We refer https://github.com/ros-industrial/universal_robot
This is the analytical solutions for UR robot.
Why we use this ?
Usually, Moveit! ,which uses KDL solver or some other plugins , can not meet our requirements if we want more IK solutions. But for UR5, we can easily get its analytical solutions to obtain all the IK solutions.
But this code does not consider about the collision for the robot itself.
Therefore, some solutions can not be used.
