CN111006885B - Method and device for calibrating EPS (electric power steering) model parameters of electric power steering system - Google Patents
Method and device for calibrating EPS (electric power steering) model parameters of electric power steering system Download PDFInfo
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Abstract
The invention provides a method and a device for calibrating EPS model parameters of an electric power steering system, which aim to realize targeted parameter adjustment of simulation characteristic parameters of an EPS. The method comprises the following steps: determining a plurality of EPS model parameters affecting a simulation characteristic curve of the EPS; the plurality of EPS model parameters includes: the motor torque characteristic parameter, the steering rack friction force parameter, the gear-rack transmission ratio parameter and the damping coefficient; determining a calibration sequence of the EPS model parameters; and sequentially calibrating the plurality of EPS model parameters according to the calibration sequence so as to enable the simulation curve of the EPS to be close to the real characteristic curve. Therefore, in the embodiment of the invention, the PES model parameters influencing the simulation characteristic curve of the EPS are determined firstly, then the calibration sequence of the EPS model parameters is determined, and the EPS model parameters are calibrated in a targeted manner according to the calibration sequence, so that the calibration process is not blind, and the parameter adjusting time is saved.
Description
Technical Field
The invention relates to the technical field of automotive electronics, in particular to a method and a device for calibrating EPS (electric power steering) model parameters of an electric power steering system.
Background
An electric power steering system (EPS) includes a torque sensor, an electronic control unit, and the like. When a driver steers a steering wheel, a torque sensor detects the steering of the steering wheel and the magnitude of torque (torque), voltage signals are transmitted to an electronic control unit, and the electronic control unit sends instructions to a motor controller according to the torque voltage signals, the rotating direction, a vehicle speed signal and the like detected by the torque sensor, so that the motor outputs steering power-assisted torque, and auxiliary power is generated.
Before leaving the factory, the electronic control unit of the EPS needs to be subjected to HIL (hardware-in-the-loop) simulation test. In the process of carrying out the simulation test, the steering wheel angle of a vehicle dynamic model (used for simulating the running of a real vehicle) is calculated based on a simulation characteristic curve (torque and steering wheel angle curve) of EPS in simulation test software according to an instruction output by a tested electronic control unit so as to control the running of the vehicle dynamic model.
In order to make the test approach the real situation, the simulated characteristic curve of EPS should be adapted to the real characteristic curve. However, parameters affecting the characteristic curve are numerous, and a calibration process does not exist at present, so that the parameter adjusting process is very blind and has no pertinence, and a lot of time is consumed.
Disclosure of Invention
In view of this, the embodiment of the invention provides a method and a device for calibrating EPS model parameters of an electric power steering system, so as to realize targeted parameter adjustment of simulation characteristic parameters of an EPS.
In order to achieve the above purpose, the embodiments of the present invention provide the following technical solutions:
a method for calibrating EPS model parameters of an electric power steering system comprises the following steps:
determining a plurality of EPS model parameters affecting a simulation characteristic curve of the EPS; the plurality of EPS model parameters includes: the motor torque characteristic parameter, the steering rack friction force parameter, the gear-rack transmission ratio parameter and the damping coefficient;
determining a calibration sequence of the EPS model parameters;
and sequentially calibrating the plurality of EPS model parameters according to the calibration sequence so as to enable the simulation curve of the EPS to be close to the real characteristic curve.
Optionally, the sequentially calibrating the multiple EPS model parameters includes:
adjusting the parameter value of the motor torque characteristic parameter to adjust the curvature and the amplitude of the simulation characteristic curve until a first condition is met; wherein the motor torque characteristic parameter value satisfying the first condition is a target motor torque characteristic parameter value;
adjusting the parameter value of the friction force parameter of the steering rack to adjust the cross section of the simulation characteristic curve until a second condition is met; the steering rack friction parameter value meeting the second condition is a target steering rack friction parameter value;
adjusting the parameter value of the gear-rack transmission ratio parameter to adjust the amplitude of the simulation characteristic curve until a third condition is met; the gear and rack transmission ratio parameter value meeting the third condition is a target gear and rack transmission ratio parameter value;
adjusting the parameter value of the damping coefficient to scale the simulation characteristic curve until a fourth condition is met; wherein the damping coefficient value satisfying the fourth condition is a target damping coefficient value;
and saving the target motor torque characteristic parameter value, the target steering rack friction force parameter value, the target gear-rack transmission ratio parameter value and the target damping coefficient value as calibrated parameter values.
Optionally, the first condition includes: the slope ratio of the simulated characteristic curve to the real characteristic curve is in a first ratio range, and the amplitude ratio of the simulated characteristic curve to the real characteristic curve is in a second ratio range; the second condition includes: the difference value of the cross-sectional distances of the simulated characteristic curve and the real characteristic curve is within the range of the cross-sectional distances; the third condition includes: the ratio of the amplitude difference between the simulated characteristic curve and the real characteristic curve to the amplitude of the real characteristic curve is within a third ratio range; the fourth condition includes: the ratio of the slope of the simulated characteristic to the slope of the real characteristic is less than a first threshold, and the ratio or difference of the magnitude of the simulated characteristic to the magnitude of the real characteristic is less than a second threshold.
Optionally, the determining a plurality of EPS model parameters that affect the simulation characteristic curve of the EPS includes:
determining candidate EPS model parameters influencing the simulation characteristic curve of the EPS;
and screening the plurality of EPS model parameters from the candidate EPS model parameters by using a control variable method.
The utility model provides an electric power steering system EPS model parameter calibration device, includes:
a screening unit for:
determining a plurality of EPS model parameters affecting a simulation characteristic curve of the EPS; the plurality of EPS model parameters includes: the motor torque characteristic parameter, the steering rack friction force parameter, the gear-rack transmission ratio parameter and the damping coefficient;
determining a calibration sequence of the EPS model parameters;
a calibration unit for:
and sequentially calibrating the plurality of EPS model parameters according to the calibration sequence so as to enable the simulation curve of the EPS to be close to the real characteristic curve.
Optionally, in the aspect of sequentially calibrating the multiple EPS model parameters, the calibration unit is specifically configured to:
adjusting the parameter value of the motor torque characteristic parameter to adjust the curvature and the amplitude of the simulation characteristic curve until a first condition is met; wherein the motor torque characteristic parameter value satisfying the first condition is a target motor torque characteristic parameter value;
adjusting the parameter value of the friction force parameter of the steering rack to adjust the cross section of the simulation characteristic curve until a second condition is met; the steering rack friction parameter value meeting the second condition is a target steering rack friction parameter value;
adjusting the parameter value of the gear-rack transmission ratio parameter to adjust the amplitude of the simulation characteristic curve until a third condition is met; the gear and rack transmission ratio parameter value meeting the third condition is a target gear and rack transmission ratio parameter value;
adjusting the parameter value of the damping coefficient to scale the simulation characteristic curve until a fourth condition is met; wherein the damping coefficient value satisfying the fourth condition is a target damping coefficient value;
and saving the target motor torque characteristic parameter value, the target steering rack friction force parameter value, the target gear-rack transmission ratio parameter value and the target damping coefficient value as calibrated parameter values.
Optionally, the first condition includes: the slope ratio of the simulated characteristic curve to the real characteristic curve is in a first ratio range, and the amplitude ratio of the simulated characteristic curve to the real characteristic curve is in a second ratio range; the second condition includes: the difference value of the cross-sectional distances of the simulated characteristic curve and the real characteristic curve is within the range of the cross-sectional distances; the third condition includes: the ratio of the amplitude difference between the simulated characteristic curve and the real characteristic curve to the amplitude of the real characteristic curve is within a third ratio range; the fourth condition includes: the ratio of the slope of the simulated characteristic to the slope of the real characteristic is less than a first threshold, and the ratio of the amplitude of the simulated characteristic to the amplitude of the real characteristic is less than a second threshold.
Optionally, in the aspect of determining a plurality of EPS model parameters that affect the simulation characteristic curve of the EPS, the screening unit is specifically configured to: determining candidate EPS model parameters influencing the simulation characteristic curve of the EPS; and screening the plurality of EPS model parameters from the candidate EPS model parameters by using a control variable method.
Therefore, in the embodiment of the invention, the PES model parameters influencing the simulation characteristic curve of the EPS are determined firstly, then the calibration sequence of the EPS model parameters is determined, and the EPS model parameters are calibrated in a targeted manner according to the calibration sequence, so that the calibration process is not blind, and the parameter adjusting time is saved.
Drawings
FIG. 1 is a diagram illustrating an example hardware architecture of an HIL environment according to an embodiment of the present invention;
fig. 2 is an exemplary structural diagram of an EPS model parameter calibration apparatus provided in an embodiment of the present invention;
FIG. 3 is a schematic diagram of a simulated characteristic curve and a real vehicle curve provided by an embodiment of the invention;
fig. 4 is an exemplary interaction flow of an EPS model parameter calibration method according to an embodiment of the present invention;
fig. 5a to 5h are schematic diagrams illustrating the influence of each EPS model parameter on a characteristic curve according to an embodiment of the present invention;
fig. 6a-6d are schematic diagrams illustrating comparison between a simulated characteristic curve and a real vehicle curve in an adjustment process according to an embodiment of the present invention.
Detailed Description
The invention provides a method and a device for calibrating EPS model parameters of an electric power steering system, which aim to realize targeted parameter adjustment of simulation characteristic parameters of the EPS in an HIL environment.
An exemplary hardware architecture for constructing the HIL environment is shown in fig. 1, which may include at least: an upper computer, an HIL (hardware-in-the-loop) lower computer and an EPS electronic control unit.
The EPS model parameter calibration device can be used as a component or a module of the simulation test platform to be deployed in the upper computer, and can interact with testers through the human-computer interaction platform.
Specifically, referring to fig. 2, the EPS model parameter calibration apparatus may include a screening unit 1 and a calibration unit 2.
Wherein, screening unit 1 is used for: determining a plurality of EPS model parameters influencing the simulation characteristic curve of the EPS, and determining the calibration sequence of the EPS model parameters.
The above "plurality" is used to indicate at least two.
In one example, the determined plurality of EPS model parameters may include: motor torque characteristic parameters, steering rack friction force parameters, gear and rack transmission ratio parameters and damping coefficients.
The calibration sequence is then: the motor torque characteristic parameter- > steering rack friction force parameter- > gear and rack transmission ratio parameter- > damping coefficient.
The calibration unit 2 is used for: and sequentially calibrating the plurality of EPS model parameters according to the calibration sequence so as to enable the simulation curve of the EPS to be close to the real characteristic curve.
The characteristic curve of the EPS includes a torque-steering wheel angle response curve.
Taking a certain vehicle model as an example, a real torque-steering wheel angle response curve collected in a road test experiment is shown in fig. 3. The dashed curve corresponding to "real" in fig. 3 is a real torque-steering wheel angle response curve (called a real curve for short), and because the EPS may delay in responding to the first torque, the real curve may have an isolated dashed segment at the beginning.
The solid curve corresponding to "sim" in fig. 3 is a simulated characteristic curve, i.e., a simulated curve for a real vehicle curve in the HIL environment.
The abscissa in fig. 3 represents torque (Steer Tor) in Nm and the ordinate represents steering wheel angle (Steer Ang) in Deg. Since the steering wheel can be turned to the left or right, the turning angle is divided into positive and negative, and the torque is divided into positive and negative (the meaning of the abscissa and ordinate is equally applicable to fig. 5a to 5h, 6a to 6 d).
The core idea of the invention is as follows: the method comprises the steps of firstly determining a plurality of PES model parameters influencing an EPS simulation characteristic curve, then determining a calibration sequence of the plurality of EPS model parameters, and calibrating the EPS model parameters in a targeted manner according to the calibration sequence, so that a calibration process is not blind any more, and parameter adjusting time is saved.
In the following, how to determine the above-mentioned multiple EPS model parameters and how to perform calibration will be described in detail.
Fig. 4 shows an exemplary interaction flow of the EPS model parameter calibration method based on the EPS model parameter calibration apparatus, which may include:
s1: candidate EPS model parameters that affect the simulated characteristic curve of the EPS are determined.
Candidate EPS model parameters may be determined by analyzing the mechanical system of the vehicle steering mechanism and the EPS.
Specifically, parameters affecting the mechanical system (e.g., steering gear, steering wheel, gimbal link, springs) may be determined by analyzing the effect of each EPS model parameter on the mechanical system.
In addition, the parameters that affect the operation of the EPS may be determined by actually adjusting each parameter to determine the effect on the EPS.
The candidate EPS model parameters obtained by the above analysis are shown in table 1 below:
TABLE 1
S2: and screening the plurality of EPS model parameters from the candidate EPS model parameters by using a control variable method.
The core of the control variable method is that only one parameter is changed each time, and the rest parameters are controlled to be unchanged.
In this embodiment, a control variable method is used to gradually change each candidate EPS model parameter, determine the specific influence of the candidate EPS model parameter on the characteristic curve (as shown in fig. 5a-5 h), and screen out important parameters and auxiliary adjusting parameters from the candidate EPS model parameters, where the important parameters and the auxiliary adjusting parameters are shown in table 2 below.
TABLE 2
Finally, the screened EPS model parameters include: motor torque characteristic parameters, steering rack friction force parameters, gear and rack transmission ratio parameters and damping coefficients.
S3: and determining the calibration sequence of the EPS model parameters.
In one example, the calibration order may be: the motor torque characteristic parameter- > steering rack friction force parameter- > gear and rack transmission ratio parameter- > damping coefficient.
It should be noted that steps S1-S3 do not need to be executed every time the calibration is performed. When the simulation test is performed by exchanging the vehicle model, the steps S1-S3 may be performed again.
S4: and adjusting the parameter value of the motor torque characteristic parameter to adjust the curvature and the amplitude of the simulation characteristic curve until a first condition is met.
The motor torque characteristic parameter represents the relation between current and output torque.
If the motor torque characteristic parameter is decreased (or increased), the input torque value of the EPS is decreased (or increased) accordingly, and the parameter directly affects the slope and amplitude of the simulation characteristic curve.
In one example, the first condition may include:
the ratio of the slopes of the simulated characteristic to the real characteristic is within a first ratio range, and the ratio of the magnitudes of the simulated characteristic to the real characteristic is within a second ratio range.
It should be noted that under normal operating conditions, the steering wheel is not normally dead, and therefore, referring to the real characteristic curve in fig. 6a, the change in the angle of the steering wheel and the change in the torque often fall on the line segment between the point h and the point i, and the line segment between the point k and the point j. Alternatively, the relationship between the steering wheel angle and the torque has two working ranges (a line segment between the point h and the point i is one working range, and a line segment between the point k and the point j is one working range).
The slope of the line segment between the point h-the point i, or the slope of the line segment between the point k to the point j may be used as the slope of the true characteristic curve.
Specifically, the slope of the real characteristic curve may be the average of the slope at the point h and the slope at the point i, or the slope of the real characteristic curve may be the average of the slope at the point k and the slope at the point j.
For the analog characteristic, the slope of its operating region may also be taken. Please refer to the simulated characteristic curve of fig. 6a, the working interval includes a line segment from point c to point d, and a line segment from point a to point b.
Specifically, the slope of the analog characteristic curve may be the average of the slope at the point c and the slope at the point d, or the slope of the analog characteristic curve may be the average of the slope at the point a and the slope at the point b.
And the amplitude refers to the difference between the maximum and minimum values on the vertical axis.
Specifically, the first ratio range may be 1/3 ± Δ, and the second ratio range may be 1/3 ± Δ, where Δ may be flexibly designed according to needs.
That is, when the slope of the simulated characteristic curve is about 1/3 and the magnitude is about 1/3 of the true vehicle curve, the adjustment of the motor torque characteristic parameter may be ended.
Before the non-adjustment, the simulated characteristic curve and the real vehicle curve are shown in fig. 3. At the end of this step, the simulated characteristic curve and the real vehicle curve are shown in fig. 6 a.
The motor torque characteristic parameter value satisfying the above-described first condition may be referred to as a target motor torque characteristic parameter value (i.e., a current parameter value at which the adjustment of the motor torque characteristic parameter is finished).
S5: and adjusting the parameter value of the friction force parameter (maximum friction force) of the steering rack to adjust the cross section of the simulation characteristic curve until a second condition is met.
The abscissa intercept (abscissa intercept) refers to the distance between two points at which the direction of the abscissa of the zero crossing point intersects the curve.
In one example, the second condition may specifically include: the difference of the cross-sectional distances of the simulated characteristic curve and the real characteristic curve is within the cross-sectional distance range.
Wherein, the cross-sectional distance range can be d, wherein d can be flexibly designed according to requirements.
That is, when the cross-sectional distance of the simulated characteristic curve and the cross-sectional distance of the true vehicle curve are approximately equal, this step may be ended.
The steering rack friction parameter value meeting the second condition is a target steering rack friction parameter value;
the steering rack friction parameter value satisfying the second condition may be referred to as a target steering rack friction parameter value (i.e., a current parameter value at which adjustment of the steering rack friction parameter is finished).
At the end of this step, the simulated characteristic curve and the real vehicle curve are shown in fig. 6 b.
S6: and adjusting the parameter value of the gear-rack transmission ratio parameter to adjust the amplitude of the simulation characteristic curve until a third condition is met.
In one example, the third condition may specifically include: the ratio of the amplitude difference between the simulated characteristic curve and the real characteristic curve to the amplitude of the real characteristic curve is within a third ratio range.
Specifically, the third ratio range may be 30% ± Δ. That is, when the ratio of the amplitude difference to the amplitude of the real characteristic curve is within about 30%, the step can be terminated.
The value of the rack-and-pinion gear ratio parameter that satisfies the third condition may be referred to as a target rack-and-pinion gear ratio parameter value (i.e., a current parameter value at which adjustment of the rack-and-pinion gear ratio parameter is finished).
At the end of this step, the simulated characteristic curve and the real vehicle curve are shown in fig. 6 c.
Steps S4-S6 may be referred to as a coarse tuning phase, and a fine tuning phase using the auxiliary tuning parameters is entered below.
S7: and adjusting the parameter value of the damping coefficient to scale the simulation characteristic curve until a fourth condition is met.
By adjusting the damping coefficient, the analog characteristic curve can be scaled, and the amplitude and the slope of the analog characteristic curve can be finely adjusted (the adjustment range is about plus or minus 10 percent).
In one example, the fourth condition may specifically include: the ratio of the slope of the simulated characteristic to the slope of the true characteristic is less than a first threshold, and the ratio of the magnitude of the simulated characteristic to the magnitude of the true characteristic is less than a second threshold.
The first threshold value and the second threshold value can be flexibly set according to the situation, and the aim is to make the simulated characteristic curve similar to the real characteristic curve as much as possible. At the end of this step, the simulated characteristic curve and the real vehicle curve are shown in fig. 6 d.
The damping coefficient value satisfying the fourth condition may be referred to as a target damping coefficient value (i.e., the current parameter value at which the adjustment of the damping coefficient is finished).
S8: and saving the target motor torque characteristic parameter value, the target steering rack friction force parameter value, the target gear-rack transmission ratio parameter value and the target damping coefficient value as calibrated parameter values.
It should be noted that the slope, the amplitude, the cross-sectional distance, the difference of the amplitude and the difference of the cross-sectional distance mentioned above are all absolute values.
In the subsequent simulation test, the vehicle performance test is carried out by using the saved parameter values.
Compared with the previous algorithm test, the simulation test executed based on the calibration scheme provided by the invention can adapt the EPS characteristic response curve of the real vehicle to vehicle simulation software on one hand. Therefore, the algorithm can be more accurately tested in the HIL environment, the response problem of the actuator can be eliminated aiming at certain problem points, and the problem points in the algorithm can be further positioned. On the other hand, the engineering calibration method clarifies the parameter screening process and parameter adjusting steps, the real characteristic curve of the vehicle can be firstly collected for different vehicle types, then the screened EPS model parameters are adjusted according to the determined calibration sequence, and the response curve can be quickly applied to the HIL environment.
An EPS model parameter calibration apparatus is described below.
Referring to fig. 2, the EPS model parameter calibration apparatus may include a screening unit 1 and a calibration unit 2.
Wherein, screening unit 1 is used for: determining a plurality of EPS model parameters influencing the simulation characteristic curve of the EPS, and determining the calibration sequence of the EPS model parameters.
The above "plurality" is used to indicate at least two.
In one example, the determined plurality of EPS model parameters may include: motor torque characteristic parameters, steering rack friction force parameters, gear and rack transmission ratio parameters and damping coefficients.
The calibration sequence is then: the motor torque characteristic parameter- > steering rack friction force parameter- > gear and rack transmission ratio parameter- > damping coefficient.
The calibration unit 2 is used for: and sequentially calibrating the plurality of EPS model parameters according to the calibration sequence so as to enable the simulation curve of the EPS to be close to the real characteristic curve.
In other embodiments of the present invention, in terms of sequentially calibrating the multiple EPS model parameters, the calibration unit 2 in all the embodiments may specifically be configured to:
adjusting the parameter value of the motor torque characteristic parameter to adjust the curvature and the amplitude of the simulation characteristic curve until a first condition is met; the motor torque characteristic parameter value meeting the first condition is a target motor torque characteristic parameter value;
adjusting the parameter value of the friction force parameter of the steering rack to adjust the cross section of the simulation characteristic curve until a second condition is met; the steering rack friction parameter value meeting the second condition is a target steering rack friction parameter value;
adjusting the parameter value of the gear-rack transmission ratio parameter to adjust the amplitude of the simulation characteristic curve until a third condition is met; the gear and rack transmission ratio parameter value meeting the third condition is a target gear and rack transmission ratio parameter value;
adjusting the parameter value of the damping coefficient to scale the simulation characteristic curve until a fourth condition is met; wherein the damping coefficient value satisfying the fourth condition is a target damping coefficient value;
and saving the target motor torque characteristic parameter value, the target steering rack friction force parameter value, the target gear-rack transmission ratio parameter value and the target damping coefficient value as calibrated parameter values.
In one example:
the first condition may include: the slope ratio of the simulated characteristic curve to the real characteristic curve is in a first ratio range, and the amplitude ratio of the simulated characteristic curve to the real characteristic curve is in a second ratio range;
the second condition may include: the difference value of the cross-sectional distances of the simulated characteristic curve and the real characteristic curve is within the range of the cross-sectional distance;
the third condition may include: the ratio of the amplitude difference between the simulated characteristic curve and the real characteristic curve to the amplitude of the real characteristic curve is within a third ratio range;
the fourth condition may include: the ratio of the slope of the simulated characteristic to the slope of the true characteristic is less than a first threshold, and the ratio of the magnitude of the simulated characteristic to the magnitude of the true characteristic is less than a second threshold.
For details, please refer to the above description, which is not repeated herein.
In other embodiments of the present invention, in terms of determining a plurality of EPS model parameters that affect a simulation characteristic curve of an EPS, the screening unit 1 in all the above embodiments may be specifically configured to:
determining candidate EPS model parameters influencing the simulation characteristic curve of the EPS;
and screening a plurality of EPS model parameters from candidate EPS model parameters by using a control variable method.
For details, please refer to the above description, which is not repeated herein.
The embodiments in the present description are described in a progressive manner, each embodiment focuses on differences from other embodiments, and the same and similar parts among the embodiments are referred to each other. For the device disclosed in the embodiment, since it corresponds to the method disclosed in the embodiment, the description is simple, and the description can be referred to the method part.
Those of skill would further appreciate that the various illustrative components and model steps described in connection with the embodiments disclosed herein may be implemented as electronic hardware, computer software, or combinations of both, and that the various illustrative components and steps have been described above generally in terms of their functionality in order to clearly illustrate this interchangeability of hardware and software. Whether such functionality is implemented as hardware or software depends upon the particular application and design constraints imposed on the implementation. Skilled artisans may implement the described functionality in varying ways for each particular application, but such implementation decisions should not be interpreted as causing a departure from the scope of the present invention.
The steps of a method or model described in connection with the embodiments disclosed herein may be embodied directly in hardware, in a software module executed by a processor, or in a combination of the two. A software module may reside in Random Access Memory (RAM), memory, Read Only Memory (ROM), electrically programmable ROM, electrically erasable programmable ROM, registers, hard disk, a removable disk, WD-ROM, or any other form of storage medium known in the art.
The previous description of the disclosed embodiments is provided to enable any person skilled in the art to make or use the present invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the generic principles defined herein may be applied to other embodiments without departing from the spirit or scope of the invention. Thus, the present invention is not intended to be limited to the embodiments shown herein but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.
Claims (6)
1. A method for calibrating parameters of an EPS model of an electric power steering system is characterized by comprising the following steps:
determining a plurality of EPS model parameters affecting a simulation characteristic curve of the EPS; the plurality of EPS model parameters includes: the motor torque characteristic parameter, the steering rack friction force parameter, the gear-rack transmission ratio parameter and the damping coefficient;
determining a calibration sequence of the EPS model parameters;
sequentially calibrating the EPS model parameters according to a calibration sequence so as to enable the simulation curve of the EPS to be close to a real characteristic curve;
the sequentially calibrating the EPS model parameters comprises:
adjusting the parameter value of the motor torque characteristic parameter to adjust the curvature and the amplitude of the simulation characteristic curve until a first condition is met; wherein the motor torque characteristic parameter value satisfying the first condition is a target motor torque characteristic parameter value;
adjusting the parameter value of the friction force parameter of the steering rack to adjust the cross section of the simulation characteristic curve until a second condition is met; the steering rack friction parameter value meeting the second condition is a target steering rack friction parameter value;
adjusting the parameter value of the gear-rack transmission ratio parameter to adjust the amplitude of the simulation characteristic curve until a third condition is met; the gear and rack transmission ratio parameter value meeting the third condition is a target gear and rack transmission ratio parameter value;
adjusting the parameter value of the damping coefficient to scale the simulation characteristic curve until a fourth condition is met; wherein the damping coefficient value satisfying the fourth condition is a target damping coefficient value;
and saving the target motor torque characteristic parameter value, the target steering rack friction force parameter value, the target gear-rack transmission ratio parameter value and the target damping coefficient value as calibrated parameter values.
2. The method of claim 1,
the first condition includes: the slope ratio of the simulated characteristic curve to the real characteristic curve is in a first ratio range, and the amplitude ratio of the simulated characteristic curve to the real characteristic curve is in a second ratio range;
the second condition includes: the difference value of the cross-sectional distances of the simulated characteristic curve and the real characteristic curve is within a preset cross-sectional distance range;
the third condition includes: the amplitude difference of the simulated characteristic curve and the real characteristic curve and the ratio of the amplitude of the real characteristic curve are within a third ratio range;
the fourth condition includes: the ratio of the slope of the simulated characteristic to the slope of the real characteristic is less than a first threshold, and the ratio of the amplitude of the simulated characteristic to the amplitude of the real characteristic is less than a second threshold.
3. The method of claim 2, wherein determining a plurality of EPS model parameters that affect a simulated characteristic of the EPS comprises:
determining candidate EPS model parameters influencing the simulation characteristic curve of the EPS;
and screening the plurality of EPS model parameters from the candidate EPS model parameters by using a control variable method.
4. The utility model provides an electric power steering system EPS model parameter calibration device which characterized in that includes:
a screening unit for:
determining a plurality of EPS model parameters affecting a simulation characteristic curve of the EPS; the plurality of EPS model parameters includes: the motor torque characteristic parameter, the steering rack friction force parameter, the gear-rack transmission ratio parameter and the damping coefficient;
determining a calibration sequence of the EPS model parameters;
a calibration unit for:
sequentially calibrating the EPS model parameters according to a calibration sequence so as to enable the simulation curve of the EPS to be close to a real characteristic curve;
in the aspect of sequentially calibrating the multiple EPS model parameters, the calibration unit is specifically configured to:
adjusting the parameter value of the motor torque characteristic parameter to adjust the curvature and the amplitude of the simulation characteristic curve until a first condition is met; wherein the motor torque characteristic parameter value satisfying the first condition is a target motor torque characteristic parameter value;
adjusting the parameter value of the friction force parameter of the steering rack to adjust the cross section of the simulation characteristic curve until a second condition is met; the steering rack friction parameter value meeting the second condition is a target steering rack friction parameter value;
adjusting the parameter value of the gear-rack transmission ratio parameter to adjust the amplitude of the simulation characteristic curve until a third condition is met; the gear and rack transmission ratio parameter value meeting the third condition is a target gear and rack transmission ratio parameter value;
adjusting the parameter value of the damping coefficient to scale the simulation characteristic curve until a fourth condition is met; wherein the damping coefficient value satisfying the fourth condition is a target damping coefficient value;
and saving the target motor torque characteristic parameter value, the target steering rack friction force parameter value, the target gear-rack transmission ratio parameter value and the target damping coefficient value as calibrated parameter values.
5. The apparatus of claim 4,
the first condition includes: the slope ratio of the simulated characteristic curve to the real characteristic curve is in a first ratio range, and the amplitude ratio of the simulated characteristic curve to the real characteristic curve is in a second ratio range;
the second condition includes: the difference value of the cross-sectional distances of the simulated characteristic curve and the real characteristic curve is within the range of the cross-sectional distances;
the third condition includes: the amplitude difference of the simulated characteristic curve and the real characteristic curve and the ratio of the amplitude of the real characteristic curve are within a third ratio range;
the fourth condition includes: the ratio of the slope of the simulated characteristic to the slope of the real characteristic is less than a first threshold, and the ratio of the amplitude of the simulated characteristic to the amplitude of the real characteristic is less than a second threshold.
6. An apparatus according to claim 5, wherein, in said determining a plurality of EPS model parameters affecting a simulated characteristic curve of an EPS, said screening unit is specifically configured to:
determining candidate EPS model parameters influencing the simulation characteristic curve of the EPS;
and screening the plurality of EPS model parameters from the candidate EPS model parameters by using a control variable method.
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