Design Of Externally Mounted Cable Force Sensor And System Development By High Voltage Excitation

The steel cable is a common load-carrying component, has been widely applied to some fields such as bridges and huge building structures because of its flexibility and high strength, its health is closely related to the safety of the people. Therefore, the stress inspection of steel cables to judge their health status has great significance. The traditional detection methods of the cable force have some shortcomings and they are hard to meet the requirement of cable online monitoring. Based on magneto-elastic effect, a new measurement method of cable force was studied which used the structure of externally mounted sensor to implement the online measurement of cables on active duty.Firstly, based on existing researches, the measurement method based on the magneto-elastic effect was studied and the structure of the externally mounted cable force sensor was designed. The magnetic circuit and electric circuit excited by high voltage were designed and discharge characteristic was analyzed.Secondly, for the detection of magnetization properties of steel cable, the hardware of the waveform acquisition system was designed which mainly includes charge and discharge circuit of high voltage excitation, signal conditioning circuits of excitation current and induced voltage, dual synchronous high speed data acquisition circuit, ADC control circuit and FIFO cache circuit based on CPLD.Next, the embedded application software of the cable force detection system was developed by using Windows CE embedded operating system according to the principle of the cable force sensor excited by high voltage.The software mainly contains following modules:system initialization, charge and discharge control, FIFO driver of waveform dada acquisition, control of CPLD, data processing, graphic display of excitation and induction signal, data transmission by network port and etc.Finally, using the prototype of high voltage exciting cable force detection system, the cable force calibration test was made to an actual type of cable in the structure laboratory. The test results showed that the externally mounted cable force detection system has good sensitivity and linearity and thus has wide application prospect and popularization value. At the same time, the software and hardware of the system was verified by the test.