Steering control device and steering control method

Abstract

To provide a steering control device and a steering control method that are able to reduce generation of reaction force causing a sense of incongruity to a driver.SOLUTION: A steering control device 10 includes: a detection unit 14 that detects a lane R in which an own vehicle travels; a reaction force device 16 that applies a reaction force in a steering direction of a steering wheel 2 for operating a steering device 4 of the own vehicle; and a control unit 12 that recognizes a position of the own vehicle in the lane, based on a detection result of the lane, and outputs the reaction force from the reaction force device in order to prevent the own vehicle from deviating from the lane. The control unit performs first control for applying the reaction force to the steering wheel by controlling the reaction force device, based on a detection result of a pair of first boundary W1 and second boundary W2 of the lane, in order to prevent the own vehicle from deviating from the first boundary, and limits the reaction force output from the reaction force device for a predetermined time, with a first timing at which a monitoring target of departure of the lane is switched from the first boundary to the second boundary.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to a steering control device and a steering control method that generate a reaction force on a steering wheel to maintain a vehicle in a lane.

Background Art

[0002] Patent Document 1 discloses a technique for applying a reaction force (auxiliary torque) to the rotation direction of a steering wheel so as to maintain a vehicle within a lane when the vehicle travels in a lane. This reaction force is applied in a direction in which the host vehicle moves away from the boundary line as the distance between the lateral position of the host vehicle and the boundary line of the lane decreases. In a road where the first lane and the second lane are adjacent to each other with respect to the boundary line, when the host vehicle travels in the first lane and changes lanes to the second lane, the reaction force is controlled. When the host vehicle approaches the boundary line in the first lane, the reaction force increases based on a predetermined decrease amount according to the distance from the boundary line.

[0003] After the host vehicle has crossed the boundary line, when the host vehicle moves away from the boundary line in the second lane, the reaction force is changed based on a predetermined decrease amount according to the distance from the boundary line. When the host vehicle crosses the boundary line, if the distance of the host vehicle from the boundary line is less than or equal to a predetermined value, the reaction force decreases based on a first decrease amount. If the distance of the host vehicle from the boundary line exceeds the predetermined value, the reaction force decreases based on a second decrease amount that is larger than the first decrease amount. When the direction of the reaction force is reversed, the reaction force decreases based on a third decrease amount until it matches the reaction force for preventing departure from the second lane.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] According to the technology described in Patent Document 1, when the direction of the reaction force reverses, the amount of change in the reaction force is switched, which may result in a reaction force occurring in a direction different from what the driver expected.

[0006] The present invention aims to provide a steering control device and a steering control method that can reduce the generation of reaction forces that cause discomfort to the driver. [Means for solving the problem]

[0007] A steering control device according to one aspect of the present invention includes: a detection unit for detecting the lane in which the vehicle is traveling; a reaction force device that applies a reaction force to the steering direction of the steering wheel for operating the steering device of the vehicle; and a control unit that recognizes the position of the vehicle in the lane based on the lane detection result and causes the reaction force to output from the reaction force device in order to prevent the vehicle from deviating from the lane. The control unit performs a first control to apply the reaction force to the steering wheel by controlling the reaction force device based on the detection result of a pair of first and second boundaries of the lane in order to prevent the vehicle from deviating from the first boundary, or a second control to apply the reaction force to the steering wheel by controlling the reaction force device in order to prevent the vehicle from deviating from the second boundary, and limits the reaction force output from the reaction force device for a predetermined period of time at a first timing when the target of lane departure monitoring is switched from the first boundary to the second boundary, or at a second timing when the target of lane departure monitoring is switched from the second boundary to the first boundary. [Effects of the Invention]

[0008] According to the present invention, it is possible to reduce the generation of reaction forces that cause discomfort to the driver. [Brief explanation of the drawing]

[0009] [Figure 1] This is a block diagram showing the configuration of a steering control device according to an embodiment of the present invention. [Figure 2] This is a diagram showing the lanes in which vehicles travel. [Figure 3] This figure shows the relationship between the amount of steering wheel movement and the limit of movement at which a reaction force is generated. [Figure 4] This diagram illustrates a first control mechanism that prevents a vehicle from deviating from the first lane boundary. [Figure 5] This diagram illustrates a second control mechanism that prevents a vehicle from deviating from the second lane boundary. [Figure 6] This diagram illustrates a control method for limiting reaction forces. [Figure 7] This is a flowchart showing the processing flow of the steering control method. [Modes for carrying out the invention]

[0010] As shown in Figure 1, the vehicle 1 comprises a steering system 4 for steering the wheels 6 and a steering control device 10 provided on the steering system 4. The steering system 4 is driven by the driver operating the steering wheel 2. The steering wheel 2 is connected to a steering shaft (not shown) for driving the steering system 4. The steering system 4 is equipped with a steering control device 10 for providing auxiliary torque in steering the wheels 6. The wheels 6 are, for example, a pair of front wheels provided on the vehicle 1. The wheels 6 are configured to be steerable about a rotation axis in the vertical direction. The wheels 6 are steered in the steering direction by the steering system 4. The wheels 6 may include a pair of steerable rear wheels.

[0011] The steering system 4 is, for example, a rack and pinion mechanism composed of a rack gear and a pinion gear. The pinion gear is rotationally driven by the steering shaft. The steering shaft is connected to the steering wheel 2. When the driver rotates the steering wheel 2, the pinion gear rotates via the steering shaft. The rack gear moves horizontally based on the rotation of the pinion gear, steering the wheels 6 via the linkage mechanism.

[0012] The steering system 4 may be configured as a Steering By Wire (SBW) system that drives the wheels 6 by motor in conjunction with the steering wheel 2. In this case, the steering wheel 2 and the steering system 4 do not need to be connected by a steering shaft. The steering system 4 may be configured with other devices as long as they can steer the wheels 6, in addition to the above configuration.

[0013] The steering control device 10 includes, for example, a reaction force device 16 that applies a reaction force to the steering device 4, a detection unit 14 that detects data necessary to adjust the amount of reaction force output, a control unit 12 that controls the reaction force device 16 based on the detection results detected by the detection unit 14, and a storage unit 18 that stores data and programs necessary for control.

[0014] The reaction force device 16 is configured to apply a reaction force to the steering direction of the steering wheel 2 in order to prevent the vehicle 1 from deviating from its lane, as described later. The reaction force device 16 may be composed of, for example, a power steering system that provides auxiliary torque to the operation of the steering wheel 2. The reaction force device 16 is controlled by the control unit 12. The reaction force device 16 is composed of, for example, a motor or a reduction gear. The reaction force device 16 is configured to apply auxiliary torque to the rotation direction of the steering shaft.

[0015] The reaction force device 16 is configured to apply a reaction force in the direction of rotation opposite to the direction of rotation of the steering shaft by reducing the auxiliary torque applied to the direction of rotation of the steering shaft when preventing the vehicle 1 from deviating from its lane. If the steering system 4 is equipped with a power steering system, or if the steering system 4 is configured with SBW, the reaction force device 16 may be configured to apply a reaction force in the direction of rotation opposite to the direction of rotation of the steering shaft.

[0016] The control unit 12 is composed of a hardware processor such as one or more CPUs (Central Processing Units). The storage unit 18 is composed of a non-volatile storage medium such as a hard disk drive (HDD) or a solid state disk (SSD), or a ROM (Read Only Memory) and a RAM (Random Access Memory). The storage unit 18 is not only provided in the steering control device 10, but may also be provided in a data server (not shown) that is communicably connected via the network W.

[0017] The detection unit 14 is composed of, for example, various sensors. The various sensors are composed of, for example, a camera sensor 14A, a steering angle sensor 14B, a steering torque sensor 14C, a vehicle speed sensor 14D, an attitude sensor 14E, an acceleration sensor 14F, a position sensor 14G, and the like. Various detection data output from the various sensors are stored in the storage unit 18 and updated at any time. The detection unit 14 may be configured to output the detection results by interlocking with the control unit 12 in addition to outputting the detection data of the various sensors.

[0018] The camera sensor 14A images, for example, the external environment of the vehicle 1. The camera sensor 14A images a plurality of still images per unit time based on a predetermined frame rate and generates imaging data. The frame rate is, for example, several tens of fps. The camera sensor 14A images, for example, the area in front of the vehicle 1 and acquires imaging data in which the lane is imaged. The imaging data is stored in the storage unit 18 at any time. The imaging data stored in the storage unit 18 is held for a predetermined period and then rewritten in order from the oldest to the new data.

[0019] The steering angle sensor 14B detects the rotation angle of the steering wheel 2. The steering angle sensor 14B detects a first rotation angle in the rightward direction from the neutral position of the steering wheel 2, and a second rotation angle in the leftward direction from the neutral position. The steering angle sensor 14B is composed of, for example, an encoder provided on the steering shaft. The steering angle sensor 14B detects the rotation angle data of the steering wheel 2 based on a predetermined sampling rate.

[0020] The steering torque sensor 14C detects the torque applied around the rotation axis of the steering shaft when the driver operates the steering wheel 2. The steering torque sensor 14C detects a first input torque applied in the rightward rotation direction from the neutral position of the steering wheel 2, and a second input torque applied in the leftward rotation direction from the neutral position. The detected value of the steering torque sensor 14C may also be the detected value of the load of the motor constituting the reaction force device 16 provided in the steering device 4.

[0021] The vehicle speed sensor 14D detects the speed of vehicle 1. The vehicle speed sensor 14D detects, for example, the rotational speed of the wheels 6 and the relative speed of the ground to vehicle 1. The speed of vehicle 1 may be calculated based on the acceleration sensor 14F and the position sensor 14G. In this case, the vehicle speed sensor 14D may be omitted. The attitude sensor 14E detects the attitude of vehicle 1. The attitude sensor 14E is composed of, for example, an angular velocity sensor around 6 axes.

[0022] The acceleration sensor 14F detects the acceleration applied to the vehicle 1. The acceleration sensor 14F is composed of, for example, three-axis angular velocity sensors. The position sensor 14G detects the absolute position of the vehicle 1. The position sensor 14G is composed of, for example, a GPS (Global Positioning System) sensor.

[0023] As shown in Figure 2, vehicle 1 is traveling on lane R. Lane R is indicated by a pair of first and second boundaries W1 and W2. The second boundary W2 is indicated parallel to the first boundary W1. The first and second boundaries W1 and W2 are white or yellow continuous or dashed lane markers. The first boundary W1 is, for example, the boundary line to the left (+Y direction in the figure) of the direction of travel of vehicle 1 (+X direction in the figure). The second boundary W2 is, for example, the boundary line to the right (-Y direction in the figure) of the direction of travel of vehicle 1.

[0024] The control unit 12 determines the state of vehicle 1 (the vehicle itself) traveling in lane R based on the detection results detected by the detection unit 14, and executes necessary control for vehicle 1 based on the determination result. The control unit 12 recognizes the position of vehicle 1 in lane R based on the detection results of the detection unit 14. For example, based on the recognition result of lane R, the control unit 12 outputs a reaction force from the reaction force device 16 to prevent vehicle 1 from deviating from lane R.

[0025] Based on the detection results of the first boundary W1 and the second boundary W2, the control unit 12 controls the reaction force device 16 to perform a first control that applies a reaction force to the steering wheel 2 in order to prevent the vehicle 1 from deviating from the first boundary W1. Based on the detection results of the first boundary W1 and the second boundary W2, the control unit 12 controls the reaction force device 16 to perform a second control that applies a reaction force to the steering wheel 2 in order to prevent the vehicle 1 from deviating from the second boundary W2.

[0026] When a reaction force is output from the reaction force device 16, the driver can feel the reaction force in a direction opposite to the direction of rotation of the steering wheel 2. By rotating the steering wheel 2 in a direction opposite to the direction of rotation of the steering wheel 2, the driver can keep the vehicle 1 within lane R.

[0027] The control unit 12 analyzes the image data captured by the camera sensor 14A. Based on the image data, the control unit 12 detects the lane R in which the vehicle 1 is traveling. Based on the image data, the control unit 12 recognizes the first boundary W1 and the second boundary W2 that indicate the boundary of lane R. The control unit 12 calculates the first relative position (first detected value) of the first boundary W1 with respect to the vehicle 1's current first position P1. The control unit 12 calculates the second relative position (second detected value) of the second boundary W2 with respect to the vehicle 1's current first position P1.

[0028] The control unit 12 calculates the distance in the width direction of lane R based on the first relative position of the first boundary W1 and the second relative position of the second boundary W2. By halving the distance in the width direction of lane R, the control unit 12 calculates the center distance R1 and the position of the center C in the width direction of lane R.

[0029] The control unit 12 calculates the current first position P1 of vehicle 1 in lane R based on the recognition results of the first boundary W1 and the second boundary W2 and other detection data. The control unit 12 calculates, for example, the future second position P2 of vehicle 1 relative to lane R when vehicle 1 moves a predetermined distance x from the current first position P1. The predetermined distance x is adjusted according to conditions such as the current speed of vehicle 1, current acceleration, width of lane R, and attitude of vehicle 1 relative to lane R.

[0030] The control unit 12 calculates a first distance y1 between the second position P2 and the first boundary W1. The control unit 12 calculates the position of the third position P3, which is reached by moving the first distance y1 from the second position P2 toward the first boundary W1 in the width direction of the lane R (Y-axis direction in the figure). The control unit 12 calculates the third position P3 based on the first position P1, the second position P2, and the first distance y1. The third position P3 is the position where the vehicle 1 deviates from the first boundary W1.

[0031] The control unit 12 calculates a straight line L connecting the first position P1 and the second position P2, and a first straight line L1 connecting the first position P1 and the third position P3. The control unit 12 also calculates a first angle θ1 of the first straight line L1 relative to the straight line L.

[0032] The control unit 12 calculates the second distance y2 between the second position P2 and the second boundary W2. The control unit 12 also calculates the position of the fourth position P4, which is reached by moving the second distance y2 from the second position P2 toward the second boundary W2 in the width direction of the lane R (Y-axis direction in the figure). The fourth position P4 is the position where the vehicle 1 deviates from the second boundary W2.

[0033] The control unit 12 calculates the fourth position P4 based on the first position P1, the second position P2, and the second distance y2. The control unit 12 calculates the second straight line L2 connecting the first position P1 and the fourth position P4. The control unit 12 calculates the second angle θ2 of the second straight line L2 with respect to the straight line L. The above calculation method is just one example, and other calculation methods may be used as long as they can calculate the position of the vehicle 1.

[0034] Figure 3 shows the relationship between the steering wheel 2 and the amount of steering input δ (steering angle). The steering angle sensor 14B detects the first amount of steering input δ1 with respect to the first rotation direction of the steering wheel 2 (for example, left rotation). The control unit 12 calculates the first limit amount of steering input δ1m, which is the threshold at which the vehicle 1 deviates from the first boundary W1 at the first amount of steering input δ1. The first limit amount of steering input δ1m is the amount of steering input δ of the steering wheel 2 corresponding to the first angle θ1 (see Figure 2).

[0035] If the amount of steering wheel 2 is operated δ exceeds the first limit operating amount δ1m, it is expected that the vehicle 1 will deviate from the first boundary W1. The control unit 12 sets a first angular region δA in a predetermined angular region where the steering wheel 2 exceeds the first limit operating amount δ1m in the first rotation direction. When the steering wheel 2 is in the first angular region δA where it exceeds the first limit operating amount δ1m, the control unit 12 determines that the vehicle 1 has deviated from the first boundary W1 and performs a first control to apply a reaction force to the steering wheel 2.

[0036] The steering angle sensor 14B detects a second maneuver amount δ2 with respect to the second rotation direction of the steering wheel 2 (for example, right rotation). The control unit 12 calculates a second limit maneuver amount δ2m, which is the threshold at which the vehicle 1 deviates from the second boundary W2 based on the second maneuver amount δ2. The second limit maneuver amount δ2m is the maneuver amount δ of the steering wheel 2 corresponding to the second angle θ2 (see Figure 2).

[0037] If the second operating amount δ2 of the steering wheel 2 exceeds the second limit operating amount δ2m, it is expected that the vehicle 1 will deviate from the second boundary W2. The control unit 12 sets a second angular region δB in a predetermined angular region where the second limit operating amount δ2m is exceeded in the second rotation direction of the steering wheel 2. When the steering wheel 2 is in the second angular region δB where the second limit operating amount δ2m is exceeded, the control unit 12 determines that the vehicle 1 has deviated from the second boundary W2 and performs a second control to apply a reaction force to the steering wheel 2.

[0038] The control unit 12 sets the reaction force device 16 not to output a reaction force when the first operating amount δ1 of the steering wheel 2 is less than or equal to the first limit operating amount δ1m. The control unit 12 sets the reaction force device 16 not to output a reaction force when the second operating amount δ2 of the steering wheel 2 is less than or equal to the second limit operating amount δ2m. For example, the control unit 12 performs a first control in which it increases the first reaction force F1 as the first operating amount δ1 of the steering wheel 2 increases in the first rotation direction from the first limit operating amount δ1m. For example, the control unit 12 performs a second control in which it increases the second reaction force F2 as the second operating amount δ2 of the steering wheel 2 increases in the second rotation direction from the second limit operating amount δ2m.

[0039] The control unit 12 monitors the amount of steering wheel 2's operation δ and determines whether it is close to either the first limit operation amount δ1m or the second limit operation amount δ2m. The control unit 12 compares the first difference between the amount of steering wheel 2's operation δ and the first limit operation amount δ1m with the second difference between the amount of steering wheel 2's operation δ and the second limit operation amount δ2m, and sets the boundary of lane R corresponding to the smaller absolute value as the monitoring target. For example, if the absolute value of the first difference is smaller than the absolute value of the second difference, the control unit 12 sets the monitoring target of the lane R boundary to the first boundary W1. If the first distance y1 decreases while the first boundary W1 is being monitored, and the steering wheel 2 is in the first angular region δA, the control unit 12 performs a first control to apply a first reaction force F1 to the steering wheel 2. For example, if the absolute value of the second difference is smaller than the absolute value of the first difference, the control unit 12 sets the monitoring target of the lane R boundary to the second boundary W2.

[0040] The control unit 12 performs a second control, which applies a second reaction force F2 to the steering wheel 2, when the first distance y1 increases while monitoring the second boundary W2, and the steering wheel 2 is in the second angular region δB. The processing in the first and second controls described above is just an example, and other control methods may be applied as long as a reaction force can be applied to the steering wheel 2.

[0041] Figure 4(A) shows the trajectory of vehicle 1 as it deviates from the first boundary W1. When vehicle 1 deviates from the first boundary W1, the control unit 12 applies a first reaction force F1 to the steering wheel 2 to return vehicle 1 from the first boundary W1 to lane R. Figure 4(B) shows the change over time of the boundary of lane R, which is being monitored. The control unit 12 monitors the first boundary W1. Figure 4(C) shows the change over time of the amount of steering wheel 2 operated δ. Figure 4(D) shows the change over time of the reaction force F applied to the steering wheel 2. As shown, when the first amount of steering wheel 2 operated δ1 exceeds the first limit operating amount δ1m, the first reaction force F1 applied to the steering wheel 2 is stopped.

[0042] When the control unit 12 determines that the vehicle 1 will deviate from the first boundary W1 in the future, it calculates a first limit operating amount δ1m that will cause the vehicle to deviate from the first boundary W1 at a first operating amount δ1, based on the first detected value of the first boundary W1 detected by the detection unit 14 and the first operating amount δ1 in the first rotation direction of the steering wheel 2 for driving the vehicle in the direction of the first boundary W1. The control unit 12 performs first control when the operating amount of the steering wheel 2 exceeds the first limit operating amount. The driver can return the vehicle 1 to lane R by operating the steering wheel 2 in the rotation direction that reduces the first reaction force F1 of the steering wheel 2.

[0043] Figure 5(A) shows the trajectory of vehicle 1 as it deviates from the second boundary W2. When vehicle 1 deviates from the second boundary W2, the control unit 12 applies a second reaction force F2 to the steering wheel 2 to return vehicle 1 from the second boundary W2 to lane R. Figure 5(B) shows the change over time of the boundary of lane R that is being monitored. The control unit 12 monitors the second boundary W2. Figure 5(C) shows the change over time of the amount of steering wheel 2's operation δ. Figure 5(D) shows the change over time of the reaction force F applied to the steering wheel 2. As shown, when the second amount of steering wheel 2's operation δ2 exceeds the second limit operation amount δ2m, a second reaction force F2 is applied to the steering wheel 2. When the second amount of steering wheel 2's operation δ2 becomes less than or equal to the second limit operation amount δ2m, the second reaction force F2 applied to the steering wheel 2 is stopped.

[0044] When the control unit 12 determines that the vehicle 1 will deviate from the second boundary W2 in the future, it calculates a second limit operating amount that will cause the vehicle to deviate from the second boundary based on the second detected value of the second boundary W2 detected by the detection unit 14 and the second operating amount in the second rotation direction opposite to the first rotation direction for driving the vehicle 1 in the direction of the second boundary W2. The control unit 12 performs a second control when the operating amount of the steering wheel 2 exceeds the second limit operating amount. The driver can return the vehicle 1 to lane R by operating the steering wheel 2 in the rotation direction that reduces the second reaction force F2 of the steering wheel 2.

[0045] As shown in Figure 6, the process when the control unit 12 switches the monitoring target of the lane R boundary from the first boundary W1 to the second boundary W2 will be explained. Figure 6(A) shows the driving trajectory when vehicle 1 drives closer to the first boundary W1 side and then closer to the second boundary W2 side in lane R. Figure 6(B) shows the change over time of the lane R boundary that is being monitored. As shown in the figure, the monitoring target of the lane R boundary is the first boundary W1, and then switches to the second boundary W2 at some point. Since the control unit 12 outputs the calculation result based on the frame rate of the camera sensor 14A, the monitoring target of the lane R boundary is immediately switched from the first boundary W1 to the second boundary W2.

[0046] Figure 6(C) shows the change over time of the steering wheel 2's operating amount δ. Since the steering angle sensor 14B detects the rotation angle data of the steering wheel 2 based on a predetermined sampling rate, the detection result of the steering wheel 2's operating amount δ is discretized at a predetermined sampling time. Therefore, the control unit 12 calculates the first limit operating amount δ1m and the second limit operating amount δ2m, which are threshold values ​​for the steering wheel 2, and these values ​​change discretely. At the first timing when the monitoring target of the lane R boundary switches from the first boundary W1 to the second boundary W2, the control unit 12 sets a rate guard G to keep the threshold value of the steering wheel 2's operating amount continuous from the first limit operating amount δ1m to the second limit operating amount δ2m.

[0047] As shown in the figure, when a rate guard G is set as the result of calculating the limit operation amount which is the threshold for the steering wheel 2, there is a small time interval Δt in the rate guard section t1 where the rate guard G is installed, during which the control unit 12 determines that the vehicle 1 has deviated from the second boundary W2. During this small time interval Δt, the control unit 12 switches the target of monitoring the lane boundary R to the second boundary W2. During this small time interval Δt, the control unit 12 reduces the limit operation amount of the steering wheel 2 from the first limit operation amount δ1m to 0 based on the rate guard G. As a result, the control unit 12 determines that during this small time interval Δt, the operation amount δ of the steering wheel 2 exceeds the limit operation amount relative to the second boundary W2.

[0048] Figure 6(D) shows the change in reaction force F applied to the steering wheel 2 over time. As shown in the figure, when the normal control described above is performed during the small time interval Δt of the first timing, the control unit 12 determines that the vehicle 1 has deviated from the second boundary W2, and therefore applies a third reaction force F3 to the steering wheel 2 based on the second control. At this time, the driver may feel discomfort from the third reaction force F3 applied to the steering wheel 2. Figure 6(E) shows the control method for the reaction force F at the first timing. At the first timing, when the target of lane departure monitoring is switched from the first boundary W1 to the second boundary W2, the control unit 12 limits the reaction force F output from the reaction force device 16 for a predetermined period of time.

[0049] Predetermined time:t hold [s] is calculated, for example, based on the following formula (1). t hold =|δ' max -δ' premax | / r (1) However, δ' max [deg]: Current limit manipulation amount before rate guarding, δ' premax [deg]: Previous limit manipulation amount before rate guard execution, r[deg / s]: Rate guard value. The predetermined time only needs to be set at the first timing interval, at least a small time interval Δt or more from the start of rate guard interval t1. The predetermined time may be a constant value.

[0050] The control unit 12 restricts the second control if it determines that the vehicle 1 has deviated from the second boundary W2 during the first time interval in which the threshold value of the steering wheel 2's operation amount is switched from the first limit operation amount δ1m to the second limit operation amount δ2m at the first timing. For example, at the first timing, the control unit 12 restricts the second control so as not to output the third reaction force F3 output from the reaction force device 16 for at least a small time Δt. As a result, the driver can operate the steering wheel 2 without any discomfort at the first timing.

[0051] Similarly, at the second timing when the monitoring target for lane R boundary switches from the second boundary W2 to the first boundary W1, the control unit 12 sets a rate guard G to keep the threshold of the steering wheel 2 operation amount continuous from the second limit operation amount δ2m to the first limit operation amount δ1m. At the second timing when the monitoring target for lane R departure switches from the second boundary W2 to the first boundary W1, the control unit 12 limits the reaction force F output from the reaction force device 16 for a predetermined period of time.

[0052] The control unit 12 restricts the first control if it determines that the steering wheel 2 has deviated from the first boundary W1 during the second time interval in which the threshold value of the steering wheel 2's operation amount is switched from the second limit operation amount δ2m to the first limit operation amount δ1m at the second timing. For example, at the second timing, the control unit 12 restricts the first control so that the fourth reaction force output from the reaction force device 16 is not output for at least a small time Δt. As a result, the driver can operate the steering wheel 2 without any discomfort at the second timing.

[0053] Figure 7 shows the processing flow of the steering control method executed in the steering control device 10. The control unit 12 detects the boundary of the lane R on which the vehicle 1 is traveling based on the detection data from the detection unit 14 (step S100). The control unit 12 calculates the reaction force F applied to the steering wheel 2 based on the relative position of the vehicle 1 in lane R and the detection results of the first boundary W1 and the second boundary W2 (step S102). The control unit 12 determines whether it is the first or second timing for switching the monitoring target of the lane R boundary based on the relative position of the vehicle 1 in lane R and the detection results of the first boundary W1 and the second boundary W2 (step S104).

[0054] If step 104 results in a negative determination, the control unit 12 compares the amount of steering wheel 2's operation with a threshold limit operation amount to determine whether the vehicle 1 has deviated from lane R (step S106). If step 106 results in a negative determination, the control unit 12 stops processing and resumes processing from step 100. If step 106 results in a positive determination, the control unit 12 controls the reaction force device 16 to apply a reaction force in the direction of rotation of the steering wheel 2 (step S108).

[0055] When the control unit determines that vehicle 1 will deviate from the first boundary W1 in the future, it calculates a first limit operating amount δ1m, which is the threshold at which vehicle 1 will deviate from the first boundary W1, based on a first detected value of the first boundary W1 calculated based on the detection result and a first operating amount δ1 in the first rotation direction of the steering wheel to drive vehicle 1 in the direction of the first boundary W1. When the operating amount of the steering wheel 2 exceeds the first limit operating amount δ1m, it performs the first control.

[0056] If the control unit determines that vehicle 1 will deviate from the second boundary W2 in the future, it calculates a second limit operating amount δ2m, which is the threshold at which vehicle 1 will deviate from the second boundary W2, based on the second detected value of the second boundary W2 calculated based on the detection result and the second operating amount δ2 of the steering wheel in the second rotation direction for driving vehicle 1 in the direction of the second boundary W2. When the operating amount of the steering wheel 2 exceeds the second limit operating amount δ2m, it performs the second control. The control unit 12 determines whether or not vehicle 1 has finished deviating from lane R (step 110).

[0057] If step 110 results in a negative determination, the control unit 12 executes the process of step 110 again. If step 110 results in a positive determination, the control unit 12 controls the reaction force device 16 to stop the reaction force output to the steering wheel 2 (step 112). After step 112, the process restarts from step 100. If step 104 results in a positive determination, the control unit 12 limits the reaction force output from the reaction force device 16 for a predetermined period of time (step 114). After step 114, the process restarts from step 100.

[0058] As described above, the steering control device 10 can prevent the driver from feeling any discomfort by limiting the reaction force F supplied from the reaction force device 16 to the steering wheel 2 at the first or second timing when the target of monitoring the boundary of the lane R switches.

[0059] In the embodiments described above, the computer programs executed in each configuration of the steering control device 10 may be provided in the form of being recorded on a computer-readable portable recording medium such as a semiconductor memory, a magnetic recording medium, or an optical recording medium.

[0060] In the above-described embodiment of the steering control device 10, each process performed by the control unit 12 may be applied not only to prevent the vehicle from deviating from the first boundary W1 or the second boundary W2 in lane R, but also when the vehicle 1 changes lanes between two adjacent lanes. The first boundary W1 and the second boundary W2 recognized in lane R may be not only lane marks actually displayed on the road surface, but also virtual lane marks set by the steering control device 10. Furthermore, the first boundary W1 or the second boundary W2 may be the side of a structure or obstacle. [Explanation of symbols]

[0061] 1 vehicle 2 Steering Wheel 4. Steering gear 6 wheels 10 Steering control device 12 Control Unit 14 Detection unit 14A Camera Sensor 14B Steering Angle Sensor 14C Steering Torque Sensor 14D Vehicle Speed ​​Sensor 14E Attitude Sensor 14F Accelerometer 14G position sensor 16 Reaction device 18 Memory section

Claims

1. A detection unit for detecting the lane in which the vehicle is traveling, A reaction force device that applies a reaction force to the steering direction of the steering wheel for operating the steering device of the vehicle, The system includes a control unit that recognizes the position of the vehicle in the lane based on the lane detection result and outputs a reaction force from the reaction force device to prevent the vehicle from deviating from the lane, The control unit, based on the detection results of the pair of first and second boundaries of the lane, performs a first control to prevent the vehicle from deviating from the first boundary by controlling the reaction force device to apply the reaction force to the steering wheel, or performs a second control to prevent the vehicle from deviating from the second boundary by controlling the reaction force device to apply the reaction force to the steering wheel. At the first timing when the target of lane departure monitoring is switched from the first boundary to the second boundary, or at the second timing when the target of lane departure monitoring is switched from the second boundary to the first boundary, the reaction force output from the reaction force device is limited for a predetermined period of time. The control unit, The straight line is calculated connecting the first position, which is the current position of the vehicle in the lane, and the second position, which is the future position of the vehicle in the lane after it has moved a predetermined distance from the first position. A first straight line is calculated connecting the first position and the third position, which is the position where the vehicle deviates from the first boundary. The first angle, which is the angle of the first straight line with respect to the aforementioned straight line, is calculated. A first limit operating amount, which is the amount of steering wheel operation corresponding to the first angle, is calculated. A second straight line is calculated connecting the first position and the fourth position, which is the position where the vehicle deviates from the second boundary. The second angle, which is the angle of the second line with respect to the aforementioned line, is calculated. The second limit operating amount, which is the amount of steering wheel operation corresponding to the second angle, is calculated. The amount of steering wheel operation is monitored, Determine whether it is close to either the first limit control amount or the second limit control amount. The first difference between the steering wheel operation amount and the first limit operation amount is compared with the second difference between the steering wheel operation amount and the second limit operation amount. The lane boundary corresponding to the smaller absolute value is set as the target for monitoring lane departure. At the first timing for switching the target of lane departure monitoring from the first boundary to the second boundary, a rate guard is set to keep the threshold of the steering wheel operation amount continuous from the first limit operation amount to the second limit operation amount. In a rate guard section provided to connect the first limit operating amount to the second limit operating amount, during the predetermined time, which is a small time interval during which it is determined that the vehicle has deviated from the second boundary, the reaction force is limited without applying the reaction force based on the second control. At the second timing in which the target of lane departure monitoring is switched from the second boundary to the first boundary, a rate guard is set to keep the threshold of the steering wheel operation amount continuous from the second limit operation amount to the first limit operation amount. In a section where a rate guard is provided to connect the second limit operating amount to the first limit operating amount, during the predetermined time which is a small period of time in which it is determined that the vehicle has deviated from the first boundary, the reaction force is limited without applying the reaction force based on the first control. Steering control device.

2. A steering control method performed by a computer provided in a steering control device that controls the steering of a vehicle, wherein the computer is: The system detects the lane in which the vehicle is traveling, Based on the detection results of the pair of first and second boundaries of the lane, the position of the vehicle in the lane is recognized. To prevent the vehicle from deviating from the first boundary, a first control is performed by controlling a reaction force device provided on the steering wheel to apply a reaction force to the steering wheel, or to prevent the vehicle from deviating from the second boundary, a second control is performed by controlling the reaction force device to apply the reaction force to the steering wheel. At the first timing when the target of lane departure monitoring is switched from the first boundary to the second boundary, or at the second timing when the target of lane departure monitoring is switched from the second boundary to the first boundary, the reaction force output from the reaction force device is limited for a predetermined period of time. The aforementioned computer, The straight line is calculated connecting the first position, which is the current position of the vehicle in the lane, and the second position, which is the future position of the vehicle in the lane after it has moved a predetermined distance from the first position. A first straight line is calculated connecting the first position and the third position, which is the position where the vehicle deviates from the first boundary. The first angle, which is the angle of the first straight line with respect to the aforementioned straight line, is calculated. A first limit operating amount, which is the amount of steering wheel operation corresponding to the first angle, is calculated. A second straight line is calculated connecting the first position and the fourth position, which is the position where the vehicle deviates from the second boundary. The second angle, which is the angle of the second line with respect to the aforementioned line, is calculated. The second limit operating amount, which is the amount of steering wheel operation corresponding to the second angle, is calculated. The amount of steering wheel operation is monitored, Determine whether it is close to either the first limit control amount or the second limit control amount. The first difference between the steering wheel operation amount and the first limit operation amount is compared with the second difference between the steering wheel operation amount and the second limit operation amount. The lane boundary corresponding to the smaller absolute value is set as the target for monitoring lane departure. At the first timing for switching the target of lane departure monitoring from the first boundary to the second boundary, a rate guard is set to keep the threshold of the steering wheel operation amount continuous from the first limit operation amount to the second limit operation amount. In a rate guard section provided to connect the first limit operating amount to the second limit operating amount, during the predetermined time, which is a small time interval during which it is determined that the vehicle has deviated from the second boundary, the reaction force is limited without applying the reaction force based on the second control. At the second timing in which the target of lane departure monitoring is switched from the second boundary to the first boundary, a rate guard is set to keep the threshold of the steering wheel operation amount continuous from the second limit operation amount to the first limit operation amount. In a section where a rate guard is provided to connect the second limit operating amount to the first limit operating amount, during the predetermined time which is a small period of time in which it is determined that the vehicle has deviated from the first boundary, the reaction force is limited without applying the reaction force based on the first control. Steering control method.

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