JP2010214988A - Vehicular steering device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a vehicular steering device capable of fluctuating the reaction force to be adequately imparted to a steering wheel according to the turning operation of wheels for suppressing the behavior change caused by the disturbance to be applied in the transverse direction of a vehicle. <P>SOLUTION: A basic reaction force computation unit 201 inputs the target lateral acceleration G<SP>*</SP>calculated by a target lateral acceleration computation unit 101, inputs the steering angle θ<SB>MA</SB>detected by a steering angle sensor 31, and calculates the target basic steering reaction force torque Tz<SP>*</SP>. An additional assist force computation unit 202 inputs the deviation ΔG calculated by the lateral acceleration deviation computation unit 103, and calculates the target additional assist torque Ta<SP>*</SP>for assisting the turning operation of a steering wheel 11 by a driver in the direction against the disturbance such as cross wind. A target reaction force computation unit 203 adds the basic steering reaction force torque Tz<SP>*</SP>to the additional assist torque Ta<SP>*</SP>, and calculates the target reaction force torque Tt<SP>*</SP>(=Tz<SP>*</SP>+Ta<SP>*</SP>). <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a vehicle steering apparatus that steers and controls wheels so as to travel stably against disturbance applied in a lateral direction.

  Conventionally, for example, as shown in Patent Document 1, a vehicle steering apparatus is known. The conventional vehicle steering apparatus includes a first target turning angle setting unit that sets a first target turning angle according to the detected steering angle, and a second target turning angle according to only the detected yaw rate. A second target turning angle setting unit that sets the target reaction force, a target reaction force setting unit that sets a control amount for the reaction force motor according to the first target turning angle and the second target turning angle, and a second target turning And a filter provided between the angle setting unit and the reaction force motor. The filter removes a frequency component higher than a predetermined frequency, thereby suppressing the influence on the steering reaction force caused by the active steering by the steering motor.

JP 2006-321471 A

  By the way, when the active steering control is performed as in the conventional vehicle steering device described above, in a situation where the driver does not have to operate the steering handle and correct the behavior of the vehicle without being aware of the occurrence of disturbance. It is preferable that the force does not fluctuate. However, in situations where the driver himself needs to correct the behavior of the vehicle by operating the steering wheel, for example, in a situation where a side wind disturbance occurs and the driver operates the steering wheel in addition to active steering, If the accompanying reaction force does not fluctuate, the driver may feel a sense of discomfort by perceiving a behavior change larger than the behavior change of the vehicle by his / her own operation immediately after the side wind disturbance no longer exists.

  That is, in this case, the reaction force does not fluctuate due to the active steering, so the driver may perceive a behavior change that is as large as the vehicle behavior change due to the active steering, and may feel uncomfortable. Therefore, in a situation where the driver operates the steering wheel in addition to the active steering, it is desirable to give some variation in reaction force.

  In addition, when active steering control is executed, a time delay occurs because the steering control is started after the target turning angle is calculated at the time when the behavior change of the vehicle occurs, and further, the active steering control is performed. There is also a time delay from when the wheel is steered by control until the vehicle behavior changes. Therefore, in addition to active steering, when the reaction force varies in a situation where the driver operates the steering wheel, the variation changes so that the driver can quickly (naturally) operate the steering wheel against disturbance generated by the driver. It is desirable to give

  The present invention has been made to cope with the above-described problem, and the object thereof is appropriately given to the steering wheel in accordance with the steering operation of the wheel that suppresses the behavior change due to the disturbance applied in the lateral direction of the vehicle. An object of the present invention is to provide a vehicle steering apparatus that varies the reaction force.

  In order to achieve the above object, the present invention is characterized in that a steering handle operated to steer a vehicle, a reaction force actuator that applies a reaction force to the operation of the steering handle, and a wheel are steered. Steering actuators, physical quantity detection means for detecting actual physical quantities generated in the vehicle body due to disturbance applied in the lateral direction of the vehicle, and calculation of target physical quantities for the physical quantities generated in the vehicle body according to the operation of the steering wheel Target physical quantity calculating means, command value setting means for setting a command value according to the target physical quantity calculated by the target physical quantity calculating means, command value set by the command value setting means, and the detected actual physical quantity A steering apparatus for a vehicle, comprising: a steering control unit that drives the steering actuator to steer the wheel based on the deviation from the calculated target physical quantity. And a support force for calculating a force for supporting operation of the steering wheel in a direction against a disturbance applied in a lateral direction of the vehicle based on a deviation between the detected actual physical quantity and the calculated target physical quantity. Computation means, and reaction force control means for driving the reaction force actuator based on a target reaction force obtained by adding the calculated assisting force to the reaction force applied to the operation of the steering wheel It is in.

  In this case, a filter that passes only a frequency component higher than a predetermined frequency out of the deviation between the detected actual physical quantity and the calculated target physical quantity is further provided, and the support force calculation means passes through the filter. The assisting force may be calculated based on the deviation having a high frequency component. In these cases, the physical quantity may be, for example, a lateral acceleration generated in the vehicle width direction of the vehicle body or a yaw rate generated around the center of gravity of the vehicle body.

  According to these, the support force calculating means is based on a deviation (difference) between the detected actual physical quantity (for example, lateral acceleration or yaw rate) and the calculated target physical quantity (for example, target lateral acceleration or target yaw rate), It is possible to calculate a force that assists in operating the steering wheel in a direction against a disturbance applied in the lateral direction of the vehicle. In this case, based on a deviation (difference) having a high-frequency component, it is possible to calculate a force that assists in operating the steering wheel in a direction against a disturbance applied in the lateral direction of the vehicle. The reaction force control means adds the assisting force calculated for the reaction force applied to the steering wheel operation (subtracts when the assisting force is in the reverse direction) based on the target reaction force. The reaction force actuator can be driven.

  Therefore, when the wheel is steered by the steering actuator (that is, when it is actively steered), the steering handle is operated in a direction against the disturbance applied in the lateral direction of the vehicle in accordance with the steering operation. It is possible to apply a force to assist the steering wheel to the steering wheel. As a result, the driver can operate the steering wheel while perceiving the applied assisting force. Therefore, even when the driver himself operates the steering wheel to correct the behavior of the vehicle, It becomes difficult to memorize discomfort with behavioral changes.

  In addition, since the assisting force can be applied to the steering wheel, it is possible to prompt the driver to operate the steering wheel in a direction that appropriately resists disturbance. Furthermore, the assisting force calculated based on the deviation having the high frequency component is applied to the steering wheel, in other words, the assisting force based on the deviation having the low frequency component is not applied to the steering wheel to the driver. On the other hand, it is possible to prompt the operation of the steering handle in a direction that appropriately resists disturbance. Thus, regardless of driving experience, the driver can quickly (naturally) operate the steering wheel, and can quickly correct the behavior of the vehicle.

1 is an overall system configuration diagram of a vehicle steering apparatus common to each embodiment of the present invention. FIG. 2 is a block diagram illustrating a control process executed by the steering reaction force ECU and the steering ECU in FIG. 1 according to the first embodiment of the present invention. 3 is a reference map for calculating a target lateral acceleration based on a steering angle and a vehicle speed. It is a reference map for calculating a spring reaction force torque component based on a target lateral acceleration. It is a reference map for calculating a friction reaction force torque component based on a steering angular velocity. It is a reference map for calculating a viscous reaction force torque component based on a steering angular velocity. It is a reference map for calculating a target additional assist torque based on a deviation between a target lateral acceleration and an actual lateral acceleration. It is a graph for demonstrating the condition where the driver | operator with a standard driving technique and driving experience corrects the behavior of a vehicle when target additional assist torque is not provided. It is a graph for demonstrating the situation where the driver | operator who has a standard driving technique and driving experience when target additional assist torque is provided corrects the behavior of a vehicle. It is a graph for demonstrating the situation where the driver | operator who has the driving skill and rich driving experience when the target additional assist torque is not applied and who is familiar with driving corrects the behavior of the vehicle. It is a graph for demonstrating the situation where the driver | operator who has the driving skill and rich driving experience when target additional assist torque is provided, and who is familiar with driving corrects the behavior of the vehicle. FIG. 8 is a block diagram illustrating a control process executed by the steering reaction force ECU and the steering ECU in FIG. 1 according to the second embodiment of the present invention. A driver who is familiar with driving with excellent driving technology and abundant driving experience when the target additional assist torque is applied based on the deviation between the target lateral acceleration having only high frequency components and the actual lateral acceleration. It is a graph for demonstrating the condition which corrects behavior.

a. First Embodiment 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 system configuration of a vehicle steering apparatus common to the embodiments.

  This vehicle steering device mechanically includes a steering operation device 10 that is steered by a driver, and a steering device 20 that steers left and right front wheels FW1 and FW2 as steered wheels according to the steering operation of the driver. A separate steering-by-wire system is used. The steering operation device 10 includes a steering handle 11 as an operation unit that is rotated by a driver. The steering handle 11 is fixed to the upper end of the steering input shaft 12, and a steering reaction force electric motor 13 for generating a reaction force incorporating a speed reduction mechanism is assembled to the lower end of the steering input shaft 12. This steering reaction force electric motor 13 corresponds to the reaction force actuator of the present invention.

  The steered device 20 includes a steered shaft 21 that extends in the left-right direction of the vehicle. The left and right front wheels FW1, FW2 are connected to both ends of the steered shaft 21 via tie rods 22a, 22b and knuckle arms 23a, 23b so as to be steerable. The left and right front wheels FW1 and FW2 are steered left and right by the displacement of the steered shaft 21 in the axial direction. On the outer periphery of the turning shaft 21, a turning electric motor 24 assembled in a housing (not shown) is provided. The rotation of the steered electric motor 24 is decelerated by the screw feed mechanism 26 and is converted into an axial displacement of the steered shaft 21. This steering electric motor 24 corresponds to the steering actuator of the present invention.

Next, the electric control device 30 that controls the rotational drive of the steering reaction force electric motor 13 and the steering electric motor 24 will be described. The electric control device 30 includes a steering angle sensor 31, a turning angle sensor 32, a vehicle speed sensor 33, and a lateral acceleration sensor 34. The steering angle sensor 31 is a steering angle detection means for detecting the steering angle of the steering handle 11 and is assembled to the steering input shaft 12 to detect the rotation angle from the reference point of the steering handle 11 to detect the steering angle θ _MA. A signal representing is output.

  The steered angle sensor 32 is a steered angle detecting means for detecting the steered angle of the steered wheels. The steered angle sensor 32 detects the amount of axial displacement from the reference point of the steered shaft 21, and turns the left and right front wheels FW1, FW2. A signal representing the steering angle δ is output. Here, the rotation angle of the rotor of the electric motor 24 for turning is a value corresponding to the amount of movement of the turning shaft 21 in the axial direction, that is, the amount of change in the turning angle δ. Therefore, the turning angle sensor 32 in the present embodiment includes a relative angle sensor (for example, a resolver sensor) that detects a rotation angle with respect to the reference position of the rotor of the electric motor 24 for turning, and an absolute angle sensor for giving the reference position. (For example, an encoder), and the turning angle δ is detected from the rotation angle of the turning electric motor 24 obtained by both sensors. The vehicle speed sensor 33 outputs a vehicle speed signal representing the vehicle speed V that is the traveling speed of the vehicle. The lateral acceleration sensor 34 corresponds to the physical quantity detection means of the present invention, and outputs a signal representing the lateral acceleration G that is fixed to the vehicle body and works in the vehicle width direction.

Note that the steering angle θ _MA , the actual turning angle δ, and the lateral acceleration G described above can identify their directions. For example, the steering angle θ _MA is directed leftward with respect to the reference point, or acts leftward. It is represented by a positive value, and when it is directed rightward or acting rightward, it is represented by a negative value. In the present specification, when the magnitude relationship between detected values is discussed without distinguishing the direction, the magnitude of the absolute value is discussed.

  The electric control device 30 includes a steering reaction force electronic control unit (hereinafter simply referred to as a steering reaction force ECU) 35 and a steering electronic control unit (hereinafter simply referred to as a steering ECU). 36). Each of the steering reaction force ECU 35 and the steering ECU 36 includes a microcomputer including a CPU, a ROM, a RAM, and the like as main components. A steering angle sensor 31 and a vehicle speed are provided on the input side of the steering reaction force ECU 35. A sensor 33 is connected, and a steering angle sensor 31, a turning angle sensor 32, a vehicle speed sensor 33, and a lateral acceleration sensor 34 are connected to the input side of the steering ECU 36.

  A drive circuit 37 for driving and controlling the steering reaction force electric motor 13 is connected to the output side of the steering reaction force ECU 35, and the steering electric motor 24 is connected to the output side of the steering ECU 36. A drive circuit 38 for driving control is connected. In the drive circuits 37 and 38, current detectors 37a and 38a are provided for detecting drive currents flowing through the electric motors 13 and 24, respectively. The drive currents detected by the current detectors 37a and 38a are fed back to the steering reaction force ECU 35 and the steering ECU 36 in order to drive and control the electric motors 13 and 24, respectively.

  Next, with respect to the operation of the vehicle steering apparatus according to the first embodiment configured as described above, the function block diagram of FIG. 2 showing the functions realized by the computer program processing of the steering reaction force ECU 35 and the steering ECU 36 is shown. The details will be described. In order to facilitate understanding, first, the turning angle control by the turning ECU 36 will be described.

The steering ECU 36 includes a target lateral acceleration calculation unit 101. The target lateral acceleration calculation unit 101 stores a reference map for calculating the target lateral acceleration G ^* based on the steering angle θ _MA and the vehicle speed V, as shown in FIG. The target lateral acceleration calculation unit 101 inputs the steering angle θ _MA detected by the steering angle sensor 31 and the vehicle speed V detected by the vehicle speed sensor 33, and calculates the target lateral acceleration G ^* by referring to this reference map. The target lateral acceleration G ^* is a target value of the lateral acceleration of the vehicle body generated by the lateral movement of the vehicle. In this case, the target lateral acceleration G ^* increases as the steering angle θ _MA increases, and increases as the vehicle speed V increases. In this embodiment, the target lateral acceleration G ^* is calculated using the reference map, but instead of the reference map, the target lateral acceleration G ^* that changes according to the steering angle θ _MA and the vehicle speed V is defined. This function may be stored, and the target lateral acceleration G ^* may be calculated using this function. In the present embodiment, the target lateral acceleration G ^* is calculated from the steering angle θ _MA and the vehicle speed V, but the target lateral acceleration G ^* is obtained only from the steering angle θ _MA without being related to the vehicle speed V. Also good. In this case, the calculation load of the steering ECU 36 can be reduced by merely obtaining the target lateral acceleration G ^* that is directly proportional to the steering angle θ _MA . The target lateral acceleration calculation unit 101 corresponds to the target physical quantity calculation means of the present invention.

Further, the steering ECU 36 includes a feed-forward calculation unit 102, a lateral acceleration deviation calculation unit 103, a PI control unit 104, and a target turning angle calculation unit 105 in order to calculate the target turning angle δ ^* . The target lateral acceleration G ^* calculated by the target lateral acceleration calculation unit 101 is input to the feedforward calculation unit 102 and the lateral acceleration deviation calculation unit 103. The feedforward calculation unit 102 inputs the target lateral acceleration G ^* and calculates the feedforward control value δ _ff of the turning angle using the following formula 1.

なお、前記式２中のG_γ(V)は車速Vごとに設定される転舵角δ−ヨーレートγの定常ゲインを表し、ω_n(V)は車速Vごとに設定される車両の応答の固有振動数（共振周波数）を表し、ζは車両の応答の減衰比を表す。また、前記式２中のsはラプラス演算子を表す。また、前記式２中のT_y1，T_y2はそれぞれ下記式３，４で表される。

ここで、前記式３中のL_rは車両重心点と後車軸間の距離を表す。また、前記式４中のI_zは車両のヨーイング慣性モーメントを表し、K_rは車両後輪のコーナリングパワーを表し、Lは車両のホイールベースを表す。 However, F _δg (s) in the equation 1 is a transfer function having the turning angle δ as an input and the lateral acceleration G as an output as expressed by the following equation 2, for example.

In the equation 2, G _γ (V) represents the steady gain of the turning angle δ−yaw rate γ set for each vehicle speed V, and ω _n (V) represents the vehicle response set for each vehicle speed V. It represents the natural frequency (resonance frequency), and ζ represents the damping ratio of the vehicle response. Further, s in the formula 2 represents a Laplace operator. Further, T _y1 and T _y2 in the formula 2 are represented by the following formulas 3 and 4, respectively.

Here, L _{r in} Equation 3 represents the distance between the vehicle center of gravity and the rear axle. Further, I _z in the equation 4 represents the yawing moment of inertia of the vehicle, K _r represents the cornering power of the rear wheel of the vehicle, and L represents the wheel base of the vehicle.

従って、横加速度偏差演算部１０３とＰＩ制御部１０４とにより横加速度のフィードバック演算部を構成している。 The lateral acceleration deviation calculating unit 103 feeds back and inputs the actual lateral acceleration G detected by the lateral acceleration sensor 34, and calculates a deviation ΔG (= G ^* −G) between the target lateral acceleration G ^* and the actual lateral acceleration G. To do. That is, the lateral acceleration deviation calculation unit 103 calculates a deviation ΔG between the target lateral acceleration G ^* and the actual lateral acceleration G that changes due to the influence of a disturbance such as a lateral wind. The calculated deviation ΔG is input to the PI control unit 104. The PI control unit 104 calculates a turning angle feedback control value Δδ _fb by adding a proportional term proportional to the input deviation ΔG and an integral term obtained by integrating the deviation ΔG, as shown in Equation 5 below.

Accordingly, the lateral acceleration deviation computing unit 103 and the PI control unit 104 constitute a lateral acceleration feedback computing unit.

The feedforward control value δ _ff and the feedback control value Δδ _fb are input to the target turning angle calculation unit 105. The target turning angle calculation unit 105 adds the feedforward control value δ _ff and the feedback control value Δδ _fb to calculate the target turning angle δ ^* (= δ _ff + Δδ _fb ).

The steering ECU 36 further includes a turning angle deviation calculation unit 106, a target current calculation unit 107, a current deviation calculation unit 108, a PI control unit 109, and a PWM voltage generation unit 110. The target turning angle δ ^* calculated by the target turning angle calculation unit 105 is input to the turning angle deviation calculation unit 106. The turning angle deviation calculation unit 106 inputs a turning angle δ (hereinafter referred to as an actual turning angle δ) from the turning angle sensor 32, and a deviation Δδ between the target turning angle δ ^* and the actual turning angle δ. (= Δ ^* −δ) is calculated. The calculated deviation Δδ is input to the target current calculation unit 107.

The target current calculation unit 107 inputs a deviation Δδ between the target turning angle δ ^* and the actual turning angle δ, and calculates a target current i ^* proportional to the deviation Δδ. This target current i ^* is a target current value for energizing the electric motor 24. The target current i ^* is input to the current deviation calculation unit 108. The current deviation calculation unit 108 inputs the target current i ^* calculated by the target current calculation unit 107 and the actual current i flowing through the electric motor 24 detected by the current detector 38a, and the deviation Δi (= i) between the two. ^* -I) is calculated. The deviation Δi calculated by the current deviation calculation unit 108 is input to the PI control unit 109.

The PI control unit 109 calculates a target voltage v ^* for driving the electric motor 24 by adding a proportional term proportional to the inputted deviation Δi and an integral term obtained by integrating the deviation Δi. That is, the target voltage v ^* is calculated so that the deviation Δi becomes zero. The target voltage v ^* calculated by the PI control unit 109 is input to the PWM voltage generation unit 110. The PWM voltage generator 110 outputs a PWM control voltage signal corresponding to the target voltage v ^* to the drive circuit 38. The drive circuit 38 includes a switching element, and is, for example, an inverter circuit or an H bridge circuit. The drive circuit 38 turns on and off the switching element with a duty ratio corresponding to the PWM control voltage signal, and applies the target voltage v ^* to the electric motor 24. Accordingly, the left and right front wheels FW1 and FW2 are steered by the driving force of the electric motor 24.

  Next, reaction force control by the steering reaction force ECU 35 will be described. The steering reaction force ECU 35 includes a basic reaction force calculation unit 201 and an additional assist force calculation unit 202.

The basic reaction force calculation unit 201 inputs the target lateral acceleration G ^* calculated by the target lateral acceleration calculation unit 101 and the steering angle θ _MA detected by the steering angle sensor 31, and inputs the target basic steering reaction force torque Tz ^*. Calculate That is, the basic reaction force calculation unit 201 refers to the reference map shown in FIG. 4 stored in advance, and calculates the spring reaction force torque component Tzb based on the target lateral acceleration G ^* input from the target lateral acceleration calculation unit 101. calculate. Further, the basic reaction force calculation unit 201 refers to the reference map shown in FIG. 5 stored in advance, based on the steering angular velocity θ _MA ′ obtained by differentiating the steering angle θ _MA input from the steering angle sensor 31 with respect to time. The friction reaction force torque component Tzm is calculated. Further, the basic reaction force calculation unit 201 calculates a viscous reaction force torque component Tzn based on the steering angular velocity θ _MA ′ with reference to a reference map shown in FIG. 6 stored in advance. Then, the basic reaction force calculation unit 201 calculates the target basic steering reaction force torque Tz ^* by adding the calculated torque components Tzb, Tzm, and Tzn.

In the present embodiment, each torque component Tzb, Tzm, Tzn is calculated using the reference map, but changes according to the target lateral acceleration G ^* and the steering angular velocity θ _MA ′ instead of the reference map. A function defining spring reaction force torque component Tzb, friction reaction force torque component Tzm, and viscous reaction force torque component Tzn is stored, and each torque component Tzb, Tzm, Tzn is calculated using this function. Good. In the present embodiment, the spring reaction force torque component Tzb is calculated based on the target lateral acceleration G ^*. However, for example, the spring reaction force torque component Tzb may be obtained based on the steering angle θ _MA .

The additional assist force calculation unit 202 receives the deviation ΔG calculated by the lateral acceleration deviation calculation unit 103, and calculates a target additional assist torque Ta ^* . That is, the additional assist force calculation unit 202 calculates the target additional assist torque Ta ^* in accordance with the deviation ΔG occurring and the PI control unit 104 calculating the feedback control value Δδ _fb of the turning angle. The calculated target additional assist torque Ta ^* is a torque that assists (assists) the driver to turn the steering handle 11 in a direction against a disturbance such as a crosswind, and is a target basic steering reaction torque. T ^* is the reverse torque. The additional assist force calculation unit 201 corresponds to the support force calculation means of the present invention.

Specifically, the additional assist force calculation unit 202 calculates a target additional assist torque Ta ^* based on the deviation ΔG input from the lateral acceleration deviation calculation unit 103 with reference to a reference map shown in FIG. 7 stored in advance. To do. As for the magnitude of the target additional assist torque Ta ^* , if it is too large, the resistance feeling during the turning operation of the steering handle 11 by the target basic steering reaction torque Tz ^* is impaired, and the steering handle 11 is turned excessively. In order to facilitate the operation, for example, the magnitude may be set to the same level as the spring reaction force torque component Tzb that forms the target basic steering reaction torque Tz ^* . When the deviation ΔG is small, the target additional assist torque Ta ^* is calculated as “0”. Thus, in a situation where the deviation ΔG is small, as described above, the feedback control value Δδ _fb is calculated by the PI control unit 104 and the left and right front wheels FW1, FW2 are subjected to the active steering control, but the target additional assist torque Ta ^* Is calculated to be “0”. Therefore, in this case, the active steering is executed without changing the reaction force perceived by the driver via the steering wheel 11 as in the conventional case. Further, in this embodiment, the target additional assist torque Ta ^* is calculated using the reference map, but a function that defines the target additional assist torque Ta ^* that changes according to the deviation ΔG instead of the reference map is used. The target additional assist torque Ta ^* may be calculated using this function.

The steering reaction force ECU 35 includes a target reaction force calculation unit 203, a target current calculation unit 204, a current deviation calculation unit 205, a PI control unit 206, and a PWM voltage generation unit 207. The target basic steering reaction torque T ^* and the target additional assist torque Ta ^* are input to the target reaction force calculator 203. The target reaction force calculator 203 adds the target basic steering reaction force torque Tz ^* and the target additional assist torque Ta ^* to calculate the target reaction force torque Tt ^* (= Tz ^* + Ta ^* ). Then, the calculated target reaction force torque Tt ^* is input to the target current calculation unit 204. As described above, since the target additional assist torque Ta ^* is a torque in the opposite direction to the target basic steering reaction torque Tz ^* , the target reaction torque Tt ^* is substantially equal to the target basic steering torque. is calculated as the torque from the reaction torque Tz ^* by subtracting the target additional assist torque Ta ^*.

Target current calculation unit 204 inputs the target reaction torque Tt ^*, calculates the target current it ^* proportional thereto. This target current it ^* is a target current value for energizing the electric motor 13. The target current it ^* is input to the current deviation calculation unit 205. The current deviation calculation unit 205 inputs the target current it ^* calculated by the target current calculation unit 204 and the actual current i flowing through the electric motor 13 detected by the current detector 37a, and the deviation Δi (= it) between the two. ^* -I) is calculated. The deviation Δi calculated by the current deviation calculation unit 205 is input to the PI control unit 206.

The PI control unit 206 adds a proportional term proportional to the input deviation Δi and an integral term obtained by integrating the deviation Δi to calculate a target voltage v ^* for driving the electric motor 13. That is, the target voltage v ^* is calculated so that the deviation Δi becomes zero. The target voltage v ^* calculated by the PI control unit 206 is input to the PWM voltage generation unit 207. The PWM voltage generator 207 outputs a PWM control voltage signal corresponding to the target voltage v ^* to the drive circuit 37. Similarly to the drive circuit 38, the drive circuit 37 is composed of a switching element, and is, for example, an inverter circuit or an H-bridge circuit. The drive circuit 37 turns on and off the switching element with a duty ratio corresponding to the PWM control voltage signal, and applies the target voltage v ^* to the electric motor 13. Thus, torque corresponding to the target reaction force torque Tt ^* is applied to the steering handle 11 by the driving force of the electric motor 13.

Next, the effect when the target reaction force torque Tt ^* is applied as described above will be described with reference to FIGS. FIG. 8 shows a situation where a driver having standard driving technique and driving experience corrects the behavior of the vehicle in addition to active steering when the target additional assist torque Ta ^* is not applied. Specifically, FIG. 8A shows that only the target basic steering reaction torque Tz ^* (more specifically, the spring reaction force torque component Tzb of the target basic steering reaction torque Tz ^* ) is applied. FIG. 8B shows the actual lateral acceleration detected by the lateral acceleration sensor 34 with respect to the target lateral acceleration G ^* (that is, the change in the steering angle θ _MA of the steering handle 11 accompanying the turning operation by the driver). It shows that the acceleration G is changing. FIG. 8C shows the yaw rate generated in the vehicle in accordance with the turning operation of the steering handle 11 by the driver as shown in a circle in the situation where the target additional assist torque Ta ^* is not applied. It shows that the change is getting bigger.

That is, in this case, even if the steering ECU 36 automatically steers the left and right front wheels FW1, FW2 (active steering), the target additional assist torque Ta ^* is not applied, so the reaction force perceived by the driver There is no fluctuation due to active steering. For this reason, when the driver turns the steering handle 11 in response to a change in the behavior of the vehicle, the left and right front wheels FW1 are turned by turning the steering handle 11 of the driver with respect to the turning of the left and right front wheels FW1 and FW2 by active steering. , FW2 is excessively steered, and as a result, the driver turns the steering handle 11 too much and the change in the yaw rate is large.

On the other hand, FIG. 9 shows a situation in which a driver having a standard driving technique and driving experience corrects the behavior of the vehicle in addition to the active steering when the target additional assist torque Ta ^* is applied. It is measured. Specifically, FIG. 9A shows the target basic steering reaction torque Tz ^* (more specifically, the spring reaction force torque component Tzb of the target basic steering reaction torque Tz ^* ) and the target additional assist torque Ta ^*. FIG. 9B shows that the lateral acceleration sensor 34 corresponds to the target lateral acceleration G ^* (that is, the change in the steering angle θ _MA of the steering handle 11 accompanying the turning operation by the driver). It shows that the lateral acceleration G detected by is changing. In this case, the change in the lateral acceleration G detected by the lateral acceleration sensor 34 is somewhat smaller than in FIG. FIG. 9C shows the rotation of the steering wheel 11 by the driver as compared with FIG. 8C, particularly in a circumstance where the target additional assist torque Ta ^* is applied. It shows that the change in the yaw rate generated in the vehicle with the operation is clearly reduced.

That is, in this case, when the steering ECU 36 actively steers the left and right front wheels FW1 and FW2, the target additional assist torque Ta ^* is applied, so that the reaction force perceived by the driver varies with the active steer. Arise. As a result, the driver can turn the steering handle 11 in response to a change in vehicle behavior while recognizing the change in the reaction force, so that the driver can steer the left and right front wheels FW1 and FW2 by active steering. The steering of the left and right front wheels FW1, FW2 due to the turning operation of the handle 11 is appropriately added, and as a result, the change in the yaw rate is reduced.

Thus, according to the first embodiment, when active steering is performed, the target additional assist torque Ta ^* can be applied to the steering handle 11 in accordance with the turning operation. Thus, the driver can turn the steering handle 11 while perceiving the applied target additional assist torque Ta ^* , in other words, while perceiving an appropriate variation of the reaction force. Therefore, even when the steering handle 11 is turned by itself in order to correct the behavior of the vehicle in addition to the active steering that is automatically executed, it is difficult to feel a sense of incongruity with a change in the behavior of the vehicle.

In addition, since the target additional assist torque Ta ^* can be applied to the steering handle 11, it is possible to prompt the driver to rotate the steering handle 11 in a direction that appropriately resists disturbance. As a result, the driver can quickly (naturally) rotate the steering handle 11, and can quickly correct the behavior of the vehicle.

b. Second Embodiment In the first embodiment described above, the left and right front wheels FW1, FW2 are actively steered according to the change in the actual lateral acceleration G accompanying the input of disturbance, and the target additional assist torque Ta * according to the turning operation. It carried out to give. In this case, drivers who have excellent driving skills and abundant driving experience and are familiar with driving (so-called skill drivers) respond quickly to disturbance inputs, and add targets as deviation ΔG occurs. If the assist torque Ta ^* is simply applied, the steering handle 11 tends to rotate excessively. This will be described with reference to FIGS.

FIG. 10 shows a situation where the skill driver corrects the behavior of the vehicle in addition to the active steering when the target additional assist torque Ta ^* is not applied. Specifically, FIG. 10A shows that only the target basic steering reaction torque Tz ^* (more specifically, the spring reaction force torque component Tzb of the target basic steering reaction torque Tz ^* ) is applied. FIG. 10B shows the lateral acceleration detected by the lateral acceleration sensor 34 with respect to the target lateral acceleration G ^* (that is, the change in the steering angle θ _MA of the steering handle 11 accompanying the turning operation by the skill driver). FIG. 10 (c) shows a change in the yaw rate generated in the vehicle as the skill driver turns the steering wheel 11 in a situation where the target additional assist torque Ta ^* is not applied. Is shown.

On the other hand, FIG. 11 shows that the skill driver is added to the active steering when the target additional assist torque Ta ^* is applied with the occurrence of the deviation ΔG as described in the first embodiment. This is a measurement of the situation in which the behavior of the vehicle is corrected. Specifically, FIG. 11A shows the target basic steering reaction torque Tz ^* (more specifically, the spring reaction force torque component Tzb of the target basic steering reaction torque Tz ^* ) and the target additional assist torque Ta ^*. 11 (b) shows that the lateral acceleration sensor 34 corresponds to the target lateral acceleration G ^* (that is, the change in the steering angle θ _MA of the steering handle 11 accompanying the turning operation by the skill driver). It shows that the lateral acceleration G detected by is changing. FIG. 11C shows a skill driver in a situation where the target additional assist torque Ta ^* is applied in accordance with the occurrence of the deviation ΔG, as compared with FIG. This shows that the change in the yaw rate generated in the vehicle with the turning operation of the steering handle 11 by the vehicle is larger.

That is, in this case, the target additional assist torque Ta ^* is always applied as the deviation ΔG occurs. For this reason, in a skill driver having a quick response, the steering handle 11 is excessively rotated by the target additional assist torque Ta ^* , and as a result, the yaw rate changes greatly. Therefore, in the second embodiment, the target additional assist torque Ta ^* is not applied in the low frequency range of the deviation ΔG that the skill driver can deal with the input of the disturbance, and the target corresponding to the high frequency range of the deviation ΔG. Additional assist torque Ta ^* is applied. Hereinafter, although this 2nd Embodiment is described in detail, the same code | symbol is attached | subjected to the same part as the said 1st Embodiment, and the detailed description is abbreviate | omitted.

In the second embodiment, as shown in FIG. 12, the steering reaction force ECU 35 includes a high-pass filter processing unit 208 (hereinafter simply referred to as an HPF processing unit 208), as compared to the first embodiment. It is different in point. The HPF processing unit 208 passes only a signal having a frequency equal to or higher than a preset frequency out of the deviation ΔG output from the lateral acceleration deviation calculation unit 103 and inputs the signal to the additional assist force calculation unit 202. As a result, the additional assist force calculation unit 202 calculates the target additional assist torque Ta ^* based on the deviation ΔG having only a high-frequency component, as in the first embodiment. As a result, the additional assist force calculation unit 202 does not calculate the target additional assist torque Ta ^* based on the deviation ΔG having a low-frequency component that can react to the disturbance input by the skill driver, and reacts even for a skill driver. A target additional assist torque Ta ^* based on the deviation ΔG having an unobtainable high frequency component is calculated.

The target reaction force calculation unit 203 is calculated based on the target basic steering reaction force torque Tz ^* calculated by the basic reaction force calculation unit 201 and the deviation ΔG having a high frequency component, as in the first embodiment. The target additional assist torque Ta ^* is added (more specifically, the target additional assist torque Ta ^* in the reverse direction is subtracted from the target basic steering reaction torque Tz ^* ) to calculate the target reaction torque Tt ^* . As described above, when the target reaction force calculation unit 203 calculates the target reaction force torque Tt ^* , the target current calculation unit 204, the current deviation calculation unit 205, the PI control unit 206, and the PWM voltage generation are performed as in the first embodiment. The electric motor 13 is drive-controlled by the unit 207, and a torque corresponding to the target reaction force torque Tt ^* is applied to the steering handle 11.

Next, the effect when the target reaction force torque Tt ^* is applied as described above will be described with reference to FIG. FIG. 13 shows a situation where the skill driver corrects the behavior of the vehicle in addition to the active steering when the target additional assist torque Ta ^* is applied based on the deviation ΔG having only a high-frequency component. . More specifically, FIG. 13A shows the target basic steering reaction torque Tz ^* (more specifically, the spring reaction force torque component Tzb of the target basic steering reaction torque Tz ^* ) and the target additional assist torque Ta ^*. FIG. 13B shows that the lateral acceleration sensor 34 corresponds to the target lateral acceleration G ^* (that is, the change in the steering angle θ _MA of the steering handle 11 accompanying the turning operation by the driver). It shows that the lateral acceleration G detected by is changing. In this case, the change in the lateral acceleration G detected by the lateral acceleration sensor 34 is smaller than that in FIG. FIG. 13C shows a situation where the target additional assist torque Ta ^* is applied based on the deviation ΔG having only a high frequency component, as compared with FIG. This shows that the change in the yaw rate generated in the vehicle due to the turning operation of the steering handle 11 by the driver is greatly reduced.

That is, in this case, when the steering ECU 36 actively steers the left and right front wheels FW1 and FW2, the target additional assist torque Ta ^* is applied based on the deviation ΔG having only a high frequency component, so that the skill driver reacts. the target additional assist torque Ta ^* is not granted for the low-frequency component that can correspond, for high-frequency components can not correspond to react even skill drivers target additional assist torque Ta ^* is given by. As a result, the skill driver is encouraged to respond quickly to the disturbance by applying the target additional assist torque Ta ^* accompanying active steering based on the deviation ΔG having only a high-frequency component, while his intention (reaction) When the steering handle 11 is turned based on this, an appropriate reaction force can be perceived. As a result, the steering of the left and right front wheels FW1 and FW2 by the turning operation of the steering handle 11 of the skill driver is appropriately added to the steering of the left and right front wheels FW1 and FW2 by active steering, and as a result, the yaw rate changes Is getting smaller.

As described above, according to the second embodiment, when active steering is performed, the target additional assist torque Ta ^* based on the deviation ΔG having only a high-frequency component is applied to the steering handle 11 in accordance with the steering operation. Can do. As a result, the skill driver can turn the steering handle 11 while perceiving the applied target additional assist torque Ta ^* , so that the skill driver turns the steering handle 11 himself to correct the behavior of the vehicle. Even in this case, it becomes difficult to feel uncomfortable with changes in the behavior of the vehicle.

Further, the target additional assist torque Ta ^* calculated based on the deviation ΔG having only a high frequency component is applied to the steering handle 11, in other words, the target additional assist torque Ta ^* based on the deviation ΔG having a low frequency component is applied to the steering handle. 11, it is possible to prompt the skill driver to rotate the steering handle 11 in a direction appropriately resisting disturbance. Thereby, the skill driver can rotate the steering handle 11 more quickly (naturally), and can quickly correct the behavior of the vehicle.

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

For example, in the first and second embodiments, the target lateral acceleration calculation unit 101 calculates the target lateral acceleration G ^* , and the lateral acceleration deviation calculation unit 103 detects the actual lateral acceleration G detected by the lateral acceleration sensor 34 and the target. The deviation ΔG of the lateral acceleration G ^* was calculated, and the additional assist force calculation unit 202 calculated the target additional assist torque Ta ^* corresponding to the deviation ΔG. In this case, since the yaw rate γ generated in the vehicle is expressed by γ = G / V using the lateral acceleration G and the vehicle speed V, the yaw rate generated in the vehicle is used instead of using the lateral acceleration G generated in the vehicle. It is also possible to implement so that the additional assist force calculation unit 202 calculates the target additional assist torque Ta ^* using γ.

In this case, the electric control device 30 is changed to include a yaw rate sensor 39 that detects an actual yaw rate γ generated in the vehicle, as indicated by a broken line in FIG. Instead of including the 101 and the lateral acceleration deviation calculating unit 103, the target yaw rate calculating unit and the yaw rate deviation calculating unit may be modified. The target yaw rate calculation unit calculates the target yaw rate γ ^* in the same manner as the target lateral acceleration calculation unit 101, and the yaw rate deviation calculation unit in the same manner as the lateral acceleration deviation calculation unit 103 detects the actual yaw rate sensor 39. A deviation Δγ between the yaw rate γ and the target yaw rate γ ^* is calculated. As a result, the additional assist force calculation unit 202 calculates the target additional assist torque Ta ^* corresponding to the deviation Δγ in the same manner as in the first and second embodiments, so that the same as in the first and second embodiments. Can be expected.

  In the first and second embodiments, a steering-by-wire steering device is employed. However, the present invention can also be applied to a gear ratio variable steering device that can freely adjust the steering gear ratio. Even in this case, the same effect as in the first and second embodiments can be expected.

  DESCRIPTION OF SYMBOLS 10 ... Steering operation device, 11 ... Steering handle, 20 ... Steering device, 24 ... Electric motor for steering, 30 ... Electric control device, 31 ... Steering angle sensor, 32 ... Steering angle sensor, 33 ... Vehicle speed sensor, 34 DESCRIPTION OF SYMBOLS ... Lateral acceleration sensor, 35 ... Steering reaction force ECU, 36 ... Steering ECU, 39 ... Yaw rate sensor, 101 ... Target lateral acceleration calculating part, 102 ... Feed forward calculating part, 103 ... Lateral acceleration deviation calculating part, 104 ... PI control unit 105 ... target turning angle calculation unit 106 ... turning angle deviation calculation unit 201 ... basic reaction force calculation unit 202 ... additional assist force calculation unit 208 ... HPF processing unit

Claims (3)

Changes due to a steering handle that is operated to steer the vehicle, a reaction force actuator that applies a reaction force to the operation of the steering handle, a steering actuator that steers wheels, and a disturbance applied in the lateral direction of the vehicle The physical quantity detection means for detecting the actual physical quantity generated in the vehicle body, the target physical quantity calculation means for calculating the target physical quantity of the physical quantity generated in the vehicle body in response to the operation of the steering handle, and the target physical quantity calculation means A command value setting means for setting a command value according to the target physical quantity, a command value set by the command value setting means, and a deviation between the detected actual physical quantity and the calculated target physical quantity. In a vehicle steering apparatus comprising a steering control means for driving the actuator to steer the wheel,
Based on the deviation between the detected actual physical quantity and the calculated target physical quantity, a support force calculating means for calculating a force that supports operating the steering wheel in a direction against a disturbance applied in a lateral direction of the vehicle. When,
And a reaction force control means for driving the reaction force actuator based on a target reaction force obtained by adding the calculated assisting force to a reaction force applied to the operation of the steering wheel. Vehicle steering device. The vehicle steering apparatus according to claim 1, further comprising:
Of the deviation between the detected actual physical quantity and the calculated target physical quantity, a filter that allows only a frequency component higher than a predetermined frequency to pass is provided,
The support power calculation means includes:
A vehicle steering apparatus, wherein the assisting force is calculated based on a deviation having a high frequency component that has passed through the filter. In the vehicle steering apparatus according to claim 1 or 2,
The physical quantity is
A vehicle steering apparatus characterized by a lateral acceleration generated in the vehicle width direction of the vehicle body or a yaw rate generated around the center of gravity of the vehicle body.

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