| CPC G08G 1/167 (2013.01) | 3 Claims |
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1. A method for lane changing decision for vehicles on expressways considering safety risks in a networked environment, wherein the method is applied to a unidirectional three-lane roadway in the networked environment, a deceleration lane is provided on an outermost side in a vehicular travel direction; and the deceleration lane and a lane area adjacent to the deceleration lane are designated as a diversion zone, an upstream section of the diversion zone is designated as a basic roadway, and the method comprises:
step 1, noting a target vehicle as j, noting a lane in which the target vehicle j is located as i, noting a left lane in which the target vehicle j is facing the vehicular travel direction as i−1, noting a right lane in which the target vehicle j is facing the vehicular travel direction as i+1, noting a direct front vehicle of the target vehicle j as j−1, noting a direct rear vehicle of the target vehicle j as j+1, noting a left front vehicle of the target vehicle j as j−1, noting a left rear vehicle of the target vehicle j as j+1, noting a right front vehicle of the target vehicle j as j−1, and noting a right rear vehicle of the target vehicle j as j+1;
step 2, collecting a position of the target vehicle j at a moment t, taking the position of the target vehicle j at the moment t as an origin, taking the vehicular travel direction as a positive direction of an x-axis, and making a plumb line of the x-axis over the origin as a y-axis to establish a coordinate system; and
determining whether the target vehicle j is on the basic roadway at the moment t, in response to a determination that the target vehicle j is on the basic roadway, proceeding to step 3; in response to a determination that the target vehicle j is not on the basic roadway, proceeding to step 10;
step 3, determining whether the target vehicle j at the moment t satisfies an equation (1), in response to a determination that the target vehicle j satisfies the equation (1), the target vehicle j generating a demand for lane change and proceeding to step 4; otherwise proceeding to step 13;
[xi−1,j−1(t)>xi,j−1(t)|xi+1,j−1(t)>xi,j−1(t)]&&Vi,j(t)>vi,j−1(t) (1)
wherein xi−1,j−1(t) denotes a position of the left front vehicle j−1 of the target vehicle j on the left lane i−1 at the moment t, xi,j−1(t) denotes a position of the direct front vehicle j−1 of the target vehicle j on the lane i at the moment t, xi+1,j−1(t) denotes a position of the right front vehicle j−1 of the target vehicle j on the right lane i+1, vi,1(t) denotes a speed of the target vehicle j on the lane i at the moment t, and vi,j−1(t) denotes a speed of the direct front vehicle j−1 of the target vehicle j on the lane i at the moment t;
step 4, determining whether the target vehicle j is on a middle lane of the unidirectional three-lane roadway, in response to a determination that the target vehicle j is on the middle lane of the unidirectional three-lane roadway, proceeding to step 5; in response to a determination that the target vehicle j is not on the middle lane of the unidirectional three-lane roadway, proceeding to step 9;
step 5, collecting intervals between the target vehicle j and a front vehicle and a rear vehicle on a lane that is switching into at the moment t to determine a type of lane change risk of the target vehicle j when switching lanes at the moment t and obtain a lane change risk factor of the target vehicle j at the moment t; wherein
if an equation (2) holds, it indicates that the target vehicle j satisfies a free-type left lane change at the moment t, and a left lane change risk factor is αl=α0, wherein α0 is a constant;
 where αi,j(t), vi,j(t), and xi,j(t) denote an acceleration, a speed, and a position of the target vehicle j on the lane i at the moment t, respectively; αti−1,j−1(t) and vi−1,j−1(t) denote an acceleration and a speed of the left front vehicle j−1 of the target vehicle j on the left lane i−1 at the moment t, respectively; ai−1,j+1(t), v1−1,j+1(t) and x1−1,j+1(t) denote an acceleration, a speed and the position of the left rear vehicle j+1 of the target vehicle j on the left lane i−1 at the moment t, respectively; and Δt denotes a lane change time interval;
if an equation (3) holds, it indicates that the target vehicle j satisfies a free-type right lane change at the moment t, and a right lane change risk factor is set as αr=α0;
 where ai+1,j−1(t) and vi+1,j−1(t) denote an acceleration and a speed of the right front vehicle j−1 of the target vehicle j on the right lane i+1 at the moment t, respectively; ai+1,j+1(t), vi+1,j+1(t), and xi+1,j+1(t) denote an acceleration, a speed, and a position of the right rear vehicle j+1 of the target vehicle j the right lane i+1 at the moment t; and
if an equation (4) holds, it indicates that the target vehicle j satisfies a low-risk type left lane change at the moment t, and the left lane change risk factor is αl=α1, wherein α1 is a constant and α0<α1;
 if an equation (5) holds, it indicates that the target vehicle j satisfies a low-risk type right lane change at the moment t, and the right lane change risk factor is set as αr=α1;
 if an equation (6) holds, it indicates that the target vehicle j satisfies a medium-risk type left lane change at the moment t, and the left lane change risk factor is set as αl=α2, wherein α2 is a constant, and α1<α2;
 if an equation (7) holds, it indicates that the target vehicle j satisfies a medium-risk type right lane change at the moment t, and the right lane change risk factor is set as αr=a2;
 if an equation (8) holds, it indicates that the target vehicle j does not satisfy a left lane change requirement at the moment t, and the left lane change risk factor is set as αl=α3, wherein α3 is a constant and α2<α3; and
 if an equation (9) holds, it indicates that the target vehicle j does not satisfy a right lane change requirement at the moment t, and the right lane change risk factor is set as αr=α3;
 step 6, determining whether the left lane change risk factor and the right lane change risk factor determined in the step 5 satisfy an equation (10), in response to a determination that the left lane change risk factor and the right lane change risk factor satisfy the equation (10), proceeding to step 7; and in response to a determination that the left lane change risk factor and the right lane change risk factor do not satisfy the equation (10), proceeding to the step 8;
αl=Δr<α3 (10)
step 7, calculating a left lane change direction factor βl and a right lane change direction factor βr using an equation (11), when βl>βr, the target vehicle j performing a left lane change and ending process at the moment t; when βl<βr, the target vehicle j performing a right lane change and ending the process at the moment t;
 step 8, when αl>αr, the target vehicle j performing the right lane change and ending the process at the moment t; when αl<αr, the target vehicle j performing the left lane change and ending the process at the moment t; and when αl=αr=α3, performing step 13;
step 9, when the target vehicle j is on the left lane or the right lane at the moment t, collecting intervals between the target vehicle j and the front vehicle and the rear vehicle on the lane that is switching into at the moment t to determine whether the target vehicle j performs a lane changing operation at the moment t;
step 9.1, when the target vehicle j is on the left lane at the moment t, in response to that an equation (12) holds, then the target vehicle j performing the right lane change and ending the process at the moment t; otherwise, performing step 13;
Δr<α3 (12)
step 9.2, when the target vehicle j is on the right lane at the moment t, in response to that an equation (13) holds, then the target vehicle j performing the left lane change and ending the process; otherwise, performing step 13;
αl<α3 (13)
step 10, when the target vehicle j is in the diversion zone at the moment t, determining whether the target vehicle j needs to drive away from the diversion zone; when the target vehicle j needs to drive away from the diversion zone, proceeding to step 11; otherwise proceeding to step 12;
step 11, when the diversion zone is located on the leftmost side of the vehicular travel direction of the target vehicle j, calculating αl according to the step 5, and then determining whether the equation (13) holds; in response to that the equation (13) holds, the target vehicle j performing the left lane change and ending the process at the moment t; otherwise, performing step 14;
when the diversion zone is located at the rightmost side of the vehicular travel direction of the target vehicle j, calculating αr according to the step 5, and then determining whether the equation (12) holds; in response to that the equation (12) holds, then the target vehicle j performing the right lane change and ending the process at the moment t; otherwise, performing step 14;
step 12, if the target vehicle j does not need to drive away from the diversion zone at the moment t, returning to the step 3 and executing in sequence;
step 13, after assigning t+Δt to t, returning to the step 2 and executing in sequence; and
step 14, after assigning t+Δt to t, in response to that an equation (14) holds, returning to the step 2 and executing in sequence; otherwise, the target vehicle j performing a forced lane change at the moment t, which refers to vehicles affecting steering of the target vehicle j at the moment t adjusting their own speeds to force the target vehicle j to change into the diversion zone;
xj(t+Δt)>xmin (14)
wherein x1(t+Δt) denotes the position of the target vehicle j at moment t+Δt, and xmin denotes a latest lane change position of the vehicle.
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