JP2006248308A - Steering device for vehicle - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a steering device for a vehicle which reduces the operation burden of a steering method by an azimuth angle feedback control at the time of a stationary turning or at the time of a low-speed traveling of the vehicle, and enables an easy steering by a driver to be realized. <P>SOLUTION: This steering device for the vehicle is equipped with an operation element 11 which is operated by the driver, an operation amount sensing section 13 which detects the operation amount of the operation element 11, a steering actuator 19 which changes the direction of tires, and a controlling device 22 which drives the steering actuator 19 in response to the operation amount of the operation element 11. In the steering device for the vehicle, the controlling device 22 is equipped with a controlling section 30 for the setting of a target azimuth angle, a controlling section 31 for the setting of a target tire angle, and a switching section 32. In this case, the control section 30 for the setting of the target azimuth angle sets the target azimuth angle in response to the operation amount, and drives the steering actuator from the target azimuth angle. The controlling section 31 for the setting of the target tire angle drives the steering actuator from the target tire angle. The switching section 32 switches the controlling sections to either one of the control section 30 for the setting of the target azimuth angle and the controlling section 31 for the setting of the target tire angle depending on the traveling conditions of the vehicle. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a vehicle steering apparatus, and more particularly to a steer-by-wire (SBW) type vehicle steering apparatus.

  As a vehicle steering apparatus in which the traveling azimuth of a vehicle is controlled by a steering angle of an operation element such as a steering wheel, that is, an azimuth indicating angle, an apparatus described in Patent Document 1 is known. Furthermore, an apparatus described in Patent Document 2 is known as a vehicle steering apparatus that stably and stably controls the direction of the vehicle with respect to the operation of the steering wheel.

  The steering apparatus described in Patent Document 1 is an apparatus having power steering means for an actuator to steer a steered wheel. This steering device includes steering instruction means for instructing a traveling azimuth angle of a vehicle based on a predetermined absolute azimuth by a driver's operation, and a traveling direction detection for detecting a vehicle traveling azimuth angle based on a predetermined absolute azimuth. Means. The control means controls the power steering means so that the deviation between the traveling azimuth instructed by the steering instruction means and the vehicle traveling azimuth detected by the traveling direction detection means becomes zero.

  Similar to the steering apparatus described in Patent Document 1, the steering apparatus described in Patent Document 2 is a steering instruction means, a traveling direction detection means, and a traveling direction change amount and a traveling direction input from the steering instruction means. Control means for controlling the steering mechanism so that the azimuth angle deviation from the amount of change in the vehicle traveling direction detected by the detection means becomes zero. The control means includes steering angle designation means for outputting a signal related to the steering angle based on the azimuth angle deviation, and the steering angle designation means is configured to reduce the steering angle output as the vehicle speed increases. . As a result, the vehicle steering apparatus is further stable in handling.

  The conventional techniques described in Patent Document 1 and Patent Document 2 described above are a vehicle traveling azimuth angle based on a predetermined absolute azimuth or a predetermined absolute azimuth with respect to a driver's steering angle (azimuth direction angle). The steering means is controlled so that the deviation from the direction becomes zero. Hereinafter, the steering device shown in Patent Literature 1 and Patent Literature 2 will be referred to as “steering device for azimuth feedback control”. In addition, a steering device in which a tire angle is determined based on a driver's steering angle, which is currently widely used, is referred to as a “tire angle control steering device” in the present specification.

JP-A-1-233170 JP-A-6-92250

  In the steering device of azimuth angle feedback control, when the azimuth angle after the course change does not change like a lane change, the steering wheel steering angle returns to the original. However, when the azimuth angle changes as in the case of a right or left turn, the steering angle of the steering wheel rotates by an angle corresponding to the azimuth angle and remains there. As long as the steering angle of the steering wheel is kept constant, lateral displacement will occur even if any disturbance is applied to the vehicle, but the azimuth angle will not change and the course can be maintained, greatly reducing the driver's steering burden. can do.

  On the other hand, in a steering device for tire angle control, the steering wheel angle may be kept constant when turning with a constant radius. However, in a steering device for azimuth angle feedback control, it is necessary to constantly increase the steering wheel steering angle. Therefore, for drivers who are accustomed to steering a steering device for tire angle control, which is the current steering system, there is a great difference from the previous steering method in such a continuous circular turn, so the steering of azimuth feedback control It takes time to get used to the method and the operation burden increases.

  In addition, in the steering device of azimuth feedback control, it is necessary to keep turning the steering wheel in order to maintain the angle of the steered wheels, so a large angle of steered wheels is required when entering the garage or starting from parallel parking. In this case, the operation burden increases compared to the conventional control method.

  In view of the above problems, an object of the present invention is to reduce the operational burden of the steering method of the azimuth feedback control when the vehicle is traveling at a steady turn or at low speed, and allows the driver to easily perform the steering. Is to provide.

  In order to achieve the above object, a vehicle steering apparatus according to the present invention is configured as follows.

  A first vehicle steering apparatus (corresponding to claim 1) includes an operation element that is operated by a driver, an operation amount detection unit that detects an operation amount of the operation element, a steering actuator that changes a tire direction, And a control device that drives the steering actuator according to the operation amount of the operation element. The control device sets a target azimuth angle according to the operation amount, and steers based on the target azimuth angle. A target azimuth angle setting control unit for driving the actuator, a target tire angle setting control unit for setting the target tire angle according to the operation amount, and driving the steered actuator based on the target tire angle, and a running condition of the vehicle And a switching unit that switches to one of the target azimuth angle setting control unit and the target tire angle setting control unit.

  According to said structure, according to the driving conditions of a vehicle, it switches to either a target azimuth angle setting control part or a target tire angle setting control part by the switching part. Thereby, the operation burden of the steering method of the azimuth feedback control can be reduced during steady turning of the vehicle or at low speed, and the driver can easily perform the steering.

  In the second vehicle steering device (corresponding to claim 2), in the above configuration, preferably, the switching unit is configured so that when the vehicle is in a turning state over a predetermined time, the target azimuth angle setting control unit is connected to the target tire. It is characterized by switching to a corner setting control unit.

  In the third vehicle steering device (corresponding to claim 3), in the above configuration, the switching unit preferably sets the target azimuth angle from the target tire angle setting control unit when the steering torque of the operation element becomes zero. It is characterized by switching to the control unit.

  In the fourth vehicle steering apparatus (corresponding to claim 4), in the above configuration, the switching unit preferably switches from the target azimuth angle setting control unit to the target tire angle setting control unit at a low speed or at the start. It is characterized by.

  A fifth vehicle steering apparatus (corresponding to claim 5) includes an operation element that is operated by a driver, an operation amount detection unit that detects an operation amount of the operation element, a steering actuator that changes a tire direction, A vehicle traveling direction detection unit that detects a vehicle traveling direction, and a control device that drives a steered actuator by a target azimuth angle according to an operation amount of an operation element and an azimuth angle feedback control based on the vehicle traveling direction. In the steering device, the control device calculates a vehicle azimuth based on a vehicle traveling direction detected by a vehicle traveling direction detection unit and a target azimuth setting unit that sets a target azimuth according to an operation amount. An azimuth gain unit that outputs a multiplication azimuth by multiplying the vehicle azimuth output from the azimuth calculation unit by a gain coefficient, and a steering actuator based on a difference between the target azimuth and the multiplication azimuth. Comprising a driving unit for driving the over motor, and a gain controller for varying the gain factor depending on the running condition of the vehicle, characterized by.

  In the sixth vehicle steering device (corresponding to claim 6), in the above configuration, the gain variable unit preferably performs control equivalent to tire angle control by setting the gain coefficient of the azimuth gain unit to 0. The gain coefficient is set to a value other than 0 and the azimuth feedback control is executed.

  According to the present invention, the tire angle by the target tire angle setting control unit at the time of steady circle turning, in addition to the reduction of the operation load that eliminates the need to return the steering wheel after changing the course by the azimuth angle feedback control by the target azimuth angle setting control unit. Similar to the steering method currently widely used by control, it is only necessary to keep the steering wheel constant, so that the operation burden at the time of steady circle turning does not increase. In addition, this reduces the magnitude of the difference between steering wheel operation of the steering device for azimuth feedback control and steering wheel operation of the steering device for tire angle control. Even a driver who is used to the method can easily control the azimuth feedback control with little discomfort.

  In addition, according to the present invention, it is not necessary to keep turning the steering wheel even when traveling at an extremely low speed such as when entering a garage or when starting from parallel parking, and a steering device for tire angle control that is currently widely used. It is possible to turn by holding the steering wheel in the same manner as the steering method. Further, as described above, since the magnitude of the difference between the steering operation of the steering device of the azimuth feedback control and the steering method of the steering device of the tire angle control is reduced, the tire angle control that is currently widely used. Even a driver who is accustomed to the steering method of the steering apparatus can easily control the azimuth feedback control with little discomfort.

  DESCRIPTION OF EMBODIMENTS Preferred embodiments (examples) of the present invention will be described below with reference to the accompanying drawings.

  FIG. 1 is a schematic structural diagram of a vehicle steering apparatus according to a first embodiment of the present invention. The vehicle steering apparatus 10 arbitrarily controls the turning angle (synonymous with the steering angle) of the front tire 21 that is a steered wheel in response to a steering input of an operation element 11 such as a steering wheel (hereinafter referred to as “handle 11”). This is an electronically controlled vehicle steering device.

  The steering wheel 11 is used to input an operation amount for changing the azimuth angle or tire angle of the vehicle when operated by the driver. For example, when the control device (ECU) 22 is connected to the target azimuth angle setting control unit 30 by the control switching unit 32 described in FIG. 2, the driver 11 rotates the handle 11 to rotate it. An operation amount for changing the azimuth angle according to the angle is input. Further, when the control device 22 is connected to the target tire angle setting control unit 31 by the control switching unit 32 (see FIG. 2), the driver rotates the steering wheel so that the tire angle is determined by the rotated angle. An operation amount for changing the value is input.

  The operation amount detection unit 13 detects the operation amount input by the driver from the handle 11 and inputs the handle steering angle θ to the control device 22. That is, a signal 13s related to the steering angle θ of the steering wheel 11 from a predetermined position of the steering wheel 11 is supplied to the control device 22 by detecting the rotation of the steering shaft 12 using a rotary encoder or the like. When the control device 22 shown in FIG. 2 is connected to the target azimuth angle setting control unit 30 by the control switching unit 32, the operation amount becomes the azimuth instruction angle. The azimuth indicating angle represents an azimuth angle based on this azimuth with the above-mentioned predetermined position as an absolute azimuth such as north or the current traveling azimuth of the vehicle. Further, when the control device 22 is connected to the target tire angle setting control unit 31 by the control switching unit 32 (see FIG. 2), the operation amount detection unit 13 is used to change the tire angle. Amount.

  The steering reaction force generation actuator 14 is controlled by the control device 22 and applies a reaction force to the handle 11. The steering reaction force generation actuator 14 includes a gear mechanism (not shown) and is supplied from the control device 22. A steering reaction force corresponding to the magnitude of the motor current 14s is applied.

  The steering torque sensor 15 detects the steering torque input from the handle 11 and outputs a steering torque signal 15 s to the control device 22.

  The vehicle speed sensor 16 supplies a signal 16 s related to the vehicle speed V to the control device 22. The traveling direction detection unit 17 is configured using a yaw rate gyro, a navigation system, or the like, and inputs a signal 17 s related to the traveling direction to the control device 22.

  The vehicle behavior sensor 18 inputs a signal 18 s related to a vehicle behavior state such as a yaw rate, a lateral acceleration, and a vehicle speed to the control device 22.

  The rudder angle generator 19 is a rudder angle actuator, and is configured to steer the front tire 21 based on a steering drive signal 39 s output from the control device 22.

  The steered angle sensor 20 detects an actual steered angle and outputs a signal 20 s related to the actual steered angle to the control device 22.

  The control device 22 includes a signal 13s related to the steering wheel steering angle θ, a signal 17s related to the traveling direction, a signal 16s related to the vehicle speed V, a signal 15s related to the steering torque, a signal 20s related to the actual steering angle, and a signal related to the vehicle behavior state. 18s is input to control the polarity and current value of the motor current to give a steering reaction force to the steering wheel 11, and as shown in FIG. 2, the target azimuth angle setting control unit 30 and the target tire angle setting control unit 31 are provided. And switching. When the switching unit 45 is connected to the target azimuth angle setting control unit 30, the control device 22 drives the rudder angle generation unit 19 so as to control the azimuth angle of the vehicle corresponding to the steering wheel steering angle θ. . Further, when the switching unit 45 is connected to the target tire angle setting control unit 31, the steering angle generation unit 19 is driven so as to control the tire angle corresponding to the steering wheel steering angle θ.

  FIG. 2 is a block configuration diagram of a control device in the vehicle steering device of the present embodiment. The control device 22 includes a target azimuth angle setting control unit 30, a target tire angle setting control unit 31, a control switching unit 32, and a steering reaction force control unit 33. The target azimuth setting controller 30 sets a target azimuth according to the amount of operation of the handle 11, and drives the rudder angle generator 19 based on the target azimuth. The target azimuth setting controller 30 performs azimuth feedback control. The target tire angle setting control unit 31 sets a target tire angle according to the operation amount of the handle 11, and drives the rudder angle generation unit 19 based on the target tire angle. The target tire angle setting control unit 31 performs conventional tire angle control. The control switching unit 32 controls the target azimuth setting based on the signals from the switch 49, the steering angle sensor 48, the steering torque sensor 15, the turning angle sensor 20, the vehicle behavior sensor 18, and the vehicle speed sensor 16. Switching between the unit 30 and the target tire angle setting control unit 31 is performed. Note that the operation amount detection unit 13 may be used instead of the steering angle sensor 48.

  The target azimuth angle setting control unit 30 includes a target azimuth angle setting unit 35, a deviation calculating unit 36, an actual rudder angle specifying unit 37, an actual rudder angle control unit 38, an actual rudder angle driving unit 39, an azimuth angle calculating unit 40, and an azimuth. An angular gain unit 41 is included.

  The target azimuth angle setting unit 35 outputs a signal related to the target azimuth angle based on the signal related to the steering wheel steering angle θ detected by the operation amount detection unit 13, and sets the ratio k1 between the steering wheel steering angle and the target azimuth angle. It is configured so that it can be set arbitrarily. When the ratio k1 is set to 1.0, the steering wheel steering angle and the target azimuth angle are equal. That is, when the steering wheel 11 is rotated 180 degrees, the target azimuth is changed to the south direction if the current traveling direction of the vehicle is the north direction. When the ratio k1 is set to 0.5, when the handle 11 is rotated 180 degrees to the right, the target azimuth is 90 degrees to the right with respect to the traveling direction of the vehicle (for example, from north to east). Change.

  The azimuth calculation unit 40 outputs a signal related to the current traveling direction of the vehicle obtained based on the signal output from the traveling direction detection unit 17. The azimuth gain unit 41 outputs a value obtained by multiplying a signal related to the traveling direction by an arbitrarily set ratio k2 to the deviation calculation unit 36.

  The deviation calculating unit 36 obtains an azimuth deviation E between a signal related to the target azimuth output from the target azimuth setting unit 35 and a signal obtained by multiplying the signal related to the traveling azimuth by the ratio k2 and relates to the azimuth deviation. The signal is supplied to the actual steering angle specifying unit 37.

  The actual rudder angle designating unit 37 and the actual rudder angle control unit 38 constitute an actual rudder angle calculation unit. The actual steering angle calculation unit outputs a signal related to the steering angle based on the signal related to the azimuth angle deviation and the signal related to the vehicle speed V detected by the vehicle speed detection unit 16. The actual rudder angle calculation unit is configured by a conversion table that stores a rudder angle set in advance corresponding to each azimuth angle deviation and each vehicle speed V using, for example, a ROM. The actual rudder angle calculation unit may be configured to calculate and output the rudder angle based on a function equation or the like registered in advance. Further, when the changeover switch 46 is connected to the contact B, a zero output command signal is received from the changeover switch 46, and at that time, the output from the actual steering angle designation unit 37 becomes zero.

  The actual rudder angle drive unit 39 is configured to output a steering drive signal for driving the rudder angle generation unit 19 based on a signal related to the steering target value output from the actual rudder angle calculation unit. When the rudder angle generator 19 includes a gear mechanism and the like and controls the steering angle of the vehicle based on the polarity and current value of the motor current supplied to the DC motor, the actual rudder angle drive unit 39 sets the steering target value to the steering target value. Correspondingly, a preset motor current is supplied with a preset polarity. When the rudder angle generating unit 19 is configured using a pulse motor or the like, the actual rudder angle driving unit 39 is configured to supply a necessary number of forward rotation pulses or reverse rotation pulses. The direction of the vehicle 1 is controlled by the rudder angle generator 19, the traveling direction is detected based on the yaw rate γ, and the vehicle azimuth angle (yaw angle: ψ) is obtained by integrating the yaw rate γ (block 2). It is determined.

  The steering reaction force control unit 33 includes a steering reaction force setting unit 42 and a steering reaction force actuator driving unit 43.

  The steering reaction force setting unit 42 relates to the reaction force torque target value T based on the signal output from the actual steering angle control unit 38, the signal E output from the deviation calculation unit 36, and the signal related to the vehicle speed V. Output a signal. The steering reaction force setting unit 42 is composed of, for example, a ROM or the like, and includes a conversion table that stores preset reaction force torque target values corresponding to each actual steering angle δ, each deviation, and each vehicle speed V. . The steering reaction force setting unit 43 may be configured to calculate and output a reaction force torque target value based on a function equation registered in advance.

  The steering reaction force actuator drive unit 43 outputs a steering reaction force generation actuator drive signal for driving the steering reaction force generation actuator 14 based on the reaction force torque target value output from the steering reaction force setting unit 42.

  The target tire angle setting control unit 31 includes a target tire angle setting unit 44 and an actual steering angle driving unit 39. The actual rudder angle drive unit 39 is shared with the target azimuth angle setting control unit 30. Therefore, explanation is omitted.

  The target tire angle setting unit 44 outputs a signal related to the tire angle based on the signal related to the steering wheel steering angle θ and the signal related to the vehicle speed V detected by the vehicle speed detection unit 16. The target tire angle setting unit is composed of, for example, a ROM or the like, and includes a conversion table storing tire angles set in advance corresponding to the steering wheel steering angles θ and the vehicle speeds V. The target tire angle setting unit may be configured to calculate and output a tire angle based on a function equation registered in advance.

  The control switching unit 32 includes a switching unit 45, a changeover switch 46, and a control switching area setting unit 47. The control switching area setting unit 47 receives detection values from the steering angle sensor 48, the steering torque sensor 15, the turning angle sensor 20, the vehicle behavior sensor 18, and the vehicle speed sensor 16, and based on the input values, When switching to the target azimuth angle setting control unit 30, a target azimuth angle setting control unit switching signal is sent to the switching unit 45, and when switching to the target tire angle setting control unit 31, the target tire angle setting control is sent to the switching unit 45. Send a part change signal. The control switching area setting unit 47 stores a map of a target azimuth angle setting control unit or a target tire angle setting control unit corresponding to the steering angle, the steering torque, the turning angle, the vehicle behavior, and the vehicle speed. For example, when it is determined that the vehicle is making a circular turn based on the value from each sensor, or when it is detected that the vehicle is running at low speed or starting, a signal for switching to the target tire angle setting control unit 31 is provided. send. For example, the tire angle control operation can be performed by connecting to the target tire angle setting control unit 31 at all times at low speeds, for example, at low speeds from 0 km / h to 5 km / h, based on information from the vehicle speed sensor 16. . It is also possible to detect the steering state from information such as steering torque and connect to the target azimuth angle setting control unit 30 even at low speeds to utilize the azimuth feedback control.

  The switching unit 45 receives the signal from the switch 49 and the signal from the control switching region setting unit 47 and outputs a switching signal to the selector switch 46. The changeover switch 46 is connected to the contact A when switching to the target azimuth angle setting control unit 30 according to the signal from the switching unit 45, and is connected to the contact B when switching to the target tire angle setting control unit 31. When the changeover switch 46 is connected to the contact point B, a zero command signal is sent to the actual steering angle designation unit 37 and the signal output from the actual steering angle designation unit 37 becomes zero.

  By using the switch 49, in addition to automatically switching between the steering method of the azimuth feedback control by the control unit 30 for target azimuth setting and the steering method of the tire angle control by the control unit 31 for target tire angle setting, the driver's intention Thus, it is possible to switch both of them, and to improve the feeling at the time of switching.

FIG. 3 shows a case where the switching unit 45 switches between the target azimuth angle setting control unit (azimuth angle feedback control) 30 and the target tire angle setting control unit (tire angle control) 31 in the steady circular turning state of the present embodiment. 6 is a graph showing temporal changes in the steering angle θ, steering torque T _θ , steering angle δ, yaw rate γ, and yaw angle ψ. 3A shows the time change of the steering angle θ, FIG. 3B shows the time change of the steering torque T _θ , and FIG. 3C shows the time change of the steering angle δ and the yaw rate γ. FIG. 3D shows the time change of the yaw angle ψ, and FIG. 3E shows the time change of the difference between the steering angle and the yaw angle (θ−ψ). A solid line in each graph indicates a time change of each value in the present embodiment, and a dotted line indicates azimuth feedback control without switching from the target azimuth setting controller 30 to the target tire angle setting controller 31. The output when only is shown for reference. In this embodiment, the state in which the steering torque _Tθ is continuously output for a certain period of time is regarded as a steady circular turning state, and the azimuth angle feedback control is switched to the conventional tire angle control. As shown in FIG. 3, steering starts from time T _A and a steady circular turning state starts from time T _B. It determines the steady circular turn when that state continues until time T _C, switched to the conventional tire angle control, then, reducing the steering angle δ with decreasing steering torque T _theta between the time T _D of T _E, T _theta again at time T _E of zero, switching the azimuth angle feedback control from the tire angle control. As for the other outputs, the yaw rate γ and the yaw angle ψ, the same results as those obtained when the azimuth feedback control is performed as shown in FIGS. 3C and 3D are obtained. As described above, according to this embodiment, the steering wheel steering angle θ is kept equal to the steering of the conventional tire angle control, thereby enabling steady circular turning. In the present embodiment, the switching based on the steering torque is shown. However, it is possible to perform the switching in consideration of other vehicle state information such as the vehicle speed, the yaw rate, and the lateral acceleration, and the turning state without using the steering torque. This can also be achieved by detecting and switching.

  Next, a vehicle steering apparatus according to a second embodiment of the present invention will be described with reference to the block diagram of FIG. As shown in FIG. 4, the control device (ECU) 50 in the second embodiment is provided with an azimuth feedback control failure diagnosis unit 51 instead of the control switching region setting unit 47 of the control device 22 of the first embodiment. The point is different. Then, a failure is determined based on the vehicle speed signal, the signal from the actual steering angle control unit 38, and the signals from the steering angle sensor 48, the steering torque sensor 15, the steering angle sensor 20, and the vehicle behavior sensor 18. That is, the target rudder angle obtained from the steering wheel steering angle and the steering torque, the control target turning angle set by the actual rudder angle control unit 38, and the actual rudder angle detected by the turning angle sensor 20 are compared with each other. Determine the failure. When a failure is determined, a switching signal to the switching unit 45 is sent to the target tire angle setting control unit, and a signal is sent to the switching switch 46 accordingly. The changeover switch 46 is switched from the contact A to the contact B, and is switched to the control by the target tire angle setting control unit 31. At this time, in a system having a mechanical backup mechanism described below, a command for clutch connection may be issued at the same time, the clutch mechanism may be connected, and mechanical connection may occur simultaneously. Other than that, the configuration is the same as that described in the first embodiment. Elements that are substantially the same as those described in the first embodiment are given the same reference numerals, and descriptions thereof are omitted.

  FIG. 5 shows an example of a steer-by-wire system configuration provided with a mechanical backup mechanism. This steer-by-wire system includes a mechanical clutch mechanism 73, and the clutch mechanism 73 is normally disconnected so that the angle of the steered wheels can be arbitrarily controlled with respect to the input amount of the steering wheel. When a system failure occurs, the clutch mechanism 73 is connected to enable conventional mechanical steering. The steering device 60 includes a steering shaft 62 coupled to the handle 61, an operation amount detection unit 63, a steering reaction force generation actuator 64, a steering torque sensor 65, a vehicle speed sensor 66, a traveling direction detection unit 67, A vehicle motion state detector 68, a steering angle generator 69, a turning angle sensor 70, a tire 71, and a control device (ECU) 72 are provided. The steering shaft 62 is rotatably supported by a vehicle body (not shown).

  According to the vehicle steering apparatus according to the second embodiment, when the target azimuth angle setting control unit 30 that performs azimuth angle feedback control fails, the azimuth angle feedback control failure diagnosis unit 51 diagnoses the failure and switches. The operation can be maintained by switching to the target tire angle setting control unit 31 by the unit 45 and the changeover switch 46. Furthermore, according to the system provided with the mechanical backup mechanism, the safety can be ensured because the mechanical backup system can be operated. Furthermore, the steering method using the mechanical backup system is a tire angle control steering method, but in this embodiment, since the driver has mastered the tire angle control steering method in normal driving, the steering is easy even in the event of a failure. It can be carried out.

  FIG. 6 is a block diagram of a vehicle steering apparatus according to the third embodiment of the present invention. In the third embodiment, the control device 80 includes a gain variable unit 81 and a steering response instead of the switching unit 45, the changeover switch 46, and the control switching region setting unit 47 in the control device 22 of the first embodiment shown in FIG. A characteristic setting unit 82 is provided. Further, only the configuration of the target azimuth setting controller 30 shown in FIG. 2 is provided, and the target tire angle setting controller 31 is not provided. The same components as those in the first embodiment are denoted by the same reference numerals, and description thereof is omitted. The gain variable unit 81 individually changes the ratio k1 between the steering angle of the steering wheel and the target azimuth angle in the target azimuth angle setting unit 35 and the ratio k2 to be applied to the signal related to the vehicle azimuth angle ψ in the azimuth gain unit 41. It has the function of letting A manual controller 83 is connected to the gain variable unit 81. When the manual controller 83 is set to the manual position, the manual controller 83 allows the ratio k1 and the azimuth gain in the target azimuth setting unit 35 to be set. The ratio k2 at 41 can be manually changed individually. When the manual controller 83 is set to the automatic position, the steering response characteristic setting unit 82 causes the signal from the steering angle sensor 48, the signal from the steering torque sensor 15, the signal from the turning angle sensor 20, and the vehicle. Based on the signal from the behavior sensor 18 and the signal from the vehicle speed sensor 16, the optimum ratios k1 and k2 are set, and the signals related to the set ratios k1 and k2 are sent to the gain variable unit 81. The gain variable unit 81 sets the ratio k1 in the target azimuth angle setting unit 35 and the ratio k2 in the azimuth gain 41 based on the received signals related to the ratios k1 and k2.

  The steering response characteristic setting unit 82 is configured by a conversion table storing ratios k1 and k2 set in advance corresponding to combinations of the steering angle, the steering torque, the turning angle, the vehicle behavior, and the vehicle speed. For example, when it is determined that the vehicle is making a circular turn based on the value from each sensor, or when it is detected that the vehicle is traveling at low speed or starting, the ratio k1 in the target azimuth setting unit 35 is set to 1. The ratio k2 in the azimuth gain unit 41 is set to 0, and a signal is sent to the gain variable unit 81. Thereby, the ratio k1 in the target azimuth angle setting unit 35 is set to 1, and the ratio k2 in the azimuth angle gain unit 41 is set to 0. When the ratio k2 (gain coefficient) set by the azimuth gain unit 41 becomes 0, the feedback loop for the azimuth feedback control does not work, and the actual steering angle designation unit 37 always sets the target azimuth setting unit 35. A rudder angle corresponding to the target azimuth is specified. As a result, the same maneuvering as the tire angle control can be performed. Further, by setting the ratio k2 in the azimuth gain unit 41 to a value other than 0, typically 1, the azimuth feedback control control method can be obtained. For example, based on information from the vehicle speed sensor 16, the ratio k1 in the target azimuth angle setting unit 35 is always set to 1 at low speeds, for example, at low speeds from 0 km / h to 5 km / h. By setting the ratio k2 to 0, the driver can perform the same maneuvering as the tire angle control. Further, by detecting the steering state from information such as steering torque, setting the ratio k1 in the target azimuth angle setting unit 35 to 1 and setting the ratio k2 in the azimuth gain unit 41 to 1 even at low speed, It is also possible to utilize azimuth feedback control.

  The gain variable unit 81 receives the signal from the manual controller 83 and the signal from the steering response characteristic setting unit 82 as input, and the target azimuth angle setting unit 35 and the azimuth gain unit 41 respectively receive a signal related to the ratio k1 and the ratio k2. The signals related to are output individually. Based on these signals, the ratio k1 in the target azimuth setting unit 35 and the ratio k2 in the azimuth gain unit 41 are set.

  If the manual controller 83 is used, the steering method of the azimuth feedback control by the target azimuth angle setting control unit 30 and the steering method equivalent to the tire angle control when the ratio k2 in the azimuth gain unit 41 is set to 0 are automatically used. In addition to switching to, both can be switched at the driver's will and the feeling during switching can be improved.

FIG. 7 shows a case where the control equivalent to the azimuth feedback control and the tire angle control is performed by changing the ratio k2 in the azimuth gain unit 41 to 1 or 0 in the steady circle turning state of the third embodiment. 4 is a graph showing temporal changes in steering angle θ, steering torque T _θ , steering angle δ, yaw rate γ, and yaw angle ψ. 7A shows the time change of the steering angle θ, FIG. 7B shows the time change of the steering torque T _θ , and FIG. 7C shows the time change of the steering angle δ and the yaw rate γ. 7D shows the time change of the yaw angle ψ, and FIG. 7E shows the time change of the ratio k2 in the azimuth gain unit 41. The solid line in each graph shows the time change of each value in this embodiment, the ratio k2 in the azimuth gain unit 41 is always 1, and the output when only the azimuth feedback control is used is shown for reference. In the present embodiment, a state in which the steering torque T _θ is continuously output for a certain period of time is regarded as a steady circular turning state, and the ratio k2 is changed from 1 to 0 as shown in FIG. Switch from control to control equivalent to tire angle control. As shown in FIG. 7, steering starts from time T _A and a steady circular turning state starts from time T _B. Determines the steady circular turn when that state continues until time T _C, the ratio k2 of the azimuth angle gain unit 41 is switched set to a tire angle control equivalent to the control to 0, then, T _E from time T _D As the steering torque T _θ decreases, the steering angle δ is reduced, and at the time T _E when T _θ is zero, the ratio k2 is returned from 0 to 1 to switch from the control equivalent to the tire angle control to the azimuth feedback control. . As for other outputs, the yaw rate γ and the yaw angle ψ, the same results as those obtained when the azimuth feedback control is performed as shown in FIGS. 7C and 7D are obtained. As described above, according to this embodiment, the steering wheel steering angle θ is kept equal to that of the conventional tire angle control operation, thereby enabling steady circular turning. In the present embodiment, the change in the ratio k2 based on the steering torque is shown. However, the change in the ratio k2 in consideration of the other vehicle state information such as the vehicle speed, the yaw rate, and the lateral acceleration is also possible. This can also be achieved by detecting the turning state without changing the ratio and changing the ratio k2.

  As described above, in the present invention, since the steering is controlled using the tire angle control control system during steady circle turning or low speed driving during normal driving, there is a switch to the mechanical backup mechanism when the steer-by-wire system fails. However, the driver can control without being confused. Furthermore, not only at the time of failure but also by letting the driver know the conventional control system control state during normal driving with an indicator or the like, the driver's response at the time of switching becomes smooth and easy.

  The present invention is used as a steer-by-wire (SBW) type vehicle steering apparatus.

It is the schematic of the structure of the steering apparatus for vehicles which concerns on this invention. 1 is a block configuration diagram of a vehicle steering apparatus according to a first embodiment of the present invention. It is a graph which shows the time change of each state quantity in the steady circle turning state in the vehicles carrying the vehicle steering device concerning a 1st embodiment of the present invention. It is a block block diagram of the steering apparatus for vehicles which concerns on 2nd Embodiment of this invention. It is the schematic of the example of 1 application example of the steering device for vehicles concerning a 2nd embodiment of the present invention. It is a block block diagram of the steering apparatus for vehicles which concerns on 3rd Embodiment of this invention. It is a graph which shows the time change of each state quantity in the steady circle turning state in the vehicles carrying the vehicle steering device concerning a 3rd embodiment of the present invention.

Explanation of symbols

10 Vehicle Steering Device 11 Operation Element (Handle)
DESCRIPTION OF SYMBOLS 12 Steering shaft 13 Operation amount detection part 14 Steering reaction force generation actuator 15 Steering torque sensor 16 Vehicle speed sensor 17 Travel direction detection part 18 Vehicle behavior sensor 19 Steering angle generation part 20 Steering angle sensor 21 Tire 22 Control apparatus (ECU)
30 Target azimuth setting control unit 31 Target tire angle setting control unit 32 Control switching unit

Claims (6)

An operation element for the driver to operate, and an operation amount detection means for detecting an operation amount of the operation element;
In a vehicle steering apparatus, comprising: a steering actuator that changes a direction of a tire; and a control unit that drives the steering actuator according to the operation amount of the operation element.
The control means includes
A target azimuth setting control means for setting a target azimuth according to the operation amount and driving the steering actuator based on the target azimuth;
A target tire angle setting control means for setting a target tire angle according to the operation amount and driving the steering actuator based on the target tire angle;
Switching means for switching to either one of the target azimuth angle setting control means and the target tire angle setting control means according to the running condition of the vehicle,
A vehicle steering apparatus characterized by the above.   2. The vehicle according to claim 1, wherein the switching means switches from the target azimuth angle setting control means to the target tire angle setting control means when the vehicle is in a turning state beyond a predetermined time. Steering device.   The vehicle steering apparatus according to claim 2, wherein the switching means switches from the target tire angle setting control means to the target azimuth angle setting control means when the steering torque of the operation element becomes zero. .   2. The vehicle steering apparatus according to claim 1, wherein the switching means switches from the target azimuth angle setting control means to the target tire angle setting control means at a low speed or at a start. An operation element for the driver to operate, and an operation amount detection means for detecting an operation amount of the operation element;
By a steering actuator that changes the direction of the tire, vehicle traveling direction detection means that detects the vehicle traveling direction, and a target azimuth according to the operation amount of the operation element and azimuth feedback control based on the vehicle traveling direction In a vehicle steering apparatus comprising control means for driving the steering actuator,
The control means includes
Target azimuth setting means for setting the target azimuth according to the operation amount;
Azimuth angle calculating means for calculating a vehicle azimuth angle based on the vehicle traveling direction detected by the vehicle traveling direction detection means;
Azimuth gain means for multiplying the vehicle azimuth angle output from the azimuth angle calculation means by a gain coefficient and outputting a multiplication azimuth angle;
Driving means for driving the steering actuator based on a difference between the target azimuth angle and the multiplication azimuth angle;
Gain varying means for changing the gain coefficient according to the running condition of the vehicle,
A vehicle steering apparatus characterized by the above.   The gain variable means sets the gain coefficient of the azimuth gain means to 0 to execute control equivalent to tire angle control, sets the gain coefficient to a value other than 0, and performs the azimuth feedback control. 6. The vehicle steering apparatus according to claim 5, wherein the vehicle steering apparatus is executed.

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