CN109774711B - Vehicle transverse control system capable of weight-modulating lane model and method thereof - Google Patents
Vehicle transverse control system capable of weight-modulating lane model and method thereof Download PDFInfo
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- CN109774711B CN109774711B CN201711127750.5A CN201711127750A CN109774711B CN 109774711 B CN109774711 B CN 109774711B CN 201711127750 A CN201711127750 A CN 201711127750A CN 109774711 B CN109774711 B CN 109774711B
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Abstract
The invention provides a vehicle transverse control system capable of weighting and modulating a lane model and a method thereof. The vehicle transverse control system capable of weighting and modulating the lane model comprises a camera, an image processing device, a controller and a steering device, wherein the camera shoots towards the front of the vehicle and outputs the front picture data. The image processing device receives and analyzes the picture data in front of the vehicle to obtain lane characteristic points, and then a lane fitting curve is established according to the lane characteristic points and the pre-view weight. The controller comprises vehicle dynamic parameters and a preview distance, and the preview weight is changed according to the change of the preview distance. And the controller calculates and generates steering control force weight according to the lane fitting curve and the vehicle dynamic parameters. The steering device controls steering of the vehicle in accordance with the steering control force weight. Therefore, the magnitude of the control force involved by the steering device is adjusted through the preview weight and the steering control force weight, and the control force can be switched smoothly.
Description
Technical Field
The present invention relates to a vehicle lateral control system and method thereof, and more particularly, to a vehicle lateral control system and method thereof capable of weighting and modulating a lane model.
Background
The lane line tracking control system is a vehicle control system that detects a lane line using image information obtained from a camera sensor and prevents a vehicle from deviating from the lane line according to the lane line detection result, and may also be referred to as a vehicle lateral control system. In general, a lane line following control system controls steering by generating an assist steering torque in a steering control device so that a vehicle is controlled not to deviate from a lane line while the vehicle is traveling. In addition, a lane line tracking control system has been developed which controls the steering of a vehicle to make the vehicle follow the center of a road and thereby perform lane line tracking control.
Many vehicle lateral control systems are proposed at present, but the conventional vehicle lateral control system sets a reference and a tracking position to be tracked by a vehicle according to a driving tendency of a driver, and thus a road or a state of the driver has a great influence thereon. When the vehicle deviates from the reference tracking position, the system may suddenly apply control to track the reference tracking position, which may easily give a sense of discomfort to the driver. Moreover, the conventional vehicle lateral control system calculates the lateral error by using a lane model with equal weight, and the lateral error and inaccuracy are prone to occur in the lane curve fitting process, and the phenomenon can cause the vehicle lateral control system to have a misjudgment condition. In addition, in the known technology, the process of switching the steering control force is easy to generate an emergency control force, an unsafe condition caused by the emergency control force and a problem of influencing the driving control feeling.
Therefore, there is no weight-adjustable lane model lateral control system and method for increasing the smoothness, safety and stability of the steering control force for man-machine switching in the market, so the related manufacturers seek the solution.
Disclosure of Invention
Therefore, an object of the present invention is to provide a lateral vehicle control system and method capable of adjusting a lane model by weight, wherein the lane feature points are adjusted by weight according to a look-ahead distance required by a controller, and then curve-fitting is performed to obtain a more accurate lane model. In addition, the control force magnitude of the intervention of the steering device is adjusted through the steering control force weight with multiple consideration, the control force can be flexibly adjusted and planned according to the requirement, and the control force can be smoothly switched, so that the safety of the switching control force is improved, and the adverse effect and uncomfortable feeling of the sudden control force on driving are greatly reduced. In addition, under the interactive regulation and control of the preview weight and the steering control force weight, the system can smoothly switch the steering control force so as to solve the problems that sudden control force is easy to generate in the process of switching the steering control force in the prior art, unsafe conditions caused by the sudden control force are easy to generate, and the driving control feeling is influenced.
One embodiment according to aspects of the present invention provides a vehicle lateral control system for a weight-modulated lane model for controlling a vehicle. The vehicle transverse control system capable of weighting and modulating the lane model comprises a camera, an image processing device, a controller and a steering device, wherein the camera is arranged on the vehicle, and the camera shoots towards the front of the vehicle and outputs picture data in front of the vehicle. The image processing device is connected with the camera according to the picture data signal in front of the vehicle, receives and analyzes the picture data in front of the vehicle to obtain a plurality of lane characteristic points, and establishes a lane fitting curve according to the lane characteristic points and the preview weight. In addition, the controller is connected with the image processing device according to the lane fitting curve signal and comprises a plurality of vehicle dynamic parameters and a preview distance, and the preview weight is changed according to the change of the preview distance. The controller generates a steering control force weight according to the lane fitting curve and the vehicle dynamic parameter calculation. The steering device is connected with the controller according to the steering control force weight signal and is arranged on the vehicle, and the steering device controls the steering of the vehicle according to the steering control force weight.
Therefore, the vehicle transverse control system of the weight-adjustable lane model adjusts the magnitude of the control force of the intervention of the steering device through the steering control force weight with multiple consideration, can be flexibly adjusted and planned according to the requirement, can smoothly switch the control force, further improves the safety of switching the control force and greatly reduces the adverse effect and uncomfortable feeling of sudden control force on driving.
Other examples of the foregoing embodiments are as follows: the steering control force weight of the controller may be a lateral offset weight value, and the vehicle is separated from the lane-fitting curve by a lateral offset distance, and the lateral offset weight value increases as the lateral offset distance increases. Furthermore, the steering control force weight of the controller can be a predicted weight value of the time exceeding the lane line, and the controller calculates the time exceeding the lane line according to the speed, the acceleration and the yaw rate. When the time of exceeding the lane line is less than or equal to a preset time, the weight value of the time of exceeding the lane line is estimated to be equal to 1. On the contrary, when the time exceeding the lane line is greater than the preset time, the weight value of the estimated time exceeding the lane line is decreased along with the increase of the time exceeding the lane line. In addition, the steering control force weight of the controller can be determined according to a lateral offset weight value and a maximum value of a predicted time weight value exceeding the lane line. The vehicle is spaced from the lane-fitting curve by a lateral offset distance, and the lateral offset weight value increases as the lateral offset distance increases. The steering control force weight of the controller can be a predicted weight value of the time exceeding the lane line, and the controller calculates the time exceeding the lane line according to the speed, the acceleration and the yaw rate. When the time of exceeding the lane line is less than or equal to a preset time, the weight value of the time of exceeding the lane line is estimated to be equal to 1. When the time exceeding the lane line is greater than the preset time, the weight value of the estimated time exceeding the lane line is decreased along with the increase of the time exceeding the lane line. In addition, the steering control force weight of the controller may include a lateral offset weight, a first percentage parameter, a predicted lane crossing time weight, and a second percentage parameter. The steering control force weight is equal to the lateral offset weight multiplied by the first percentage parameter minus the estimated lane crossing time weight multiplied by the second percentage parameter. The sum of the first percentage parameter and the second percentage parameter is 100%. The vehicle is spaced from the lane-fitting curve by a lateral offset distance, and the lateral offset weight value increases as the lateral offset distance increases. The steering control force weight of the controller can be a predicted weight value of the time exceeding the lane line, and the controller calculates the time exceeding the lane line according to the speed, the acceleration and the yaw rate. When the time of exceeding the lane line is less than or equal to a preset time, the weight value of the time of exceeding the lane line is estimated to be equal to 1. When the time exceeding the lane line is greater than the preset time, the weight value of the estimated time exceeding the lane line is decreased along with the increase of the time exceeding the lane line. Furthermore, the steering apparatus may include a current control mechanism, a driving mechanism, and a steering mechanism, wherein the current control mechanism provides a driving current, and the current control mechanism controls the magnitude of the driving current according to the steering control force weight. The driving mechanism is electrically connected with the current control mechanism and is controlled by the driving current. The steering mechanism is driven by the driving mechanism, and the steering mechanism controls the steering of the vehicle according to the driving current. Further, the aforementioned drive current may become larger as the steering control force weight increases, and the drive current may become smaller as the steering control force weight decreases. In addition, the vehicle dynamic parameters may include vehicle speed, acceleration, yaw rate, turning angle, and driving torque. Furthermore, the preview weight within the preview distance may be greater than the preview weight outside the preview distance.
According to an embodiment of the present invention, a method for controlling a vehicle lateral direction of a weight-adjustable lane model includes a front-view capturing step, an image processing step, a control force weight generating step, and a vehicle steering control step. Wherein the front image capturing step is to provide a camera to shoot towards the front of the vehicle and output a front image data. The image processing step is to provide an image processing device to receive and analyze the front picture data to obtain a plurality of lane feature points, and to establish a lane fitting curve according to the lane feature points and a preview weight. In addition, the control force weight generating step is to provide a controller to calculate and generate a steering control force weight according to the lane fitting curve and a plurality of vehicle dynamic parameters. The controller includes a look-ahead distance, and the look-ahead weight is varied according to a change in the look-ahead distance. And the vehicle steering control step is to provide a steering device to control the steering of the vehicle according to the steering control force weight.
Therefore, the vehicle transverse control method capable of weight-modulating the lane model can adaptively modulate the driving current according to the weight of the steering control force, not only can smoothly switch the steering control force, but also can improve the safety and the comfort degree of the switching process.
Other examples of the foregoing embodiments are as follows: in the control force weight generating step, the steering control force weight of the controller is a lateral offset weight value. The vehicle is spaced from the lane-fitting curve by a lateral offset distance, and the lateral offset weight value increases as the lateral offset distance increases. In addition, in the control force weight generating step, the steering control force weight of the controller may be an estimated time-to-lane-crossing weight, and the controller calculates an over-lane-crossing time according to the vehicle speed, the acceleration and the yaw rate. When the time of exceeding the lane line is less than or equal to a preset time, the weight value of the time of exceeding the lane line is estimated to be equal to 1. On the contrary, when the time exceeding the lane line is greater than the preset time, the weight value of the estimated time exceeding the lane line is decreased along with the increase of the time exceeding the lane line. Furthermore, in the control force weight generating step, the steering control force weight of the controller may be determined according to a lateral offset weight value and a maximum value of an estimated time-over-lane weight value. The vehicle is spaced from the lane-fitting curve by a lateral offset distance, and the lateral offset weight value increases as the lateral offset distance increases. The steering control force weight of the controller can be a predicted weight value of the time exceeding the lane line, and the controller calculates the time exceeding the lane line according to the speed, the acceleration and the yaw rate. When the time of exceeding the lane line is less than or equal to a preset time, the weight value of the time of exceeding the lane line is estimated to be equal to 1. When the time exceeding the lane line is greater than the preset time, the weight value of the estimated time exceeding the lane line is decreased along with the increase of the time exceeding the lane line. In addition, in the control force weight generating step, the steering control force weight of the controller includes a lateral offset weight value, a first percentage parameter, a predicted lane crossing time weight value and a second percentage parameter, and the steering control force weight is equal to the lateral offset weight value multiplied by the first percentage parameter minus the predicted lane crossing time weight value multiplied by the second percentage parameter. Wherein the first percentage parameter and the second percentage parameter total 100%. The vehicle is spaced from the lane-fitting curve by a lateral offset distance, and the lateral offset weight value increases as the lateral offset distance increases. The steering control force weight of the controller can be a predicted weight value of the time exceeding the lane line, and the controller calculates the time exceeding the lane line according to the speed, the acceleration and the yaw rate. When the time of exceeding the lane line is less than or equal to a preset time, the weight value of the time of exceeding the lane line is estimated to be equal to 1. When the time exceeding the lane line is greater than the preset time, the weight value of the estimated time exceeding the lane line is decreased along with the increase of the time exceeding the lane line. In addition, the vehicle steering control step may include a current control sub-step, a driving sub-step, and a steering sub-step, wherein the current control sub-step provides a current control mechanism to regulate a magnitude of a driving current according to the steering control force weight. The driving sub-step is to control a driving mechanism by using the driving current. The steering sub-step provides a steering mechanism driven by the driving mechanism to control the steering of the vehicle according to the driving current. In the vehicle steering control step, the drive current is increased as the steering control force weight increases, and the drive current is decreased as the steering control force weight decreases. In the control force weight generating step, the preview weight within the preview distance is larger than the preview weight outside the preview distance.
Drawings
FIG. 1 is a schematic diagram of a vehicle lateral control system with a weight-tunable lane model according to an embodiment of the present invention;
FIG. 2 is a schematic diagram showing an external appearance of the vehicle lateral control system of the weight-tunable lane model of FIG. 1;
FIG. 3 is a schematic diagram illustrating a pre-distance-to-lane model according to the present invention;
FIG. 4 is a schematic diagram showing a known lane-fitting curve to the present invention;
FIG. 5A is a diagram illustrating the preview weight according to the first embodiment of the present invention;
FIG. 5B is a diagram illustrating pre-view weights according to a second embodiment of the present invention;
FIG. 6 is a schematic view illustrating the steering apparatus of FIG. 1;
FIG. 7 is a schematic diagram depicting laterally offset weight values of the steering control force weight of FIG. 6;
FIG. 8 is a schematic diagram illustrating the estimated lane-crossing time weight exceeded for the steering control force weight of FIG. 6;
FIG. 9 is a flowchart illustrating a method for lateral control of a vehicle with a weight-adjustable lane model according to an embodiment of the invention;
fig. 10 is a flowchart illustrating a vehicle lateral control method for a weight-modulated lane model according to another embodiment of the invention.
Detailed Description
Various embodiments of the present invention will be described below with reference to the accompanying drawings. For the purpose of clarity, numerous implementation details are set forth in the following description. It should be understood, however, that these implementation details are not to be interpreted as limiting the invention. That is, in some embodiments of the invention, these implementation details are not necessary. In addition, for the sake of simplicity, some conventional structures and elements are shown in the drawings in a simple schematic manner; and repeated elements will likely be referred to using the same reference numerals.
Referring to fig. 1 to 8 together, fig. 1 is a schematic diagram illustrating a vehicle lateral control system 100 capable of weighting a lane model according to an embodiment of the invention. Fig. 2 is an external view of the vehicle lateral control system 100 of the weight-adjustable lane model of fig. 1. Fig. 3 is a schematic diagram illustrating a lane model corresponding to the look-ahead distance D according to the present invention. FIG. 4 is a schematic diagram showing a lane-fitting curve y of the present invention. FIG. 5A shows the preview weight w according to the first embodiment of the present inventionimage(xi) Schematic representation of (a). FIG. 5B shows the preview weight w according to the second embodiment of the present inventionimage(xi) Schematic representation of (a). Fig. 6 is a schematic view illustrating the steering apparatus 500 of fig. 1. FIG. 7 is a view showing the steering control force weight W of FIG. 6RSchematic diagram of the lateral offset weight value W1. FIG. 8 is a view showing the steering control force weight W of FIG. 6RIs a schematic diagram of the estimated lane crossing time weight value W2. As shown in the figure, the vehicle lateral control system 100 of the present invention is used for controlling a vehicle 110, and the vehicle lateral control system 100 of the present invention includes a camera 200, an image processing device 300, a controller 400 and a steering device 500.
The camera 200 is disposed on the vehicle 110, and the camera 200 photographs and outputs a front view data 210 toward the front of the vehicle 110. The front frame data 210 may be a two-dimensional or three-dimensional image that can be viewed by the camera 200. The image data 210 of the front view outputted from the camera 200 is provided to the image processing apparatus 300 for subsequent operation.
The image processing device 300 is connected to the camera 200 via signals, the image processing device 300 receives and analyzes the front frame data 210 to obtain a plurality of lane feature points 310, and the image processing device 300 obtains a preview weight w according to the lane feature points 310 and the preview weight wimage(xi) And establishing a lane fitting curve y. In detail, the image processing apparatus 300 includes a lane feature point identification unit 320, a lane featureA point weight adjusting unit 330 and a curve fitting unit 340. The lane feature point identification unit 320 is electrically connected to the camera 200 and receives the front frame data 210 to obtain a plurality of lane feature points 310. The lane feature points 310 correspond to lane lines in the front frame data 210 and are used to construct a lane model of the vehicle 110, and the lane feature points 310 are represented by coordinate information (x)i,yi) Is represented by, wherein the parameter xi、yiRespectively represent coordinate positions of the lane lines corresponding to the X-axis direction and the Y-axis direction, and the parameter i represents a positive integer from 1 to n. In addition, the lane feature point weight adjusting unit 330 is in signal connection with the lane feature point identifying unit 320 and the controller 400, and the lane feature point weight adjusting unit 330 receives the coordinate information (x) of the lane feature point 310i,yi) And calculating the preview distance D to obtain the preview weight wimage(xi). Preview weight wimage(xi) The weight of the lane model, i.e. the weight of the lane feature point 310. Preview weight wimage(xi) Will depend on the parameter xiMay vary from one another. Two examples are listed below to illustrate the preview weight w of the first embodimentimage(xi) Can be expressed by the following formula (1):
wherein a and b are self-defined parameters, a can adjust the preview weight wimage(xi) Slope of the waveform, b representing the preview weight wimage(xi) A distance parameter x of 0.5iAnd b is greater than the look-ahead distance D. The preview distance D of the first embodiment can be equal to 15m, a can be set to 1, b can be set to 22, and the preview weight wimage(xi) As shown in fig. 5A. As shown in FIG. 5A, the preview weight w within the preview distance Dimage(xi) Greater than preview weight w outside preview distance Dimage(xi). In addition, the preview weight w of the second embodimentimage(xi) Can be expressed by the following equation (2):
wherein c and d are self-defined parameters, and c is capable of adjusting the preview weight wimage(xi) Width of the waveform, d, adjustable preview weight wimage(xi) The slope of the waveform. The preview distance D of the second embodiment can be equal to 15m, c can be set to 8, D can be set to 4, and the preview weight wimage(xi) As shown in fig. 5B. In addition, the curve fitting unit 340 is in signal connection with the lane feature point weight adjusting unit 330 and receives the coordinate information (x) of the lane feature point 310i,yi) And a preview weight wimage(xi). The curve fitting unit 340 will determine the coordinate information (x) of each lane feature point 310i,yi) Multiplying by the preview weight wimage(xi) And fitting a lane fitting curve y by a weighted least squares method. The fitting operation process of the lane fitting curve y can be represented by the following equations (3) to (6):
[p q r]T＝[FT W F]-1 FT W Y (5)；
parameters p, q, and r can be obtained by weighted least squares through equations (3) to (6). Finally, the curve fitting unit 340 may calculate and output the lane fitting curve y ═ p + qx + rx2. Of course, the lane-fitting curve y is not limited to the second-order equation, and may be applied to equations of more than three orders. Therefore, the present invention utilizes the image processing apparatus 300 in combination with the controller 400 to give the lane feature point 310 a larger weight value through the position point of the preview distance D required for control, so as to perform accurate lane model calculation, thereby greatly improving the system controlAnd the accuracy of the lane-fitting curve y.
The controller 400 is in signal connection with the image processing device 300 and comprises a plurality of vehicle dynamic parameters 410 and a preview distance D, wherein the preview weight wimage(xi) According to the change of the foresight distance D. The controller 400 generates a steering control force weight W according to the lane-fitting curve y and the vehicle dynamic parameters 410RAs shown in fig. 6, 7 and 8. In detail, the controller 400 includes a look-ahead distance calculation unit 420, a lateral displacement compensation unit 430, a start-stop condition calculation unit 440, and a steering control force weight calculation unit 450. Wherein the look-ahead distance calculating unit 420 will first pass the vehicle dynamic parameters 410 (e.g. vehicle speed, steering angle of steering wheel) and the look-ahead time T of the vehicle 110FAnd calculating the pre-vision distance D. Preview time TFMust be set larger than the delay time of the control system, for example: a time delay caused when the camera processes an image or a time delay from a control command to an actual response. The look-ahead distance D is equal to the vehicle speed multiplied by the look-ahead time TF. The faster the vehicle speed, the longer the preview distance D. However, if the steering angle of the steering wheel is large, the system will reduce the preview time TFThe look-ahead distance D will be shorter. The look-ahead distance D may be one or more defined ranges, or a single or multiple values. Then, the preview distance D is transmitted to the image processing device 300, and the image processing device 300 calculates the corresponding preview weight w by using the formula (1) or (2)image(xi) Then, coordinate information (x) for each lane feature point 310i,yi) Multiplying by the preview weight wimage(xi) And fitting a lane fitting curve y by a weighted least squares method. Therefore, the invention uses the preview distance D and the corresponding preview weight wimage(xi) And calculating a lane model to obtain an accurate and more applicable lane fitting curve y for adjusting subsequent steering control force, so that the steering control force can be smoothly switched and the safety of switching control right is improved. In addition, the lateral displacement compensation unit 430 is in signal connection with the look-ahead distance calculation unit 420 and the curve fitting unit 340, and receives the lane simulation from the curve fitting unit 340The resultant curve y and the look-ahead distance D of the look-ahead distance calculation unit 420. Within the look-ahead distance D, the lateral displacement compensation unit 430 generates a steering angle θ through a lane-fitting curve y operation for the steering device 500. Furthermore, the start-stop condition calculating unit 440 is in signal connection with the curve fitting unit 340 and the steering device 500 and receives the vehicle dynamic parameters 410, the start-stop condition calculating unit 440 calculates a start-stop signal 442 according to the vehicle dynamic parameters 410 and the lane fitting curve y, and the start-stop signal 442 is transmitted to the steering device 500 for determining whether the steering device 500 is in a start state (controlled by the system; turn on) or a stop state (controlled by the driving; turn off). In addition, the steering control force weight calculation unit 450 is connected to the curve fitting unit 340 and the steering device 500 via signals and receives the vehicle dynamic parameters 410, and the steering control force weight calculation unit 450 generates a steering control force weight W according to the lane fitting curve y and the vehicle dynamic parameters 410R。
For example, referring to fig. 6 and 7 together, the steering control force weight W of the first embodimentRThe vehicle 110 is separated from the lane-fitting curve y by a lateral offset distance y _ offset, which is a lateral offset weight value W1, and the lateral offset weight value W1 increases as the lateral offset distance y _ offset increases. That is, when the system estimates that the vehicle 110 is far away from the lane-fitting curve y (i.e., the lateral offset distance y _ offset is small), the steering-control-force-weight calculating unit 450 provides a smaller steering control force weight WR(i.e., a smaller lateral offset weight value W1) to steer the driving leader and manually adjust the steering device 500; when the system estimates that the vehicle 110 is closer to the lane-fitting curve y (i.e., the lateral offset distance y _ offset is larger), the steering control force weight calculation unit 450 provides a larger steering control force weight WR(i.e., a larger lateral offset weight W1) allows the system to dominate the steering and automatically adjust the steering device 500, thereby allowing the vehicle 110 to return to the center of the lane. It should be noted that if the driver is actively about to leave the lane, the start-stop condition calculating unit 440 calculates a start-stop signal 442 according to the driving torque of the vehicle dynamic parameter 410 and the lane-fitting curve y, where the start-stop signal 442 is 0 to determine that the steering apparatus 500 is in the stopped state(steering by driving control; turn off). Conversely, if the driver does not leave the lane, the start-stop condition calculating unit 440 calculates a start-stop signal 442 according to the driving torque of the vehicle dynamic parameter 410 and the lane-fitting curve y, wherein the start-stop signal 442 is 1 to determine that the steering apparatus 500 is in the on state (steering controlled by the system; turn on).
Referring to fig. 6 and 8 together, the steering control force weight W of the second embodimentRThe estimated time-to-lane-crossing weight W2 is calculated by the controller 400 according to the vehicle speed, acceleration and yaw rate (yaw rate) to obtain a time-to-lane-crossing T, which represents the time the system estimates that the vehicle 110 will cross the lane-fitting curve y. When the time T exceeding the lane line is less than or equal to a preset time T1, the weight value W2 of the time exceeding the lane line is estimated to be equal to 1. When the lane line exceeding time T is greater than the preset time T1, the predicted lane line exceeding time weight value W2 decreases as the lane line exceeding time T increases. In other words, when the system predicts that the vehicle 110 will exceed the lane-fitting curve y in a short time, the steering control force weight calculation unit 450 provides a larger steering control force weight WR(i.e., a larger estimated lane time exceeding weight value W2) so that the system can control steering and automatically adjust the steering device 500; when the system predicts that the vehicle 110 will exceed the lane-fitting curve y after a certain time, the steering control force weight calculation unit 450 provides a smaller steering control force weight WR(i.e., a smaller estimated lane time exceeded weight W2), the driver is given the steering override to enable the driver to manually adjust the steering apparatus 500.
Referring to fig. 6, 7 and 8, a steering control force weight W of a third embodimentRIs determined according to the maximum value of the lateral deviation weighted value W1 and the predicted time-over-lane-line weighted value W2, i.e. the steering control force weighted value WRMax (W1, W2). That is, the steering control force weight WRThe interaction between the lateral offset weight W1 and the estimated time-to-lane-crossing weight W2 is considered, and the system considers both the lateral offset y _ offset and the time-to-lane-crossing T whenever either one of these conditions is metIncreasing the weight value, the system adjusts the weight of the steering control force. In addition, the lateral offset weight W1 may not change the opening size with vehicle speed, i.e., the shape of the lateral offset weight W1 of fig. 7 may not change with vehicle speed. The speed, acceleration, and yaw rate of the vehicle 110 are considered when the lane-line-time-exceeding weight value W2 is estimated. Therefore, the invention utilizes the steering control force weight W with multiple considerationsRTo adjust the magnitude of the control force applied to the steering device 500, and to smoothly switch the control force.
Referring to fig. 6, 7 and 8, a fourth embodiment of the steering control force weight WRIncluding a lateral offset weight W1, a first percentage parameter e, an estimated lane crossing time weight W2, and a second percentage parameter f. Steering control force weight WREqual to the lateral offset weight W1 multiplied by a first percentage parameter e minus the estimated time-to-lane-crossing weight W2 multiplied by a second percentage parameter f, wherein the sum of the first percentage parameter e and the second percentage parameter f is 100%, that is, WRW1 × e + W2 × f and f 1-e. The first percentage parameter e and the second percentage parameter f are adjustable parameters, which can be determined according to requirements. Therefore, the invention controls the force weight W through the multiple considered steeringRThe magnitude of the control force for intervention of the steering device 500 can be adjusted and planned flexibly according to the requirement, and the control force can be switched smoothly, so that the safety of switching the control right is improved, and the adverse effect and uncomfortable feeling of the sudden control force on driving are greatly reduced.
The steering device 500 is connected to the controller 400 and disposed on the vehicle 110, and the steering device 500 controls the steering force according to the steering control force weight WRControls the steering of the vehicle 110. Specifically, steering device 500 includes angle control section 510, speed control section 520, weight calculation section 530, steering control force determination section 540, current control section 550, drive section 560, and steering section 570. Wherein the angle control unit 510 is connected to the speed control unit 520 and the lateral displacement compensation unit 430 by signals, the angle control unit 510 receives the steering angle θ from the lateral displacement compensation unit 430, and the angle control unit 510 and the speed control unit 520 are used for calculating and generating the steering angleA current command 522. Furthermore, the weight calculation unit 530 is connected to the speed control unit 520 and the steering control force weight calculation unit 450 via signals, and the weight calculation unit 530 calculates the steering control force weight WRMultiplied by the current command 522 to output a current weight parameter. The steering control force determining unit 540 is in signal connection with the weight calculating unit 530 and receives the current weight parameter and the electric power assisted steering parameter EPS _ i, and the steering control force determining unit 540 determines the magnitude of the current applied to the driving mechanism 560 according to the electric power assisted steering parameter EPS _ i and the current weight parameter, so as to integrally adjust the magnitude of the control force involved in the electric power assisted steering (EPS). In addition, the current control mechanism 550 is in signal connection with the steering control force determining unit 540 and provides a driving current 552, and the current control mechanism 550 depends on the steering control force weight WRThe magnitude of the driving current 552 is regulated. Drive current 552 with steering control force weight WRBecomes larger as it increases, and the drive current 552 becomes larger with the steering control force weight WRDecreases and becomes smaller. In addition, the driving mechanism 560 is electrically connected to the current control mechanism 550 and controlled by the driving current 552, and the driving mechanism 560 in this embodiment is an electric motor. The steering mechanism 570 is driven by the driving mechanism 560, and the steering mechanism 570 controls the steering of the vehicle 110 through the driving mechanism 560 according to the driving current 552. The steering mechanism 570 of the present embodiment includes a steering wheel, a speed reducer, a gear, a transmission shaft, a tire, etc., and the details of the structure are not described herein since they are well known in the art. Therefore, the steering apparatus 500 of the present invention combines the electric power assisted steering, and determines the magnitude of the current applied to the driving mechanism 560 according to the electric power assisted steering parameter EPS _ i and the current weight parameter, so as to integrally adjust the control force involved in the electric power assisted steering, thereby increasing the smoothness of the switching control force.
Referring to fig. 1 and 9 together, fig. 9 is a flowchart illustrating a method 600 for lateral vehicle control with weight-modulated lane model according to an embodiment of the present invention. As shown, the method 600 for controlling the lateral direction of a vehicle with a weight-adjustable lane model includes a front view capturing step S12, an image processing step S14, a control force weight generating step S16, and a vehicle steering control step S18.
The front view capturing step S12 provides a camera 200 to shoot the front view of the vehicle 110 and output the front view data 210.
The image processing step S14 provides an image processing apparatus 300 for receiving and analyzing the front image data 210 to obtain a plurality of lane feature points 310, and according to the lane feature points 310 and the preview weight wimage(xi) And establishing a lane fitting curve y. Preview weight wimage(xi) See the above formulas (1) and (2). The fitting operation process of the lane fitting curve y can be referred to the aforementioned equations (3) to (6).
The control force weight generating step S16 provides a controller 400 to calculate and generate a steering control force weight W according to the lane-fitting curve y and the vehicle dynamic parameters 410R. The controller 400 includes a preview distance D, a preview weight wimage(xi) According to the change of the pre-vision distance D, as shown in FIGS. 5A and 5B. Wherein, as shown in FIG. 5A, the preview weight w within the preview distance Dimage(xi) Greater than preview weight w outside preview distance Dimage(xi). Further, the steering control force weight WRReferring to fig. 7 and 8, this may be a lateral offset weight W1, a predicted lane crossing time weight W2, or an interaction of both. In the first embodiment, the steering control force weight W of the controller 400 is described below with reference to four embodimentsRThe vehicle 110 is separated from the lane-fitting curve y by a lateral offset distance y _ offset, which is a lateral offset weight value W1, and the lateral offset weight value W1 increases as the lateral offset distance y _ offset increases, as shown in fig. 7. In the second embodiment, the steering control force weight W of the controller 400RThe predicted lane crossing time weighted value W2 is obtained, and the controller 400 calculates a lane crossing time T according to the speed, acceleration and yaw rate of the vehicle 110. When the time T exceeding the lane line is less than or equal to a preset time T1, predicting that the weighted value W2 of the time exceeding the lane line is equal to 1; when the lane line exceeding time T is greater than the preset time T1, the predicted lane line exceeding time weight value W2 decreases as the lane line exceeding time T increases. In addition, in the third embodiment, the steering control of the controller 400Weight of force WRAccording to the maximum value of the lateral deviation weighted value W1 and the predicted exceeding lane line time weighted value W2. While in the fourth embodiment, the steering control force weight W of the controller 400RComprises a lateral deviation weight value W1, a first percentage parameter e, a predicted time-over-lane weight value W2 and a second percentage parameter f, a steering control force weight WREqual to the lateral offset weight W1 multiplied by the first percentile e minus the estimated lane crossing time over weight W2 multiplied by the second percentile f, the sum of the first percentile e and the second percentile f being 100%.
The vehicle steering control step S18 is to provide a steering device 500 according to the steering control force weight WRControls the steering of the vehicle 110. In summary, the present invention provides a steering control force weight W with multiple considerationsRThe magnitude of the control force for intervention of the steering device 500 can be adjusted and planned flexibly according to the requirement, and the control force can be switched smoothly, so that the safety of switching the control right is improved, and the adverse effect and uncomfortable feeling of the sudden control force on driving are greatly reduced.
Referring to fig. 1 and 10 together, fig. 10 is a flow chart illustrating a vehicle lateral control method 600a of a weight-modulated lane model according to another embodiment of the invention. As shown, the method 600a for controlling the lateral direction of a vehicle with a weight-adjustable lane model includes a front view capturing step S22, an image processing step S24, a control force weight generating step S26, and a vehicle steering control step S28.
Referring to fig. 9, in the embodiment of fig. 10, the front image capturing step S22, the image processing step S24, and the control force weight generating step S26 are the same as the front image capturing step S12, the image processing step S14, and the control force weight generating step S16 in fig. 9, and are not repeated. Specifically, the vehicle steering control step S28 of the embodiment of fig. 10 includes a current control sub-step S282, a driving sub-step S284, and a steering sub-step S286, wherein the current control sub-step S282 provides a current control mechanism 550 to control the vehicle steering according to the steering control force weight WRThe magnitude of a driving current 552 is regulated. And the driving sub-step S284 controls a driving using the driving current 552And a mechanism 560. The steering sub-step S286 is to provide a steering mechanism 570 driven by the driving mechanism 560 to control the steering of the vehicle 110 according to the driving current 552. Further, drive current 552 is dependent on steering control force weight WRBecomes larger as it increases, and the drive current 552 becomes larger with the steering control force weight WRDecreases and becomes smaller. Thus, the driving current 552 of the present invention can be based on the steering control force weight WRThe adaptive modulation not only can smoothly switch the steering control force, but also can improve the safety and comfort level of the switching process.
As can be seen from the above embodiments, the present invention has the following advantages: firstly, an image processing device is combined with a controller, and a position point of a preview distance required by control is endowed with a larger weight value of a lane characteristic point so as to carry out accurate lane model calculation, and the effect of system control and the accuracy of a lane fitting curve can be greatly improved. Secondly, the magnitude of the control force of the intervention of the steering device is adjusted through the steering control force weight with multiple consideration, the control force can be flexibly adjusted and planned according to the requirement, and the control force can be smoothly switched, so that the safety of the switching control force is improved, and the adverse effect and uncomfortable feeling of the sudden control force on driving are greatly reduced. Thirdly, the driving current can be adaptively adjusted according to the weight of the steering control force, so that the steering control force can be smoothly switched, and the safety and the comfort degree of the switching process can be improved. And fourthly, under the interactive regulation and control of the preview weight and the steering control force weight, the system can smoothly switch the steering control force so as to solve the problems that sudden control force is easy to generate, unsafe conditions caused by the sudden control force are easy to generate and the driving control feeling is influenced in the process of switching the steering control force in the prior art.
Although the present invention has been described with reference to the above embodiments, it should be understood that various changes and modifications can be made therein by those skilled in the art without departing from the spirit and scope of the invention.
Claims (17)
1. A vehicle lateral control system for a weight-adjustable lane model for controlling a vehicle, the vehicle lateral control system comprising:
the camera is arranged on the vehicle, and shoots towards the front of the vehicle and outputs front picture data of the vehicle;
the image processing device is connected with the camera according to the image data signal in front of the vehicle, receives and analyzes the image data in front of the vehicle to obtain a plurality of lane characteristic points, and establishes a lane fitting curve according to the lane characteristic points and a preview weight;
the controller is connected with the image processing device according to the lane fitting curve signal and comprises a plurality of vehicle dynamic parameters and a preview distance, the preview weight changes according to the change of the preview distance, and the controller calculates and generates a steering control force weight according to the lane fitting curve and the plurality of vehicle dynamic parameters; and
and the steering device is connected with the controller according to the steering control force weight signal and is arranged on the vehicle, and the steering device controls the steering of the vehicle according to the steering control force weight.
2. The system of claim 1, wherein the steering force weight of the controller is a lateral offset weight, the vehicle is spaced from the lane-fitting curve by a lateral offset distance, and the lateral offset weight increases as the lateral offset distance increases.
3. The system of claim 1, wherein the steering force weight of the controller is a predicted lane crossing time weight, and the controller calculates a lane crossing time according to a vehicle speed, an acceleration and a yaw rate;
when the time exceeding the lane line is less than or equal to a preset time, the weight value of the estimated time exceeding the lane line is equal to 1;
when the time exceeding the lane line is greater than the preset time, the weight value of the estimated time exceeding the lane line is decreased progressively along with the increase of the time exceeding the lane line.
4. The system of claim 1, wherein the steering force weight of the controller is determined according to a lateral offset weight and a maximum predicted lane crossing time weight;
the vehicle and the lane fitting curve are separated by a transverse offset distance, and the weight value of the transverse offset is increased progressively along with the increase of the transverse offset distance;
wherein, the controller calculates to obtain the time exceeding the lane line according to a vehicle speed, an acceleration and a yaw rate; when the time exceeding the lane line is less than or equal to a preset time, the weight value of the estimated time exceeding the lane line is equal to 1; when the time exceeding the lane line is greater than the preset time, the weight value of the estimated time exceeding the lane line is decreased progressively along with the increase of the time exceeding the lane line.
5. The system of claim 1, wherein the steering force weight of the controller comprises a lateral offset weight, a first percentage parameter, a predicted lane-crossing time weight, and a second percentage parameter, the steering force weight is equal to the lateral offset weight multiplied by the first percentage parameter minus the predicted lane-crossing time weight multiplied by the second percentage parameter, and the first percentage parameter and the second percentage parameter sum to 100%;
the vehicle and the lane fitting curve are separated by a transverse offset distance, and the weight value of the transverse offset is increased progressively along with the increase of the transverse offset distance;
wherein, the controller calculates to obtain the time exceeding the lane line according to a vehicle speed, an acceleration and a yaw rate; when the time exceeding the lane line is less than or equal to a preset time, the weight value of the estimated time exceeding the lane line is equal to 1; when the time exceeding the lane line is greater than the preset time, the weight value of the estimated time exceeding the lane line is decreased progressively along with the increase of the time exceeding the lane line.
6. The system of claim 1, wherein the steering device comprises:
a current control mechanism for providing a driving current, wherein the current control mechanism regulates and controls the magnitude of the driving current according to the steering control force weight;
a driving mechanism electrically connected to the current control mechanism and controlled by the driving current; and
and a steering mechanism driven by the driving mechanism and controlling the steering of the vehicle according to the driving current.
7. The system of claim 6, wherein the driving current is larger as the steering control force weight is increased, and the driving current is smaller as the steering control force weight is decreased.
8. The system of claim 1, wherein the plurality of vehicle dynamics parameters include a vehicle speed, an acceleration, a yaw rate, a turning angle, and a driving torque.
9. The system of claim 1, wherein the look-ahead weight within the look-ahead distance is greater than the look-ahead weight outside the look-ahead distance.
10. A method for controlling a vehicle in a lateral direction of a vehicle with a weight-adjustable lane model is provided, which is characterized in that the method for controlling the vehicle in the lateral direction of the vehicle with the weight-adjustable lane model comprises the following steps:
a front picture capturing step, which is to provide a camera to shoot towards the front of the vehicle and output front picture data;
an image processing step, which is to provide an image processing device to receive and analyze the front picture data to obtain a plurality of lane characteristic points and establish a lane fitting curve according to the lane characteristic points and a look-ahead weight;
a control force weight generating step, namely providing a controller to calculate and generate a steering control force weight according to the lane fitting curve and a plurality of vehicle dynamic parameters, wherein the controller comprises a preview distance, and the preview weight changes according to the change of the preview distance; and
and a vehicle steering control step, which is to provide a steering device to control the steering of the vehicle according to the steering control force weight.
11. The method of claim 10, wherein in the step of generating the control force weight, the steering control force weight of the controller is a lateral offset weight value, the vehicle is spaced from the lane-fitting curve by a lateral offset distance, and the lateral offset weight value increases as the lateral offset distance increases.
12. The method as claimed in claim 10, wherein in the step of generating the control force weight, the steering control force weight of the controller is an estimated time-to-lane-crossing weight, and the controller calculates a time-to-lane-crossing according to a vehicle speed, an acceleration and a yaw rate;
when the time exceeding the lane line is less than or equal to a preset time, the weight value of the estimated time exceeding the lane line is equal to 1;
when the time exceeding the lane line is greater than the preset time, the weight value of the estimated time exceeding the lane line is decreased progressively along with the increase of the time exceeding the lane line.
13. The method as claimed in claim 10, wherein in the step of generating the control force weight, the steering control force weight of the controller is determined according to a lateral offset weight and a maximum value of a predicted time-over-lane weight;
the vehicle and the lane fitting curve are separated by a transverse offset distance, and the weight value of the transverse offset is increased progressively along with the increase of the transverse offset distance;
wherein, the controller calculates to obtain the time exceeding the lane line according to a vehicle speed, an acceleration and a yaw rate; when the time exceeding the lane line is less than or equal to a preset time, the weight value of the estimated time exceeding the lane line is equal to 1; when the time exceeding the lane line is greater than the preset time, the weight value of the estimated time exceeding the lane line is decreased progressively along with the increase of the time exceeding the lane line.
14. The method of claim 10, wherein in the step of generating the control force weight, the steering control force weight of the controller comprises a lateral offset weight, a first percentage parameter, a predicted lane crossing time weight and a second percentage parameter, the steering control force weight is equal to the lateral offset weight multiplied by the first percentage parameter minus the predicted lane crossing time weight multiplied by the second percentage parameter, and the sum of the first percentage parameter and the second percentage parameter is 100%;
the vehicle and the lane fitting curve are separated by a transverse offset distance, and the weight value of the transverse offset is increased progressively along with the increase of the transverse offset distance;
wherein, the controller calculates to obtain the time exceeding the lane line according to a vehicle speed, an acceleration and a yaw rate; when the time exceeding the lane line is less than or equal to a preset time, the weight value of the estimated time exceeding the lane line is equal to 1; when the time exceeding the lane line is greater than the preset time, the weight value of the estimated time exceeding the lane line is decreased progressively along with the increase of the time exceeding the lane line.
15. The method of claim 10, wherein the step of controlling the steering direction of the vehicle comprises:
a current control sub-step, which provides a current control mechanism to regulate and control the magnitude of a driving current according to the steering control force weight;
a driving sub-step, which utilizes the driving current to control a driving mechanism; and
a turning sub-step, which provides a turning mechanism driven by the driving mechanism to control the turning of the vehicle according to the driving current.
16. The method as claimed in claim 15, wherein in the step of controlling the vehicle steering, the driving current is increased as the steering force is increased, and the driving current is decreased as the steering force is decreased.
17. The method as claimed in claim 10, wherein in the step of generating the control force weight, the pre-sight weight within the pre-sight distance is greater than the pre-sight weight outside the pre-sight distance.
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| GB0317949D0 (en) * | 2003-07-31 | 2003-09-03 | Trw Ltd | Sensing apparatus for vehicles |
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| CN101282853A (en) * | 2005-10-07 | 2008-10-08 | 罗伯特·博世有限公司 | Driver assistance system |
| CN102481952A (en) * | 2009-08-21 | 2012-05-30 | 罗伯特·博世有限公司 | Method and control device for robustly detecting a lane change of a vehicle |
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