Research On Robot Assembly Theory And Method Of Round-Dectangle Hole Parts

Assembly is a very important part of the production process.The quality of the assembly often directly affects the quality of the final product.At present,most of the assembly work still needs to be done by manual assembly in industrial production,but manual assembly has the disadvantages of high work intensity,low work efficiency,high error rate and high cost.In response to these problems of manual assembly,the manufacturing industry has an increasingly urgent need to use robots instead of manually completing assembly tasks.Compared to manual assembly,robotic assembly not only improves assembly efficiency,but also has a wider range of applications for use in high temperature,radiation and vacuum environments.At present,in the field of robot assembly research,most of the research objects are the assembly of round hole parts and rectangle hole parts.In the actual production process,the application of round-rectangle hole parts is also very extensive,currently at home and abroad.There is still very little research on the assembly of such complex parts.In this paper,a new assembly strategy is proposed for the round-rectangle hole parts.Combined with the force/position control method,the assembly of such complex parts is studied.There are many kinds of round-rectangle hole parts.In order to ensure the generality and universality of the research,a basic form is extracted from the common round-rectangle hole parts as the research object,and its geometric characteristics are analyzed.Based on this,the configuration and combination design of the modular robot arm for assembly are determined.According to the assembly characteristics of the round-rectangle hole parts,the assembly contact state that may occur after the peg is inserted into the hole is summarized and classified.The contact force analysis method for the composite hole type parts is proposed,and the general expression of contact force analysis is derived.Based on the analysis of the contact force,the recognition calculation method and the posture adjustment strategy of the contact state are given.In this paper,the assembly process of a round-rectangle hole part is divided into three stages: the approach phase,the search phase and the insertion phase.In the approaching phase,the dynamic control strategy of PD feedback is added on the basis of dynamic feedforward to ensure that the mechanical arm can control the peg to quickly approach the hole according to the specified trajectory;in the search hole phase,the search strategy based on the force sensor feedback information is used.The mechanical arm controls the peg to make tentative contact with the hole,and uses the feedback force information to calculate the relative position and orientation relationship of the hole,and sequentially adjusts the position error along the x-axis,the position error along the y-axis and the angle error around the z-axis;in the insertion phase,an assembly strategy is proposed to identify the contact state based on the force information fed back by the force sensor,and then generate a pose adjustment scheme to complete the assembly task.The entire assembly process uses force/position control to achieve dynamic balance of position and contact force to avoid assembly failure due to excessive contact force.In this paper,the assembly process simulation of the round-rectangle hole parts is carried out,and the virtual assembly environment is established in ADAMS.According to the assembly strategy proposed in this paper,the assembly controller is built in MATLAB/Simulink.In the simulation,the assembly of a round-rectangle hole type with a clearance of 0.03 mm is realized.The simulation results show that the assembly strategy proposed in this paper can realize the robot assembly task of composite hole parts.