Dynamic Characteristics Analysis And Optimization Of Palletizing Robot

Stacking automatically with industrial robots takes unmatched advantage inrapidity, accuracy, continuity and consistency over manual stacking. As typicalindustrial robots palletizing robot, after30years of development, has become a realmechatronic automation system. The mechanical design, control systems andpalletizing trajectory planning of palletizing robots have reached a more mature level.However, the accelerating pace of industrial production and constantly improving ofpalletizing requirements (such as positioning accuracy, stacking stableness, etc.), israising more stringent requirements to the work speed and dynamic performance ofpalletizer. The design of palletizing robots has developed from the traditional static,rigid stage, to dynamic and flexible one.Based on this background, this paper carried out to optimize the dimensionparameter of palletizing robot in order to improve its dynamic characteristics.First, geometry of each rod parts (including two arms and three manipulator rods)has been reasonably simplified, and the final design parameters was reduced into20.After been simplified, the lever-type parts were divided into multiple spatial beamelements. The unit arrays have been got after importing each of three complex parts(base, waist and wrist) into ANSYS software. The rigid parts such as hinge shaftcomponents or the parts with not too large geometry were treated as a centralizedquality; flexible joints treated as torsion springs. So far the finite element model ofrobot has been get.On the other hand, typically palletizing process was selected, and the wholeprocess was divided into36segments of transient, during which the robot wereconsidered as a fixed structure. Transient Response Analysis of robot transformed intothe elastic dynamic analysis of the fixed structure. Introducing the methods of dynamicanalysis of structures such as modal analysis, modal truncation, etc., natural frequencyof the system within the transient period can be derived. The system responds in eachtransient were solved by stepwise integration method.Considering the three requirements, high fundamental frequency, high positioningaccuracy and low torque, proposed by the topic, an optimization indicator of systemdynamic performance were proposed using the weighting method. For this indicator,using gradient optimization ideas for reference,20design parameters to be modified inorder to obtain optimal or say better dynamic performance.Finally, the finite element modelling, elastic dynamic analysis, optimizationanalysis above were implemented in MATLAB, which made the whole cycle of analysis, optimization, model modification, re-analysis and re-optimization can beautomatically performed in the same software environment, until the differencebetween adjacent indicator was no longer obvious.After the optimizing of palletizing robot, with the new combination of parameters,joint torque was essentially the same as before, the system baseband and thedisplacement rigidity of wrist has been significantly improved.