A two degrees of freedom （DOF） positioning stage using novel linear ultrasonic motors is presented. The stage mainly consists of two linear ultrasonic motors, linear guides and tables. It can realize the long stroke...A two degrees of freedom （DOF） positioning stage using novel linear ultrasonic motors is presented. The stage mainly consists of two linear ultrasonic motors, linear guides and tables. It can realize the long stroke and reversible controlled motion in two directions. The wheel-shape linear ultrasonic motor applied in the stage utilizes two fourth-bending modes of non-uniform beam in orthogonal directions. Quick response, no backlash, high resolution, power-off self-braking, and long stroke are the attractive characteristics of the linear positioning stage. Experimental results show that z and y-direction tables can reach the destination without overshoot and the error is less than 2μm by using two linear encoders with a resolution of 1 μm. In the open-loop mode, the positioning stage achieves 1μm resolution at 0. 25 ms driving time.展开更多
The operating principle of a lead screw linear ultrasonic motor using bending vibration modes is analyzed. The simplified beam bending vibration model is used to analyze the dynamics characteristics of the motor. Moti...The operating principle of a lead screw linear ultrasonic motor using bending vibration modes is analyzed. The simplified beam bending vibration model is used to analyze the dynamics characteristics of the motor. Motion trajectory equations are derived for driving points of the stator. The motor operation and driving mechanisms are investigated. The vibration modes and the construction of the motor are analyzed by using the finite element method （FEM）. A prototype motor is built and its stator dimension is 13 mm × 13 mm× 30 mm. The motor is experimentally characterized and the maximum output force of 5- 2 N is obtained.展开更多
The pitting corrosion behaviors of 7A60 aluminum alloy in the retrogression and re-aging （RRA） temper were investigated by electrochemical impedance spectroscopy （EIS） and electrochemical noise （EN） techniques, ...The pitting corrosion behaviors of 7A60 aluminum alloy in the retrogression and re-aging （RRA） temper were investigated by electrochemical impedance spectroscopy （EIS） and electrochemical noise （EN） techniques, and the microstructure and the second phase content of the alloy were observed and determined by scanning electron microscopy （SEM） and energy dispersive spectrometer （EDS）. The results show that there exist two different corrosion stages for 7A60 alloy in 3.5%NaCl solution, and the corrosion process can be detected by the appearance of EIS spectrum with two capacitive time constants and the wavelet fractal dimension D extracted from EN. SEM and EDS results also demonstrate that severe pitting corrosion in 7A60 alloy is mainly caused by electrochemical active MgZn2 particles, secondly by Al2MgCu and Mg2Si. Al7Cu2Fe particles make little contribution to the pitting corrosion of 7A60 alloy.展开更多
The ultrasonic motor is a sort of new type of micromotor with special structure. By use of piezoelectric converse effect of ceramics, the electrical energy is transformed into mechanical energy. Its operating principl...The ultrasonic motor is a sort of new type of micromotor with special structure. By use of piezoelectric converse effect of ceramics, the electrical energy is transformed into mechanical energy. Its operating principle is quite different from that of the traditional motors. In this paper the equivalent circuits of the ring stator and even the whole motor are proposed after studying the equivalent circuit of piezoelectric vibrator. Then the paper makes detailed analyses of each part of the control system, which has been simplified by the equivalent circuit. The theory in this paper has been proved through experiments.展开更多
A four-stage monolithic microwave integrated circuits （MMIC） low noise amplifier （LNA） operating from 23 to 36GHz is reported using commercially available 0.15μm PHEMT technology. The LNA is self-biased. To achie...A four-stage monolithic microwave integrated circuits （MMIC） low noise amplifier （LNA） operating from 23 to 36GHz is reported using commercially available 0.15μm PHEMT technology. The LNA is self-biased. To achieve a low noise characteristic, careful optimizations of gate width are performed to reduce gate resistance. Absorption circuits and an elaborate bias structure with a resistor-capacitor network are employed to improve stability. Multiple resonance points and negative feedback technologies are used to widen the bandwidth. Measurements show a noise figure （NF） of less than 2.0dB,and the lowest NF is only 1.6dB at a frequency of 31GHz. In the whole operation band,the LNA has a gain of higher than 26dB,and an input return loss and output return loss of more than 11 and 13dB,respectively. The output power at ldB compression gain of 36GHz is about 14dBm. The chip area is 2.4mm ×1mm.展开更多
Nanometer Cu singly doped and Cu/Al co-doped nickel hydroxides were synthesized by ultrasonic-assisted precipitation method. Their crystal structure, particle size, morphology, tap density and electrochemical performa...Nanometer Cu singly doped and Cu/Al co-doped nickel hydroxides were synthesized by ultrasonic-assisted precipitation method. Their crystal structure, particle size, morphology, tap density and electrochemical performance were investigated. The results show that the samples have a-phase structure with narrow particle size distribution. Cu singly doped nano-Ni（OH）2 contains irregular particles, while Cu/Al co-doped nano-Ni（OH）2 displays a quasi-spherical shape and has a relatively higher tap density. Composite electrodes were prepared by mixing 8% （mass fraction） nanometer samples with commercial micro-size spherical nickel. The charge/discharge test and cyclic voltammetry results indicate that the electrochemical performance of Cu/Al co-doped nano-Ni（OH）2 is better than that of Cu singly doped nano-Ni（OH）2, the former＇s discharge capacity reaches 330 mA.h/g at 0.2C, 12 mA.h/g and 91 mA.h/g larger than that of Cu singly doped sample and pure spherical nickel electrode, respectively. Moreover, the proton diffusion coefficient of Cu/Al co-doped sample is 52.3% larger than that of Cu singly doped sample.展开更多
In planning and executing marine controlled-source electromagnetic methods, seafloor electromagnetic receivers must overcome the problems of noise, clock drift, and power consumption. To design a receiver that perform...In planning and executing marine controlled-source electromagnetic methods, seafloor electromagnetic receivers must overcome the problems of noise, clock drift, and power consumption. To design a receiver that performs well and overcomes the abovementioned problems, we performed forward modeling of the E-field abnormal response and established the receiver＇s characteristics. We describe the design optimization and the properties of each component, that is, low-noise induction coil sensor, low-noise Ag/AgCI electrode, low-noise chopper amplifier, digital temperature-compensated crystal oscillator module, acoustic telemetry modem, and burn wire system. Finally, we discuss the results of onshore and offshore field tests to show the effectiveness of the developed seafloor electromagnetic receiver and its performance： typical E-field noise of 0.12 nV/m/rt（Hz） at 0.5 Hz, dynamic range higher than 120 dB, clock drift lower than 1 ms/day, and continuous operation of at least 21 days.展开更多
This paper presents a fully integrated 4 8GHz VCO with an invention——symmetrical noise filter technique.This VCO,with relatively low phase noise and large tuning range of 716MHz,is fabricated with the 0 25μm SMIC...This paper presents a fully integrated 4 8GHz VCO with an invention——symmetrical noise filter technique.This VCO,with relatively low phase noise and large tuning range of 716MHz,is fabricated with the 0 25μm SMIC CMOS process.The oscillator consumes 6mA from 2 5V supply.Another conventional VCO is also designed and simulated without symmetrical noise filter on the same process,which also consumes 6mA current and is with the same tuning.Simulation result describes that the first VCO’ phase noise is 6dBc/Hz better than the latter’s at the same offset frequency from 4 8GHz.Measured phase noise at 1MHz away from the carrier in this 4 8GHz VCO with symmetrical noise filter is -123 66dBc/Hz.This design is suitable for the usage in a phase locked loop and other consumer electronics.It is amenable for future technologies and allows easy porting to different CMOS manufacturing process.展开更多
Cadmium was replaced by zinc in ammoniacal system using an electrically enhanced method under ultrasonic waves.Five main influencing factors were investigated by a single-factor experiment to determine the optimum par...Cadmium was replaced by zinc in ammoniacal system using an electrically enhanced method under ultrasonic waves.Five main influencing factors were investigated by a single-factor experiment to determine the optimum parameters.Cyclic voltammetry and linear sweep voltammetry were applied to investigating the reaction mechanism of electrically enhanced cementation of cadmium on a zinc plate.The optimum parameters were a temperature of 35℃,a cathode-to-anode area ratio of 1:2,an anode current density of 15 A/m2,an ultrasonic frequency of 40 kHz a reaction time of 6 h and an ultrasonic power of 100 W.The extraction rate was 99.21%,and the production of byproduct“floating sponge cadmium”was inhibited.The analysis of the cyclic voltammetry and linear sweep voltammetry diagrams showed that ultrasonic waves can promote and accelerate the replacement reaction,decrease the voltage requirement of the electrically enhanced replacement reaction,and change the reaction steps.In addition,increasing the temperature and ultrasonic power can promote and accelerate electrically enhanced replacement reactions and decrease the electric potential requirement.展开更多
The effects of low frequency electromagnetic (LFEC) field and ultrasonic (US) field on the microstructures, macrosegregation of alloying elements and the mechanical properties of DC cast AZ80 alloy were studied. The r...The effects of low frequency electromagnetic (LFEC) field and ultrasonic (US) field on the microstructures, macrosegregation of alloying elements and the mechanical properties of DC cast AZ80 alloy were studied. The results show that both LFEC and US fields can refine the grains of the billets, which results in the increase in mechanical properties and uniformity of alloying element distribution. The effective refinement takes place on the edge of ingots when LFEC field is applied, while in the center of billets when field US is adopted. Combined the characteristics of LFEC and US fields, a new process for direct-chilling (DC) casting of Mg-electromagnetic-ultrasonic (ECUS) casting is developed, by which the grains are refined significantly and are more uniform in the whole ingots, and the mechanical properties of the ingots are improved.展开更多
The ultrasonic motor (USM) possesses heavy nonlinearities which vary with driving conditions and load-dependent characteristics such as the dead-zone. In this paper, an identification method for the rotary travelling-...The ultrasonic motor (USM) possesses heavy nonlinearities which vary with driving conditions and load-dependent characteristics such as the dead-zone. In this paper, an identification method for the rotary travelling-wave type ultrasonic motor (RTWUSM) with dead-zone is proposed based on a modified Hammerstein model structure. The driving voltage contributing effect on the nonlinearities of the RTWUSM was transformed to the change of dynamic parameters against the driving voltage. The dead-zone of the RTWUSM is identified based upon the above transformation. Experiment results showed good agreement be- tween the output of the proposed model and actual measured output.展开更多
A new method for optimizing a butterfly-shaped linear ultrasonic motor was proposed to maximize its mechanical output. The finite element analysis technology and response surface methodology were combined together to ...A new method for optimizing a butterfly-shaped linear ultrasonic motor was proposed to maximize its mechanical output. The finite element analysis technology and response surface methodology were combined together to realize the optimal design of the butterfly-shaped linear ultrasonic motor. First, the operation principle of the motor was introduced. Second, the finite element parameterized model of the stator of the motor was built using ANSYS parametric design language and some structure parameters of the stator were selected as design variables. Third, the sample points were selected in design variable space using latin hypercube Design. Through modal analysis and harmonic response analysis of the stator based on these sample points, the target responses were obtained. These sample points and response values were combined together to build a response surface model. Finally, the simplex method was used to find the optimal solution. The experimental results showed that many aspects of the design requirements of the butterfly-shaped linear ultrasonic motor have been fulfilled. The prototype motor fabricated based on the optimal design result exhibited considerably high dynamic performance, such as no-load speed of 873 ram/s, maximal thrust of 27.5 N, maximal efficiency of 43%, and thrust-weight ratio of 45.8.展开更多
A unilateral self-locking mechanism(USM) was proposed to increase the tractive ability of the inchworm in-pipe robots for pipeline inspection.The USM was basically composed of a cam,a torsional spring and an axis.The ...A unilateral self-locking mechanism(USM) was proposed to increase the tractive ability of the inchworm in-pipe robots for pipeline inspection.The USM was basically composed of a cam,a torsional spring and an axis.The self-locking and virtual work principles were applied to studying the basic self-locking condition of the USM.In order to make the cooperation between the crutch and telescopic mechanism more harmonical,the unlocking time of the USM was calculated.A set of parameters were selected to build a virtual model and fabricate a prototype.Both the simulation and performance experiments were carried out in a pipe with a nominal inside diameter of 160 mm.The results show that USM enables the robot to move quickly in one way,and in the other way it helps the robot get self-locking with the pipe wall.The traction of the inchworm robot can rise to 1.2 kN,beyond the limitation of friction of 0.497 kN.展开更多
In order to promote the tolerance and controllability of the multi-degree-of-freedom(M-DOF) ultrasonic motor, a novel two-degree-of-freedom(2-DOF) spherical ultrasonic motor using three traveling-wave type annular sta...In order to promote the tolerance and controllability of the multi-degree-of-freedom(M-DOF) ultrasonic motor, a novel two-degree-of-freedom(2-DOF) spherical ultrasonic motor using three traveling-wave type annular stators was put forward. Firstly,the structure and working principle of this motor were introduced, especially a spiral spring as the preload applied component was designed for adaptive adjustment. Then, the friction drive model of 2-DOF spherical motor was built up from spatial geometric relation between three annular stators and the spherical rotor which was used to analyze the mechanical characteristics of the motor.The optimal control strategy for minimum norm solution of three stators' angular velocity was proposed, using Moore-Penrose generalized inverse matrix. Finally, a 2-DOF prototype was fabricated and tested, which ran stably and controllably. The maximum no-load velocity and stall torque are 92 r/min and 90 m N·m, respectively. The 2-DOF spherical ultrasonic motor has compact structure, easy assembly, good performance and stable operation.展开更多
Structure of the octagon-type ultrasonic motor was proposed and designed so as to allow the motor to drive small actuator. The stator of the motor consisted of the octagon shape elastic body and four rectangular plate...Structure of the octagon-type ultrasonic motor was proposed and designed so as to allow the motor to drive small actuator. The stator of the motor consisted of the octagon shape elastic body and four rectangular plate ceramics. The four ceramics were attached to outer surfaces of the octagon elastic body. The same phase voltages were applied to the ceramics on horizontal surfaces, and 90° phase difference voltages were applied to the ceramics on vertical surfaces. When the AC voltage with 90° phase difference was applied in ceramics, the elliptical displacement of unimorph bars was generated by generating bending vibration. To find the maximum displacement model that generates elliptical displacement at the centers of the inner surfaces, the finite element analysis program ATILA was used. The analyzed results were compared to the experimental results. As a result, the speed and torque are increased linearly by increasing the input voltage and the speed of motors can be controlled by changing the applied voltages.展开更多
Applications are limited at present because the currently available ultrasonic motors (USMs) do not provide suffi-ciently high torque and power. The conventional travelling-wave USM needs the bearing to support, which...Applications are limited at present because the currently available ultrasonic motors (USMs) do not provide suffi-ciently high torque and power. The conventional travelling-wave USM needs the bearing to support, which required lubricant. To solve the above problem, a bearingless travelling-wave USM is designed. First, a novel structure of the two-sided USM consisting of a two-sided teeth stator and two disk-type rotors is designed. And the excitation principle of the two-sided travelling-wave USM is analyzed. Then, using ANSYS software, we set up the model of the stator to predict the excitation frequency and modal response of the stator. The shape of the vibration mode was obtained. Last, the load characteristics of the USM are measured using ex-perimental method. The maximum stall torque and the no-load speed were obtained. The results showed that the characteristics of the two-sided USM are better than those of the conventional one-sided USM.展开更多
基金the National Natural Science Foundation of China (50735002)~~
文摘A two degrees of freedom （DOF） positioning stage using novel linear ultrasonic motors is presented. The stage mainly consists of two linear ultrasonic motors, linear guides and tables. It can realize the long stroke and reversible controlled motion in two directions. The wheel-shape linear ultrasonic motor applied in the stage utilizes two fourth-bending modes of non-uniform beam in orthogonal directions. Quick response, no backlash, high resolution, power-off self-braking, and long stroke are the attractive characteristics of the linear positioning stage. Experimental results show that z and y-direction tables can reach the destination without overshoot and the error is less than 2μm by using two linear encoders with a resolution of 1 μm. In the open-loop mode, the positioning stage achieves 1μm resolution at 0. 25 ms driving time.
基金Supported by the National Natural Science Foundation of China(50575103, 50735002)~~
文摘The operating principle of a lead screw linear ultrasonic motor using bending vibration modes is analyzed. The simplified beam bending vibration model is used to analyze the dynamics characteristics of the motor. Motion trajectory equations are derived for driving points of the stator. The motor operation and driving mechanisms are investigated. The vibration modes and the construction of the motor are analyzed by using the finite element method （FEM）. A prototype motor is built and its stator dimension is 13 mm × 13 mm× 30 mm. The motor is experimentally characterized and the maximum output force of 5- 2 N is obtained.
基金Project(13JCZDJC29500)supported by the Key Project of Tianjin Natural Science Foundation,ChinaProjects(2011CB610505,2014CB046801)supported by the National Basic Research Program of ChinaProject(20120032110029)supported by the Specialized Research Fund for the Doctoral Program of Higher Education,China
文摘The pitting corrosion behaviors of 7A60 aluminum alloy in the retrogression and re-aging （RRA） temper were investigated by electrochemical impedance spectroscopy （EIS） and electrochemical noise （EN） techniques, and the microstructure and the second phase content of the alloy were observed and determined by scanning electron microscopy （SEM） and energy dispersive spectrometer （EDS）. The results show that there exist two different corrosion stages for 7A60 alloy in 3.5%NaCl solution, and the corrosion process can be detected by the appearance of EIS spectrum with two capacitive time constants and the wavelet fractal dimension D extracted from EN. SEM and EDS results also demonstrate that severe pitting corrosion in 7A60 alloy is mainly caused by electrochemical active MgZn2 particles, secondly by Al2MgCu and Mg2Si. Al7Cu2Fe particles make little contribution to the pitting corrosion of 7A60 alloy.
文摘The ultrasonic motor is a sort of new type of micromotor with special structure. By use of piezoelectric converse effect of ceramics, the electrical energy is transformed into mechanical energy. Its operating principle is quite different from that of the traditional motors. In this paper the equivalent circuits of the ring stator and even the whole motor are proposed after studying the equivalent circuit of piezoelectric vibrator. Then the paper makes detailed analyses of each part of the control system, which has been simplified by the equivalent circuit. The theory in this paper has been proved through experiments.
文摘A four-stage monolithic microwave integrated circuits （MMIC） low noise amplifier （LNA） operating from 23 to 36GHz is reported using commercially available 0.15μm PHEMT technology. The LNA is self-biased. To achieve a low noise characteristic, careful optimizations of gate width are performed to reduce gate resistance. Absorption circuits and an elaborate bias structure with a resistor-capacitor network are employed to improve stability. Multiple resonance points and negative feedback technologies are used to widen the bandwidth. Measurements show a noise figure （NF） of less than 2.0dB,and the lowest NF is only 1.6dB at a frequency of 31GHz. In the whole operation band,the LNA has a gain of higher than 26dB,and an input return loss and output return loss of more than 11 and 13dB,respectively. The output power at ldB compression gain of 36GHz is about 14dBm. The chip area is 2.4mm ×1mm.
基金Project (10774030) supported by the National Natural Science Foundation of ChinaProject (S2012010009955) supported by the Guangdong Province Natural Science Foundation of ChinaProject (12C232111916) supported by the Science and Technology Program of Guangzhou City of China
文摘Nanometer Cu singly doped and Cu/Al co-doped nickel hydroxides were synthesized by ultrasonic-assisted precipitation method. Their crystal structure, particle size, morphology, tap density and electrochemical performance were investigated. The results show that the samples have a-phase structure with narrow particle size distribution. Cu singly doped nano-Ni（OH）2 contains irregular particles, while Cu/Al co-doped nano-Ni（OH）2 displays a quasi-spherical shape and has a relatively higher tap density. Composite electrodes were prepared by mixing 8% （mass fraction） nanometer samples with commercial micro-size spherical nickel. The charge/discharge test and cyclic voltammetry results indicate that the electrochemical performance of Cu/Al co-doped nano-Ni（OH）2 is better than that of Cu singly doped nano-Ni（OH）2, the former＇s discharge capacity reaches 330 mA.h/g at 0.2C, 12 mA.h/g and 91 mA.h/g larger than that of Cu singly doped sample and pure spherical nickel electrode, respectively. Moreover, the proton diffusion coefficient of Cu/Al co-doped sample is 52.3% larger than that of Cu singly doped sample.
基金sponsored by the 863 Program(No.2009AA09A2012012AA09A201)+1 种基金China Geological Survey Project(No.201100307)the Fundamental Research Funds of the Ministry of Education for the Central Universities(No.2652011249)
文摘In planning and executing marine controlled-source electromagnetic methods, seafloor electromagnetic receivers must overcome the problems of noise, clock drift, and power consumption. To design a receiver that performs well and overcomes the abovementioned problems, we performed forward modeling of the E-field abnormal response and established the receiver＇s characteristics. We describe the design optimization and the properties of each component, that is, low-noise induction coil sensor, low-noise Ag/AgCI electrode, low-noise chopper amplifier, digital temperature-compensated crystal oscillator module, acoustic telemetry modem, and burn wire system. Finally, we discuss the results of onshore and offshore field tests to show the effectiveness of the developed seafloor electromagnetic receiver and its performance： typical E-field noise of 0.12 nV/m/rt（Hz） at 0.5 Hz, dynamic range higher than 120 dB, clock drift lower than 1 ms/day, and continuous operation of at least 21 days.
文摘This paper presents a fully integrated 4 8GHz VCO with an invention——symmetrical noise filter technique.This VCO,with relatively low phase noise and large tuning range of 716MHz,is fabricated with the 0 25μm SMIC CMOS process.The oscillator consumes 6mA from 2 5V supply.Another conventional VCO is also designed and simulated without symmetrical noise filter on the same process,which also consumes 6mA current and is with the same tuning.Simulation result describes that the first VCO’ phase noise is 6dBc/Hz better than the latter’s at the same offset frequency from 4 8GHz.Measured phase noise at 1MHz away from the carrier in this 4 8GHz VCO with symmetrical noise filter is -123 66dBc/Hz.This design is suitable for the usage in a phase locked loop and other consumer electronics.It is amenable for future technologies and allows easy porting to different CMOS manufacturing process.
基金Project (51574294) supported by the National Natural Science Foundation of ChinaProject (2018zzts447) supported by the Fundamental Research Funds for the Central Universities of Central South University, China
文摘Cadmium was replaced by zinc in ammoniacal system using an electrically enhanced method under ultrasonic waves.Five main influencing factors were investigated by a single-factor experiment to determine the optimum parameters.Cyclic voltammetry and linear sweep voltammetry were applied to investigating the reaction mechanism of electrically enhanced cementation of cadmium on a zinc plate.The optimum parameters were a temperature of 35℃,a cathode-to-anode area ratio of 1:2,an anode current density of 15 A/m2,an ultrasonic frequency of 40 kHz a reaction time of 6 h and an ultrasonic power of 100 W.The extraction rate was 99.21%,and the production of byproduct“floating sponge cadmium”was inhibited.The analysis of the cyclic voltammetry and linear sweep voltammetry diagrams showed that ultrasonic waves can promote and accelerate the replacement reaction,decrease the voltage requirement of the electrically enhanced replacement reaction,and change the reaction steps.In addition,increasing the temperature and ultrasonic power can promote and accelerate electrically enhanced replacement reactions and decrease the electric potential requirement.
基金Projects(2007CB613701, 2007CB613702) supported by the National Basic Research Program of ChinaProjects(50974037, 50904018) supported by the National Natural Science Foundation of China+1 种基金Project(NCET-08-0098) supported by New Century Excellent Talents in Chinese UniversityProject(N90209002) supported by the Special Foundation for Basic Scientific Research of Central Colleges
文摘The effects of low frequency electromagnetic (LFEC) field and ultrasonic (US) field on the microstructures, macrosegregation of alloying elements and the mechanical properties of DC cast AZ80 alloy were studied. The results show that both LFEC and US fields can refine the grains of the billets, which results in the increase in mechanical properties and uniformity of alloying element distribution. The effective refinement takes place on the edge of ingots when LFEC field is applied, while in the center of billets when field US is adopted. Combined the characteristics of LFEC and US fields, a new process for direct-chilling (DC) casting of Mg-electromagnetic-ultrasonic (ECUS) casting is developed, by which the grains are refined significantly and are more uniform in the whole ingots, and the mechanical properties of the ingots are improved.
基金Project supported by the National Natural Science Foundation of China (No. 60572055)the Natural Science Foundation of Guangxi Province (No. 0339068), China
文摘The ultrasonic motor (USM) possesses heavy nonlinearities which vary with driving conditions and load-dependent characteristics such as the dead-zone. In this paper, an identification method for the rotary travelling-wave type ultrasonic motor (RTWUSM) with dead-zone is proposed based on a modified Hammerstein model structure. The driving voltage contributing effect on the nonlinearities of the RTWUSM was transformed to the change of dynamic parameters against the driving voltage. The dead-zone of the RTWUSM is identified based upon the above transformation. Experiment results showed good agreement be- tween the output of the proposed model and actual measured output.
基金Projects(51275235, 50975135) supported by the National Natural Science Foundation of ChinaProject(U0934004) supported by the Natural Science Foundation of Guangdong Province, ChinaProject(2011CB707602) supported by the National Basic Research Program of China
文摘A new method for optimizing a butterfly-shaped linear ultrasonic motor was proposed to maximize its mechanical output. The finite element analysis technology and response surface methodology were combined together to realize the optimal design of the butterfly-shaped linear ultrasonic motor. First, the operation principle of the motor was introduced. Second, the finite element parameterized model of the stator of the motor was built using ANSYS parametric design language and some structure parameters of the stator were selected as design variables. Third, the sample points were selected in design variable space using latin hypercube Design. Through modal analysis and harmonic response analysis of the stator based on these sample points, the target responses were obtained. These sample points and response values were combined together to build a response surface model. Finally, the simplex method was used to find the optimal solution. The experimental results showed that many aspects of the design requirements of the butterfly-shaped linear ultrasonic motor have been fulfilled. The prototype motor fabricated based on the optimal design result exhibited considerably high dynamic performance, such as no-load speed of 873 ram/s, maximal thrust of 27.5 N, maximal efficiency of 43%, and thrust-weight ratio of 45.8.
基金Project(2007AA04Z256) supported by the National High-Tech Research and Development Program of China
文摘A unilateral self-locking mechanism(USM) was proposed to increase the tractive ability of the inchworm in-pipe robots for pipeline inspection.The USM was basically composed of a cam,a torsional spring and an axis.The self-locking and virtual work principles were applied to studying the basic self-locking condition of the USM.In order to make the cooperation between the crutch and telescopic mechanism more harmonical,the unlocking time of the USM was calculated.A set of parameters were selected to build a virtual model and fabricate a prototype.Both the simulation and performance experiments were carried out in a pipe with a nominal inside diameter of 160 mm.The results show that USM enables the robot to move quickly in one way,and in the other way it helps the robot get self-locking with the pipe wall.The traction of the inchworm robot can rise to 1.2 kN,beyond the limitation of friction of 0.497 kN.
基金Project(51107111)supported by the National Natural Science Foundation of China
文摘In order to promote the tolerance and controllability of the multi-degree-of-freedom(M-DOF) ultrasonic motor, a novel two-degree-of-freedom(2-DOF) spherical ultrasonic motor using three traveling-wave type annular stators was put forward. Firstly,the structure and working principle of this motor were introduced, especially a spiral spring as the preload applied component was designed for adaptive adjustment. Then, the friction drive model of 2-DOF spherical motor was built up from spatial geometric relation between three annular stators and the spherical rotor which was used to analyze the mechanical characteristics of the motor.The optimal control strategy for minimum norm solution of three stators' angular velocity was proposed, using Moore-Penrose generalized inverse matrix. Finally, a 2-DOF prototype was fabricated and tested, which ran stably and controllably. The maximum no-load velocity and stall torque are 92 r/min and 90 m N·m, respectively. The 2-DOF spherical ultrasonic motor has compact structure, easy assembly, good performance and stable operation.
基金Project supported by the Second Stage of Brain Korea 21 Projectssupported by the National Research Foundation of Korea (NRF) Grant funded by the Korea government (MEST) [No.2011-0030806]
文摘Structure of the octagon-type ultrasonic motor was proposed and designed so as to allow the motor to drive small actuator. The stator of the motor consisted of the octagon shape elastic body and four rectangular plate ceramics. The four ceramics were attached to outer surfaces of the octagon elastic body. The same phase voltages were applied to the ceramics on horizontal surfaces, and 90° phase difference voltages were applied to the ceramics on vertical surfaces. When the AC voltage with 90° phase difference was applied in ceramics, the elliptical displacement of unimorph bars was generated by generating bending vibration. To find the maximum displacement model that generates elliptical displacement at the centers of the inner surfaces, the finite element analysis program ATILA was used. The analyzed results were compared to the experimental results. As a result, the speed and torque are increased linearly by increasing the input voltage and the speed of motors can be controlled by changing the applied voltages.
基金Project (No. 50175018) supported by the National Natural ScienceFoundation of China
文摘Applications are limited at present because the currently available ultrasonic motors (USMs) do not provide suffi-ciently high torque and power. The conventional travelling-wave USM needs the bearing to support, which required lubricant. To solve the above problem, a bearingless travelling-wave USM is designed. First, a novel structure of the two-sided USM consisting of a two-sided teeth stator and two disk-type rotors is designed. And the excitation principle of the two-sided travelling-wave USM is analyzed. Then, using ANSYS software, we set up the model of the stator to predict the excitation frequency and modal response of the stator. The shape of the vibration mode was obtained. Last, the load characteristics of the USM are measured using ex-perimental method. The maximum stall torque and the no-load speed were obtained. The results showed that the characteristics of the two-sided USM are better than those of the conventional one-sided USM.
