Research On Key Technologies Of Micro-assembly Sequence Planning And Equipment Efficient Development

Micro-assembly equipment has been widely used in the assembly tasks of micro parts.Quickly building an efficient and stable assembly system is an important way for enterprises to improve product quality,quickly occupy the market and enhance their core competitiveness.At present,the rapid development of micro-assembly equipment mainly focuses on three aspects: assembly sequence planning,assembly alignment strategy and manipulator motion planning.Assembly sequence planning determines the order of assembly of parts and provides a basis for subsequent assembly process development.At present,this part of the work mainly relies on manual analysis and lacks effective adaptive guiding principles.With the increase in product parts and the complexity of the structure,manual analysis is bound to fall into the bottleneck.In the case of certain hardware levels and control processing algorithms,the assembly accuracy of the assembly equipment depends on the selection of the assembly strategy.At present,the alignment of the assembly features is mostly sequential alignment.This assembly method cannot avoid the accumulation and transmission of errors.The operating arm has potential space interference problems in the assembly operation,and reasonable and safe motion planning of the operating arm is of great significance for improving assembly efficiency.This part still relies on manual proofreading to extend the development cycle.Therefore,this thesis studies the above three issues,the main contents include:Firstly,under the premise of fixed position and posture,this thesis nalyzes the positional relationship of parts and obtains the assembly sequence between parts,and then obtains the collection of parts which has “collision” between connection relationship and interference relationship or “high cohesion and low coupling”.Regard the collection of parts as the subassembly,it is assembled with other parts to provide an effective solution for simplifying the assembly process.According to the actual micro-assembly equipment and assembly tasks,analyze and quantitative the factors affecting the assembly sequence.And the greedy strategy is introduced.The greedy algorithm is used to directly obtain the complete assembly sequence,which provides the basis and suggestion for the development of assembly equipment and assembly process.After manual analysis,the assembled assembly sequence is reasonable and reliable.Secondly,use an assembly strategy that aligns the space to the digital model to avoid errors caused by sequential alignment.For the position and orientation problem of the part under occlusion and the contour deviation of the part and the template due to machining,the similar feature registration method is used to achieve the part matching.The design feature descriptor combines feature points to segment the model from the part outline and identify line features or curve features.Multi-feature registration is achieved using the principle of eigenvalue constraints and order consistency,and the Hausdorff distance is used to evaluate the matching effect of parts.The image is acquired by a microscopic vision experimental platform,which can match the complete part with the occluded part.Finally,the manipulators and static obstacles in the assembly space are modeled to simplify the solution space,the collision problem is transformed into a mathematical problem,and the collision detection algorithm is designed to ensure the safety and reliability of the motion.The genetic algorithm is improved according to the movement characteristics of the operating arm,and the motion evaluation function is designed and introduced into the planning algorithm to adapt the algorithm to the motion planning problem of the operating arm.Simulation experiments show that this method can obtain a safe motion plan.The research work in this thesis provides technical support for the efficient development of assembly equipment.