JP5282870B2 - Wheel turning device and turning actuator neutral position return method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a wheel steering device capable of returning a steering actuator from an operating position to a neutral position with a high degree of accuracy without an increase in cost. <P>SOLUTION: An ECU 35 shifts the control mode of the steering actuator 20 to a forced control mode by the input of an external signal from a failure diagnosis tool T (S12, S14). In this forced control mode, target actuation amount L* of the steering actuator 20 necessary to return the steering actuator 20 from an existing position to the neutral position is calculated based on a control map in which the operation amount of steering wheel 10 operated during the forced control mode is made to correspond to the target actuation amount L* (S18). The steering actuator 20 is actuated by the calculated target actuation amount L* (S20, S26, S28), and thereby, the steering actuator 20 is returned to the neutral position. <P>COPYRIGHT: (C)2010,JPO&amp;INPIT

Description

  The present invention relates to a wheel steering device that is a device for turning left and right front wheels or left and right rear wheels of a vehicle, and in particular, a vehicle including a control mechanism for returning a steering actuator that turns wheels to a neutral position. The present invention relates to a wheel turning device and a turning actuator neutral position return method performed to return the turning actuator to a neutral position.

  A wheel steering device including a rear wheel steering device that steers left and right rear wheels based on a steering state of left and right front wheels and an operation state of a steering handle for steering left and right front wheels is known. This wheel steering device controls the left and right rear wheels in the opposite phase or the same phase with respect to the left and right front wheels according to the vehicle speed, or steers the left and right rear wheels when the vehicle receives a crosswind to prevent the vehicle from wobbling. By performing the control to prevent, it has a function of improving the steering stability.

Also, this type of wheel steering device stops the steering of the left and right rear wheels from the viewpoint of safety when the steering control of the left and right rear wheels is abnormal. In this case, the steering actuator for turning the left and right rear wheels is promptly returned to the neutral position at the repair shop. Patent Document 1 employs a hydraulically operated rear wheel steering device, and when the rear wheel steering control becomes abnormal, the steering actuator is placed in a neutral position by the biasing force of a spring disposed in the hydraulic cylinder. A four-wheel steering device provided with a mechanism for returning to the above is described.
Japanese Patent Laid-Open No. 62-146773

  The four-wheel steering device described in Patent Document 1 has a problem that accuracy is poor because the neutral position of the steering actuator fluctuates due to a spring mounting error or deterioration. In addition to the method described in Patent Document 1, an absolute angle detection sensor for detecting the absolute angle of the rear wheel turning angle with respect to the axle is attached to the left and right rear wheels, and the absolute angle detection sensor is shifted to a position where it becomes 0 °. A method of returning the steered actuator to the neutral position by operating the rudder actuator is conceivable. However, in this case, problems such as an increase in cost due to the installation of the absolute angle detection sensor, an increase in the number of assembling steps for assembling the absolute angle sensor with high accuracy, and deterioration in accuracy due to an assembly error occur.

  The present invention has been made to address the above problems, and has a mechanism for returning a steered actuator to a neutral position with high accuracy without increasing costs, and a method for returning a steered actuator neutral position. The purpose is to provide.

A feature of the present invention is a wheel steering apparatus comprising a steering actuator for steering left and right rear wheels, a steering handle for steering left and right front wheels, and a control means for controlling the operation of the steering actuator. The control means changes the control mode for controlling the operation of the steered actuator by an input of an external signal to a forced control mode for controlling the operation of the steered actuator so that the steered actuator returns to a neutral position. And an operation amount necessary for the steered actuator to return to the neutral position in the forced control mode based on the operation amount of the steering handle in the steering wheel operation performed during the forced control mode. Target operation amount calculation means for calculating a target operation amount, and the steering actuator in the forced control mode, the target operation Lies in the intended to comprise an actuator operating means for operating only the.

  According to the above invention, the control means of the wheel steering device sets the operation control mode of the steering actuator to the forced control mode that is a control mode for returning the steering actuator to the neutral position by an external signal input. In this forced control mode, the target operation amount of the steering actuator that steers the wheels (for example, the left and right rear wheels) is calculated based on the operation amount of the steering handle in the steering wheel operation performed during the forced control mode, for example. Then, the steering actuator is returned to the neutral position by operating the steering actuator by the calculated target operation amount. Thus, the present invention calculates the target operation amount of the steering actuator and operates the steering actuator according to the target operation amount, so that the steering actuator is neutralized mechanically by a spring or the like as in the prior art. Compared with returning to the position, the return accuracy to the neutral position is improved. Further, the steering actuator can be returned to the neutral position while keeping the cost down without using an absolute angle detection sensor or the like. In addition, the target operation amount can be accurately calculated by calculating the target operation amount based on the operation amount in the steering wheel operation.

  In the above invention, the input of an external signal is an input of a signal from a device other than the control device to the control device. For example, a failure diagnosis tool provided in a repair shop may be electrically connected to the control means, and an external signal may be input from the failure diagnosis tool to the control means. Further, the neutral position of the steering actuator is the position of the steering actuator when the turning angle of the wheels (for example, left and right rear wheels) steered by the steering actuator is 0 °. The forced control mode is one of the control modes for controlling the operation of the turning actuator by the control means. The control means may control the operation of the steering actuator according to another control mode. For example, the operation of the actuator may be controlled according to a control mode for controlling the operation of the steered actuator according to the vehicle speed, a control mode for locking the steered wheel at the time of failure, or the like. The control means switches from these control modes to the forced control mode when an external signal is input. In the present invention, the steering handle may be for turning the left and right front wheels. In this case, the steering actuator may be one that steers the left and right rear wheels. Further, if the vehicle adopts a steer-by-wire type wheel steering mechanism, the steering handle may operate a wheel (for example, left and right front wheels) operated by an actuator, or a wheel that does not (for example, left and right rear wheels). ) May be operated.

  Further, the target operation amount calculation means is configured to perform the target operation based on setting means in which a relationship between the operation amount of the steering handle and the target operation amount in a steering wheel operation performed during the forced control mode is set in advance. It is good to calculate quantity. According to this, the steering handle is operated by an operator or the like during the forced control mode. The relationship between the operation amount and the target operation amount at this time is preset by the setting means, and the control means calculates the target operation amount from the operation amount based on the setting means. By calculating the target operation amount using the setting means, the operation amount of the steering handle can be made to correspond to the target operation amount. As a result, the target operation amount is accurately calculated by the operation of the steering handle. be able to.

  The setting means represents a correspondence relationship between the operation amount of the steering handle and the target operation amount of the steered actuator in the steering handle operation performed during the forced control mode. The target operating amount is determined. In this case, the setting means may be a control map (control table) in which a target operation amount determined according to the amount of operation of the steering wheel is stored, or the amount of operation of the steering wheel and the target The relationship with the operation amount may be expressed by a function. Further, the setting means may be stored in the control means.

  Further, the steering handle operation performed during the forced control mode may be an operation of returning the steering handle from an operation position at which a current position of the steered actuator can be estimated to a neutral position. According to this, since the current position of the steering actuator can be estimated from the operation position of the steering handle, the operation amount and the target operation amount when the steering handle is operated from the operation position to the neutral position (the steering actuator is currently The target operation amount can be estimated from the operation amount by associating with the operation amount for operating from the position to the neutral position. Therefore, by creating the setting means so that the operation amount of the steering wheel corresponds to the target operation amount estimated therefrom, the target operation amount is accurately calculated from the operation amount of the steering wheel based on the setting means. be able to.

  In particular, when the wheel steering device is a four-wheel steering device, that is, when the left and right front wheels are steered by the steering handle and the left and right rear wheels are steered by the steering actuator, the current position of the steering actuator can be estimated. The steering position of the steering wheel is steered so that the turning angle of the left and right front wheels is equal to the turning angle of the left and right rear wheels so that the vehicle can run in a straight line diagonally (hereinafter referred to as a skew state). It may be an operation position of the steering handle when the handle is operated (or a rotational position in the case of a rotating steering handle). According to this, when the vehicle is in a skew state, the turning angle of the left and right rear wheels is equal to the turning angle of the left and right front wheels. From this, the current position of the steering actuator can also be easily estimated.

  The amount of operation when the steering wheel is returned from the operation position to the neutral position in the skew state is correlated with the amount of steering when the left and right rear wheels in the skew state are returned from the steering position to the neutral position. The steering amount is correlated with the operation amount (target operation amount) when the steering actuator in the skew state is returned from the current position to the neutral position. That is, there is a correlation between the steering amount from the operation position of the steering wheel to the neutral position in the skew state and the target operation amount. Therefore, the setting means is created based on the correlation, and the target operation amount is calculated based on the created setting means, so that the accurate target operation amount can be calculated, and the steering actuator can be accurately neutralized. Can be returned to position. Further, the work performed by the operator to return the steering actuator to the neutral position is merely to bring the vehicle into a skewed state and then return the steering handle to the neutral position. The steering actuator can be accurately returned to the neutral position only by performing such a simple operation.

  Further, the current position of the steering actuator is estimated in advance, and the amount of operation of the steering wheel in the steering wheel operation performed during the forced control mode is determined based on the estimated current position. May be. According to this, since the current position of the steering actuator is estimated in advance by an operator or the like, it is estimated how much the steering actuator will return to the neutral position from the estimated current position. can do. That is, the target operating amount can be estimated. Therefore, the operator estimates the target operation amount from the estimated current position, and the estimated target operation amount is, for example, the contents of the setting means described in the maintenance manual, that is, the relationship between the operation amount of the steering wheel and the target operation amount. By checking the necessary steering handle operation amount in light of the above, and operating the steering handle by the checked operation amount, the steered actuator can be operated by the target operation amount. There are various methods for estimating the current position of the steering actuator. For example, the displacement from the neutral position of the steering actuator at the current position is measured by a measuring device (for example, calipers), or the left and right rear wheels Can be estimated by measuring the turning angle of the steering wheel with a measuring device and converting it to the displacement of the turning actuator.

  The control means may further include a forced control end means for ending the forced control mode when the steering actuator is operated by the target operation amount. According to this, after the wheel is returned to the neutral position by the operation of the steering actuator in the forced control mode, the forced control mode is ended by the forced control end means.

  The control means is configured to determine whether the vehicle state is a predetermined state during the forced control mode, and when the vehicle state is determined to be a predetermined state by the vehicle state determination stage. It is preferable to further include forced control stopping means for canceling the forced control mode. Depending on the vehicle state, it may not be preferable to return the steering actuator to the neutral position in the forced control mode. Therefore, in such a case, the forced control mode can be stopped by the forced control stop means.

  In this case, the predetermined state includes an ignition OFF state in which the vehicle ignition is OFF, a vehicle traveling state in which the vehicle speed is equal to or higher than a predetermined fine speed, and a current to be supplied to the actuator to cause the actuator to perform a desired operation. Steering angle detection sensor abnormality in which the actuator does not perform the desired operation despite being supplied, and the correct operation cannot be obtained from the steering angle detection sensor that detects the steering angle of the steering wheel State, vehicle speed sensor abnormal state in which correct input cannot be obtained from the vehicle speed sensor for detecting the vehicle speed, voltage drop state in which the supply voltage to the control means is reduced, failure detection state in which the control means has detected a failure, It is good that it is at least any one state.

  The wheel steering device may further include a stop notification unit that notifies the stop of the forced control mode by the forced control stop unit. According to this, it is possible to notify the operator that the forced control mode has been canceled by the notification by the cancellation notification means. The wheel steering apparatus further includes a forced control mode transition notifying means for notifying that the control mode for controlling the operation of the steering actuator by the control means has shifted to the forced control mode. Is good. According to this, it is possible to notify the operator that the control mode of the wheel steering device has been changed to the forced control mode by the notification by the forced control mode transition notification means.

  The control means may further include an operating speed limiting means for limiting the operating speed of the steering actuator that operates during the forced control mode to a predetermined speed or less. According to this, by operating the steering actuator at a relatively low speed equal to or lower than the predetermined speed, the steering actuator can be accurately returned to the neutral position and fixed at that position. In this case, the predetermined speed is 0.1 deg. In terms of the turning angular speed of the wheel steered by the turning actuator. / Sec. ~ 3 deg. / Sec. Good speed. If the speed is in such a range, the steering actuator can be reliably returned to the neutral position with high accuracy.

  Another feature of the present invention is a neutral position return method for turning a steering actuator for turning left and right rear wheels of a vehicle to a neutral position, and estimating a current position of the steering actuator. The steering actuator has a control mode in which the control means controls the operation of the steering actuator by inputting an external signal to a current position estimating step and a control means for controlling the operation of the steering actuator. A mode transition step for setting a forced control mode to control the operation of the steering actuator so as to return from the current position to the neutral position, a steering handle operating step for operating a steering handle for steering left and right front wheels, and the steering handle operating step The steering wheel operation amount operated at, and the steering actuator from the current position to the neutral position A target operation amount calculation step in which the control means calculates the target operation amount based on setting means in which a relationship with a target operation amount that is an operation amount necessary to operate until the target operation amount is set in advance; and the target operation amount A neutral position return method including a neutral position return step of returning the steered actuator to a neutral position by operating the steered actuator by the operation amount calculated in the calculating step. .

  According to the above invention, the current position of the steering actuator is first estimated. Next, the control mode of the control means is set to the forced control mode by an external signal input, and the steering wheel is operated during the forced control mode. Based on the operation amount, the target operation amount of the steering actuator is calculated based on the setting means, the steering actuator is operated by the calculated target operation amount, and the steering actuator is returned to the neutral position. Thus, the present invention calculates the target operation amount of the steering actuator from the setting means using the operation amount of the steering handle and then operates the steering actuator according to the target operation amount. In addition, the steered actuator can be returned to the neutral position with higher accuracy than when the steered actuator is mechanically returned to the neutral position by a spring or the like. Further, the steering actuator can be returned to the neutral position while keeping the cost down without using an absolute angle detection sensor or the like.

In this case, the current position estimating step is a step of estimating the current position by operating the steering handle to linearly travel the vehicle in an oblique direction so that the front wheel turning angle coincides with the rear wheel turning angle. The steering handle operating step may be a step of operating the steering handle so that the vehicle returns to the neutral position from the operation position in a state where the vehicle can travel in a straight line. According to this, the operator operates the steering handle until the vehicle is in the skew state, and then the target operation amount is calculated by a simple operation of simply returning the steering handle to the neutral position, and the steering actuator is neutral. Return to position.

  The current position estimating step is a step in which an operator measures the current position of the steered actuator using a measuring device, and the steering handle operating step is performed at the current position measured in the current position estimating step. Based on the above, even if the operator investigates the operation amount of the steering handle corresponding to the target operation amount set by the setting means, and the operator operates the steering handle by the investigated operation amount. Good. According to this, the operator directly measures the current position of the steered actuator in advance using a measuring device. The target operation amount can be estimated from the measured current position of the steering actuator. Based on the measured current position, the operator refers to a maintenance manual that describes the relationship between the target operating amount set in the setting means and the operating amount of the steering wheel, and investigates the operating amount corresponding to the target operating amount. To do. Then, the steering handle is operated by the investigated operation amount. Thereby, the target operation amount is calculated, and the steered actuator is operated by the calculated target operation amount. In this way, the operator measures the operation amount of the steering actuator, compares the measured value against a maintenance manual, etc., and the steering actuator is neutralized by a simple operation of operating the steering handle by the obtained operation amount. Return to position.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. FIG. 1 is an overall schematic diagram of a wheel steering apparatus according to the present embodiment.

  The wheel steering device 1 shown in FIG. 1 is a four-wheel steering device. The wheel turning device 1 includes a steering handle 10 that is steered by a driver and steers the left and right front wheels Wfl and Wfr by the steering operation. The steering handle 10 is connected to the upper end (lower end in the figure) of the steering shaft 11 so as to rotate integrally. A pinion gear 12 is provided at the lower end (the upper end in the figure) of the steering shaft 11 so as to be integrally rotatable. The pinion gear 12 meshes with rack teeth 13a provided on the rack bar 13, and the rack bar 13 is driven in the axial direction by the rotation thereof. The rack bar 13 connects the left and right front wheels Wfl and Wfr at both ends thereof via a tie rod and a knuckle arm (not shown) so that the left and right front wheels Wfl and Wfr are steered by displacement in the axial direction.

  The wheel turning device 1 includes a turning actuator 20 that turns the left and right rear wheels Wrl and Wrr. The steering actuator 20 includes an electric motor 21, a rear wheel steering shaft 22, and a ball screw feed mechanism 23. The electric motor 21 is assembled on the outer periphery of the rear wheel steering shaft 22. The rear wheel turning shaft 22 is connected to the left and right rear wheels Wrl and Wrr as steered wheels via a tie rod and a knuckle arm (not shown) at both ends so that the left and right rear wheels Wrl and Wrr can be steered. To steer. The rotation of the electric motor 21 is transmitted to the rear wheel steering shaft 22 via a ball screw feed mechanism 23 assembled on the outer periphery of the rear wheel steering shaft 22. The ball screw feed mechanism 23 decelerates the rotation of the electric motor 21 and converts the rotational motion into a linear motion and transmits it to the rear wheel turning shaft 22. Therefore, for example, when the electric motor 21 rotates in the forward direction, the rear wheel turning shaft 22 is displaced in one axial direction, whereby the left and right rear wheels Wrl, Wrr are steered in one direction, for example, the right direction. On the other hand, when the electric motor rotates in the reverse direction (opposite to the forward direction), the rear wheel turning shaft 22 is displaced in the other axial direction, thereby causing the left and right rear wheels Wrl, Wrr to rotate in the other direction, for example, the left direction. Steered. In this way, the steering actuator 20 steers the left and right rear wheels Wrl and Wrr by operating the rear wheel steering shaft 22 in the axial direction.

  Next, an electric control device that controls the operation of the steering actuator 20 will be described. The electric control device includes a rear wheel steering angle sensor 31, a vehicle speed sensor 32, a yaw rate sensor 33, and a steering angle sensor 34. The rear wheel turning angle sensor 31 includes an encoder incorporated in the electric motor 21 and detects the turning angle (rear wheel turning angle) δr of the left and right rear wheels Wrl and Wrr by detecting the rotation angle of the electric motor 21. . When the turning angle is “0”, the steering position of the left and right rear wheels Wrl, Wrr is the neutral position, and the steering is performed when the left and right rear wheels Wrl, Wrr are turning leftward from the neutral position. The angle is represented by a negative value, and the turning angle when turning rightward is represented by a positive value. The vehicle speed sensor 32 detects the vehicle speed V. The yaw rate sensor 33 detects the yaw rate γ around the center of gravity of the vehicle body. The steering angle sensor 34 is attached to the steering shaft 11 connected to the steering handle 10, and detects the steering angle θ of the steering handle 10 by detecting the rotation angle of the steering shaft 11. The steering angle θ is “0” when the turning positions of the left and right front wheels Wfl and Wfr are in the neutral position, and is expressed as a negative value when turning leftward from the neutral position. If the vehicle is steered, it shall be expressed as a positive value.

  The rear wheel turning angle sensor 31, the vehicle speed sensor 32, the yaw rate sensor 33, and the steering angle sensor 34 are connected to an electronic control unit (hereinafter referred to as ECU) 35 that constitutes the control means of the present invention. The ECU 35 includes a microcomputer including a CPU, a ROM, a RAM, and the like as main components. The ECU 35 controls the driving of the electric motor 21 via the drive circuit 36 in accordance with detection signals from the sensors. Control the operation.

  In addition, the wheel steering device 1 is provided with an alarm device 40. The alarm device 40 is electrically connected to the ECU 35 and generates a sound with the display unit 41 assembled at a position (for example, in a meter cluster) that can be visually recognized by an operator (operator of the steering handle 10). And a sound generator 42. The display unit 41 includes, for example, a lamp or a display panel. The sound generator 42 is composed of, for example, a speaker.

  As for ECU35, the control mode for controlling the action | operation of the steering actuator 20 is normally set to the automatic control mode. In this automatic control mode, the ECU 35 determines the traveling state of the vehicle from various sensors, and controls the operation of the steering actuator 20 so that the left and right rear wheels Wrl, Wrr perform a desired steering according to the determination result. . For example, when the vehicle is traveling at a predetermined vehicle speed V1 or higher, the ECU 35 operates the steering actuator 20 so that the left and right front wheels Wfl and Wfr and the left and right rear wheels Wrl and Wrr are in the same direction (same phase). Control. As a result, for example, the vehicle body slip angle at the time of lane change can be reduced to make it less susceptible to the influence of the yaw inertia force of the vehicle body, and the turn of the vehicle body after the lane change can be reduced. Further, when the vehicle receives a crosswind while traveling, the ECU 35 controls the operation of the steering actuator 20 to turn the left and right rear wheels Wrl and Wrr so that the vehicle body does not fluctuate due to the crosswind. This improves the crosswind stability. Thus, high steering stability is realized by turning the left and right rear wheels Wrl and Wrr according to the traveling state.

  However, when an abnormality occurs in the control system of the wheel turning device 1, it is unclear whether the rear wheel turning angle sensor 31 detects the right turning angle of the left and right rear wheels Wrl and Wrr. In this case, the ECU 35 sets the operation control mode of the steering actuator 20 to the lock mode, fixes the left and right rear wheels Wrl and Wrr at the steering position at that time, and irrespective of the steering of the left and right front wheels Wfl and Wfr. The operation of the steering actuator 20 is controlled so that the left and right rear wheels Wrl, Wrr are not steered. Therefore, the steering actuator 20 is locked while being displaced from the neutral position to the current position, which is the operation position when the left and right rear wheels Wrl, Wrr are at the steering position. Then, the vehicle is transported to a repair shop or the like in the locked state, and the steering actuator 20 is returned from the current position to the neutral position at the repair shop according to the following procedure.

  First, the current position of the steering actuator 20 in the locked state is estimated (current position estimation step). For this purpose, the operator steers the steering wheel 10 to steer the left and right front wheels Wfl, Wfr, and the vehicle S can travel straight in the diagonal direction indicated by the arrow as shown in FIG. Line state). When the vehicle is skewed, the turning angle (rear wheel turning angle) δr of the left and right rear wheels Wrl and Wrr is equal to the turning angle (front wheel turning angle) δf of the left and right front wheels Wfl and Wfr (δr = δf ). Therefore, the front wheel turning angle δf can be estimated from the operation position (steering angle θ) of the steering wheel 10 when the vehicle is in the skew state, and the rear wheel turning angle δr can be estimated from the front wheel turning angle δf. The amount of displacement from the current position of the steering actuator 20, specifically, the neutral position of the rear wheel steering shaft 22, can be estimated from the steering angle δr. Thus, the operation position of the steering handle 10 when the vehicle is in the skew state is an operation position at which the current position of the steering actuator 20 can be estimated. Whether the vehicle is in a skewed state depends on whether the vehicle is traveling on a straight lane and the steering angle is neutral, or the vehicle is traveling with the yaw rate being zero, and the steering angle is neutral. It can be judged by whether or not. Alternatively, the determination can be made based on whether or not the vehicle can travel on a straight lane by traveling at a slow speed, or whether or not the yaw rate is zero.

  After estimating the operation amount of the steering actuator 20 in the current position estimation step, the operator connects the failure diagnosis tool T to the vehicle. As a result, the ECU 35 is electrically connected to the failure diagnosis tool T as shown in FIG. The failure diagnosis tool T is provided in a repair shop or the like, and enables communication with the ECU 35 by being electrically connected to the ECU 35 via a connection member DLC such as a data link connector. The failure diagnosis tool T has operation buttons and a display screen. Note that the ECU 35 has a self-diagnosis function and connects the failure diagnosis tool T, and the operator operates the failure diagnosis tool T according to the instructions displayed on the display screen, thereby turning the wheel. A failure diagnosis of the device 1 can be performed. In this embodiment, the ECU 35 inputs an external signal using the failure diagnosis tool T and executes the program shown in FIG. 3, whereby the steered actuator 20 is returned from the current position to the neutral position.

  The program of FIG. 3 is started in step S10, and in next step S12, the ECU 35 determines whether a mode transition signal is input from the outside. This mode transition signal can be input by the operator via the failure diagnosis tool T connected to the ECU 35. If it is determined in step S12 that the mode transition signal has not been input, the ECU 35 proceeds to step S36 and terminates the execution of this program. If it is determined that the mode shift signal is input, the ECU 35 shifts the operation control mode of the steering actuator 20 to the forced control mode in the next step S14. That is, on the condition that the determination in step S12 is Yes, the ECU 35 shifts the control mode of the steered actuator 20 to the forced control mode (mode shift means, mode shift step). Note that the mode transition process in step S14 is a step provided for clarity of explanation, and is omitted in the actual program creation, and the mode transition process is performed only because the determination in step S12 is Yes. You can go.

  After shifting the control mode to the forced control mode in step S14, the ECU 35 proceeds to step S16, and outputs a notification command to the display unit 41 and the sound generation unit 42 of the alarm device 40 in this step S16 (first notification). processing). Thereby, the alarm device 40 notifies the operator of the transition to the forced control mode. That is, the ECU 35 operates the display unit 41 to turn on, for example, a warning lamp or display a message to the effect that the display has shifted to the forced control mode in the display panel. In addition, the ECU 35 operates the sound generator 42 to output, for example, a first alarm sound from the speaker, or to output a message to the effect that the mode has shifted to the forced control mode from the speaker. Thus, the operator can recognize that the control mode of the ECU 35 has shifted to the forced control mode. Thereafter, the ECU 35 proceeds to step S18.

  In step S18, the ECU 35 calculates a target operation amount L * that is an operation amount necessary to return the steering actuator 20 from the current position to the neutral position (target operation amount calculation means, target operation amount calculation step). The target operation amount L * is, for example, the amount of axial displacement of the rear wheel turning shaft 22 necessary for returning the turning actuator 20 from the current position to the neutral position. The target operation amount L * may be substituted with the target rotation amount of the electric motor 21. Here, during the forced control mode, the operator operates the steering handle 10 by a desired amount (steering handle operation step), and the target operation amount L * is calculated based on the operation amount at this time. The target operation amount L * and the operation amount of the steering handle 10 operated by the operator are determined as follows.

  The ECU 35 stores a control map or function as setting means in which the relationship between the operation amount of the steering handle 10 during the forced control mode and the target operation amount L * of the steering actuator 20 is preset. FIG. 4 shows an example of a control map (function). The horizontal axis of this control map is the operation amount of the steering wheel 10 in the steering wheel operation performed during the forced control mode, and the vertical axis is the target operation amount L * of the steering actuator 20. In this figure, for example, when the left and right front wheels Wfl and Wfr and the left and right rear wheels Wrl and Wrr are steered to the right, the steering wheel operation amount and the steered actuator operation amount are shown as positive values, and when the steer is steered to the left The manipulated variable and actuated variable are shown as negative values.

  Here, for example, the steering angle of the steering handle 10 when the control mode of the steering actuator 20 by the ECU 35 shifts to the forced control mode is θ1, and the steering angle of the steering handle 10 after being operated in the forced control mode is θ2. Then, the operation amount A by the steering wheel operation performed during the forced control mode is θ2−θ1. The operation amount of the steering actuator 20 corresponding to the operation amount A is B from the control map of FIG. Therefore, the target operation amount L * of the steering actuator 20 corresponding to the handle operation amount A is B.

  The ECU 35 calculates the target operation amount L * as described above from the control map of FIG. 4 based on the operation amount of the steering wheel 10 in the steering wheel operation performed during the forced control mode. If the steered actuator 20 is actuated by the calculated target actuating amount L *, the steered actuator 20 is returned from the operating position (current position) in the locked state to the neutral position, and the left and right rear wheels Wrl, Wrr also return to the neutral position. . In this case, the predetermined operation amount and the target operation amount L * of the steering wheel 10 are calculated so that the ECU 35 can calculate an accurate target operation amount L * by referring to the control map from the operation amount of the steering handle 10. It is necessary to create a control map corresponding to. In the present embodiment, as the predetermined operation amount, the operation amount for returning the steering handle 10 from the operation position when the vehicle is in the skew state to the neutral position is set, and the operation amount at this time and the target operation amount L Create a control map so that * corresponds.

  A specific example of creating a control map is shown below. It is assumed that the front wheel turning angle δf and the rear wheel turning angle δr of the vehicle that has been skewed in the current position estimating step are equal, and this turning angle is represented by δ (= δr = δf). In order to steer the left and right front wheels Wfl and Wfr from this skew state to the neutral position, the left and right front wheels Wfl and Wfr must be steered by −δ. Here, the amount of steering of the left and right front wheels Wfl, Wfr (the amount of angle to steer) and the amount of operation of the steering handle 10 (steering angle) are proportional to each other. By operating the steering handle 10 by this operation amount with the operation amount as K1 · (−δ), the steering handle 10 returns to the neutral position and the left and right front wheels Wfl, Wfr also return to the neutral position. In order to return the steering actuator 20 from the current position in the skew state to the neutral position, the left and right rear wheels Wrl and Wrr must be steered by −δ. The steering amount of the left and right rear wheels Wrl, Wrr (the amount of angle to be steered) and the operation amount of the steering actuator 20 are proportional to each other, and if the proportionality coefficient is K2, the steering actuator is only K2 · (−δ). By actuating, the steering actuator 20 and the left and right rear wheels Wrl, Wrr return to the neutral position. That is, the target operation amount L * is K2 · (−δ). Therefore, the steering handle 10 is made neutral by setting the origin as a point where the steering wheel operation amount is 0 and the target operation amount is 0, and creating a control map that passes through this origin and is represented by a straight line with a slope of K2 / K1. The operation amount for returning to the position corresponds to the target operation amount L *. The ECU 35 stores a control map created with such a relationship.

  Therefore, the operator performs an operation of returning the steering handle 10 of the vehicle that has been in a skew state in advance from the operation position to the neutral position during the forced control mode. By this operation, the left and right front wheels Wfl and Wfr in the skew state return to the neutral position. Further, the ECU 35 calculates the target operation amount L * from the control map representing the relationship between the operation amount and the target operation amount based on the operation amount of the steering handle 10 obtained at that time.

  After the ECU 35 calculates the target operating amount L * of the steering actuator 20 in step S18, the ECU 35 proceeds to step S20 and outputs a drive start command to the electric motor 21. As a result, the electric motor 21 is driven and the steering actuator 20 is actuated (actuator actuating means, neutral position return step). By driving the electric motor 21, the rotation of the electric motor 21 is decelerated by the ball screw feeding mechanism 23 and is converted into an axial displacement of the rear wheel turning shaft 22. As a result, the rear wheel turning shaft 22 is displaced in the axial direction, and the left and right rear wheels Wrl and Wrr are steered.

  Subsequently, the ECU 35 proceeds to step S22 and performs a speed control process. This speed control process is a process in which the operating speed of the steered actuator 20, specifically, the axial movement speed until the rear wheel steered shaft 22 reaches the neutral position is set to a predetermined speed or less. This can be performed, for example, by suppressing the increase in the operating speed of the rear wheel turning shaft 22 by making the rotational displacement or the rotational angular velocity of the electric motor 21 (for example, performing a low-pass filter process). Alternatively, the current supplied to the electric motor 21 can be limited and the operation speed can be operated at a constant low speed. In this case, the speed of the rear wheel turning shaft 22 is 0.1 deg. In terms of the turning angular speed of the left and right rear wheels Wrl and Wrr. / Sec-3deg. It is preferable to be within the range of / sec.

Next, the ECU 35 proceeds to step S24, and determines whether the vehicle state is not in the abnormal state shown below and the steering actuator 20 may be operated in the forced control mode (vehicle state determination). means).
An ignition OFF state in which the vehicle ignition is OFF. A vehicle running state in which the vehicle speed is equal to or higher than a predetermined fine speed V2. A current to be supplied to cause the electric motor 21 to perform a desired operation is flowing. In other words, the electric motor 21 does not perform a desired operation. The electric motor does not operate properly. The steering angle sensor is in an abnormal state in which the correct input is not obtained from the steering angle sensor 34. The correct input is not obtained from the vehicle speed sensor 32. Vehicle speed sensor abnormal state which is the state, voltage drop state where the supply voltage to the ECU 35 is lowered, failure detection state where the ECU 35 has detected its own failure

  If it is determined that the vehicle state does not correspond to any of the abnormal states (S22: Yes), the process proceeds to step S24. On the other hand, when it determines with falling into at least one of the said abnormal states (S22: No), it progresses to step S32. In step S32, the ECU 35 performs a process of stopping the operation control of the steered actuator 20 in the forced control mode (forced control stopping unit). Thereafter, the ECU 35 proceeds to step S34 and outputs a notification command to the alarm device 40 (second notification processing). Thereby, the alarm device 40 notifies the operator that the operation control of the steering actuator 20 in the forced control mode is stopped using the display unit 41 and the sound generation unit 42. That is, the ECU 35 operates the display unit 41 to turn on a warning lamp, for example, or display a message indicating that the operation control of the steering actuator 20 in the forced control mode is stopped in the display panel. In addition, the ECU 35 operates the sound generation unit 42 to output, for example, a second alarm sound with a sound different from the first alarm sound from the speaker, or a message indicating that the operation control in the forced control mode is stopped. The sound is output from the speaker. Thereafter, the ECU 35 proceeds to step S36 and ends the execution of this program.

  Here, among the above-described abnormal states, when the ignition is OFF, the steered actuator 20 cannot be operated because the operation of the vehicle is stopped. Therefore, in such a vehicle state, the operation control of the turning actuator 20 in the forced control mode is stopped. Further, when the vehicle is running, if the left and right rear wheels Wrl and Wrr are steered in the forced control mode, the vehicle may behave unexpectedly. Therefore, in such a vehicle state, the operation of the steering actuator 20 in the forced control mode is prohibited to ensure safety. When the electric motor is in a defective operation state, there is a possibility that the steering actuator 20 is not returned to the neutral position even if the steering actuator 20 is operated by the target operation amount calculated in the forced control mode. Therefore, also in this case, the operation control of the steering actuator 20 in the forced control mode is stopped. When the steering angle sensor is in an abnormal state, the target operation amount of the steering actuator 20 obtained based on the operation amount of the steering handle 10 may be different from the true target operation amount. Therefore, also in this case, the operation control of the steering actuator 20 in the forced control mode is stopped. When the vehicle speed sensor is in an abnormal state, there is a possibility that the vehicle is in a traveling state. When in the voltage drop state or the failure detection state, the ECU 35 may not operate normally, so the operation control of the turning actuator 20 in the forced control mode is stopped.

  On the other hand, if the determination result in step S24 is Yes, the ECU 35 proceeds to step S26, and determines whether the operation amount L of the steering actuator 20 has reached the target operation amount L * in this step S26. The operation amount L of the turning actuator 20 can be calculated from the motor rotation amount obtained from the signal output from the encoder incorporated in the electric motor 21. When the operation amount L does not reach the target operation amount L * (S26: No), the process returns to step S24, and after confirming the vehicle state, it is determined again whether the operation amount L becomes the target operation amount L *. When the operation amount L becomes the target operation amount L * (S26: Yes), the process proceeds to step S28. In step S <b> 28, the ECU 35 outputs a drive stop command to the electric motor 21. As a result, the steering actuator 20 stops operating. At this time, the steering actuator 20 and the left and right rear wheels Wrl, Wrr have returned to the neutral position. Further, the left and right front wheels Wfl, Wfr are also returned to the neutral position by the operation of the steering handle 10 by the operator. Thereafter, the ECU 35 proceeds to step S30 to end the operation control of the steered actuator 20 in the forced control mode (forced control ending means). Further, the process proceeds to step S36 to finish the execution of this program.

  As described above, in the wheel turning device 1 of the present embodiment, the ECU 35 sets the control mode of the turning actuator 20 to the forced control mode by inputting an external signal from the failure diagnosis tool T or the like (S12, S14). In this forced control mode, the target operating amount L * of the steering actuator 20 necessary to return the steering actuator 20 from the current position to the neutral position is the steering handle 10 that is operated during the forced control mode. Is calculated based on a control map in which the manipulated variable and the target operating amount L * are associated with each other (S18). Then, when the turning actuator 20 is operated by the target operation amount L *, the turning actuator 20 returns to the neutral position (S20, S26, S28). Therefore, the steered actuator 20 and the left and right rear wheels Wrl and Wrr can be returned to the neutral position with higher accuracy than when the steered actuator is mechanically operated by a spring or the like as in the prior art. Further, it is possible to return the steering actuator 20 and the left and right rear wheels Wrl and Wrr to the neutral position while reducing the cost without using an absolute angle detection sensor or the like.

  Further, the target operation amount L * is calculated based on a control map which is a setting means in which the relationship between the operation amount of the steering handle 10 and the target operation amount L * in the steering handle operation performed during the forced control mode is set in advance. Therefore, the target operation amount L * can be calculated accurately. Further, the steering handle operation performed during the forced control mode is an operation for returning the steering handle 10 from the operation position when the vehicle is in the skew state to the neutral position. For this reason, the left and right front wheels Wfl and Wfr are returned to the neutral position by this handle operation, and the target operation amount L * calculated from the control map is changed based on the operation amount of the steering handle 10 in the handle operation performed at that time. By operating the rudder actuator 20, the steered actuator 20 and the left and right rear wheels Wrl and Wrr are simultaneously returned to the neutral position.

  Further, the operator only needs to perform a simple operation of operating the steering handle 10 until the vehicle is in a skewed state and returning the steering handle 10 to the neutral position from that state. By this operation, the ECU 35 calculates the target operation amount L *, and the steered actuator 20 is operated by the calculated target operation amount L * to automatically return to the neutral position.

  Further, the ECU 35 determines whether or not the vehicle is in a predetermined abnormal state during the forced control mode (S24), and stops the forced control mode when it is determined as the predetermined abnormal state (S32). This ensures safety and accuracy in operating the steering actuator 20 during the forced control mode. Further, the ECU 35 limits the operating speed of the turning actuator 20 that operates in the forced control mode to a predetermined speed or less (S22). For this reason, the turning actuator 20 can be moved slowly and returned to the neutral position with high accuracy.

  Further, the wheel turning device 1 includes an alarm device 40 that receives a notification command (S32) from the ECU 35 and notifies the suspension of the forced control mode when the forced control mode is stopped. For this reason, the operator can confirm that the forced control mode is stopped by the notification from the alarm device 40. The alarm device 40 receives a notification command (S16) from the ECU 35 when the operation control mode of the steering actuator 20 shifts to the forced control mode, and notifies that the control mode has shifted to the forced control mode. It also has a function. For this reason, the operator can confirm that the control mode of the ECU 35 has become the forced control mode.

  As mentioned above, although embodiment of this invention was described, this invention should not be limited to the said embodiment. For example, in the above-described embodiment, the four-wheel steering device in which the left and right front wheels Wfl and Wfr are steered by the steering handle 10 and the left and right rear wheels Wrl and Wrr are steered by the steering actuator 20 has been described. The present invention is also applied to a steer-by-wire steering apparatus in which the steering wheel operation amount is converted into an electrical signal, and the left and right front wheels Wfl and Wfr are steered by operating the steering actuator in accordance with the converted electrical signal. it can. In this case, the target operation amount, which is the operation amount for returning the steering actuator for turning the left and right front wheels Wfl, Wfr from the current position to the neutral position, is calculated from the control map and the like based on the operation amount of the steering wheel. The steering actuator is returned to the neutral position by operating the steering actuator by the target operation amount.

  In the above embodiment, the current position of the steered actuator 20 is estimated by causing the vehicle to enter a skew state. However, the current position of the steered actuator 20 may be estimated by other methods. For example, the operator may directly measure the amount of displacement from the neutral position of the rear wheel turning shaft 22 using a measuring device such as a caliper, and estimate the current position of the turning actuator 20 based on the obtained measurement result. it can. However, in this case, unlike the above embodiment, the steering handle 10 is not operated to a position where the current position of the steered actuator 20 can be estimated. Therefore, it is not known how much the operator operates the steering handle 10 in the forced control mode to calculate the accurate target operation amount L * from the control map. Therefore, in this case, a table or graph showing the same relationship as the control map is described in a maintenance manual, for example, and the operator compares the measured displacement amount with the table or graph described in the maintenance manual. . Since the target operation amount can be estimated from the measured displacement amount, a necessary operation amount of the steering handle 10 is investigated from a maintenance manual or the like based on the estimation. Then, by operating the steering handle 10 by the investigated operation amount, the ECU 35 calculates an accurate target operation amount L * and operates the steering actuator 20 by the obtained target operation amount L *, thereby turning the steering. The actuator 20 is returned to the neutral position. Even if it does in this way, there exists an effect of this invention.

  In the above embodiment, the ECU 35 calculates the target operation amount based on the control map that represents the relationship between the operation amount of the steering wheel 10 operated during the forced control mode and the target operation amount. The target actuation amount may be calculated based on a control map that represents the relationship between the amount that indirectly represents the manipulated variable and the amount that indirectly represents the target actuation amount. For example, the horizontal axis in the control map can be the turning amount or turning angle of the left and right front wheels Wfl, Wfr, and the vertical axis is the turning angle or turning amount of the left and right rear wheels Wrl, Wrr, the electric motor 21. The rotation amount or rotation speed of the steering wheel 20, the operating speed of the steering actuator 20, and the like. Also, the horizontal axis can be the steering torque value, and the vertical axis can be the operating speed of the steering actuator (rotational angular speed of the electric motor).

  Further, in the above embodiment, the ECU 35 performs the calculation of the target operation amount. However, the ECU 35 is configured to input the calculated target operation amount by causing the control device other than the ECU 35 to calculate the target operation amount. May be. For example, when the vehicle can perform vehicle stability control during cornering, there is a possibility that the control means for controlling the stability constantly monitors the wheel turning angle and the yaw rate. Therefore, the target operating amount may be calculated by the control means, and the ECU 35 may simply input the calculated target operating amount.

1 is an overall schematic diagram of a wheel steering apparatus according to an embodiment of the present invention. It is the schematic which shows the case where a vehicle is in a skew state. It is a program flowchart which ECU in this embodiment performs. It is a figure which shows the control map in this embodiment.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Wheel steering apparatus, 10 ... Steering handle, 11 ... Steering shaft, 20 ... Steering actuator, 21 ... Electric motor, 22 ... Rear-wheel steering shaft, 23 ... Ball screw feed mechanism, 31 ... Rear-wheel steering angle sensor, 32 ... Vehicle speed sensor, 33 ... Yaw rate sensor, 34 ... Steering angle sensor, 35 ... ECU (control means), 36 ... Drive circuit, 40 ... Alarm device (stop notification means, forced control mode transition notification means), 41 ... Display unit 42, sound generation unit, L *, target operation amount, Wfl, Wfr, left and right front wheels, Wrl, Wrr, left and right rear wheels, S12, S14, mode transition means, S16, forced control mode transition notification means, S18, target operation Quantity calculating means, S20, S26, S28 ... Actuator operating means, S22 ... Operating speed limiting means, S24 ... Vehicle state determining means, S30 ... Forced control end means, S32 ... Forced control Stop means, S34 ... stop notification unit, T ... fault diagnosis tool

Claims (12)

  In a wheel turning device comprising a turning actuator for turning left and right rear wheels, a steering handle for turning left and right front wheels, and a control means for controlling the operation of the turning actuator,
  The control means includes
  Mode transition means for setting a control mode for controlling the operation of the steering actuator by an external signal input to a forced control mode for controlling the operation of the steering actuator so that the steering actuator returns to a neutral position; ,
  Based on the operation amount of the steering wheel in the steering wheel operation performed during the forced control mode, a target operation amount that is an operation amount required for the turning actuator to return to the neutral position in the forced control mode is calculated. Target operating amount calculating means;
  Actuator operating means for operating the steering actuator by the target operation amount during the forced control mode;
  A wheel turning device comprising: In the wheel steering apparatus according to claim 1 ,
The target operation amount calculating means calculates the target operation amount based on setting means in which a relationship between the operation amount of the steering handle and the target operation amount in a steering wheel operation performed during the forced control mode is set in advance. A wheel turning device characterized by calculating. In the wheel steering apparatus according to claim 2 ,
A steering wheel operation performed during the forced control mode is an operation for returning the steering handle from an operation position at which a current position of the steering actuator can be estimated to a neutral position. In the wheel steering apparatus according to claim 2 ,
The current position of the steering actuator is estimated in advance,
The wheel steering device according to claim 1, wherein an operation amount of the steering wheel in a steering wheel operation performed during the forced control mode is determined based on an estimated current position. In the wheel steering device according to any one of claims 1 to 4 ,
The wheel steering apparatus according to claim 1, wherein the control means further includes forced control end means for ending the forced control mode when the steering actuator is operated by the target operation amount. In the wheel steering apparatus according to any one of claims 1 to 5 ,
The control means includes
Vehicle state determination means for determining whether the vehicle state is a predetermined state during the forced control mode;
Forced control stopping means for stopping the forced control mode when the vehicle state is determined to be a predetermined state by the vehicle state determining means;
A wheel steering apparatus further comprising: In the wheel steering apparatus according to claim 6 ,
The wheel turning apparatus, further comprising stop notification means for notifying the stop of the forced control mode by the forced control stop means. In the wheel steering device according to any one of claims 1 to 7 ,
A wheel turning apparatus, further comprising forced control mode transition notifying means for notifying that a control mode for controlling the operation of the steering actuator by the control means has shifted to the forced control mode. In the wheel steering apparatus according to any one of claims 1 to 8 ,
The wheel steering apparatus according to claim 1, wherein the control means further includes an operation speed limiting means for limiting an operation speed of the steering actuator that operates during the forced control mode to a predetermined speed or less.   A steering actuator neutral position return method for returning a steering actuator for steering left and right rear wheels of a vehicle to a neutral position,
  A current position estimating step for estimating a current position of the steering actuator;
  By inputting an external signal to the control means for controlling the operation of the steering actuator, the control means changes the control mode for controlling the operation of the steering actuator from the current position to the neutral position. A mode transition step for setting the forced control mode to control the operation of the steering actuator so as to return; and
  A steering handle operating step for operating a steering handle for steering left and right front wheels;
  Setting means in which a relationship between an operation amount of the steering wheel operated in the steering wheel operation step and a target operation amount that is an operation amount necessary for operating the steering actuator from a current position to a neutral position is set in advance. On the basis of the target operation amount calculation step in which the control means calculates the target operation amount,
  A neutral position return step for returning the steered actuator to a neutral position by actuating the steered actuator by the actuating amount calculated in the target actuating amount calculating step;
  The neutral position return method of the steering actuator including In the steering actuator neutral position return method according to claim 10 ,
The current position estimating step is a step of estimating the current position by operating the steering handle to linearly travel the vehicle in an oblique direction so that the front wheel turning angle and the rear wheel turning angle coincide with each other.
The steered actuator neutral position return method, wherein the steering handle operating step is a step of operating the steering handle so that the vehicle returns to the neutral position from the operation position in a state where the vehicle can travel in a straight line. In the turning actuator neutral position return method according to claim 10 ,
The current position estimating step is a step in which an operator measures the current position of the steered actuator using a measuring device,
In the steering handle operation step, an operator investigates the operation amount of the steering handle corresponding to the target operation amount set by the setting means based on the current position measured in the current position estimation step, A steering actuator neutral position return method characterized in that the step is a step in which an operator operates the steering handle by the investigated operation amount.

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