改进恒定时间间隔算法的无人汽车的队列控制

Platoon control of unmanned vehicles based on improved constant time gap algorithm

针对无人汽车车队在附着系数较低的路面上行驶的纵向控制问题,提出考虑道路附着系数和本车无法持续获取前车加速度信息的最小安全车距的计算方法,以此来对传统的期望车间距的恒定时间间隔(Constant Time Gap,CTG)算法进行改进.然后,采用分层的结构设计队列控制系统,并通过对车队的队列稳定性进行分析,得出上层控制中的控制器增益的取值条件.最后,对一个由4辆车组成的车队进行仿真验证.结果表明:提出的改进恒定时间间隔算法可以在路面附着系数较低的情况下保证车队的队列稳定性,同时能够避免相邻两车间发生碰撞.在本车无法获取前车加速度信息且前车紧急制动的情况下,采用改进的恒定时间间隔算法的车队在行驶过程中的最大车间距偏差率为19%,低于应用传统方法时的最大车间距偏差率22.27%,且车间距误差随着时间的增长最终收敛至零.采用改进的恒定时间间隔算法的车队在行驶过程中车辆的加速度的最大值为0.75 m/s^(2),低于利用传统方法时的加速度的最大值0.91 m/s^(2),说明改进的恒定时间间隔算法可以保证车队的稳定行驶,并且具有较好的乘坐舒适性.

In view of the platoon longitudinal control of unmanned vehicle platoon driving on the road with low adhesion coefficient,the calculation method of the minimum safe distance,considering the road adhesion coefficient and the acceleration information of the front vehicle failing to be continuously obtained,is proposed as an improvement to the traditional Constant Time Gap(CTG)algorithm for the desired vehicle distance.Then,a hierarchical structure is used to design the platoon control system,and the platoon stability is analyzed to derive the conditions for the controller gain in the upperlayer control.Finally,a platoon of four vehicles is simulated and verified.The results show that string stability of the vehicle platoon can be guaranteed and collision between two cars can be avoided by the improved constant time gap algorithm when the road adhesion coefficient is low.In the case that the car cannot obtain the acceleration information of the front car and the front car brakes urgently,the maximum deviation rate of the platoon with the improved constant time interval algorithm is 19%dur‐ing the driving process,which is lower than the maximum deviation rate of 22.27%when the tradi‐tional method is applied,and the distance error of the platoon eventually converges to zero with the in‐crease of time.The maximum value of vehicle acceleration in the driving process of the platoon that uses the improved constant time interval algorithm is 0.75 m/s2,which is lower than the maximum value of acceleration 0.91 m/s2 using the traditional method.It shows that the stability of the platoon and higher driving comfort can be guaranteed by the improved constant time interval algorithm.