Design And Development Of Wiring Harness Laying Quality Inspection Device For Rail Vehicles

As a national transportation artery,rail transit assumes a heavy transportation task in the national economic development and urbanization process.Since the reform and opening up with the rapid economic growth and progress of railroad technology,the rapid development of the Chinese rail transportation business has entered the electrical high-speed era,and rail transportation equipment technology is more and more complex.Due to the high requirements of electrical automation,information technology and intelligence of rail transportation equipment,there are a lot of wiring harness manufacturing and complex wiring construction work in rail transportation equipment manufacturing.As one of the key components of the locomotive,the quality of the wiring harness itself and the construction of the site layout has a direct impact on the normal operation and safety of the train,so it is important to carry out quality inspection of the wiring harness.Due to the high labor cost,low detection efficiency and the high error rate of the traditional wiring harness quality inspection method,the laying quality of the wiring harness is difficult to ensure,and the safety and reliability of vehicle operation is a hidden danger,therefore,this dissertation proposes the research topic of wiring harness laying quality inspection device in the context of rail transit rolling stock manufacturing.Firstly,the current development status of wire harness inspection technology at home and abroad are thoroughly studied and analyzed,and the failure modes of wire harnesses and the basic content and methodological principles of wire harness inspection are explained.On this basis,the general framework of wire harness inspection is proposed in conjunction with the basic inspection needs of the actual site’s wire harness construction.The detection system is mainly composed of two parts: the signal source side and the signal detection side.Both devices use the powerful and cost-effective STM32F103C8T6 chip as the main control chip.To check the conductivity of the harness,the signal source is responsible for generating multiple square waves signals with different duty cycles,which are sent to the detection end via the harness.The detection end determines the conductivity,disconnection,short circuit,and interleaving of the harness by detecting the duty cycle of the respective received signals.To check the on-resistance of the wire harness,a constant current source is designed at the signal source end,and the voltage drop through the wire harness is measured by the detection end,which can calculate the on-resistance value of the wire harness.The wire harness insulation resistance test is to inject high voltage into the wire harness and calculates the insulation resistance value of the wire harness by measuring the leakage current of the insulation layer.In order to achieve the above functions,this dissertation completes the detailed design of the signal source side and signal detection side hardware circuit of the wire harness detection system,where the signal source side circuit design includes a signal generator,constant current source,high voltage DC source,wireless communication,touch display,RS-485 interface circuit,etc.The system software design completes the program flow design of the harness conduction detection module,harness conduction resistance detection module,harness insulation resistance detection module,communication module and touch screen human-machine interface.A comprehensive test of the designed wiring harness inspection system was conducted after the above work was completed.Firstly,the output functions of the power supply module and the signal source module were tested.The test results showed that the power supply module could provide the voltage required by the system and the signal source module could output waveforms normally.The communication function was then tested,and the test results showed that both the Wi-Fi module and the touch screen were able to achieve normal data transmission.Finally,the test environment was set up and the actual function of the harness testing system was tested according to the testing process.The results of multiple tests show that the testing system can complete the performance testing of the harness,and the test results can be displayed visually through the touch screen,and the results are reliable and have some practical value.