Micro-force Measurement And Control System Based On The Principle Of Electrostatic Field

With the rapid development of technology, research has gone deep into the micro-and nano size, micro force measuring experiment instrument is applied more and morewidely, which has played a more and more important role especially in MEMS, microhardness test, nano materials research and experiments, biological sciences researchand application. Restricted by the standard weight processing technology and otherfactors, the minimum force which can be traceable and measurable is about mN in thedomestic, in the range of10-3N-10-4N. Therefore the development of a reliable andconvenient micro force measurement instrument to measure10-5N force or less hasbecome an urgent need.Through access to reference, the domestic and foreign research results aresummarized and compared, finally we use differential parallelogram flexible hingestructure, explore and verify the micro force measuring principle and scheme based onthe principle of electrostatic field through the experimental device. The main researchcontents and work are as follows:1. Complete the derivation of the principle using electrostatic to reproduce microforce based on the principle of virtual work and the principle of energy conservation ofenergy principle,analysis of the capacitive sensor requirements, and the structure, shapeand size of different capacitance sensor are compared, use Ansoft to establish thesimulation model of coaxial cylindrical capacitance sensor, and simulate thedistribution of electric field and electric potential and capacitance value.2. Elastic sensitive element in the measurement system is discussed, useAnsysWorkbench to simulate the stiffness and modal simulation of parallelogram.According to the creep of parallelogram flexible mechanisms we proposed differentialstructure.3. Introduce the measurement scheme of the system, analysis the function of mainmodule, design the corresponding software according to the measurement needs.4. The mathematical model is set up with system identification method ofparallelogram flexible hinge, including the model order and parameters identification.According to the demand of actual control system, using adaptive PID control algorithmto control the output voltage to balance the measured force.5. Build the test platform, complete the internal and external electrode coaxialdegree and device capacitance gradient measurement. Through the static electricitygeneration experiments, the measuring principle using electrostatic force to trace and measure micro force has been validated, the experimental results are consistent with theexpected results.Finally, we analysis the causes of error in each module, and puts forward somecorresponding measures according to the problems in the measurement system.