Design And Optimization Of The Hedge Trimming Manipulator

Hedgerow cutting is a onerous task of green conservation jobs in modern city,domestic research in the field of hedgerow cutting automation yielded some achievements.However,we are still not expected to see applicable trimming equipment even though lots of endeavors have been dedicated to the research field.To resolve this situation,this dissertation based on automatic cquipment achievements inland and abroad is dedicated to implement an automatic hedge trimming manipulator that can be applied in landscape and highway hedge trimming.The paper identified the mechanism scheme of joint type robot manipulator according to hedge trimming performance requirements.Then,a 3-D model of the manipulator was built in Pro/Engineer package.Besides,dynamics simulation of the hedge trimming manipulator constructed in Pro/Engineer and ADAMS was followed.In particular,the semi-sphere and cylindrical shape trimming processes were virtually operated in ADAMS,which yielded the driving forces and driving speed curves of each driving unit respectively.All these work had been done to provide basics for the selection of each component.Static strength analysis of the key components such as the base,the major arm and the truss arm was carried out based on force analysis of the manipulator on three typical working operations condition.Then,the strength,stiffness were checked and the worst operating condition was verified.Plus,the natural frequency of the major body was proved to be beyond the reach of vibration frequency triggered by the ground and the cutter unit through the modal analysis of key components.Transient dynamics analysis of the base in the worst operating condition was conducted,which identified the impact load is an important factor leading to structure damage.After that,fatigue analysis was conducted to find out the most fragile position of the base,and through which we predicted the fatigue life of the base.In the end,Static optimization of of multi-working condition was applied to the base.The optimal solution was proved to be feasible after verification.The selection of pruning manipulator parts was conducted and the physical prototype was built according to the analysis results.Then,the testing experimental platform was built for stress testing of the base.Optimization results proved to be reliable and effective by comparing FEM calculated results and experimental test values of the base testing points,in which the rusult showed that the relative error between the two cases was small.