Research On Motion Trajectory Planning Of Four DOF Palletizing Robot

In the field of industrial automation and logistics, palletizing robot is the important equipment to improve the production efficiency. And the trajectory planning is the core work in robotic motion controlling. Based on four DOF joint-type palletizing robot and its trajectory planning, this thesis does the research on trajectory planning, aiming at the optimal multi-objective, such as time-optimal, pulsation-optimal and energy-optimal.And two methods were proposed as follow: one is a new two-step planning method with time-optimal and joints compliance control, the other is a kind of multi-objective optimal planning methods based on the factors of palletizing running environment.Firstly, to establish and analyze the model of robotic kinematics based on the D-H coordinate method. The expressions of direct and inverse kinematics solution are derived. After simulations by Adams, it builds a foundation for the following research on trajectory planning.Secondly, to do the research on two-step planning method with time optimal and joints compliance control. While analyzing the problem, the pause among joints, in the way of traditional time-optimal planning, and based on the premise of optimal time, this thesis uses the flexible asymmetric S-curve and linear interpolation to make the joints'jerk more gentle.Thirdly, to do the research on a flexible optimal multi-objective planning method.The factors of palletizing running environment are added into consideration and the optimal time, pulsation, energy are aimed. This thesis applies the 7th B-spline curve as the basic curve, and uses FAHP, the fuzzy analytic hierarchy process, to solve every objectives' weights. The NSGA-? algorithm is applied to get the set of solutions,and the modified TOPSIS method, the combination of TOPSIS(Technique for Order Preference by Similarity to an Ideal Solution) and the gray relational degree method, is used to select the best Pareto solution. So the optimal trajectory is obtained.Finally, to do palletizing experiment to verify the methods, the robotic software system is designed and implemented. And the repetitive positioning accuracy experiment and palletizing experiment verifies that the two methods above are correct and effective.The research shows that the two-step planning method with time-optimal and joints'compliance control can reduce the target joints' jerk while no reducing the total running effectiveness; and the optimal multi-objective planning method based on the factors of palletizing running environment is effective and flexible, and it is suitable for running environment variable and different palletizing needs and targets. And the method with the improved TOPSIS can help to get better the final trajectory than the TOPSIS. Totally,two trajectory planning methods above are significant for the motion controlling in four DOF joint-type palletizing robot.