JP2013203238A - Steering device - Google Patents

Abstract

When a steering wheel is replaced and its inertial force is changed, deterioration of a driver's operational feeling due to a change in steering characteristics is suppressed.
A steering apparatus includes an inertia force specifying means 102a for specifying an inertial force of a steering wheel 11 and a characteristic correcting means 102b for correcting a steering angular acceleration characteristic of the steering wheel in accordance with the specified inertial force. Prepare. Further, the target steering torque is determined based on the steering angle corresponding to the driver's steering operation. In determining the target steering torque, for example, the characteristics of steering angular acceleration obtained by differentiating the steering angle by two stages are taken into account.
[Selection] Figure 1

Description

  The present invention relates to a technical field of a steering device that determines a target steering torque based on a steering angle corresponding to a driver's steering operation.

  As this type of device, the required steering force (ie, target steering torque) is calculated using the steering angle that changes as the steering wheel is operated and the steering angular velocity and steering angular acceleration calculated from the steering angle. Have been proposed (see, for example, Patent Document 1). In Patent Document 1, the target steering torque is calculated using an equation of motion including an elastic term proportional to the steering angle, a viscosity term proportional to the steering angular velocity, and an inertial term proportional to the steering angular acceleration. Further, the target steering torque including the inertia term cancels the inertial force such as the steering wheel or the electric motor of the electric power steering device, thereby improving the steering feeling of the driver.

  In addition, input the value of the human system dynamic characteristic into the mechanical characteristic of the entire system of the human system dynamic characteristic of the driver and the mechanical system mechanical characteristic of the operation mechanism, and the value of the mechanical system dynamic characteristic in the dynamic characteristic of the entire system is input. A method has been proposed in which an operation reaction force of an operation mechanism is controlled based on a value of the mechanical system dynamic characteristic (see, for example, Patent Document 2). In Patent Document 2, it is assumed that the driving burden is further reduced by obtaining the reaction force of the operation mechanism of the vehicle in accordance with the individual difference for each driver.

JP 2008-149961 A JP 2008-296605 A

  However, in the apparatus described in Patent Document 1 described above, if the steering wheel is replaced and the inertial force of the steering wheel changes, the steering characteristics change. As a result, the target steering torque determined by the steering characteristics before the steering wheel replacement cannot completely cancel the inertial force of the steering wheel, and there is a technical problem that the steering feeling of the driver may deteriorate.

  The present invention has been made in view of the above-described problems, for example, and provides a steering device that can suppress deterioration of a driver's steering feeling caused by a change in steering characteristics when the inertial force of a steering wheel changes. The task is to do.

  In order to solve the above-described problems, a steering device according to the present invention includes an inertial force specifying unit that specifies an inertial force of a steering wheel, and a characteristic of steering angular acceleration of the steering wheel according to the specified inertial force. Characteristic correction means for correcting.

  The steering device according to the present invention determines a target steering torque based on a steering angle corresponding to a driver's steering operation. In determining the target steering torque, for example, the characteristic of the steering angular acceleration obtained by differentiating the steering angle by two stages is taken into account. The steering device according to the present invention may be applied to steering using a steering-by-wire in addition to electric power steering (EPS) using an electric motor.

  “Identify” the inertial force according to the present invention is to detect or output directly or indirectly by using various sensors such as an inertial force sensor, or around a rotation axis that receives the mass point, steering angular acceleration, and this. This is intended to be calculated, estimated or determined using a mathematical formula, function, map or computer program using the distance or the like as a variable or parameter. The “steering angular acceleration characteristic” according to the present invention is, for example, a moment of inertia or a value corresponding to the moment of inertia, and is represented by an equation, a function, or a map. “Correcting” the characteristics of steering angular acceleration means that the characteristic value of steering angular acceleration is the inertial force inherent to the steering wheel (in other words, the inertial force of the steering wheel intended by design or device specifications). It is intended to change the characteristic of the steering angular acceleration so as to take a corresponding value.

  According to the present invention, for example, after the steering wheel is replaced, the inertial force of the steering wheel is specified by the inertial force specifying means. Then, the characteristic correction means corrects the characteristic of the steering angular acceleration of the steering wheel according to the specified inertial force of the steering wheel. Thereby, it is possible to update the characteristics of the steering angular acceleration to those corresponding to the inertial force of the mounted steering wheel. Therefore, when the inertial force of the steering wheel changes, it is possible to suppress changes in steering characteristics that are felt by the driver. Therefore, for example, since the latest steering angular acceleration characteristic is added to the determination of the target steering torque, it is possible to suppress the deterioration of the steering feeling of the driver.

  In the present invention, the characteristic of the steering angular acceleration is corrected according to the change in the inertial force of the steering wheel, but the correction index is not limited to this. For example, any change in the electric motor that constitutes the power steering mechanism and its gear ratio, which may cause the inertial force of the steering wheel to change, may be used as an index for correction.

  One aspect of the steering apparatus according to the present invention further includes information acquisition means for acquiring information relating to the steering wheel, and the inertial force specifying means specifies the inertial force based on the acquired information.

  The “information” according to the present invention indicates various information for specifying the inertial force of the steering wheel in addition to the identification number for each type of steering wheel, the inertial moment of the steering wheel set in advance, and the like.

  According to this aspect, when information related to the steering wheel is acquired by the information acquisition unit, the inertial force inherent in the steering wheel is specified by the inertial force specifying unit based on the acquired information.

  The effect | action and other gain of this invention are clarified from the form for implementing demonstrated below.

1 is a block diagram conceptually showing the structure of a steering device according to an embodiment of the present invention. It is a control block diagram explaining the motor control processing in the steering device of FIG. It is a control block diagram explaining the target steering torque calculation process which concerns on embodiment. It is a flowchart which shows the target steering torque calculation process which concerns on embodiment.

Hereinafter, preferred embodiments of the present invention will be described with reference to the drawings.
<Embodiment>
<Configuration of Embodiment>
First, the configuration of the steering apparatus according to the embodiment will be described with reference to FIG. FIG. 1 is a block diagram conceptually showing the structure of the steering device.

  In FIG. 1, a vehicle 10 including a “steering device” according to the present invention includes a steering wheel 11, a steering shaft 12, a motor 13, a rack and pinion portion 14, a tie rod 15, a knuckle arm 16, and a front wheel 17f. A steering angle sensor 21, an actual steering torque sensor 22, a vehicle speed sensor 23, and an ECU 100.

  A steering wheel 11 (hereinafter simply referred to as “steering 11” as appropriate) is operated by a driver to rotate the vehicle 10. The steering 11 is connected to the rack and pinion unit 14 via the steering shaft 12. The steering shaft 12 is provided with a steering angle sensor 21, an actual steering torque sensor 22, and a motor 13.

  The steering angle sensor 21 detects a steering angle corresponding to the operation of the steering 11 by the driver. The steering angle sensor 21 is configured to supply a detection signal corresponding to the detected steering angle to the ECU 100.

  The actual steering torque sensor 22 detects the torque applied to the steering shaft 12 via the steering 11 as the actual steering torque. The torque sensor 22 is configured to supply a detection signal corresponding to the detected actual steering torque to the ECU 100.

  The vehicle speed sensor 23 is configured to detect the vehicle speed of the vehicle 10 and supply a detection signal corresponding to the detected vehicle speed to the ECU 100.

  The motor 13 is configured to apply torque to the steering shaft 12 under the control of the ECU 100. Hereinafter, the torque that the motor 13 applies to the steering shaft 12 is appropriately referred to as “assist torque”.

  The rack and pinion unit 14 includes a rack gear and a pinion gear, and is configured to operate by receiving rotation from the steering shaft 12. A tie rod 15 and a knuckle arm 16 are connected to the rack and pinion portion 14, and a front wheel 17 f is connected to the knuckle arm 16. In this case, when the tie rod 15 and the knuckle arm 16 are operated by the rack and pinion portion 14, the front wheel 17f connected to the knuckle arm 16 is steered.

  The ECU 100 is an electronic control unit that includes a CPU (Central Processing Unit), a ROM (Read Only Memory), a RAM (Random Access Memory), and the like, and is configured to be able to control the operation of each part of the vehicle 10. ing. The ECU 100 includes a steering information acquisition unit 101, a target steering torque calculation unit 102, an assist torque calculation unit 103, and a motor control unit 104, and is configured to be able to execute an EPS control process and a target steering torque calculation process described later. Yes. In the present embodiment, the ECU 100 is configured to store an identification number of the steering wheel 11 when the steering wheel 11 is mounted on the main body of the vehicle 10.

  As an example of the “information acquisition unit” according to the present invention, the steering information acquisition unit 101 reads the identification number of the steering 11 stored in the ECU 100 and detects the type of the steering 11 corresponding to the read identification number. It is configured. The steering information acquisition unit 101 acquires information (that is, steering type information) for obtaining the inertial force of the steering 11 such as the mass point and the distance around the rotation axis that receives the steering angular acceleration from the type of the steering 11. It is configured as follows.

  The target steering torque calculation unit 103 is typically configured to be able to calculate the target steering torque based on the steering angle detected by the steering angle sensor 21 and the vehicle speed detected by the vehicle speed sensor 23. In the present embodiment, the target steering torque calculation unit 103 includes three calculation units (shown in FIG. 3): a spring unit, a damping unit, and an inertia unit. In the spring portion, a spring term corresponding to the steering angle is calculated, in the attenuation portion, an attenuation term corresponding to the steering angular velocity is calculated, and in the inertia portion, an inertia term corresponding to the steering angular acceleration is calculated. The target steering torque calculation unit 103 is configured to be able to calculate a value obtained by adding the three terms of the spring term, the attenuation term, and the inertia term calculated by the three calculation units as the target steering torque. The spring term is calculated using a function representing an elastic coefficient with the steering angle as an input. The attenuation term is calculated using a function representing a viscous friction coefficient with the steering angular velocity as an input.

  The target steering torque calculation unit 103 includes an inertial force calculation unit 102a and a characteristic correction unit 102b. As an example of the “inertia force specifying means” according to the present invention, the inertial force calculation unit 102a calculates the inertial force of the steering wheel 11 using information obtained by the steering information acquisition unit 101 as an input. It is configured as follows.

  The characteristic correction unit 102b is an example of the “characteristic correction unit” according to the present invention. Based on the inertial force calculated by the inertial force calculation unit 102a, the characteristic correction unit 102b is a function (ie, “steering angular acceleration according to the present invention”). An example of “characteristics of” is corrected. The inertia term is calculated using the corrected function with the steering angular acceleration as an input.

  The assist torque calculation unit 104 is configured to calculate a difference between the target steering torque calculated by the target steering torque calculation unit 103 and the actual steering torque detected by the actual steering torque sensor 22 as the assist torque.

  The motor control unit 105 is configured to be able to control the motor 13 so as to apply the assist torque calculated by the assist torque calculation unit 103.

<Operation of Embodiment>
<EPS control processing>
Next, the motor control process in this embodiment will be described with reference to FIG. FIG. 2 is a control block diagram showing a motor control process for assisting the driver's steering operation.

  In FIG. 2, when the steering angle θ is detected by the steering angle sensor 21 and the vehicle speed V is detected by the vehicle speed sensor 23, the target steering torque Tx is calculated by the target steering torque calculation unit 102. In parallel with this, the actual steering torque Ts as a feedback element is detected by the actual steering torque sensor 22. Subsequently, the target steering torque Tx and the actual steering torque Ts are input to a servo controller (that is, the motor control unit 104) as a control element. Then, the assist torque calculation unit 103 calculates the difference between the target steering torque Tx and the actual steering torque Ts as the assist torque Ta1, and the servo controller applies the assist torque Ta1 to the steering shaft 12 as a control target. The EPS apparatus (that is, the motor 13 or the like) is controlled. At this time, the actual steering torque Ts is detected by the actual steering torque sensor 22 and fed back to the servo controller. By such feedback control, the assist torque Ta1 is updated, so that the driver's steering operation is always assisted.

  In this embodiment, in order to calculate the target steering torque Tx in the target steering torque calculation unit 102, a spring term corresponding to the steering angle, an attenuation term corresponding to the steering angular velocity, and an inertia term corresponding to the steering angular acceleration are respectively provided. Calculated. In the present embodiment, particularly, for example, after the steering 11 is replaced, the characteristic of the steering angular acceleration is corrected prior to the calculation of the inertia term, and the inertia term corresponding to the corrected property is calculated. The calculated inertial term constitutes the target steering torque together with the spring term and the damping term, so that the inertial force of the steering 11 can be completely canceled.

<Target steering torque calculation process>
Next, the target steering torque calculation process in the present embodiment will be described in detail with reference to FIGS. FIG. 3 is a control block diagram showing target steering torque calculation processing by the target steering torque calculation unit 103, and FIG. 4 is a flowchart showing target steering torque calculation processing.

  In FIG. 3, the target steering torque calculation unit 102 includes three calculation units: a spring unit, a damping unit, and an inertia unit. A function representing an elastic coefficient with respect to the steering angle θ is shown in the spring portion. In the attenuation portion, a function representing a viscous friction coefficient with respect to the steering angular velocity ω obtained by differentiating the steering angle θ by one step is shown. In the inertia part, a function representing the inertia moment I with respect to the steering angular acceleration α obtained by differentiating the steering angle θ by two stages is shown. In addition to the steering angular acceleration α, an inertial force F, which is an index for correcting a function representing the moment of inertia I, is input to the inertia part.

  For a function representing the moment of inertia I (shown in the inertia part in FIG. 3), a line segment indicated by a solid line is set by a gain Ki, and is an inertia moment I corresponding to the inertial force F of the steering 11 currently mounted. is there. On the other hand, the line segment indicated by the dotted line is the moment of inertia corresponding to the inertial force of the steering wheel which was set with the gain Ki ′ and was mounted last time.

3 and 4, in the target steering torque calculation process, first, when the steering angle θ detected by the steering angle sensor 21 is input to the spring portion, the spring term T _θ corresponding to the steering angle _θ is calculated. (Step S31). On the other hand, when the steering angular velocity ω is input to the attenuation unit, an attenuation term T _ω corresponding to the steering angular velocity _ω is calculated (step S32). On the other hand, based on the steering type information acquired by the steering information acquisition unit 101, the inertial force F of the steering wheel 11 is calculated by the inertial force calculation unit 102a (step S33). Then, the characteristic correction unit 102b sets a gain Ki corresponding to the calculated inertial force, and the inclination (value) of the inertia moment I is changed with the set gain Ki. That is, the characteristic of the steering angular acceleration α is corrected (step S34). Thereafter, when the steering angular acceleration α is input to the inertia part, the inertial term T _α corresponding to the steering angular acceleration α and the corrected characteristic is calculated (step S35).

When the three terms T _θ , T _ω, and T _α are calculated by the processing of steps S 31, S 32, and S 35 described above, the three terms T _θ , T _ω, and T _α are added together to obtain the target steering torque Tx. Is calculated (step S36). Thereby, a series of target steering torque calculation processes are completed.

  As described above, according to the target steering torque calculation process, the characteristic of the steering angular acceleration α can be updated to one corresponding to the inertial force F of the mounted steering 11. Therefore, when the inertial force F of the steering wheel 11 changes, the latest steering angular acceleration α characteristic is added to the determination of the target steering torque Tx, so that the driver's steering feeling can be prevented from deteriorating. .

  The present invention is not limited to the above-described embodiments, and can be appropriately changed without departing from the gist or concept of the invention that can be read from the claims and the entire specification. A steering apparatus that includes such changes can also be used. It is included in the technical scope of the present invention.

  DESCRIPTION OF SYMBOLS 10 ... Vehicle, 11 ... Steering, 21 ... Steering angle sensor, 100 ... ECU, 101 ... Steering information acquisition part, 102 ... Target steering torque calculation part, 102a ... Inertial force calculation part, 102b ... Characteristic correction part,

Claims (1)

An inertial force specifying means for specifying the inertial force of the steering wheel;
A steering apparatus comprising: a characteristic correction unit that corrects a characteristic of a steering angular acceleration of the steering wheel according to the specified inertial force.

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