JP4803338B2 - Vehicle steering device - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a vehicle steering apparatus capable of changing a ratio between an operation amount of an operation member and a steering amount of a wheel according to a variable representing a traveling state of the vehicle.
[0002]
[Prior art]
When transmitting the movement of the electric actuator to the wheel so that the rudder angle changes, the electric actuator is controlled according to the variable representing the running state of the vehicle, so that the operation amount of the operation member and the wheel according to the variable There has been proposed a vehicle steering device that changes a ratio with the amount of steering. Such steering devices include those that mechanically connect the operating member to the wheels and those that do not. When the operation member is mechanically connected to the wheel, for example, the rotation of the input shaft according to the operation of the steering wheel is transmitted to the output shaft through the planetary gear mechanism, and the ring gear constituting the planetary gear mechanism is driven in the transmission. It is known to change the ratio between the operation amount and the turning amount by controlling the electric actuator according to the vehicle speed. In addition, when the operating member is not mechanically connected to the wheel, the steering angle of the electric actuator is changed according to the movement of the electric actuator without mechanically connecting the operating member imitating the steering wheel to the wheel. It is known that the ratio between the operation amount and the steered amount is changed by transmitting to the wheel and controlling the electric actuator according to the vehicle speed, the yaw rate, etc. at the time of the transmission.
[0003]
In the steering apparatus as described above, when the operation amount of the operation member is detected by a sensor and the detected operation amount from the neutral position of the operation member is equal to or less than the set amount, the electric actuator is controlled so that the turning amount of the wheel does not change. Control is carried out (Japanese Patent Publication No. 7-11822, Japanese Patent Publication No. 7-11824). As a result, a dead zone in which the rudder angle does not change with respect to the operation is provided in the vicinity of the neutral position of the operation member, and the traveling stability during straight traveling of the vehicle is improved.
[0004]
[Problems to be solved by the invention]
In the conventional steering device provided with the dead zone as described above, the steering angle changes if the neutral position of the operation member is a reference position and the operation amount of the operation member from the reference position is equal to or less than a set amount. Absent. Therefore, the play amount of operation of the operation member can be appropriately obtained when the vehicle goes straight. However, when running on a road curved with a constant curvature or a bank road inclined by snow, etc. while maintaining a constant rudder angle, if the neutral position of the operation member is the reference position, the play amount of operation of the operation member is reduced. It cannot be obtained properly. For example, FIG. 10 shows a relationship between the operation amount θi from the neutral position of the conventional operation member and the magnitude of the steering angle θo corresponding to the wheel turning amount, and the play amount of the operation is based on the neutral position of the operation member as a reference position. Is equal to θp during left steering and during right steering. In a state where the vehicle is turning counterclockwise while maintaining a certain operation amount θa slightly larger than the play amount θp, the steering angle θ changes by only slightly operating the operation member by the driver. There is a problem that cannot be secured. Further, when the driver operates the operating member in the right direction from that state, the steering angle does not change even if the operating member is operated to enter the dead zone. That is, the vehicle behavior differs between when the operation member is operated to the right and when the operation member is operated to the left from a state in which the constant operation amount θa is maintained. Therefore, there is a problem that the driver feels uncomfortable at the time of steering.
[0005]
It is an object of the present invention to provide a vehicle steering apparatus that can solve the above problems.
[0006]
[Means for Solving the Problems]
The present invention includes an operation member, a sensor for detecting an operation amount of the operation member, a means for determining whether or not a detected operation amount from a reference position of the operation member exceeds a set amount, an electric actuator, A control device for an electric actuator, a mechanism capable of transmitting the movement of the electric actuator to a wheel so that the rudder angle changes, and a sensor for detecting a variable representing a running state of the vehicle, and a detection operation from the reference position When the amount exceeds the set amount, the electric actuator is controlled so that the ratio between the operation amount of the operation member and the turning amount of the wheel changes according to the detected variable, and the detected operation amount from the reference position is set to the set amount. In the vehicle steering apparatus in which the electric actuator is controlled so that the steering amount of the wheel does not change when the following is true, a means for determining whether or not the steering is in a steady state for a set time or more The neutral position of the operating member is set as the reference position when it is not in a steady steering state for a set time or more, and when it is in a steady steering state for a set time or more, in the steady steering state for a set time or more. The center position of the operating range of the operating member is the reference position.When the change in the detected operation amount is less than the set value for the set time or more, it is determined that the steady steering state is set for the set time or more.It is characterized by that.
According to the present invention, when the steering wheel is in the steady steering state for the set time or longer, the center position of the operating range of the operating member in the steady steering state for the set time or longer is set as the reference position. When the detected operation amount from the reference position is equal to or less than the set amount, the electric actuator is controlled so that the wheel turning amount does not change. As a result, when the vehicle is traveling while maintaining a certain rudder angle, play can be provided for the operation of the operation member, and the play amount can be made equal between left steering and right steering.Further, it can be easily determined whether or not the driver is operating within the range of play without intention of steering.
[0007]
It is preferable that a sensor for detecting the operating force of the operating member is provided, and it is determined that the steering is not in a steady state when the detected operating force is equal to or less than a set value.
Since the operating force of the operating member increases as the steering angle increases, it can be determined whether or not the operating member is being operated when the steering angle is zero based on whether or not the operating force of the operating member is equal to or less than a set value. Therefore, when the detected operating force is equal to or less than the set value, it is determined that the steering member is not in a steady steering state. When the operating member is operated at a steering angle of zero, the neutral position of the operating member is used as a reference position. The amount can be made equal between left steering and right steering.
[0009]
The input shaft that rotates according to the operation of the operation member, the output shaft, the rotation transmission mechanism that transmits the rotation of the input shaft to the output shaft, and the rotation of the output shaft is transmitted to the wheels so that the steering angle changes. It is preferable that the movement of the electric actuator is transmitted to the wheel so that the steering angle changes by driving the components of the rotation transmission mechanism by the electric actuator.
Thus, the present invention can be applied to a vehicle steering apparatus in which an operation member and wheels are mechanically coupled.
The rotation transmission mechanism is constituted by a planetary gear mechanism that holds a planetary gear meshing with a sun gear and a ring gear by a carrier, and the first planetary gear element that is one of the sun gear, the ring gear, and the carrier is connected to the input shaft. A second planetary gear element that is not connected to the input shaft among the sun gear, ring gear, and carrier is connected to the output shaft, and is connected to the input / output shaft in the sun gear, ring gear, and carrier. Preferably, the third planetary gear element that is not rotated is driven to rotate by the electric actuator.
[0010]
Preferably, the movement of the electric actuator is transmitted to the wheel such that the steering angle changes in accordance with the movement without mechanically connecting the operating member to the wheel. Thus, the present invention can be applied to a vehicle steering apparatus that transmits the movement of the electric actuator to the wheel so that the steering angle changes in accordance with the movement without mechanically connecting the operation member to the wheel.
[0011]
DETAILED DESCRIPTION OF THE INVENTION
A vehicle steering apparatus 1 according to the first embodiment shown in FIG. 1 includes an input shaft 2 connected to a steering wheel (operation member) H. The input shaft 2 is supported by the housing 10 via bearings 7 and 8.
[0012]
The rotation of the input shaft 2 according to the operation of the steering wheel H is transmitted to the output shaft 11 via the planetary gear mechanism (rotation transmission mechanism) 30. The output shaft 11 is disposed coaxially with the input shaft 2 via a gap, and is supported by the housing 10 via bearings 12 and 13. The rotation of the output shaft 11 is transmitted to the wheels so that the steering angle is changed by the steering gear. As the steering gear, known ones such as a rack and pinion type steering gear and a ball screw type steering gear can be used. Thereby, the rotation of the input shaft 2 is transmitted to the output shaft 11 via the planetary gear mechanism 30, and the steering angle changes due to the rotation of the output shaft 11.
[0013]
The planetary gear mechanism 30 holds a planetary gear 33 that meshes with a sun gear 31 and a ring gear 32 by a carrier 34. The sun gear 31 is connected to the end portion of the input shaft 2 so as to rotate together. The carrier 34 is coupled to the output shaft 11 so as to rotate together. The ring gear 32 is fixed to a holder 36 surrounding the input shaft 2 via bolts 362. The holder 36 is supported via a bearing 9 by a cylindrical member 35 fixed to the housing 10 so as to surround the input shaft 2. A worm wheel 37 is fitted on the outer periphery of the holder 36 so as to rotate together. A worm 38 that meshes with the worm wheel 37 is supported by the housing 10. The worm 38 is driven by a motor (electric actuator) 39 attached to the housing 10. Thereby, the ring gear 32 which is a component of the planetary gear mechanism 30 is driven by the motor 39, and the movement of the motor 39 is transmitted to the wheels so that the steering angle changes.
[0014]
As the motor 39, for example, a brushed DC motor that is pulse-width-modulated and driven according to a target drive current is used. When the movement of the motor 39 is transmitted to the wheels so that the rudder angle changes, the motor 39 is controlled from the input shaft 2 according to the variable by performing closed loop control according to the variable representing the running state of the vehicle. The rotation transmission ratio to the shaft 11, that is, the ratio between the operation amount of the steering wheel H and the turning amount of the wheel can be changed. In the present embodiment, the variable representing the running state is the vehicle speed. For example, by controlling the motor 39 so that the rotational angular velocity of the input shaft 2 is equal to the rotational angular velocity of the ring gear 32 in a stationary state where the vehicle speed is zero, the rotational transmission ratio from the input shaft 2 to the output shaft 11 is 1. To do. Further, the rotational angular velocity of the ring gear 32 is decreased as the speed is increased, and the planetary gear mechanism 30 is caused to function as a reduction gear mechanism, whereby the turning performance at low speed and the running stability at high speed can be improved.
[0015]
As shown in FIG. 2, the motor 39 is connected to a control device 40 mounted on the vehicle, and a vehicle speed sensor 41 is connected to the control device 40 as a variable detection sensor representing a running state. Further, the control device 40 includes a steering angle sensor 42 that detects a rotation angle of the input shaft 2 as an operation amount of the steering wheel H, and a rotation angle sensor 43 that detects a rotation angle of the output shaft 11 as a steering amount of a wheel. Is connected. The control device 40 performs the closed loop control of the motor 39 so as to reduce the deviation between the detected target turning amount obtained from the rotation angle and vehicle speed of the input shaft 2 and the detected rotation angle of the output shaft 11. Further, a torque sensor 44 that detects a steering torque transmitted by the input shaft 2 as an operation force that the driver acts on the steering wheel H is connected to the control device 40.
[0016]
FIG. 3 is a control block diagram of a control system in the steering device 1. 3, Ti is the steering torque of the steering wheel H, V is a value detected by the vehicle speed sensor 41, θi is a value detected by the rudder angle sensor 42 of the rotation angle of the input shaft 2, and θo is the rotation angle of the output shaft 11. Detection value by angle sensor 43, θo^* Is the target rotation angle of the output shaft 11, i^* Is a target drive current which is a target control amount of the motor 39, C1 is a target rotation angle θo of the output shaft with respect to the rotation angle θi of the input shaft 2.^* Adjusting part C2 is the target rotation angle θo of the output shaft 11^* And the rotation angle θo (θo^* Target drive current i of the motor 39 with respect to -θo)^* It is the adjustment part.
[0017]
The control device 40 detects the target rotation angle θo of the output shaft 11 with respect to the rotation angle θi of the input shaft 2 detected by the steering angle sensor 42.^* Is calculated based on a predetermined and stored relationship. In the present embodiment, the target rotation angle θo of the output shaft with respect to the rotation angle θi of the input shaft 2.^* The adjusting portion C1 is a proportional control element, and the target rotation angle of the output shaft 11 is θo.^* = K (V) · θi. Here, K (V) is a proportional gain and is a function of the vehicle speed V. The rotation angle θi of the input shaft 2, the vehicle speed V, and the target rotation angle θo of the output shaft 11.^* The proportional gain K (V) representing the relationship is stored in the control device 40. For example, as shown in FIG. 4, the proportional gain K (V) decreases as the vehicle speed V increases, and this relationship is stored in the control device 40. The control device 40 determines the target rotation angle θo of the output shaft 11 based on the stored proportional gain K (V), the detected rotation angle θi of the input shaft 2 and the detected vehicle speed V.^* Is calculated.
[0018]
The control device 40 controls the target rotation angle θo of the output shaft 11.^* And the detected rotation angle θo (θo^* −θo) and the target drive current i of the motor 39^* Remember the relationship between In this embodiment, the deviation (θo^* Target driving current i with respect to -θo)^* The adjustment unit C2 is a proportional integral (PI) control element, and the target drive current i^* I^* = G · (θo^* -Θo). Here, G is a transfer function, for example, Kg is a gain, T is a time constant, and the transfer function G is G = Kg · [1 + 1 / (T · s)] so that PI control is performed, and the gain Kg and time constant T are set so that optimal control can be performed. The transfer function G is stored in the control device 40.
[0019]
The control device 40 determines whether or not it is in a steady steering state for a predetermined set time or more. In this embodiment, the magnitude of the detected steering torque Ti corresponding to the operating force of the steering wheel H exceeds a predetermined set value, and the change in the detected rotation angle θi of the input shaft 2 corresponding to the operation amount is set time. When the amount is less than the predetermined set amount over the above, it is determined that the vehicle is in the steady steering state over the set time. Otherwise, it is determined that the vehicle is not in a steady steering state. The set value of the operating force may be determined so as to correspond to the force required to steer the wheel. The set amount of the change in the operation amount can be determined so as to correspond to the play amount of the steering wheel H, for example, several degrees. The set time can be determined so as to correspond to the time required for the vehicle to pass through the road curved with a constant curvature, and is set to several seconds, for example. In order to determine whether or not the change in the detected rotation angle θi is less than the set value over a set time, the control device 40 of the present embodiment sets the change speed d (θi) / dt of the rotation angle θi detected in time series. It is calculated, and it is determined whether the magnitude of the change speed d (θi) / dt is less than the set speed over a set time. Thereby, it can be easily determined whether or not the driver is operating the steering wheel H within the range of play without intention of steering.
[0020]
The control device 40 determines whether or not the change in the detected rotation angle θi from the reference position of the steering wheel H exceeds a predetermined set amount. The set amount of the change in the operation amount may be determined so as to correspond to the play range. In this determination, when the steering wheel H is not in the steady steering state for the set time or longer, the neutral position of the steering wheel H is set as the reference position. When the steering wheel H is in the steady steering state for the set time or longer, the steady steering state for the set time or longer. The center position of the operation range of the steering wheel H at is the reference position. The neutral position of the steering wheel H can be obtained by initial setting so that the detected value of the steering angle sensor 42 becomes zero when the steering wheel H is in the neutral position. In the present embodiment, the center position of the operation range of the steering wheel H in the steady steering state over the set time is divided by the number of samplings of the detected rotation angle θi sampled at regular time intervals over the set time. To find out.
[0021]
When the detected rotation angle θi from the reference position exceeds the set amount, the control device 40 changes the ratio of the operation amount of the steering wheel H and the turning amount of the wheel according to the detected vehicle speed V. Control to do. That is, the stored transfer function G and the calculated target rotation angle θo of the output shaft 11^* And the target drive current i of the motor 39 based on the detected rotation angle θo^* And the calculated target drive current i^* Is applied to drive the motor 39. Further, the control device 40 controls the motor 39 so that the turning amount of the wheel does not change when the detected rotation angle θi from the reference position is equal to or less than the set amount.
[0022]
The control procedure by the control device 40 will be described with reference to the flowchart of FIG. First, the detection values of the sensors 41, 42, 43 are read (step 1). Next, it is determined whether or not the magnitude of the detected steering torque Ti exceeds the set value To (step 2), and if it exceeds the set value To, the change speed d (θi) / dt of the detected rotation angle θi of the input shaft. (Step 3), and if it is less than the set speed A, the time is accumulated (step 4), and the detected rotation angle θi of the sampled input shaft is accumulated (step 4). Step 5), it is determined whether or not the integration time t is equal to or longer than the set time ta (step 6). If the accumulated time t is less than the set time ta in step 6, the process returns to step 1. If the accumulated time t is equal to or longer than the set time ta in step 6, it is determined that the steering is in a steady state over the set time and the sampled integrated value Σθi of the detected rotation angle θi of the input shaft 2 is divided by the sampling number n. The center position of the operation range of the steering wheel H thus obtained is set as a reference position θs (step 7). When the magnitude of the detected steering torque Ti is less than or equal to the set value To in step 2, and when the magnitude of the change speed d (θi) / dt of the detected rotation angle θi of the input shaft 2 is greater than or equal to the set speed A in step 3 The time integration and the integration of the detected rotation angle θi of the input shaft are canceled (step 8), and the neutral position of the steering wheel H is set as the reference position θs (step 9). Next, it is determined whether or not the magnitude of the detected rotation angle θi of the input shaft 2 from the determined reference position θs exceeds the set amount θp (step 10). When the magnitude of the detected rotation angle θi from the reference position θs exceeds the set amount θp in step 10, a proportional gain K (V) corresponding to the detected vehicle speed V is obtained (step 11), and the obtained proportional gain K (V ) And the detected rotation angle θi of the input shaft 2, the target rotation angle θo of the output shaft 11.^* (Step 12), and the target rotation angle θo^* And the detected rotation angle θi of the output shaft 11 (θo^* −θo) and the transfer function G, the target drive current i^* (Step 13) and the target drive current i^* Based on the above, the motor 39 is driven (step 14). Next, whether or not to end the control is determined by, for example, whether or not the ignition switch of the vehicle is on (step 15). If not, the process returns to step 1. When the magnitude of the detected rotation angle θi from the reference position θs is equal to or smaller than the set amount θp in step 10, the target rotation angle θo of the output shaft 11 is prevented so that the steering angle does not change.^* Is the same as the immediately preceding value and does not change (step 16).
[0023]
According to the first embodiment, in a vehicle in which the steering wheel H and the wheels are mechanically connected, when the vehicle is in the steady steering state for the set time ta or longer, the vehicle is in the steady steering state for the set time ta or longer. When the central position of the operation range of the steering wheel H is the reference position θs, and the magnitude of the detected rotation angle θi of the input shaft 2 from the reference position θs is equal to or less than the set amount θp, the wheel turning amount does not change. Thus, the motor 39 is controlled. As a result, when the vehicle is traveling in a state where a certain steering angle is maintained, play can be provided in the operation of the steering wheel H, and the play amount can be made equal between left steering and right steering. Further, when the steering wheel H is not in the steady steering state for the set time ta or more, the play amount of the operation of the steering wheel H can be made equal between the left steering and the right steering with the neutral position of the steering wheel H as the reference position. . FIG. 6 shows the relationship between the detected rotation angle θi of the input shaft 2 corresponding to the operation amount from the neutral position of the steering wheel H and the magnitude of the steering angle θ corresponding to the wheel turning amount over the set time ta. A solid line indicates when the vehicle is not in the steady steering state, and a broken line indicates when the vehicle is in the steady steering state over the set time ta. That is, when the midpoint position of the dead zone in which the steering angle does not change in response to the operation of the steering wheel H is not in the steady steering state for the set time ta or longer, it becomes the neutral position of the steering wheel H and steady for the set time ta or longer. When the vehicle is in the steering state, it is offset to the center position θa of the operation range of the steering wheel H. Further, whether or not the steering wheel H is being operated when the steering angle is zero can be determined based on whether or not the operating force of the steering wheel H is equal to or less than the set value. Therefore, when the detected steering torque Ti is less than or equal to the set value To, it is determined that the steering wheel H is not in a steady steering state. As a reference position, the play amount of operation can be made equal between left steering and right steering.
[0024]
FIG. 7 shows a vehicle steering apparatus employing a so-called steer-by-wire system according to a second embodiment of the present invention. The vehicle steering apparatus includes an operation member 101 simulating a steering wheel, a steering motor (electric actuator) 102 driven by a rotation operation of the operation member 101, and the movement of the steering motor 102. A steering gear 103 is provided that transmits the steering wheel 101 to the front left and right wheels 104 so that the rudder angle changes without mechanically connecting the wheel 101 to the wheel 104. The steering motor 102 can be constituted by an electric motor such as a known brushless motor. The steering gear 103 has a motion conversion mechanism that converts the rotational motion of the output shaft of the steering motor 102 into the linear motion of the steering rod 107. The movement of the steering rod 107 is transmitted to the wheel 104 via the tie rod 108 and the knuckle arm 109, and the toe angle of the wheel 104 changes. A known gear can be used as the steering gear 103, and the configuration is not limited as long as the movement of the steering motor 102 can be transmitted to the wheels 104 so that the steering angle changes. In the state where the steering motor 102 is not driven, the wheel alignment is set so that the wheel 104 can return to the straight steering position by the self-aligning torque. The operating member 101 is connected to a rotating shaft 110 that is rotatably supported by the vehicle body side. The output shaft of the operating actuator 119 is integrated with the rotating shaft 110. The operation actuator 119 can be constituted by an electric motor such as a brushless motor. An elastic member 130 is provided that provides elasticity in a direction to return the operation member 101 to the straight steering position.
[0025]
An angle sensor 111 that detects the rotation angle of the rotary shaft 110 as a sensor for detecting the operation amount of the operation member 101, a torque sensor 112 that detects an operation torque corresponding to the operation force of the operation member 101, and a detection of the turning amount. A steering angle sensor 113 that detects a steering angle as a sensor, a speed sensor 114 that detects a vehicle speed, and a yaw rate sensor 116 that detects a yaw rate of the vehicle are provided as variables for detecting a running variable. The angle sensor 111, the torque sensor 112, the rudder angle sensor 113, the speed sensor 114, and the yaw rate sensor 116 are connected to a control device 120 configured by a computer.
[0026]
The control device 120 performs closed-loop control of the steering motor 102 via the drive circuit 122 according to the vehicle speed and the yaw rate when transmitting the movement of the steering motor 102 to the wheels 104 so that the steering angle changes. Thus, the ratio between the operation amount of the operation member 101 and the turning amount of the wheel 104 is changed according to the vehicle speed and the yaw rate.
[0027]
FIG. 8 is a block diagram showing the configuration of the control system of the control device 120 of the second embodiment. Here, γ is a detected value of the yaw rate of the vehicle 100, γ^* Is the target value of the yaw rate, V is the detected value of the vehicle speed, δh is the detected value of the rotation angle of the operating member 101, δ is the detected value of the steering angle, and δ^* Is the target rudder angle, i^* Is the target value of the drive current of the steering motor 102, G1 is γ with respect to δh^* The transfer function of the control unit, G2 is γ^* Δ for the deviation between γ and γ^* The transfer function of the adjusting part of G3, G3 is δ^* I for the deviation between δ and δ^* It is a transfer function of the adjustment part.
Δ obtained from the detected δh, V, γ^* Then, the steering motor 102 is closed-loop controlled so as to reduce the deviation from the detected δ. That is, γ with respect to δh^* For example, the adjustment unit is a proportional control element, the proportional gain is proportional to the vehicle speed V, and the following relationship is stored in the control device 120, where K is a proportionality constant.
γ^* = G1 · δh = K · V · δh
That γ^* Δ for the deviation between γ and γ^* For example, the adjusting unit is a PI control element, and the following relationship is stored in the control device 120 with Ka as a gain and Ta as a time constant.
δ^* = G2 · (γ^* −γ) = Ka [1 + 1 / (Ta · s)] (γ^* −γ)
That δ^* I for the deviation between δ and δ^* For example, the adjusting unit is a PI control element, and the following relationship is stored in the control device 120 with Kb as a gain and Tb as a time constant.
i^* = G3 · (δ^* −δ) = Kb [1 + 1 / (Tb · s)] (δ^* −δ)
The proportionality constant K, the gains Ka and Kb, and the time constants Ta and Tb are appropriately adjusted so that optimum control can be performed.
[0028]
K1 is the target operating torque Th with respect to the rotation angle δh of the operating member 101.^* Gain, and Th stored in advance^* = Target operation torque Th from the relationship of K1 · δh and the rotation angle δh detected by the angle sensor 111^* Is calculated. The gain K1 is adjusted so that optimal control can be performed.
G4 is the target operation torque Th^* Target operating current ih of the operating actuator 119 with respect to the deviation between the operating torque Th and the operating torque Th^* Is the transfer function. The control device 120 has previously stored ih^* = G4 ・ (Th^* -Th) and the calculated target operation torque Th^* And the target driving current ih from the operation torque Th detected by the torque sensor 112^* Is calculated. For example, when the PI control is performed, the transfer function G4 is G4 = K4 [1 + 1 / (τa · s)] where the gain is K4, the Laplace operator is s, and the time constant is τa. The gain K4 and time constant τa are adjusted so that optimum control can be performed. The target drive current ih^* Accordingly, the operation actuator 119 is driven. Thereby, the operation reaction force according to the steering resistance acting on the wheel 104 from the road surface can be generated by the operation actuator 119.
[0029]
The control device 120 determines whether or not it is in a steady steering state over a set time. In the present embodiment, the magnitude of the detected operation torque Th corresponding to the operation force of the operation member 101 exceeds a predetermined set value, and the change in the detected rotation angle δh of the operation member 101 corresponding to the operation amount is predetermined. When the value is less than the set value for the set time or longer, it is determined that the steering state is steady for the set time or longer. Otherwise, it is determined that the vehicle is not in a steady steering state. The set value of the operating force may be determined so as to correspond to the force required to steer the wheel. The set value of the change in the operation amount can be determined so as to correspond to the play amount of the operation member 101, for example, several degrees. The set time can be determined so as to correspond to the time required for the vehicle to pass through the road curved with a constant curvature, and is set to several seconds, for example. In order to determine whether or not the change in the detected rotation angle δh is less than the set value over the set time, the control device 120 of the present embodiment sets the change speed d (δh) / dt of the detected rotation angle δh in time series. It is calculated, and it is determined whether the magnitude of the change speed d (δh) / dt is less than the set speed over the set time. Thereby, it can be easily determined whether or not the driver is operating the operation member 101 within the range of play without intention of steering.
[0030]
The control device 120 determines whether or not the change in the detected rotation angle δh from the reference position of the operation member 101 exceeds a predetermined set amount. The set amount of change in the operation amount of the operation member 101 is determined so as to correspond to the play range of the operation. In this determination, when the steering is not in a steady state for a set time or longer, the neutral position of the operation member 101 is set as the reference position. The neutral position of the operation member 101 can be obtained by initial setting so that the detection value of the angle sensor 111 becomes zero when the operation member 101 is in the neutral position. When the vehicle is in the steady steering state for the set time or longer, the center position of the operation range of the operation member 101 in the steady steering state for the set time or longer is set as the reference position. In this embodiment, the central position of the operation range of the operation member 101 in the steady steering state over the set time is divided by the number of samplings of the detected rotation angle δh sampled at regular time intervals over the set time. To find out.
[0031]
When the magnitude of the detected rotation angle δh from the reference position exceeds the set amount, the control device 120 causes the motor 102 to change the operation amount of the operation member 101 and the wheel turning amount according to the detected vehicle speed V and the detected yaw rate γ. The ratio is controlled so as to change. That is, the target drive current i of the motor 102 is based on the stored transfer function G3.^* And the calculated target drive current i^* Is applied to drive the motor 102. Further, the control device 120 controls the motor 102 so that the wheel turning amount does not change when the detected rotation angle δh from the reference position is equal to or less than the set amount.
[0032]
A control procedure by the control device 120 of the second embodiment will be described with reference to the flowchart of FIG. First, the detection value by each sensor is read (step 101). Next, from the detected rotation angle δh of the operation member 101, the target operation torque Th^* Th^* = Calculated from the relationship of K1 · δh, and remembered Th^* And the detected operation torque Th, the target drive current ih of the operation actuator 119^* Ih^* = G4 ・ (Th^* -Th), the target drive current ih^* Accordingly, the operation actuator 119 is driven (step 102). Next, it is determined whether or not the magnitude of the detected operation torque Th exceeds the set value To (step 103). If it exceeds the set value To, the change speed d (δh) / of the detected rotation angle δh of the operation member 101 is determined. It is determined whether or not the magnitude of dt is less than the set speed A (step 104). If it is less than the set speed A, the time is accumulated (step 105), and the detected rotation angle δh of the sampled operation member 101 is accumulated. (Step 106), it is determined whether or not the accumulated time t is equal to or longer than the set time ta (step 107). If the accumulated time t is less than the set time ta in step 107, the process returns to step 101. If the accumulated time t is greater than or equal to the set time ta in step 107, it is determined that the vehicle is in the steady steering state for the set time or longer, and the accumulated value Σδh of the detected rotation angle δh of the operating member 101 is divided by the sampling number n. The central position δs of the operation range of the operation member 101 obtained in this way is set as the reference position (step 108). When the magnitude of the detected operation torque Th is equal to or less than the set value To in step 103, the magnitude of the change speed d (δh) / dt of the detected rotation angle δh of the operation member 101 is equal to or greater than the set speed A in step 104 The time integration and the integration of the detected rotation angle δh of the input shaft are canceled (step 109), and the neutral position of the operation member 101 is set as the reference position δs (step 110). Next, it is determined whether or not the detected rotation angle δh of the operation member 101 from the obtained reference position δs exceeds the set amount δp (step 111). When the detected rotation angle δh exceeds the set amount δp in step 111, the target yaw rate γ corresponding to the detected rotation angle δh and the vehicle speed V is determined.^* Is calculated from the stored relationship (step 112), and the target yaw rate γ^* And the target rudder angle δ corresponding to the deviation from the detected yaw rate γ^* Is calculated from the stored relationship (step 113), and the target steering angle δ is calculated.^* And the target drive current i of the steering motor 102 corresponding to the deviation between the detected steering angle δ and^* Is calculated from the stored relationship (step 114), and the target drive current i is calculated.^* Accordingly, the steering motor 102 is driven (step 115). Next, whether or not to end the control is determined, for example, based on whether or not the ignition switch of the vehicle is on (step 116). If not, the process returns to step 101. In step 111, when the magnitude of the detected rotation angle δh of the operation member 101 from the reference position δs is equal to or less than the set amount δp, the target rudder angle δ is set so that the rudder angle does not change.^* Is the same as the immediately preceding value and does not change (step 117), and then step 114 is reached.
[0033]
According to the said 2nd Embodiment, the effect similar to 1st Embodiment can be show | played in the vehicle in which the operation member 101 and the wheel are not mechanically connected.
[0034]
The present invention is not limited to the above embodiment. For example, in each of the above embodiments, a sensor that detects the operating force of the operating member is provided, and when the detected operating force is equal to or less than a set value, it is determined that the steering state is not in a steady state. If the change in the detected operation amount is less than the set value over the set time, the steady steering state may be determined over the set time. In the first embodiment, the operation amount of the steering wheel H is used as a variable representing the running state of the vehicle, and the motor 39 is replaced with the vehicle speed or according to the operation amount of the steering wheel H detected by the steering angle sensor 42 together with the vehicle speed. You may make it control. When the operation amount is large, the turning performance of the vehicle can be improved by increasing the rotation transmission ratio from the input shaft 2 to the output shaft 11 than when the operation amount is small. Further, the ring gear 32 or the carrier 34 of the planetary gear mechanism 30 is connected to the input shaft 2 in the first embodiment, and the constituent elements of the planetary gear mechanism 30 connected to the output shaft 11 are not connected to the input shaft 2. Alternatively, the ring gear 32 may be used, and the constituent elements of the planetary gear mechanism 30 driven by the motor 39 may be the sun gear 31 or the carrier 34 that is not connected to the input / output shafts 2 and 11. That is, any one of the planetary gear elements of the sun gear 31, the ring gear 32, and the carrier 34 is connected to the input shaft 2, and any of the planetary gear elements that are not connected to the input shaft 2 is connected to the output shaft 11. The planetary gear elements connected to each other and not connected to the input / output shaft may be rotationally driven by the motor 39. Further, a rotation transmission mechanism other than the planetary gear mechanism 30, for example, a planetary cone type rotation transmission mechanism may be used. Further, in each embodiment, when the electric actuator is controlled according to the variable representing the running state of the vehicle, the ratio between the operation amount of the operation member and the steering amount of the wheel can be changed according to the variable. For example, the configuration of the control system is not particularly limited.
[0035]
【The invention's effect】
According to the present invention, when a vehicle capable of changing the ratio between the operation amount of the operation member and the steering amount of the wheel is driven while maintaining a constant rudder angle, a certain play range for operation of the operation member can be changed. It is possible to provide a vehicle steering apparatus that is provided in any direction and does not give the driver a sense of incongruity during steering.
[Brief description of the drawings]
FIG. 1 is a longitudinal sectional view of a steering apparatus according to a first embodiment of the present invention.
FIG. 2 is an explanatory diagram of a control configuration of the steering device according to the first embodiment of the present invention.
FIG. 3 is a block diagram of a control system in the steering apparatus according to the first embodiment of the present invention.
FIG. 4 is a diagram showing an example of a relationship between a proportional gain K (V) and a vehicle speed V in the control system of the steering apparatus according to the first embodiment of the present invention.
FIG. 5 is a flowchart showing a control procedure in the steering apparatus according to the first embodiment of the present invention.
FIG. 6 is a diagram showing an example of the relationship between the detected rotation angle of the input shaft and the magnitude of the steering angle in the steering device according to the first embodiment of the present invention.
FIG. 7 is a diagram illustrating the configuration of a steering device according to a second embodiment of the invention.
FIG. 8 is a block diagram of a control system in a steering apparatus according to a second embodiment of the present invention.
FIG. 9 is a flowchart showing a control procedure in the steering apparatus according to the second embodiment of the present invention.
FIG. 10 is an explanatory diagram of problems of a conventional steering device
[Explanation of symbols]
2 Input shaft
11 Output shaft
30 Planetary gear mechanism
37 Worm wheel
38 Warm
39 Motor
40 Control device
41 Vehicle speed sensor
42 Rudder angle sensor
43 Rotation angle sensor
44 Torque sensor
101 Operation member
102 Steering motor
103 Steering gear
104 wheels
111 Angle sensor
112 Torque sensor
113 Rudder angle sensor
114 Speed sensor
116 Yaw rate sensor
120 controller
H Steering wheel

Claims (4)

An operation member;
A sensor for detecting an operation amount of the operation member;
Means for determining whether or not the detected operation amount from the reference position of the operation member exceeds a set amount;
An electric actuator;
A control device for the electric actuator;
A mechanism capable of transmitting the movement of the electric actuator to the wheel so that the rudder angle changes;
A sensor for detecting a variable representing the running state of the vehicle,
When the detected operation amount from the reference position exceeds the set amount, the electric actuator is controlled so that the ratio between the operation amount of the operation member and the turning amount of the wheel changes according to the detected variable,
In the vehicle steering apparatus in which the electric actuator is controlled so that the turning amount of the wheel does not change when the detected operation amount from the reference position is equal to or less than the set amount,
Means for determining whether or not the vehicle is in a steady steering state over a set time;
When not in a steady steering state for a set time or longer, the neutral position of the operation member is set as the reference position,
When it is in a steady steering state over a set time, the center position of the operation range of the operating member in the steady steering state over the set time is set as the reference position ,
A vehicle steering apparatus characterized in that when a change in a detected operation amount is less than a set value for a set time or more, the vehicle is determined to be in a steady steering state for a set time or more . A sensor for detecting the operation force of the operation member;
2. The vehicle steering apparatus according to claim 1, wherein when the detected operation force is equal to or less than a set value, it is determined that the vehicle is not in a steady steering state. An input shaft that rotates according to the operation of the operation member;
An output shaft;
A rotation transmission mechanism for transmitting the rotation of the input shaft to the output shaft;
A steering gear that transmits the rotation of the output shaft to the wheels so that the steering angle changes,
The vehicle steering apparatus according to claim 1 or 2 , wherein a component of the rotation transmission mechanism is driven by the electric actuator so that the movement of the electric actuator is transmitted to the wheel so that the steering angle changes. The vehicle steering apparatus according to claim 1 or 2 , wherein the movement of the electric actuator is transmitted to the wheel such that the steering angle changes in accordance with the movement without mechanically connecting the operation member to the wheel. .

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