JP2011063130A - Control parameter adaptation device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a control parameter adaptation device improving reliability of adaptation data. <P>SOLUTION: The control parameter adaptation device includes a verification model having conditions where a specific problem, such as self-excited vibration of a steering wheel, is most likely to occur. The verification model is obtained by considering variations in dynamic characteristics among products, such as viscous frictions and Coulomb frictions of mechanical components in an electric power steering system. The operation of the electric power steering system is simulated by appending the adaptation data that are adapted control parameters, to the verification model. The validity of the adaptation data is verified based on the simulation result. This permits setting of the control parameters in consideration of the variations in the dynamic characteristics among the products when they are produced in large quantities. Consequently, the reliability of the adaptation data is enhanced. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a control parameter adapting apparatus that performs control parameter adapting work in a control system.

  For example, an electronic control device of a vehicle performs a calculation based on detection signals taken from various sensors that detect the state of each part of the vehicle, and controls the control system through the control of an actuator based on the calculation result. The electronic control device operates so that various systems such as an engine, an automatic transmission, and an electric power steering can exhibit optimum performance under various circumstances. The software executed by the electronic control device is structured to have flexibility by using parameters (constants). This makes it easy to change parameters of the same system and use them in another vehicle. This parameter is optimized through adaptation operations to obtain the desired system characteristics.

  For example, when an electric power steering system is mounted on a vehicle, conforming work, that is, adjustment of control parameters for various controls performed in the system is performed according to the characteristics of each vehicle and the steering feeling required by the vehicle manufacturer. . This fitting operation is repeatedly performed using a fitting device that operates according to a control parameter fitting program until a desired steering feeling is obtained in a vehicle equipped with the system (see, for example, Patent Document 1).

More specifically, after the compatible device is connected to the electronic control device of the electric power steering system via a communication line, control parameters are set in the compatible device. The control parameter is transferred to the electronic control device via the communication line and written to the storage device. Through the control of the motor by the electronic control device, it is possible to execute steering assistance reflecting the control parameters after setting. In this state, steering feeling is confirmed through actual traveling of the vehicle equipped with the system. Based on this actual steering feeling, the control parameter changing operation is performed again. A desired steering feeling can be obtained by setting the control parameter to an optimum value through repetition of such a procedure.
In addition, as described in Patent Document 2, for example, it has been conventionally proposed to evaluate the validity of a control parameter set by an adaptation operation by a simulation by software instead of evaluating it by an actual machine. That is, each element of the control system and the mechanical system of the control system is modeled, and the operation of the entire control system is simulated using these models. By using such a simulation technique, it is possible to confirm various vehicle characteristics such as steering characteristics in advance without performing an experiment with an actual machine.

JP 2005-178706 A JP 2008-197899 A

  However, the conventional adaptation work has the following problems. That is, when various control systems are mass-produced, variations occur between products in each mechanical element (dynamic characteristics such as viscous friction and Coulomb friction). The degree of variation of these elements, the combination of the variation elements, and the like are also different for each product. For this reason, there is a concern that various control parameters that have been optimal values at the stage of the adaptation work may not be optimal values for a specific product. Therefore, there is a possibility that the stability of the control system cannot be suitably secured in the specific product. This problem is assumed to be particularly noticeable in a control system including a number of mechanical elements such as viscous friction and Coulomb friction, such as the electric power steering system described above. For example, in an electric power steering system, there is a concern that abnormal noise or self-excited vibration of a steering wheel may occur due to variations in mechanical elements between products.

  Note that, even when a set control parameter (adapted value) is evaluated using a simulation technique, the evaluation procedure and contents follow the procedure and contents when the evaluation is performed using an actual machine. For this reason, when a product is mass-produced, there is a similar concern about the occurrence of problems due to variations in mechanical elements. As described above, there is still room for improvement in terms of the reliability of the matching data, which is the optimized control parameter.

  The present invention has been made to solve the above problems, and an object of the present invention is to provide a control parameter adapting apparatus capable of improving the reliability of the conforming data.

  The invention according to claim 1 is a control parameter adapting device that adapts the control parameters of the control system so that the control system including the mechanical components that operate through the control by the electronic control device exhibits the required performance. Based on the result of the simulation, the operation of the control system is simulated by providing calibration data, which is an adapted control parameter, to a simulation model that takes into account variations between products of dynamic characteristics of the control system. The gist of the invention is that it comprises a verification means for verifying the validity of the matching data.

  According to the present invention, by simulating the operation of the control system using a simulation model that takes into account the variation in dynamic characteristics of the control system between products, the variation in dynamic characteristics between products during mass production. It is possible to set control parameters in consideration of the above. For this reason, the reliability of the adaptation data which is the adapted control parameter is improved.

  According to a second aspect of the present invention, in the control parameter adaptation device according to the first aspect, the simulation model has the most specific problem by taking into account all variations in dynamic characteristics of the control system among products. The gist of the present invention is to have conditions that are likely to occur.

According to the present invention, the reliability of matching data can be further improved through simulation using a simulation model having a condition in which a specific problem is most likely to occur.
According to a third aspect of the present invention, in the control parameter adaptation device according to the first or second aspect, the dynamic characteristics of the control system include viscous friction and Coulomb friction of the mechanical component. It becomes the gist.

  Viscous friction and Coulomb friction greatly affect the stability of the control system. These viscous friction and Coulomb friction not only vary among products, but also change over time. For this reason, as in the present invention, the operation of the control system is simulated using a simulation model that takes into account the variation between the viscous friction and the Coulomb friction between products. Accuracy is increased. The reliability of conforming data is also increased.

  The gist of the invention described in claim 4 is the control parameter adaptation device according to any one of claims 1 to 3, further comprising notification means for notifying a verification result by the verification means. And

  According to the present invention, it is possible to perform the adaptation work based on the verification result. For example, the conforming operator can recognize whether or not the control parameter he / she has adapted is appropriate, so that it is easy to adjust the control parameter again as necessary. In this way, the efficiency of the adaptation work can be improved.

  The gist of the invention according to claim 5 is the control parameter adaptation device according to claim 4, wherein the notification by the notification means includes guidance regarding control parameter adaptation.

According to the present invention, a conforming operator can perform conforming work according to the guidance. For this reason, the efficiency of the adaptation work is improved.
The gist of the invention described in claim 6 is the control parameter adapting apparatus according to any one of claims 1 to 5, wherein the control system is an electric power steering system.

  The electric power steering system has many mechanical components and is complicated. The control parameter adapting device according to any one of claims 1 to 5 is suitable for the adapting operation of such a system.

  According to the present invention, it is possible to adapt the control parameters in consideration of variations in the mechanical elements of the control system that occur during mass production. For this reason, the reliability of the adaptation data can be improved.

The block diagram which shows the aspect of use of a suitable apparatus. (A) is a block diagram which shows the structure of a compatible apparatus, (b) is a front view of the screen which shows the example of a display of a display apparatus. The block diagram which shows the outline of the model of an electric power steering system. The block diagram of the simulation model for verification (base). (A) is a block diagram showing each element of the equation of motion set in modeling the handle, (b) is a block diagram showing a model of the handle obtained based on the equation of motion of the handle. The block diagram which shows each element of a mechanical system model. The block diagram of a torque control part model. The block diagram of a current control part model. The block diagram of the model for verification which shows a load state. The block diagram of the model for verification. The graph which shows the map of the basic assist control part for self-excited vibration verification. (A) is a graph showing the gain diagram of the Bode diagram, and (b) is a graph showing the phase diagram of the Bode diagram. The flowchart which shows the procedure of a verification process.

Hereinafter, an embodiment in which the present invention is embodied in a control parameter adapting device used for controlling an electric power steering system will be described with reference to FIGS.
First, a schematic configuration of an electric power steering system that is a target of conforming work in this example will be described.

  As shown in FIG. 1, in the electric power steering system 1, a steering shaft 3 that rotates integrally with a handle 2 (steering wheel) is connected in order of a column shaft 8, an intermediate shaft 9, and a pinion shaft 10 from the handle 2 side. Become. The pinion shaft 10 is meshed with a rack portion 5a of a rack shaft 5 provided orthogonal to the pinion shaft 10. The rotation of the steering shaft 3 accompanying the steering operation is converted into a reciprocating linear motion of the rack shaft 5 by the rack and pinion mechanism 4 including the pinion shaft 10 and the rack portion 5a. The reciprocating linear motion is transmitted to a knuckle arm (not shown) via tie rods 11 connected to both ends of the rack shaft 5, thereby changing the steering angle of the steered wheels 12.

  In addition, the electric power steering system 1 includes a steering force assist device (power assist unit) 13 that applies an assist force for assisting a steering operation to the steering system, and an electronic control device that controls the operation of the steering force assist device 13 ( ECU) 14.

  A motor 15 that is a drive source of the steering force assisting device 13 is operatively connected to the column shaft 8 via a speed reduction mechanism 16 including a worm and a worm wheel. The rotational force of the motor 15 is decelerated by the speed reduction mechanism 16 and this is transmitted as an assist force to the steering system, more precisely to the column shaft 8. The electronic control unit 14 controls the assist force as follows. That is, the electronic control unit 14 acquires the vehicle speed V through the vehicle speed sensor 17 provided on the steered wheels 12 and the like. Further, the electronic control unit 14 acquires the steering torque τ applied to the handle 2 through the torque sensor 18 provided on the column shaft 8. The electronic control unit 14 calculates a target assist force based on the vehicle speed V and the steering torque τ, and performs power feeding control of the motor 15 so as to generate the calculated target assist force. The assist force applied to the steering system is controlled through the power supply control of the motor 15.

  In this example, although it is assumed that a motor with a DC brush is used as the motor 15, a brushless motor may be used. In this example, the torque sensor 18 is of a type that detects the steering torque τ based on the torsion angle of a torsion bar (not shown) provided in the middle of the column shaft 8. That is, the column shaft 8 is composed of two shafts connected to both ends of the torsion bar.

<Outline of compatible device>
In the electric power steering system configured as described above, control parameters used in the electronic control device are set to optimum values so that the system can exhibit desired performance. As shown in FIG. 1, this adaptation operation is performed using an adaptation device 21 that operates according to a control parameter adaptation program. The control parameter set in the adapting device 21 is transferred to the electronic control device 14 through the communication line 22 after a simulation is performed on the device and its validity is confirmed. The communication line 22 is detachable from the electronic control device 14 and the adapting device 21. It should be noted that on the screen of the display device, which will be described later, provided in the adapting device 21, various control parameters (adaptation data) to be subjected to the adapting work, a map in which these parameters are graphed (conformity map), and control parameters by simulation The verification result of the validity of is displayed. The operator performs the adaptation work while visually observing the display on these screens.

<Configuration of compatible device>
Next, the configuration of the adaptation device 21 will be described. As shown in FIG. 2A, the adaptation device 21 includes a control device 31, a display device 32, an auxiliary storage device 33, and an input device 34.

  As the auxiliary storage device 33, a hard disk device, a nonvolatile memory, or the like is employed. The auxiliary storage device 33 stores various control programs executed by the control device 31, data, and the like. The data stored in the auxiliary storage device 33 includes, for example, the specifications of the electric power steering system 1 and the vehicle on which it is mounted, the mathematical model 51 of the electric power steering system 1, and the like. The model 51 is generated through software execution by the adaptation device 21. The model 51 will be described in detail later.

  As the input device 34, a keyboard 35, a mouse 36, and the like are employed. Through the input device 34, various functions of the adapting device 21 are executed, and various data are input.

  The control device 31 includes a CPU (central processing unit) 41, a main storage device 42, a LAN (local area network) interface unit 43, a display control unit 44, an auxiliary storage device interface unit 45, and an input device interface unit. 46 and an interface unit 47 for connection with the electronic control unit 14, and these are connected to each other through a bus 48. The main storage device 42 is composed of a volatile memory or the like.

  The display control unit 44 is connected to a display device 32 such as a cathode ray tube (CRT) and a liquid crystal display. The display control unit 44 controls display on the display device 32 based on a display command from the CPU 41.

  The auxiliary storage device 33 is connected to the interface unit 45 for the auxiliary storage device. An input device 34 such as a keyboard 35 and a mouse 36 is connected to the interface unit 46 for the input device. The electronic control unit 14 is connected to the interface unit 47 for connection with the electronic control unit 14 via the communication line 22. The adapting device 21 can be connected to the LAN 49 via the LAN interface unit 43.

  The adapting device 21 functions as a control parameter adapting device of the electric power steering system when the CPU 41 executes a program read from the auxiliary storage device 33 to the main storage device 42. In addition, the adapting device 21 is connected to the electronic control device 14 via the communication line 22 to read various control parameters stored in the electronic control device 14 or to adjust the control parameters after adjustment that has been optimized. Or the like can be transferred to the electronic control unit 14.

<Functions of compatible equipment>
Next, various functions of the adaptive device 21 will be described. Each function of the adaptive device 21 is realized by various arithmetic functions based on various programs stored in the auxiliary storage device 33.

  The adapting device 21 (precisely, the CPU 41) has an initial design function for performing initial setting of control parameters for various controls in accordance with the vehicle based on the vehicle specifications and system specifications stored in the auxiliary storage device 33. ing. And the adaptation apparatus 21 adjusts a steering feeling with respect to this initial design. That is, the adapting device 21 has a control parameter changing function for changing (adjusting) various control parameters that are initially set so that a desired steering feeling is realized. The change of the control parameter is performed in response to input from the input device 34 such as the keyboard 35 and the mouse 36. The input control parameters are temporarily stored in the main storage device 42.

  The adaptation device 21 has a simulation function for simulating the operation of the electric power steering system 1 including calculation of a current command value by the electronic control device 14 based on the set control parameter, and based on the result of the simulation. It has a verification function that verifies the presence or absence of a situation where the system becomes unstable (presence of instability). The simulation is performed by using a model 51 of the electric power steering system 1 (more precisely, a verification model 71 described later) stored in the auxiliary storage device 33. Then, the matching device 21 displays the verification result by the simulation using the model 51 on the screen of the display device 32 through the display control unit 44. When the adapting device 21 determines that there is a possibility that the system will become unstable, the display device 32 provides the contents of the unstable situation and a countermeasure for avoiding the occurrence of the situation. It has a guidance function to notify through such as.

  The adapting device 21 transfers the set control parameter group stored in the main storage device 42 to the electronic control device 14 in order to reflect the result of the adapting operation, that is, the set control parameter in the electronic control device 14. . By storing the control parameters after the setting in the electronic control device 14, it becomes possible to execute the steering assist reflecting the control parameters after the setting through the control of the motor 15 by the electronic control device 14.

<Screen display of display device>
Here, the screen display of the display device 32 will be described. As shown in FIG. 2B, on the screen of the display device 32, various control parameters (conformity data) to be subjected to the conforming work, a map in which these parameters are graphed (conformance map), and control by simulation. The verification result of parameter validity is displayed. That is, the screen of the display device 32 is formed by dividing the area where these are displayed. In the figure, on the left side of the screen, a first display screen 32a is formed on which control parameters corresponding to specific matching items such as assist torque are displayed. Similarly, in the center of the screen, a second display screen 32b on which a map graphed based on the control parameters displayed on the first display screen 32a is displayed is formed. Similarly, on the right side of the screen, a third display screen 32c on which the verification result of the control parameter by simulation is displayed is formed. Note that the number of display screens, items to be displayed on the screen, and the like can be appropriately changed through the input device 34.

  A verification button Bgui is provided at the top of the screen of the display device 32. When the verification button Bgui is pressed through the input device 34, execution of the control parameter verification process by simulation is started. The verification button Bgui is a graphical representation of the function as a push button.

<Schematic configuration of system model>
Next, the model 51 of the electric power steering system 1 will be described. In this example, all the components of the electric power steering system 1 are modeled. That is, as shown in FIG. 3, the model 51 includes a mechanical system model 52 in which all mechanical elements of the electric power steering system 1 are modeled, and steering assist control executed by the electronic control unit 14. It consists of a control system model 53 in which all control logics are modeled.

  The mechanical system model 52 includes all the mechanical configurations of the electric power steering system 1 such as the handle 2, the steering shaft 3 (the column shaft 8, the intermediate shaft 9 and the pinion shaft 10), the rack shaft 5, and the torque sensor 18. These are extracted and modeled. The control system model 53 is a model of all control logic related to the control of the motor 15 executed by the electronic control unit 14. The output in the control system model 53 is the output shaft 15 a of the motor 15.

  The model 51 shown in the figure serves as the basis (base) of the verification model 71 used when verifying the validity of the set control parameter. The verification model 71 will be described in detail later.

<Operation of system model>
Next, the operation of the model 51 of the electric power steering system 1 described above will be described. As shown in FIG. 4, the mechanical system model 52 is provided with a substitute signal for the steering torque signal generated by the signal generator 52b as the steering torque τ. The mechanical system model 52 is calculated based on the torsion bar torque Ta generated in the torsion bar according to the steering torque τ, the rotation angle (electrical angle) θ of the motor 15 detected through a rotation angle sensor (not shown), and the rotation angle θ. The rotation speed ω of the motor 15 is calculated, and these calculation results are output to the control system model 53. The mechanical system model 52 calculates the detected displacement Xra of the rack shaft 5 and the displacement speed dXra of the rack shaft 5 obtained by differentiating the displacement Xra. In the mechanical system model 52, a load L from a mechanical load acting on the rack shaft 5 is fed back. The load L is determined according to the values of the displacement Xra and the displacement speed dXra of the rack shaft 5. In this example, the load device 52 a is set between the tie rod 11 and the steered wheels 12 connected to both ends of the rack shaft 5.

  Note that the parameters (constants) such as Coulomb friction (dynamic friction) and viscous friction of the mechanical system model 52 vary among the products when the electric power steering system 1 is mass-produced. These parameters also change over time. Therefore, when verifying the validity of the control parameters to be adapted through the fitting operation, it is performed in consideration of variations between products of mechanical elements such as Coulomb friction and viscous friction, or changes over time. That is, the validity of the adapted control parameter is verified by using the verification model 71 in consideration of the variation of these mechanical elements. The verification model 71 is based on data of lower limit values that have the strictest conditions for various assumed problems (for example, self-excited vibration of the steering wheel) as values such as Coulomb friction (dynamic friction) and viscous friction. (To be precise, it is generated by inputting to the mechanical system model 52). Various mechanical elements of the mechanical system model 52 will be described in detail later.

  As shown in FIG. 4, the control system model 53 includes a torque control unit 54 and a current control unit 55. The torque control unit 54 calculates a current command value I * that is a command value of assist torque (current) for the motor 15 based on information such as the steering torque τ, the rotation angle θ of the motor 15, and the vehicle speed V. The current control unit 55 supplies the assist torque (current) as commanded from the torque control unit 54 to the motor 15 based on the assist torque command value (current command value I *) calculated by the torque control unit 54. Energization control is executed as much as possible. The current control unit 55 relates to the current control of the motor 15 based on the current command value I * acquired through the torque control unit 54, the rotation angle θ and the rotation speed ω of the motor 15 acquired through the mechanical system model 52. Perform various operations.

  In the adaptation work, the value (adaptation value) of the control parameter of the torque control unit 54 is changed. In other words, the control parameters suitable for the verification model of the electric power steering system 1 described later are given, and the validity is verified.

<Details of mechanical model>
Next, the generation process of the mechanical system model 52 will be described in detail. The mechanical system model 52 is a system composed of various mechanical elements such as a spring, inertia (mass, inertia), and friction (viscous friction, Coulomb friction), and these elements are constituted by basic equations of motion. A mechanical system model 52 is generated based on each equation of motion.

  For example, modeling of the handle 2 is performed as follows. That is, first, as shown in FIG. 5A, an equation of motion is established in consideration of torque (inertia torque, steering torque, torsional torque due to rigidity, friction torque) acting on the handle 2. The equation of motion is obtained based on the relationship between the handle 2 and the upper portion of the column shaft 8 (in the drawing, “column upper portion”), as shown in FIG.

  Then, a simulation model as shown in FIG. 5B is generated based on the equation of motion. That is, in this model, the difference between the handle angle θst, which is the operation angle of the handle 2, and the rotation angle θcu of the upper portion of the column shaft 8 is multiplied by the torque coefficient Kst to thereby twist due to the rigidity of the upper portion of the column shaft 8. Calculate the torque. Then, the inertia torque of the handle 2 is calculated by subtracting the torsion torque, the viscous friction of the handle 2 and the Coulomb friction from the steering torque Tst input through the handle 2. Then, the angular acceleration of the handle 2 is calculated based on the calculated inertia torque and the inertia Jst of the handle 2, and the angular velocity of the handle 2 is calculated by integrating the angular acceleration. In the model, the above-described viscous friction of the handle 2 is calculated by multiplying the angular velocity of the handle 2 by the viscous friction coefficient Cst. Further, the above-described coulomb friction of the handle 2 is calculated by multiplying the angular velocity of the handle 2 by the Coulomb friction coefficient Rst. Further, in the model, the handle angle θst of the handle 2 is calculated by integrating the calculated angular velocity. As described above, the model of the handle 2 shown in FIG. 5B reflects the equation of motion shown in FIG.

  In the mechanical components of the electric power steering system 1, the parts other than the handle 2, that is, the upper and lower parts of the column shaft 8, the steering force assisting device 13 (motor), the upper and lower parts of the intermediate shaft 9, and the pinion The shaft 10 (pinion) and the rack shaft 5 (rack 5a) are modeled similarly to the handle 2. Then, an overall simulation model (mechanical system model 52) of the electric power steering system 1 is constructed from these models.

<Mechanical model parameters>
Next, each element of the mechanical system model 52 will be described. Each element of the mechanical system model 52 is defined and set as follows.

  That is, as shown in FIG. 6, the model of the handle 2 includes the steering torque Tst, the inertia Jst, the viscous friction (viscous friction coefficient Cst), the Coulomb friction (Coulomb friction coefficient Rst), and the handle 2 It is defined and set by the rigidity (torque coefficient Kst) between the upper part of the column shaft 8.

  The model of the upper part of the column shaft 8 is defined and set by inertia Jcu, viscous friction (coefficient of friction friction Ccu), Coulomb friction (Coulomb friction coefficient Rcu), and torsion bar rigidity (torque coefficient Ktb).

  The model below the column shaft 8 is defined by inertia Jcl, viscous friction (coefficient of friction Ccl), Coulomb friction (Coulomb friction coefficient Rcl), and rigidity of the joint with the intermediate shaft 9 (torque coefficient Kj). Is set.

  The model of the steering force assisting device 13 (motor unit) includes worm gear inertia Jw, motor shaft inertia Jms, viscous friction of the motor 15 portion (viscosity friction coefficient Cm), coulomb friction of the motor 15 portion (Coulomb friction coefficient Rm), It is defined and set by the rigidity (torque coefficient Kwm) of the joint between the worm gear and the motor shaft and the motor torque Tmo.

  The upper model of the intermediate shaft 9 is defined and set by inertia Jiu, viscous friction (coefficient of viscous friction Ciu), coulomb friction (coulomb friction coefficient Riu), and rigidity of the intermediate shaft 9 (torque coefficient Ki). The

  The model below the intermediate shaft 9 includes inertia Jil, viscous friction (viscous friction coefficient Cil), Coulomb friction (Coulomb friction coefficient Ril), and rigidity between the intermediate shaft 9 and the pinion shaft 10 (torque coefficient Kip). Defined and set by.

  The model of the pinion shaft 10 (pinion part) is defined and set by inertia Jp, viscous friction (viscous friction coefficient Cp), and Coulomb friction (Coulomb friction coefficient Rp).

  The model of the rack shaft 5 (rack 5a) includes a mass Mra of the rack shaft 5, viscous friction (viscosity coefficient of friction Cra), Coulomb friction (coulomb friction coefficient Rra), rack guide friction (friction coefficient Frg), and spring load. It is defined and set by the rigidity (torque coefficient Ksp) of the apparatus.

  Among these mechanical elements, the viscous friction and Coulomb friction of each part vary among products. In addition, the values of these decrease with time. For this reason, in the verification model 71 described later, these values are set to values that are the strictest conditions for a specific problem that may occur in the electric power steering system 1. For example, in the verification model 71 when verifying the self-excited vibration of the handle 2, lower limit values in the range of values that can be taken are set as the values of the viscous friction and the Coulomb friction of each part. Self-excited vibration refers to a phenomenon in which vibration is caused by a phenomenon unrelated to vibration.

<Torque controller model>
Next, the model of the torque control unit 54 will be described in detail.
As shown in FIG. 7, the model of the torque control unit 54 includes a basic assist control unit 61 and a compensation control system 62.

  The basic assist control unit 61 calculates a basic assist current command value Ia * according to the steering torque τ (torsion bar torque Ta) and the vehicle speed V subjected to the phase compensation processing by the phase compensation unit 61a. The basic assist current command value Ia * is a basic component of the finally generated current command value I *. The basic assist current command value Ia * is calculated as a value having a larger absolute value as the steering torque τ (more precisely, its absolute value) is larger and as the vehicle speed V is smaller. The basic assist control unit 61 calculates a basic assist current command value Ia * based on the basic assist torque map. The assist torque map is a characteristic map in which the vehicle speed V, the steering torque τ (torsion bar torque Ta), and the basic assist current command value Ia * are associated with each other. During the adaptation work, the steering torque τ (torsion bar torque Ta) that defines the assist torque map and the basic assist current command value Ia * are adapted as the adaptation data.

  The compensation control system 62 includes a differential operation unit 62a and a torque differential control unit 62b. The differential calculation unit 62a calculates a differential value T ′ of the steering torque τ (torsion bar torque Ta). The torque differential control unit 62b calculates a correction current command value Ib * that is a compensation component of the steering torque τ based on the differential value T ′ calculated by the differential calculation unit 62a. The torque differentiation control unit 62b calculates a correction current command value Ib * based on the correction torque map. The correction torque map is a characteristic map in which the differential value T ′ of the steering torque τ (torsion bar torque Ta) and the correction current command value Ib * are associated with each other. The correction current command value Ib * is calculated so as to compensate for the inertia, viscosity, and handle 2 returnability unique to the electric power steering system 1. At the time of the adaptation work, the differential value T ′ of the steering torque τ that defines the correction torque map and the correction current command value Ib * are adapted as the adaptation data.

  The addition value of the basic assist current command value Ia * calculated by the basic assist control unit 61 and the corrected current command value Ib * calculated by the torque differentiation control unit 62b is the final current command value I *. Calculated.

<Current control unit model>
Next, the model of the current control unit 55 will be described in detail.
As shown in FIG. 8, the model of the current control unit 55 includes a functional part realized by CPU computation (software) and a functional part realized by hardware such as the motor 15.

  The current control unit 55 (software) executes PI calculation based on the current command value I * generated by the torque control unit 54. That is, the current control unit 55 calculates a difference ΔI between the current command value I * and the actual current I of the motor 15. Then, the current control unit 55 adds the value obtained by multiplying the integral value of the value of the difference ΔI by a predetermined integral gain and the value obtained by multiplying the value of the difference ΔI by a predetermined proportional gain to apply to the motor 15. The voltage V * (voltage command value) is calculated. The current control unit 55 applies the calculated voltage V * to the motor 15 through a motor drive circuit (not shown). The motor 15 generates a motor torque Tmo corresponding to a value obtained by multiplying the motor impedance, the torque constant Kt, and the rotational speed ω by the counter electromotive voltage constant Ke. In this example, a motor with a DC brush is assumed as the motor 15.

<Validation data verification process>
Next, a verification process for verifying the validity of a parameter adapted using the adaptation device 21 configured as described above will be described. In this example, as a problem that may occur in the electric power steering system 1, a case will be described in which the presence or absence of occurrence of self-excited vibration of the handle 2 is verified. The following factors can be considered as factors causing the self-excited vibration of the handle 2. That is, the control system (actual machine or model) that evaluates each parameter that is adapted through the adaptation device 21 is such that all values of mechanical elements such as friction (viscous friction and Coulomb friction) are lower limit values, etc. When it is not the worst condition, problems such as self-excited vibration do not occur. However, for example, when a product having the worst condition such that all values of mechanical elements such as friction are lower limit values is produced, the assist gradient of the basic assist torque map in the basic assist control unit 61 is, for example, If it is too large, the control system may become unstable and self-excited vibration may occur. In this case, the parameter related to the occurrence of self-excited vibration is the assist gradient of the basic assist torque map that the basic assist control unit 61 has. Therefore, in order to suppress the occurrence of self-excited vibration, whether or not the control system has become unstable when the friction (viscous friction and Coulomb friction) of each element of the mechanical system is set to the lower limit value. Verification is required.

  The verification is performed using a self-excited vibration verification model 71 based on the model 51 of the electric power steering system 1 described above. The verification model 71 basically has the same configuration as the model 51 described above. Therefore, the same components as those of the model 51 are denoted by the same reference numerals and detailed description thereof is omitted.

  In the verification model 71, the coulomb friction and viscous friction values of each element of the mechanical system model 52 described above are set to lower limit values where self-excited vibration is most likely to occur. Further, as shown in FIG. 9, as load conditions, both ends of the rack shaft 5 are free ends (free), and the handle 2 is fixed. Furthermore, as shown in FIG. 10, the verification model 71 is a model that constitutes a torque open loop. That is, the torsion bar torque Ta detected by the torque sensor 18 is supplied not to the torque control unit 54 but to the self-excited vibration determination unit 72. Instead of the torsion bar torque Ta, the torque control unit 54 is supplied with a SinSweep signal Tin (sine wave signal). The SinSweep signal Tin is also supplied to the self-excited vibration determination unit 72. Since the most severe vehicle speed condition for self-excited vibration is 0 km / h, the vehicle speed V is set to 0 km / h.

  In the verification model 71, the basic assist torque map of the basic assist control unit 61 is a self-excited vibration verification map. That is, as shown in FIG. 11, the map data (the torsion bar torque Ta and the basic assist are set so that the map has the largest assist gradient in the basic assist torque map adapted through the adaptation work and passes through the origin. Current command value Ia *) is set.

  The self-excited vibration determination unit 72 determines the stability of the system based on the torsion bar torque Ta and the SinSweep signal Tin. That is, the self-excited vibration determination unit 72 calculates a transfer function G (s) between the SinSweep signal Tin that is an input signal and the torsion bar torque Ta that is an output signal. The transfer function G (s) is represented by the ratio of the Laplace transform between the output signal and the input signal. When the Laplace transform of the torsion bar torque Ta (signal) is Ta (s) and the Laplace transform of the SinSweeep signal Tin is Tin (s), the transfer function G (s) is expressed as follows.

G (s) = Ta (s) / Tin (s)
The Bode diagram representing the frequency characteristic of the transfer function G (s) is shown by a combination of the gain diagram shown in FIG. 12 (a) and the phase diagram shown in FIG. 12 (b). The gain diagram is a graph in which logarithmic values of gain (dB) for each frequency (Hz) are plotted on the vertical axis with the logarithmic frequency axis as the horizontal axis. The phase diagram is a graph showing the relationship between frequency and phase. In the phase diagram, the frequency is represented by a logarithmic axis as in the gain diagram. Used in conjunction with a gain diagram to evaluate the amount of phase displacement with respect to frequency.

Here, generally, gain margin gm and phase margin φm are known as measures (references) related to the stability of the system.
As shown in FIG. 12A, the gain margin gm indicates how much margin is available up to 0 dB. In other words, the gain margin gm indicates how much dB the gain has from 0 dB when the phase is −180 °. It can also be said that the gain at the frequency where the phase is inverted is shown.

As shown in FIG. 12B, the phase margin φm indicates how many margins the phase has by −180 ° (that is, before inversion) when the gain is 0 db.
It is known that the larger the gain margin gm and the phase margin φm are, the more stable the stability is and the less unstable the parameter variation. Usually, it is preferable that the gain margin gm is 10 db or more and the phase margin φm is 40 ° or more.

  Then, the self-excited vibration determination unit 72 obtains the gain margin gm and the phase margin φm using the Bode diagram of the transfer function G (s), and determines whether or not these values are ensured by a predetermined value or more. Determine if it occurs.

  When it is determined that the following two conditional expressions (A) and (B) are satisfied, the self-excited vibration determination unit 72 determines that the system is stable. If it is determined that any of the conditions is not satisfied, the system is determined to be unstable.

・ Gain margin gm ≧ gain margin determination threshold gmh (A)
・ Phase margin φm ≧ phase margin determination threshold φmh (B)
The gain margin determination threshold gmh is a value that serves as one reference for determining the stability of the system. In this example, the gain margin determination threshold gmh is 10 dB.

The phase margin determination threshold φmh is a value serving as one reference for determining the stability of the system. In this example, the gain margin determination threshold gmh is 40 degrees.
<Verification processing procedure>
Next, the procedure of parameter verification processing by the adapting device 21 will be described with reference to the flowchart of FIG. The flowchart is executed by the CPU 41 in accordance with various control programs stored in the auxiliary storage device 33.

The verification process is executed when a verification button Bgui provided on the screen of the display device 32 is pressed through the input device 34.
When detecting that the verification button Bgui has been pressed, the CPU 41 reads the verification model 71 stored in the auxiliary storage device 33 (step S101). Next, the CPU 41 sets a control parameter (adapted value) adapted through the adapting work in the verification model 71 (step S102), and executes a simulation (step S103). That is, the SinSweep signal Tin is applied to the torque control unit 54 (model). The CPU 41 calculates a transfer function G (s) between the SinSweep signal Tin that is an input signal and the torsion bar torque Ta that is an output signal, and evaluates the stability of the system based on the transfer function G (s), that is, The presence / absence of occurrence of a situation in which the system becomes unstable (presence of instability) is determined (step S104).

  When it is determined that the above two conditional expressions (A) and (B) are satisfied, the CPU 41 determines that there is no occurrence of a situation in which the system becomes unstable (NO in step S104). Is displayed on the third display screen 32c (step S105), and the process ends.

  On the other hand, if the CPU 41 determines that at least one of the two conditional expressions (A) and (B) is not satisfied, there is a possibility that the system may become unstable. (YES in step S104), a message to that effect is displayed on the screen of the display device 32, more precisely, on the third display screen 32c (step S106), and the process ends.

  For example, the following warning text is displayed as the warning content. In other words, if the warning is the result of verification related to self-excited vibration, as shown in FIG. 2 (b), “Warning! This self-excited vibration” can occur during mass production. There is sex. Is displayed on the third display screen 32c indicating the content of the situation where the system becomes unstable. As shown in the figure, not only the warning text but also the countermeasures such as which control parameter should be set to display the unstable situation will be displayed. It may be. For example, the guidance “Please review the map shape so that the assist gradient is less than ◯ Nm / Nm” is displayed on the third display screen 32c. Also, these warnings and guidance can be made by hearing. In this case, the adapting device 21 is provided with a notification means such as a speaker. Information indicating the contents of the warning and guidance is stored in advance in the auxiliary storage device 33.

  If there are a plurality of verification targets related to instability, it is also possible to perform verification by simulating each verification simulation model continuously. In this case, steps S101 to S106 in the flowchart of FIG. 13 are automatically repeated. A simulation model for verification is created for each problem that is likely to occur in the electric power steering system 1, and these models are stored in advance in the auxiliary storage device 33.

<Effect of Embodiment>
Therefore, according to the present embodiment, the following effects can be obtained.
(1) Electric power is provided by applying conformity data, which is an adapted control parameter, to a verification model 71 that takes into account variations between products in dynamic characteristics (viscous friction and coulomb friction) of the electric power steering system 1. The operation of the steering system 1 is simulated. And the validity of the said fitting data was verified based on the result of the said simulation. For this reason, control parameters can be set in consideration of variations in dynamic characteristics between products during mass production. Therefore, the reliability of the adaptation data that is the adapted control parameter is increased.

  (2) The verification model 71 has a condition in which a specific problem (for example, self-excited vibration of the steering wheel 2) is most likely to occur by taking into account all variations in the dynamic characteristics of the electric power steering system 1 between products. Do it. For this reason, the reliability of the fitting data is further improved through simulation using a simulation model having conditions where the specific problem is most likely to occur.

  In addition, by performing the calibration work through simulation that assumes the worst-case condition of the system (the situation in which the system becomes unstable), the system is caused by variations in dynamic characteristics between products or changes in values over time. It is possible to suppress a decrease in stability. In the electric power steering system 1, problems such as the occurrence of self-excited vibration of the steering wheel 2 due to an excessive control amount are suppressed from occurring in the market after mass production.

  (3) Examples of dynamic characteristics of the electric power steering system 1 include viscous friction and Coulomb friction of mechanical components of the system. These viscous friction and Coulomb friction greatly affect the stability of the electric power steering system 1. These viscous friction and Coulomb friction not only vary among products, but also change over time. For this reason, the validity of the conformity data is simulated by simulating the operation of the electric power steering system 1 using a simulation model that takes into account variations between products of the viscous friction and the Coulomb friction as in this example. The accuracy of the determination is improved. The reliability of conforming data is also increased.

  (4) The verification result of the conformity data by simulation is notified (displayed) through the display device 32. According to this configuration, it is possible to perform the adaptation work based on the verification result. For example, the conforming operator can recognize whether or not the control parameter he / she has adapted is appropriate, so that it is easy to adjust the control parameter again as necessary. Therefore, the efficiency of the adaptation work is achieved.

  (5) When it is determined that the adapted control parameter is not valid, the display device 32 is used to notify the guidance regarding the adaptation of the control parameter. The conforming worker can perform the conforming operation again according to the guidance. For this reason, the efficiency of the adaptation work is improved.

(6) The electric power steering system 1 is complicated with many mechanical components. The adapting device 21 of this example is suitable for the adapting operation of such a system.
(7) Although it is possible to evaluate the actual vehicle so as to cover all the worst conditions, in this case, the control reflected in all the possible problems and all the factors that cause the problems. It is necessary to prepare a system. However, this is not realistic from the viewpoint of cost and man-hours. In this example, by using the simulation technique, it is possible to comprehensively evaluate all the worst conditions while reducing costs and man-hours.

<Other embodiments>
The embodiment described above may be modified as follows.
In this example, guidance is provided only on the screen of the display device 32 in order to eliminate the occurrence of the unstable situation only when a verification result indicating that the situation where the system becomes unstable may occur is obtained. However, guidance may be displayed during normal adaptation work.

  Various types of programs including compatible programs stored in the auxiliary storage device 33 can be stored in a storage medium such as a CDROM and distributed. The program can also be distributed through a network such as the Internet.

  -Data may be shared by connecting to an external database etc. via LAN49, and the data of every vehicle or other conforming workers may be used. It is also possible to construct a vehicle development system that shares the progress of processes such as development and efficiently shares work.

  -In this example, the electric power steering system 1 was applied to the conforming work, but other than the vehicle engine, the brake, the VGRS (variable gear ratio steering), the suspension, the coupling of the four-wheel drive vehicle (driving force transmission device), etc. It may be applied to the adjustment work of the control system. Further, the present invention can be applied not only to a control system mounted on a vehicle.

  In this example, in the mechanical model 52 for verification, all values of mechanical elements such as friction of each component are set as the lower limit value, but the lower limit value is set only for an appropriate minimum element. May be set to evaluate the fitness value. Even in this case, the adjustment work of the control parameters and the verification of the matched parameters can be performed in consideration of variations in mechanical elements such as friction between products. Therefore, the reliability of the conforming value (conforming data) can be improved. In this case, it is sufficient to extract only appropriate elements for modeling.

<Other technical ideas>
Next, the technical idea that can be grasped from the above embodiment will be added below.
In an adapting device that adapts the control parameters of the control system so that the control system including the mechanical components that operate through control by the electronic control device exhibits the required performance.
The control system is provided with conformity data that is a conformed control parameter to a simulation model having a condition in which a specific problem is most likely to occur in consideration of variations in dynamic characteristics of the control system between products. And a verification parameter matching device comprising verification means for verifying the validity of the calibration data based on the result of the simulation.

  DESCRIPTION OF SYMBOLS 1 ... Electric power steering system (control system), 14 ... Electronic control unit, 21 ... Adaptation apparatus, 32 ... Display apparatus (notification means), 41 ... CPU (verification means), 71 ... Verification model (Verification simulation model) ).

Claims (6)

In a control parameter adapting device that adapts the control parameters of the control system so that the control system including mechanical components that operate through control by the electronic control device exhibits the required performance.
Based on the result of the simulation, the operation of the control system is simulated by providing calibration data, which is an adapted control parameter, to a simulation model that takes into account variations between products of dynamic characteristics of the control system. A control parameter adaptation device comprising verification means for verifying the validity of the adaptation data. In the control parameter adaptation device according to claim 1,
The simulation model is a control parameter adapting apparatus having a condition in which a specific problem is most likely to occur by taking into account all variations in dynamic characteristics of the control system among products. In the control parameter adaptation device according to claim 1 or 2,
The control parameter adapting apparatus, wherein the dynamic characteristics of the control system include viscous friction and Coulomb friction of the mechanical components. In the control parameter adaptation device according to any one of claims 1 to 3,
A control parameter adaptation apparatus comprising notification means for notifying a verification result by the verification means. In the control parameter adaptation device according to claim 4,
The notification by the notification means is a control parameter adaptation device including guidance related to adaptation of control parameters. In the control parameter adaptation device according to any one of claims 1 to 5,
The control system is a control parameter adaptation device that is an electric power steering system.

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