Research On Optimal Generation Method Of Field Test Sequence For CTCS-2 On-Board Equipment

CTCS-2 on-board equipment is a typical software-intensive safety-critical equipment.It must pass strict tests before being put into use to ensure its functional completeness and safety.As one of the important means to evaluate the system quality,the field test plays an important role in improving the safety of the system software.However,there are still several problems in the current research on the generation and optimization of field test sequences for CTCS-2 on-board equipment.In the process of generating field test sequences,on the one hand,estimating the execution distance for field test cases currently relies on human experiences.The method has strong subjectivity,which is difficult to objectively and scientifically measure the reasonable and effective range of its error,and it is very easy to cause test interruption due to unreasonable division of test sections.On the other hand,the generation quality and efficiency of field test sequence are generally low,which would cause the train to run with no tests been executed and high cost during the test process.Based on the above observation,this thesis conducts in-depth research on the above problems.The main contributions are as follows:(1)In order to estimate the execution distance of the field test case accurately,this thesis proposes a method that estimates the execution distance of field test cases based on the train dynamic states.A testing process model is proposed by analyzing all possible finite dynamic state changes of the train during test execution,and then turns it into a directed graph path.According to the dynamic model in the state transition,comprehensively considering the influencing factors such as the type and number of case steps,required line conditions,and driver response time,the running distance of the train in each state stage is calculated,and finally the execution distance of the field test case is obtained.The field test cases of CTCS-2 on-board equipment are taken as case study to run on the onboard testing platform.Results show that the method can estimate the execution distance effectively,which provides a strong basis for generating field test sequences in a reasonable and efficient way.(2)In order to improve the generation quality and efficiency of field test sequences,an optimized test sequence generation method is proposed based on greedy-backtracking strategy.By analyzing the generation principle of field test sequence,the definition of guard point is proposed.Taking the shortest execution distance of test sequence as the optimization goal,a sequence generation model based on guard point strategy is constructed,which is solved by the optimization algorithm based on greedy-backtracking strategy,so as to optimize the generation of field test sequence.The results show that this method can effectively reduce the number of test sequences and shorten the train’s unnecessary running distance,which is of great significance to improve the field test efficiency.(3)In order to solve the problem of expensive cost and low efficiency of manual compilation of test sequences,an assistive tool is designed and developed for CTCS-2on-board equipment field test sequence generation.The tool can complete the functions of train control engineering data management,test case data management,test case execution distance estimation,test sequence generation,test sequence visualization and statistical management.Compared with the manual field test sequences,the results of comparison show that this tool can effectively improve the generation efficiency and management level of test sequences,which provides a strong tool support for generating field test sequences of on-board equipment.