JP2007090924A - Steering device for vehicle - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a steering device for a vehicle applying an appropriate reaction force when needed according to an operating state of a steering wheel by a driver. <P>SOLUTION: An electronic control unit 35 determines whether a steering wheel 11 performs a turning operation or not in S12, based on a steering angle θ input in S11. If the turning operation is performed, a basic reaction force torque map composed of an elastic torque Mte and a viscous torque Mtd is calculated in S13. The phase of a detection signal expressing the steering angle θ is compensated by using a phase compensating filter in S15, and a large target reaction force torque Tfa is calculated by using a phase compensated steering angle θ a in S15. On the other hand, if the turning operation is performed, a coefficient β for calculating the torque Mtd so as to be a small value is calculated in S16, 17. The torque Mtd is calculated in a map in S18, and a correction viscous torque Mtdh obtained by multiplying the viscous torque Mtd with the coefficient beta is calculated to calculate a small target reaction force torque Tfb in S19. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention includes a steering handle that is operated by a driver to steer a vehicle, a reaction force actuator that applies reaction torque to the operation of the steering handle, and a wheel that rotates according to the operation of the steering handle. The present invention relates to a steering-by-wire vehicle steering apparatus including a steering actuator for turning a steered wheel and a reaction force control device that controls driving of the reaction force actuator in accordance with an operation of the steering handle.

  In recent years, the development of steering devices that employ this type of steering-by-wire system has been actively carried out. For example, Japanese Patent Application Laid-Open No. 2004-151620 discloses a driving operation device for an automobile that employs a joystick as a steering handle. In this conventional operating device, the operating force of the joystick is proportional to the operating speed, and when the operating speed becomes higher than a certain level, a heavy and constant operating force is suddenly applied.

  As described above, the operation force applied to the joystick, in other words, the operation reaction force, has an elastic characteristic depending on the operation angle of the joystick and a viscosity characteristic proportional to the operation angular velocity. Finally, the operation reaction force calculated by multiplying the reaction force generated by the reaction force generating means according to the characteristic and the vehicle speed reaction force coefficient is applied to the joystick.

In the conventional operation device, the steering wheel (steered wheel) angle is calculated by multiplying the operation amount of the joystick by the steering gain. Here, the steering gain has a characteristic that varies depending on the vehicle speed.
JP 2000-313350 A

  By the way, in the conventional driving operation device for automobiles, the steering reaction force is always large in order to prevent the steered wheels (steered wheels) from being too large with respect to the operation amount of the joystick (so-called oversteer state). Is granted. In other words, the vehicle speed reaction force coefficient described above has a relationship that increases uniformly with respect to the steering gain. For example, when the steering gain is increased to reduce the operation amount of the joystick, the steering reaction gain is always increased. Power is granted. This places a physical burden on the driver and may impair the light operability.

  In addition, since the steering wheel (steered wheel) angle is calculated based on the steering gain that varies depending on the vehicle speed, for example, in a vehicle that travels in the middle speed range, the steering gain is large and the steering reaction force is large. From this state, when the vehicle shifts to a low speed range, the steering gain increases rapidly, while the steering reaction force decreases rapidly, and the operation characteristics change suddenly.

  The present invention has been made to solve the above-described problems, and an object of the present invention is to provide a vehicle steering apparatus that applies an optimal reaction force when necessary according to the operation state of the steering wheel by the driver. It is to provide.

  A feature of the present invention is that a steering handle operated by a driver to steer a vehicle, a reaction force actuator for applying a reaction torque to the operation of the steering handle, and the operation of the steering handle In a steering-by-wire vehicle steering apparatus, comprising: a steering actuator for steering the steered wheels; and a reaction force control device that controls driving of the reaction force actuator according to an operation of the steering handle. The reaction force control device determines that the operation input value detection means for detecting the operation input value of the driver for the steering handle and the turning operation of the steering handle in which the absolute value of the detected operation input value is increased are cut operations. A turning operation determining means for determining that the turning operation of the steering handle is a return operation, wherein the absolute value of the detected operation input value is small; A reaction force torque that has a predetermined relationship with a given operation input value, and a large reaction force torque is detected according to a turning operation state of the steering handle by a driver when it is determined that the cutting operation is performed. There is a configuration including reaction force torque calculation means for calculating based on the operation input value and calculating a small reaction force torque based on the detected operation input value when it is determined that the switchback operation is performed.

  In this case, the reaction force control device further compensates the phase of the detection signal representing the detected operation input value based on the determination of the cutting operation by the rotation operation determination unit, and performs phase compensation with the same phase compensation. Phase compensation means for outputting a detection signal, wherein the reaction force torque calculation means calculates a large reaction force torque during the cutting operation based on an operation input value after phase compensation represented by the phase compensation detection signal. Good. The phase compensation detection signal may be phase-compensated with a large gain with respect to the detection signal representing the detected operation input value.

  Furthermore, the reaction force torque calculation means is a torque that forms the reaction force torque based on the determination of the return operation by the rotation operation determination means, and the detected operation input value and a predetermined predetermined value. Of the viscous torque having a predetermined relation with the elastic torque having the relation and the time differential value of the detected operation input value, the value of the viscous torque may be calculated based on the predetermined relation. The predetermined relationship for calculating the value of the viscous torque to be small may be determined based on the time differential value of the detected operation input value.

  According to these, the reaction force torque calculation means can calculate a large reaction force torque according to the turning operation state of the steering handle when the steering handle is turned by the driver. This large reaction force torque can be calculated using a phase compensation detection signal that has been phase compensated so as to increase the gain with respect to the detection signal representing the detected operation input value. Thereby, in a normal rotation operation state, the gain difference between the detection signal and the phase compensation detection signal is small, so that a reaction torque having an appropriate magnitude can be applied.

  On the other hand, in the turning operation state in which the steering handle is turned quickly and greatly, the gain of the phase compensation detection signal is compensated so as to increase with respect to the gain of the detection signal. The torque can be calculated greatly. Thereby, according to the turning operation state of the steering handle by the driver, an appropriate reaction force can be applied when necessary. Therefore, it is possible to reduce the physical burden on the driver and to ensure light steering performance.

  Further, the reaction force torque calculation means can calculate the reaction force torque to be small when the steering wheel is turned back by the driver. In this case, in particular, the influence of the viscous torque acting depending on the steering angular velocity of the steering wheel can be suppressed by reducing the value of the viscous torque that forms the reaction torque. As a result, it is possible to prevent a sudden change in the reaction force torque, and for example, the steering handle can be easily turned back. Therefore, a good operation feeling can be ensured.

  Hereinafter, a vehicle steering apparatus according to an embodiment of the present invention will be described with reference to the drawings. FIG. 1 schematically shows a vehicle steering apparatus according to this embodiment.

  This steering device includes a steering handle 11 that is turned by a driver to steer left and right front wheels FW1 and FW2 as steered wheels. The steering handle 11 is fixed to the upper end of the steering input shaft 12, and the lower end of the steering input shaft 12 is connected to a reaction force actuator 13 including an electric motor and a speed reduction mechanism. As will be described later, the reaction force actuator 13 applies a predetermined reaction force according to the turning operation state of the driver's steering handle 11.

  In addition, the steering device includes a steering actuator 21 including an electric motor and a speed reduction mechanism. The turning force by the turning actuator 21 is transmitted to the left and right front wheels FW1 and FW2 via the turning output shaft 22, the pinion gear 23, and the rack bar 24. With this configuration, the rotational force from the steering actuator 21 is transmitted to the pinion gear 23 via the steering output shaft 22, and the rack bar 24 is displaced in the axial direction by the rotation of the pinion gear 23. Due to the displacement in the axial direction, the left and right front wheels FW1, FW2 are steered left and right.

  Next, an electric control device that controls the operation of the reaction force actuator 13 and the steering actuator 21 will be described. The electric control device includes a steering angle sensor 31, a steering torque sensor 32, a turning angle sensor 33, and a vehicle speed sensor 34.

  The steering angle sensor 31 is assembled to the steering input shaft 12, detects the rotation angle from the neutral position of the steering handle 11, and outputs the steering angle θ as an operation input value. The steering torque sensor 32 is also assembled with the steering input shaft 12, detects the torque input to the steering handle 11, and outputs it as torque T. The turning angle sensor 33 is assembled to the turning output shaft 22 to detect the turning angle from the neutral position of the turning output shaft 22 and corresponds to the actual turning angle δ (the turning angle of the left and right front wheels FW1, FW2). ). Here, regarding the steering angle θ and the actual turning angle δ, the neutral position is “0”, the left rotation angle is represented by a positive value, and the right rotation angle is represented by a negative value. The torque T represents a torque acting in the right direction as a positive value and a torque acting in the left direction as a negative value. The vehicle speed sensor 34 detects the vehicle speed of the vehicle and outputs it as the vehicle speed V.

  These sensors 31 to 34 are connected to the electronic control unit 35. The electronic control unit 35 includes a microcomputer including a CPU, a ROM, a RAM, and the like as main components. By executing various programs including a reaction force control program shown in FIG. Control each operation. Drive circuits 36 and 37 for driving the reaction force actuator 13 and the steering actuator 21 are connected to the output side of the electronic control unit 35, respectively. In the drive circuits 36 and 37, current detectors 36a and 37a for detecting a drive current flowing through the electric motor in the reaction force actuator 13 and the steering actuator 21 are provided. The drive current detected by the current detectors 36a and 37a is fed back to the electronic control unit 35 in order to control the drive of both electric motors.

  Next, the operation of the embodiment configured as described above will be described in detail. When an ignition switch (not shown) is turned on by the driver, the electronic control unit 35 (more specifically, the CPU) repeatedly executes the reaction force control program shown in FIG. 2 every predetermined short time.

  That is, the electronic control unit 35 starts execution of the reaction force control program in step S10, inputs the steering angle θ detected by the steering angle sensor 31 in step S11, and detects it by the vehicle speed sensor 34. Enter the vehicle speed V. Subsequently, in step S12, the electronic control unit 35 rotates the steering handle 11 by the driver based on the detected steering angle θ input in step S11, and the absolute value of the detected steering angle θ increases. It is determined whether a rotation operation (hereinafter, this rotation operation is referred to as a cutting operation) or a rotation operation (hereinafter, this rotation operation is referred to as a return operation) in which the absolute value of the detected steering angle θ is reduced. To do. Hereinafter, this determination will be described.

  Considering the case where the steering handle 11 is turned rightward, the detected steering angle θ output from the steering angle sensor 31 is a negative value. In this state, when the steering handle 11 is turned, the electronic control unit 35 has a time differential value dθ / dt of the detected steering angle θ (hereinafter, this differential value is referred to as a steering angular velocity dθ / dt) negative. If the value is a value, it is determined that the driver has performed the cutting operation, and if the steering angular velocity dθ / dt is a positive value, it is determined that the driver has performed the switching operation.

  On the other hand, when the case where the steering handle 11 is rotated to the left is considered, the detected steering angle θ output from the steering angle sensor 31 is a positive value. In this state, when the steering handle 11 is rotated, the electronic control unit 35 determines that the driver has made a cutting operation if the steering angular velocity dθ / dt is a positive value, and the steering angular velocity dθ / dt. If is a negative value, it is determined that the driver has performed a switchback operation.

  Here, in determining the cutting operation and the reversing operation, as described later, in order to switch and execute the reaction force control contents according to the determined cutting operation or reverting operation, between the cutting operation and the reverting operation. A dead zone is provided. That is, if the electronic control unit 35 determines these operations at the same time that the driver performs a cutting operation or a switching back operation, for example, the driver turns the steering handle 11 in the left-right direction for fine adjustment. Even in this case, the reaction force control content is changed each time. As described above, frequent switching of the control contents causes a problem that, for example, the reaction force perceived by the driver via the steering wheel 11 varies greatly.

  On the other hand, by providing a dead zone regarding the determination of the cutting operation and the switching back operation, it is possible to prevent the electronic control unit 35 from frequently determining the cutting operation or the switching back operation due to the fine adjustment of the driver. The above problem is solved. Here, as the dead zone, for example, a determination time until determining a cutting operation and a switching back operation can be employed. Thereby, in the turning operation of the steering handle 11, the uncomfortable feeling that the driver learns can be reduced.

  In the determination process of step S12, if the steering handle 11 is currently turned by the driver, the electronic control unit 35 determines “Yes” and proceeds to step S13. In step S <b> 13, the electronic control unit 35 calculates a basic reaction force torque map for determining a target reaction force torque Tfa to be described later to be given to the turning operation of the steering handle 11 by the driver. Hereinafter, the calculation of this map will be described in detail.

  In the steering-by-wire type steering apparatus, with respect to the turning operation of the steering handle 11, a spring term component that is mainly determined according to the steering angle θ and a viscosity term component that is determined according to the steering angular velocity dθ / dt. Are applied as reaction force torque. Here, as shown in FIG. 3, the spring term component term is determined as, for example, an elastic torque Mte proportional to the steering angle θ. As shown in FIG. 4, the viscosity term component is determined as, for example, a viscous torque Mtd that is proportional to the steering angular velocity dθ / dt.

  The magnitudes of the elastic torque Mte and the viscous torque Mtd change according to the vehicle speed range of the vehicle, for example. That is, the elastic torque Mte and the viscous torque Mtd have large values so that an appropriate reaction torque is applied to the steering handle 11 in the high speed range, and the steering handle 11 can be easily rotated in the low speed range. It becomes a small value. For this reason, the electronic control unit 35 calculates a corresponding basic reaction force torque map based on the detected vehicle speed V input in step S11.

  After the map calculation process in step S13, the electronic control unit 35 executes a phase compensation filter process in step S14. Hereinafter, the phase compensation filter process will be specifically described.

  As described above, the steering-by-wire steering device includes the steering input shaft 12 and the steering output shaft 22, and the steering input shaft 12 is connected to the steering handle 11 and the reaction force actuator 13, and the steering output is provided. The shaft 22 is connected to the steering actuator 21 and the left and right front wheels FW1, FW2. In other words, the mechanical connection between the steering handle 11 and the left and right front wheels FW1, FW2 is removed. Therefore, the ratio of the steering angle δ to the steering angle θ, that is, the steering gain can be set freely. Thus, for example, if the steering gain is set large, a large turning angle δ can be obtained with a small steering angle θ, so that the driver can turn the vehicle very easily without changing the steering handle 11. it can.

  However, a driver who has long experience of operating a conventional steering device other than the steering-by-wire system may feel uncomfortable with the turning behavior of the vehicle until he / she gets used to the steering gain characteristic described above. That is, in a steering-by-wire type steering device having a large steering gain, the steering handle 11 is not quickly and greatly rotated (hereinafter, this rotational operation is referred to as a fast rotational operation) unlike the conventional steering device. However, despite the fact that the vehicle can be turned significantly, the driver may perform a quick turning operation based on past operation experience. As a result, the left and right front wheels FW1, FW2 become larger than the steering angle δ expected by the driver (so-called oversteer state), and steering for correcting the turning behavior of the vehicle (hereinafter referred to as correction steering) is required. However, it may be difficult to drive.

  By the way, when a fast turning operation is performed, a large phase advance occurs in a signal (hereinafter referred to as a detection signal) representing the steering angle θ output from the steering angle sensor 31. For this reason, the electronic control unit 35 performs phase compensation on the detection signal by filtering the detection signal using a phase compensation filter. Then, the electronic control unit 35 calculates a target reaction force torque Tfa described later using this phase compensated detection signal. Here, the phase compensation characteristic of the phase compensation filter is experimentally determined based on the peak frequency at which the maximum phase advance value for phase compensation appears and the gain at this peak frequency.

  In other words, the electronic control unit 35 uses the phase compensation filter to perform phase advance filtering on the detection signal to compensate for the phase advance of the detection signal. As described above, the detection signal whose phase advance is compensated (hereinafter referred to as a phase compensation detection signal) changes the gain with respect to the detection signal in accordance with the phase advance of the detection signal output from the steering angle sensor 31. More specifically, the faster the turning operation is performed by the driver, the larger the phase advance of the detection signal, and the greater the gain of the phase compensation detection signal with respect to the detection signal. When the detection signal is filtered and phase compensated, the electronic control unit 35 proceeds to step S15.

  In step S15, the electronic control unit 35 calculates the target reaction force torque Tfa based on the phase compensation detection signal filtered in step S14. That is, the electronic control unit 35 calculates the target reaction force torque Tfa according to the basic reaction force torque map calculated in step S13, using the phase compensated steering angle θa represented by the phase compensation detection signal.

  Specifically, the electronic control unit 35 calculates the elastic torque Mte as a spring component term based on the map of FIG. 3 using the steering angle θa. Further, the electronic control unit 35 uses the steering angular velocity dθa / dt calculated for the steering angle θa to calculate the viscous torque Mtd as a viscous component term based on the map of FIG. Then, the electronic control unit 35 adds the calculated elastic torque Mte and the viscous torque Mtd to calculate the target reaction force torque Tfa.

  Incidentally, as described above, the gain of the phase compensation detection signal representing the phase-compensated steering angle θa is changed with respect to the detection signal representing the detected steering angle θ input from the steering angle sensor 31 by the filtering process in step S13. The In particular, when the driver performs a fast turning operation, the gain of the phase compensation detection signal increases. Therefore, when a fast turning operation is performed, the steering angle θa represented by the phase compensation detection signal becomes a larger value than the detected steering angle θ.

  For this reason, the elastic torque Mte and the viscous torque Mtd calculated using the steering angle θa based on the maps of FIGS. 3 and 4, that is, the target reaction force torque Tfa, is a normal rotation with a small (slow) phase advance. It is calculated to be larger than when the operation is performed. As a result, when the driver performs a quick turning operation, a larger target reaction torque Tfa is applied to the steering handle 11, so that the driver can perform the turning operation of the steering handle 11. Appropriate resistance is perceived. And the electronic control unit 35 will progress to step S20, if the target reaction force torque Tfa is calculated.

  In step S12, if the steering handle 11 has not been turned, in other words, if the steering handle 11 has been turned back, the electronic control unit 35 determines “No” and proceeds to step S16.

  Each process after step S16 is reaction force control when the steering wheel 11 is turned back by the driver. Here, in the steering-by-wire type steering apparatus, as described above, the elastic torque Mte and the viscous torque Mtd are mainly applied to the steering handle 11. That is, in the steering-by-wire type steering device, the mechanical connection between the steering handle 11 and the left and right front wheels FW1 and FW2 is disengaged. It is not applied to the steering wheel 11 as a reaction force.

  For this reason, in a steering-by-wire type steering apparatus, for example, the torque required for the driver to maintain the current turning operation position of the steering handle 11 (that is, the steering torque) is reduced, and the steering handle 11 is moved to the neutral position. Even when trying to return naturally to the direction, the steering handle 11 may not fully return to the neutral position direction.

  More specifically, in the steering handle 11 that is turned back, the viscous torque Mtd that forms the basic reaction force torque is generated depending on the steering angular velocity dθ / dt in the turning back direction of the steering handle 11, and steering is performed. It always acts to resist the rotation of the handle 11. In the steering-by-wire type steering apparatus, since the self-alignment torque is not input, the torque for rotating the steering handle 11 toward the neutral position is the elastic torque Mte that forms the basic reaction torque. For this reason, depending on the magnitude relationship between the viscous torque Mtd and the elastic torque Mte, the steering handle 11 may be prevented from turning in the neutral position direction. Therefore, in order to ensure the natural return characteristic toward the neutral position of the steering handle 11 during the return operation, it is necessary to reduce the viscous torque Mtd that forms the basic reaction torque.

  For this reason, in step S16, the electronic control unit 35 calculates the steering angular velocity dθ / dt of the absolute value of the detected steering angle θ input in step S11, and is well known for this steering angular velocity dθ / dt. Based on the method, ± 1 limiter processing is performed. Then, the electronic control unit 35 sets the value after the limiter process as a variable B, and proceeds to step S17.

In step S17, the electronic control unit 35 uses the variable B set in step S16 to calculate a coefficient β for decreasing the viscous torque Mtd according to the following equation 1.
β = (B + 1) / 2 Equation 1
However, the coefficient β is a coefficient having a value of 0 <β <1.

  After the calculation process of step S17, the electronic control unit 35 performs a map calculation of the viscous torque Mtd in step S18. That is, the electronic control unit 35 calculates the viscous torque Mtd at the current steering angular velocity dθ / dt using the characteristic map of the viscous torque Mtd shown in FIG. The viscosity torque Mtd calculated in this way acts as a resistance torque that suppresses the rotation of the steering handle 11, whereas the elastic torque Mte acts as a torque that rotates the steering handle 11 in the neutral position direction.

Therefore, the electronic control unit 35 executes a correction calculation of the viscous torque Mtd in step S19 in order to reduce the viscous torque Mtd calculated in the map in step S18. That is, the electronic control unit 35 calculates the corrected viscous torque Mtdh corrected so that the viscous torque Mtd is reduced according to the following equation 2 using the coefficient β calculated in step S17.
Mtdh = β · Mtd… Formula 2
As a result, the electronic control unit 35 adds the corrected viscous torque Mtdh calculated according to the above equation 2 and the elastic torque Mte calculated in proportion to the detected steering angle θ, so that the target reaction force during the switchback operation is obtained. Calculate torque Tfb. When the electronic control unit 35 calculates the corrected viscous torque Mtdh and calculates the target reaction force torque Tfb, the electronic control unit 35 proceeds to step S20.

  In step S20, the electronic control unit 35 controls the operation of the reaction force actuator 13, and steers the target reaction force torque Tfa calculated in step S15 or the target reaction force torque Tfb calculated in step S19. This is applied to the steering handle 11 via the input shaft 12. More specifically, the electronic control unit 35 inputs a drive current flowing from the drive circuit 36 to the electric motor in the reaction force actuator 13 and also receives a torque T from the steering torque sensor 32, and outputs the target reaction to the electric motor. The drive circuit 36 is feedback-controlled so that a drive current corresponding to the force torque Tfa or the target reaction force torque Tfb flows. By the drive control of the electric motor in the reaction force actuator 13, the electric motor applies a reaction force corresponding to the target reaction force torque Tfa or the target reaction force torque Tfb to the steering handle 11 via the steering input shaft 12. .

  In this way, the driver perceives an appropriate reaction force via the steering handle 11 by controlling the reaction force actuator 13 to be operated. More specifically, when the driver is turning the steering handle 11, if the driver is performing a normal turning operation, the driver can set the target reaction force torque Tfa determined using the detected steering angle θ. While perceiving, the vehicle can be turned with the turning behavior expected very easily.

  In addition, in the case of a cutting operation, if it is a fast turning operation, the driver will perceive a larger target reaction force torque Tfa than in a normal turning operation, in other words, a sense of resistance, As a result, a fast turning operation is suppressed. This prevents the steering handle 11 from being turned too much, so that the turning angle δ of the left and right front wheels FW1, FW2 is prevented from becoming too large. Therefore, the driver can turn the vehicle with the expected turning behavior.

  On the other hand, when the driver is turning back the steering handle 11, the driver can turn the steering handle 11 toward the neutral position very easily while perceiving the target reaction force torque Tfb calculated to be small. Can be operated. Thereby, for example, in the case of corrective steering according to the turning behavior of the vehicle, the steering handle 11 can be quickly rotated, and the turning angle δ of the left and right front wheels FW1, FW2 can be corrected quickly. it can. Further, for example, when the driver reduces the steering torque and naturally returns the steering handle 11 toward the neutral position, a small corrected viscous torque Mtdh acts on the elastic torque Mte. Return to the neutral position.

  Here, when the steering handle 11 is turned by the driver and the steering angle θ is input, the electronic control unit 35 calculates the turning angle δ corresponding to the input steering angle θ. . Then, the left and right front wheels FW1, FW2 are steered so as to coincide with the steered angle δ. That is, the electronic control unit 35 inputs the drive current flowing from the drive circuit 37 to the electric motor in the turning actuator 21 and the actual turning angle detected by the turning angle sensor 33. Then, the electronic control unit 35 feedback-controls the drive circuit 37 so that an appropriate drive current flows through the electric motor in the steered actuator 21 so that the left and right front wheels FW1, FW2 are steered to the steered angle δ.

  By the drive control of the electric motor in the steering actuator 21, the rotation of the electric motor is transmitted to the pinion gear 23 via the steering output shaft 22, and the rack bar 24 is displaced in the axial direction by the pinion gear 23. Due to the displacement of the rack bar 24 in the axial direction, the left and right front wheels FW1, FW2 are steered to a turning angle δ corresponding to the steering angle θ.

  As can be understood from the above description, according to this embodiment, when the steering handle 11 is turned, a large target reaction force torque Tfa can be calculated according to the turning operation state of the steering handle 11. . This large target reaction force torque Tfa can be calculated using a phase compensation detection signal (steering angle θa) that is phase-compensated so that the gain with respect to the detection signal representing the steering angle θ detected by the steering angle sensor 31 is increased. it can. As a result, in a normal turning operation state, the gain difference between the detection signal and the phase compensation detection signal is small, so that an appropriate magnitude of the target reaction force torque Tfa can be calculated, and an appropriate magnitude of the reaction force is steered. It can be applied to the handle 11.

  On the other hand, in a fast turning operation state in which the steering handle 11 is turned quickly and largely, compensation is made so that the gain of the phase compensation detection signal becomes larger than the gain of the detection signal. For this reason, a larger target reaction torque Tfa can be greatly calculated in a fast turning operation state. In this manner, an appropriate target reaction force torque Tfa can be calculated when necessary according to the turning operation state of the steering handle 11 by the driver, and an optimum reaction force can be applied. Therefore, it is possible to reduce the physical burden on the driver and to ensure light steering performance.

  Further, when the steering wheel 11 is turned back by the driver, a small target reaction torque Tfb can be calculated. In this case, in particular, the influence of the viscous torque Mtd acting depending on the steering angular velocity dθ / dt of the steering handle 11 is suppressed by calculating by reducing the value of the viscous torque Mtd forming the basic reaction torque. Can do. As a result, it is possible to prevent a sudden change in the reaction force torque, and for example, the steering handle 11 can be easily turned back. Therefore, a good operation feeling can be ensured.

  In carrying out the present invention, the present invention is not limited to the above embodiment, and various modifications can be made without departing from the object of the present invention.

  For example, in the above embodiment, the steering handle 11 that is turned to steer the vehicle is used. However, instead of this, for example, a joystick-type steering handle that is linearly displaced may be used, or any other one that can be operated by the driver and instructed to steer the vehicle is used. May be.

  In the above embodiment, the left and right front wheels FW1, FW2 are steered by rotating the steered output shaft 22 using the steered actuator 21. However, instead of this, the left and right front wheels FW1, FW2 may be steered by linearly displacing the rack bar 24 using the steered actuator 21.

1 is a schematic view of a vehicle steering apparatus according to an embodiment of the present invention. It is a flowchart showing the reaction force control program performed with the electronic control unit of FIG. It is a graph which shows the relationship between a steering angle and elastic torque. It is a graph which shows the relationship between steering angular velocity and viscous torque.

Explanation of symbols

FW1, FW2 ... front wheel, 11 ... steering handle, 12 ... steering input shaft, 13 ... reaction actuator, 21 ... steering actuator, 22 ... steering output shaft, 31 ... steering angle sensor, 32 ... steering torque sensor, 33 ... Steering angle sensor 34 ... Vehicle speed sensor 35 ... Electronic control unit

Claims (5)

A steering handle operated by a driver to steer the vehicle, a reaction force actuator for applying a reaction torque to the operation of the steering handle, and steered wheels according to the operation of the steering handle A steering-by-wire vehicle steering apparatus comprising: a steering actuator for controlling the driving force; and a reaction force control device that controls driving of the reaction force actuator in accordance with an operation of the steering handle.
An operation input value detecting means for detecting an operation input value of a driver for the steering wheel;
The turning operation of the steering handle in which the absolute value of the detected operation input value is increased is determined as a cutting operation, and the turning operation of the steering handle in which the absolute value of the detected operation input value is decreased is a return operation. A rotation operation determining means for determining;
A reaction force torque having a predetermined relationship with the detected operation input value, and a large reaction force torque is detected according to a turning operation state of the steering handle by the driver when it is determined that the cutting operation is performed. And a reaction force torque calculating means for calculating a small reaction force torque based on the detected operation input value when it is determined that the switch back operation is performed. Steering-by-wire vehicle steering system. The steering apparatus for a steering-by-wire vehicle according to claim 1,
The reaction force control device further includes:
Based on the determination of the cutting operation by the rotation operation determination means, phase compensation for the detection signal representing the detected operation input value, phase compensation means for outputting a phase compensation detection signal compensated in phase,
Steering-by-wire vehicle characterized in that the reaction torque calculation means calculates a large reaction torque during the cutting operation based on an operation input value after phase compensation represented by the phase compensation detection signal. Steering device. In the steering device for a steering-by-wire vehicle according to claim 2,
The phase compensation detection signal is phase-compensated with a large gain with respect to the detection signal representing the detected operation input value. The steering apparatus for a steering-by-wire vehicle according to claim 1,
The reaction torque calculation means includes
Based on the determination of the return operation by the rotation operation determination means,
Viscosity that forms the reaction torque and has a predetermined predetermined relationship with an elastic torque having a predetermined relationship with the detected operation input value and a time differential value of the detected operation input value. A steering-by-wire steering apparatus for a vehicle, wherein the value of the viscous torque among the torques is calculated to be small based on a predetermined relationship. In the steering device for a steering-by-wire vehicle according to claim 4,
The predetermined relationship for calculating the value of the viscous torque to be small is:
A steering-by-wire steering apparatus for a vehicle, which is determined based on a time differential value of the detected operation input value.

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