Smooth trajectory planning for manipulator of cotton harvesting machinery based on quaternion and B-spline

A planning method for manipulator of cotton harvesting machinery is proposed to accomplish smooth orientation adjustment in its task space. Quaternion is adopted to represent the orientation instead of the traditional homogeneous transformation matrix, and the corresponding conversion process is deduced. The smooth orientation trajectory is generated by interpolating key orientations with the quaternion three-dimensional spherical interpolation method. Key joint positions are solved with the inverse kinematics algorithm according to discrete orientations sampled with specific positioning accuracy of the manipulator terminal, and then smooth joint trajectories with stable start-stop motion and continuous jerk are obtained through the interpolation method based on five degrees B-spline. Simulation results show that, the proposed trajectory planning method supplied manipulators with smooth adjustment of orientation and stable movement of joints, which made it an effective solution for the smooth orientation planning problem of manipulators in the cotton harvesting machinery.