Study On Method For Analyzing Crushes Involved Damaged Vehicle Based On Photogrammetry

Traffic accident will generally lead to vehicle's impact crash, and part of kinetic energy of the damaged vehicles is transferred to deformation energy. EBS (Equivalent Barrier Speed) related to the magnitude of deformation energy is an important parameter for traffic accident reconstruction analysis. For evaluating EBS, it is indispensable process to survey the extent of the damaged vehicle's crash. Currently, the measurement method is still traditional and being done manually by the traffic accident authenticator with tape measure.The thesis presents a new method based on DLT (Direct Linear Transform) model of close photogrammetry to survey damaged vehicle. It requires that authenticators take photos from the damaged vehicle following some criterion, and then load the photos satisfying requirements into the PhotoCrash program developed by the author. Now via PhotoCrash with human-machine interactive interface, authenticator can build the damaged vehicle's DLT model according to these photos, pick up the 3D positional information of the vehicle, calculate the crash data, output 2D crash aerial view and evaluate the value of EBS. Compared to traditional method, this application consists of following advantages: high efficiency and perfect performance for surveying vehicle, low artificial error, high precision and good reappearance.This method introduces the DLT mathematic model, which takes the following errors into consideration: non-orthogonal error, scale disaccord error and one order nonlinear error. The DLT arithmetical model is studied to satisfy the precision requirement for surveying vehicle. And complete procedure is described on how to figure out the outer spatial coordinates of unknown points.In the thesis, the damaged vehicle is classified by accident type and damaged position. Calculation methods are studied on equivalent crash value of different kinds of damaged vehicles. In addition, the thesis illuminates mathematic model of the impact force and residual crash, and provides the experiential equations about EBS.This thesis introduces the design idea of damaged vehicle's impact crash analysis system in both hardware and software sides. Moreover, the system's hardware structure, selection of main components and programming of PhotoCrash software are presented in detail.Finally, the system's practicability in road traffic accident reconstruction analysis is validated by the application to real accidents.