Technology Research Of Subtle Force Rendering For Virtual Assembly Based On GPS

In mechanical assembly,different geometric tolerances will lead to different assembly force requirements.Providing accurate assembly force is one of the important conditions to ensure assembly quality.Therefore,in the field of virtual assembly,in order to simulate the real assembly process,force feedback technology is one of the research hotspots in virtual assembly field.Realistic force rendering model(FRM)can provide users with more realistic assembly perception and improve assembly efficiency.However,the existing FRM do not systematically consider the influence of the geometrical errors,resulting in a large difference between the virtual and real assembly force perception.This paper is based on geometrical product specifications(GPS)theory,and focuses on the research and development of the FRM taking into account the influence of the geometric errors of the parts.The main contents are summarized as follows:Firstly,a construction method of Skin Model Shapes(SMS)for FRM is developed,including separating operation,discrete operation,analyzing operation and integrating operation.The method is specifically introduced by taking cylindrical surface and plane surface as examples.A visualizing method of the SMS is proposed.Height nephogram is used to indicate the contour profile of the SMS.Then,a FRM based on SMS is developed.A positing method for transition fit and interference fit is proposed,which includes altitude positing stage and position positing stage.The concepts of assembly space and tolerance space based on SMS are proposed,and the calculation methods of the two space are given.A FRM in constrained assembly stage is proposed,and is specifically introduced by taking shaft-bushing assembly and parallel key assembly as examples.Moreover,the FRM of bolt assembly is developed.The influence of geometrical errors on assembly torque is analyzed.A tolerance model in bolt assembly process is developed based on SDT theory.The process of the bolt assembly is divided into three stages: guiding stage,transition stage and linear stage.The FRM considering geometric errors is presented in stages.Finally,an experimental platform is built to verify the FRM proposed in this paper.A force measurement platform and A virtual assembly prototype system is built.An Objective control experiment and a subjective evaluation experiment is designed for verification.The experimental results show that the FRM proposed in this paper has a certain improvement in fidelity and practical application effect compared with the existing methods.