JP2011161987A - Electric power steering device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To reduce the processing load while diagnosing the defect of a storage device provided in a device that controls an electric power steering device. <P>SOLUTION: A CPU 101, a ROM 102 and a RAM 103 are used for controlling the electric power steering device. The ROM 102 and the RAM 103 store information used for controlling the electric power steering device, and are divided into a plurality of areas. Each of the plurality of areas corresponds to each of prescribed processing units in the control of the electric power steering device. The CPU 101 selects a diagnosis object area out of the plurality of areas based on the processing load of the control, and diagnoses the selected area. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to an electric power steering apparatus, and more particularly to diagnosis of a storage device mounted on a computer that performs steering control.

  In order to reduce the steering force of vehicles such as passenger cars and trucks, there is a so-called electric power steering (EPS) device that assists steering by an electric motor. The electric power steering apparatus applies power generated by the electric motor to a steering shaft or a rack shaft via a reduction gear. Since the electric power steering device plays a role of steering the vehicle, particularly high safety and reliability are required among the devices constituting the vehicle. For this reason, the primary storage devices such as ROM and RAM of the computer that controls the electric power steering device are also diagnosed at any time and stored in the primary storage device itself or the primary storage device so that the failure can be detected quickly. It is diagnosed whether there is a problem with the information.

  For example, Patent Document 1 discloses a diagnostic technique for ROM included in a control computer used in an electric power steering apparatus. In this technique, the ROM area is composed of a plurality of cells made up of a predetermined number of bits, and data of some of the plurality of cells is added for each diagnosis period, and obtained in the previous diagnosis period. When the data addition values of all cells in the ROM area are obtained by adding the data of some other cells to the addition value of some cell data during the current diagnostic period, the sum of the addition values is obtained. And the specified value.

JP 2004-133635 A

  However, in the technique disclosed in Patent Document 1, when the addition of data is obtained for all areas of the ROM, the sum of the addition values is compared with the specified value, so that the addition of data for all areas of the ROM is performed. The processing load for obtaining data is high, which may affect the control operation.

  The present invention has been made in view of the above, and an object of the present invention is to reduce a processing load when diagnosing a malfunction of a storage device included in a device that controls an electric power steering device.

  In order to solve the above-described problems and achieve the object, the present invention includes an electric motor that applies an auxiliary steering force to a steering mechanism of a vehicle, and steering calculated using at least a steering torque and a vehicle speed with respect to the steering mechanism. In the electric power steering apparatus that drives and controls the electric motor based on the auxiliary command value, information used for controlling the electric power steering apparatus is stored and divided into predetermined processing units in the control of the electric power steering apparatus. A storage device having a plurality of areas, a processing device that controls the electric power steering device, selects an area to be diagnosed from a plurality of areas based on a processing load of control, and diagnoses the selected area; Is an electric power steering device characterized by comprising:

  The present invention divides the storage area of the storage device into a plurality of areas for each predetermined processing unit in the control of the electric power steering device, selects an area to be diagnosed from the plurality of areas based on the processing load of the control, Diagnose the selected area.

  In this way, the diagnosis target area is selected from a plurality of areas based on the processing load of the control, and it is determined whether or not a failure has occurred only in the selected area. As a result, it is possible to reduce the processing load when diagnosing a malfunction of the storage device included in the device that controls the electric power steering device, and to improve the real-time performance of the diagnosis and / or control.

  The information used for controlling the electric power steering apparatus is, for example, a computer program or data used for controlling the electric power steering apparatus. Further, the minimum unit of processing is to process and output some input information in the control of the electric power steering apparatus.

  As a desirable mode of the present invention, in the electric power steering device, it is preferable that the processing device selects all areas and diagnoses the selected areas when the control processing load is smaller than a predetermined threshold. . As a result, when the control processing load is smaller than the threshold value, all areas are diagnosed, so that the safety of the electric power steering apparatus is further improved.

  As a desirable mode of the present invention, it is preferable to select a larger number of areas as the control processing load is smaller, select a smaller area as the control processing load is larger, and diagnose the selected area. Accordingly, the safety of the electric power steering device and the reduction of the processing load can be realized in a well-balanced manner based on the control processing load.

  As a desirable aspect of the present invention, in the electric power steering apparatus, when the processing device determines that a failure has occurred in the area, the processing device executes a backup process corresponding to the processing unit of the area in which the failure has occurred. It is preferable. As a result, even if there is a problem, the operation of the electric power steering apparatus can be continued, so that the safety of the electric power steering apparatus is further improved.

  As a desirable aspect of the present invention, in the electric power steering apparatus, the backup process is preferably a process of controlling the electric power steering apparatus with a fixed value. Thus, since it controls by a fixed value as backup processing, operation | movement of an electric power steering apparatus can be continued by simple processing.

  As a desirable mode of the present invention, in the electric power steering device, it is preferable that the processing device stops applying the auxiliary steering force when it is determined that there is a problem in the backup processing. Thus, when a problem occurs in the area corresponding to the backup processing, safety can be ensured by not using such information.

  The present invention can reduce a processing load when diagnosing a malfunction of a storage device included in a device that controls an electric power steering device.

FIG. 1 is a diagram illustrating a configuration of an electric power steering apparatus according to the present embodiment. FIG. 2 is a schematic diagram illustrating a hardware configuration of a control unit that controls the electric power steering apparatus according to the present embodiment. FIG. 3 is a functional block diagram showing a functional configuration of a control unit that controls the electric power steering apparatus according to the present embodiment. FIG. 4 is a functional configuration diagram for executing a diagnosis process of the storage device provided in the control unit that controls the electric power steering apparatus according to the present embodiment. FIG. 5 is a flowchart showing a control procedure of the electric power steering apparatus. FIG. 6 is a flowchart illustrating an example of a processing procedure of ROM and RAM diagnosis according to the present embodiment. FIG. 7 is a diagram illustrating an example of a diagnosis map for each load representing an area selected as a diagnosis target based on the processing load of control. FIG. 8 is a flowchart illustrating an example of a processing procedure of ROM diagnosis according to the present embodiment. FIG. 9 is a diagram showing an outline of the contents of the ROM storage area according to the present embodiment. FIG. 10 is a flowchart illustrating an example of a processing procedure for RAM diagnosis according to the present embodiment.

  Hereinafter, the present invention will be described in detail with reference to the drawings. The present invention is not limited by the mode for carrying out the invention (hereinafter referred to as an embodiment). In addition, constituent elements in the following description include those that can be easily assumed by those skilled in the art, those that are substantially the same, and those in a so-called equivalent range.

  FIG. 1 is a diagram illustrating a configuration of an electric power steering apparatus according to the present embodiment. The electric power steering apparatus according to the present embodiment stores information used for controlling the electric power steering apparatus and has a plurality of areas divided for each predetermined processing unit in the control of the electric power steering apparatus. And a processing device that controls the electric power steering device and determines whether or not a failure has occurred in the storage device. Then, in the control of the electric power steering device, the processing device selects an area to be diagnosed from a plurality of areas based on the control processing load, and diagnoses the selected area.

  The electric power steering apparatus 100 is mounted on a vehicle and assists the operation of the handle wheel 1 by the driver of the vehicle. A column shaft 2 of the handle wheel 1 is connected to a tie rod 6 of a steered wheel via a reduction gear 3, universal joints 4a and 4b, and a rack and pinion mechanism 5. The column shaft 2 is provided with a torque sensor 10 that detects the steering torque T of the handle wheel 1. A reduction gear 3 is attached to the column shaft 2. The reduction gear 3 increases the torque generated by the electric motor 20 and transmits it to the column shaft 2. With such a structure, the steering force of the handle wheel 1 is assisted by the torque generated by the electric motor 20.

  In the present embodiment, the electric power steering apparatus 100 is a column assist type apparatus that transmits the torque of the electric motor 20 to the column shaft 2, but the type of the electric power steering apparatus is not limited to this. For example, the electric power steering device 100 may be a pinion assist type or a rack assist type.

  The electric motor 20 is, for example, a brushless motor or a brush motor. An ECU (Electronic Control Unit, hereinafter referred to as a control unit) 30 that controls the electric power steering apparatus 100 is supplied with electric power from the battery 14 via a power supply relay 13 incorporated therein, and an ignition signal is output from the ignition switch 11. Is sent. Further, the control unit 30 calculates a current command value for the electric motor 20 based on the steering torque T detected by the torque sensor 10 and the vehicle speed (vehicle speed) V detected by the vehicle speed sensor 12. The control unit 30 is a device that controls the electric power steering device 100 (a control device for the electric power steering device). Based on the current value (current detection value) supplied to the motor 20 and the current command value, the control unit 30 controls the drive of the motor 20 so that the current detection value of the motor 20 follows the current command value.

  FIG. 2 is a schematic diagram illustrating a hardware configuration of a control unit that controls the electric power steering apparatus according to the present embodiment. As shown in FIG. 2, the control unit 30 includes a power relay 13, a control computer 110, an electric motor drive circuit 15, a current detection circuit 16, a position detection circuit 17, and the like. A control computer 110 of the electric power steering apparatus 100 includes a CPU (Central Processing Unit) 101, a ROM (Read Only Memory) 102, a RAM (Random Access Memory) 103, an EEPROM (Electrically Erasable Programmable ROM) 104, an interface (I / F). ) 105, an A / D (Analog / Digital) converter 106, a PWM (Pulse Width Modulation) controller 107, and the like, which are connected to the bus. The CPU 101 is a processing device, and controls the electric power steering apparatus 100 by executing a computer program for control of the electric power steering apparatus 100 (hereinafter referred to as a control program) stored in the ROM 102.

  The ROM 102 stores a control program, a diagnostic computer program (hereinafter referred to as a diagnostic program) for diagnosing the ROM 102 and the RAM 103, or data used for controlling and diagnosing the electric power steering apparatus 100. The RAM 103 is used as a work memory for operating a control program and a diagnostic program. The EEPROM 104 stores control data input and output by the control program. The control data is used on the computer program for control developed in the RAM 103 after the control unit 30 is turned on, and is overwritten in the EEPROM 104 at a predetermined timing.

  The ROM 102, the RAM 103, the EEPROM 104, and the like are storage devices that store information, and are storage devices (primary storage devices) that can be directly accessed by the CPU 101. Since the ROM 102, the RAM 103, the EEPROM 104, and the like store a control computer program and control data, the CPU 101 executes a diagnosis of the presence or absence of a defect. At this time, the ROM 102, the RAM 103, and the EEPROM 104 may all be diagnosed as storage devices, but in the present embodiment, the ROM 102 that is frequently used during the control of the electric power steering device 100 among the storage devices. Assume that the RAM 103 is diagnosed.

  The diagnosis of the storage device according to the present embodiment can reduce the diagnostic processing load and can improve the real-time property of diagnosis and / or control. For this reason, by using the diagnosis of the storage device in the present embodiment for the ROM 102 and the RAM 103 that are frequently used during the control of the electric power steering apparatus 100, the diagnosis processing load can be reduced, and the diagnosis and / or control can be performed. Real-time performance can be improved. Note that the diagnosis of the storage device in the present embodiment for the storage device (for example, the EEPROM 104) other than the ROM 102 and the RAM 103 is not excluded.

  The A / D converter 106 inputs the steering torque T from the torque sensor 10, the current detection value Im of the electric motor 20 from the current detection circuit 16, the signal of the rotation angle θ of the electric motor 20 from the position detection circuit 17, and the like. Convert to digital signal. The interface 105 is connected to an in-vehicle network such as a CAN (Controller Area Network). The interface 105 is for receiving a vehicle speed V signal (vehicle speed pulse) from the vehicle speed sensor 12.

  The PWM controller 107 outputs a PWM control signal for each phase of UVW based on the current command value for the electric motor 20. The electric motor drive circuit 15 is configured by an inverter circuit or the like, and drives the electric motor 20 based on a signal output from the PWM controller 107. The current detection circuit 16 detects the value (current detection value) Im of the current supplied to the electric motor 20 and outputs it to the A / D converter 106. The position detection circuit 17 outputs an output signal of the position sensor 25 (for example, a resolver or the like) to the A / D converter 106 as the rotation angle θ of the electric motor 20. In the above configuration, the CPU 101 functions as a diagnostic unit and a processing load calculation unit by executing a diagnostic program stored in the ROM 102.

  FIG. 3 is a functional block diagram showing a functional configuration of a control unit that controls the electric power steering apparatus according to the present embodiment. The control of the electric power steering apparatus 100 will be described with reference to FIG. As shown in FIG. 3, the control unit 30 includes a torque control unit 30a, a current control unit 30b, and a torque compensation unit 30c.

  The torque control unit 30a includes an assist amount calculation unit 111, a torque differentiator 112, and a phase compensation unit 113. The assist amount calculation unit 111 calculates the assist torque Tm corresponding to the current steering torque Tr and the vehicle speed V by referring to the assist map. Note that the assist amount calculation unit 111 reduces the assist torque Tm so that the operation of the handle wheel 1 shown in FIG. 1 becomes light when the vehicle speed V is low, and the operation of the handle wheel 1 becomes heavy when the vehicle speed V is high. Can be calculated.

  The torque differentiator 112 calculates the differential value of the steering torque Tr and adds it to the assist torque Tm, whereby the control responsiveness near the neutral point of the handle wheel 1 can be improved. The phase compensation unit 113 compensates for rapid fluctuations in the steering torque Tr, and performs phase compensation for maintaining control stability. In addition, a robust stabilization compensator is provided in the phase compensator 113, and the peak value at the resonance frequency of the resonance system including the inertia element and the spring element included in the torque detection system is removed, thereby inhibiting control response and stability. The resonance frequency phase shift may be compensated.

  The current control unit 30b includes a current command unit 114, a subtracter 131, a current controller 132, a duty calculator 133, an inverter 134, and a current sensor 135. The current command unit 114 calculates a current command value Id corresponding to the torque command value Td. The subtractor 131 calculates a deviation between the current command value Id calculated by the current command unit 114 and the detected current value Im detected by the current sensor 135. The current controller 132 executes at least one of proportional control, differential control, and integral control so that the deviation between the current command value Id and the current detection value Im approaches zero.

  The duty calculator 133 calculates the duty ratio of the gate drive signal of the inverter 134 so that the current Ir controlled to approach the current command value Id is generated. The inverter 134 outputs the current Ir PWM-controlled according to the duty ratio calculated by the duty calculator 133 to the electric motor 20. The current sensor 135 detects a current Ir flowing through the electric motor 20.

  The torque compensation unit 30c includes a motor angular velocity estimation unit 121, a motor angular acceleration estimation unit 122, a yaw rate convergence control unit 123, a motor inertia compensation unit 124, a SAT (SAT: Self Aligning Torque) estimation unit 125, a friction compensation unit 126, and a subtraction. Units 127a and 127b and adders 128a and 128b. The motor angular speed estimation unit 121 estimates the angular speed ω of the motor 20 based on the rotation angle θ of the motor 20. The electric motor angular acceleration estimation unit 122 estimates the angular acceleration α of the electric motor 20 based on the angular velocity ω of the electric motor 20.

  The yaw rate convergence control unit 123 estimates the yaw rate of the vehicle based on the angular velocity ω of the electric motor 20 and brakes the motion of the steering wheel 1 to swing, thereby improving the yaw convergence of the vehicle. The motor inertia compensation unit 124 estimates the inertial force of the electric motor 20 based on the angular acceleration α of the electric motor 20 and compensates the inertial force of the electric motor 20 to improve control responsiveness. The SAT estimation unit 125 estimates the self-aligning torque Ts based on the steering torque Tr, the assist torque Tm, the angular velocity ω and the angular acceleration α of the motor 20, and compensates the assist torque Tm using the self-aligning torque Ts as a reaction force. By doing so, the road surface information is reflected in the steering wheel operation. The friction compensator 126 estimates a torque (friction torque) Tf that serves as a steering resistance of the handle wheel 1 based on the steering torque Tr, and compensates the friction torque Tf, thereby improving control responsiveness.

  The subtractor 127a subtracts the self-aligning torque Ts from the output (friction torque) Tf from the friction compensation unit 126. The subtractor 127b subtracts the output of the subtractor 127a from the output (inertia compensation value) Ti from the motor inertia compensator 124. The adder 128a adds the output from the subtractor 127b to the output (yaw rate compensation value) Ty from the yaw rate convergence control unit 123. The adder 128b adds the output from the torque differentiator 112 and the output from the adder 128a to the assist torque Tm phase-compensated by the phase compensator 113.

  The current command unit 114, the subtractor 131, the current controller 132, and the duty calculator 133 among the torque control unit 30a, current control unit 30b, and torque compensation unit 30c in FIG. 3 are the control computer 110 shown in FIG. It is realized by. Further, the inverter 134 in the current control unit 30b shown in FIG. 3 is realized by the PWM controller 107 and the motor drive circuit 15 shown in FIG. Further, the current sensor 135 in the current control unit 30b shown in FIG. 3 is realized by the current detection circuit 16 in FIG.

  The steering torque Tr detected by the torque sensor 10 shown in FIG. 2 is input to the assist amount calculation unit 111, the torque differentiator 112, and the SAT estimation unit 125, and the vehicle speed V detected by the vehicle speed sensor 12 of FIG. It is input to the quantity calculation unit 111. Further, the rotation angle θ of the electric motor 20 detected by the position sensor 25 is input to the electric motor angular velocity estimation unit 121. Then, the assist amount calculation unit 111 calculates the assist torque Tm based on the steering torque Tr and the vehicle speed V, and outputs it to the phase compensation unit 113. The phase compensation unit 113 performs phase compensation on the assist torque Tm, and then outputs the result to the adder 128b. When the steering torque Tr is input to the torque differentiator 112, the torque differentiator 112 calculates a differential value of the steering torque Tr and outputs it to the adder 128b.

  When the rotation angle θ of the electric motor 20 is input to the electric motor angular velocity estimation unit 121, the electric motor angular velocity estimation unit 121 calculates the angular velocity ω of the electric motor 20, and the electric motor angular acceleration estimation unit 122, the yaw rate convergence control unit 123, and the SAT. It outputs to the estimation part 125. When the angular velocity ω of the electric motor 20 is input to the electric motor angular acceleration estimation unit 122, the electric motor angular acceleration estimation unit 122 calculates the angular acceleration α of the electric motor 20 and sends it to the electric motor inertia compensation unit 124 and the SAT estimation unit 125. Output. When the angular velocity ω of the electric motor 20 is input to the yaw rate convergence control unit 123, the yaw rate convergence control unit 123 estimates the yaw rate of the vehicle and outputs a yaw rate compensation value Ty for converging the yaw of the vehicle to the adder 128a. .

  When the angular acceleration α of the motor 20 is input to the motor inertia compensation unit 124, the motor inertia compensation unit 124 estimates the inertia force of the motor 20 and subtracts an inertia compensation value Ti that compensates the inertia force of the motor 20. To 127b. Further, when the steering torque Tr, the assist torque Tm, the angular velocity ω and the angular acceleration α of the electric motor 20 are input to the SAT estimation unit 125, the SAT estimation unit 125 estimates the self-aligning torque Ts and outputs it to the subtractor 127a. To do.

The self-aligning torque Ts can be obtained by the equation of motion shown in the following equation (1).
J · α + Fr · sin (ω) + Ts = Tm + Tr (1)
In this equation of motion, when the driver steers the handle wheel 1, a steering torque Tr is generated, and the electric motor 20 generates an assist torque Tm according to the steering torque Tr. As a result, the wheels are steered and a self-aligning torque Ts is generated as a reaction force. At that time, a torque which becomes a steering resistance of the handle wheel 1 is generated by the inertia J of the electric motor 20 and the friction (static friction) force Fr existing in the steering mechanism. Considering the balance of these forces, the equation of motion (1) is obtained.

Here, when the Laplace transform is performed by setting the initial value of the equation (1) to 0 and solving for Ts, the self-aligning torque Ts can be obtained as shown in the following equation (2). Note that (s) means a Laplace operator.
Ts (s) = Tm (s) + Tr (s) −J · α (s) −Fr · sin (ω (s)) (2)

  The subtractor 127a subtracts the self-aligning torque Ts from the friction torque Tf, and outputs the result to the subtractor 127b. The subtractor 127b subtracts the output of the subtractor 127a from the inertia compensation value Ti and outputs the subtraction result to the adder 128a. The adder 128a adds the output from the subtractor 127b and the yaw rate compensation value Ty, and outputs the result to the adder 128b. The adder 128b calculates the torque command value Td by adding the assist torque Tm phase-compensated by the phase compensation unit 113, the output from the torque differentiator 112, and the output from the adder 128a, and sends the torque command value Td to the current command unit 114. Output.

  Then, the current command unit 114 calculates a current command value Id corresponding to the torque command value Td and outputs it to the subtracter 131. In addition, the current detection value Im detected by the current sensor 135 is output to the subtracter 131. Then, the subtractor 131 calculates a deviation between the current command value Id and the current detection value Im and outputs the deviation to the current controller 132. Further, the current controller 132 calculates a current control value so that the deviation between the current command value Id and the current detection value Im approaches 0, and outputs the current control value to the duty calculator 133. The duty calculator 133 calculates the duty ratio of the pulse signal based on the current control value output from the current controller 132 and outputs it to the inverter 134. The inverter 134 generates a current Ir subjected to PWM control based on the duty ratio calculated by the duty calculator 133 and outputs the current Ir to the electric motor 20 to cause the electric motor 20 to generate a torque corresponding to the torque command value Td. .

  FIG. 4 is a functional configuration diagram for executing a diagnosis process of the storage device provided in the control unit that controls the electric power steering apparatus according to the present embodiment. The ROM 102 has a storage area (ROM storage area) 1020 for storing information. The ROM storage area 1020 stores a computer program for control of the electric power steering apparatus 100 and a computer program for diagnosis. In this embodiment, the ROM storage area 1020 is divided into a plurality of areas A, B, C, D, E, F, G, H.

  Each area is divided for each predetermined processing unit in the control of the electric power steering apparatus, and a computer program and data for realizing the processing unit are stored in each area. In the present embodiment, each function (control function) necessary for control of the electric power steering apparatus 100 is divided, and a computer program, data, and the like for realizing the function are stored in each area. In the present embodiment, the processing unit may include processing (diagnosis processing) and function (diagnosis function) necessary for diagnosis of the electric power steering apparatus 100 (the same applies hereinafter). For example, area A is a diagnostic function, area B is a torque differentiation function, area C is a vehicle speed table, area D is a phase compensation function, area E is a convergence compensation function, area F is an inertia compensation function, area G is a SAT estimation function, area H corresponds to the friction compensation function. Here, the area is an area composed of a plurality of predetermined numbers of bits in the ROM storage area 1020 and the RAM storage area 1030.

  The RAM 103 has a storage area (RAM storage area) 1030 for storing information. The RAM storage area 1030 is used as a working area when the CPU 101 executes control of the electric power steering apparatus 100 using computer programs and data stored in the ROM 102. In this embodiment, the RAM storage area 1030 is divided into a plurality of areas a, b, c, d, e, f, g, h. In the present embodiment, each area is divided for each control function of the electric power steering apparatus 100. Each area is used as a working area when the CPU 101 reads out and executes a computer program and data for realizing the functions from the ROM 102.

  The CPU 101 implements a control unit 1010 in the CPU 101 by reading and executing a control program stored in the ROM 102. In addition, the CPU 101 implements a diagnostic unit 1011 and a processing load calculation unit 1012 in the CPU 101 by reading and executing a diagnostic program stored in the ROM 102. Here, the control unit 1010 controls the electric power steering apparatus 100, and executes control functions such as a torque differentiation function, a phase compensation function, and a convergence compensation function at a predetermined timing, whereby the electric power steering apparatus 100 is controlled. To realize steering assistance (steering assistance).

  In the control of the electric power steering apparatus 100, the processing load calculation unit 1012 selects a diagnosis target area from a plurality of areas based on the control processing load, and causes the diagnosis unit 1011 to diagnose the selected area.

  Based on an instruction from the processing load calculation unit 1012, the diagnosis unit 1011 selects a plurality of areas based on a control processing load among a plurality of divided areas of the ROM storage area 1020 of the ROM 102 and the RAM storage area 1030 of the RAM 103. Diagnose the area selected for diagnosis. Diagnosis processing executed by the diagnosis unit 1011 includes, for example, a SUM check, a parity check, and a check that combines a SUM check and a parity check for the ROM 102. The diagnostic processing executed by the diagnostic unit 1011 for the RAM 103 includes, for example, a read / write check for writing predetermined data, reading the written data, and determining whether the read data matches the written predetermined data. There is.

  FIG. 5 is a flowchart showing a control procedure of the electric power steering apparatus. In controlling the electric power steering apparatus 100, in step S1, the CPU 101 constituting the control computer 110 of the control unit 30 determines whether or not the ignition (IG) is ON. Whether or not the ignition is ON is determined by the CPU 101 based on the presence or absence of an ignition signal transmitted from the ignition switch 11 shown in FIG.

  If it is determined No in step S1, that is, if the CPU 101 determines that the ignition is OFF, the CPU 101 continues to monitor the ignition. When it is determined Yes in step S1, that is, when the CPU 101 determines that the ignition is ON, the CPU 101 reads the control program stored in the ROM 102 and executes it, thereby executing the control unit 1010 in the CPU 101. By realizing the control function of the electric power steering apparatus 100 at a predetermined timing, the electric power steering apparatus 100 is controlled.

  In the control of the electric power steering apparatus 100, in the present embodiment, diagnosis of the ROM storage area 1020 of the ROM 102 and the RAM storage area 1030 of the RAM 103 is executed before executing each control function. In step S <b> 2, the CPU 101 reads and executes the diagnostic program stored in the ROM 102, thereby realizing the diagnostic unit 1011 and the processing load calculation unit 1012 in the CPU 101 and diagnoses the ROM 102 and the RAM 103. Next, this diagnosis procedure will be described.

  FIG. 6 is a flowchart showing a procedure for diagnosis of the electric power steering apparatus. When diagnosing the electric power steering apparatus 100, in step S11, the processing load calculation unit 1012 realized by the CPU 101 reading and executing the diagnostic program calculates (calculates) the processing load of the control of the CPU 101. As a method for calculating the processing load of the control of the CPU 101, for example, when the CPU 101 has hardware for calculating the processing load, the CPU 101 obtains the processing load of the CPU 101 by referring to the status information of the CPU 101. Can do. Further, when the CPU 101 does not include such hardware, for example, a flag or a counter is provided for each predetermined processing unit in the control of the electric power steering device, and the predetermined processing unit in the control of the electric power steering device is set. The flags and counters are updated each time they are executed, and by referring to these flags and counters, the execution status of each predetermined processing unit in the control of the electric power steering apparatus is acquired, and the processing load of the control of the CPU 101 is reduced. Can be calculated.

  Next, in step S12, the processing load calculation unit 1012 determines the size of the control processing load in three stages of large, medium, and small. That is, the processing load calculation unit 1012 compares the processing load with a predetermined first threshold, and determines that the processing load is small when the processing load is equal to or less than the first threshold. In addition, the processing load calculation unit 1012 determines the size of the processing load when the processing load is greater than the first threshold value and is equal to or less than a predetermined second threshold value (first threshold value <second threshold value). Judged as medium. Further, the processing load calculation unit 1012 determines that the processing load is large when the processing load is larger than the second threshold.

  FIG. 7 is a diagram illustrating a load-specific diagnosis map that represents an area selected as a diagnosis target based on the processing load. If it is determined in step S12 that the processing load is small, the entire area of the ROM 102 and RAM 103 (Diag (diagnosis) communication area, ..., diagnosis area, nonvolatile memory controller area, ..., torque differentiation area) , Vehicle speed table area, phase compensation area, convergence compensation area, inertia compensation area, SAT estimation area, friction compensation area,...) Are selected as diagnosis targets. If it is determined in step S12 that the processing load is medium, the A area (diagnosis area, nonvolatile memory controller area,..., Torque differentiation area, vehicle speed table) which is a partial area of the ROM 102 and RAM 103 Area, phase compensation area, convergence compensation area, inertia compensation area, SAT estimation area, friction compensation area,...) Are selected as diagnosis targets. If it is determined in step S12 that the processing load is large, the B region (torque differentiation area, vehicle speed table area, phase compensation area, convergence compensation area, partial area of the A region of the ROM 102 and RAM 103, Inertia compensation area, SAT estimation area, friction compensation area,... Are selected as diagnosis targets. Thus, in this embodiment, the smaller the processing load, the larger the area (many areas) is the diagnosis target, and the larger the processing load, the narrower area (the smaller area) is the diagnosis target.

  Referring to FIG. 6 again, when it is determined in step S12 that the processing load is small, in step S13, the processing load calculation unit 1012 selects the areas of the entire area of the ROM 102 and the RAM 103 as diagnosis targets, and selects them. The diagnosis unit 1011 is instructed to diagnose the area that has been processed. In this embodiment, a SUM check is performed as a diagnosis of the ROM 102, and a read / write check is performed as a diagnosis of the RAM 103. The diagnosis order of the ROM 102 and the RAM 103 is not limited.

  FIG. 8 is a flowchart illustrating an example of a processing procedure of ROM diagnosis according to the present embodiment. The diagnostic unit 1011 realized by the CPU 101 reading and executing the diagnostic program executes the process of FIG. 8 for each area to be diagnosed. That is, the diagnosis unit 1011 repeats the process in FIG. 8 as many times as the number of areas to be diagnosed.

  FIG. 9 is a diagram showing an outline of the contents of the ROM storage area 1020. As shown in FIG. 9, fixed values (alternate values) for backup processing used in backup processing are stored at the end of each area A, B,... Of ROM storage area 1020. In the present embodiment, the backup process is a process for controlling the electric power steering apparatus 100 with a fixed value. For example, in the torque differentiation function, the output of the torque differentiator 112 shown in FIG. 3 is a fixed value. In addition, the SUM value of each area is stored before the fixed value for backup processing of each area A, B,... In the ROM storage area 1020.

  Referring to FIG. 8 again, the diagnosis unit 1011 realized by the CPU 101 reading and executing the diagnosis program calculates an addition value (area addition value) of all data in the area in step S21.

  Next, in step S22, the diagnosis unit 1011 determines whether the area addition value calculated in step S21 is equal to the SUM value.

  Next, when the diagnosis unit 1011 determines that the area addition value calculated in step S21 is equal to the SUM value (step S22: Yes), in step S23, the function of the diagnosis target area can be executed (diagnosis target A diagnosis result indicating that there is no abnormality in the area ROM is transmitted to the control unit 1010.

  In addition, when the diagnosis unit 1011 determines that the area addition value calculated in step S21 and the SUM value are not equal (step S22: No), the diagnosis result that the function of the area to be diagnosed is executed by the backup process in step S24. Is transmitted to the control unit 1010.

  A fixed value of each control function is stored at the end of each area of the ROM storage area 1020. Receiving the diagnosis result that the control function is executed by the backup process, the control unit 1010 acquires the fixed value of the control function from the end of the area of the control function realized by the backup process of the ROM storage area 1020, and obtains the fixed value. The electric power steering apparatus 100 is controlled by using this. As a result, even when a problem occurs in the ROM storage area 1020 of the ROM 102, the steering assist by the electric power steering apparatus 100 is continued, so that safety is improved. When the control function is realized by the backup process, the process returns to START, and the control unit 1010 executes control of the electric power steering apparatus 100 until the ignition is turned off.

  There may be a case where a problem occurs in the areas of the ROM storage area 1020 and the RAM storage area 1030 corresponding to the backup process (in this embodiment, an area in which a fixed value for realizing the backup process is stored). In this case, in the present embodiment, the control unit 1010 stops the steering assist by the electric power steering device 100, that is, stops the assist of the steering force by the electric power steering device 100. Thus, safety is ensured by not using the information (fixed value) stored in the area where the problem has occurred.

  FIG. 10 is a flowchart illustrating an example of a processing procedure for RAM diagnosis according to the present embodiment. The diagnosis unit 1011 realized by the CPU 101 reading and executing the diagnosis program executes the process of FIG. 10 for each area to be diagnosed. That is, the diagnosis unit 1011 repeats the process in FIG. 10 as many times as the number of areas to be diagnosed.

  First, the diagnosis unit 1011 realized by the CPU 101 reading and executing the diagnosis program sequentially writes 55h (01010101b) over the entire area in step S31.

  Next, in step S32, the diagnosis unit 1011 sequentially reads data from the entire area and determines whether the data of the entire area is 55h.

  Next, when the diagnosis unit 1011 determines that the data in the entire area is 55h (step S32: Yes), in step S33, AAh (10101010b) is sequentially written in the entire area.

  Next, in step S34, the diagnosis unit 1011 sequentially reads data from the entire area and determines whether the data in the entire area is AAh.

  Next, when the diagnosis unit 1011 determines that the data in the entire area is AAh (step S34: Yes), in step S35, the function of the area to be diagnosed can be executed (in the RAM of the area to be diagnosed). A diagnosis result indicating that there is no abnormality is transmitted to the control unit 1010.

  If the diagnosis unit 1011 determines in step S32 that the data in the entire area is not 55h (step S32: No), or in step S34, the data in the entire area is not AAh (step S34: No). If determined, in step S36, a diagnosis result indicating that the function of the area to be diagnosed is executed by the backup process is transmitted to the control unit 1010.

  Referring to FIG. 6 again, when it is determined in step S12 that the processing load is medium, in step S14, the processing load calculation unit 1012 selects the area A of the ROM 102 and the RAM 103, and selects the selected area. The diagnosis unit 1011 is instructed to make a diagnosis. The diagnosis in step S14 differs from step S13 in that the diagnosis target area is an area A, but the diagnosis processing procedure is the same as in step S13, and thus the description thereof is omitted.

  If it is determined in step S12 that the processing load is large, in step S15, the processing load calculation unit 1012 selects the area of the B area of the ROM 102 and the RAM 103, and diagnoses the selected area. Section 1011 is instructed. The diagnosis in step S15 is different from step S13 in that the diagnosis target area is an area B, but the diagnosis processing procedure is the same as step S13, and thus the description thereof is omitted.

  Thus, the diagnosis of the ROM 102 and the RAM 103 in the area selected based on the control processing load in step S2 shown in FIG. 5 is completed, and the control unit 1010 proceeds to step S3 to execute the control function. Then, returning to START, the control unit 1010 executes control of the electric power steering device 100 until the ignition is turned off.

  In the above description, the diagnosis unit 1011 diagnoses the area selected from the ROM storage area 1020 and the RAM storage area 1030 based on the control processing load. However, the present embodiment is not limited to this. For example, only when the area selected from the ROM storage area 1020 or the RAM storage area 1030 based on the control processing load and the input value for the control function is different between the previous execution time and the current execution time, The diagnosis unit 1011 may diagnose the ROM storage area 1020 and the RAM storage area 1030. In this way, since the diagnosis is not executed when the input value is the same between the previous time and the current time, the time required for the diagnosis can be reduced and the processing load on the CPU 101 can be reduced.

  In the present embodiment, the ROM storage area 1020 and the RAM storage area 1030 are divided for each control function of the electric power steering apparatus 100, and these diagnostic units are set for each control function. Here, the control function is a predetermined role in the control of the electric power steering device 100 by processing and outputting the input (for example, differentiating the torque, compensating the phase, estimating the angular velocity of the electric motor, etc.). Means something that realizes

  The control function is realized by combining processes such as differentiation, integration, and filtering, for example. For this reason, the ROM storage area 1020 and the RAM storage area 1030 may be divided into areas corresponding to the respective processes, with the processes constituting the control function as processing units. Alternatively, the ROM storage area 1020 and the RAM storage area 1030 may be divided into areas corresponding to the respective control blocks using the control block of the electric power steering apparatus 100 as a processing unit. Here, the control block is a collection of a plurality of control functions, such as the torque control unit 30a and the current control unit 30b shown in FIG.

  As described above, in the present embodiment, the storage area of the storage device is divided into a plurality of areas corresponding to the control function of the electric power steering device, and the diagnosis target area is selected from the plurality of areas based on the processing load of control, Diagnose the selected area. As a result, the processing load of the processing apparatus that executes diagnosis can be reduced, and the real-time property of diagnosis and / or control can be improved. In addition, a backup process with a simplified processing procedure compared to each control function is prepared and stored in the storage device. If a problem occurs in the area corresponding to the control function, the area in which the problem has occurred is used. Execute the backup process without As a result, the steering assist by the electric power steering device is continued, so that safety is improved.

  As described above, the electric power steering device according to the present invention is useful for diagnosis of a storage device included in a device that controls the electric power steering device, and is particularly suitable for diagnosis of a storage device that is frequently used.

DESCRIPTION OF SYMBOLS 1 Handle wheel 2 Column shaft 3 Reduction gear 4a, 4b Universal joint 10 Torque sensor 11 Ignition switch 12 Vehicle speed sensor 13 Power supply relay 14 Battery 15 Electric motor drive circuit 16 Current detection circuit 17 Position detection circuit 20 Electric motor 25 Position sensor 30 ECU (control unit) )
30a Torque control unit 30b Current control unit 30c Torque compensation unit 100 Electric power steering device 101 CPU
DESCRIPTION OF SYMBOLS 105 Interface 106 A / D converter 107 PWM controller 110 Control computer 111 Assist amount calculation part 112 Torque differentiator 113 Phase compensation part 114 Current command part 121 Electric motor angular velocity estimation part 122 Electric motor angular acceleration estimation part 123 Yaw rate convergence control part 124 Motor inertia compensation unit 125 SAT estimation unit 126 Friction compensation unit 132 Current controller 133 Duty calculator 134 Inverter 135 Current sensor 1010 Control unit 1011 Diagnosis unit 1012 Processing load calculation unit 1020 ROM storage area 1030 RAM storage area

Claims (6)

In an electric power steering apparatus having an electric motor for applying an auxiliary steering force to a steering mechanism of a vehicle, and driving and controlling the electric motor based on a steering auxiliary command value calculated using at least a steering torque and a vehicle speed for the steering mechanism.
A storage device that stores information used for controlling the electric power steering device and has a plurality of areas divided for each predetermined processing unit in the control of the electric power steering device;
A processing device that controls the electric power steering device, selects an area to be diagnosed from a plurality of areas based on a processing load of control, and diagnoses the selected area;
An electric power steering device comprising:   2. The electric power steering apparatus according to claim 1, wherein when the processing load of control is smaller than a predetermined threshold, the processing device selects all areas and diagnoses the selected areas.   The said processing apparatus selects many areas, so that the processing load of control is small, selects a small area, so that the processing load of control is large, The selected area is diagnosed, The selected area is characterized by the above-mentioned. Electric power steering device.   The electric power according to any one of claims 1 to 3, wherein when the processing device determines that a failure has occurred in the area, the processing device executes a backup process corresponding to a processing unit of the area in which the failure has occurred. Steering device.   The electric power steering apparatus according to claim 4, wherein the backup process is a process of controlling the electric power steering apparatus with a fixed value.   The electric power steering device according to claim 4 or 5, wherein when the processing device determines that the backup processing is defective, the processing device stops applying the auxiliary steering force.

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