| CPC G08G 1/167 (2013.01) | 3 Claims |
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1. A dynamic regulation method for a lane changing decision point of a connected and automated vehicle (CAV)-dedicated lane in a diverging area of an expressway, applied to a one-way three-lane road, wherein three lanes are denoted as a first lane, a second lane, and a third lane, respectively, from the inside to the outside; the first lane is the CAV dedicated lane, and the second and third lanes are ordinary lanes; CAV denotes a connected and automated vehicle; only the CAV is allowed to travel on the CAV dedicated lane, vehicle types on the ordinary lanes are not restricted, a deceleration lane is provided at an outer side of the third lane, and an exit ramp is provided in front of the deceleration lane; wherein the dynamic regulation method comprises the following operations;
operation 1, establishing a plane coordinate system with an intersection point of a road centerline of the exit ramp and a road centerline of the deceleration lane as an origin, a traveling direction of vehicles as a positive direction of an x-axis, and a direction perpendicular to the x-axis as a y-axis;
using a road located upstream of the exit ramp with a length of S as a diverging area of the expressway;
providing a CAV dedicated lane dynamic regulation region on the CAV dedicated lane at an innermost side of an upstream road of the exit ramp, wherein the CAV dedicated lane dynamic regulation region is a rectangular region with the origin as a starting point, a horizontal coordinate xL on the x-axis as an end point, and a length of L; wherein:
the CAV dedicated lane dynamic regulation region includes a forced lane changing region and a free lane changing region;
the forced lane changing region is a rectangular region with the origin as a starting point, a horizontal coordinate xf on the x-axis as an end point, and a length of Lc;
the free lane changing region is a rectangular region with the horizontal coordinate xf on the x-axis as a starting point, a horizontal coordinate xL on the x-axis as an end point, and a length of Lf;
providing a diversion ratio detection region of a length Lb on the one-way three-lane road of the upstream road of the CAV dedicated lane dynamic regulation region, wherein the diversion ratio detection region is a rectangular region with the horizontal coordinate xL on the x-axis as a starting point, a horizontal coordinate xb on the x-axis as an end point, and S>L+Lb;
operation 2, collecting vehicle information of the one-way three-lane road at time t, including a count of vehicles passing through a certain section of the one-way three-lane road within a unit time period, and positions, speeds, and accelerations of the vehicles;
operation 3, determining whether total traffic flow Q(t)≥Qh on the one-way three-lane road at the time t is valid; in response to determining that the total traffic flow Q(t)≥Qh on the one-way three-lane road at the time t is valid, performing operation 4; and in response to determining that the total traffic flow Q(t)≥Qh on the one-way three-lane road at the time t is not valid, performing operation 10; wherein Qh denotes a road traffic flow threshold for dynamic regulation;
operation 4, collecting a count of CAVs mtotal(t) in the diversion ratio detection region at the time t, and counting a count of CAVs msr(t) in the diversion ratio detection region about to leave their own lanes and enter the exit ramp at the time t;
operation 5, calculating a vehicle diversion ratio λsr(t) at the time t using formula (1);
 operation 6, denoting an ith CAV in the first lane at the time t qi1(t), and determining an optimal lane changing decision point position li,opt(t) of the ith vehicle qi1(t) in the first lane within the CAV dedicated lane dynamic regulation region at the time t;
operation 6.1, calculating an optimal lane changing decision point position li,sms(t) of the ith vehicle qi1(t) in the first lane based on traffic efficiency within the CAV dedicated lane dynamic regulation region at the time t by using formula (2);
 wherein α1, α2, α3 and b denote four parameters of a cubic polynomial, li(t) denotes a lane changing decision point position of the ith vehicle qi1(t) in the first lane at the time t, and Sλsr[⋅] denotes a correspondence relationship between the lane changing decision point and the traffic efficiency;
operation 6.2, calculating an optimal lane changing decision point position li,tit(t) of the ith vehicle qi1(t) in the first lane based on a safety risk within the CAV dedicated lane dynamic regulation region at the time t by using formula (3);
 wherein β1, β2, β3, and d denote four parameters of a cubic polynomial, and Tλsr[⋅] denotes a correspondence relationship between the lane changing decision point and the safety risk;
operation 6.3, calculating an optimal lane changing decision point position li,opt(t) of the ith vehicle qi1(t) in the first lane within the CAV dedicated lane dynamic regulation region at the time t by using formula (4);
 wherein k1 and k2 denote two correction factors, and k1+k2=1;
operation 7, determining whether the ith vehicle qi1(t) in the first lane has a requirement for lane changing; in response to determining that the ith vehicle qi1(t) in the first lane has the requirement for lane changing, performing operation 7.1; and in response to determining that the ith vehicle qi1(t) in the first lane does not have the requirement for lane changing, performing operation 10;
operation 7.1, determining whether a horizontal coordinate xi(t)>li,opt(t) of the ith vehicle qi1(t) in the first lane at the time t is valid; in response to determining that the horizontal coordinate xi(t)>li,opt(t) of the ith vehicle qi1(t) in the first lane at the time t is valid, performing operation 7.2; and in response to determining that the horizontal coordinate xi(t)>li,opt(t) of the ith vehicle qi1(t) in the first lane at the time t is not valid, performing operation 10;
operation 7.2, determining whether xi(t)<xf is valid; in response to determining that xi(t)<xf is valid, performing operation 8; and in response to determining that xi(t)<xf is not valid, performing operation 9;
operation 8, denoting a rear vehicle in the second lane relative to the ith vehicle qi1(t) in the first lane as a rear vehicle qj+12(t) in the second lane; denoting a previous vehicle in the second lane relative to the ith vehicle qi1(t) in the first lane as a previous vehicle qj2(t) in the second lane;
in response to determining that the ith vehicle qi1(t) in the first lane satisfies formula (5), changing the ith vehicle qi1(t) in the first lane from the first lane to the second lane, and performing the operation 10; and in response to determining that the ith vehicle qi1(t) in the first lane does not satisfy the formula (5), keeping the ith vehicle qi1(t) in the first lane travelling in the first lane, and performing the operation 10;
 wherein xj(t) denotes a horizontal coordinate of the previous vehicle qj2(t) in the second lane at the time t, xj+1(t) denotes a horizontal coordinate of the rear vehicle qj+12(t) in the second lane at the time t, and dsafe denotes a safety distance maintained by the ith vehicle qi1(t) in the first lane from the previous vehicle qj2(t) in the second lane and the rear vehicle qj+12(t) in the second lane when the ith vehicle qi1(t) in the first lane enters the second lane;
operation 9, determining a last lane changing point position xlast of the ith vehicle qi1(t) in the first lane by using formula (6); determining whether xi(t)<xlast is valid; in response to determining that xi(t)<xlast is valid, performing operation 9.1; and in response to determining that xi(t)<xlast is not valid, completing changing lane of the ith vehicle qi1(t) in the first lane by a manner of stopping and waiting, and performing the operation 10;
 wherein amax denotes a maximum emergency braking acceleration of the CAV and vi(t) denotes a speed of the ith vehicle qi1(t) in the first lane at the time t;
operation 9.1, obtaining a safety distance dbehind(t) maintained by the ith vehicle qi1(t) in the first lane within the forced lane changing region at the time t from the rear vehicle qj+12(t) in the second lane when the ith vehicle qi1(t) in the first lane changes to the second lane by using formula (7), and obtaining a safety distance dfront(t) maintained by the ith vehicle qi1(t) in the first lane within the forced lane changing region at the time t from the previous vehicle qj2(t) in the second lane when the ith vehicle qi1(t) in the first lane changes to the second lane by using formula (7);
 wherein Lbehind(t) denotes a longitudinal distance between the ith vehicle qi1(t) in the first lane and the rear vehicle qj+12(t) in the second lane at the time t; Lfront(t) denotes a longitudinal distance between the ith vehicle qi1(t) in the first lane and the previous vehicle qj2(t) in the second lane at the time t; vj+1(t) denotes a speed of the rear vehicle qj+12(t) in the second lane at the time t; Δt denotes a time interval; η1 and η2 denote two parameters; and lveh denotes a vehicle length;
operation 9.2, determining whether Lbehind(t)≥dbehind(t) and Lfront(t)≥dfront(t) are valid; in response to determining that Lbehind(t)≥dbehind(t) and Lfront(t)≥dfront(t) are valid, changing the ith vehicle qi1(t) in the first lane to the second lane, and performing the operation 10; and in response to determining that Lbehind(t)≥dbehind(t) and Lfront(t)≥dfront(t) are not valid, performing operation 9.3;
operation 9.3, determining whether Lbehind(t)+Lfront(t)≥dbehind(t)+dfront(t) is valid; in response to determining that Lbehind(t)+Lfront(t)≥dbehind(t)+dfront(t) is valid, performing operation 9.4; and in response to determining that Lbehind(t)+Lfront(t)≥dbehind(t)+dfront(t) is not valid, decelerating the ith vehicle qi1(t) in the first lane and keeping the ith vehicle qi1(t) in the first lane traveling in the original lane, and performing the operation 10;
operation 9.4, determining whether Lbehind(t)≥dbehind(t) and Lfront(t)<dfront(t) are valid; in response to determining that Lbehind(t)≥dbehind(t) and Lfront(t)<dfront(t) are valid, decelerating the ith vehicle qi1(t) in the first lane until the safety distance of the ith vehicle qi1(t) in the first lane from the previous vehicle qj2(t) in the second lane is greater than dfront(t) and then changing the ith vehicle qi1(t) in the first lane to the second lane, and performing the operation 10;
determining whether Lbehind(t)<dbehind(t) and Lfront(t)≥dfront(t) are valid; in response to determining that Lbehind(t)<dbehind(t) and Lfront(t)≥dfront(t) are valid, accelerating the ith vehicle qi1(t) in the first lane until the safety distance of the ith vehicle qi1(t) in the first lane from the rear vehicle qj+12(t) in the second lane is greater than dbehind(t) and then changing the ith vehicle qi1(t) in the first lane to the second lane, and performing the operation 10;
determining whether Lbehind(t)<dbehind(t) and Lfront(t)<dfront(t) are valid; in response to determining that Lbehind(t)<dbehind(t) and Lfront(t)<dfront(t) are valid, decelerating the ith vehicle qi1(t) in the first lane and keeping the ith vehicle qi1(t) in the first lane traveling in the original lane, and performing the operation 10;
operation 10, assigning t+Δt to t, and determining whether t≥te is valid; in response to determining that t≥te is valid, regulation is completed; and in response to determining that t≥te is not valid, returning the process to the operation 2 and then performing sequentially with operations 2-10; wherein te denotes a total regulation duration, Δt denotes a time interval.
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