JP2009274609A - Reaction control device and reaction setting method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a reaction control device and a reaction setting method for applying reaction torque with an optimum variation depending on the operation state of a steering wheel operated by a driver. <P>SOLUTION: An electronic control unit 35 determines whether the steering wheel 11 is inversely operated, i.e., whether the steering wheel 11 is vibrating or not based on a sign obtained by multiplying a previous difference value Δθ<SB>n-1</SB>by a present difference value Δθ<SB>n</SB>. The electronic control unit computes a small value of a gain α when the steering wheel 11 vibrates, and computes a large value of the gain α when the steering wheel 11 does not vibrate due to a non-inverting operation. Thus, the electronic control unit 35 computes a new difference value Δθ<SB>n_new</SB>by multiplying the gain α by the difference value Δθ<SB>n</SB>, and computes a variation ΔTf of friction torque Tf using the difference value Δθ<SB>n_new</SB>. The friction torque Tf is then computed by adding the computed variation ΔTf to the previous friction torque Tf<SB>n-1</SB>. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention is applied to a vehicle including a steering handle operated by a driver and a reaction force generation device for generating and applying a reaction force torque to the operation of the steering handle. The reaction force control device for setting and controlling the reaction force torque applied by the reaction force generator according to the operation state, and the reaction force torque applied to the operation of the steering wheel of the vehicle by the driver are changed to the operation state of the steering wheel. The present invention relates to a reaction force setting method to be set accordingly.

  Conventionally, for example, a steering device and a steering reaction force setting method disclosed in Patent Document 1 below are known. In this conventional apparatus and method, it is determined whether or not the steering wheel is turned back and forth based on the detected steering angle of the steering wheel, and the target steering reaction force is determined with hysteresis characteristics based on the determination result and the detected steering angle. Is set. Thereby, the steering reaction force at the time of steering can be stabilized.

Conventionally, for example, a vehicle steering apparatus disclosed in Patent Document 2 below is also known. In this conventional vehicle steering apparatus, the friction torque and the viscous torque corresponding to the steering angular velocity are calculated, and the target reaction force torque is calculated by adding the friction torque and the viscous torque to the spring term component torque. It has become. As a result, the jerky feeling associated with minute vibrations of the steering wheel can be eliminated, and a smoothly changing target reaction force torque can be applied.
Japanese Patent No. 3889916 JP 2007-137287 A

  By the way, in general, the driver has a tendency to hold the steering wheel (handle) while causing a minute angular deflection. In this case, just by determining the target steering reaction force and the target reaction force torque based on the change in the operation state of the steering handle by the driver, that is, the change in the steering angle and the steering angular velocity, as in the conventional devices described above, for example, Due to the difference in the detection resolution of the steering angle and the steering angular velocity, fluctuations in the reaction force (reaction torque) associated with a minute angular swing of the steering handle may be perceived and the steering feeling may be deteriorated.

  In other words, if the detection resolution of the steering angle and the steering angular velocity is high (fine), the fluctuation range of the target reaction force (reaction torque) at each sampling time is small and cannot be perceived by the driver. However, there is a low possibility that the steering feeling will deteriorate. However, when the detection resolution of the steering angle and steering angular velocity is low (coarse), the fluctuation range of the target reaction force (reaction force torque) also increases, so that the driver can change the reaction force (reaction force torque). Perceived, it is considered that there is a high possibility that the steering feeling will deteriorate.

  The present invention has been made in order to solve the above-described problems, and an object of the present invention is to provide a reaction force control device capable of applying a reaction force torque having an optimum amount of fluctuation according to an operation state of a steering wheel by a driver, and It is to provide a reaction force setting method.

  A feature of the present invention is applied to a vehicle including a steering handle operated by a driver, and a reaction force generation device for generating and applying a reaction force torque to the operation of the steering handle. In a reaction force control device that sets and controls a reaction force torque applied by the reaction force generator according to an operation state of a steering wheel, a driver's operation input value for the steering wheel is detected at every predetermined sampling time. Steering wheel vibration generation determination for determining whether or not vibration is generated in the operation direction of the steering wheel using an operation input value detection unit and a past history of the operation input value detected by the operation input value detection unit And when the vibration is generated in the steering handle by the steering handle vibration generation determining means The amount of fluctuation between the reaction force torques corresponding to the operation input value is uniformly reduced to a preset lower limit value, and vibration is generated in the steering wheel by the steering wheel vibration generation determination means. If not, use the reaction force torque fluctuation amount changing means for uniformly increasing the fluctuation amount to a preset upper limit value and changing the fluctuation amount changed by the reaction force torque fluctuation amount changing means. And a target reaction torque setting means for setting a target reaction torque generated and applied by the reaction force generator.

  In this case, the steering handle vibration occurrence determination means uses the past history of the difference value between each operation input value detected at every predetermined sampling time by the operation input value detection means. The sign of the current difference value corresponding to the operation input value detected at the current sampling time and the sign of the past difference value corresponding to the operation input value detected at the past sampling time a predetermined number of times It is determined that vibrations in the operation direction of the steering wheel occur when they are different, and vibrations in the operation direction of the steering wheel are detected when the sign of the current difference value and the sign of the past difference value are all the same. It is good to determine that it has stopped.

  Also, in these cases, the reaction torque fluctuation amount changing means changes the steering wheel vibration generation determining means to the fluctuation amount proportional to the operation input value detected by the operation input value detecting means. Each time it is determined that vibration in the operation direction of the steering wheel is generated, and it is uniformly reduced, and whenever it is determined that vibration in the operation direction of the steering wheel is stopped, The gain value that increases uniformly may be changed using a new operation input value obtained by multiplying the operation input value detected at predetermined sampling times by the operation input value detection means.

  Further, the reaction torque fluctuation amount changing means uses a friction torque coefficient value representing a slope in the proportional relationship, with the fluctuation amount being proportional to the operation input value detected by the operation input value detecting means. Thus, every time it is determined that vibration in the operation direction of the steering wheel is generated based on the determination by the steering wheel vibration generation determination means, the friction torque coefficient value is reduced uniformly, and the steering wheel operation Each time it is determined that the vibration in the direction is stopped, the friction torque coefficient value is preferably increased by increasing it uniformly.

  According to another aspect of the present invention, there is provided a reaction force setting method for setting a reaction force torque applied to an operation of a steering handle of a vehicle by a driver according to an operation state of the steering handle. A user's operation input value is detected at every predetermined sampling time, and it is determined whether vibration in the operation direction of the steering wheel is generated using a past history of the detected operation input value, and the steering When vibration is generated in the handle, the amount of fluctuation between the reaction force torques corresponding to the operation input value detected at each predetermined sampling time is uniformly set to a preset lower limit value. When the vibration is not generated in the steering wheel, the variation amount is uniformly increased to a preset upper limit value, and the variation amount is changed. There are also to have to set the target reaction force torque applied to the operation of the steering wheel.

  In this case, using the past history of the difference value between the operation input values detected at each predetermined sampling time, the sign of the current difference value corresponding to the operation input value detected at the current sampling time and When the sign of the past difference value corresponding to the operation input value detected at a past sampling time only a predetermined number of times is different from one another, it is determined that vibration in the operation direction of the steering wheel has occurred, It is preferable to determine that the vibration in the operation direction of the steering wheel is stopped when the sign of the difference value is the same as the sign of the past difference value.

  In these cases, the fluctuation amount is proportional to the detected operation input value, and the fluctuation amount is determined every time it is determined that vibration in the operation direction of the steering wheel is generated. The operation input value detected at each predetermined sampling time is multiplied by a gain value that decreases in a similar manner and increases uniformly every time it is determined that the vibration in the operation direction of the steering wheel is stopped. It is good to change using the new operation input value.

  Further, the fluctuation amount is proportional to the detected operation input value, and the fluctuation amount is determined by using a friction torque coefficient value representing an inclination in the proportional relationship, and vibration in the operation direction of the steering wheel. Each time it is determined that the friction torque coefficient is generated, the friction torque coefficient value is uniformly decreased, and every time it is determined that vibration in the operation direction of the steering wheel is stopped, the friction torque coefficient value is increased uniformly. It is better to change it depending on the situation.

  According to these, when vibration is generated in the steering wheel, each reaction force torque (more specifically, the reaction torque) applied (determined) corresponding to the operation input value detected at every predetermined sampling time. The amount of variation between the friction torques forming the force torque) can be uniformly reduced to a preset lower limit value. On the other hand, when no vibration is generated in the steering wheel, the amount of variation between the reaction force torques (friction torques) can be uniformly increased to a preset upper limit value.

  As a result, for example, even in a situation where the driver keeps the steering wheel so as to cause a minute angular shake (vibration), the fluctuation amount of the reaction force torque (friction torque) that fluctuates with the vibration is reduced to the lower limit. Can be made smaller. For this reason, even if the reaction force torque (friction torque) actually fluctuates, it can be made difficult to be perceived by the driver, and a good steering feeling can be ensured. On the other hand, for example, when the driver is operating the steering wheel in one direction, in other words, when the steering wheel is not vibrating, the variation amount of the reaction torque (friction torque) is increased to the upper limit. Can do. For this reason, the driver can perceive an appropriate reaction force according to the operation of the steering wheel, and can ensure a good steering feeling.

  As for determining whether or not vibration is generated in the steering wheel, the sign of the current difference value corresponding to the operation input value detected at the current sampling time and a predetermined number of times are detected at the past sampling time. Based on the sign of the past difference value corresponding to the operated input value, it can be determined that vibration in the steering direction of the steering wheel is occurring when any of these signs are different. Further, it can be determined that the vibration in the operation direction of the steering wheel is stopped when the sign of the current difference value and the sign of the past difference value are all the same. Thereby, it is not necessary to perform complicated determination processing, and it is possible to determine whether vibration is generated in the steering wheel very easily and accurately.

  Further, when the variation amount between the reaction force torques (friction torques) applied corresponding to the operation input value detected at each predetermined sampling time is proportional to the detected operation input value The amount of variation in the reaction torque (friction torque) is uniformly reduced every time it is determined that vibration in the steering handle operating direction is generated, and the vibration in the steering handle operating direction is stopped. The gain value that increases uniformly every time it is determined can be changed using a new operation input value obtained by multiplying the operation input value detected at each predetermined sampling time. Further, using the friction torque coefficient value representing the slope in the proportional relationship, the friction torque coefficient value is uniformly lowered every time it is determined that vibrations in the steering handle operating direction occur, Each time it is determined that the vibration is stopped, it can be changed by uniformly increasing the friction torque coefficient value.

  Thereby, the fluctuation amount of the reaction force torque (friction torque) can be reliably changed according to the operation state of the steering wheel. Therefore, even in a situation where vibration is generated in the steering wheel, it is possible to make it difficult for the driver to perceive the fluctuation of the reaction torque (friction torque), and to ensure a good steering feeling. . On the other hand, in a situation where vibration is not generated in the steering wheel, the driver can perceive a reaction force according to the operation of the steering wheel, and can secure a good steering feeling.

a. First Embodiment Hereinafter, a reaction force control device according to a first embodiment of the present invention will be described with reference to the drawings. FIG. 1 schematically shows a steer-by-wire steering device provided with a reaction force control device according to the present invention in common with each 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 as a reaction force generating device 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.

  A steering angle sensor 31 as an operation input value detecting means is assembled to the steering input shaft 12 to detect a rotation angle from the neutral position of the steering handle 11 at every predetermined sampling time, and to steer as an operation input value. Output θ. 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. 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 31-34 are connected to the electronic control unit 35 which comprises a reaction force control apparatus. 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 first embodiment of the steering apparatus 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. Here, the electronic control unit 35 stores the input steering angle θ in the order of input, for example, as a past history in a predetermined storage position of the RAM. Subsequently, in step S12, the electronic control unit 35 calculates a basic reaction force torque Tb to be applied to the turning operation of the steering handle 11 by the driver. Hereinafter, the calculation of the basic reaction force torque Tb will be specifically described.

  In the steer-by-wire steering device, a component that generates an elastic force in proportion to the steering angle θ according to the steering angle θ that changes with the turning operation of the steering handle 11 (so-called spring term component). The basic reaction force torque Tb is mainly applied. This basic reaction force torque Tb changes according to the speed range of the vehicle, for example. That is, the basic reaction force torque Tb has a large value so that an appropriate reaction force is applied to the steering handle 11 in the high speed range, and a small value so that the steering handle 11 can be easily rotated in the low speed range. It becomes.

  Therefore, the electronic control unit 35 first determines a basic reaction force torque map (not shown) based on the detected vehicle speed V input in step S11. Then, the electronic control unit 35 calculates a basic reaction force torque Tb corresponding to the detected steering angle θ input in step S11, using the determined basic reaction force torque map. As described above, when the basic reaction force torque Tb is calculated, the electronic control unit 35 proceeds to step S13.

  In step S13, the electronic control unit 35 executes a frictional vibration reduction calculation routine. Hereinafter, this routine will be described in detail.

  In the steering device employing the steer-by-wire system, as described above, the mechanical connection between the steering handle 11 and the left and right front wheels FW1, FW2 is released. That is, when the driver rotates the steering handle 11, only the reaction force generated by the reaction force actuator 13 is applied. In this case, in a situation where only the basic reaction force torque Tb is applied, an elastic force is mainly applied to the turning operation of the steering handle 11 by the driver.

  By the way, when the driver keeps the vehicle in a turning state, the steering handle 11 needs to be held in a state in which the steering handle 11 is rotated to a certain steering angle θ, that is, the steering handle 11 needs to be steered. However, in this case, the driver must always hold the steering handle 11 by inputting a steering force against the reaction force (basic reaction force torque Tb). On the other hand, when the vehicle is maintained in the straight traveling state, the steering handle 11 needs to be held at the neutral position. However, in this case, since the steering angle θ is maintained in the vicinity of “0”, the applied reaction force (basic reaction force torque Tb) is extremely small, and the driver needs to hold the steering handle 11 firmly. There is.

  In order to reduce such a physical burden on the driver, in a steering device adopting a steer-by-wire method, in general, in a normal steering device that does not employ a steer-by-wire method, A feeling of friction (friction torque) that is inevitably generated in terms of structure is artificially generated and applied. However, in a situation where pseudo friction torque is applied, for example, when the driver is turning the steering handle 11 slightly in the left-right direction near the neutral position when the vehicle is traveling straight, or when the vehicle is turning, the steering handle 11 is turned on. When the steering operation is performed, there is a possibility that the application direction of the friction torque is repeatedly reversed to generate a so-called friction vibration.

  When such frictional vibration occurs, if the variation amount of the friction torque with respect to the turning operation of the steering handle 11 is small, it is difficult for the driver to perceive the variation accompanying the reversal of the friction torque and to feel uncomfortable. On the other hand, if the fluctuation amount of the friction torque with respect to the turning operation of the steering handle 11 is large, it is easy for the driver to perceive the fluctuation accompanying the reversal of the friction torque, and feels strange. In a state where the driver feels such a sense of incongruity, a good steering feeling cannot be obtained.

  Based on this, the electronic control unit 35 executes the frictional vibration reduction calculation routine shown in FIG. 3 so as to suppress the uncomfortable feeling that the driver learns due to the change in the friction torque, so that a good steering feeling can be obtained. To. That is, the electronic control unit 35 starts execution of the friction vibration reduction calculation routine in step S50. In step S51, the electronic control unit 35 calculates the variation amount ΔTf of the friction torque Tf calculated and applied as described later. The change suppression constants A and B for changing according to the dynamic operation state are calculated. Specifically, the electronic control unit 35 calculates change suppression constants A and B (both positive values) according to the magnitude of the basic reaction force torque Tb calculated in step S12.

  More specifically, the electronic control unit 35 is an upper limit value in which the magnitudes of the change suppression constants A and B are constant when the basic reaction force torque Tb is small relative to the magnitude (absolute value) of the basic reaction force torque Tb. Thus, when the basic reaction force torque Tb is large, the magnitudes of the change suppression constants A and B become a certain lower limit, and the magnitudes of the change suppression constants A and B increase with a decrease (increase) in the basic reaction force torque Tb. The map shown in FIG. 4A is used which represents a change characteristic that uniformly changes from the upper limit value to the lower limit value (lower limit value to upper limit value). Then, the electronic control unit 35 performs map calculation of the change suppression constants A and B corresponding to the basic reaction force torque Tb calculated in step S12. As described above, when the change suppression constants A and B are calculated, the electronic control unit 35 proceeds to step S52.

  In the first embodiment, the map shown in FIG. 4A is used to calculate the change suppression constants A and B as the same value based on the absolute value of the basic reaction force torque Tb. However, the change suppression constants A and B may be calculated as different values, or the change suppression constants A and B may be calculated using different maps, as illustrated in FIG. 4B. Is possible.

In step S52, the electronic control unit 35 inputs and stores the steering angle θ _n−2 (hereinafter referred to as the previous steering angle θ _n−2 ) input and stored when the previous reaction force control program is executed, and the previous reaction force control program. It is determined whether or not the steering angle θ _n-1 (hereinafter referred to as the previous steering angle θ _n-1 ) input and stored at the time of execution is different. That is, the electronic control unit 35 has a difference between the previous steering angle θ _n-1 and the previous steering angle θ _n-2 at the time of execution of the previous reaction force control program, in other words, at the time of execution of the previous reaction force control program. If the steering handle 11 has been slightly rotated by the driver, the determination is “Yes” and the process proceeds to step S53. On the other hand, when the previous reaction force control program is executed, the previous steering angle θ _n-1 and the previous steering angle θ _n-2 are the same, in other words, the steering handle 11 by the driver at the time of execution of the previous reaction force control program. If is not finely rotated, the electronic control unit 35 determines “No” and proceeds to step S54. That is, in this case, no frictional vibration has occurred in the steering handle 11 during the previous execution of the reaction force control program.

In step S53, the electronic control unit 35 follows the following expression 1 to obtain a difference value Δθ _n-1 between the previous steering angle θ _n-1 and the previous steering angle θ _n-2 (hereinafter referred to as the previous difference value Δθ _n-1 ). ) Is calculated.
Δθ _n-1 = θ _n-1 −θ _n-2 Equation 1

That is, based on the sign of the calculated previous difference value Δθ _n−1 , the electronic control unit 35 determines whether the turning operation of the steering handle 11 was an operation for increasing the steering angle θ at the time of execution of the previous reaction force control program. It can be determined whether or not the operation reduces the angle θ. Specifically, if the sign of the calculated previous difference value Δθ _n-1 is positive, the steering handle 11 is operated in the direction in which the steering angle θ increases (leftward) when the previous reaction force control program is executed. If the sign of the previous difference value Δθ _n−1 is negative, it can be determined that the steering handle 11 is operated in the direction in which the steering angle θ decreases (to the right). When the electronic control unit 35 calculates the previous difference value Δθ _n−1 , the electronic control unit 35 proceeds to step S54.

In step S54, the electronic control unit 35, in accordance with the following equation 2, calculates the steering angle θ _n (hereinafter referred to as the current steering angle θ _n ) input and stored in step S12 by executing the current reaction force control program. A difference value Δθ _{n from the} previous steering angle θ _n-1 (hereinafter referred to as a current difference value Δθ _n ) is calculated.
Δθ _n = θ _n −θ _n-1 Equation 2

That is, the electronic control unit 35, based on the sign of the calculated current difference value [Delta] [theta] _n, the steering wheel 11 in the execution time of this reaction force control program if the sign is positive the current difference value [Delta] [theta] _n is operated in the left direction _If the sign of the current difference value Δθ _n is negative, it can be determined that the steering wheel 11 is operated in the right direction. Then, when the electronic control unit 35 calculates the current difference value Δθ _n , the electronic control unit 35 proceeds to step S55.

In step S55, the electronic control unit 35 multiplies the previous difference value Δθ _n−1 calculated in step S53 by the current difference value Δθ _n calculated in step S54, and the sign of the multiplied value is obtained. It is determined whether or not is negative. That is, the electronic control unit 35 executes the determination process of step S55, so that the turning operation direction of the steering handle 11 differs between the execution time of the previous reaction force control program and the execution time of the current reaction force control program. It is determined whether or not.

Specifically, it is a leftward operation in which the previous difference value Δθ _n-1 is positive at the time of execution of the previous reaction force control program (or a rightward operation in which the difference value Δθ _n-1 is negative), this difference value [Delta] [theta] _n rightward operations that are negative in the execution time of this reaction force control program (or, left direction operation as a differential value [Delta] [theta] _n is positive) when it is, the previous difference value [Delta] [theta] _n-1 The value obtained by multiplying the current difference value Δθ _n is negative. In this case, since the rotation operation direction of the steering handle 11 is reversed (hereinafter, this operation is referred to as a reversal operation), the electronic control unit 35 determines “Yes” and proceeds to step S56.

On the other hand, when the previous reaction force control program is executed, this is a leftward operation in which the previous difference value Δθ _n-1 is positive (or a rightward operation in which the difference value Δθ _n-1 is negative). left operating as a current difference value [Delta] [theta] _n is positive in the execution time of the control program (or the difference value [Delta] [theta] _n is the right direction operation be negative) in the case of the previous difference value [Delta] [theta] _n-1 and the current difference value A value obtained by multiplying Δθ _n is positive. When the current difference value Δθ _n is “0” at the time of execution of the current reaction force control program, the value obtained by multiplying the previous difference value Δθ _n-1 by the current difference value Δθ _n is “0”. Become. In these cases, the electronic control unit 35 does not reverse the rotation operation direction of the steering handle 11 (hereinafter, this operation is referred to as non-inversion operation), or the steering handle 11 is operated to hold the steering wheel 11 by the driver (in the neutral position). Determination is “No” and the process proceeds to step S57.

In step S56, the electronic control unit 35 calculates a gain α by which the current difference value Δθ _n is multiplied in order to reduce the fluctuation amount ΔTf of the friction torque Tf applied to the reversing operation of the steering handle 11. More specifically, in a situation where the steering handle 11 is reversed from a left direction operation (right direction operation) to a right direction operation (left direction operation), the direction in which the applied friction torque Tf is applied is also reversed. At this time, the greater the variation ΔTf of the applied friction torque Tf, the easier it is for the driver to perceive discomfort associated with the reversing operation.

In this case, as will be described later, when the friction torque Tf is calculated and applied according to the change amount of the steering angle θ, that is, the current difference value Δθ _n (proportional), the larger the current difference value Δθ _n is, the larger the friction torque is. The fluctuation amount ΔTf of Tf increases. That is, as the detection resolution when the steering angle sensor 31 detects the steering angle θ (corresponding to the magnitude of the current difference value Δθ _n ) is coarser, the variation amount ΔTf of the friction torque Tf increases. Therefore, when the steering wheel 11 is reversed, the electronic control unit 35 subtracts the change suppression constant A calculated in step S51 according to the following equation 3 in order to reduce the difference value Δθ _n this time. As a result, a new gain α is calculated.
α = α−A Equation 3
Then, after calculating the new gain α, the electronic control unit 35 proceeds to step S60.

In step S57, the electronic control unit 35 multiplies the previous difference value Δθ _n−1 calculated in step S53 and the current difference value Δθ _n calculated in step S54, and the sign of the multiplied value is obtained. It is determined whether or not is positive. That is, the situation in which the electronic control unit 35 executes step S57 is the situation determined as “No” in step S55, that is, the driver performs an operation other than the reversing operation (non-reversing operation or steering operation). It is a situation. Then, the electronic control unit 35 executes the determination process of step S57, so that the turning operation direction of the steering handle 11 is the same between the execution time of the reaction force control program up to the previous time and the execution time of the current reaction force control program. Determine whether you are doing it.

More specifically, if the value obtained by multiplying the previous difference value Δθ _n−1 calculated in step S53 and the current difference value Δθ _n calculated in step S54 is positive, the driver can turn the steering wheel. 11 is continuously non-inverted in one direction (leftward operation or rightward operation). Therefore, the electronic control unit 35 determines “Yes” and proceeds to step S58. On the other hand, if the value obtained by multiplying the previous difference value Δθ _n−1 calculated in step S53 by the current difference value Δθ _n calculated in step S54 is “0”, the current reaction force control program At the time of execution, the driver is holding the steering handle 11. Therefore, the electronic control unit 35 determines “No” and proceeds to step S59.

In step S58, the electronic control unit 35 calculates a gain α to be multiplied by the current difference value Δθ _n in order to return the fluctuation amount ΔTf of the friction torque Tf applied to the non-reversing operation of the steering handle 11 to the normal state. To do. More specifically, in a situation where the steering handle 11 is operated in one direction without being reversed, the direction in which the applied friction torque Tf is applied is also one direction. Therefore, when the turning operation of the steering handle 11 is not reversed, the electronic control unit 35 sets the current difference value Δθ _n to a normal size (in other words, the normal detection resolution of the steering angle sensor 31). ). That is, when the steering wheel 11 is operated in a non-inverted manner, the electronic control unit 35 proceeds to the step S51 according to the following equation 4 so as to increase the gain α by the amount reduced by the step S56, for example. The new gain α is calculated by adding the change suppression constant B calculated in the above.
α = α + B Equation 4
Then, after calculating the new gain α, the electronic control unit 35 proceeds to step S60.

  On the other hand, in step S59, the electronic control unit 35 does not change the friction torque Tf to be applied to the steering operation of the steering handle 11. That is, when the steering handle 11 is being steered, the electronic control unit 35 maintains the current gain α without updating the gain α. Then, the electronic control unit 35 proceeds to step S60.

  In step S60, the electronic control unit 35 executes a known limiter process for the gain α calculated in step S56 or step S57 so that, for example, 0 <α ≦ 1. Then, the electronic control unit 35 proceeds to step S61.

In step S61, the electronic control unit 35 calculates the gain α calculated in step S56 or S58 and subjected to the limiter process in step S60 or the gain α maintained in step S59 this time according to the following formula 5. The current difference value Δθ _{n_new} corrected by multiplying the difference value Δθ _n is calculated.
Δθ _{n_new} = α · Δθ _n ... Formula 5
As a result, in the situation where the steering wheel 11 is reversed, the current difference value Δθ _{n_new} is calculated as a small value because the current difference value Δθ _{n is} multiplied by a small gain α. On the other hand, in a situation where the steering wheel 11 is operated in a non-inverted manner, the current difference value Δθ _{n_new} is calculated as a large value because the gain α having a large value is multiplied with the current difference value Δθ _n . As described above, when the current difference value Δθ _{n_new} is calculated, the electronic control unit 35 proceeds to step S62.

In step S62, the electronic control unit 35 calculates the friction torque Tf using the current difference value Δθ _{n_new} calculated in step S61. Hereinafter, the calculation of the friction torque Tf will be described. Note that the friction torque Tf, the fluctuation amount ΔTf, the detected steering angle θ, the current difference value Δθ _n, and the current difference value Δθ _{n_new} originally have positive and negative signs. Treat as absolute value.

As shown in FIG. 5, the friction torque Tf can be represented by a proportional function having a positive value K as a proportional coefficient with respect to a change in the detected steering angle θ. In other words, according to this proportional function, the current friction torque Tf can be calculated by adding the fluctuation amount ΔTf corresponding to the current difference value Δθ _n to the previously calculated friction torque Tf _n−1 . Therefore, as described above, if the current difference value Δθ _n is fixed at a large value, the fluctuation amount ΔTf of the friction torque Tf also increases, and as a result, the current friction torque Tf perceived by the driver is calculated last time. It becomes larger than the friction torque Tf _n-1 . For this reason, in particular, in a situation where the driver reverses the steering handle 11, it is easy to perceive the fluctuation of the friction torque Tf and to feel uncomfortable.

On the other hand, by using the current difference value Δθ _{n_new} calculated in step S61, the friction torque Tf is calculated using the small current difference value Δθ _{n_new} when the steering wheel 11 is reversed. can do. On the other hand, when the steering wheel 11 is non-inverted, the friction torque Tf can be calculated using the current difference value Δθ _{n_new} having a normal magnitude. That is, the electronic control unit 35 calculates the variation amount ΔTf of the friction torque Tf corresponding to the current difference value Δθ _{n_new} according to the following equation 6. Then, the electronic control unit 35 calculates the friction torque Tf by adding the calculated fluctuation amount ΔTf to the friction torque Tf _n−1 calculated by the previous execution of the reaction force control program according to the following equation (7).
ΔTf = Δθ _{n_new} · K (Formula 6)
Tf = Tf _n-1 + ΔTf Equation 7
However, K in the equation 6 represents the proportional coefficient of the proportional function as described above, and represents the friction torque coefficient value.

  When the friction torque Tf is thus calculated, the electronic control unit 35 proceeds to step S63 and returns to the reaction force control program shown in FIG. Then, the electronic control unit 35 executes step S14 of the reaction force control program.

In step S14, the electronic control unit 35 adds the friction torque Tf calculated in step S62 of the friction vibration reduction calculation routine to the basic reaction force torque Tb calculated in step S12 according to the following equation 8. The target reaction torque Tz is calculated.
Tz = Tb + Tf Equation 8
Then, the electronic control unit 35 proceeds to step S15.

  In step S <b> 15, the electronic control unit 35 controls the operation of the reaction force actuator 13 and applies the target reaction force torque Tz calculated in step S <b> 14 to the steering handle 11 via the steering 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 Tz 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 Tz to the steering handle 11 via the steering input shaft 12.

  As the reaction force actuator 13 is controlled in this manner, the driver can perceive an appropriate reaction force via the steering handle 11. More specifically, when the driver rotates the steering handle 11 (addition operation or return operation), the driver perceives an elastically changing reaction force mainly including the basic reaction force torque Tb. Can do. In addition, when the driver performs the steering operation on the steering handle 11 or a minute turning operation at the neutral position, a reaction force based on the friction torque Tf that fluctuates smoothly can be perceived.

  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 also the actual turning angle δ 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, even when the driver reverses the steering wheel 11, the variation amount ΔTf of the friction torque Tf that varies with vibration is reduced to the lower limit value determined by the gain α. Can do. For this reason, even if the fluctuation of the friction torque Tf actually occurs, it can be made difficult to be perceived by the driver, and a good steering feeling can be ensured. On the other hand, for example, when the driver performs a non-reverse operation of the steering handle 11, in other words, when the steering handle 11 is not vibrating, the fluctuation amount ΔTf of the friction torque Tf is increased to the upper limit value determined by the gain α. can do. For this reason, the driver can perceive the reaction force according to the operation of the steering handle 11, and can ensure a good steering feeling.

Further, as to whether or not vibration is generated in the steering handle 11, it is detected at the sign of the current difference value Δθ _n corresponding to the steering angle θ detected at the current sampling time and at the previous sampling time. On the basis of the sign of the previous difference value Δθ _n−1 corresponding to the steering angle θ, it can be determined that the steering handle 11 is reversed when these signs are different, in other words, vibration is occurring. it can. Further, when the sign of the current difference value Δθ _n is the same as the sign of the previous difference value Δθ _n−1 , it can be determined that the steering handle 11 has been non-inverted, in other words, the vibration has stopped. Thereby, it is not necessary to execute complicated determination processing, and it is possible to determine whether or not vibration is generated in the steering wheel 11 very accurately.

Furthermore, as shown in the equation 6, variation ΔTf of friction torque Tf is detected steering angle theta, and more particularly, a new current difference value calculated by multiplying the gain α to the current difference value [Delta] [theta] _n It is proportional to Δθ _{n_new} . For this reason, every time it is determined that the steering handle 11 is reversely operated and vibration is generated, the gain α is uniformly reduced as shown in Equation 3 above, and the steering handle 11 is not reversely operated. Thus, whenever it is determined that the vibration is stopped, the amount of variation ΔTf of the friction torque Tf can be changed by uniformly increasing the gain α as shown in the equation (4).

  As a result, the fluctuation amount ΔTf of the friction torque Tf can be reliably changed according to the operation state of the steering handle 11. Therefore, even in a situation where vibration is generated in the steering handle 11, it is possible to make it difficult for the driver to perceive the fluctuation of the friction torque Tf, and it is possible to ensure a good steering feeling. On the other hand, in a situation where vibration does not occur in the steering handle 11, the driver can perceive a reaction force according to the operation of the steering handle 11, and can ensure a good steering feeling.

b. Second Embodiment In the first embodiment, the electronic control unit 35 executes the friction vibration reduction calculation routine to calculate and change the new current difference value Δθ _{n_new} in the equation 6 to change the friction torque Tf. The amount ΔTf was calculated, and in particular, it was implemented so as to suppress the uncomfortable feeling caused by the fluctuation of the friction torque Tf during the reversing operation. By the way, as apparent from the equation 6, instead of changing the current difference value Δθ _{n_new} related to the detected steering angle θ, by changing the friction torque coefficient value adopted as the proportional coefficient, The uncomfortable feeling caused by the fluctuation of the friction torque Tf can be suppressed. Hereinafter, the second embodiment will be described in detail.

  Also in the second embodiment, as in the first embodiment, the electronic control unit 35 executes the reaction force control program shown in FIG. However, in the second embodiment, the frictional vibration reduction calculation routine executed in step S13 is different from that in the first embodiment. Therefore, in the following description, only the frictional vibration reduction calculation routine according to the second embodiment will be described in detail.

In step S13 of the reaction force control program, the electronic control unit 35 executes the frictional vibration reduction calculation routine shown in FIG. 6 to suppress the uncomfortable feeling felt by the driver due to the variation of the friction torque Tf, and good steering. Try to get a feeling. That is, the electronic control unit 35 starts execution of the frictional vibration reduction calculation routine in step S100. In step S101, the electronic control unit 35 obtains the steering angle θ _(i) (hereinafter, this time steering angle θ _{( i)} hereinafter) and the steering angle theta _(i-1 stored by entering the last execution of the reaction force control _program) (hereinafter, the difference value Δθ of the previous steering angle theta _(i-1) hereinafter) _(i) ( Hereinafter, the current difference value Δθ _(i) is calculated.
Δθ _(i) = θ _(i) −θ _(i-1) … Equation 9

That is, the electronic control unit 35, based on the sign of the computed current difference value [Delta] [theta] _(i), the steering wheel 11 in the execution time of the reaction force control program code if the positive current the current difference value [Delta] [theta] _(i) is If the sign of the calculated current difference value Δθ _(i) is negative in the direction in which the steering angle θ increases (leftward ₎ , the steering handle 11 moves in the direction in which the steering angle θ decreases (in the right direction). ) It can be determined that it is being operated. Then, when the electronic control unit 35 calculates the current difference value Δθ _(i) , the process proceeds to step S102.

In step S102, the electronic control unit 35 executes past friction value reduction calculation routines up to the previous time, and the past difference value Δθ * ₍₁₎ to difference value Δθ * ₍ stored as the past history in step S108 described later _{). n)} , the difference value Δθ * ₍₁₎ stored last (hereinafter referred to as the previous difference value Δθ * ₍₁₎ ) and the current difference value θ _(i) calculated in step S101 are multiplied by each other, It is determined whether or not the sign of this multiplied value is negative. In other words, the electronic control unit 35 executes the determination process in step S102, so that the turning operation direction of the steering handle 11 is changed between the execution time of the reaction force control program up to the previous time and the execution time of the current reaction force control program. Determine whether they are different.

Specifically, the leftward operation in which the previous difference value Δθ * ₍₁₎ is positive at the time of execution of the reaction force control program up to the previous time (or the rightward operation in which the previous difference value Δθ * ₍₁₎ is negative _). ) And when the current reaction force control program is executed, the current difference value Δθ _(i) is a rightward operation (or a leftward operation where the current difference value Δθ _(i) is positive). Is a negative value obtained by multiplying the previous difference value Δθ * ₍₁₎ and the current difference value Δθ _(i) . In this case, since the steering handle 11 is reversed by the driver, the electronic control unit 35 determines “Yes” and proceeds to step S103.

On the other hand, it is a leftward operation in which the previous difference value Δθ * ₍₁₎ is positive (or a rightward operation in which the previous difference value Δθ * ₍₁₎ is negative ₎ at the time of execution of the reaction force control program up to the previous time, If the current difference value Δθ _(i) is a leftward operation (or a rightward operation where the current difference value Δθ _(i) is negative) at the time of execution of the current reaction force control program, A value obtained by multiplying the difference value Δθ * ₍₁₎ by the current difference value Δθ _(i) is positive. In addition, when the current difference value Δθ _(i) is “0” at the time of execution of the current reaction force control program, a value obtained by multiplying the previous difference value Δθ * ₍₁₎ and the current difference value Δθ _(i). Becomes “0”. In these cases, the electronic control unit 35 determines “No” and proceeds to step S104 because the driver performs the non-reverse operation or the steering operation (including the holding at the neutral position).

In step S103, the electronic control unit 35 calculates the friction torque coefficient value K _(i) in order to reduce the fluctuation amount ΔTf of the friction torque Tf applied to the reversing operation of the steering handle 11. More specifically, in the second embodiment as well, the variation ΔTf and the friction torque Tf are calculated according to the equations 6 and 7, as in the first embodiment. Therefore, also in the second embodiment, the greater the variation amount ΔTf of the applied friction torque Tf, the easier it is for the driver to perceive a sense of discomfort associated with the reversing operation.

By the way, in this case, the larger the friction torque coefficient value K employed as the proportional coefficient in Equation 6 is, that is, the greater the gradient of the proportional function, the greater the variation ΔTf of the friction torque Tf with respect to the change in the detected steering angle θ. Becomes larger. Therefore, when the steering wheel 11 is reversed, the electronic control unit 35 calculates the friction torque coefficient value K _(i) according to the following equation 10 in order to reduce the gradient of the proportional function.
K _(i) = K _(i-1) −ΔK _{down (} 10 ₎

However, K _{(i-1) in} Equation 10 represents a friction torque coefficient value calculated by executing the friction vibration reduction calculation routine up to the previous time, and ΔK _down represents a decrease in the friction torque coefficient value set experimentally in advance. It represents the amount of change over time. Then, after calculating the friction torque coefficient value K _(i) , the electronic control unit 35 proceeds to step S107. When the calculated friction torque coefficient value K _(i) is less than the preset lower limit value KL of the friction torque coefficient value, the friction torque coefficient value K _(i) is set to the friction torque coefficient value KL.

On the other hand, in step S104, the electronic control unit 35 calculates the current difference value Δθ _(i) calculated in step S101 and the past difference value Δθ * ₍₁₎ to difference value Δθ stored in step S108 described later. * _(n) is sequentially multiplied, and it is determined whether there is any of the multiplied values with a positive sign. That is, as a situation where the electronic control unit 35 executes step S104, the situation determined as “No” in step S102, that is, the driver performs an operation other than the reversing operation (non-reversing operation or steering operation). It is a situation. Then, the electronic control unit 35 executes the determination process of step S104, so that the turning operation direction of the steering handle 11 is the same between the execution time of the reaction force control program up to the previous time and the execution time of the current reaction force control program. Determine whether you are doing it.

More specifically, if the value obtained by sequentially multiplying the current difference value Δθ _(i) and the past difference value Δθ * ₍₁₎ to the difference value Δθ * _(n) is positive, the steering wheel 11 is moved by the driver. A non-inverted operation (increasing operation or returning operation) is continued in one direction. Therefore, the electronic control unit 35 determines “Yes” and proceeds to step S105. On the other hand, if the value obtained by sequentially multiplying the current difference value Δθ _(i) and the past difference value Δθ * ₍₁₎ to the difference value Δθ * _(n) is “0”, the current reaction force control program is executed. In FIG. 2, the driver is holding the steering handle 11. For this reason, the electronic control unit 35 determines “No” and proceeds to step S106.

In step S105, the electronic control unit 35 calculates a friction torque coefficient value K _(i) for returning the fluctuation amount ΔTf of the friction torque Tf applied to the non-inversion operation of the steering handle 11 to the normal state. More specifically, in a situation where the steering handle 11 is operated in one direction without being reversed, the direction in which the applied friction torque Tf is applied is also one direction. For this reason, the electronic control unit 35 sets the friction torque coefficient value K _(i) to a normal magnitude when the turning operation of the steering handle 11 is not reversed. That is, when the steering wheel 11 is non-inverted, the electronic control unit 35 calculates the friction torque coefficient value K _(i) according to the following equation 11 in order to increase the slope of the proportional function.
K _(i) = K _(i-1) + ΔK _{up (} Formula 11)

However, K _{(i-1) in} Equation 11 represents a friction torque coefficient value calculated by executing the friction vibration reduction calculation routine _up to the previous time, and ΔK _up is an increase in the friction torque coefficient value set experimentally in advance. It represents the amount of change over time. Then, after calculating the friction torque coefficient value K _(i) , the electronic control unit 35 proceeds to step S107. Incidentally, the calculated friction torque coefficient values K _(i) is, when exceeding the upper limit KH preset friction torque coefficient values, the friction torque coefficient values K _(i) is a friction torque coefficient value KH.

On the other hand, in step S106, the electronic control unit 35 does not update the fluctuation amount ΔTf of the friction torque Tf to be applied to the steering operation of the steering handle 11. That is, when the steering handle 11 is steered, the electronic control unit 35 maintains the friction torque coefficient value K _(i) according to the following equation 12 without updating the slope of the proportional function.
K _(i) = K _(i-1) ... Formula 12
Then, the electronic control unit 35 proceeds to step S107.

In step S107, the electronic control unit 35 determines whether or not the current difference value Δθ _(i) calculated in step S101 is “0”. That is, if the current difference value Δθ _(i) is “0”, the electronic control unit 35 determines “Yes” and proceeds to step S109. On the other hand, if the current difference value Δθ _(i) is not “0”, the electronic control unit 35 determines “No” and proceeds to step S108.

In step S108, the electronic control unit 35 stores the current difference value Δθ _(i) that is not “0” calculated in step S101 as a past history. Specifically, the electronic control unit 35 updates the current difference value Δθ _(i) calculated by executing the current frictional vibration reduction calculation routine as a new previous difference value Δθ * ₍₁₎ , and updates the previous previous value. The difference value Δθ * ₍₁₎ is updated as a new difference value Δθ * ₍₂₎ , and the previous difference value Δθ * _(n−1) is updated and stored as a new difference value Δθ * _(n) . That is, the difference values Δθ * ₍₁₎ to Δθ * _(n) stored as the past history in step S108 are all stored as difference values other than “0”. Then, when the electronic control unit 35 updates and stores the past difference value Δθ * ₍₁₎ to difference value Δθ * _(n) , the process proceeds to step S109.

In step S109, the electronic control unit 35 calculates the friction torque Tf according to the following formulas 13 and 14 similar to the formulas 6 and 7 in the first embodiment.
ΔTf = Δθ _(i) · K _(i) Equation 13
Tf = Tf _n-1 + ΔTf Equation 14
In this case, when it is determined “Yes” in step S107, that is, when the current difference value Δθ _(i) is “0”, the fluctuation amount ΔTf calculated according to the equation 13 becomes “0”. Therefore, when the steering handle 11 is being steered, the friction torque Tf does not change.

  When the friction torque Tf is thus calculated, the electronic control unit 35 proceeds to step S110 and returns to the reaction force control program shown in FIG. As in the first embodiment, the electronic control unit 35 executes the respective step processes after step S14 of the reaction force control program to drive and control the reaction force actuator 13 and steer via the steering input shaft 12. A reaction force corresponding to the target reaction force torque Tz is applied to the handle 11.

  As can be understood from the above description, in this second embodiment, since the variation amount ΔTf of the friction torque Tf is proportional to the detected steering angle θ, the friction torque coefficient value K representing the inclination in the proportional relationship is obtained. Can be used to change. That is, in this second embodiment, every time it is determined that vibrations in the operation direction of the steering handle 11 are generated, the friction torque coefficient value K is uniformly reduced according to the above equation 10, and the steering handle 11 is operated. Every time it is determined that the vibration in the direction is stopped, the friction torque coefficient value K can be increased uniformly according to the equation 11 to change the fluctuation amount ΔTf of the friction torque Tf.

Thereby, the fluctuation amount ΔTf of the friction torque Tf can be reliably changed to the lower limit value or the upper limit value determined by the friction torque coefficient value K in accordance with the operation state of the steering handle 11. Therefore, even in a situation where vibration is generated in the steering handle 11, it is possible to make it difficult for the driver to perceive the fluctuation of the friction torque Tf, and it is possible to ensure a good steering feeling. On the other hand, in a situation where vibration does not occur in the steering handle 11, the driver can perceive a reaction force according to the operation of the steering handle 11, and can ensure a good steering feeling. Therefore, also in the second embodiment, the same effect as in the first embodiment can be obtained. In the second embodiment as well, the friction torque coefficient values ΔK _up and ΔK _down are the same as the change suppression constants A and B shown in FIGS. 4A and 4B of the first embodiment. Can be calculated using substantially the same map (ΔK _up corresponds to B and ΔK _down corresponds to A).

  The implementation of the present invention is not limited to the above-described embodiments, and various modifications can be made without departing from the object of the present invention.

For example, in the first embodiment, the current difference value Δθ _n is multiplied by the gain α to calculate the fluctuation amount ΔTf using the new current difference value Δθ _{n_new} , and the friction torque is calculated using the fluctuation amount ΔTf. Implemented to calculate Tf. On the other hand, in the second embodiment, the variation amount ΔTf is calculated by increasing or decreasing the friction torque coefficient value K _(i) , and the friction torque Tf is calculated using the variation amount ΔTf. However, instead of calculating the variation ΔTf by separately changing the current difference value Δθ _{n_new} and the friction torque _coefficient value K _(i) in this way, the current difference value Δθ _{n_new} and the friction torque _coefficient value K ₍ It is also possible to calculate the variation ΔTf by changing _i) at the same time.

As described above, when the current difference value Δθ _{n_new} and the friction torque _coefficient value K _(i) are changed at the same time, for example, when the variation amount ΔTf is calculated according to the equation 6, the variation amount ΔTf is calculated more finely. Can do. Therefore, even when the driver reverses the steering handle 11, the fluctuation of the friction torque Tf can be suppressed well, and the driver can drive with good steering feeling without feeling uncomfortable. can do.

  Further, in each of the above embodiments, a steering-by-wire type steering device is used as a steering device in which the steering input shaft 12 and the steering output shaft 22 are relatively rotatable, and a friction torque Tf that forms a reaction torque in the steering device. Was set and controlled according to the turning operation state of the steering handle 11. However, as a steering device in which the steering input shaft and the steering output shaft can rotate relative to each other, for example, a friction torque that forms a reaction force torque of a transmission device having a variable transmission ratio is appropriately set according to the turning operation state of the steering handle. It is also possible to change.

  In this case, for example, the reaction force is changed by appropriately changing the ratio (transmission ratio) of the turning output shaft to the turning amount of the steering input shaft by the transmission ratio variable mechanism according to the turning operation state of the steering handle. The friction torque forming the torque can be appropriately changed according to the turning operation state of the steering handle. Further, for example, by changing the assist amount of the assist mechanism (electric motor or hydraulic mechanism) for reducing the turning operation force of the steering handle 11 by the driver according to the turning operation state of the steering handle, the reaction force The friction torque forming the torque can be appropriately changed according to the turning operation state of the steering handle. Therefore, even with a steering device that employs a method other than the steering-by-wire method, the driver can drive with good steering feeling without feeling uncomfortable.

  In each of the above embodiments, the steering handle 11 that is rotated 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 embodiments, the left and right front wheels FW1 and 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 common to each embodiment of the present invention. It is a flowchart of the reaction force control program performed by the electronic control unit of FIG. 4 is a flowchart of a frictional vibration reduction calculation routine executed by the electronic control unit of FIG. 1 according to the first embodiment of the present invention. (A), (b) is a graph which shows the relationship between a basic reaction force torque and a change suppression constant. It is a graph which shows the relationship between a steering angle and a friction torque. 6 is a flowchart of a frictional vibration reduction calculation routine executed by the electronic control unit of FIG. 1 according to the second embodiment of the present invention.

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, 36, 37 ... Drive circuit, 36a, 37a ... Current detector

Claims (8)

The present invention is applied to a vehicle having a steering handle operated by a driver and a reaction force generating device for generating and applying a reaction force torque to the operation of the steering handle. In the reaction force control device for setting and controlling the reaction force torque applied by the reaction force generation device according to
An operation input value detecting means for detecting an operation input value of the driver for the steering wheel at every predetermined sampling time;
Steering wheel vibration generation determination means for determining whether vibration in the operation direction of the steering wheel is generated using the past history of the operation input value detected by the operation input value detection means;
When vibration is generated in the steering wheel by the steering wheel vibration generation determination means, the amount of variation between the reaction force torques corresponding to the operation input value detected at each predetermined sampling time is calculated. When the steering wheel vibration occurrence determination means does not generate vibrations to the steering wheel, the variation amount is uniformly reduced to a preset upper limit value. A reaction torque fluctuation amount changing means for increasing and changing,
And a target reaction force torque setting means for setting a target reaction force torque generated and applied by the reaction force generator using the fluctuation amount changed by the reaction force torque fluctuation amount changing means. Reaction force control device. In the reaction force control device according to claim 1,
The steering handle vibration occurrence determining means is
The operation input value detected at the current sampling time by the operation input value detection means using the past history of the difference values between the operation input values detected at predetermined sampling times by the operation input value detection means. When the sign of the current difference value corresponding to the above and the sign of the past difference value corresponding to the operation input value detected at a past sampling time a predetermined number of times are different from each other, vibration in the operation direction of the steering wheel is generated. It is determined that the vibration has occurred, and it is determined that the vibration in the operation direction of the steering wheel is stopped when the sign of the current difference value and the sign of the past difference value are all the same. Reaction force control device. In the reaction force control device according to claim 1 or 2,
The reaction torque fluctuation amount changing means is
The fluctuation amount proportional to the operation input value detected by the operation input value detection means is
Based on the determination by the steering handle vibration generation determination means, it is uniformly reduced every time it is determined that vibration in the operation direction of the steering handle is generated, and the vibration in the operation direction of the steering handle is stopped. A gain value that uniformly increases every time it is determined to be present is changed using a new operation input value obtained by multiplying the operation input value detected at a predetermined sampling time by the operation input value detection means. A reaction force control device. In the reaction force control device according to claim 1 or 2,
The reaction torque fluctuation amount changing means is
The fluctuation amount proportional to the operation input value detected by the operation input value detection means is
Using the friction torque coefficient representing the slope in the proportional relationship,
Based on the determination by the steering wheel vibration generation determination means, the friction torque coefficient value is uniformly lowered every time it is determined that vibration in the operation direction of the steering wheel is generated, A reaction force control device, wherein the frictional torque coefficient value is changed by uniformly increasing each time it is determined that the vibration is stopped. In a reaction force setting method for setting a reaction force torque to be applied to an operation of a steering wheel of a vehicle by a driver according to an operation state of the steering wheel,
A driver's operation input value for the steering wheel is detected at each predetermined sampling time;
Using the past history of the detected operation input value to determine whether vibration in the operation direction of the steering wheel has occurred,
When vibration is generated in the steering handle, the fluctuation amount between the reaction force torques corresponding to the operation input value detected at each predetermined sampling time is reduced to a preset lower limit value. When the vibration is not generated in the steering wheel, the variation amount is uniformly increased up to a preset upper limit value and changed,
A reaction force setting method comprising: setting a target reaction force torque to be applied to the operation of the steering wheel using the changed amount of change. In the reaction force setting method according to claim 5,
Using the past history of the difference value between each operation input value detected at each predetermined sampling time, the sign of the current difference value corresponding to the operation input value detected at the current sampling time and the predetermined time It is determined that vibration in the operation direction of the steering wheel is occurring when at least one of the signs of the past difference values corresponding to the operation input values detected at the past sampling time is different, and the current difference value And a sign of the past difference value are all the same, it is determined that the vibration in the operation direction of the steering wheel is stopped. In the reaction force setting method according to claim 5 or 6,
The fluctuation amount is proportional to the detected operation input value,
The amount of variation is
A gain that decreases uniformly every time it is determined that vibration in the operation direction of the steering wheel is generated, and increases uniformly every time it is determined that vibration in the operation direction of the steering wheel stops. A reaction force setting method, wherein a value is changed by using a new operation input value obtained by multiplying the operation input value detected at each predetermined sampling time. In the reaction force setting method according to claim 5 or 6,
The fluctuation amount is proportional to the detected operation input value,
The amount of variation is
Using the friction torque coefficient value representing the slope in the proportional relationship,
Each time it is determined that vibration in the steering handle operating direction is generated, the friction torque coefficient value is uniformly reduced, and each time it is determined that vibration in the steering handle operating direction is stopped, A reaction force setting method, wherein the friction torque coefficient value is changed by uniformly increasing.

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