Rapid Mechanism Modeling Method Based On Sketch And Its Application In Simulation Of Bus Suspension Dynamics

In the early stages of product design,sketches are an important way for designers to express inspiration.Sketch-based modeling technology makes full use of the powerful function of computer,and expresses the design idea of creative thinking freely and quickly.So it has become a research hotspot in computer graphics,design,engineering and other fields.Aiming at the problems of high modeling requirement,complicated steps and low efficiency in the process of bus suspension dynamics modeling,this paper proposes a mechanism modeling method based on sketching and is applied to the rapid modeling of front suspension of bus In the design,the front suspension model established by this method is applied to multi-body dynamics simulation and ride comfort analysis.This paper is divided into six chapters,the main contents are as follows:The first chapter summarizes the domestic and international research status of hand-sketched sketch analysis and recognition,3D-based sketch-based model generation,vehicle suspension dynamics simulation and ride comfort analysis,and gives the main contents and framework of this paper.The second chapter proposes a method of pretreatment and primitive recognition of mechanism sketch.According to the characteristics of the components and the characteristics of the connection,a simple mechanism of drafting is proposed.In this paper,we propose a segmentation method that takes into account both the speed characteristics and the minimum distance of the sketch,and divides the complex strokes that have multiple primitives into several subpictures that contain only a single basic primitive.Aiming at the recognition of the elements in the sketch of the mechanism,a linear recognition method based on linear twist and a circle recognition method based on the comparison of the upper and lower limit distance are proposed.Define the five primitives in the organization’s sketch to normalize the organization’s sketches.The third chapter researches the structural feature recognition and matching of the plane mechanism sketch.Firstly,a classification method of sketch primitive relation of plane mechanism is given.Then,the structural feature frame of plane mechanism sketch is defined.The fuzzy shape of component and the constraint relation among components are expressed accurately by structural feature frame.A method of feature recognition and matching of planar mechanism sketch structure based on attribute adjacency graph is proposed.By setting up the attribute adjacency diagram of plane mechanism,the standard mechanism diagram with the characteristic matching degree of the sketch structure is drawn.An example is given to illustrate the exact algorithm of the planar graphs ’attribute adjacency graphs’ complete matching and incomplete matching.The forth chapter proposes a modeling method of spatial composite mechanism based on multi-planar sketch input is proposed.This paper presents a simplified representation method of complex spatial combination mechanism.Through the structural features of structural simplification diagram,a number of sketch input planes are divided into spatial composition mechanism,and the mosaic relation of multiplanar sketch is defined.Through the coordinate transformation method,The two-dimensional coordinates of the sketch are transformed into three-dimensional coordinates of the space,and the key data of the front suspension modeling is obtained.The method of spatial combination mechanism modeling based on multi-plane sketch input is applied to the rapid modeling of BFC6120KD bus front suspension,and the front suspension mechanism model is obtained.The fifth chapter establishes the BFC6120KD bus multi-body dynamics vehicle model,and carries on the dynamic simulation and the ride comfort analysis.Based on the theoretical method and technology proposed in this paper,ADAMS/Car is used as the simulation platform to build the multi-body dynamics vehicle model of the bus and the random input road and pulse input pavement file.The vehicle model was subjected to dynamic simulation test at full load to evaluate the ride comfort of the bus.The sixth chapter summarizes the main research results and innovations of this paper,and looks forward to the future work and research direction.