device. Specifically, the software installed in the control device 2 has an additional process for generating an identification signal for identifying the mechanical constants of the electric power steering device 50 with respect to the software installed in the existing control device. The details of this additional element will be described later.

[0015] The input / output device 3 and the electric power steering device 50 are connected by an in-vehicle communication network NW. The transmission of the identification signal from the input / output device 3 to the electric power steering device 50 is performed via the in-vehicle communication network NW. The in-vehicle communication network NW is a communication network that is mounted on a vehicle, connects between in-vehicle electrical components, and transmits and receives data. The in-vehicle communication network NW is normally mounted on mass-produced vehicles. The input / output device 3 and the control device 2 are connected using such an in-vehicle communication network NW. Here, the in-vehicle communication network NW includes types such as CAN (Controller Area Network) (registered trademark), FlexRay (registered trademark), Ethernet (registered trademark), etc. Depending on the type mounted on the vehicle, an in-vehicle communication network cable may be wired.

[0016] The steering measurement device 60 according to the present embodiment is composed of a control device 2 provided in the electric power steering device 50 and an input / output device 3. Hereinafter, first, the details of the electric power steering device 50 including the control device 2 will be described, and then, the details of the steering measurement device 60 (control device 2 and input / output device 3) will be described.

[0017] 〈Electric Power Steering Device〉 The steering wheel 51 is a so-called steering wheel and is operated by a vehicle driver (not shown) to give a steering angle to the steering wheel (wheel 55) of the vehicle. The steering shaft 53 is composed of an input shaft 53a connected to the steering wheel 51 side and an output shaft 53b connected to the rack and pinion gear 54 side. The input shaft 53a and the output shaft 53b are connected to each other by a torsion bar (not shown).

[0018] The torsion bar is disposed within the torque detector 22 and axially penetrates the torque detector 22. The torsion bar is twisted in response to the steering torque applied to the steering wheel 51 by the driver's operation, and the torque detector 22 detects the direction and amount of this twist. Hereinafter, the steering wheel 51, the steering shaft 53, and the torsion bar shall be collectively referred to as "steering".

[0019] The rack and pinion gear 54 includes a pinion gear (not shown) attached to the tip of the output shaft 53b and a rack (not shown) meshing with the pinion gear, and converts the rotational motion of the pinion gear into a reciprocating motion. The rack and the wheel 55 are connected via the tie rod 56 and the knuckle arm 57.

[0020] The torque detector 22 detects the steering torque applied to the torsion bar when the driver steers the steering wheel 51. When the steering torque is applied, the torsion bar is twisted by an amount approximately proportional to the steering torque. The torque detector 22 detects this twist angle and converts it into the steering torque T s The rotation detector 23 is attached to the rotating shaft of the rotary machine 1 and detects the rotational speed ω m of the rotating shaft.

[0021] The rotary machine 1 generates a steering assist torque for the steering under the control of the control device 2. The rotary machine 1 is composed of, for example, an AC motor such as a permanent magnet synchronous motor or an induction motor, or a DC motor. The control device 2 controls the rotary machine 1 based on the steering torque T s converted by the torque detector 22 and the rotational speed ω m detected by the rotation detector 23 to generate a steering assist torque for the steering.

[0022] Next, the operation of the electric power steering apparatus 50 will be described. In FIG. 1, when a steering torque is applied to the steering wheel 51 by a driver's steering operation, the steering torque is transmitted through the torsion bar and the steering shaft 53 in the torque detector 22 to the rack and pinion gear 54. Further, the steering torque is transmitted through the rack and pinion gear 54 to the rack in the rack and pinion gear 54. Then, on one side wheel 55, the tie rod 56 pushes the knuckle arm 57, and on the opposite side wheel 55, the tie rod 56 pulls the knuckle arm 57, so that a steering angle is given to the wheel 55 and the wheel 55 is steered.

[0023] On the other hand, when a steering torque is applied to the steering wheel 51 by a driver's steering operation, the steering torque is detected by the torque detector 22. Specifically, when a steering torque is applied, a twist approximately proportional to the steering torque occurs in the torsion bar, and the twist angle is detected by the torque detector 22 and converted into the steering torque T s Further, the rotational speed ω m of the rotating shaft of the rotary machine 1 is detected by the rotation detector 23.

[0024] The steering torque T s converted by the torque detector 22 and the rotational speed ω m detected by the rotation detector 23 are input to the control device 2, and a current command corresponding to the steering assist torque to be generated in the rotary machine 1 is determined according to these signals. Then, a current corresponding to the determined current command is supplied to the rotary machine 1, and a steering assist torque for steering is generated from the rotary machine 1. The steering assist torque generated from the rotary machine 1 is transmitted to the steering shaft 53 to reduce the steering torque applied by the driver during steering. The electric power steering apparatus 50 mounted on the vehicle is configured in this way, and applies the steering assist force by the rotary machine 1 to the steering wheel 51 and functions as an operation assist device.

[0025] <Steering measurement device> FIG. 2 is a block diagram showing a main configuration of a steering measurement device according to Embodiment 1 of the present disclosure. As shown in FIG. 2, in addition to a torque detector 22 and a rotation detector 23, a control device 2 includes a receiving unit 24, a transmitting unit 25, and a power supply unit 26. Note that the torque detector 22 and the rotation detector 23 are provided outside the control device 2 as shown in FIG. 1, but in FIG. 2, they are illustrated as components within the control device 2 for convenience.

[0026] The receiving unit 24 receives an identification signal output from the input / output device 3. The power supply unit 26 applies a voltage to the rotary machine 1 based on the identification signal received by the receiving unit 24. The torque detector 22 and the rotation detector 23 respectively detect a steering torque and a rotation speed, which are response data for the identification signal. The transmitting unit 25 transmits the identification signal and the response data to the input / output device 3.

[0027] A steering measurement device 60 according to the present embodiment is configured to be able to transmit and receive an identification signal and response data via an in-vehicle communication network NW between the input / output device 3 and the control device 2. Thereby, the control device 2 (the control device 2 that controls the rotary machine 1) provided in the electric power steering device 50 as a mass-produced product can perform the procedures necessary for identification, and identification of mechanical constants can be realized with a simple configuration.

[0028] The identification signal transmitted from the input / output device 3 to the control device 2 is a signal for generating a current command output from the power supply unit 26 to the rotary machine 1. This identification signal includes an identification signal (first identification signal) for identifying a linear parameter and an identification signal (second identification signal) for identifying a non-linear parameter. Here, the linear parameter is a parameter in which the output signal has a linear characteristic with respect to the input signal. In contrast, the non-linear parameter is a parameter in which the output signal has a non-linear characteristic with respect to the input signal.

[0029] The input / output device 3 identifies the parameters of the electric power steering device 50 based on the responses to an identification signal (first identification signal) for identifying linear parameters and an identification signal (second identification signal) for identifying non-linear parameters. Hereinafter, the identification of linear parameters based on the response to the identification signal for identifying linear parameters and the identification of non-linear parameters based on the response to the identification signal for identifying non-linear parameters will be described in order.

[0030] 《Identification of Linear Parameters》 As the identification signal for identifying linear parameters, a random signal such as an M-sequence signal including a predetermined power spectrum in a predetermined frequency band is used. The identification signal for identifying linear parameters may also be a sine sweep. The waveform by sine sweep has only a single frequency component at a certain time, while the waveform by pseudo-random numbers or random numbers generated by an M-sequence or the like includes a plurality of frequency components at a certain time. Therefore, a wide frequency band can be excited with a short-time excitation, and the frequency characteristics of steering can be efficiently obtained.

[0031] The identification signal command unit 4 performs control so that the speed sign of steering is the same when applying the above random signal. This is to reduce the influence of elements that change depending on the speed sign of the non-linear parameters described later, and is particularly effective when identifying a system having a characteristic with a large friction, which is a non-linear element. Here, as a method for realizing control so that the speed sign of steering is the same, for example, a method of constructing a feedback control system that detects the rotational speed of steering and adjusts the voltage applied to the rotary machine 1 so that this speed sign does not change can be mentioned. Also, a method of applying a ramp-like signal that changes at a constant rate over time to the rotary machine 1 can be mentioned.

[0032] When the friction, which is a non-linear parameter, is small, or when identification is performed based on response data in a region where the influence of the non-linear parameter is small as shown by the identification method of the linear parameters described later, it may be possible to apply the above random signal with the rotary machine 1 stopped. In such a case, the above random signal may be applied with the rotary machine 1 stopped.

[0033] The parameter identification unit 5 converts the transfer characteristics from the identification signal to the response data, i.e., the rotational speed signal and the steering torque signal, into frequency characteristics. For calculating the frequency characteristics, a generally known method may be applied. For example, a spectrum analysis method, a multi-decimation identification method, or a subspace method may be used. The parameter identification unit 5 can obtain frequency characteristics consisting of gain characteristics and phase characteristics shown by a Bode diagram as shown in FIG. 3.

[0034] FIG. 3 is a diagram showing the frequency characteristics of the response data with respect to the identification signal in Embodiment 1 of the present disclosure. The frequency characteristics shown in FIG. 3 are those obtained when the subspace method is used, and in addition to the Bode diagram, a mathematical model such as a state equation or a transfer function can also be obtained. In the graph shown in the upper part of FIG. 3, the solid line waveform is the gain characteristic from the excitation torque to the steering torque, and the broken line waveform is the gain characteristic from the excitation torque to the rotational speed. Also, in the graph shown in the lower part of FIG. 3, the solid line waveform is the phase characteristic from the excitation torque to the steering torque, and the broken line waveform is the phase characteristic from the excitation torque to the rotational speed.

[0035] Also, as shown in FIG. 3, the calculated frequency characteristics have several characteristic quantities. The parameter identification unit 5 also calculates the values of these characteristic quantities. For example, in the graph shown in the upper part of FIG. 3, the parameter identification unit 5 calculates the frequency at which the solid line and broken line waveforms become maximum peaks as the resonance frequency fr, and calculates the frequency at which the broken line waveform becomes a minimum peak as the anti-resonance frequency fn.

[0036] Furthermore, for the high-frequency part of the gain characteristic of the rotational speed shown enclosed by a frame in the graph shown in the upper part of FIG. 3, the parameter identification unit 5 sets the representative point to, for example, 100 Hz, and sets the gain at 100 Hz as the high-frequency gain Gh is calculated as. The parameter identification unit 5 also calculates the gain of the representative point as the high-frequency gain G of the high-frequency part of the gain characteristic of the steering torque. TS is calculated as. The parameter identification unit 5 also outputs these characteristic quantities as part of the frequency characteristics. The unit of the frequency is Hz, but the symbols of the frequencies converted to rad / s are the resonance frequency ωr and the anti-resonance frequency ωn.

[0037] The electric power steering device 50 is known to be approximately expressible as a two-inertia system of the moment of inertia J of the rotating machine 1 m , and the moment of inertia J of the steering wheel 51 sw . It is known that these moments of inertia and the four combined values of the stiffness K of the torsion bar and the viscosity C between the two inertias s between the two inertias are the linear parameters to be identified. Among the characteristic quantities of the frequency characteristics calculated above, the resonance frequency fr and the anti-resonance frequency fn change in value due to the friction characteristics which are non-linear elements, but the high-frequency gain G of the rotational speed s and the high-frequency gain G of the steering torque h are minimally affected by the non-linear elements. Therefore, by identifying the linear parameters from the high-frequency gain G of the rotational speed TS and the high-frequency gain G of the steering torque, it is possible to accurately identify a part of the linear parameters without being affected by the non-linear elements. h and the high-frequency gain G of the steering torque TS

[0038] The relational expressions between the linear parameters, the high-frequency gain G of the rotational speed h and the high-frequency gain G of the steering torque TS are derived from the equation of motion of the two-inertia system as shown in the following equations (1) and (2). Here, let ω H = 2·π·100. Note that the high-frequency gain G h selects the point of 100 Hz, but any high frequency that is not affected by the peak may be used. For example, a point within the range of three times or more the peak frequency and below the Nyquist frequency may be used. Alternatively, within a predetermined interval of that range, G h × ω H is averaged, and the following equation (1) is used for G h × ωH = 1 / J m It may be transformed as such.

[0039]

Math

Math

[0040] Here, G in Equation (2) n represents the gear ratio. From the above Equations (1) and (2), the following Equations (3) and (4) are obtained. Among the four unknown linear parameters, the moment of inertia J of the rotary machine 1 m and the stiffness K of the torsion bar between the two inertias s can be identified without being affected by the non - linear elements.

[0041]

Math

Math

[0042] Among the four unknown linear parameters, the moment of inertia J of the steering wheel 51 not identified above sw and the viscosity C of the torsion bar between the two inertias s are identified after the identification of the non - linear parameters described later. After the identification of the non - linear parameters, arbitrary values are given in the state of the moment of inertia J of the steering wheel 51, which is a linear parameter of the unknown parameters of the model, sw and the viscosity C of the torsion bar between the two inertias s and the steering torque and rotational speed, which are response data for an arbitrary input signal such as an M - series signal, are calculated by the following Equations (5) to (11).

[0043] Compare the calculated steering torque and rotational speed with the time-series waveforms of the steering torque and rotational speed detected by the torque detector 22 and the rotational detector 23, or the frequency characteristics calculated from the time-series waveforms, or both. Then, the moment of inertia J of the steering wheel 51 at which the calculated value and the detected value are closest sw and the viscosity C of the torsion bar between the two inertias s are identified by an optimization calculation. As the optimization calculation method, a generally known method (for example, the steepest descent method or the genetic algorithm, etc.) may be used. In particular, using a genetic algorithm such as the PSO (Particle Swarm Optimization) method has the effect of achieving global optimization.

[0044] 《Identification of Nonlinear Parameters》 As an identification signal for identifying the nonlinear parameter, a signal for controlling the steering so as to pass through the same angle of the steering with different speed signs is used. FIG. 4 is a block diagram showing an internal configuration example of the identification signal command unit in the first embodiment of the present disclosure. As shown in FIG. 4, the identification signal command unit 4 includes a speed command generation unit 6 and a speed control unit 7, and the speed control unit 7 performs feedback control so that the speed command output from the speed command generation unit 6 and the rotational speed of the rotating machine 1 output from the control device 2 match. Incidentally, the speed control unit 7 performs feedback control by, for example, PI control used as a general feedback control law.

[0045] Further, the above speed command may be stored in the speed command generation unit 6 in advance, or may be input from the outside of the input / output device 3 to the speed command generation unit 6. Incidentally, for the rotational speed command, the identification signal command unit 4 sets the same value during the period when the rotational speed commands have the same sign. This is to remove elements that depend on the speed change, and the details will be described later. With the above configuration, it becomes possible to generate a signal for controlling the steering so as to pass through the same angle of the steering with different speed signs.

[0046] By using a signal that controls the steering to pass through the same angle of the steering at different speed signs, as shown in FIG. 7, it is possible to detect the hysteresis of the output torque with respect to the steering angle. By using a signal that gives a current command controlled so that the rotational speed becomes constant, the rotational acceleration of the steering and the rotary machine 1 approaches 0, and by measuring at a plurality of rotational speeds, there is an effect that terms depending on the rotational speed can be extracted. When the electric power steering device 50 is expressed as a two-inertia system, the wheel 55 is simplified and replaced with a leaf spring, the equations of motion are represented by the following equations (5) to (8).

[0047]

Number

Number

Number

Number

[0048] θ h : Steering angle θ m : Rotor angle T h : Steering torque applied to the steering wheel by a hand operation T m : Output torque generated from the rotary machine K align : Leaf spring rigidity C align : Leaf spring viscosity X: Friction element

[0049] Regarding the steering torque T detected by the torque detector 22, the relational expression of the following equation (9) holds. s Regarding, the relational expression of the following equation (9) holds.

[0050]

Number

[0051] The input signal corresponds to the output torque T generated from the rotating machine 1 m and the output signal corresponds to the steering torque T detected by the torque detector 22 s and the rotational speed ω detected by the rotation detector 23 m . Also, the rotational angle θ of the rotating machine can be calculated from the rotational speed ω m . Although the friction elements need to be set according to the configuration of the device, in this embodiment, the friction elements fric1 and fric2 are set as in the following equation (10). m

[0052]

Equation

[0053] Here, sign(α) is a function that returns "1" if α is positive and "-1" if α is negative. In a state where a signal for giving a current command controlled so that the rotational speed becomes constant or a ramp-shaped current command signal is given, at a point where the time variation of the torque detection value is minute, that is, when extracting the point where (ω h - ω m / G n ) ≈ 0, the following equation (11) is obtained from the above equations (6) to (10).

[0054]

Equation

[0055] The right side of the above equation (11) can be calculated from the inertia moment J of the rotating machine 1 that can be identified regardless of the non-linear element in the input / output signal and linear parameter identification m . Also, if it is a current command controlled so that the rotational speed becomes constant, it is also possible to calculate assuming that the third term on the right side of the above equation (11) is approximately equal to 0. Using the input / output signals at N arbitrary times, the following equation (12) is obtained.

[0056] ​

Number

[0057] In the above formula (12), J is an evaluation function. By performing an optimization calculation with the leaf spring rigidity K align , the leaf spring viscosity C align , and the friction elements fric1 and fric2 as variables, the non-linear parameters are identified. As the optimization calculation method, a generally known method may be applied in the same manner as when identifying linear parameters.

[0058] FIG. 5 is a block diagram showing a modified example of the steering measurement device according to Embodiment 1 of the present disclosure. In the steering measurement device 60 shown in FIG. 5, the identification signal command unit 4 of the input / output device 3 outputs an instruction to start output of an identification signal instead of the identification signal, and an identification signal generation unit 27 is added to the control device 2.

[0059] In the steering measurement device 60 shown in FIG. 1, the identification signal command unit 4 outputs an identification signal to the control device 2. On the other hand, in the steering measurement device 60 shown in FIG. 5, the identification signal command unit 4 of the input / output device 3 outputs an instruction to start output of an identification signal to the control device 2, and the identification signal generation unit 27 of the control device 2 generates the identification signal. Note that the identification signal generated by the identification signal generation unit 27 includes an identification signal for linear parameters and an identification signal for non-linear parameters.

[0060] As described above, in the present embodiment, the identification signal command unit 4 outputs an identification signal or an instruction signal for instructing the start of output of the identification signal to the electric power steering device 50. Then, the parameter identification unit 5 identifies the parameters of the electric power steering device 50 based on the responses to the identification signal for identifying the linear parameters and the identification signal for identifying the non-linear parameters, which are output when the steering is in a predetermined rotational state. As a result, in addition to the linear parameters identified by the conventional method, the non-linear parameters not identified by the conventional method can also be identified with high accuracy. As a result, the accuracy of the bench analysis model for evaluating the characteristics of the electric power steering device 50 can be improved.

[0061] In addition, since the identification signal for identifying the linear parameters is a signal including a predetermined power spectrum in a predetermined frequency band, the identification of the linear parameters can be realized with a short excitation time. Further, since the identification signal for identifying the non-linear parameters is a signal for controlling the steering so as to pass through the same angle of the steering with different speed signs, the hysteresis of the output torque with respect to the steering angle can be detected, and the non-linear parameters can be identified with high accuracy.

[0062] Furthermore, in the present embodiment, the identification signal for identifying the non-linear parameters is generated so that the detected rotational speed of the steering matches the speed command. As a result, a remarkable effect that the rotational speed can be controlled to a predetermined state even under conditions where the friction characteristics, which are non-linear elements, are large, and the non-linear parameters can be identified with high accuracy is obtained.

[0063] 〔Embodiment 2〕 The steering measurement device 60 according to the above-described Embodiment 1 represents the electric power steering device 50 as a two-inertia system, simplifies the wheel 55, and identifies non-linear parameters based on the equation of motion when it is replaced with a leaf spring. In contrast, the steering measurement device 60 according to the present embodiment differs from the steering measurement device 60 according to the above-described Embodiment 1 in that the non-linear parameters to be identified are switched according to whether the electric power steering device 50 is connected to the vehicle or not.

[0064] Generally, a test for evaluating the performance of the electric power steering device 50 is often carried out with a leaf spring connected to the rack instead of the wheel 55. In such a case, the method for identifying the non-linear parameters described in Embodiment 1 is effective. On the other hand, a situation is also assumed in which the parameters of the electric power steering device 50 are identified with the electric power steering device 50 installed in an actual vehicle.

[0065] A leaf spring is a device for simply simulating the road surface reaction force of a vehicle, and has characteristics different from those of the road surface reaction force in an actual vehicle. Therefore, when applying the method for identifying the non-linear parameters described in Embodiment 1 to the electric power steering device 50 mounted on a vehicle, there is a problem that the reproduction accuracy of the road surface reaction force in the model used for the on-board analysis decreases. In the present embodiment, even when the electric power steering device 50 is installed in a vehicle, a model used for evaluating the electric power steering device 50 can be realized with high accuracy and simple calculations.

[0066] Since the characteristics of the road surface reaction force change between the state where a leaf spring is connected to the rack instead of the wheel 55 and the state where the electric power steering device 50 is installed in an actual vehicle, the linear parameters to be identified are the same, but the non-linear parameters are different. Among the equations (5) to (10) described in the identification of the non-linear parameters in Embodiment 1, the equations (8) and (10) related to the road surface reaction force are changed.

[0067] There are various models for expressing the road surface reaction force in an actual vehicle, such as the Dahl model, the LuGre model, and a model that calculates the contact area of the tire according to steering and obtains it from the friction coefficient. Therefore, it is selected according to the experimental environment or computer performance. In the present embodiment, instead of the above-described equation (8), the following equations (13), (14), and (15) newly derived based on the LuGre model are used.

[0068]

Number

Number

Number

[0069] Here, μ1(θ m ) is a function of the rotary machine angle θ m and is represented by an exponential function or a polynomial. Here, a quadratic function represented by the following equation (16) is used.

[0070]

Number

[0071] Since the above equations (13), (14), and (15) also model the friction element at the same time, the friction element is not modeled separately. That is, the above-described equation (10) is changed as follows in equation (17).

[0072]

Number

[0073] From the above-described equations (6), (7), (9) and the above equations (13) to (17), the following equation (18) is obtained.

[0074]

Number

[0075]

Equation

[0076] In the above equation (19), J′ is the evaluation function. Regarding the vehicle road reaction model parameters σ0, σ1, μ1(θ m ), and μ2 as variables, p is obtained from the input-output signals using the above equations (14) and (15), and by performing an optimization calculation so that the evaluation function J′ becomes minimum, it is possible to identify the non-linear parameters. Also, instead of obtaining the vehicle road reaction model parameters σ0, σ1, μ1(θ m ), and μ2 all at once as described above, it is also possible to identify them step by step.

[0077] FIG. 6 is a diagram showing the relationship between the rotary machine angle and the vehicle road reaction in Embodiment 2 of the present disclosure. Note that in the graph shown in FIG. 6, the horizontal axis represents the rotary machine angle (converted to the rotary machine axis), and the vertical axis represents the value on the right side of equation (18). The locus of the rotary machine angle and the road reaction shown in FIG. 6 changes clockwise from the state where the rotary machine angle and the road reaction are 0. Then, the identification is carried out by dividing it into three regions (“Region 1”, “Region 2”, “Region 3”).

[0078] “Region 1” is (θ h ≧0 ∩ ω h <0) ∪ (θ h <0 ∩ ω h ≧0), and it is a region where the change on the right side of the above equation (18) is small. “Region 2” is (θ h ≧0 ∩ ω h ≧0) ∪ (θh <0∩ω h is the region of <0). "Region 3" is (θ h ≧0∩ω h ≧0) ∪ (θ h <0∩ω h <0) and (θ h ≧0∩ω h <0) ∪ (θ h <0∩ω h ≧0), and is the region during the switching between "Region 1" and "Region 2".

[0079] First, in "Region 1", the following relationship of formula (20) holds.

[0080]

Number

[0081] From the above formula (20), using the input and output signals at N arbitrary times in "Region 1", the following formula (21) is obtained.

[0082]

Number

[0083] In the above formula (21), J″ is an evaluation function. By performing optimization calculation with the vehicle road surface reaction force model parameters σ1 and μ2 as variables so that the evaluation function J″ becomes minimum, σ1 and μ2 can be identified. In "Region 2". The following relationship of formula (22) holds.

[0084]

Number

[0085] The right side of the above formula (22) can be calculated from the input and output signals and the identification result of σ1. According to the least squares method, the coefficients are obtained in accordance with the expression method of μ1(θ m ). As shown in the above formula (16) described above, μ1(θm ) is replaced with a quadratic function, and polynomial approximation is performed by the least squares method so as to match the right side of equation (22), and the coefficients a1, a2, and a3 of μ1(θ m ) are obtained.

[0086] Finally, in "Region 3", using the aforementioned equations (14) and (15) with the vehicle road surface reaction force model parameter σ0 as a variable, p is obtained from the input / output signals, and σ0 can be identified by performing an optimization calculation so that the evaluation function J′ becomes minimum. Since the identification accuracy of each non-linear parameter to be identified and the range of values that the coefficients of the polynomial of μ1(θ m ) can take are wide, there is an effect that high-precision identification can be achieved by directly performing polynomial approximation.

[0087] In this way, by setting the non-linear parameters according to the state where the electric power steering device 50 is installed in an actual vehicle, there is an effect that the identification of the non-linear parameters can be carried out with high precision. Also, by identifying the non-linear parameters with high precision, the moment of inertia J of the steering wheel 51 of the linear parameters to be identified after the identification of the non-linear parameters sw and the viscosity C of the torsion bar between the two inertias s can be identified with high precision.

[0088] Incidentally, in the present embodiment, an example in which the non-linear parameters to be identified are switched according to whether or not the electric power steering device 50 is connected to the vehicle has been described. However, a configuration in which the identification signal for identifying the non-linear parameters is switched may also be used. When the electric power steering device 50 is connected to the vehicle, not only when the vehicle is stopped but also when the vehicle is running, the parameters of the electric power steering device 50 may be identified.

[0089] When the vehicle is in a stopped state and a running state, since the vehicle road surface reaction force changes, it is effective to use an identification signal suitable for the state in which the electric power steering device 50 is connected to the vehicle. As an identification signal suitable for the state of being connected to the vehicle, for example, there is an operation of changing the amplitude of a random signal which is an identification signal for identifying a linear parameter, or a speed command used for speed control when identifying a non-linear parameter, according to the vehicle speed.

[0090] As described above, the input / output device 3 according to the present embodiment switches the non-linear parameter to be identified by the parameter identification unit 5 according to whether or not the electric power steering device 50 is connected to the vehicle. Thereby, a remarkable effect that the road surface reaction force which is a non-linear parameter in an actual vehicle can be accurately identified and the accuracy of the model used for the evaluation of the electric power steering device 50 can be improved is obtained.

[0091] Also, in the input / output device 3 according to the present embodiment, it is also possible to configure the identification signal command unit 4 to switch the identification signal according to whether or not the electric power steering device 50 is connected to the vehicle. Thereby, an appropriate identification signal can be generated according to the running state of the vehicle, and an effect that the parameters of the electric power steering device 50 connected to the vehicle can be identified with high accuracy is obtained.

[0092] Furthermore, the input / output device 3 according to the present embodiment makes the non-linear parameter include an exponential function or a polynomial regarding the state of the electric power steering device 50. Thereby, the road surface reaction force in an actual vehicle can be expressed by a simple approximation formula, and an effect that the model used for the evaluation of the electric power steering device 50 can be realized with high accuracy and simple calculation is obtained.

[0093] [Embodiment 3] The steering measurement device 60 according to the above-described Embodiment 1 generated an identification signal for identifying non-linear parameters such that the detected rotation speed of the steering matched the speed command. In contrast, the steering measurement device 60 according to the present embodiment is different from the steering measurement device 60 according to the above-described Embodiment 1 in that a signal that changes in a ramp shape is used as the identification signal.

[0094] In a general electric power steering device 50, feedback control for detecting the rotation speed and generating a current command so that the rotation speed matches the speed command is not performed. For this reason, the non-linear parameter identification method shown in Embodiment 1 needs to perform feedback control that is unnecessary for the mass-produced electric power steering device 50, and there is a concern that the software capacity will increase. Therefore, in the present embodiment, a signal that changes in a ramp shape is used as the identification signal for non-linear parameters, and the identification of non-linear parameters is realized by simple calculation.

[0095] FIG. 7 is a diagram showing a signal that changes in a ramp shape and is used as an identification signal in Embodiment 3 of the present disclosure. In FIG. 7, in addition to the identification signal, signals indicating the steering angle and the steering speed with respect to the identification signal are also shown. As shown in FIG. 7, the signal that changes in a ramp shape is a signal that changes at a constant rate over time. Since this signal passes through the same angle of the same steering with different speed signs, it is necessary to have a shape that includes both a period T11 of increasing in the positive direction and a period T12 of increasing in the negative direction.

[0096] Also, as a method for generating a signal that changes in a ramp shape, a method can be considered in which a counter is incremented or decremented for each calculation cycle of signal generation, and the result of multiplying the count value by a predetermined gain is used as the identification signal. In the above signal generation, complicated calculations or arithmetic processing in a short cycle are not required, and non-linear parameter identification can be realized by simple signal generation processing as compared with the case of using feedback control of the rotation speed.

[0097] As described above, the input / output device 3 according to the present embodiment uses a lamp-shaped signal that changes at a constant rate over time as an identification signal for identifying non-linear parameters. Therefore, feedback control of the rotational speed becomes unnecessary, and a remarkable effect is obtained in that non-linear parameters can be identified with high accuracy only by simple signal generation processing.

[0098] Although the embodiments have been described above, the present disclosure is not limited to the above-described embodiments, and can be freely changed without departing from the spirit of the present disclosure. For example, the electric power steering device 50 described in the above-described embodiment is of a rack and pinion type, but may be of a type other than the rack and pinion type.

[0099] Each component (control device 2, input / output device 3) included in the steering measurement device 60 described above has a computer system inside. Then, a program for realizing the functions of each component included in the steering measurement device 60 described above is recorded on a computer-readable recording medium, and the program recorded on this recording medium is read into the computer system and executed, thereby performing the processing in each component included in the steering measurement device 60 described above. Here, "reading and executing the program recorded on the recording medium into the computer system" includes installing the program in the computer system. The "computer system" here is assumed to include hardware such as an OS and peripheral devices.

[0100] Further, the "computer system" may include a plurality of computer devices connected via a network including a communication line such as the Internet, WAN, LAN, or dedicated line. Also, the "computer-readable recording medium" refers to a portable medium such as a flexible disk, magneto-optical disk, ROM, CD-ROM, or a storage device such as a hard disk built into the computer system. Thus, the recording medium storing the program may be a non-transitory recording medium such as a CD-ROM.

[0101] In addition, the recording medium also includes an internal or external recording medium provided so as to be accessible from a distribution server for distributing the program. Note that the program may be divided into a plurality of parts, and may be configured to be combined by each component included in the steering measurement device 60 after being downloaded at different timings. Also, the distribution servers for distributing the respective divided programs may be different. Furthermore, the “computer-readable recording medium” includes those that hold a program for a certain period of time, such as a volatile memory (RAM) inside a computer system that becomes a server or a client when the program is transmitted via a network. Also, the above program may be for realizing a part of the functions described above. Furthermore, it may be a so-called difference file (difference program) that can realize the functions described above in combination with a program already recorded in the computer system.

Explanation of Signs

[0102] 1... Rotating machine, 2... Control device, 3... Input / output device, 4... Signal command unit for identification, 5... Parameter identification unit, 27... Signal generation unit for identification, 50... Electric power steering device, 60... Steering measurement device, NW... In-vehicle communication network

Claims

1. For an electric power steering device that adds a steering assist force to a steering provided in a vehicle, an identification signal for identifying parameters of the electric power steering device, or an identification signal command unit that outputs an instruction signal for instructing the start of output of the identification signal to the electric power steering device, a parameter identification unit that identifies parameters of the electric power steering device from the response of the electric power steering device to the identification signal, comprising: The parameter identification unit identifies parameters of the electric power steering device based on responses to a first identification signal for identifying linear parameters and a second identification signal for identifying non-linear parameters, which are output when the steering is in a predetermined rotational state. Input / output device.

2. The first identification signal is a signal including a predetermined power spectrum in a predetermined frequency band, The second identification signal is a signal for controlling the steering so as to pass through the same angle of the steering with different speed signs, The input / output device according to Claim 1.

3. The identification signal command unit controls so that the speed signs of the steering are the same when the first identification signal is applied. The input / output device according to Claim 2.

4. The second identification signal is generated so that the detected rotational speed of the steering matches a speed command. The input / output device according to Claim 2.

5. The second identification signal is a lamp-shaped signal that changes at a constant rate over time. The input / output device according to Claim 2.

6. The parameter identification unit switches non-linear parameters to be identified according to whether the electric power steering device is connected to the vehicle. The input / output device according to Claim 1.

7. The identification signal command unit switches the identification signal according to whether the electric power steering device is connected to the vehicle. The input / output device according to Claim 1.

8. The non-linear parameters include an exponential function or a polynomial related to the state of the electric power steering device. The input / output device according to Claim 1.

9. The input / output device according to any one of Claims 1 to 8, and A control device that is connected to the input / output device via an in-vehicle communication network provided in the vehicle, controls a rotating machine provided in the electric power steering device to add a steering assist force to the steering based on the first identification signal or the second identification signal, and outputs response data indicating the response of the electric power steering device to the first identification signal or the second identification signal to the input / output device via the in-vehicle communication network; A steering measurement device comprising the same. **Claim 10** The steering measurement device according to claim 9, wherein the control device includes an identification signal generation unit that outputs the first identification signal or the second identification signal based on the instruction signal output from the identification signal command unit of the input / output device.

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