JP4715372B2 - Steering support device - Google Patents

Description

  The present invention relates to a steering assistance device that provides steering assistance by applying a steering torque to a steering mechanism of a vehicle.

2. Description of the Related Art Conventionally, as a steering assistance device that provides steering assistance by applying a steering torque to a vehicle steering mechanism, as described in Japanese Patent Laid-Open No. 2001-10518, the front of the vehicle is imaged by a camera, and the captured image information Based on the travel path and the position of the vehicle relative to the travel path, calculating the basic steering assist torque based on the shape of the travel path, calculating the corrected steering assist torque based on the position of the vehicle, An output steering assist torque is calculated based on the corrected steering assist torque, and an operation amount of the steering actuator is determined based on the output steering assist torque. This device intends to improve control accuracy by performing steering control using a shape parameter and a vehicle position parameter with high detection accuracy without using a yaw rate.
JP 2001-10518 A

  However, in such a steering assist device, when the steering assist torque is applied, the driver of the vehicle may steer in a direction opposite to the steering assist torque. In this case, if the steering assist device continues to apply assist torque against the steering of the driver, it takes time for the vehicle to travel in the direction intended by the driver, and the driver feels uncomfortable with the steering of the steering wheel. There are problems such as feeling.

  SUMMARY OF THE INVENTION An object of the present invention is to provide a steering assist device capable of performing steering assist control adapted to steering of a driver's steering wheel.

That is, the steering assist device according to the present invention is a steering assist device that applies a steering torque to a steering mechanism so that the vehicle travels along a travel path based on an image obtained by imaging a travel path ahead of the vehicle. Vehicle position detecting means for detecting an offset from the center of the lane of the vehicle with respect to the width direction of the road, integrating means for integrating the offset from the center of the lane of the vehicle, and the steering mechanism based on an integral value of the integrating means A steering torque setting means for setting a steering torque to be applied, and an integration stopping means for preventing the integral value of the integrating means from increasing when the steering direction of the steering torque is different from the steering direction in the steering of the driver of the vehicle. with the door, when the integration stopping means, if the driver in a different steering direction steering direction of the steering torque is steering, that the steering And it is configured to reduce the integral value of the integrating means elapsed time or based on the distance traveled from.
In the steering assist device according to the present invention, the steering torque setting means continues to apply the steering torque to the steering mechanism during a period in which the driver is steering the steering wheel in a steering direction different from the steering direction of the steering torque. Is preferred.

  According to the present invention, when the steering direction of the driver of the vehicle is different from the steering direction in the steering assist control, the steering torque can be suppressed to be small by preventing an increase in the steering torque of the steering assist control. For this reason, when the driver loosens the steering of the steering wheel, the vehicle can be prevented from traveling in the left-right direction. As a result, it is possible to perform steering assist control adapted to the steering of the driver.

  According to the present invention, when the steering direction of the driver of the vehicle and the steering direction in the steering assist control are different, the steering assist control adapted to the steering of the driver is prevented by preventing an increase in the steering torque of the steering assist control. It can be carried out.

Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings. In the description of the drawings, the same elements are denoted by the same reference numerals, and redundant description is omitted.
(First embodiment)
FIG. 1 is a schematic configuration diagram of a steering assist device according to a first embodiment of the present invention.

  As shown in FIG. 1, a steering assist device 1 according to the present embodiment is a device that provides steering torque to a steering force transmission system of a vehicle to assist the driver of the vehicle. Used for lane keeping control that maintains the position of the vehicle at the center position. The vehicle steering force transmission system includes a steering shaft 3, a gear portion 4, and a tie rod 6 as main components. The steering shaft 3 is connected to the handle 2 and transmits the steering force of the handle 2 to the gear portion 4 and the tie rod 6.

  The gear unit 4 converts the steering torque transmitted from the steering shaft 3 into a horizontal force. As the gear part 4, a rack and pinion type, for example, is used. The gear unit 4 receives the assist force of the assist motor 5 and moves the tie rod 6 to steer the steered wheels 7.

  The gear unit 4 is provided with a torque sensor 8. The torque sensor 8 functions as a steering torque detection means for detecting the steering torque of the handle 2. As this torque sensor 8, for example, a torsion bar (not shown) is arranged between the steering shaft 3 and a pinion shaft (not shown), and the torsion bar is twisted according to the steering torque by two rotation sensors (not shown). What is detected by is used.

  The motor 5 is a motor that assists the steering force of the handle 2 and applies an assist force according to, for example, a steering torque to the steering force transmission system. In FIG. 1, the motor 5 is of a rack assist type that gives an assist force to the rack, but may be of a column assist type or the like.

  The steering assist device 1 is provided with an ECU (Electronic Control Unit) 20. The ECU 20 performs control processing for the entire apparatus, and includes, for example, a CPU, a ROM, a RAM, an input signal circuit, an output signal circuit, a power supply circuit, and the like. The steering assist device 1 is provided with a camera 11. The camera 11 functions as an imaging unit that images the front of the vehicle. For example, a CCD camera or the like is used. Image information captured by the camera 11 is input to the ECU 20.

  The ECU 20 functions as a vehicle position detection unit that detects the position of the vehicle with respect to the width direction of the travel path based on the image information. For example, the ECU 20 performs image processing on the captured image, recognizes a white line included in the image information, and detects the position of the vehicle with respect to the width direction of the traveling road based on the recognized shape and position of the white line. At that time, the positional deviation of the vehicle from the center position of the lane is referred to as an offset.

  Further, the ECU 20 functions as a steering assist control unit that performs steering assist control so that the steering torque does not increase when the steering direction of the steering torque is different from the steering direction in the steering of the driver of the vehicle.

  The steering assist device 1 is provided with a vehicle speed sensor 12. The vehicle speed sensor 12 functions as a vehicle speed detection unit that detects the traveling speed of the vehicle.

  FIG. 2 is a schematic diagram of a basic control block of the steering assist control in the steering assist device 1 according to the present embodiment.

  As shown in FIG. 2, in the steering assist device 1, image information of the traveling road ahead of the vehicle imaged by the camera 11 is input to the ECU 20, and the curvature (R) of the traveling road, the vehicle position ( D) and the vehicle orientation (θ) relative to the white line are detected. The curvature of the traveling road is calculated based on, for example, the detection state of the white line on the traveling road. The vehicle position is a position with respect to the width direction of the travel path of the vehicle. This vehicle position is calculated based on, for example, a white line detection state. The direction of the vehicle with respect to the white line is calculated based on the detection state of the left and right white lines, for example.

  The curvature of the travel path, the vehicle position, and the vehicle direction are each multiplied by a predetermined gain (G) and then used for calculating the target lateral acceleration. The target lateral acceleration is a lateral acceleration necessary for returning the vehicle to the center of the lane. Then, by multiplying the target lateral acceleration by a predetermined coefficient, a steering torque (assist steering force) necessary for maintaining the lane is calculated. This steering torque is applied to the steering mechanism.

  On the other hand, an actuator (motor 5) of an electric power steering (EPS) applies an assist force in accordance with the steering force of the driver of the vehicle. A steering wheel steering force and an assisting force are applied to the steering mechanism from the actuator of the electric power steering.

  The steering mechanism is provided with steering force, steering assist force, and assist steering force for maintaining the lane as steering force. In response to the steering force, the traveling direction of the vehicle changes.

  FIG. 3 is a flowchart showing a steering direction detection process in the steering assist device 1 according to the present embodiment. This steering direction process is a process for detecting whether or not the steering direction of the steering torque applied by the steering assist device 1 is different from the steering direction in the steering of the driver of the vehicle. A series of control processes in FIG. 3 are repeatedly executed by the ECU 20 at a predetermined cycle, for example.

  First, as shown in S10 of FIG. 3, it is determined whether or not the steering wheel previous value flag in the reverse direction is set to OFF. The reverse steering steering previous value flag is the previous value of the reverse steering steering flag. The steering wheel steering flag in the reverse direction is set to ON when the steering wheel of the driver is in the reverse direction with respect to the steering direction of the steering torque applied by the steering assistance device 1 to the steering mechanism. This flag is set to OFF when the steering wheel of the driver is not in the reverse direction with respect to the steering direction of the applied steering torque.

  If it is determined in S10 that the steering wheel previous value flag in the reverse direction is not set to OFF, the absolute value of the target lateral acceleration (target G) is smaller than the second lateral acceleration value Gb, and the driver It is determined whether or not the absolute value of the steering torque is smaller than the second steering torque value Tb (S12). The target lateral acceleration is calculated based on a vehicle offset or the like. The target lateral acceleration is set such that the side on which the vehicle turns right is positive and the side on which the vehicle turns left is negative. A steering wheel steering torque based on the detection value of the torque sensor 8 is used. This steering torque is positive in the right turn direction and negative in the left turn direction. The second lateral acceleration value Gb and the second steering torque value Tb are set values set in the ECU 20 in advance.

  If it is determined in S12 that the absolute value of the target lateral acceleration is smaller than the second lateral acceleration value Gb and the absolute value of the steering wheel torque of the driver is smaller than the second steering torque value Tb, the steering wheel steering off timer Is incremented (S14). On the other hand, when the absolute value of the target lateral acceleration is not smaller than the second lateral acceleration value Gb or the absolute value of the steering wheel torque of the driver is not smaller than the second steering torque value Tb in S12, the steering wheel steering off timer is set. It is reset (S16).

  Then, the process proceeds to S18, where it is determined whether or not the steering wheel steering off timer has exceeded the second time B. The second time B is a set time value preset in the ECU 20. If it is determined in S18 that the steering wheel steering off timer has exceeded the second time B, the steering wheel steering flag in the reverse direction is set to off (S20). On the other hand, if it is determined in S18 that the steering wheel steering off timer does not exceed the second time B, the steering wheel steering flag in the reverse direction is set to ON (S32).

  By the way, if it is determined in S10 that the steering wheel previous value flag in the reverse direction is set to OFF, the target lateral acceleration (target G) is larger than the first lateral acceleration value Ga and the driver's It is determined whether or not the steering wheel steering torque is smaller than a negative value -Ta in the first steering torque value Ta (S22). The target lateral acceleration is calculated based on a vehicle offset or the like. A steering wheel steering torque based on the detection value of the torque sensor 8 is used. The first lateral acceleration value Ga and the first steering torque value Ta are set values set in the ECU 20 in advance.

  When it is determined in S22 that the target lateral acceleration is larger than the first lateral acceleration value Ga and the driver's steering wheel torque is smaller than the negative value -Ta in the first steering torque value Ta, the steering wheel steering on timer Is incremented (S24). Then, the process proceeds to S30. On the other hand, if it is determined in S22 that the target lateral acceleration is not greater than the first lateral acceleration value Ga or the driver's steering torque is not smaller than the negative value -Ta of the first steering torque value Ta, It is determined whether or not the target lateral acceleration is smaller than a negative value −Ga in the first lateral acceleration value Ga and the driver's steering wheel steering torque is larger than the first steering torque value Ta (S26).

  If it is determined in S26 that the target lateral acceleration is smaller than the negative value -Ga in the first lateral acceleration value Ga and the driver's steering torque is greater than the first steering torque value Ta, the process proceeds to S24. Transition. On the other hand, if it is determined in S26 that the target lateral acceleration is not smaller than the negative value -Ga in the first lateral acceleration value Ga or the driver's steering torque is not larger than the first steering torque value Ta, The steering wheel steering on timer is reset (S28).

  Then, the process proceeds to S30, where it is determined whether or not the steering wheel steering on timer has exceeded the first time A. When the steering wheel steering on timer does not exceed the first time A, the process proceeds to S20. On the other hand, when the steering wheel on timer exceeds the first time A, the steering wheel steering flag in the reverse direction is set to on (S32).

  Then, the flow shifts to S34, where the value of the reverse direction steering flag is set as the previous value of the reverse direction steering flag. Then, the control process ends.

  According to such a steering direction detection process, the absolute value of the target lateral acceleration exceeds the first acceleration value Ga, and the steering wheel steering torque in the direction opposite to the target lateral acceleration is greater than the first steering torque value Ta. In this case, the steering wheel flag in the reverse direction is turned on, and it can be detected that the steering wheel of the driver in the reverse direction is being performed with respect to the steering torque applied from the steering assist device 1.

  4 and 5 are flowcharts of steering assist control processing in the steering assist device according to the present embodiment. A series of control processes of the steering assist control process is repeatedly executed by the ECU 20 at a predetermined cycle, for example.

  First, as shown in S40 of FIG. 4, the target lateral acceleration (target G) is calculated. The target lateral acceleration is a lateral acceleration necessary for moving the vehicle to the center of the lane, and is calculated based on a vehicle offset (a vehicle position shift amount with respect to the center position of the lane) or the like. Then, the process proceeds to S42, and filter processing is performed. The filter process is a process performed to remove noise from the target lateral acceleration value.

  Then, the process proceeds to S44, where it is determined whether or not the target lateral acceleration is smaller than a value obtained by subtracting the lateral acceleration value ΔG from the target lateral acceleration threshold value. The target lateral acceleration threshold value is a variable set in the ECU 20. The lateral acceleration value ΔG is a set value set in the ECU 20 in advance. If it is determined that the target lateral acceleration is smaller than the value obtained by subtracting the lateral acceleration value ΔG from the target lateral acceleration threshold value, the left direction is set in the temporary steering direction flag. On the other hand, if the target lateral acceleration is not smaller than the value obtained by subtracting the lateral acceleration value ΔG from the target lateral acceleration threshold value, is the target lateral acceleration greater than the value obtained by adding the lateral acceleration value ΔG to the target lateral acceleration threshold value? It is determined whether or not (S48).

  If it is determined in S48 that the target lateral acceleration is not larger than the value obtained by adding the lateral acceleration value ΔG to the target lateral acceleration threshold value, the process proceeds to S54. On the other hand, if it is determined that the target lateral acceleration is greater than the value obtained by adding the lateral acceleration value ΔG to the target lateral acceleration threshold value, the right direction is set to the temporary steering direction flag (S50).

  Then, the process proceeds to S52, where the target lateral acceleration is set as the target lateral acceleration threshold value. Then, the process proceeds to S54. In S54, it is determined whether or not the previous value of the steering direction flag is an intermediate value. If the previous value of the steering direction flag is an intermediate value, the steering direction timer is incremented (S56). On the other hand, if the previous value of the steering direction flag is not an intermediate value, the steering direction timer is reset (S58).

  Then, the process proceeds to S60 in FIG. 5, and it is determined whether or not the temporary steering direction flag is the same as the previous value of the temporary steering direction flag. If the temporary steering direction flag is not the same as the previous value of the temporary steering direction flag, the steering direction change flag is set to ON (S62). On the other hand, when the temporary steering direction flag is the same as the previous value of the temporary steering direction flag, the steering direction change flag is set to OFF (S64).

  Then, the flow shifts to S66, where it is determined whether or not the steering direction change flag is on, or the reverse steering wheel steering flag is on. If the steering direction change flag is on or the reverse steering wheel steering flag is on, an intermediate value is set as the steering direction flag (S68). On the other hand, if the steering direction change flag is not on and the reverse steering wheel steering flag is not on, whether the previous value of the steering direction flag is not an intermediate value or whether the steering direction timer has exceeded a predetermined time ΔT or not. Determination is made (S70). The predetermined time ΔT is a set time set in advance in the ECU 20.

  If the previous value of the steering direction flag is not an intermediate value or the steering direction timer is equal to or longer than the predetermined time ΔT in S70, the value of the temporary steering direction flag is set as the steering direction flag (S72). On the other hand, if the previous value of the steering direction flag is an intermediate value and the steering direction timer is not longer than the predetermined time ΔT, the previous value of the steering direction flag is set as the steering direction flag (S74).

  Then, the process proceeds to S76, and a steering torque calculation process is performed. The steering torque calculation process is a process for calculating a steering torque necessary for steering assistance. For example, as shown in FIG. 6, the steering torque (EPS required torque) is calculated based on the target lateral acceleration.

  In FIG. 6, the steering torque corresponding to the target lateral acceleration (target G) is set, but the steering torque is set to a different value when the steering wheel is increased and when the steering wheel is turned back. The absolute value of the steering torque is set to be larger when the cut is increased than when the cut is returned. In the target lateral acceleration-steering torque characteristic of FIG. 6, an intermediate line (dashed line) is set between the additional line (thick solid line) and the return line (thin solid line).

  If the steering wheel steering flag in the reverse direction is turned on in S66 of FIG. 5, that is, if the driver is steering the steering wheel in the direction opposite to the steering assist steering torque, the steering direction flag is set to the intermediate value. It is set (S68 in FIG. 5), and in FIG. 6, an intermediate line is used for calculating the steering torque. That is, when the steering wheel is increased, the calculated steering torque becomes a value of an intermediate line smaller than the increased line, and the steering torque is set small. As a result, when the driver is steering the steering wheel in a direction opposite to the steering torque for steering assistance, the steering torque for steering assistance is set smaller than when the driver is not.

  Then, the process proceeds to S78 in FIG. 5, and the driving process of the motor 5 is performed. The driving process of the motor 5 is a process of driving and controlling the motor 5 so that the steering torque set in S76 is applied to the steering mechanism. By driving the motor 5, a steering torque for steering assistance is applied to the steering mechanism of the vehicle.

  As described above, according to the steering assistance device 1 according to the present embodiment, when the steering direction of the driver of the vehicle and the steering direction in the steering assistance control are different, the steering torque of the steering assistance control is compared with the case where it is not. A small value is set to prevent an increase in steering torque in the steering assist control.

  That is, as shown in FIG. 7, when the vehicle offset increases, the steering torque output (torque output) increases as steering assist control in order to return the vehicle position to the center of the lane. At this time, if there is steering in the opposite direction to the steering assist control, the steering torque of the steering assist control decreases (solid line in FIG. 7). In the prior art, the steering torque increases according to the vehicle offset (broken line in FIG. 7).

In this way, when the steering direction of the driver of the vehicle is different from the steering direction in the steering assist control, the steering torque of the steering assist control is set to be smaller than that when the steering direction is not so as to prevent the steering torque of the steering assist control from increasing As a result, the driver can be prevented from feeling uncomfortable with the steering wheel operation, and a good steering feeling can be maintained. Therefore, it is possible to perform steering assist control adapted to the steering of the driver.
(Second embodiment)
Next, a steering assist device according to a second embodiment of the present invention will be described.

  The steering assist device according to the present embodiment increases the steering torque by preventing the integral value of the vehicle offset from increasing when the steering direction of the steering torque of the steering assist control is different from the steering direction of the steering wheel of the driver. It is to prevent. The steering assist device according to the present embodiment has the same hardware configuration as the steering assist device according to the first embodiment shown in FIG. Further, the steering assist device according to the present embodiment performs almost the same control processing as the steering assist device according to the first embodiment shown in FIG. 2, and the steering direction of the steering assist device according to the first embodiment shown in FIG. A detection process is executed to detect whether the steering direction of the steering torque applied by the steering assist device 1 is different from the steering direction in the steering of the driver of the vehicle.

  FIG. 8 is a flowchart of the steering assist control process of the steering assist device according to the present embodiment. A series of control processes in the steering assist control process is repeatedly executed by the ECU 20 at a predetermined cycle, for example.

  First, as shown in S80 of FIG. 8, it is determined whether or not steering in the reverse direction is being performed. That is, it is determined whether the steering direction of the driver's steering wheel is different from the steering direction of the steering torque of the steering assist control. If it is determined that steering in the reverse direction is being performed, the integral gain is set to zero (S82). On the other hand, if it is determined that steering in the reverse direction has not been performed, a predetermined gain value Ki is set as the integral gain (S84). The integral gain is used for a vehicle offset integral process.

  Then, the process proceeds to S86, and an offset integral value obtained by adding a value obtained by multiplying the previous value of the offset integral value by the integral gain and the vehicle offset is set. Then, the offset integral value is set as the previous value of the offset integral value (S88).

Then, the process proceeds to S90, and the target lateral acceleration (target G) is calculated. The target lateral acceleration is a lateral acceleration necessary for moving the vehicle to the center of the lane , and is calculated based on an integrated value of an offset from the center of the vehicle. Then, the process proceeds to S92, and a steering torque calculation process is performed. The steering torque calculation process is a process for calculating a steering torque necessary for steering assistance, and a steering torque calculation process is performed based on the target lateral acceleration.

  Then, the process proceeds to S94, and the driving process of the motor 5 is performed. The driving process of the motor 5 is a process of driving and controlling the motor 5 so that the steering torque set in S92 is applied to the steering mechanism. By driving the motor 5, a steering torque for steering assistance is applied to the steering mechanism of the vehicle.

  As described above, according to the steering assist device according to the present embodiment, when the steering direction of the driver of the vehicle is different from the steering direction in the steering assist control, the integral value of the vehicle offset is not increased, and the integration is performed. It is possible to prevent the target lateral acceleration set based on the value from increasing, and consequently to prevent the steering torque from increasing, and to keep the steering torque small.

  That is, as shown in FIG. 9, when the offset of the vehicle increases, if the offset is integrated as it is, the integrated value of the offset increases (broken line in FIG. 9). However, in the steering assist device according to the present embodiment, when there is steering in the direction opposite to the steering assist control, the increase of the integral value is stopped and the integral value of the offset is made constant.

  As a result, as shown in FIG. 10, when the driver loosens the steering wheel, it is possible to prevent the vehicle from moving from side to side. The broken line in FIG. 10 is the travel route of the vehicle 60 in the prior art, and the solid line in FIG. 10 is the travel route of the vehicle 60 in the steering assist control of the steering assist device according to the present embodiment (the present invention). As described above, according to the steering assist device according to the present embodiment, even when the driver steers the steering wheel, the driving stability of the vehicle and the control followability can be ensured, and the steering assist control adapted to the steering wheel of the driver is achieved. It can be performed.

  Further, in the steering assist device according to the present embodiment, the integrated value can be decreased based on the elapsed time or the travel distance from the time point when the steering in the reverse direction is detected. Thus, the steering torque can be suppressed by decreasing the integral value.

  Each embodiment mentioned above shows an example of the steering assistance device concerning the present invention. The steering assist device according to the present invention is not limited to the above, and the steering assist device according to the embodiment is modified or applied to others so as not to change the gist described in each claim. It may be a thing. For example, in this embodiment, the case where the present invention is applied to a device that assists the steering of a driver who performs steering of the vehicle has been described. However, the present invention may be applied to a device that performs automatic steering.

1 is a schematic configuration diagram of a steering assist device according to a first embodiment of the present invention. It is a block schematic diagram of the steering assistance control in the steering assistance apparatus of FIG. It is a flowchart which shows the steering direction detection process in the steering assistance apparatus of FIG. It is a flowchart which shows the steering assistance control process in the steering assistance apparatus of FIG. It is a flowchart which shows the steering assistance control process in the steering assistance apparatus of FIG. It is explanatory drawing of the steering torque reduction in the steering assistance control process of the steering assistance apparatus of FIG. It is explanatory drawing of the steering torque output in the steering assistance control process of the steering assistance apparatus of FIG. It is a flowchart which shows the steering assistance control process in the steering assistance apparatus which concerns on 2nd embodiment of this invention. It is explanatory drawing of the offset integral value in the steering assistance control of the steering assistance apparatus of FIG. It is explanatory drawing of the vehicle travel in the steering assistance control of the steering assistance apparatus of FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Steering assistance apparatus, 2 ... Handle, 11 ... Camera (imaging means), 12 ... Vehicle speed sensor, 20 ... ECU.

Claims (2)

In a steering assist device that applies a steering torque to a steering mechanism so that the vehicle travels along a travel path based on an image of a travel path ahead of the vehicle,
Vehicle position detection means for detecting an offset from the lane center of the vehicle with respect to the width direction of the travel path;
Integrating means for integrating the offset from the lane center of the vehicle;
Steering torque setting means for setting a steering torque to be applied to the steering mechanism based on an integral value of the integrating means;
Integration stopping means for preventing the integral value of the integrating means from increasing when the steering direction of the steering torque is different from the steering direction in steering of the driver of the vehicle;
With
The integral stop means reduces the integral value of the integral means based on an elapsed time or a travel distance from the time of steering when the driver steers the steering wheel in a steering direction different from the steering direction of the steering torque. ,
A steering assist device characterized by the above. The steering torque setting means continues to apply the steering torque to the steering mechanism during a period in which the driver is steering the steering wheel in a steering direction different from the steering direction of the steering torque.
The steering assist device according to claim 1.

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