Research On Embedded Capacitance Torque/Rotating Speed Sensing Technology

Torque/rotating speed are important indexes of evaluating dynamic vehicle transmissionsystem performance. Measuring the torque/rotating speed of drive shaft in the real timecorrectly is demanded widely in military and civilian areas. Directing at some problems suchas installation difficulty and lacking of theoretical guidance recently in domestic and overseastorque/rotating speed measurement methods, capacitance sensing technology testing methodwas proposed and discussed comprehensively in this paper.The method which is a combination of theoretical calculation, mathematical modeling,software simulation and simulated test calibration was used in this paper to discuss the basicprinciple, test scheme and error sources of the capacitance sensing technology. And someinnovative viewpoint was proposed then. The following paper is the studies content:First, according to a large volume of domestic and overseas literature about torque androtating speed testing method some problems in this area was included, which are the volumeof the testing instrument being larger, installation difficulty, and lacking of theoretical basis.And then future research consideration was oriented.Second, differential grid sensor structure was designed and installing hard in the testingenvironment was solved. Resolution of the signal and signal-to-noise ratio was improved. Thetheoretical basis was provided for sensor, which includes the following steps: Firstly, thesensor mathematical model was established by finite element method of numericalcomputation method; secondly electric field was abstracted using variation principle; thenarea was solved with linear interpolation division and true solution was obtained finally. Inaddition, the sensor mathematical model was further verified.And third, conventional sensor optimal design method was analyzed. Because of somesemi-quantitative and simplified optimal method could not solve practical problem, this paper got better result that reduced sensor development cycle and eased workload, using patternsearch and compound shape method in optimization algorithm, designing optimally sensor byMatlab Optimization Toolbox.Finally, the adapted-circuits were designed for sensor, which includes pulse widthmodulation circuit, filter circuit and storage circuit, etc. And simulator stand was establishedto simulate comprehensively the practical applications and to calibrate sensor. The liftingwavelet algorithm was used to reduce the noise of the measured signal.All the work including theoretical analysis and simulated experiment proved that gratingcapacitance transducer has reasonable structure，and it can be applied to practical projects.