Abstract:Starting from the tactile sensing performance of human skin, the progress and key technologies of tactile sensors for e-skin (electronic skin) akin to human skin by multidisciplinary fields are comprehensively reviewed. The sensing principle, new materials and structures, advanced design and making methods, sensing characteristics and performance of tactile sensors are analyzed. The recent domestic and foreign research advances of electronic skin tactile sensor array in flexibility, elasticity, spatial resolution, sensitivity, fast response, transparency, lightweight, multifunction and other aspects are summarized. It is difficult to achieve the tactile sensors for e-skin with high stretchable and flexible, less complex production process for high sensitivity e-skin, strong extensibility and low cost. The tactile sensors for e-skin can be widely used in robotics, medical health, aeronautics and space military, intelligent manufacturing, automotive security and other fields. The development of tactile sensors for e-skin toward the direction of high stretchable and flexible, high sensitivity in wide range, multifunction, self-healing and self-cleaning, self-powered and transparent, has been pointed out.

Abstract:A double-layer loop deployable antenna mechanism driven by elastic hinge was proposed to solve the design problem of over-large deployable antenna with high stiffness and light weight. The static analysis model of the antenna structure was established to get the interactional relationship between the bars and cables in this structure and the value range of the pre-tightening force in diagonal cables. The first six order vibration frequency and their relevant modal shapes of these two kinds of the antenna structures were assessed by dynamic analysis. In addition, it was found that the stiffness of the antenna structure with cables is 1.2 times of that of the cable-free structure. The effects of structural parameters on vibration frequency were pointed out, as well as the effective strategies to improve the vibration frequency of the antenna structure based on the sensitivity analysis of factors. It is found that the vibration frequency of the antenna structure can be improved by increasing the cross-sectional area of the transverse bar and the stay cable and reducing the cross-sectional area of the longitudinal bar.

Abstract:Respect to the issue of serving humanoid robots following human， walking pattern generation based on human walking capturing is studied, and experimental study of following walking between a biped robot and human is conducted. Considering the motion capability limitation of the robot, human walking patterns obtained online by PS three-dimensional capture system are matched to the robot in kinematics aspect to generate robots’ walking patterns and to build a library for them. Similarities between the robot and human are defined by parameters in both the Cartesian space and the joint space. The similarity based method of choosing walking patterns online and the “joint angle distance” based method of pattern transition are proposed to solve the problem of following walking with varying velocity. Finally, the experiments of biped robot following different people are conducted, in which stable walking is achieved. The following distance error is in the range of ±52 mm during the following process and the position error is no more than ±10 mm after the following process ended.

Abstract:To study the anti-resonance of motorized spindle influenced by variations of structural parameters, the structure of one motorized spindle is parameterized firstly using ANSYS and then the modal analysis is carried out. With the ISIGHT platform integrated into ANSYS, several significant geometric and material parameters of the motorized spindle system are selected out as design variables to obtain sufficient samples by Optimal Latin Hypercube method. To fit the function between the low-order natural frequency and the random variables, the BP neural networks are constructed and the reliability limit state equation of the motorized spindle frequency is obtained. Subsequently, the frequency reliability and sensitivity of the motorized spindle, calculated with updating first order second moment method (AFOSM), are verified by Monte-Carlo method. The results show that the density, elastic modulus and the total length of the motorized spindle significantly affect the frequency reliability, in terms of the mean and standard deviation. Meanwhile, the reliability limit state equation constructed by the BP neural networks is relatively rational. The AFOSM to analyze the frequency reliability-based sensitivity is comparatively precise and with higher efficiency than Monte-Carlo method.

Abstract:In view of the problem that flexible displacement will occur for end-effectors of parallel manipulators when operating at a high speed, taking the 3RRR parallel manipulator as the object, the trajectory tracking composite controller based on the integral manifold and high-gain observer is proposed for flexible parallel manipulators. Based on the stiffness matrix, the small variable is introduced to decomposite the rigid-flexible coupling dynamic model of the parallel manipulator into slow subsystem and fast subsystem. For the slow subsystem, the backstepping control is applied for rigid motion tracking of the end-effector. To avoid the influence of the links’ flexible displacement comprised of deformation and vibration on the end-effector’s motion trajectory, the corrective torque is deduced, and the compensation for the flexible displacement is realized. For the fast subsystem, the sliding mode control is utilized to suppress the vibration. At the same time, the high gain observer is designed to avoid the measurement of curvature rate of the flexible links. Also, the stability of the overall system with the proposed method is proven with the Lyapunov stability theorem and the upper bound of the small variable is obtained. At last, the proposed composite controller together with the singular perturbation control and the rigid model based on backstepping control are simulated, and the vibration suppression and tracking accuracy performances are compared to validate the proposed control scheme.

Abstract:To calculate the temperature field of bump foil gas bearing, and to analyze its thermal characteristics, considering outer cooling condition and specific foil structure, the equivalent heat convective coefficient on the inner side of top foil is derived, and the heat conductive and convective models of bearing sleeve and rotor are established respectively. Non-isothermal Reynolds equation, energy transfer equation of gas film and foil deflection equation are solved. The influences of bearing load, out cooling condition, bearing speed, etc. on bearing temperature are finally obtained, and the static and dynamic performance of the bearing is calculated. The results indicate that the bearing temperature is very sensitive to the bearing speed, and the cooling efficiency of the out cooling flow becomes weak with the increase of the cooling mass flow rate. The smaller nominal clearance plays a more important role in influencing the bearing temperature than the larger one. In addition, with the temperature effects considered, the bearing will achieve higher load capacity, larger dynamic stiffness and damping coefficients.

Abstract:For olfactory sense and gas mixtures identification of humanoid robots, an artificial lung & olfactory sense system (HAL&OS-I) and its identification method through active breathing are proposed and researched. The integrated hardware of the system mainly consists of micro vacuum pump, five gas sensors for alcohol/hydrogen sulfide/ammonia/smoke/methane separately, and the single chip microcomputer along with the circuit boards for signal sampling and processing. Gas identification experiments of five pure gases and four gas mixtures were conducted by using K-mean cluster analysis method, genetic algorithm combined with neural network (GA+BP), cascade neural network (GA+3BP) separately. The experimental results show that the identification rate of five pure gases by the GA+BP algorithm is above 90%, but the identification rate is relatively low when the gas mixtures are included. Gas identification rate of all gases by the GA+3BP algorithm is more than 90% except the smog and hydrogen sulfide mixture gas of which the identification rate is 70%. It is revealed that the GA+nBP algorithm has higher identification rates for multiple pure and gas mixtures.

Abstract:To avoid the time-consuming match of multiple feature points and the difficulty in getting the full pictures of Long Shaft Part(LSP) in the process of measuring its 3D pose using non-orthogonal binocular stereovision, a method for measuring 3D pose of assembly end of LSP based on orthogonal binocular stereovision is presented. The pictures of assembly end of LSP are taken individually at the same time by two cameras whose optical axes are perpendicular to each other and processed by method of sub-pixel respectively, and then the position and posture of assembly end of LSP in the image coordinate systems of two cameras can be obtained. The 3D pose of assembly end of LSP can be acquired from the information fusion of position and posture of LSP in two image coordinate systems according to the model of orthogonal binocular stereovision. Experimental result shows that the 3D pose of assembly end of LSP can be measured rapidly and precisely by orthogonal binocular stereovision consisting of two CMOS cameras. Since only one feature point needs to be matched in this method with simplicity and low calculation cost, it can be applied to the rapid assembly of precise LSP with robots guided by machine vision.

Abstract:To study the impact of mechanical structure on the torque loading performance of a friction based electro-hydraulic load simulator, the loading principle of the proposed load simulator is described, and a prototype of one-way load simulator is built. The linear mathematical model of the proposed load simulator is established, and a PID plus feed-forward controller is designed to improve precision of the torque tracking control without any extra torque compensation. The impacts of the spring stiffness, the frictional performance of the friction discs, etc on the torque loading performance are studied experimentally. Then, the experimental studies are focused on the small amplitude torque loading performance of the proposed load simulator with severe disturbance of the steering engine. The experimental results show that the friction based torque loading method has no structural extra torque, and can achieve high torque loading performance. Besides, to further improve the torque loading performance, the stiffness of the spring should be optimized, the friction disc material with excellent friction properties is needed and the high performance controller should be designed.

Abstract:To know the vibration characteristics of thin cylindrical shell with constrained layer damping, Hamilton principle with Rayleigh-Ritz method is used to solve the dynamic equation. Based on this, natural frequencies and loss factors of free vibration are analyzed. Modal Superposition method is used to calculate the formulas of frequency response on any points in the shell. In addition, based on frequency response, power dissipation coefficient is proposed. The power dissipation coefficient and loss factors are used respectively as constrained layer damping effect evaluation criteria and to analyze the influence of constrained layer damping structure parameters on the damping effect. Numerical results show that the constrained layer damping can effectively inhibit vibration transmission of thin cylindrical shell. The power dissipation coefficient can be used as damping effect evaluation criteria in the specified frequency band. The coefficient of viscoelastic damping material, elastic modulus of constrained layer, thickness of constrained layer and thickness of damping layer can affect the damping effect.

Abstract:An equivalent radiation-concentrating method was developed for calculating the radiative flux of targets into sensor pixels array in an infrared (IR) detecting system. This method contains division of the imaging process: the formation and transfer of the radiation field of targets and the concentration of it in the IR optical system. In the first process, the Monte Carlo (MC) method is adopted for simulating the formation of the equivalent radiation and for simulating the transfer of it to the IR system. Then in the later process, the optical relations are employed for locating the image and for calculating the light intensity transformation. The developed method was applied for calculating the infrared image of the SDM airplane at different detecting azimuth, and the results were compared in terms of efficiency with those from the reverse Monte Carlo method that traced rays from the sensor pixels array. It is shown that for one single detecting azimuth, the developed method is closed to the reverse Monte Carlo method with respect to efficiency; for multiple detecting azimuths, compared to the reverse Monte Carlo method that coupled the generation and concentration of the effective radiation of targets, the developed method results in computing cost savings and so is more suitable in engineering applications.

Abstract:For energy conversion with high efficiency and low carbon emission, Oxy-Coal Combustion Steam System for power generation with near-zero emissions was proposed. The Ignition Temperature of Yimin demineralized coal and Zhundong demineralized coal were studied in a one-dimensional drop tube furnace at different oxygen concentration and steam concentration. The impact of pressure on the ignition temperature was investigated by High Pressure Steam TGA. The results show that the oxygen volume concentration is very important for the ignition temperature of demineralized coal. With the increasing of oxygen concentration, the ignition temperature is gradually reduced. With the increasing of the concentration of steam, the ignition temperature is gradually raised. When the steam volume concentration, range from 10% to 50%, increases 10%, the ignition temperature increases about 30 ℃. When the pressure is less than 1.0 MPa, with the increasing of pressure, the ignition temperature of Zhundong demineralized coal decreases, when the pressure is in the range of 1.0-2.0 MPa, then no obvious change for the ignition temperature, but when the pressure is greater than 2.0 MPa, the ignition temperature increases.

Abstract:To improving the atomization characteristics of dual impinging jets, based on the impinging jets platform established by ourselves, the effects of jet velocity, impingement angle, nozzle diameter and liquid viscosity on the atomization characteristics were studied by CCD Photography technology. The experimental results indicate that with the increase of Weber number and impingement angle, the spray angle is increased, droplet SMD is decreased and the droplet distribution is more uniform. When the nozzle diameter is small, the thickness of liquid sheet is small, the liquid sheet is unstable and the spray angle is small. The nozzle diameter has little influence on SMD. Besides, the larger the liquid viscosity, the more unstable of the liquid, the larger the liquid size, the smaller the spray angle and the larger the droplet SMD. When the Weber number is small, the difference is obvious and when the Weber number is large, the difference is smaller. Also, in the study of 40% concentration of glycerol solution atomization characteristics, the phenomenon of liquid sheet flip was observed, and multiple consecutive perpendicular liquid sheets could appear down from the impact point. In conclusion, increasing the jet velocity and impinging angle and decreasing the liquid viscosity can improve the atomization characteristics.

Abstract:The method of computational fluid dynamics (CFD) containing reactive mass transfer is adopted to simulate the process of carbon dioxide capture from flue gases with MEA in structured packing. The simulation of complex flows with second order reaction of CO₂ with MEA is built in representative elementary units (REU) of structured packed column. Various operating conditions including ratio of gas inlet flow to liquid inlet flow, CO₂ inlet mass fraction, MEA mole fraction and pressure on CO₂ capture process are examined. The absorption efficiency increases with the addition of MEA concentration and operating pressure, but decreases with CO₂ concentration and gas-liquid flow ratio. The influences of different factors on the absorption are ordered as MEA mole fraction, CO₂ mass fraction, ratio of gas inlet flow to liquid inlet flow and pressure. The CFD results of CO₂ absorption rate at different operating parameters are consistent with the reported ones, and the optimal parameters are got.

Abstract:To improve the performance of FSAE (Formula SAE) electric racing car in the endurance race, a whole regenerative braking system was designed accordingly. Firstly, the simulation software ADVISOR was redeveloped and the vehicle model, wheel model, driving control model and battery model were modified. Secondly, to ensure the system stability and reduce the influences of controller and sensor accuracy, a rear-wheel parallel control strategy of regenerative braking system was proposed and the simulation of this control strategy was complimented in ADVISOR. Thirdly, the regenerative braking system controller was designed and racing car trials were carried out. The results showed that in the simulations and trials, the regenerating efficiencies were 20.89% and 19.07% respectively. The regenerative braking system with the rear-wheel parallel control strategy could improve the performance of FSAE racing car effectively.

Abstract:For analyzing the influences of different gravities of the Earth and the Moon on driver of lunar roving vehicle (LRV), the handling dynamic functions were deduced. Based on RBF neutral networks and indirect inverse model training methods, the inverse handling system of LRV, whose inputs were the moving traces and outputs were the handling angles of the driver, was obtained. Two types of indirect comparisons were used for the inverse system, including repeating the moving traces on the Moon under the earth’s gravity and repeating the moving traces on the Earth under the lunar gravity. The sine and ramp-pulse were used as the handling functions, and the moving traces on the Moon or the Earth could be solved by the handling dynamic system. Then, the handling angles could be obtained by the inverse system when repeating same traces under different gravities. The results show that the driver needs bigger steering angle, more rapid steering speed, and more frequent steering shift under the lunar gravity. Morever, it is much more difficult to repeat the same trace under the lunar gravity than under the earth’s gravity. It illustrats that the LRV has the worse handling performances on the Moon.

Abstract:The dual-mode electro-mechanical transmission system for heavy duty vehicles is a power split hybrid system, which transmits engine power through mechanical and electrical power flow. Aiming at the precision of mechanical and electrical power distribution and the responding speed of electrical power supply, the electric power coordinated control strategy is proposed. Making use of quick response and accuracy control of motors, the strategy can realize the precise power distribution of engine and battery and supply steady electric power by coordinating the working state of generator and motor. The simulation results indicate that the actual power of battery will follow its target value in real time and the electric power will be supplied rapidly when it is needed. The electric power coordinated control strategy can achieve the precise distribution of mechanical and electrical power and the high responding speed of electrical power supply in complex dynamic control system.

Abstract:Based on the Carman-Kozeny-Blake model and the contracting-expanding channel model, this study developed a new resistance model for predicting power law fluid flow through granular porous medium with homogeneous spherical particles. For the rheological properties of power-law fluid, by employing the average hydraulic radius theory, a modified Ergun type equation was expressed as a function of tortuosity, porosity, ratio of pore diameter to throat diameter, diameter of particles, and fluid rheological index. Every parameter such as A and B in the proposed model had clear physical meaning. The validity of the present model was evaluated by comparing the predicted friction factor to the published theoretical models and the experimental data correlations, the analysis results showed that the new model predictions were in good agreement with the existing documents data in a certain regime. At last, to further understand the flow resistance characteristic, the correlations of critical Reynolds number, the modified permeability and the inertia coefficient for power law fluid were also expressed.

Abstract:To evaluate the fault correlation of machining center system components, by using the related fault mechanism analysis combining graph theory, a method of transfer directed graph of system components fault is built up, the correlation evaluation of system components is converted to the calculation of complex network node importance, and by the adjacency matrix and its transpose transform combining PageRank algorithm, the CNC machining center fault correlation method is obtained. The calculation results show that the size of fault correlation and the relation of component fault correlation is proportional, and the fault correlation of the fault correlation component is greater than those components with no fault correlation. If the influenced degree of a component is larger than its influencing degree, it is the fault appearance component, on the contrary, it is the fault source component. This helps to the fault diagnosis and maintenance.

Abstract:To improve the dynamic performance of a radial driving shaft employed on an aero engine,a theoretical analysis based on FEM is conducted. Dynamic model and equation is constructed consistent with the actual structure and practical operating condition. The influences of gyroscopic moment,supporting stiffness and location of the intermediate fulcrum on shaft critical speed are discussed. The method to determine the intermediate supporting location is suggested,which is believed to be valuable in practical design of radial driving shaft. Analysis results indicate that the gyroscopic moment has minimum impact on the natural frequency,less than 0.5%. When the intermediate fulcrum is located at the point of the ‘ Natural Mode' of second curved modal shape with no intermediate fulcrum,the highest critical speed and design margin of supporting stiffness could be achieved. The experimental results prove the correct of the theoretical analysis.

Abstract:An analysis model about the deposition characteristics of oil droplet on the housing in a bearing chamber is proposed to provide the basic conditions of oil film flow investigation. Firstly，the transition criteria for droplet/ housing interaction is determined，and considering the temperature variation of droplet，the deposition mass and momentum of oil droplet on housing are obtained for different impact phenomena. Secondly，the deposition heat energy is calculated based on the law of conservation of energy and the cooling effectiveness of oil droplet impacting on chamber housing. Lastly，the effects of droplet temperature，shaft rotational speed，droplet diameter and air inlet temperature on the deposition characteristics are discussed. The calculated results show that，after considering the temperature variation of droplet，the rates of deposition mass and momentum are all decreased; The rates of deposition mass，momentum and heat are all decreased with the increasing of shaft rotational speed and droplet diameter，and the rate of deposition heat is increased with the increasing of air inlet temperature.

Abstract:For the two-circuit refrigerator with parallel evaporators，refrigerating cabinet and freezing cabinet could not get cooling capacity at the same time. This will lead to the increase in compressor-on time due to the fact that the compressor shuts down as the counterpart cut-out temperature in the freezing cabinet is reached. The dynamic characteristics of a parallel-evaporators refrigerator with short-cycle switching control were studied experimentally. Results showed that the refrigerant stored in the freezing-evaporator was immigrated gradually to refrigerating- evaporator due to pumping action of compressor after a startup. The capacity loss of the refrigerating evaporator due to the refrigerant migration decreased from 33.9% to 5.2%. In addition， the temperature of the freezer-sensor decreased from -16.5 ℃ to -17.8 ℃ in the first six short-cycles，but only decreased by about 0.3 ℃ in the next five short-cycles. The short-cycle switching control strategy can decrease the temperature in both refrigerating cabinet and freezing cabinet. However， the refrigerating-run time will be extended at the same time. These two factors should be comprehensive considered to make the compressor-on time shortest.

Abstract:Refrigerant migration and redistribution will occur during the on-off processes of a refrigerating system. Based on a horizontal freezer BC/BD-379HBN，dynamic characteristics of the refrigerant migration and its effects on the freezer performance were studied experimentally. Results show that the process of the start-up can be divided into three stages，i.e.，refrigerant emigrating from evaporator，evaporator two-phase section increasing stage，and evaporator two-phase section stabilized stage. In the first stage，the refrigerant flowrate through the compressor was larger than that through the capillary tube，resulting in an increase in the condensing pressure. In the second stage， condenser outlet temperature stabilized gradually with the increase in the refrigerant flowrate through the capillary tube，indicating the end of the pressure-difference rebuilt process. In the third stage，a maximum cooling capacity was obtained due to the fact that the two-phase section covered the whole evaporator tube pass. The refrigerant redistribution process occupied 3.50 minutes which was about 32% of a single compressor-on period. However，the cooling capacity during this process was small. In conclusion，a large migrating loss was introduced by the start-up refrigerant migration process of the freezer.

Abstract:Based on the measurement of the surface topography of rolled steel strip，the phenomenon and rules of surface topography transfer were analyzed. Combining with the worn surface topography of roll and the distribution of lubrication oil，the transfer model of surface topography in cold rolling was established，and by which the simulation results were verified by measured data. A set of roughness parameters were introduced to analyze the effect of lubrication film thickness on the transfer performance of electrical discharge textured roll surface topography. Numerical examples show that the roughness parameters Ra of transfer ratio decreases with the increase of oil film thickness，when the surface topography of roll under different worn condition. Furthermore， with the surface topography wear of roll， Pv of transfer ratio remains when the oil film thickness is thin，but rapidly decreases with the increase of oil film thickness when the oil film thickness is thick.

Abstract:To improve the meshing performance ol internal double helical gear with high speed，a multi-objective optimal design approach considering the influences of deformation of elastic shaft is proposed. The load distribution on tooth contact line and tooth deformation in a meshing period are got by the tooth contact analysis and loaded tooth contact analysis. The local friction coefficients of discrete points on tooth contact line are determined by the regression equation which is based on the mixed elastohydrodynamic lubrication model，and then the Blok’s basic equation is used to get the surface flash temperature with high speed. After that，applying the genetic optimization algorithm，the tooth modification values are determined to optimize the amplitude of loaded transmission error，flash temperature and load distribution. The calculation is illustrated by a numerical instance. The results show that with and without misalignment error， after the tooth modification， both ALTEs decline significantly， and the surface flash temperature obviously decreases at the coming into and out of contact zones. Meanwhile，the edge contact is avoided，and both the load distributions are improved. The calculation results of the proposed optimization design method are reliable，and the method presented is an effective means for tooth dressing of high speed gear drives.

Abstract:To study the characteristics and synchronous performance of new hydraulic synchronous multi-motor (Referred to as hydraulic multi-motor), the hydraulic multi-motor is used as synchronous motor in synchronous circuit. The functions of new synchronous circuit and traditional synchronous circuit are compared and ana1yzed, and based on the hydraulic multi-motor structure, the factors affecting on its volume efficiency are studied. The three hydraulic cylinder synchronous system constituted by hydraulic multi-motor prototype is composed to carry out the experiments, and the synchronous performance is verified. Theoretical analysis and experimental results show that the new hydraulic multi-motor not only can completely realize the function of traditional synchronous motor with fewer components and higher precision (1.0%-1.7%), but also can achieve different diameter cylinder synchronization.

Abstract:To study the dynamic response of vortex-induced vibration under different a in TrSL3 ( Transition of shear layer,2×10⁴~4×10⁴＜Re＜1×10⁵-2×10⁵),the finite-volume method is used to resolve the turbulence model of the Reynold s - averaged Navier-Stokes equation and the Spalart-Allmaras equation on the basis of OpenFOAM together with the Van Der Pol second-order equation describing the two-dimensional vortex-induced vibration of cylinder. The oscillating amplitude,frequencies and the vortex shedding structures are analyzed in detail. The initial,upper and lower branches of the synchronization phenomenon in vortex-induced vibration are captured. The results show that,the amplitude in present work is higher than that in TrSL2 and modified Griffin plot when evaluate Reynolds number under the same reduced velocity. Reynolds number plays a key role in elevating the oscillating amplitude and the synchronization range under TrSL3. The vortex-induced vibration misses upper branch and enter into the lower branch directly from initial branch in the case of high mass-damping ratio (α≥0.38),phase step occurs in oscillating frequency.

Abstract:The carbon-carbon (carbon fiber reinforced carbon matrix) composites were applied in the finger seal and the tribological behaviors were investigated using UMT-2 tribology tester under the light loads condition. The friction coefficient and the wear rate were measured. Friction and wear mechanisms were analyzed using SEM (scanning electron microscope) method. Results show that the friction coefficient and wear rate are lower when the non-woven cloth is perpendicular to sliding surface. For the higher density material,with increasing load the wear rate increases with small amplitude and the friction coefficient decreases. The frequency has less effect on the wear rate compared to the load on wear rate,and the tribological behaviors are better with increasing frequency. SEM analysis indicates as follows. First,abrasive wear occurs under low frequency and low load. Second,increasing the frequency quickens formation of the wear debris into film,and self-lubricating effect is strengthened. Last,although wear debris are quickly squeezed into film with increasing load,severe wear occurs due to fibers exposure and fracture with the film further squeezed out and peeled off. The effect of load on wear is notable when the material density is lower. Selecting higher density material and the material with non-woven cloth perpendicular to sliding surface can effectively mitigate wear.