Trajectory Generation and Adjustment Method for Robot Manipulators in Human-Robot Collaboration

For trajectory planning of service robot manipulators in daily living environment with obstacles, a trajectory generation and adjustment method in human-robot collaboration is proposed. At first, an approach is designed to produce a trajectory with similar shape to the demonstrated one based on dynamic movement primitive (DMP) model. Here, the problem of shape distortion caused by multi-degree-of-freedom coupling is solved by projecting the 3D target point on a plane where the demonstration trajectory falls, then generating the 3D trajectory by using Rodrigues' rotation formula. Thus the shape character of the produced trajectory can be ensured in all directions. Secondly, the trajectory can be adjusted by inserting interactive points to meet the operation requirements in cases of complex environments with obstacles in different shapes, and then it is smoothened by dual parabolic interpolation algorithm. Lastly, an interactive interface is built in ROS (robot operating system) under the idea of human-robot collaboration. Operators can intuitively help a manipulator to generate and adjust the 3D trajectory of the end-effector in the environment with or without obstacles. Obstacle-avoidance experiments validate the intuitiveness and flexibility of the proposed approach, which can adapt to complex daily-living environment with multiple kinds of obstacles.