JP2014237376A - Steering control device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a steering control device capable of adjusting steering feeling by an operation which a driver can intuitively understand.SOLUTION: A steering control device controls steering characteristic by outputting, using a motor, an assist torque corresponding to a steering torque applied to a steering shaft connected to a steering member. Adjustment torque generating means (24, 25, 26) generates adjustment torque for adjusting a mechanical impedance that regulates relation between a steering angle and the steering torque that is applied to the steering shaft. Command value generation means (21, 22, 27, 28, 29) generates a command value for controlling the motor based on the adjustment torque generated by the adjustment torque generation means. Index value generation means generates a steering feeling index value that represents steering feeling which a driver receives at the time of steering with the steering member. Then, the adjustment torque generation means, based on the steering feeling index value generated by the index value generation means, generates an adjustment torque for adjusting the mechanical impedance.

Description

  The present invention relates to a steering control device that adjusts a steering feeling using an assist torque.

  Conventionally, it is known that a driver can grasp the state of a vehicle from a steering feeling (hand feeling). The way of feeling the steering feel varies from driver to driver, and also varies depending on changes in the road surface condition. Therefore, development of a device that adjusts the steering feel is underway. As this type of device, there is a device that adjusts a steering feeling by a driver setting parameters in a steering characteristic diagram that is set in advance (see, for example, Patent Document 1).

Japanese Patent No. 4461630

  The above-mentioned steering characteristic diagram shows the relationship between parameters such as steering torque and steering angle, which are parameters representing the turning state of the steering, and the motor current of the motor that generates assist torque for adjusting the steering feeling. It is.

  However, it is intuitive for the driver to adjust the steering feeling in consideration of how the steering feeling changes when the motor current of the motor that is a part of the vehicle is changed. There was a problem that it was difficult to do.

  The present invention has been made in view of such problems, and an object of the present invention is to provide a steering control device that adjusts the steering feeling by an operation that is easy for the driver to understand intuitively.

  The steering control device according to claim 1, wherein the steering characteristic is controlled by outputting an assist torque corresponding to a steering torque applied to a steering shaft connected to a steering member by a motor. It is. The adjustment torque generating means generates an adjustment torque for adjusting the mechanical impedance that defines the relationship between the steering torque and the steering angle.

  The command value generation means generates a command value for controlling the motor based on the adjustment torque generated by the adjustment torque generation means. The index value generating means generates a steering feeling index value indicating a steering feeling received by the driver when the steering member is steered. In particular, the adjustment torque generating means generates an adjustment torque for correcting the mechanical impedance based on the steering feeling index value.

  According to such a configuration, since the steering feeling index value indicating the steering feeling received by the driver is used as an index for adjusting the steering characteristics, the driver and the operator who intends to adjust the steering characteristics can perform steering intuitively and intuitively. Characteristics can be adjusted.

  In addition, the code | symbol in the parenthesis described in the claim shows the correspondence with the specific means as described in embodiment mentioned later as one aspect, Comprising: The technical scope of this invention is limited is not.

It is a block diagram which shows schematic structure of an electric power steering system. It is a block diagram which shows the outline of the control mechanism of ECU. It is a block diagram which shows the structure of a base assist part. It is explanatory drawing which shows an example of a steering feeling parameter | index. It is a block diagram which shows the structure of a load estimator. It is a graph which illustrates the characteristic of a rigidity base map. It is a graph which illustrates the characteristic of a rigid weight correction map. It is a graph which illustrates the characteristic of a rigidity hardness correction map. It is a graph which illustrates the characteristic of a rigid friction correction map. (A) is a graph illustrating the characteristics of the stiffness adjustment map, and (b) shows how the transmission characteristics from the steering torque to the steering angle change by changing the coefficient corresponding to the stiffness coefficient according to the stiffness adjustment map. FIG. It is a block diagram which shows schematic structure of an parameter | index production | generation part. It is a flowchart explaining the process (steering feeling setting process) which an index control part performs. It is explanatory drawing which shows an example of a display of an input part (touch panel display).

An embodiment of the present invention will be described below with reference to the drawings.
<Overall configuration>
As shown in FIG. 1, the electric power steering system 1 of the present embodiment assists an operation of a handle (steering member) 2 by a driver with a motor 6. The handle 2 is fixed to one end of a steering shaft 3, and a torque sensor 4 is connected to the other end of the steering shaft 3, and an intermediate shaft 5 is connected to the other end of the torque sensor 4. In the following description, the entire shaft body from the steering shaft 3 through the torque sensor 4 to the intermediate shaft 5 is also collectively referred to as a steering shaft. Hereinafter, the rotation angle of the steering shaft is also referred to as a steering angle, the rotation angular velocity of the steering shaft is also referred to as steering speed, and the rotation angular acceleration of the steering shaft is also referred to as steering acceleration.

  The torque sensor 4 is a sensor for detecting the steering torque Ts. Specifically, a torsion bar that connects the steering shaft 3 and the intermediate shaft 5 is provided, and a torque applied to the torsion bar is detected based on a twist angle of the torsion bar.

  The motor 6 assists the steering force of the handle 2 and its rotation is transmitted to the intermediate shaft 5 via the speed reduction mechanism 6a. That is, the speed reduction mechanism 6a is constituted by a worm gear provided at the tip of the rotating shaft of the motor 6 and a worm wheel provided coaxially on the intermediate shaft 5 in mesh with the worm gear. The rotation of the motor 6 is transmitted to the intermediate shaft 5. Conversely, when the intermediate shaft 5 is rotated by the operation of the handle 2 or the reaction force from the road surface (road surface reaction force), the rotation is transmitted to the motor 6 via the speed reduction mechanism 6a, and the motor 6 also rotates. .

  The motor 6 is a brushless motor in the present embodiment, and includes a rotation sensor such as a resolver, and is configured to output the rotation state of the motor 6. The motor 6 of the present embodiment is configured to be capable of outputting at least the motor speed ω (information indicating the rotational angular speed) as the rotational state from the rotation sensor. Instead of the motor speed ω, a steering speed obtained by multiplying the motor speed ω by the gear ratio of the speed reduction mechanism 6a may be used.

  The other end of the intermediate shaft 5 opposite to the end to which the torque sensor 4 is connected is connected to the steering gear box 7. The steering gear box 7 is configured by a gear mechanism including a rack and a pinion gear, and the rack teeth mesh with a pinion gear provided at the other end of the intermediate shaft 5. Therefore, when the driver turns the handle 2, the intermediate shaft 5 rotates (that is, the pinion gear rotates), thereby moving the rack to the left and right. Tie rods 8 are attached to both ends of the rack, and the tie rods 8 reciprocate left and right together with the rack. Accordingly, the tie rod 8 pulls or pushes the knuckle arm 9 ahead, thereby changing the direction of each tire 10 that is a steered wheel.

A vehicle speed sensor 11 for detecting the vehicle speed V is provided at a predetermined part of the vehicle.
With this configuration, when the driver rotates (steers) the handle 2, the rotation is transmitted to the steering gear box 7 via the steering shaft 3, the torque sensor 4, and the intermediate shaft 5. Then, in the steering gear box 7, the rotation of the intermediate shaft 5 is converted into the left-right movement of the tie rod 8, and the left and right tires 10 are steered by the movement of the tie rod 8.

  Hereinafter, the entire mechanism that transmits the steering force of the handle 2 from the handle 2 to the tire 10 is referred to as a steering system mechanism 100. The steering system mechanism 100 is controlled by a steering control unit 50 including the ECU 15 and the index generation unit 16 (that is, the steering system mechanism 100 refers to the entire mechanism excluding the steering control unit 50 in the system configuration diagram shown in FIG. 1). ).

<ECU>
The ECU 15 is operated by electric power from an in-vehicle battery (not shown), and assist torque based on the steering torque Ts detected by the torque sensor 4, the motor speed ω of the motor 6, and the vehicle speed V detected by the vehicle speed sensor 11. Command Ta is calculated. Then, by applying a drive voltage Vd corresponding to the calculation result to the motor 6, the assist amount of the force with which the driver turns the steering wheel 2 (and thus the force to steer both tires 10) is controlled.

  In the present embodiment, since the motor 6 is a brushless motor, the drive voltage Vd output (applied) from the ECU 15 to the motor 6 is specifically the three-phase (U, V, W) drive voltages Vdu, Vdv, Vdw. is there. The rotational torque of the motor 6 is controlled by applying the drive voltages Vdu, Vdv, Vdw of these phases from the ECU 15 to the motor 6 (energizing the drive current of each phase). A method for driving a brushless motor with a three-phase drive voltage (for example, PWM drive) and a drive circuit (for example, a three-phase inverter) for generating the three-phase drive voltage are well known. Omitted.

  The ECU 15 controls the motor 6 by directly controlling the drive voltage Vd applied to the motor 6, but the steering system mechanism 100 driven by the motor 6 as a result by controlling the motor 6. Therefore, the control object of the ECU 15 can be said to be the steering system mechanism 100.

<Control by ECU>
Next, a schematic configuration (control mechanism) of the ECU 15 will be described based on the block diagram of FIG. Note that, in the control mechanism of the ECU 15 shown in FIG. 2, each part except the current feedback (FB) unit 42 and part of the functions of the current FB unit 42 are actually determined by a CPU (not shown) included in the ECU 15. This is realized by executing a control program. That is, FIG. 2 shows various functions realized by the CPU divided into functional blocks. However, it is only an example that the control mechanism shown in each figure is realized by software, and the whole or a part of the control mechanism shown in FIG. 2 or the like is realized by hardware such as a logic circuit. Needless to say, it may be.

  As shown in FIG. 2, the ECU 15 adds the base assist unit 20 that generates the base assist command Tb *, the correction unit 30 that generates the correction torque command Tr, and the base assist command Tb * and the correction torque command Tr. And an adder 41 for generating an assist torque command Ta, and a current feedback (FB) unit 42 for energizing and driving the motor 6 by applying a drive voltage Vd to the motor 6 based on the assist torque command Ta. .

  The base assist unit 20 realizes the characteristic of the steering reaction force (steering torque) according to the road surface reaction force (road surface load), that is, the reaction (reaction force) corresponding to the road surface load is transmitted quasi-steadily to the driver. This makes it easier for the driver to grasp the vehicle condition and road surface condition, and adjusts the feeling (feeling hardness, stickiness, weight from the steering wheel to the tire) given to the driver according to the steering condition. This is a block for realizing an improvement in steering feeling. The base assist unit 20 is based on the steering torque Ts, the motor speed ω, the vehicle speed V, and the steering feeling index values (u1, u2, u3) output from the index generation unit 16, and the transmission feeling corresponding to the road load described above. A base assist command Tb * for assisting the operation of the steering wheel 2 so as to realize a steering feeling corresponding to the steering state is generated.

  The correction unit 30 follows the driver's intention (specifically, the vehicle properly converges or generates a smooth vehicle turn, etc.) in accordance with the vehicle motion characteristics and the steering mechanism transmission to the driver's steering operation. It is a block to do. The correction unit 30 generates a correction torque command Tr for suppressing (converging) the above-described unstable behavior based on the steering torque Ts, the motor speed ω, and the vehicle speed V.

  The adder 41 generates an assist torque command Ta by adding the base assist command Tb * generated by the base assist unit 20 and the correction torque command Tr generated by the correction unit 30.

  Based on the assist torque command Ta, the current FB unit 42 is configured so that an assist torque (assist steering force) corresponding to the assist torque command Ta is applied to the steering shaft (particularly on the tire 10 side with respect to the torque sensor 4). A drive voltage Vd is applied. Specifically, a target current (target current for each phase) to be energized to each phase of the motor 6 is set based on the assist torque command Ta. Then, by detecting and feeding back the energization current Im of each phase and controlling the drive voltage Vd (controlling the energization current) so that the detected value (the energization current Im of each phase) matches the target current, A desired assist steering force is generated with respect to the steering shaft.

  The correction unit 30 and the current FB unit 42 are known techniques (see, for example, Japanese Patent Application Laid-Open No. 2013-52793), and thus description thereof is omitted here. The following description relates to the main part of the present invention. The base assist unit 20 will be described in detail.

<Base assist part>
As shown in FIG. 3, the base assist unit 20 includes a load estimator 21, a basic load amount calculation unit 22, a driver work rate calculation unit 23, a stiffness adjustment amount calculation unit 24, and a viscosity adjustment amount calculation unit 25. The inertia adjustment amount calculation unit 26, the differentiator 261, the target calculation unit 27, the deviation calculation unit 28, the controller unit 29, and the storage unit 71 are provided.

  The load estimator 21 estimates the road load based on the base assist command Tb * (corresponding to the assist torque) and the steering torque Ts. The basic load amount calculation unit 22 is a basic component that is a basic component of the target value of the steering torque based on the road surface load (estimated load Tx) estimated by the load estimator 21 and the traveling speed (vehicle speed V) of the host vehicle. Torque Tf * is generated.

  The driver power calculation unit 23 calculates the driver power W by multiplying the steering speed obtained by multiplying the motor speed ω by the gear ratio of the speed reduction mechanism 6a by the steering torque Ts. However, the steering torque Ts and the motor speed ω (and thus the steering speed) both have opposite polarities when the handle 2 is rotated clockwise and when it is rotated counterclockwise. Further, the steering torque Ts has a reverse polarity value when the steering wheel 2 is rotated clockwise from the neutral position and counterclockwise when the position of the handle 2 where Ts = 0 is set to the neutral position. The neutral position is a position where the vehicle is moved straight during normal driving when the tire is gripped, and a neutral position is a direction in which the tire slides when a spin is caused by oversteer. Here, it is assumed that it is positive when rotating right and negative when rotating left.

  Therefore, when the steering torque Ts and the motor speed ω have the same polarity and the driver power W is positive, it is a value generated by the operation of turning the steering wheel, and the polarity of the steering torque Ts and the motor speed ω is different. When the driver power W is negative, it indicates that the value is generated by the operation of turning back the steering wheel. If the driver power W is zero, the steering power is maintained.

  That is, when the steering wheel is cut to the left or right from the neutral position, the polarities of the steering torque Ts and the motor speed ω are the same, so the driver power W has a positive value. If it is held with the steering wheel turned off (steering state), the motor speed ω is zero, so the driver power is zero. When the steering wheel is turned back from this state of steering holding, the polarity of the motor speed ω is reversed from that when the steering wheel is turned, and the polarity of the steering torque Ts and the motor speed ω are different from each other. Is a negative polarity value. Note that the steering torque Ts increases as the tire direction deviates from the traveling direction of the vehicle, and increases as the motor speed ω steers more rapidly, and depends on the degree of these operations (operation amount). The absolute value of the driver work rate W takes a large value.

  Since the steering speed is a value proportional to the motor speed ω, the motor speed ω may be regarded as the steering speed, and the motor speed ω multiplied by the steering torque Ts may be used as the driver work rate W.

The differentiator 261 generates a motor acceleration α corresponding to the steering acceleration by differentiating the motor speed ω corresponding to the steering speed.
The storage unit 71 stores the index values (u1, u2, u3) of the steering feeling index input from the index generation unit 16, and stores the stored index values (u1, u2, u3) as the stiffness coefficient calculation unit 24a, the viscosity. It outputs to the coefficient calculating part 25a and the inertia coefficient calculating part 26a. The steering feeling index values (u1, u2, u3) stored in the storage unit 71 are updated by the output from the index generation unit 16.

  The steering feeling index is an index for adjusting the steering feeling set so that the driver can intuitively and intuitively understand. In this embodiment, as shown in FIG. Three indicators of “hardness” and “friction” are used. In the following, a weight index value u1 that is an index value for “weight”, a hardness index value u2 that is an index value for “hardness”, and a friction index value u3 that is an index value for “friction”. Collectively, they are referred to as steering feeling index values (u1, u2, u3).

  Returning to FIG. 3, the stiffness adjustment amount calculation unit 24 includes the adjustment included in the target steering torque Ts * based on the driver work rate W, the estimated load Tx, the vehicle speed V, and the steering feeling index values (u1, u2, u3). It is one of the components, and generates a rigidity adjustment torque Tk * for adjusting the rigidity feeling of the steering system mechanism 100 given to the driver during steering. The viscosity adjustment amount calculation unit 25 adjusts an adjustment component (adjustment torque) included in the target steering torque Ts * based on the driver work rate W, the motor speed ω, the vehicle speed V, and the steering feeling index value (u1, u2, u3). And a viscosity adjustment torque Tc * for adjusting the viscosity of the steering system mechanism 100 given to the driver during steering. The inertia adjustment amount calculation unit 26 is one of the adjustment components included in the target steering torque Ts * based on the driver power W, the motor acceleration α, and the steering feeling index values (u1, u2, u3). An inertia adjustment torque Ti * for adjusting the inertial feeling of the steering system mechanism 100 that is sometimes given to the driver is generated.

  The target calculator 27 calculates the target steering torque Ts * by adding the basic torque Tf *, the rigidity adjustment torque Tk *, the viscosity adjustment torque Tc *, and the inertia adjustment torque Ti *. The deviation calculator 28 calculates a torque deviation which is a difference between the steering torque Ts and the target steering torque Ts *. The controller unit 29 includes a differentiator, an integrator, and the like, and generates an output for adjusting a feeling of transmission according to the road load applied to the driver during steering operation and a feeling of steering according to the steering state amount.

  Based on the torque deviation (difference between the steering torque Ts and the target steering torque Ts *), the controller unit 29 performs control so that the torque deviation becomes zero, that is, the steering torque Ts follows the target steering torque Ts *. Thus, a base assist command Tb * is generated for generating an assist torque (also referred to as an assist amount) that realizes a feeling of transmission according to the road surface load and a feeling of steering according to the steering state amount.

  As shown in FIG. 5, the load estimator 21 includes an adder 21a that adds a base assist command Tb * and a steering torque Ts, and a low-pass filter (LPF) that extracts a component in a band below a predetermined frequency from the addition result. ) 21b, and the frequency component extracted by the LPF 21b is output as the estimated load Tx. Usually, since the driver mainly operates by relying on the steering reaction force information of 10 Hz or less, the LPF 21 b passes (extracts) the frequency component of approximately 10 Hz or less so as to block the frequency component higher than 10 Hz. Is set.

  Returning to FIG. 3, the basic load amount calculator 22 allows the driver to feel that the steering operation is heavy or light according to the road surface reaction force, or the driver's steering reaction force against an increase in the road surface reaction force. The target steering torque Ts * for realizing the degree of increase (gradient) of (or steering torque) is generated. The basic load amount calculation unit 22 of the present embodiment actually maps the target steering torque Ts * corresponding to the estimated load Tx and the vehicle speed V, and generates the target steering torque Ts * based on the map. To do.

  Incidentally, the mechanical impedance (stiffness coefficient, viscosity coefficient, inertia coefficient) defines the relationship between the force F applied to the object and the displacement amount x of the object, and is represented by the relational expression (1). In particular, in the case of rotational motion, F is regarded as the torque applied to the object, and x is regarded as the amount of rotation of the object.

x represents a steering angle (rotation angle of the motor), a first differential value represents a steering speed (motor speed ω), and a second differential represents a steering acceleration (motor acceleration α). In other words, the stiffness adjustment amount calculation unit 24, the viscosity adjustment amount calculation unit 25, and the inertia adjustment amount calculation unit 26 are torques required for adjusting the steering feeling given to the driver when operating the steering wheel according to the equation (1) (hereinafter referred to as steering feeling adjustment torque). The steering feeling adjustment torque Tsf * is equivalent to a torque obtained by adding a rigidity adjustment torque Tk *, a viscosity adjustment torque Tc *, and an inertia adjustment torque Ti *.

  However, in the present embodiment, as shown in the equation (2), since the estimated load Tx is used instead of the steering angle x for calculating the stiffness adjustment torque Tk *, it corresponds to the stiffness coefficient instead of the stiffness coefficient. A stiffness equivalent coefficient K is used. The relationship between the steering angle x and the stiffness equivalent coefficient K can be easily obtained from a relational expression representing the characteristics of the steering system mechanism 100.

The stiffness adjustment amount calculation unit 24 includes a stiffness coefficient calculation unit 24a and a multiplier 24b.
The stiffness coefficient calculation unit 24a corresponds to stiffness for adjusting the stiffness feeling (spring feeling) given to the driver when operating the steering wheel according to the driver power W, the vehicle speed V, and the steering feeling index value (u1, u2, u3). A coefficient K (a value corresponding to a stiffness coefficient of mechanical impedance, see formula (2)) is generated. The multiplier 24b generates the stiffness adjustment torque Tk * by multiplying the stiffness equivalent coefficient K by the estimated load Tx. That is, the stiffness equivalent coefficient K can be said to be an adjustment coefficient for the road surface load (estimated load Tx).

  For simplicity, the case where the vehicle speed V is a certain value will be described below. As shown in the equations (3a) to (3c), the stiffness coefficient calculation unit 24a uses the basic stiffness equivalent coefficient K0 prepared in advance according to the driver power W as a steering feeling index value (u1, u2, u3). The stiffness equivalent coefficient K is generated by adjusting with the additional stiffness equivalent coefficients K1, K2, and K3 generated corresponding to

Stiffness (W), BaseMap (W), AddMap1 (W), AddMap2 (W), and AddMap3 (W) may be prepared as a function of the driver work rate W or may be prepared as a map. In the present embodiment, these are prepared as maps, and are sequentially referred to as a stiffness adjustment map, a stiffness base map, a stiffness weight addition map, a stiffness hardness addition map, and a stiffness friction addition map. That is, in this embodiment, the weights of the stiffness weight addition map, the stiffness hardness addition map, and the stiffness friction addition map used when generating the stiffness equivalent coefficient K are changed according to the steering feeling index value (u1, u2, u3). I am letting.

  For example, the rigidity base map shown in FIG. 6 is used, and the rigidity weight addition map, the rigidity hardness addition map, and the rigidity friction addition map shown in FIGS. 7 to 9 are used. Here, as shown in FIG. 8, the rigidity / hardness addition map is set to increase the rigidity at a predetermined rate according to the incision of the handle (W> 0) with respect to the increase in the hardness index value u2. Yes.

  The stiffness adjustment map is a combination of these maps. For example, the steering feeling index values (u1, u2, u3) are set to u1 = 0.6, u2 = 0.8, u3 = −0.25. (See FIG. 4, hereinafter referred to as a correction mode), the map shown in FIG. In this case, compared with the case where the steering feeling index values (u1, u2, u3) are set to u1 = 0, u2 = 0, u3 = 0 (hereinafter referred to as the reference mode), the steering of the steering wheel (W> 0) ), The rigidity increases, and a sense of “hardness” is added. Also, a Bode diagram showing how the transmission characteristic from the steering torque to the steering angle changes by changing the coefficient corresponding to the stiffness coefficient according to this stiffness adjustment map is as shown in FIG.

  Here, the transfer characteristics in each mode when the driver power is 30 W are shown. The part where the characteristic of the stiffness coefficient is expressed in the transfer characteristic, that is, the steady gain is smaller in the correction mode. Since the steady gain decreases as the rigidity increases, it can be seen from the rigidity adjustment map that the rigidity is surely adjusted.

  Note that the maps shown in FIGS. 6 to 10 show the case where the vehicle speed V is a certain value as described above. Therefore, in practice, the characteristics shown in the above map vary depending on the vehicle speed V.

  The viscosity adjustment amount calculation unit 25 includes a viscosity coefficient calculation unit 25a and a multiplier 25b. The viscosity coefficient calculation unit 25a calculates a viscosity coefficient C used for adjusting the viscosity feeling given to the driver during the steering operation according to the driver power W, the vehicle speed V, and the steering feeling index value (u1, u2, u3). Generate. The multiplier 25b generates the viscosity adjustment torque Tc * by multiplying the viscosity coefficient C by the motor speed ω corresponding to the steering speed (see equation (2)).

  Similar to the stiffness equivalent coefficient K, the viscosity coefficient calculation unit 25a generates a basic viscosity coefficient C0 prepared in advance corresponding to the steering feeling index value (u1, u2, u3) according to the driver power W. The viscosity coefficient C is generated by adjusting with the additional viscosity coefficients C1, C2, and C3 (see equation (3)). In this embodiment, the basic viscosity coefficient C0 and the additional viscosity coefficients C1, C2, and C3 are respectively generated using a viscosity base map, a viscosity weight addition map, a viscosity hardness addition map, and a viscous friction addition map prepared in advance. Is done.

  In other words, the viscosity coefficient calculation unit 25a weights the viscosity weight addition map, the viscosity hardness addition map, and the viscous friction addition map used when generating the viscosity coefficient C by using the steering feeling index values (u1, u2, u3). It is adjusted by. Similar to the stiffness equivalent coefficient K, the viscosity coefficient C varies with the vehicle speed V.

  The inertia adjustment amount calculation unit 26 includes an inertia coefficient calculation unit 26a and a multiplier 26b. The inertia coefficient calculation unit 26a uses an inertia adjustment map for the inertia coefficient I for adjusting the inertia feeling given to the driver during the steering operation according to the driver power W and the steering feeling index value (u1, u2, u3). To generate. The multiplier 26b calculates the inertia adjustment torque Ti * by multiplying the motor acceleration α generated by the differentiator 261 by the inertia coefficient I.

  Similar to the stiffness equivalent coefficient K, the inertia coefficient calculation unit 25a generates a basic inertia coefficient I0 prepared in advance corresponding to the steering feeling index values (u1, u2, u3) in accordance with the driver power W. The inertial coefficient I is generated by adjusting the additional inertial coefficients I1, I2, and I3 (see the equation (3)). In this embodiment, the basic inertia coefficient I0 and the additional inertia coefficients I1, I2, and I3 are respectively generated using an inertia base map, an inertia weight addition map, an inertia hardness addition map, and an inertia friction addition map that are prepared in advance. Is done.

  That is, the inertia coefficient calculation unit 26a uses the weight of the inertia weight addition map, inertia hardness addition map, and inertia friction addition map used when generating the inertia coefficient I as steering feeling index values (u1, u2, u3). It is adjusted by. Here, unlike the stiffness equivalent coefficient K and the viscosity coefficient C, the inertia coefficient I does not change with the vehicle speed V. However, as a parameter for changing the inertia coefficient I, the vehicle speed V may be used in addition to the driver work factor W, similarly to the stiffness equivalent coefficient K and the viscosity coefficient C.

  As described above, the stiffness adjustment amount calculation unit 24, the viscosity adjustment amount calculation unit 25, and the inertia adjustment amount calculation unit 26 are, as shown in the equations (4a) to (4c), the steering feeling index stored in the storage unit 71. The stiffness equivalent coefficient K, viscosity coefficient C, and inertia coefficient I (basic adjustment characteristics) of the mechanical impedance expressing the steering feeling adjustment torque Tsf * are adjusted so as to correspond to the values (action index values) (u1, u2, u3). doing.

<Indicator generator>
The index generation unit 16 is configured to generate a steering feeling index value (u1, u2, u3) and to output (write) the generated steering feeling index value (u1, u2, u3) to the ECU 15.

  Specifically, as shown in FIG. 11, the index generation unit 16 is a transmission / reception unit that performs communication between an input unit 65 to which a setting command from a driver or an operator is input and an external server 80 that is an external storage device. 66 and an index control unit 60 that receives a setting command output from the input unit 65, sets a steering feeling index value according to the setting command, and outputs (writes) the steering feeling index value to the ECU 15. The input unit 65 is composed of a touch panel display operated by a driver, and the transmission / reception unit 66 is composed of a wireless communication device.

<Control by index control unit>
The index control unit 60 is composed of a known microcomputer including a CPU 61, a ROM 62, a RAM 63, and the like. For example, the index control unit 60 executes a steering feeling setting process triggered by the selection of a steering feeling setting mode button (not shown) by the operation of the touch panel display 65 by the driver. Next, the steering feeling setting process will be described using the flowchart shown in FIG. 12 and an example of the display on the touch panel display 65 shown in FIG.

  First, in S110, the screen of the touch panel display 65 is switched as shown in FIG. Here, on the left side of the screen, a list of names of steering feeling modes (hereinafter referred to as a steering feeling mode list) such as “sport mode”, “luxury mode”, “snow mode”, “custom mode”, etc. is displayed. To do. In addition, an operation mode switching button for switching to each operation mode of “download”, “upload”, “edit”, and “decision” is displayed at the bottom of the screen.

  When one of the steering feeling mode lists is selected by operating the cursor by the driver, on the right side of the screen, the description of the steering feeling mode selected by the cursor (mode explanation) and the steering feeling in this steering feeling mode are displayed. The index values (u1, u2, u3) are displayed. The steering feeling mode list data, that is, the names of the respective steering feeling modes, the mode descriptions corresponding thereto, and the steering feeling index values (u1, u2, u3) are stored in the RAM 63 in advance.

  On the screen, if the steering feeling index is, for example, “weight”, a straight line indicating a level from light to heavy, if “hardness”, a straight line indicating a level from soft to hard, “friction” If so, a straight line indicating the level from clean to moist is displayed, and a marker is displayed on the straight line at a position indicating the level of the steering index. In the present embodiment, for example, for the steering feeling index “weight”, index values are assigned such that “light” = − 1, “heavy” = 1, and middle = 0. Similarly, index values in the range of 1 to −1 are assigned to the steering feeling indexes of “hardness” and “friction”. That is, the index value corresponding to the marker position corresponds to the steering feeling index value.

  Next, in S115, it is determined whether any one of the steering feeling mode lists has been selected. Specifically, it is determined whether or not the “OK” button is selected in a state where any one of the steering feeling modes is selected with the cursor. If the “OK” button is selected, the process proceeds to S130. On the other hand, if the “OK” button is not selected, the process proceeds to S120. Hereinafter, the steering feeling mode selected by the cursor when the “OK” button is selected is referred to as a selected steering feeling mode.

  In continuing S120, it is judged whether download is performed. Specifically, it is determined whether or not the “download” button is selected within a predetermined time. If the “download” button is selected within the predetermined time, the process proceeds to S125. On the other hand, if the “download” button is not selected within a predetermined time, this process is terminated.

  In S125, which is shifted to when the “Download” button is selected in S120, the detailed data regarding the steering feeling mode stored in the external server 80 using the transmission / reception unit 66 (the name of the steering feeling mode, the mode for the mode). Download of the existing steering feeling data which is the description and steering feeling index values (u1, u2, u3)) is executed. Then, the steering feeling mode list data stored in the RAM 63 is updated so that the downloaded existing steering feeling data is added. Thereafter, the process proceeds to S110.

  In S130, which is shifted to when the steering feeling mode is selected in S115, it is determined whether or not to execute upload. Specifically, it is determined whether or not an “upload” button has been selected. If the “upload” button is selected, the process proceeds to S135. In S <b> 135, detailed data regarding the selected steering feeling mode is uploaded to the external server 80 using the transmission / reception unit 66.

  In S140, the process proceeds to S140 when the "Upload" button is not selected in S130, it is determined whether or not to accept editing. Specifically, it is determined whether or not the “edit” button is selected. If the “edit” button is selected here, the process proceeds to S150. On the other hand, if the “edit” button is not selected, the process proceeds to S145. In S145, the steering feeling index values (u1, u2, u3) are output to the ECU 15 for the selected steering feeling mode. Then, this process ends.

  In S150, which is shifted to when the “Edit” button is selected in S140, a window for allowing the driver to input a new recognition name (hereinafter referred to as a new recognition name) is displayed, and the new recognition input in the window is displayed. The name, the mode description of the selected steering feeling mode, and the steering feeling index values (u1, u2, u3) are stored in the RAM 63 as detailed data of the steering feeling mode of the new name. And the detailed data of the steering feeling mode of a new recognition name is displayed on the right screen of a touch panel display.

  In subsequent S155, the marker indicating the level of the steering feeling index can be moved left and right, and an index value corresponding to the marker position is newly acquired as the steering feeling index value and stored in the RAM 63. Accordingly, the driver can easily set the steering feeling index value by sliding the marker left and right.

  Also, in S155, when the location where the mode description is displayed is selected by the cursor, a window for editing the mode description is displayed, and the contents input in the window are stored in the RAM 63 as a new mode description. As a result, the driver can easily edit the mode description by selecting the portion where the mode description is displayed with the cursor and performing input in the displayed window.

  Next, in S160, it is determined whether or not to change to the edited steering feeling mode (steering feeling mode of a newly recognized name). Specifically, it is determined whether or not the “OK” button has been selected. If the “OK” button is not selected here, the process proceeds to S110. On the other hand, when the “OK” button is selected, the process proceeds to S165. In S165, the steering feeling index value (u1, u2, u3) in the steering feeling mode of the newly recognized name is output to the ECU 15. Then, this process ends.

  That is, the index control unit 60 selects an existing steering feeling mode stored in the RAM 63 according to the operation of the cursor, the operation mode switching button, and the marker by the driver, and the steering index value (u1, u2, u3) of the mode. Is output to the ECU 15, the existing steering feeling data is downloaded from an external server, the steering index values (u1, u2, u3) of the data are output to the ECU 15, and the existing and downloaded steering feeling mode data are edited. Then, a process of outputting the steering index values (u1, u2, u3) of the edited steering feeling data to the ECU 15 as new edited steering feeling data is executed.

<Effect>
As described above, in this embodiment, as the steering feeling index for adjusting the steering characteristic, an index indicating the steering feeling received by the driver, such as “weight”, “hardness”, and “friction”, is used. These steering feeling indexes are associated with mechanical impedance characteristics. The steering control unit 50 is configured to realize the associated mechanical impedance characteristic by motor control.

  For this reason, by setting the steering feeling index values (u1, u2, u3), compared with a conventional apparatus that sets parameters that are not directly related to the steering feeling (for example, mechanical parameters such as motor current and steering angle ratio). Thus, the steering characteristics can be adjusted more quickly, sensibly and intuitively.

  In the present embodiment, the index generation unit 16 receives a setting command from the driver (operator) via the touch panel display 65, and adjusts the steering feeling index values (u1, u2, u3) according to the received setting command. It is configured. Thus, the steering feeling can be set according to the preference of the driver (operator) according to the adjusted index value (operator setting index value). Further, by using the touch panel display 65, the driver (operator) can easily adjust the steering feeling.

  In the present embodiment, the index generation unit 16 is configured to download the existing steering feeling data stored in the external server 80 by the transmission / reception unit 66. And it is comprised so that a steering characteristic may be set based on the steering feeling index value (predetermined index value) in the downloaded existing steering feeling data. Further, the index generation unit 16 adjusts (edits) the downloaded existing steering feeling data to newly generate edited steering feeling data, and based on the steering feeling index value (operator setting index value) in the edited steering feeling data. The steering characteristic is set.

  Thereby, for example, compared with the case where the steering index value is adjusted for several types of modes stored in advance in the ROM, a change in a running pattern by a road such as an urban area, a winding road, and a highway, a change in a road surface condition due to rain or snow, It is possible to set steering characteristics adapted to various driving situations. Further, it is possible to set a steering characteristic that more precisely corresponds to the gender, age, and preference of the driver (operator).

  In the present embodiment, the index generation unit 16 is configured to upload editing steering feeling data to the external server 80 by the transmission / reception unit 66. Thereby, editing steering feeling data can be shared with other drivers (operators).

  In the present embodiment, the electric power steering system 1 is configured such that the base assist unit 20 transmits the reaction force corresponding to the road surface load (estimated load Tx) to the driver and the steering system mechanism 100 according to the driver power W. A base assist command Tb * for controlling the motor 6 that is the source of assist torque is generated from the component that adjusts the mechanical impedance.

  As a result, the electric power steering system 1 can accurately provide the driver with a feeling of transmission according to the road load and a feeling of steering according to the steering state when operating the steering wheel. In addition, since the driver power W that can identify the steering state such as cutting, switching back, and holding is used as a parameter for changing the mechanical impedance, there is no need to switch the control for each steering state, and the simple control makes it fine. It is possible to adjust the steering feeling.

<Correspondence with claims>
A steering control unit 50 including the ECU 15 and the index generation unit 16 corresponds to a steering control device. The index generation unit 16 corresponds to an index value generation unit, the driver work rate calculation unit 23 corresponds to a steering state amount generation unit, and a stiffness adjustment amount calculation unit 24, a viscosity adjustment amount calculation unit 25, and an inertia adjustment amount calculation unit 26 The load estimator 21, the basic load amount calculator 22, the target calculator 27, the deviation calculator 28, and the controller 29 correspond to the command value generator.

The touch panel display 65 corresponds to an input unit, the transmission / reception unit 66 corresponds to an upload unit, and the storage unit 71 corresponds to a storage unit.
<Other embodiments>
As mentioned above, although embodiment of this invention was described, it cannot be overemphasized that this invention can take a various form, without being limited to the said embodiment. For example, the functions of one component may be distributed to a plurality of components, or the functions of a plurality of components may be integrated into one component. Further, at least a part of the configuration of the above embodiment may be replaced with a known configuration having the same function.

  The index generation unit 16 is not limited to the configuration shown in the above embodiment. The index generation unit may be an external device connected to the vehicle as necessary, or an existing device mounted on a vehicle such as an in-vehicle navigation device may have a function as an index generation unit. It may be realized. The input unit 65 may use, for example, existing various input devices mounted on the vehicle. Alternatively, the input unit 65 may be configured to use a mobile phone, and the index generation unit may be configured to output the steering feeling index value acquired by wireless communication using the mobile phone to the ECU 15. Further, when the input unit 65 is configured by a mobile phone, the mobile phone may be configured to have the function of the transmission / reception unit 66.

  In the above-described embodiment, three indicators of “weight”, “hardness”, and “friction” are used as the steering feeling indicators, but the steering feeling indicators and the number thereof are not limited thereto. The steering feeling index may be an index that is directly related to the feeling received by the driver by the operation of the steering member.

  In the above embodiment, the driver power W that is the product of the steering torque Ts and the steering speed (motor speed ω) is used as a parameter for changing the mechanical impedance. However, the present invention is not limited to this. Any steering state quantity may be used as long as it is obtained by the product of the first physical quantity that increases / decreases in response to the second physical quantity that increases / decreases in accordance with the rotation speed of the steering shaft. As the first physical quantity, in addition to the steering torque Ts used in the above embodiment, a yaw rate, a lateral acceleration, a steering angle, or the like may be used. Further, the second physical quantity may be a displacement speed of a portion that is displaced in conjunction with the handle.

  In the embodiment described above, the assist torque command Ta supplied to the current FB unit 42 is obtained by adding the correction torque command Tr generated by the correction unit 30 to the base assist command Tb * generated by the base assist unit 20. The correction unit 30 may be omitted, and the base assist command Tb * may be directly used as the assist torque command Ta.

  In the embodiment described above, all of the stiffness coefficient, the viscosity coefficient, and the inertia coefficient are adjusted as the mechanical impedance. However, any one or any two of the coefficients may be adjusted.

  In the above embodiment, the load estimator 21 generates the estimated load Tx from the base assist command Tb * and the steering torque Ts, but the energization current Im detected by the current FB unit 42 instead of the base assist command Tb *. May be used.

In the above embodiment, the basic torque Tf * is generated from the estimated load Tx. However, the basic torque Tf * may be generated from the steering angle.
In the above embodiment, the basic torque Tf * and the mechanical impedance adjustment torques Tk *, Tc *, and Ti * are obtained separately, and then added to generate the target steering torque Ts *. The present invention may be applied to a system configured to obtain the target steering torque Ts * from the steering angle using a standard steering model reflecting impedance (see, for example, Japanese Patent No. 4232471). In this case, the mechanical impedance used in the reference steering model may be adjusted according to the steering state quantity (for example, driver power W).

  In the above embodiment, the example in which the present invention is applied to the EPS has been described. However, the present invention is not limited to this, and the present invention is applied to a steer-by-wire having a configuration in which the handle and the steering wheel are mechanically separated. May be. In this case, the target steering torque Ts * may be obtained by adding the rigidity adjustment torque Tk *, the viscosity adjustment torque Tc *, and the inertia adjustment torque Ti * without using the basic torque Tf *.

  DESCRIPTION OF SYMBOLS 1 ... Electric power steering system 2 ... Handle 3 ... Steering shaft 4 ... Torque sensor 5 ... Intermediate shaft 6 ... Motor 6a ... Deceleration mechanism 7 ... Steering gear box 8 ... Tie rod 9 ... Knuckle arm 10 ... Tire 11 ... Vehicle speed sensor 16 ... Index generation unit 20 ... base assist unit 21 ... load estimator 21a, 41 ... adder 21b ... LPF 22 ... basic load amount calculation unit 23 ... driver work rate calculation unit 24 ... stiffness adjustment amount calculation unit 24a ... stiffness coefficient calculation unit 24b , 25b, 26b ... multiplier 25 ... viscosity adjustment amount computing unit 25a ... viscosity coefficient computing unit 26 ... inertia adjustment amount computing unit 26a ... inertia coefficient computing unit 26b ... multiplier 27 ... target computing unit 28 ... deviation computing unit 29 ... controller Unit 30 ... Correction unit 41 ... Adder 42 ... Current feedback unit 50 ... steering characteristic adjustment system 60 ... steering control ECU 61 ... CPU 62 ... ROM 63 ... RAM 65 ... input unit (touch panel display) 66 ... transmission / reception unit 71 ... storage unit 80 ... external server 100 ... steering system mechanism 261 ... Differentiator

Claims (13)

A steering control device (15) for controlling steering characteristics by outputting an assist torque according to a steering torque applied to a steering shaft (3, 5) coupled to a steering member (2) by a motor (6),
Adjustment torque generating means (24, 25, 26) for generating an adjustment torque for adjusting a mechanical impedance defining a relationship between a steering torque applied to the steering shaft and a steering angle;
Command value generation means (21, 22, 27, 28, 29) for generating a command value for controlling the motor based on the adjustment torque generated by the adjustment torque generation means;
Index value generating means (16) for generating a steering feeling index value indicating a steering feeling received by the driver during steering of the steering member;
With
The steering control device, wherein the adjustment torque generation unit generates an adjustment torque for adjusting the mechanical impedance based on the steering feeling index value generated by the index value generation unit.   2. The command value generating means generates a target steering torque including at least the adjustment torque, and the command value is for causing the steering torque to follow the target steering torque. The steering control device described in 1.   The steering control device according to claim 2, wherein the target steering torque includes a basic torque.   The steering control device according to claim 3, wherein the basic torque is calculated using the assist torque.   The steering control device according to claim 4, wherein the basic torque has a value corresponding to a road load estimated from the assist torque and a steering torque applied to the steering member. Steering state quantity generating means (23) for generating a steering state quantity representing an operation applied to the steering member;
The steering control device according to any one of claims 1 to 5, wherein the adjustment torque generating means generates an adjustment torque for adjusting the mechanical impedance based on the steering state quantity.   The steering state quantity is a product of a first physical quantity that increases or decreases according to a rotation amount of the steering shaft and a second physical quantity that increases or decreases according to a rotation speed of the steering shaft. 6. The steering control device according to 6.   The steering control according to claim 7, wherein the steering state quantity is a driver power obtained by using the steering torque as the first physical quantity and an angular velocity of the steering shaft as the second physical quantity. apparatus.   The steering control device according to any one of claims 1 to 8, wherein the adjustment torque generation unit adjusts at least one of a stiffness coefficient, a viscosity coefficient, and an inertia coefficient as the mechanical impedance. .   The steering control device according to any one of claims 1 to 9, wherein the index value generating means generates a steering feeling index value by an external input.   The steering control device according to any one of claims 1 to 10, wherein the index value generation means generates a steering feeling index value by downloading a steering feeling index value stored externally.   The steering control device according to any one of claims 1 to 11, wherein the index value generating means includes an uploading means (66) for uploading the generated steering feeling index value to an external storage device. Storage means (71) for storing the steering feeling index value generated by the index value generating means,
The adjustment torque generation unit generates an adjustment torque for adjusting the mechanical impedance based on a steering feeling index value stored in the storage unit. The steering control device according to item.