关英姿, 宋春林, 董惠娟. 空间自由漂浮机器人对运动目标抓捕的路径规划[J]. 机器人, 2017, 39(6): 803-811. DOI: 10.13973/j.cnki.robot.2017.0803
引用本文: 关英姿, 宋春林, 董惠娟. 空间自由漂浮机器人对运动目标抓捕的路径规划[J]. 机器人, 2017, 39(6): 803-811. DOI: 10.13973/j.cnki.robot.2017.0803
GUAN Yingzi, SONG Chunlin, DONG Huijuan. Path Planning of the Free-floating Manipulator for Capturing a Moving Target[J]. ROBOT, 2017, 39(6): 803-811. DOI: 10.13973/j.cnki.robot.2017.0803
Citation: GUAN Yingzi, SONG Chunlin, DONG Huijuan. Path Planning of the Free-floating Manipulator for Capturing a Moving Target[J]. ROBOT, 2017, 39(6): 803-811. DOI: 10.13973/j.cnki.robot.2017.0803

空间自由漂浮机器人对运动目标抓捕的路径规划

Path Planning of the Free-floating Manipulator for Capturing a Moving Target

  • 摘要: 针对空间机械臂对运动目标的抓捕提出了一种分段的在线运动规划方法,重点解决机械臂可能遮挡立体视觉相机视线的问题,并满足抓捕时间要求.基于扩展卡尔曼滤波器(EKF)建立了目标运动状态估计器.对立体视觉相机的视线遮挡约束进行了数学建模.将机械臂向目标的接近过程分成2个阶段,在2个阶段中分别使用多约束环境下的滚动RRT(快速扩展随机树)方法和能够快速接近目标的比例导引算法,并根据对目标运动状态的估计精度自主切换运动段.同时考虑组合体的动力学耦合特性,在运动规划中限制了平台姿态角速度.利用数学仿真验证了本文的目标运动状态估计方法和运动规划方法.比例导引方法可能由于机械臂遮挡立体视觉相机观测视线而抓捕失败,而本文的分段运动规划方法对全部仿真情况都能成功抓捕目标.本文的分段运动规划方法能够对各个方向运动的目标进行有效的运动状态估计并快速可靠地抓捕,避免了因遮挡立体视觉相机观测视线引起的抓捕失败.基于目标运动状态估计的切换策略能够根据实际的目标运动情况在线自主地切换2个运动段,对运动状态未知的目标具有鲁棒性.

     

    Abstract: A segmented on-line motion planning method is proposed for the free-floating space manipulator capturing moving targets, mainly to settle the LOS (line of sight) blocking problem of the stereo vision system probably caused by the manipulator, and to satisfy the time requirements for the capturing. An estimator of target motion states is built based on extended Kalman filter (EKF). The LOS blocking constraint of stereo vision system is modeled. The process of approaching the target is divided into two stages. The rolling RRT (rapidly-exploring random tree) algorithm in multi-constraint environment and the proportional navigation algorithm for approaching the target quickly are used in the two stages respectively. The switching between the two stages is performed according to the estimated accuracy of the target motion autonomously. Moreover, the angular velocity of the carrier is limited in the path planning according to the dynamic coupling of the combination. Mathematical simulations are conducted to verify the estimator of target motion and the path planning method of the manipulator. The proportional navigation algorithm may fail to capture the target due to the LOS blocking of stereo cameras caused by the manipulator, while the segmented motion planning method in this paper succeeds in capturing the target in all simulation conditions. The proposed segmented motion planning method is able to estimate effectively the motion states of the target, and capture the targets moving to different directions quickly and reliably, to avoid capturing failures caused by the LOS blocking of stereo vision system. The switching strategy based on the estimation of target motion can switch autonomously between two stages according to the actual motion of the target online, and shows robustness to the targets with unknown movement states.

     

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