用于躲避转向操作的路径规划方法_4

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此,路径82选择为用于车辆62躲避物体74的碰撞避免 路径yAP。
[0187] 碰撞避免路径82以上面讨论的方式确定为五阶多项式方程:
[0188] yAp(x) =a5,APX5+a4,ApX4+a3,APX3+a2,APX 2+ai,APX+ao,AP? (41)
[0189] 对于0<t<tTTC并且其中3〇』卩,31』卩,32』卩,33』卩,34,和出』卩是未知系数。在碰撞避 免路径82的起始处的初始条件限定为:
[0190] yAp(0)=0? (42)
[0191] y7 ap(0)=0? (43)
[0192] 又"奶⑴)=2。2, (44)
[CM93]由初始条件和方程(42)-(44),所述未知系数ao,AP,ai,AP和a2,AP能确定为:
[0194] ao,AP = 0? (45)
[0195] ai,AP = 0? (46)
[0196] a2,AP = C2? (47)
[0197] 碰撞避免路径82的边界条件限定为:
[0198] yAP ( VxtTTC ) = y lane ( VxtTTC ) +DlC ? (48)
[0199] y7 AP ( VxtTTC = y7 lane ( VxtTTC ) ? (49)
[0200] y〃 AP( VxtTTC ) =y〃 lane (VxtTTC ),(50)
[0201 ]所述边界条件提供具有三个未知系数a3,AP,a4,AP和a5, AP的三个方程(48)-(50),其 可求解为:
[0202] C2 · (VxtTTC)2+a3,AP · (vxtTTc)3+a4,AP · (vxtTTc)4+a5,AP · (VxtTTC)5 = yiane(VxtTTC)+Dlc ? (51)
[0203] 2C2 · (vxtTTc)+3a3,AP · (vxtTrc)2+4a4,AP · (VxtTrc)3+5as,AP · (vxtTrc)4=y/lane(VxtTTc) ? (52)
[0204] 2C2+6a3,AP · (VxtTTC) + 12a4,AP · (VxtTTC)2+20a5,AP · (VxtTTC)3 = y〃:Lane(VxtTTC) ? (53)
[0205] 在碰撞避免路径80被求解后,并且对于横过移动物体的情况,所述算法随后计算 从路点78向原始车道66的中心线68的返回路径(RP),如在示意图60中由返回路径86标识 的。使用偏移Dlc,从路点78到初始车道66的中心线68的返回时间值t TTR可以估计为:
[0206] ?? = ?ττ?+ Δ TlxDlc/L? (54)
[0207] 其中Λ Tu(是典型的车道改变时间,诸如5或6秒。
[0208] 如上所述,返回路径86定义为五阶多项式方程:
[0209] yrp(x) = a5,RPX5+a4,RPX4+a3,Rpx3+a2,RPX 2+ai,Rpx+ao,Rp, (55) [0210]对于加。<^<^771?并且其中系数3(),1^,31,1^,32,1^,33,1^,34,1^和出,1^是未知的。
[0211] 返回路径86的初始条件限定为:
[0212] yRp(vxtrrc)= yAP(Vxtrrc), (56)
[0213] y'rp(vxtrrc) = y'AP(VxtTTC), (57)
[0214] y〃rp(vxtrrc) =y〃AP(VxtTTC), (58)
[0215] 并且返回路径86的边界条件限定为:
[0216] yRP(VxtTTR) = y lane (Vx tTTR), (59)
[0217] y' RP(VxtTTR) =y' W(VxtTTR), (60)
[0218] y7/RP ( VxtTTR) = y7/ lane ( VxtTTR) . (61)
[0219] 由于存在六个方程和六个未知系数&〇,1^,&1,1^,&2,1^,&3,1^,&4,1^和&5,1^,因此戶/| :述系 数可由方程(56)-(61)确定,并且返回路径86求解为:
[0220] aaiF+aLipCvxtTic)-^^ · (vxtTic)2aaip · (νχ?τκ:)3·+34?ρ · (νχ?τκ:)4·^5,ιρ · (vxtric)5=y^(vxtTTc) ,(62) [0221 ] ai,Rp^2a2,RP · (vxtTrc)+3a3,RP · (vxtTrc)2+4a4,RP · (vxtTTc)3+5as,RP · (vxtTTc)4=y/^(vxtTTc) (63)
[0222] 2a2,RP+6a3,RP · (vxtTTc) + 12a4,RP · (vxtTTc)2+20a5,RP · (VxtTTc)3 = y//Ap(vxtTTc) (64)
[0223] a〇,RP+ai,Rp(vxtTTc)+a2,RP · (vxtTTc)2+a3,RP · (vxtTTc)3+a4,RP · (vxtTTc)4+a5,RP · (VxtTTC ) 5 = y lane ( VxtTTC ) ? (65)
[0224] ai,Rp+2a2,RP · (Vxtrrc)+3a3,RP · (Vxtrrc)2+4a4,RP · (VxtTTC)3+5a5,RP · (Vxtrrc)4 = y lane (VxtTTC) (66)
[0225] 2a2,RP+6a3,RP · (VxtTTC) + 12a4,RP · (VxtTTc)2+20a5,RP · (VxtTTc)3 = VxtTTc) (67)
[0226] 上面的讨论是对于沿相对于车辆行驶方向的横向方向移动的物体74,并且因此仅 仅需要计算碰撞避免路径82和返回路径86来躲避物体74。然而,如果物体传感器22确定物 体在车辆62前方在碰撞路径中沿相对于车辆行驶方向的纵向方向上移动或者物体74太长 而不能通过碰撞避免路径82和返回路径86而躲避,那么所述算法计算碰撞避免路径82和返 回路径86之间的巡航路径(CP)。
[0227] 图4是与示意图60类似的示意图100,其中相同的元件采用相同的参考标记标识, 描绘了这样的情形,其中移动物体1〇2(在此为自行车)在车辆62前方行驶并且具有大体相 同的行驶方向。示出的巡航路径104邻近物体102,位于碰撞避免路径80和返回路径86之间, 其允许车辆62在物体102周围行驶,其中巡航路径104在路点78处开始并且以车道偏移Dlc遵 循车道边界。如所示出的,碰撞边界106在尺寸和形状上被修改以考虑物体102的移动方向。
[0228] 巡航路径104的长度通过巡航时间值tTTS来限定,巡航时间值tTTS由物体102的速度 和其方向确定为:
[0229] tTTS = ^ ^ (68)
[0230] 其中vx是车辆速度,vx,〇bs是物体102的速度,1是物体102的长度,而t margin是巡航时 间中的安全裕量。
[0231] 如上所述,巡航路径104限定为五阶多项式方程:
[0232] ycp(x) = a5,cpx5+a4,cpx4+a3,cpx3+a2,cpx 2+ai,cpx+ao,cp? (69)
[0233] 对于加。<^<加5并且其中系数3〇,。卩,31,。卩,32,。卩,323,。卩,34,。卩和出,。卩是未知的。
[0234] 巡航路径104的初始条件限定为:
[0235] yep(VxtTTC) =yAP(VxtTTC), (70)
[0236] y' cp(VxtTTC) =y' ap(VxtTTC), (71)
[0237] y〃cp(VxtTTC) =y〃AP(VxtTTC), (72)
[0238] 并且巡航路径104的边界条件限定为:
[0239 ] y CP ( VxtTTS ) = y lane (VxtTTS) +Dlc,(73)
[0240] y' CP(VxtTTS) =y' lane(VxtTTS),(74)
[0241 ] y〃CP(VxtTTS)=y〃lane(VxtTTS). (75)
[0242] 由于存在六个方程和六个未知数,所以巡航路径104通过从初始和边界条件计算 系数 ao, cp,ai, cp,a2, rp,a3, cp,a4, cp 和 as, cp 而确定或求解为:
[0243] ao,cp+ai.cp(VxtTTC)+a2,cp · (VxtTTC)2+a3,cp · (VxtTTC)3+a4,cp · (VxtTTC)4+as,cp · (VxtTTC)5 = yap (VxtTTC) (76)
[0244] ai,cp+2a2,cp · (Vxtrrc)+3a3,cp · (Vxtrrc)2+4a4,cp · (VxtTTC)3+5a5,cp · (VxtTTC)4 = y7 ap (vxtTTc) (77)
[0245] 2a2,cp+6a3,cp · (vxtTTc)+12a4,cp · (νχ?ττο)2+20a5,cp · (νχ?ττο)3 = y7/ap(νχ?ττο) (78)
[0246] ao,cp+ai,cp(VxtTTS)+a2,cp · (VxtTTS)2+a3,cp · (VxtTTS)3+a4,cp · (VxtTTS)4+a5,cp · (VxtTTS ) 5 = y lane ( VxtTTS ) (79)
[0247] ai,cp+2a2,cp · (Vxtirs)+3a3,cp · (Vxtirs)2+4a4,cp · (Vxtrrs)3十5a5,cp · (VxtTTS)4 = y lane (VxtTTS) ( 80 )
[0248] 2a2,cp+6a3,cp · (VxtTTS)+12a4,sp · (VxtTTS)2+20a5,cp · (VxtTTS)3 = y''iane(VxtTTS) (81)
[0249] 返回路径86随后由巡航路径104的终点以与上述方程(62)-(67)相同的方式计算, 其中采用相同的边界条件,但是采用不同的初始条件如下表示:
[0250] yRp(Vxtrrs) =ycp(Vxtrrs),(82)
[0251] y7 rp(VxtTTs) =y7 cp(VxtTTs), (83)
[0252] y〃rp(Vxtrrs) =y〃cp(Vxtrrs), (84)
[0253] ao,Rp+ai.Rp(vxtTTS)+a2.RP · (VxtTTS)2+a3,RP · (VxtTTS)3+a4,RP · (VxtTTS)4+a5,RP · (VxtTTs)5
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