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The Demand for circulating cooling water (CCW) with high temperature stability and a quick response to temperature control is essential for precision engineering, so a dynamic thermal filtering method is proposed in this paper. Some CCW is bypassed, blocked, and used as a thermal capacity medium, and the temperature fluctuation of CCW is significantly reduced by heat exchanging with the medium. The temperature of the medium dynamically follows the set value of the CCW temperature by real time updating, and so realizes a quick CCW temperature control response. The attenuation ratio of temperature fluctuation was derived, theoretically validating the effectiveness of the method. The experimental results indicate that a CCW temperature fluctuation attenuation ratio of tens of dB (&minus, 3.47 dB, &minus, 6.91 dB, &minus, 10.97 dB and &minus, 15.28 dB corresponding to temperature fluctuation frequencies of 0.01 Hz, 0.025 Hz, 0.053 Hz and 0.105 Hz, respectively) is achieved by the proposed method. The updating time of thermal capacity medium is 82 s, which means that the temperature fluctuation attenuation remains functionally valid when the set value of CCW changes. The proposed method is low cost in operation and provides an effective approach to satisfy the challenging demand for CCW with high stability and a good dynamic temperature control performance.

For precision measurement of miniature internal structures with high aspect ratios, a spherical scattering electrical field probe (SSEP) is proposed based on charge signal detection. The characteristics and laws governing surface charge distribution on the probing ball of the SSEP are analyzed, with the spherical scattering electrical field modeled using a 3D seven-point finite difference method. The model is validated with finite element simulation by comparing with the analysis results of typical situations, in which probing balls of different diameters are used to probe a grounded plane with a probing gap of 0.3 &mu, m. Results obtained with the proposed model and finite element method (FEM) simulation indicate that 31% of the total surface charge on a ϕ1 mm probing ball concentrates in an area that occupies 1% of the total probing ball surface. Moreover, this surface charge concentration remains unchanged when the surface being measured varies in geometry, or when the probing gap varies in sensing range. Based on this, the SSEP has realized approximate point probing capability with a virtual &ldquo, needle&rdquo, of electrical effect. Together with its non-contact sensing characteristics and 3D isotropy, it can, therefore, be concluded that the SSEP has great potential to be an ideal solution for precision measurement of miniature internal structures with high aspect ratios.

Electromagnetic actuators that produce high linearity driving force are key components in active vibration isolation. In this paper, a design of high linearity electromagnetic actuator is proposed. Scheme of double closed magnetic circuits is used to ensure the linearity of magnetic flux density and rectangular structure is adopted to ensure the processing and assembly precision. The magnetic circuits of electromagnetic actuator are modeled using lumped parameter magnetic circuit modeling method, validated by simulation, and optimized to obtain improved performance. Experimental results show that magnetic flux density of 293.2mT and non-linearity of} 0.37% is achieved.

Linearity and resolution of current drivers are two factors that limit control accuracy and dynamic response accuracy of linear electromagnetic actuators in precision active and semi-active micro-vibration isolation systems. In this paper, a high linearity bidirectional current driver with resolution, AC ripple and stability in the order of $\mu$A is proposed. Complementary power MOSFET is used to produce bidirectional driver current and over-current protecting circuit is used to limit the amplitude of output current and prevent high output current from damaging power MOSFET and load resistance. Design of MOSFET heat dissipation is theoretically analyzed and experimental setup is established to validate performance of the proposed current driver. Experimental results show that resolution of 30$\mu$A, nonlinearity of 0.005%, stability of 150$\mu$ A /30min and AC ripple of 21$\mu$ A are achieved.

A spherical scattering electrical-field probe(SSEP) with noncontact, 3D isotropy and approximate point probing characteristics has been proposed for high-precision measurement of micro and small structures with large aspect ratio. Development of signal processing circuits for detection of weak cpacitantive signal on sub-picofarad level is the key to realize nanometer resolution. In this paper, a set of signal processing circuits based on operational capacitance measurement principle is proposed, and characteristics of the circuits are theorically analyzed and optimized. Experimental results indicates that resolution of 1 nm and nonlinearity of6 nm are achieved with the proposed signal processing circuits for a SSEP with $\phi$ 2.5 mm probing ball.

A low ripple switching power supply with 0-12 V voltage and 35 A maximum current outputs is developed for the application of high-precision thermoelectric circulating water cooling. In order to suppress the voltage ripple in the output caused by voltage and current spikes generated when the switching mode of full-bridge converter changes, which is further resulted from parasitic capacitance and inductance of MOSFET circuit and rectifier diode circuit in the power supply, resonance analysis and optimization design is carried out. Equivalent models of MOSFET circuit and rectifier diode circuit are established, and absorption circuits are designed to absorb the voltage and current spikes, thus to effectively suppress the voltage ripple in the output of the switching power supply. Experimental results show that the output voltage ripple is reduced from 190 mV to 88 mV after optimization of key parameter.

A circulating cooling water machine using agile bidirectional cooling and heating power control method is developed to produce circulating cooling water of high temperature stability and good dynamic performance. Cooling module based on thermoelectric cooling and multilayer compact structure is proposed to achieve cooling power output resolution at sub-watt level and quick response. Heating module based on a compact solenoid-in-tube structure is proposed to achieve heating power output with sub-watt level resolution and quick response. Experiments indicate that temperature stability of ± 3 mK, regulating resolution of 5 mK and regulating time of 128 s corresponding to 1 K step of circulating cooling water temperature are achieved with the developed machine. Thus, the developed machine can satisfy the challenging requirements of precision manufacturing.

Thermal pollution is one of the most urgent issues in the fields of ultra-precision measurement and manufacturing, which presents the demand of producing ultra-precision circulating cooling water (CCW) with the temperature stability up to millikelvin level and response time at hundred-second level. In this paper, an ultra-precision CCW producing method based on model identification and fuzzy-PID control is proposed and illustrated. A structure of circulating water loop with ultra-precision temperature control is proposed. A cooling module using of thermoelectric cooling device arrays as refrigerator and a heating module using electrical heating-tubes as heater are employed. A control algorithm based on fuzzy-PID is designed, and a variety of model identification experiments has been carried out to extract key parameters of the modules. Experimental results show that a temperature stability up to ±3mK is achieved, the temperature control resolution is better than 5mK, and the adjusting time of 1K step is 128s, satisfying the urgent need of ultra-precision measurement and manufacturing.

In order to solve the difficulty of precision measurement of small hole diameters with large depth-to-diameter ratios, a new measurement method based on spherical scattering electrical-field probing (SSEP) was developed. A spherical scattering electrical field with identical sensing characteristics in arbitrary spatial directions was formed to convert the micro gap between the probing-ball and the part being measured into an electrical signal. 3D non-contact probing, nanometer resolution, and approximate point probing&mdash, which are key properties for high measurement precision and large measurable depth-to-diameter ratios&mdash, were achieved. A specially designed hole diameter measuring machine (HDMM) was developed, and key techniques, including laser interferometry for macro displacement measurement of the probe, multi-degree-of-freedom adjustment of hole attitude, and measurement process planning, are described. Experiments were carried out using the HDMM and a probing sensor with a ϕ3-mm probing ball and a 150-mm-long stylus to verify the performance of the probing sensor and the measuring machine. The experimental results indicate that the resolution of the probing sensor was as small as 1 nm, and the expanded uncertainty of measurement result was 0.2 &mu, m (k = 2) when a ϕ20-mm ring gauge standard was measured.

In order to solve the problem of stylus vibration of the spherical capacitive probe with ultra-large aspect ratio, modal analysis of the stylus is done and optimal design of stylus structure is carried out. The Euler–Bernoulli Beam model is introduced to build the dynamic equation of lateral vibration of the stylus. Based on results of modal analysis and simulation, the first order natural frequency of the stylus is optimized to near 100 Hz, and the resolution of the probing sensor is improved from 20 nm to 4 nm with adoption of damping material.

In order to solve the problem of thermal drift and further improve the performance for sensors with extreme demand for precision, based on analysis of shortcomings of existing compensation methods and characteristics of thermal drift, a novel active suppression technology against thermal drift is proposed. Considering the change of properties of reference elements in sensors caused by temperature variation is the most major factor that introduces thermal drift error, a special thermal structure is designed to provide a small environmental chamber with sub-structure design of high performance heat isolation, heat conduction and homogenization of temperature, and the temperature in the environmental chamber is controlled with high precision based on bilateral temperature adjusting with thermo electronic cooler (TEC) devices, and a compound control algorithm of Bang-Bang and anti-windup PID. Experimental results with an ultra-precision spherical capacitive sensor show thermal drift error is significantly eliminated and the precision of the sensor can reach the level of several resolutions.