前视预瞄点增量PI控制的最速转弯路径规划

Incremental PI Control of Single Rudder Wheel AGV's Most Rapid Turning Path Based on Forward Looking Pre-sighting Points

摘要:

针对单舵轮 AGV 转弯慢及跟踪精度低问题,提出一种单舵轮 AGV 最速转弯路径规划方法,设计前视预瞄点增量 PI 控制(Incremental PI control ,IPI)算法实现最速转弯路径跟踪。 建立单舵轮 AGV 运动学模型,分析驱动轮与转弯路径曲率之间关系,设置前向预瞄距离,获得不同舵轮线速度下最小转弯半径和运行轨迹;探寻运行参数对累计误差的影响规律,提出前视预瞄点 IPI 控制方式;最后揭示等曲率圆弧在直线衔接处曲率跳变规律,遍历三阶Bézier 曲线簇对比获取最贴合极限转弯轨迹的控制点,建立最优控制点,相比于其他 Bézier 曲线簇路径跟踪时间,用时最短。 经实车验证,IPI 算法相比于纯跟踪算法(PP),车头与叉齿朝前精度分别提高约 23.98% 与 23.48% ;相比于模型预测控制(MPC),车头与叉齿朝前精度略有降低;但在最优控制点下相比于控制点重合时路径跟踪时间,PP 运行效率最高可提升 14.1% ,MPC 最高仅提升 17% ,而 IPI 最高提升 25.8% 。 IPI 算法在保证较高跟踪精度的同时,实现最速转弯路径规划,展示良好的综合性能.

Abstract:

Aiming at the problem of slow turning and low tracking accuracy of single steering wheel AGV, a path planning method for the fastest turning of single steering wheel AGV was proposed, the incremental PI control ( IPI) algorithm of forward-looking preview point was designed to realize the tracking of the fastest turning path.Firstly, the kinematics model of single steering wheel AGV was established, the relationship between the driving wheel and the curvature of the turning path was analyzed, and the forward preview distance was set to obtain the minimum turning radius and running trajectory at different steering wheel linear speeds.The influence of operating parameters on the cumulative error was explored, and the IPI control method of forward-looking preview point was proposed.Finally, the curvature jump law of the equal curvature arc at the straight line connection was revealed.The control points that best fit the limit turning trajectory were obtained by traversing the third-order Bézier curve cluster, and the optimal control point was established.Compared with other Bézier curve clusters, the path tracking time was the shortest.Compared with the pure tracking algorithm (PP), the forward accuracy of the front and fork teeth of the IPI algorithm was improved by about 23.98% and 23.48% , respectively.Compared with the model predictive control (MPC), the accuracy of the front and fork teeth was slightly lower.However, under the optimal control point, compared with the path tracking time when the control points coincided, the PP operation efficiency can be increased by up to 14.1% , the MPC can be increased by up to only 17% , and the IPI can be increased by up to 25.8%.The IPI algorithm achieved the fastest turning path planning and showed good comprehensive performance while ensuring high tracking accuracy.