Background: Traditional manipulator requires professionals to write control programs for
specific job requirements so that the end-effector of the manipulator can work following the control
instructions. However, the flexibility of the manipulator is not high under the control of off-line programming.
With the diversification of the job requirements, the complexity of the work environment
has gradually increased. Therefore, the relevant scholars focused their research on the automatic trajectory
planning method of the manipulator. They used some algorithms to plan optimal trajectories for
the manipulator to automatically avoid obstacles in the complex environment. Researches show that the
hybrid optimal trajectory with parameter optimization such as time, energy and impact can be planned
by automated programming under some constraint conditions. The trajectory planning is helpful to
improve the automation and working efficiency of manipulators for the development of intelligent
Objective: Providing references for researchers from related fields by reviewing recent advances of the
manipulator trajectory planning.
Methods: This paper reviews the latest patents and current representative articles related to the manipulator
trajectory planning. The key methods of some references are introduced in several aspects of the
algorithm, innovation and principle.
Results: Researches on the manipulator trajectory planning in recent 10 years are reviewed. The differences
between algorithms in latest patents and current articles are introduced and analyzed and the future
developments and potential problems of the manipulator trajectory optimization are discussed.
Conclusion: The manipulator trajectory planning reduces complicated operator and hard programming
tasks, improving the intelligence of robots and the work efficiency. Current researches focus on collision-
free, parameter-optimized and high-efficiency solution which can be used to solve the problem of
the end-trajectory planning of the manipulator in the complicated space with obstacles. The aspects that
need to be improved in the future include: algorithm reliability, operational security and intelligence,
human-computer interaction, efficient simulation, and so on. More patents on manipulator trajectory
planning should be invented.