JP2008269080A - Design support device for controller for electric power steering device and controller for electric power steering device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a design support device for a controller for an electric power steering device capable of efficiently reflecting required specifications to more detailed design items, reducing a development period and trial production cost, rapidly performing optimum designing, and sharing information about design among a designer team. <P>SOLUTION: In the design support device for the controller for an electric power steering device, an external storage device 105 stores a plurality of control modules constructed by dividing a control program mounted in the controller of the electric power steering device according to control functions, a setting parameter group about a plurality of control modules, and a table qualitatively showing presence/absence of relation between classification of required specification to the controller and classification of control function items. The classification of the control function items in the table, the control modules, and the setting parameter group are associated mutually. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a design support device that supports the design of a control device for an electric power steering device.

An electric power steering device (EPS) used in a conventional vehicle senses a steering torque input by a steering wheel with a torque sensor, and obtains an auxiliary torque corresponding to the steering torque by a motor. The steering assist torque is applied to the steering device, and the steering force of the steering device input by the steering person is reduced.
In the electric power steering device, the steering torque is applied to the steering device by transmitting the output torque of the motor to the steering handle or the rack shaft via a transmission mechanism such as a speed reducer. .

  In recent years, such electric power steering devices have been increasingly applied from light vehicles and small vehicles to medium-sized vehicles. For this reason, there is a strong demand for an electric power steering device to cope with high output and high efficiency of the motor that assists the steering of the steering wheel, to deal with various steering performances, and to improve fuel efficiency.

  Along with this, in the development of electric power steering devices, in order to satisfy comprehensive customer demands such as further improvement of safety and steering performance and social demands for reduction of environmental impact, more and more efficient design is increasingly important. Has been. In addition, it is necessary to respond to shortening of the development cycle according to the model change of the electric power steering device, reduction of prototype cost, improvement of development quality, etc., so further advancement of the design process is inevitable. Yes. In particular, such a requirement is very remarkable in the design of the control program for the control device of the electric power steering apparatus, in combination with the maintenance of the software development environment.

  Here, a general design process related to the electric power steering apparatus will be described. The design process is characterized by requirements definition, development environment and development process. The outline will be described below.

  In the requirement definition, after conducting market research, customer requirements corresponding to the vehicle are extracted, items required for the electric power steering device, for example, selection of the motor corresponding to the vehicle, and appropriate control corresponding to the selected motor In order to guide performance and the like, the customer requirements are defined and formulated in the form of requirement specifications. In the development environment, the software part was initially implemented using a machine language such as an assembler. However, due to its high versatility and development tools, it has shifted to C language, which is a high-level language. In the development process of the electric power steering apparatus, the development process is expressed as a so-called V-type process. The V-type process is a process (design process) in which the required specifications required for the electric power steering device for vehicles are refined from the upstream process to the downstream process and developed into design specification items (design process), and from the downstream process to the upstream process For this purpose, a process (verification process) for verifying whether the designed product has a function as required is provided. By showing both of these processes in the V shape, the relationship between the design process and the verification process can be clarified. By the time of mass production, multiple trial production including parameter adjustment of the control system is performed by this process. Will be implemented.

  Among these requirement definitions, the development environment, and the development process, the requirement definition is positioned as an upstream process, and the subsequent development process is performed based on this requirement specification. For this reason, together with the degree of completion of the required specifications, the degree of reflection of the required specifications in the subsequent downstream process will determine the quality of the development of the electric power steering apparatus.

  In order to improve the efficiency of reflecting the required specifications, the QFD (Quality Function Deployment) method is well known as being applied not only to the development of electric power steering devices but also to many other products. (For example, Patent Document 1 and Patent Document 2). QFD method is a two-dimensional table that defines customer product quality (for example, required specifications) into technical characteristics (for example, design specification items) that are related functions and determines the product design quality. Furthermore, it is a method of comprehensive quality control that systematically develops to process elements such as reliability of individual parts. In this case, this two-dimensional table is used as a tool for organizing the relationship between the two elements (vertical axis, horizontal axis). Will be set.

  On the other hand, in order to improve the efficiency of the design of the electric power steering device, adjustment of setting parameters (feedback gain, etc.) in the control system can be adjusted even by inexperienced workers by managing the data and history of the setting adjustment setting group. An apparatus capable of performing the above has been proposed (for example, Patent Document 3).

JP 2000-172729 A Japanese Patent Laid-Open No. 11-288427 JP 2006-15913 A

  However, as in Patent Document 1 and Patent Document 2, for example, even if the association between the required specification and the related function item is clear in the table of the QFD method, as the design progresses from upstream to downstream, the QFD method It is difficult to reflect the found functions in actual design items (for example, selection of parts and program structure), and eventually it is performed manually at the designer's intellectual judgment level. Became intermittent and inefficient.

  Further, in Patent Document 3, only setting parameter setting information is managed, and the designer cannot grasp the relevance information of the control function or the background information for realizing the predetermined control function. In the case of progress, design information is not efficiently shared, and even if the design progresses with incorrect design information, each designer may overlook the error.

  The present invention has been made in view of the above-described circumstances, and the object of the present invention is to efficiently reflect the required specifications in more detailed design items, shortening the development cycle, reducing the cost of trial production, and promptly optimizing the design. The present invention provides a design support device for a control device for an electric power steering device that can share information related to design within a designer team, and a control device for an electric power steering device designed by the design support device. is there.

The above object of the present invention can be achieved by the following constitution.
(1) In a design support device for a control device of an electric power steering device that senses at least a steering torque input by a steering wheel and applies a steering assist force to a steering mechanism by controlling an output torque of a motor.
A plurality of control modules in which a control program installed in the control device is divided according to control functions; a set parameter group related to the plurality of control modules; a classification of required specifications and a classification of control function items for the control device; And a table that qualitatively indicates whether or not
A design support device for a control device of an electric power steering device, wherein the control function item classification of the table is associated with the control module and the set parameter group.
(2) The control module
A torque control system for calculating characteristics of the output torque of the motor; a current control system for performing control related to the driving of the motor; a compensation control system for compensating the output torque of the motor; and a fail-safe for detecting an abnormality. The design support device for the control device of the electric power steering device according to (1), which includes a control system and a sensor control system that controls the output characteristics of sensing.
(3) The set parameter group includes:
Parameters for filter constants included in these control systems and for filtering the internal signals, and parameters for fail-safe thresholds included in the fail-safe control system and threshold values for determining an abnormality A gain parameter that is included in the control system and defines amplification of an internal signal; and table data that is included in the torque control system and indicates a correlation between the sensed steering torque and the output torque of the motor. The design support device for the control device for the electric power steering device according to (2), configured as a plurality of combination groups.
(4) A control device for an electric power steering device, in which a control program designed by the design support device for the control device for the electric power steering device according to any one of (1) to (3) is mounted.

  According to the above configurations (1) to (3), the control program installed in the vehicle is divided and recorded as a control module for each control function, and the required specification classification and control function item classification The control function items are individually associated with the control modules in a table qualitatively indicating whether or not there is a relationship. In addition, setting parameter groups related to the plurality of control modules are also recorded and held in association with setting mechanism items in the table. For this reason, when the design progresses from the upstream process to the downstream process, the required specifications can be efficiently reflected, and the development cycle can be shortened, the prototype cost can be reduced, and the optimum design can be performed quickly. Furthermore, since the design progresses continuously from the table and the control program is implemented, information regarding the design can be shared within the designer team.

  Furthermore, according to the configuration of (4), since the design can be advanced efficiently in the development of the electric power steering apparatus, the product quality of the developed electric power steering apparatus itself can be improved and the manufacturing cost can be suppressed. I can expect.

  According to the present invention, the required specifications can be efficiently reflected in more detailed design items, the development cycle can be shortened, the prototype cost can be reduced, and the optimum design can be quickly performed, and information on the design can be shared within the designer team. be able to.

  Embodiments according to the present invention will be described below with reference to the drawings.

  First, a typical configuration of the electric power steering apparatus will be described with reference to FIG. FIG. 1 is a schematic diagram showing the entire configuration of the electric power steering apparatus. The configuration of the present embodiment is not limited at all by this, and various configurations can be applied as appropriate.

  In the electric power steering apparatus according to the present embodiment, the column shaft 2 of the steering handle 1 is coupled to the tie rod 6 of the steering wheel via the reduction gear 3, the universal joints 4a and 4b, and the pinion rack mechanism 5. The column shaft 2 is provided with a torque sensor 10 that detects (senses) the steering torque of the steering handle 1, and a motor 20 that assists the steering force of the steering handle 1 is connected via the reduction gear 3 to the column shaft 2. Is bound to. Further, a vehicle speed sensor 12 for detecting the speed of the vehicle is attached to the steering wheel. Furthermore, a motor angle detection circuit 21 configured by, for example, a resolver is attached to the motor 20 to detect the rotation angle of the motor.

  Then, power is supplied from the battery 14 via the ignition key 11 and the relay 13 to a control unit (control device) 30 that controls the electric power steering device. As a result, the control unit 30 determines the steering assist command value of the assist command based on the steering torque signal T, the vehicle speed signal V, and the motor angle signal θ detected by the torque sensor 10, the vehicle speed sensor 12, and the motor angle detection circuit 21, respectively. By calculating I and controlling the current (assist current) supplied to the motor 20 based on the calculated steering assist command value I, steering assist force is applied to the steering handle 1 to realize assist control. is doing.

  The control unit 30 is mainly composed of an MPU. Inside the MPU, a control program stored in a ROM or the like is read and the assist control is performed. In order to perform the assist control accurately, the control unit 30 adjusts the motor applied voltage so that the deviation between the current control value of the current to be applied to the motor 20 and the detected motor current is zero. In general, the motor voltage is adjusted by adjusting the duty ratio of PWM (pulse width modulation) control (see FIG. 2).

  FIG. 2 is a block diagram showing a control function of a control program executed by the MPU constituting the control unit 30. As shown in FIG. Further, the control program can be divided (modulated) for each control function, and this modularized (control function module) is stored in the design support device of the control unit 30 described later. Used in design. The same components as those in FIG. 1 are denoted by the same reference numerals, and description thereof is simplified or omitted.

As shown in FIG. 2, the control unit 30 includes a torque control system that calculates characteristics of the output torque of the motor 20 using the steering torque signal T, a current control system that performs control related to driving of the motor 20, and a motor It is composed of a compensation control system for correcting 20 output torque (steering assist command value). The torque control system includes a steering assist command value calculation unit 301, a differential controller 302, and the like. The current control system includes a subtractor 316, a current controller 309, a PWM controller 310, a motor drive circuit 311, and a motor current detector 317. The compensation control system includes a phase compensator 303, a convergence controller 306, an inertia compensator 307, and a SAT estimation compensator 308.
It should be noted that a current value applied to the motor 20 (detected value of the motor current detector 317, etc.) or a signal such as the operation torque signal T is detected to make an abnormality diagnosis, and the diagnosis result is assisted controlled. A fail-safe control system is also implemented (not shown). In addition, the analog signal output from the torque sensor 10 and the vehicle speed sensor 12 has an analog amplifier function and an anti-aliasing filter function so that the control unit 30 can perform arithmetic processing, and the analog signal is converted into a digital signal. A sensor control system for conversion and control is also mounted (not shown).

  The steering torque signal T is detected by the torque sensor 10 and input to the steering assist command value calculation unit 301, the differentiation controller 302, and the SAT estimation compensator 308.

  The steering assist command value calculation unit 301 outputs a steering assist command value I to be supplied to the motor 20 based on the steering torque signal T and the vehicle speed signal V, and inputs the steering assist command value I to the phase compensator 303. . The steering torque is greatest when the vehicle is stopped. On the other hand, as the vehicle speed increases, the steering torque decreases. Therefore, the steering assist command value calculation unit 301 supplies the steering torque signal T to the motor 20. By changing the relationship with the steering assist command value I according to the vehicle speed signal V, the steering feeling is improved and the vehicle behavior is stabilized.

Phase compensator 303 performs a phase compensation steering assist command value I, and outputs a steering assist command value I _P which phase compensation is applied to the subtractor 313 and the estimated SAT compensator 308. The phase compensator 303 takes in the vehicle speed signal V, removes the peak value at the resonance frequency of the resonance system composed of the inertia element and the spring element included in the output torque of the motor 20, and responds and stabilizes the control system. To compensate for the phase shift of the resonance frequency that hinders the above, to improve the transient characteristics or stabilize the control system.

  The differential controller 302 takes in the steering torque signal T, corrects the steering assist command value I according to the fluctuation of the steering torque signal T, suppresses the fluctuation of the output torque by the motor 20, and near the steering neutral point. Improves control responsiveness and realizes smooth and smooth steering. The output result of the differentiation controller 302 is output to the subtracter 313.

  On the other hand, the motor angular velocity estimation unit 305 estimates the motor angular velocity ω based on the output signal θ of the motor angle detection circuit 21. The motor angular velocity ω is input to the convergence controller 306, the motor angular acceleration estimation unit 305, and the SAT estimation compensator 308, respectively. Further, the motor angular acceleration estimation unit 305 performs, for example, differentiation processing on the motor angular velocity ω to estimate the motor angular acceleration α, and outputs it to the inertia compensator 307 and the SAT estimation compensator 308.

  A convergence controller 306 receives the vehicle speed signal V and the motor angular velocity ω as inputs, and corrects the steering assist command value I in a direction that prevents the steering handle 1 from rotating in order to improve the convergence of the vehicle. A brake is applied to the swinging motion of the steering handle 1, and the behavior of the steering handle 1 after steering is stabilized.

  Then, the inertia compensator 307 receives the motor angular acceleration α and the vehicle speed signal V as input, and responds to a change in the inertia system related to the drive system such as the steering handle 1, the pinion rack mechanism 5, the motor 20, and the reduction gear 3. The steering assist command value I is corrected to suppress fluctuations in the assist torque. Thus, the inertia of the drive system is prevented from being transmitted to the steering person, and the steering feeling is improved.

The SAT estimation compensator 308 receives the steering torque signal T, the steering assist command value _IP , the motor angular acceleration α, and the motor angular velocity ω, and sets the steering assist command value I in a direction that assists the operation of the steering handle 1. It corrects and improves the return of the steering handle 1 after steering.

  Adder 315 adds the output of inertia compensator 307 and the output of SAT estimation compensator 308 and outputs the result to adder 314. The adder 314 adds the output of the adder 315 and the output of the convergence controller 306 and outputs the result to the subtracter 313.

Subtractor 313, and an output steering assist command value I _P of derivative controller 302 and addition operation, and the output of the adder 314 from the result of the addition operation to subtraction processing, the result as the torque command value It outputs to the current command value calculation part 312 comprised with a 2-3 phase converter etc.

  Next, the subtractor 316 subtracts the output of the motor current detector 317 from the current command value calculated by the current command value calculation unit 312 and outputs the result to the current controller 309. The current controller 309 takes in the output signal of the subtractor 316 and calculates a voltage command value based on the output signal. Further, the PWM controller 310 calculates the duty ratio from the voltage command value, and the motor drive circuit 311 drives the inverter circuit to apply a voltage to the motor 20.

  In the present embodiment, the control unit calculates the steering command value based on the input of the steering torque signal T and the vehicle speed signal V. However, the present invention is not limited to this, and at least the steering torque signal is input. Thus, the steering command value I can be calculated.

  Here, with reference to FIG. 3, the design support apparatus 100 for designing the control program which implement | achieves such a control function is demonstrated.

As shown in FIG. 3, the design support apparatus 100 includes a CPU 101, a main memory 102 such as a RAM, a display 103 such as a display, an operation input device 104 such as a keyboard and a mouse, and an external storage device 105 such as a hard disk. And an interface 106 for transmitting / receiving data to / from a control unit incorporated in the vehicle, a bus 107 for exchanging data between elements such as the CPU 101 and the main memory 102, and the like. Can be built on top. In addition, in the external recording device 105 of the design support device 100, a plurality of control modules of a control program installed in the control unit 30, a set parameter group related to the plurality of control modules, and a QFD method are used. A table (two-dimensional table) qualitatively indicating whether or not there is a relationship between a plurality of required specification classifications and a plurality of control function items of the electric power steering control device is recorded and held.
Each control module has a configuration in which a control program is divided into control functions. For example, when the control unit 30 is mounted, it is configured so that it can be automatically converted into a mounting code collectively via the interface 106.

  The set parameter group includes the torque control system, the sensor control system, and the like, more specifically, the differential controller 302, the phase compensator 303, the torque sensor 10, and a sensor control system filter for the vehicle speed sensor. Filter constant parameters for filtering signals included in the system (internal signals) to be processed, and fail that is included in the fail-safe control system and is a threshold value for determining abnormality A parameter for safety threshold, a gain parameter that is included in the control system such as the torque control system and the current control system, and defines amplification of an internal signal, and a steering torque that is included in the torque control system and sensed Multiple combinations including parameters such as table data (assist map) indicating the correlation between the motor and the output torque of the motor It is configured as.

  The design support apparatus 100 is configured to be connectable with design support software such as Matlab / Simulink (trade name) and JMAG (trade name), or includes such design support software. It may be configured as follows. In this case, design items corresponding to the required specifications can be predicted and evaluated as they are, and the design efficiency can be further improved.

  The table qualitatively sets a required specification classification A and an electric power steering control function item (equivalent to specifications) B as the element classification. In the table, the classification A And the classification B are expressed so that the importance can be considered. For this reason, the designer uses the design support apparatus 100 to call this table from the external storage device 105, and in accordance with the restriction condition (for example, selection of the control function item corresponding to each required specification according to the table). Manufacturing cost, environmental performance, etc.).

  Further, the control program implemented in the electric power steering apparatus has a structure having a plurality of control modules divided for each function before the implementation, and the control function items shown in the table, Control modules are associated with each other. In addition, as described above, it relates to the parameters in the control module, such as the viscoelasticity and inertia characteristics of the transfer function, the time constant, the gain parameter, etc., and is applied to each individual control module or the entire system. Set parameter groups are individually associated with the control function items. Thereby, parameters can be adjusted according to a predetermined standard (table) with respect to the control module extracted from the table, and complexity of parameter adjustment can be suppressed. That is, by the association in the design support apparatus 100, the designer can efficiently reflect the upstream design in the downstream design, and can be easily mounted on the control unit. In particular, by associating the set parameter group, a control function (for example, steering assist command value calculation unit 301, SAT estimation compensator 308, etc.) that requires parameter adjustment from the required specifications is specified, and parameter adjustment of the specified control function is performed. Can be implemented efficiently.

  Next, the design using the design support apparatus 100 configured as described above will be further described. In this embodiment, as an example, the control function of the steering resilience, that is, the association between the control program that realizes the steering assist command value calculation unit 301 and the SAT estimation compensator 308 in the control program will be described. However, the present invention is not limited to this, and can be applied to other control functions as appropriate.

FIG. 4 is a diagram illustrating an example of a design flow when the design support apparatus 100 of the present embodiment is used.
As shown in FIG. 4, when a required specification for steering resilience that is a part of the steering performance of the steering handle 1 is generated from a customer's request, the designer uses the design support device 100 to perform the external storage device 105. Then, the table is called, and control function items satisfying the required specifications are extracted. The control function items thus extracted, that is, the control modules of the SAT estimation compensator (SAT loss torque compensation unit in the figure) 308 and the steering assist command value calculation unit 301 in this embodiment are automatically associated with each other. At the same time, a set parameter group related to these control modules is also selected. Based on the control module and setting parameters selected in this way, the control block is constructed in design support software such as Matlab / Simulink (trade name), JMAG (trade name), etc. The setting parameters are input to the control program, and under the conditions of the control block and the setting parameters, the influence point and the change point of the entire system are derived and verified.

Further, a specific flow of design / verification when this design support apparatus 100 is used will be described with reference to FIG.
First, in the upstream design (system design / verification process), the performance items, process days, and manufacturing costs of the entire system to be realized are estimated from the required specifications. In other words, the designer uses the design support device to develop information reflecting the required specifications on the performance items of the entire system that the designer should consider, and derives the performance corresponding to the required specifications. Then, from the derived performance, the number of design process days and the manufacturing cost of the electric power steering apparatus are estimated.

  In the next process, that is, the module design / verification process, information about each element listed in the performance item is developed from the derived performance item to the technical function item using the design support device, and the element is supported. In the design of the technical function to be performed, that is, the control program, the control function is extracted as an item.

  Then, in the subsequent process, that is, the component design / verification process, a control module that realizes this control function is selected (part characteristics of the motor, pinion rack mechanism, etc. unless the control program is designed), and the selected control is performed. Prediction / evaluation is performed with support software based on the module, and detailed man-hours and manufacturing costs are calculated. In addition, the design support apparatus 100 may separately manage problems and progress that have occurred in each process, centrally manage requirements and issues agreed upon by designers, and share information. Good.

  As described above, in the control support device 100 of the present embodiment, the control program installed in the vehicle is divided and recorded as a control module for each control function, and the required specification classification and control function item The control function items are individually associated with the control modules in a table qualitatively indicating whether or not there is a relationship with the classification. In addition, the set parameter groups related to the plurality of control modules are also recorded and held in association with the control function items in the table. For this reason, when the design progresses from the upstream process to the downstream process, the required specifications can be efficiently reflected, and the development cycle can be shortened, the prototype cost can be reduced, and the optimum design can be performed quickly.

  Furthermore, since the design progresses using the table continuously from the initial stage of the design and the control program is implemented, it is possible to share information on the design within the designer team, and an error occurs. Even so, the error can be confirmed between the teams and can be corrected in advance.

  In addition, since the design is performed using the design support device 100 as described above, a control device for the electric power steering device can be developed efficiently, and the quality of the electric power steering device itself can be improved and the manufacturing cost can be suppressed. Become.

  This is the end of the description of specific embodiments. However, aspects of the present invention are not limited to these embodiments, and modifications, improvements, and the like can be made as appropriate.

It is the schematic which shows the whole structure of an electric power steering apparatus. It is a block block diagram which shows the control function of the control program performed with a control apparatus. 1 is a system configuration diagram of a design support apparatus according to the present invention. It is the figure which showed an example of the flow of the design at the time of using the design assistance apparatus which concerns on this invention. It is the figure which showed the specific flow of the design and verification at the time of using the design support apparatus which concerns on this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Steering handle 2 Column shaft 3 Reduction gear 4a, 4b Universal joint 5 Pinion rack mechanism 6 Tie rod 10 Torque sensor 20 Motor 30 Control unit (control device)
DESCRIPTION OF SYMBOLS 100 Design support apparatus 105 External memory | storage device 301 Steering assistance command value calculating part 302 Differential controller 303 Phase compensator 308 SAT estimation compensator

Claims (4)

In a design support device for a control device of an electric power steering device that senses at least a steering torque input by a steering wheel and controls a motor output torque to apply a steering assist force to a steering mechanism.
A plurality of control modules in which a control program installed in the control device is divided according to control functions; a set parameter group related to the plurality of control modules; a classification of required specifications and a classification of control function items for the control device; And a table that qualitatively indicates whether or not
A design support device for a control device of an electric power steering device, wherein the control function item classification of the table is associated with the control module and the set parameter group. The control module is
A torque control system for calculating characteristics of the output torque of the motor; a current control system for performing control related to the driving of the motor; a compensation control system for compensating the output torque of the motor; and a fail-safe for detecting an abnormality. The design support apparatus of the control apparatus of the electric power steering apparatus according to claim 1, comprising a control system and a sensor control system that controls an output characteristic of sensing. The set parameter group includes:
Parameters for filter constants included in these control systems and for filtering the internal signals, and parameters for fail-safe thresholds included in the fail-safe control system and threshold values for determining an abnormality A gain parameter that is included in the control system and defines amplification of an internal signal; and table data that is included in the torque control system and indicates a correlation between the sensed steering torque and the output torque of the motor. The design support device for the control device of the electric power steering device according to claim 2, which is configured as a plurality of combination groups.   The control apparatus of the electric power steering apparatus by which the control program designed by the design assistance apparatus of the control apparatus of the control apparatus of the electric power steering apparatus as described in any one of Claims 1-3 was mounted.

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