Abstract:Whole-body humanoid robot, which regards human beings as the reference prototype, is the most representative research object and the ultimate goal of robotics, robot technology and artificial intelligence. Comprehensive review, summary and analysis of current theories and key technologies in whole-body humanoid robot, humanoid head, multi-finger hand, humanoid biped walking machine and so on are given, including review of the relevant works on humanoid robots by the author. By summarizing the current technical level of humanoid robots' development, the main technical problems and the trend of the future development are respectively discussed in the aspects of driving elements, walking stability, integrated designation and operation ability of the mechanical systems, environment adaptability and so on. References of decision making are provided for researchers and managers engaged in the relevant works of humanoid robots and their components.

Abstract:Graph optimization-based SLAM is the main method under large-scale environment. The framework of this method is composed of two parts, front-end and back-end. Be a continuation paper of our previous one, the four main back-end optimization approaches, which include least square, stochastic gradient descent, relaxation, manifold optimization, and the correspondent literatures are introduced, and two map evaluation methods are presented, that is  χ² error based and MSE error based. The trends of graph optimization-based SLAM method are predicted.

Abstract:To improve performance of sensitivity amplification control(SAC) for exoskeleton robot, genetic algorithm(GA) and RBF neural network was combined to obtain accurate dynamic model of exoskeleton robot online. Parameters of center vector and base width of RBF neural network were obtained by GA optimization, and online RBF weights learning process was constructed to obtain estimation matrix parameters of dynamics system, finally, SAC control law was deduced. Simulation results showed that the RBF network optimized by GA could learn exoskeleton dynamics model parameters online. Based on the learned model, the SAC could achieve more precise human trajectory tracking where tracking error and human-robot interaction force converged to the small neighborhood of zero simultaneously compared with those without optimization. The proposed RBF neural network with GA optimization which learned dynamics model parameters online for exoskeleton robot dynamics model could achieve highly accurate trajectory following for SAC, ultimately realize cooperative movement between human and exoskeleton.

Abstract:To decrease the straightness errors and improve the accuracy of machine tools, a spatial straightness error modeling which is based on B-Spline curves is presented. Experiments are carried out on a machine tool to obtain six serials of straightness errors by laser interferometer and a space straightness error modeling is obtained by applying the B-Spline method. Compensation is implemented by applying the error compensation system which utilizes the external mechanical origin offset function of Fanuc to impute the compensation data into CNC. Compared with the polynomial model and the interpolation model, the B-Spline model is proved to be of high accuracy. In addition, the straightness errors of the machine tool are deceased by more than 90% compared with no compensation, the machine accuracy is efficiently improved.

Abstract:To get the fault tree analysis of ETC36 CNC lathe feed system under the condition of lack of actual failure data and reliability test data, and improve the reliability of ETC36 CNC lathe feed system, an expert language evaluation method is adopted to obtain the fuzzy probability of bottom events. Based on fuzzy theory, the fault tree is established and the qualitative analysis is carried out. Various failure modes of ETC36 CNC lathe feeding system are gotton. On the basis of using expert language evaluation method, a quantitative analysis of the fault tree is made and the fuzzy probability of top event is obtained. When compared the fuzzy probability of top event with the actual probability, the corresponding confidence level 0.70 is gotton that verifies the feasibility of language experts evaluation method and the correctness of the fault tree. The fuzzy importance degree of each bottom event is calculated, and the weak links of ETC36 CNC lathe feed system is overcome. To a certain extent, the fault tree analysis of ETC36 CNC lathe feed system under the serious lack of failure probability information is finished.

Abstract:To meet the requirements of low surface residual stresses on the parts made by ultra-precision turning, by finite element analysis and tests, the micron level ultra-precision turning and simulation of aluminum alloy were done. The cutting force and temperature were analyzed, the cause and nature of machined surface residual stresses were studied, and the influence laws of the cutting depth and cutting speed on residual stresses were gotten. Simulation results show that in the cutting process the cutting force was small and the cutting temperature was low, but the unit cutting force was high. The cutting force was the leading factor in forming the compressive stress on the machined surface. The machined surface residual stresses increased with the increase of cutting depth and decreased with the increase of cutting speed. The cutting depth obviously influenced the residual stresses. The experiments of ultra-precision turning in micron level were done and the machined surface residual stresses were measured by XRD. The results of simulation were verified.

Abstract:As existing tire models were no longer appropriate for vibration analysis of mechanical elastic wheel (MEW), elastic rope model was presented based on MEW’s structural characteristics and its hinges’ feature that transmitted force by single-direction. The single and total stiffness expression and frequency response function of the model were deduced and a complete mathematical model of MEW for vibration analysis was established. According to the model vibration, calculation under C-level random rough road input was conducted, and the center displacement response of wheel hub in time domain and power spectral density response in frequency domain were obtained. By comparing the finite element simulation results, the correctness of the elastic rope model is verified and it indicates the resonant frequencies are 19 Hz～21 Hz that provides a reference for the optimization of the MEW design.

Abstract:A fill-form mixing material molding method for flow passage of turbomachinery such as hydrodynamic torque converter in the process of non-contact measurement was proposed, and the passage structure was extracted by two different materials of silicone rubber and ultra-lightweight paper clay, where silicone rubber got accurate shape of passage and paper clay supported the silicone rubber. Compared with traditional molding method with sole silicone rubber, this method overcame the shortcoming of large modeling deviation caused by deforming of silicone rubber after it was taken from flow passage but could not rebound to original shape, and the data of mapping point cloud of passage pieced by ICP algorithm coincided well with the known blade. The average deviation decreased steeply from 300.7 μm of the sole silicone rubber molding method to 28.5 μm of the mixing material molding method, and more accurate extraction and reconstruction of special flow passage was accomplished which provids a more effective reverse engineering method to measure and check the deviation in design and manufacture.

Abstract:To analyze the performance of inverse inchworm motor under different preloads, experiments are carried out based on an inverse piezoelectric inchworm motor researched and manufactured before. In the experiments, the clamping force is used to describe the preload indirectly. The clamping forces, no-load characteristics and load characteristics of the inverse piezoelectric inchworm motor are tested under four different preloads. The results show that the driving force increases first and then decreases with the increasing of preload. When the preload is low, the high velocity of motor is 1.43 mm/s, but the driving force is low. When the preload is high, the performance of inchworm motor becomes worse. The best performance can be reached under proper preload and the maximum driving force is 2.1 N. The amplitudes of vibration of driving part have been tested with different driving frequency. When the frequency is high, the amplitude of vibration decreases, and the velocity of motor first increases and then decreases with the increasing of frequency.

Abstract:According to the problem of drawing force control in the fused biconical tapering process of polarization maintaining fiber (PMF) coupler, an online computer control method of drawing force is presented, which includes the computer, drawing mechanism, rotary position encoders and a control circuit. By detecting the rotation angle of fiber clamp, the electro-magnetic force can be controlled through changing the coil current, and the real-time control of drawing force is realized. Firstly, the relationship between the electromagnetic force and drawing force is analyzed, a 3D finite element model of the permanent magnet and the coil is established, and a trajectory equation describing the permanent magnet is obtained. Then, by simulation of the magnetic field and the electro-magnetic force around the coil, the relationship among the coil current, the rotation angle of fiber clamp and the drawing force is determined. At last, by simulation, the drawing force is controlled within an error of 1.03%.

Abstract:To improve the braking power density of dual torus hydraulic retarder, the design method of blade had been studied. The tangent-arc blade design method was proposed base on the structural feature of bowed blade. On the design variables of blade wrap angles and working radiuses, the parametric modeling of periodic flow was achieved. With the Design of Experiment method (DOE), the design examples were adopted to study the braking performance on different blade parameters. Comparison with braking performance of the prototype showed that the numerical method was accurate and reliable, the relative braking torque error between simulation and experiment was within 5％, and based on the tangent-arc blade design method, the braking torque of different blade parameters had a large range of variation. With the appropriate blade parameters, the braking performance could be effectively improved.

Abstract:To suppress the idling loss of vehicular hydraulic retarder, the suppression effect of spoiler on the idling loss was investigated by 3-D flow field numerical simulation. Based on the arrangement of spoilers, the periodic calculation models with and without spoiler installed in the stator were established to reduce the cost of simulation, and the accuracy of numerical models was verified in idling condition and oil-filling condition respectively. At different rotating speed, the calculation of idling loss was further conducted for two periodic models. The braking power applied by air was calculated in idle condition, and the distribution of velocity field and pressure field were also obtained. Then the effect of spoiler disturbing air flow and reducing idling loss was comparatively analyzed. The result shows that the spoiler can impede the air circulation flow effectively, the idling loss of the hydraulic retarder can be reduced to 48.4% at the rotary speed of 3 400 r/min, and the vehicle power utilization can be enhanced efficiently.

Abstract:For a better understanding of slagging characteristics of Zhundong coal and solving its slagging problem, entrained flow reactor with multiple reaction segments was used to simulate air staging combustion condition in PC boiler. The slagging characteristics of Zhundong coal in various excess air ratio conditions was investigated, the morphology and melting characteristics and its burnout rate were analyzed using SEM-EDX and XRD. The results show that the burnout rate of Zhundong coal is more than 99％ at 1 250 ℃, and the influence of excess air ratio ranging from 0.7 to 1.0 on the char burnout is not obvious. With the excess air ratio increasing in the primary zone, the content of mullite increases, while the slagging characteristic reduces gradually. The Si, Fe, Na are enrich in slagging, while the content of Al is lower, and slagging is more serious. The aluminosilicate of iron is easy to form low temperature eutectic under lower excess air ratio, and it will cause slagging seriously. Therefore, the excess air ratio of the primary zone should be above 0.7 to avoid slagging seriously, and combustion mixed with low iron coal will reduce slagging of Zhundong coal.

Abstract:To precisely predict the internal flow characteristics and external features of Francis hydro-turbine when running off the optimal flow conditions, numerical computation based on large eddy simulation (LES) method was performed. For LES method, the results from both single-phase model and cavitation model were compared. It is revealed that LES is capable of providing better depiction for inner flow field of Francis hydro-turbine, and also, at partial flow conditions, LES method accompanying with cavitation model can capture more accurate structures for channel vortices and draft tube vortices. Moreover, LES method shows advantages for predicting the external characteristics, including the trends of flow rate and working efficiency, which are verified by the experimental results. Based on the transient simulation on the internal flow, the cavitating vortices in the runner and draft tube are captured by using Q method, and their evolutions with certain frequency are re-generated. For the condition of a=10 mm and n₁₁=64.9 r／min, the frequencies of channel vortex and vortex rope are 15 times and 0.4 times of rotating frequency, respectively. The results are in agreement with the experimental ones, thus the LES method is proved to be accurate for the complicated three-dimensional simulation.

Abstract:The impact of Coanda effect on the flow resistance coefficient of flat-walled diffusers has been studied by numerical simulation, and the results show that when Reynolds number changes in the range of 300~3 000 and the diffusion angle θ of the cone tube varies from 5° to 40°, the fluid flow to the diffusion direction goes through three stages: the stable state, the wall-attachment state and the jet deflection state, when 10°<θ<35°, the Coanda effect can be obtained easily. When Reynolds number ranging from 300 to 1 200, with the increasing of diffusion angle, the flow resistance coefficient decreases rapidly during the stable state, increases slowly among the wall-attachment state and decreases gradually in time of the jet deflection state. While Re varies from 1 800 to 3 000, the flow resistance coefficient of the wall-attachment state reaches maximum at θ=30°. The flow resistance coefficient ratio in steady state and jet condition state is basically unchanged, but decreases quickly during the wall-attachment state with the increasing of diffusion angle.

Abstract:To improve the load distribution of rollers thread, based on the relationship of deformation compatibility on two contact sides of the roller, a model of load distribution of the roller thread considering errors is established when the screw shaft withstands tension and the nut withstands compression. The load ratios among the roller thread teeth are compared with the results of direct stiffness method to verify the correctness of the presented method. Then the factors, such as load, contact angle, helix angle, number teeth of the roller thread and material Young's modulus ratio, which affect the load distribution of the roller thread are systematically studied. The results show that the smaller the load, the larger the fluctuation of load distribution on teeth of the roller thread. The negative errors are able to decrease load ratios of the fore 3 teeth of the roller thread. The load distribution is more even by decreasing the contact angle or helix angle. Increasing the number teeth leads to the decrease of the load ratios and the influence of error on load ratios. Besides, it is helpful to improve load distribution of roller thread by decreasing the Young's modulus of the screw or the nut.

Abstract:For researching the surface integrity formation of AerMet100 ultrahigh strength steel during grinding with single alundum wheel, the grinding temperature field was studied from the macro- and micro-viewpoint by means of experiments and numerical simulation. First, the constitutive model of AerMet100 was established by tests, and then an experiment for measuring grinding force and temperature was carried out. Based on the results, the grinding thermal load acting on grinding surface was determined. Finally, two kinds of FEA numerical simulation were finished. One was to simulate the macro temperature distribution in grinding zone, and another was to simulate the micro temperature field near the contact zone between grain and workpiece. Results show that the maximum temperature in macro grinding temperature field ranges from 190 ℃ to 500 ℃, and that in micro temperature field can be up to 820 ℃. The influence depth of micro grinding temperature field is 5 μm to 10 μm.

Abstract:To solve the problem of machining defects such as burrs and chipping during machining of carbon fiber reinforced plastics (CFRP), a computing method of the length of carbon fiber cut by per tooth was proposed based on fiber cutting angle. This method explained the mechanism and regularity of burrs. The results of the computation and experiment showed that the length of carbon fiber cut by per tooth and the number of total cutting edges acted on the same carbon fiber were determined by the fiber cutting angle. With the increase of fiber cutting angle, the length of carbon fiber cut by per tooth increased and the frequency of the cutting action between the fiber and cutting edge decreased. The reason for the occurrence of burrs is that the actual bending radius is larger than the minimum bending radius. The carbon fiber tended to be bent instead of being fractured. Also chipping could be found within the fiber cutting angle range of 0~90°. Burr was observed when the fiber cutting angle was in the range of 90°~180° during the verification slotting experiment. And the length of burr increased with the increase of fiber cutting angle.

Abstract:To improve the hydrodynamic performance of point absorber, the CFD method based on viscous fluid mechanics was used to simulate the buoy motion of point absorber in three-dimensional. The influences of different buoy shape, different damping coefficients, mass and motions performance were researched, and the CFD results agreed with the experimental results better than that of the potential theory. The circular column buoy was better than the circular truncated cone buoy in natural and damping oscillation, and with the enlarging of damping coefficient, the capture width ratio increased in the best damping and then decreased. The damping coefficient corresponding to the maximum capture width ratio was the best. With the enlarging of mass, the capture width ratio increased slowly and had a slight decrease.

Abstract:A method of on-line fault detection and diagnosis based on the modified DENCLUE clustering and partial binary tree support vector machine (SVM) is proposed for on-line fault diagnosis problem of bulk weighing equipment—electronic belt weigher. Firstly, in view of the fault data varying with equipment flow, a modified DENCLUE clustering algorithm is designed to realize the online fault detection by isolating the fault data after the clustering analysis of the real-time data. Secondly, the density estimation method in DENCLUE algorithm is introduced into the support vector machine, and then an improved BTSVM, in which the separability measure and binary tree structure is built based on the similar density within class and between class, is presented to recognize the detected fault on-line. The improved BTSVM is also verified the superiority by the standard dataset. Finally, the proposed online fault detection and diagnosis model is verified more suitable for the online fault detection and diagnosis of bulk weighing equipment by the array belt weigher experiments.