Real-Time Iterative Compensation Framework for Precision Mechatronic Motion Control Systems

With regard to precision/ultra-precision motion systems,it is important to achieve excellent tracking performance for various trajectory tracking tasks even under uncertain external disturbances.In this paper,to overcome the limitation of robustness to trajectory variations and external disturbances in offline feedforward compensation strategies such as iterative learning control(ILC),a novel real-time iterative compensation(RIC)control framework is proposed for precision motion systems without changing the inner closed-loop controller.Specifically,the RIC method can be divided into two parts,i.e.,accurate model prediction and real-time iterative compensation.An accurate prediction model considering lumped disturbances is firstly established to predict tracking errors at future sampling times.In light of predicted errors,a feedforward compensation term is developed to modify the following reference trajectory by real-time iterative calculation.Both the prediction and compen-sation processes are finished in a real-time motion control sampling period.The stability and convergence of the entire control system after real-time iterative compensation is analyzed for different conditions.Various simulation results consistently demonstrate that the proposed RIC framework possesses satisfactory dynamic regulation capability,which contributes to high tracking accuracy comparable to ILC or even better and strong robustness.

Investigation of a Pressure Sensor with Temperature Compensation Using Two Concentric Wheatstone-Bridge Circuits

This study presents a silicon-based pressure sensor with temperature compensation. The eight piezoresistors were designed on the polycrystalline silicon membrane and constructed by two concentric Wheatstone-bridge circuits to perform two sets of sensors. The sensor in the central circuit measures the membrane deflection caused by the combined effects of pressure and temperature, while the outer one measures only the deflection caused by the working temperature. From this arrangement, it is reliable and accurate to measure the pressure by comparing the output signals from the two concentric Wheatstone-bridge circuits. The optimal positions of the eight piezoresistors were simulated by simulation software ANSYS. The investigated pressure sensor was fabricated by the micro electro-mechanical systems (MEMS) techniques. The measuring performance and an indication of the conventional single Wheatstone-bridge pressure sensor is easily affected under variation of different working temperature and causes a maximum absolute error up to 45.5%, while the double Wheatstone-bridge pressure sensor is able to compensate the error, and reduces it down to 1.13%. The results in this paper demonstrate an effective temperature compensation performance, and have a great performance and stability in the pressure measuring system as well.

Temperature Compensation Algorithm for Hydraulic System Pressure Control

In this paper the control mechanism of solenoid valve is analyzed,which shows the solenoid valve control is actually the control of coil current.The response characteristic of coil current is related to coil inductance and resistance.The coil resistance is influenced greatly by the ambient temperature and the self-heating of coil,which affects the control precision of coil current.First,considering the heat dissipation mode of coil,the coil temperature model is established from the perspective of heat conduction,and a temperature compensation algorithm for hydraulic system pressure control is put forward.Then the hardware-in-the-loop testbed is set up by using the dSPACE platform,carrying out wheel cylinder pressurization tests with inlet valve fully opened at-40℃ and 20℃,and testing the actual pressure of wheel cylinder with the target pressures at-40℃ and 6 000 kPa/s(pressurization rate).The results show that the pressure control temperature compensation algorithm proposed in this paper accurately corrects the influence of resistance temperature drift on the response accuracy of wheel cylinder pressure.After the correction,the pressure difference is less than 500 kPa,which can meet the control accuracy requirements of solenoid valve,enriching the linear control characteristic of solenoid valve.

Comparison of delay compensation methods for real-time hybrid simulation using frequency-domain evaluation index

The delay compensation method plays an essential role in maintaining the stability and achieving accurate real-time hybrid simulation results. The effectiveness of various compensation methods in different test scenarios, however, needs to be quantitatively evaluated. In this study, four compensation methods （i.e., the polynomial extrapolation, the linear acceleration extrapolation, the inverse compensation and the adaptive inverse compensation） are selected and compared experimentally using a frequency evaluation index （FEI） method. The effectiveness of the FEI method is first verified through comparison with the discrete transfer fimction approach for compensation methods assuming constant delay. Incomparable advantage is further demonstrated for the FEI method when applied to adaptive compensation methods, where the discrete transfer function approach is difficult to implement. Both numerical simulation and laboratory tests with predefined displacements are conducted using sinusoidal signals and random signals as inputs. Findings from numerical simulation and experimental results demonstrate that the FEI method is an efficient and effective approach to compare the performance of different compensation methods, especially for those requiring adaptation of compensation parameters.

The dynamic compensation temperature in a kinetic spin-5/2 Ising model on a hexagonal lattice

We present a study of the dynamic behavior of a two-sublattice spin-5/2 Ising model with bilinear and crystal-field interactions in the presence of a time-dependent oscillating external magnetic field on alternating layers of a hexagonal lattice by using the Glauber-type stochastic dynamics.The lattice is formed by alternate layers of spins σ=5/2 and S=5/2.We employ the Glauber transition rates to construct the mean-field dynamic equations.First,we investigate the time variations of the average sublattice magnetizations to find the phases in the system and then the thermal behavior of the dynamic sublattice magnetizations to characterize the nature（first-or second-order） of the phase transitions and to obtain the dynamic phase transition（DPT） points.We also study the thermal behavior of the dynamic total magnetization to find the dynamic compensation temperature and to determine the type of the dynamic compensation behavior.We present the dynamic phase diagrams,including the dynamic compensation temperatures,in nine different planes.The phase diagrams contain seven different fundamental phases,thirteen different mixed phases,in which the binary and ternary combination of fundamental phases and the compensation temperature or the L-type behavior strongly depend on the interaction parameters.

Temperature compensation method for low cost three-axis MEMS digital angular rate gyroscopes

In recent years,a large number of small volume,low cost micro electro mechanical systems（MEMS）digital three-axis angular rate gyroscopes have been developed and widely used in civil and military fields.However,these kinds of gyroscopes have poor performances in initial zero-bias,temperature drift,In-Run bias stability,bias repeatability,etc.,their output errors need to be compensated before being used.Based on a lot of experiments,the temperature drift and the initial zero-bias are the major error sources in the MEMS gyroscopes output data.Due to the poor repeatability of temperature drift,the temperature compensation coefficients need to be recalculated every time before using.In order to recalculate parameters of the temperature compensation model quickly,a 1st-order polynomial model of temperature is established,then a forgetting factor recursive least squares estimator will be adopted to identify the model parameters in real time.Static and dynamic experimental data shows that this method removed/compensated the temperature drift and initial zero-bias from the output of the gyroscopes effectively.

Development of Drone Cargo Bay with Real-Time Temperature Control

In order to deliver medical products (medicines, vaccines, blood packs, etc.) in time for needed areas, a method of transporting goods using drones is being studied. However, temperature-sensitive medical products may decay due to outside temperature changes. The time required to transport over the distance may vary a lot as well. As a result, the likelihood of the goods deteriorating is very high. There is a need for a study on cargo bay to prevent this and to protect the medical goods. In this paper, in order to protect the temperature sensitive medical goods, the inside cargo bay is equipped with the cooling fan device and the electric heating elements. These elements can be monitored and controlled according to the user’s discretion. By using the web server built inside the cloud server, the temperature can be controlled in real-time from anywhere without the limitation of distance. We built the proposed device, and installed it on the drone cargo bay. The test results show that the cargo bay can be temperature-controlled, and the setting can be maintained over a great distance. The user can watch the temperature variations during the transport and ascertain the goodness of the medical supply with the data. It is expected that such development can greatly enhance the utility of the drone operations, especially for the medical supply transport applications.

Real-time quantitative optical method to study temperature dependence of crack propagation process in colloidal photonic crystal film

A real-time quantitative optical method to characterize crack propagation in colloidal photonic crystal film（CPCF）is developed based on particle deformation models and previous real-time crack observations. The crack propagation process and temperature dependence of the crack propagation rate in CPCF are investigated. By this method, the crack propagation rate is found to slow down gradually to zero when cracks become more numerous and dense. Meanwhile, with the temperature increasing, the crack propagation rate constant decreases. The negative temperature dependence of the crack propagation rate is due to the increase of van der Waals attraction, which finally results in the decrease of resultant force. The findings provide new insight into the crack propagation process in CPCF.

Temperature Compensation for Double Fiber Bragg Grating Sensors

一种新奇双纤维布拉格栅栏(FBG ) 紧张传感器配置被介绍。温度赔偿方法基于两倍 FBG 在一个菱形框架上系在。Throughthe 理论分析，在在传感器上使用的布拉格波长和紧张的相对移动之间的关系被获得，并且紧张灵敏系数的分析表示也被给。实验结果显示出那：在 0 ～的紧张范围 0.8 公里，在布拉格波长和应用紧张的相对移动之间的关系是线性的，并且在 60 ℃是的 -25 ℃～的范围的两倍 FBG 波长的分散 0 ～ 0。002 nm。排水量传感器配置的紧张敏感是 0。171 nm/ με，并且将近两次比单个 FBGsensor 的。

Symmetric Temperature Compensation for Photoelectric Coupling Current Transducer

The temperature characteristic of sensor probe at high voltage side is analyzed by using a photoelectric coupling current transducer. The principle of symmetric temperature compensation and the main idea of software design are proposed. The method increases measuring precision and has fairly great practicability.

Reliability Design and Simulation of a Surface-Mount Temperature Compensation Crystal Oscillator

This paper introduces the structure and principle of a surface-mount high-precision temperature compensation crystal oscillator,and specifically describes the reliability design of a quartz-crystal resonator used inside the surface-mount temperature compensation crystal oscillator,the reliability design of surface-mount ceramic base and the reliability design of hybrid micro-assembly.Finally,the thermal and mechanical simulation results and the experimental verification of this surface-mount temperature compensation crystal oscillator are provided,which prove that this crystal oscillator has high reliability.

Novel Fiber Optic Temperature Sensor with Full Compensation Based on Optical Absorption

A novel system configuration of fiber optic sensor based on optical abso rption is proposed. Several compensation measures are discussed. A simulated exp eriment is designed and the output curve of system is given. The experiment al result shows that these compensation measures are effective on dynamic distu rbances which are caused by background light and optical fiber bend. In addition , the drifts in the light source intensity, fiber losses, and photodetector effi ciency are also compensated.

A New CMOS Current Reference with High Order Temperature Compensation

A new high order CMOS temperature compensated current reference is proposed in this paper, which is accomplished by two first order temperature compensation current references. The novel circuit exploits the temperature characteristics of integrated-circuit resistors and gate-source voltage of MOS transistors working in weak inversion. The proposed circuit, designed with a 0.6 Izm standard CMOS technology, gives a good temperature coefficient of 31ppm/℃ [-50-100℃] at a 1.8V supply, and also achieves line regulation of 0.01%/V and-120dB PSR at 1 MHz. Comparing with other presented work, the proposed circuit shows better temperature coefficient and Line regulation.

Trimmable bandgap reference circuit with exponential curvature compensation

This paper proposes an improved exponential curvature-compensated bandgap reference circuit to exploit the exponential relationship between the current gainβof the bipolar junction transistor(BJT)and the temperature as well as reduce the influence of resistance-temperature dependency.Considering the degraded circuit performance caused by the process deviation,the trimmable module of the temperature coefficient(TC)is introduced to improve the circuit stability.The circuit has the advantages of simple structure,high linear stability,high TC accuracy,and trimmable TC.It consumes an area of 0.09 mm^(2)when fabricated by using the 0.25-μm complementary metal-oxide-semiconductor(CMOS)process.The proposed circuit achieves the simulated power supply rejection(PSR)of about-78.7 dB@1 kHz,the measured TC of~4.7 ppm/℃over a wide temperature range from-55℃to 125℃with the 2.5-V single-supply voltage,and the tested line regulation of 0.10 mV/V.Such a high-performance bandgap reference circuit can be widely applied in high-precision and high-reliability electronic systems.

Research on frequency-temperature compensated sapphire-SrTiO_3 loaded cavity for hydrogen maser

To obtain frequency-temperature compensation in a sapphire loaded cavity for hydrogen maser, a dielectric named SrTiO3 is employed whose temperature coefficient of permittivity is opposite to that of sapphire. Based on theoretical analysis and computer simulation, a TE011 mode of a sapphire loaded cavity associated with two small rings of SrTiO3 with different thickness is solved, and the useful parameters that influence the temperature coefficient of cavity are calculated. Finally an experiment is brought forward and its results are very close to the computing results. When the thickness of SiTiO3 dielectric is 7 mm and the diameter is 17 mm in configuration b, the temperature coefficient of cavity is decreased from -58.8 kHz/K to -8.2 kHz/K and the quality factor is 40248.

TWO NEW TYPES OF MICROWAVE RADIOMETER: A COMPUTER GAIN COMPENSATIVE DESIGN AND A REAL-TIME CALIBRATED DESIGN

Long term stability is the main factor that influences the minimum detectable signal of microwave radiometers. Two new types of microwave radiometer were studied: a computer gain compensative microwave radiometer and a real-time calibrated microwave radiometer. The long term stability of both designs was optimal because they were insensitive to system gain fluctuations. The continuous calibrated microwave radiometer was also insensitive to system noise fluctuations. The minimum detectable signals were 0.13 and 0.19K respectively under an integration time of 0.6s.

Gene Expression and Activities of SOD in Cucumber Seedlings Were Related with Concentrations of Mn^(2+),Cu^(2+),or Zn^(2+) Under Low Temperature Stress

Effects of increasing Mn^2＋, Cu^2＋, or Zn^2＋ on SOD expressions were studied in cucumber seedlings under low temperature stress. Both gene expressions and activities of Cu/Zn-SOD and Mn-SOD in cucumber seedling leaves were induced by increasing Mn^2＋, Cu^2＋, or Zn^2＋ under low temperature stress, especially 48 h afterwards. The activities of Cu/Zn-SOD and Mn-SOD at 0 and 48 h after treatment were in accordance with their gene expression levels, which implied that the transcriptional regulation plays key roles in regulating their activities at the early stage of low temperature stress. Gene expressions of Cu/Zn-SOD and Mn-SOD declined at 96 h, but Cu/Zn-SOD and Mn-SOD activities still remain high, which suggested that Cu/Zn-SOD and Mn-SOD activities might be regulated by other factors after transcription at the later stage of low temperature stress. Therefore, we concluded that the increasing Mn^2＋, Cu^2＋, or Zn^2＋ could increase the capacity of scavenging ROS in cucumber seedlings under low temperature stress by inducing gene expressions of Cu/ Zn-SOD and Mn-SOD, elevating activities of Cu/Zn-SOD, Mn-SOD, or regulating other factors after transcription.

Periodic Error Compensation for Quartz MEMS Gyroscope Drift of INS

In order to improve the navigation accuracy of an inertial navigation system （INS）, composed of quartz gyroscopes, the existing real-time compensation methods for periodic errors in quartz gyroscope drift and the periodic error term relationship between sampled original data and smoothed data are reviewed. On the base of the results, a new compensation method called using former period characteristics to compensate latter smoothness data （UFCL for short） method is proposed considering the INS working characteristics. This new method uses the original data without smoothing to work out an error conversion formula at the INS initial alignment time and then compensate the smoothed data errors by way of the formula at the navigation time. Both theoretical analysis and experimental results demonstrate that this method is able to cut down on computational time and raise the accuracy which makes it a better real-time compensation approach for periodic error terms of quartz micro electronic mechanical system （MEMS） gyroscope＇s zero drift.

HIGH TEMPERATURE DISPLACEMENT SENSOR

A high temperature displacement sensor based on the principle of eddy-current is investigated. A new temperature compensation technique by using eddy-current effect is presented to satisfy the special requirement at high temperature up to 550℃. The experiment shows that the temperature compensation technique leads to good temperature stability for the sensors. The variation of the sensitivity as well as the temperature drift of the sensor with temperature compensation technique is only about 7.4% and 90-350 mV at 550 ℃ compared with that at room temperature, and that of the sensor without temperature compensation technique is about 31.2% and 2-3 V at 550 ℃ compared with that at room temperature. A new dynamic calibration method for the eddy-current displacement sensor is presented, which is very easy to be realized especially in high frequency and at high temperatures. The high temperature displacement sensors developed are successfully used at temperature up to 550 ℃ in a magnetic bearing system for more than 100 h.

Temperature Stress at Grain Filling Stage Mediates Expression of Three Isoform Genes Encoding Starch Branching Enzymes in Rice Endosperm

An early-maturity indica rice variety Zhefu 49, whose grain quality and starch structure are sensitive to environmental temperature, was subjected to different temperatures （32℃ for high temperature and 22℃ for optimum temperature） at the grain filling stage in plant growth chambers, and the different expressions of three isoform genes （SBEI, SBEIII and SBE/V） encoding starch branching enzyme （SBE） in the endosperms were studied by the real-time fluorescence quantitative PCR （FQ-PCR） method. Effects of high temperature on the SBE expression in developing rice endosperrns were isoform-dependent. High temperature significantly down-regulated the expressions of SBEI and SBEIII, while up-regulated the expression of SBEIV. Compared with SBEIV and SBEIII, the expression of SBEI gene in Zhefu 49 rice endosperms was more sensitive to temperature variation at the grain filling stage. This study indicates that changes in weather/climate conditions especially temperature stress influence rice grain formation and its quality as evidenced by isoform expression.