Research On Key Technologies Of Thermostatic Device With Precision Under MK

Since the scanning tunneling microscopy (STM) was invented in the early1980s, aseries of testing technology and equipments like microscopy with the resolution of theatomic weight class have been created. Moreover with the continuous developments ofNano technology, today people are urgent to own the testing equipment with nanometerresolution in a large size range. Based on the background of these applications, theMolecular Measuring Machine (M3) is proposed. To ensure measurement accuracy ofthe size with nanometer accuracy, the influence of temperature has become an importantfactor, so thermostatic device is an important component of M3to achieve target ofmeasuring in a wide range within the high-resolution and high-precision. Therefore thispaper research on the key technologies of thermostatic device and has importanttheoretical significance and practical value.Based on the background of the M3, the global structure of the M3is researched inthis paper including the operational environment and the structure of core institutionand vacuum system and vibration isolation system. Based on the background of aboveresearch, the structure of thermostatic device is designed and theoretical analysis of itsheat transfer process. This paper analyzes the measurement characteristics of platinumresistance temperature sensor in thermostatic device and designs the temperaturemeasurement circuit, also proposes the method based on excitation pulse current todecrease self-heating effect of platinum resistance, also designs the method of curvefitting and specific algorithm to correct the nonlinear error in platinum resistance. Basedon the ANSYS software, the temperature field is simulated to research its temperatureuniformity, and the changes of heat sources in core structure, the material emissivity ofthermostatic device and the size of temperature control shell are researched in order todetermine its influence on the temperature field. In addition, the control model of thethermostatic device and the nonlinear model of the actuator in thermostatic device areestablished, and the heating characteristic of the thermostatic device is researched.Based on the control requirements of thermostatic device, the control algorithm ofadaptive fuzzy PID with variable universe is applied in the thermostatic device. Base onthe MATLAB software, the control algorithms with different stretching factors aresimulated and eventually prove that the control algorithm of adaptive fuzzy PID withvariable universe based on stretching factor of fuzzy rules has better control effect,excellent immunity and adaptive capacity of changes by the system parameters in thetemperature control of the thermostatic device.