The forces of contraction and expansion about the seasons in tourism behave like an imaginary mechanical tourist spring.The article discusses tourist activities in Bulgaria from 2009 to 2020,predictions concerning Cov...The forces of contraction and expansion about the seasons in tourism behave like an imaginary mechanical tourist spring.The article discusses tourist activities in Bulgaria from 2009 to 2020,predictions concerning Covid-19,and tendencies expected in the last quarter of 2021 till the end of 2022 on data published by the National Statistics Institute and Eurostat.The system’s dynamics observed before the pandemic crisis in tourism resembles the action of a mechanical spring that shrinks and extends,and we can empirically analyze the process of tourism activities.The study of this elasticity process of the system allows establishing a model with positive characteristics of the dynamics and further dealing with problems,better clarity in analysis and modeling of prognosis based on the potential of an imaginary mechanical spring concerning the possibility of the tourist destination.展开更多
Being di erent from avoidance of singularity of closed-loop linkages, this paper employs the kinematic singularity to construct compliant mechanisms with expected nonlinear sti ness characteristics to enrich the metho...Being di erent from avoidance of singularity of closed-loop linkages, this paper employs the kinematic singularity to construct compliant mechanisms with expected nonlinear sti ness characteristics to enrich the methods of compliant mechanisms synthesis. The theory for generating kinetostatic nonlinear sti ness characteristic by the kinematic limb-singularity of a crank-slider linkage is developed. Based on the principle of virtual work, the kinetostatic model of the crank-linkage with springs is established. The influences of spring sti ness on the toque-position angle relation are analyzed. It indicates that corresponding spring sti ness may generate one of four types of nonlinear sti ness characteristics including the bi-stable, local negative-sti ness, zero-sti ness or positive-sti ness when the mechanism works around the kinematic limb-singularity position. Thus the compliant mechanism with an expected sti ness characteristic can be constructed by employing the pseudo rigid-body model of the mechanism whose joints or links are replaced by corresponding flexures. Finally, a tri-symmetrical constant-torque compliant mechanism is fabricated,where the curve of torque-position angle is obtained by an experimental testing. The measurement indicates that the compliant mechanism can generate a nearly constant-torque zone.展开更多
Because the melting point of the alkalis is very high and the metal activity is strong, the common pressure sensor can＇t be used to measure pressure of liquid metal. In this paper, a differential transformer differen...Because the melting point of the alkalis is very high and the metal activity is strong, the common pressure sensor can＇t be used to measure pressure of liquid metal. In this paper, a differential transformer differential pressure sensor for measuring liquid alkalis pressure is designed, the working principle and specific design plan of the sensor are introduced, the standard current signal （ 4 -20 mA） or digital communication RS485 can be output according to the needs, and the functions of remote monitoring and data optimization can be realized through the LAN interface.展开更多
Retinal surgery is one of the most delicate and complex operations,which is close to or even beyond the physiological limitation of the human hand.Robots have demonstrated the ability to filter hand tremors and motion...Retinal surgery is one of the most delicate and complex operations,which is close to or even beyond the physiological limitation of the human hand.Robots have demonstrated the ability to filter hand tremors and motion scaling which has a promising output in microsurgery.Here,we present a novel soft micron accuracy robot(SMAR)for retinal surgery and achieve a more precise and safer operation.A remote center of motion(RCM)parallelogram structure with a double spring adaptive balancing mechanism is designed and optimized to achieve precise motion and safer operation.The deviation from the expected trajectory with manual operation and robot-assisted operation is 143.06μm±91.27μm vs 26.39μm±13.22μm,which has been significantly improved}.We evaluated the safety performance of SMAR in live animals.Furthermore,preliminary human clinical trials showed that the robot-assisted has less drift compared to the manual operation with 41.07μm±20.78μm vs 299.66μm±85.84μm.The visual acuity with LogMAR of cases showed higher improvement in the robot-assisted group preliminary,which for manual of 0.78±0.44 vs robot-assisted 1.24±0.70 with no statistically significant difference.This study provides promising options for robot-assisted with very experienced surgeons in the most challenging microsurgery.The system has the potential to effectively reduce the training curve of doctors and alleviate the shortage of ophthalmic surgeons,which is very important for rural areas and underdeveloped countries.展开更多
The small dimensions of microfabricated devices present challenges in applications such as inertial sensing,where a larger proofmass is necessary for enhanced sensitivity.An effective approach to addressing the limita...The small dimensions of microfabricated devices present challenges in applications such as inertial sensing,where a larger proofmass is necessary for enhanced sensitivity.An effective approach to addressing the limitations of linear sensing is to use nonlinear mechanisms that adapt the device’s response according to different operating conditions.This paper introduces a new nonlinear spring mechanism for use in microsensors that harnesses the buckling phenomenon to achieve stiffness softening.The proposed mechanism utilizes a micro-arm to apply an eccentric axial load to an inclined beam,causing it to buckle in a controlled manner under a specified load.Once buckled,linear springs dominate the response of the system.We demonstrate that this method results in a smaller bias displacement compared to previously reported techniques based on snap-through behaviour,leading to potential reductions in device size and improvements in operational range.The behaviour is analytically modelled and verified through simulations.A prototype device was designed and microfabricated to experimentally validate the design principles.Compared to pre-curved nonlinear springs,the proposed design results in an 11-fold reduction in bias force,a 100-fold reduction in bias displacement,and a reduction in mechanical stiffness by a factor of 520.These results were verified through experiments conducted on a microfabricated accelerometer with an on-chip optical interferometer.Test results reveal an extended linear range of better than 150mg,a bias force of 0.3 mN,and a bias displacement of 10μm,measured with an integrated optical interferometer with a displacement noise floor of 40 pm/√ Hz p at 2 Hz and sensitivity of 194°=mg.展开更多
Static balancing for a manipulator＇s weight is necessary in terms of energy saving and performance improvement. This paper proposes a method to design balancing devices for articulated robots in industry, based on ro...Static balancing for a manipulator＇s weight is necessary in terms of energy saving and performance improvement. This paper proposes a method to design balancing devices for articulated robots in industry, based on robotic dynamics. Full design details for the balancing system using springs are presented from two aspects： One is the optimization for the position of the balancing system; the other is the design of the spring parameters. As examples, two feasible balancing devices are proposed, based on different robotic structures： The first solution consists of linkages and springs; the other consists of pulleys, cross mechanisms and （hydro-） pneumatic springs. Then the two solutions are compared. Pneumatic, hydro-pneumatic and mechanical springs are discussed and their parameters are decided according to the requirements of torque compensation. Numerical results show that with the proper design using the methodology presented in this paper, an articulated robot can be statically balanced perfectly in all configurations. This paper therefore provides a design method of the balancing system for other similar structures.展开更多
Various bistable mechanisms have been extensively investigated in wave energy utilization.However,there is little application of their physical realization in two-body wave energy converters(WECs)suitable for offshore...Various bistable mechanisms have been extensively investigated in wave energy utilization.However,there is little application of their physical realization in two-body wave energy converters(WECs)suitable for offshore regions.Therefore,this work proposes a physical realization of a spring bistable mechanism(SBM).The spring bistable mechanism consists of a pair of pressure springs in series on each side and is integrated into the WEC with a power take-off(PTO)based on a mechanical motion rectifier.The system dynamic model in time domain is developed and validated by the bench test.The dynamic characteristics and performance of the integrated WEC in irregular waves are analyzed and compared for different WEC types,translational PTO damping,spring bistable stiffness and wave conditions.The passive control of the SBM is discussed to uncover the effect of the SBM on performance enhancement.The results suggest that the output power per displacement volume achieves 16.2W/m^(3)at the significant wave height of 0.1 m for the WaveBob type WEC,which is superior to that for the PowerBuoy type WEC.The output power is improved by a maximum ratio of 16.33%for the WaveBob type WEC due to the large hydrostatic stiffness of the spar and adjustment of natural frequency of the torus by the SBM in inter-well state.展开更多
文摘The forces of contraction and expansion about the seasons in tourism behave like an imaginary mechanical tourist spring.The article discusses tourist activities in Bulgaria from 2009 to 2020,predictions concerning Covid-19,and tendencies expected in the last quarter of 2021 till the end of 2022 on data published by the National Statistics Institute and Eurostat.The system’s dynamics observed before the pandemic crisis in tourism resembles the action of a mechanical spring that shrinks and extends,and we can empirically analyze the process of tourism activities.The study of this elasticity process of the system allows establishing a model with positive characteristics of the dynamics and further dealing with problems,better clarity in analysis and modeling of prognosis based on the potential of an imaginary mechanical spring concerning the possibility of the tourist destination.
基金Supported by National Natural Science Foundation of China(Grant No.51605006)Research Foundation of Key Laboratory of Manufacturing Systems and Advanced Technology of Guangxi Province,China(Grant No.17-259-05-013K)
文摘Being di erent from avoidance of singularity of closed-loop linkages, this paper employs the kinematic singularity to construct compliant mechanisms with expected nonlinear sti ness characteristics to enrich the methods of compliant mechanisms synthesis. The theory for generating kinetostatic nonlinear sti ness characteristic by the kinematic limb-singularity of a crank-slider linkage is developed. Based on the principle of virtual work, the kinetostatic model of the crank-linkage with springs is established. The influences of spring sti ness on the toque-position angle relation are analyzed. It indicates that corresponding spring sti ness may generate one of four types of nonlinear sti ness characteristics including the bi-stable, local negative-sti ness, zero-sti ness or positive-sti ness when the mechanism works around the kinematic limb-singularity position. Thus the compliant mechanism with an expected sti ness characteristic can be constructed by employing the pseudo rigid-body model of the mechanism whose joints or links are replaced by corresponding flexures. Finally, a tri-symmetrical constant-torque compliant mechanism is fabricated,where the curve of torque-position angle is obtained by an experimental testing. The measurement indicates that the compliant mechanism can generate a nearly constant-torque zone.
文摘Because the melting point of the alkalis is very high and the metal activity is strong, the common pressure sensor can＇t be used to measure pressure of liquid metal. In this paper, a differential transformer differential pressure sensor for measuring liquid alkalis pressure is designed, the working principle and specific design plan of the sensor are introduced, the standard current signal （ 4 -20 mA） or digital communication RS485 can be output according to the needs, and the functions of remote monitoring and data optimization can be realized through the LAN interface.
基金supported by the National Science Foundation of China(Grant No.81700884)Key Research and Development Program of Zhejiang Province(Grant No.2025C01132)+2 种基金General Research Project of Education Department of Zhejiang Province(Grant No.Y202352078)Zhejiang Province Public Welfare Technology Application(Grant No.LGF21H120005)Funding of Central Government Guiding Local Science and Technology Development(Grant No.2023ZY1061).
文摘Retinal surgery is one of the most delicate and complex operations,which is close to or even beyond the physiological limitation of the human hand.Robots have demonstrated the ability to filter hand tremors and motion scaling which has a promising output in microsurgery.Here,we present a novel soft micron accuracy robot(SMAR)for retinal surgery and achieve a more precise and safer operation.A remote center of motion(RCM)parallelogram structure with a double spring adaptive balancing mechanism is designed and optimized to achieve precise motion and safer operation.The deviation from the expected trajectory with manual operation and robot-assisted operation is 143.06μm±91.27μm vs 26.39μm±13.22μm,which has been significantly improved}.We evaluated the safety performance of SMAR in live animals.Furthermore,preliminary human clinical trials showed that the robot-assisted has less drift compared to the manual operation with 41.07μm±20.78μm vs 299.66μm±85.84μm.The visual acuity with LogMAR of cases showed higher improvement in the robot-assisted group preliminary,which for manual of 0.78±0.44 vs robot-assisted 1.24±0.70 with no statistically significant difference.This study provides promising options for robot-assisted with very experienced surgeons in the most challenging microsurgery.The system has the potential to effectively reduce the training curve of doctors and alleviate the shortage of ophthalmic surgeons,which is very important for rural areas and underdeveloped countries.
基金financially supported by the Canadian Space Agency(CSA)CMC Microsystems,the manager of the FABrIC project,which is funded by the Government of Canada,for providing CAD tools and test equipment that facilitated this research+2 种基金the 4D LABS core facility at Simon Fraser University,supported by the Canada Foundation for Innovation(CFI)British Columbia Knowledge Development Fund(BCKDF)Pacific Economic Development Canada(PacifiCan).
文摘The small dimensions of microfabricated devices present challenges in applications such as inertial sensing,where a larger proofmass is necessary for enhanced sensitivity.An effective approach to addressing the limitations of linear sensing is to use nonlinear mechanisms that adapt the device’s response according to different operating conditions.This paper introduces a new nonlinear spring mechanism for use in microsensors that harnesses the buckling phenomenon to achieve stiffness softening.The proposed mechanism utilizes a micro-arm to apply an eccentric axial load to an inclined beam,causing it to buckle in a controlled manner under a specified load.Once buckled,linear springs dominate the response of the system.We demonstrate that this method results in a smaller bias displacement compared to previously reported techniques based on snap-through behaviour,leading to potential reductions in device size and improvements in operational range.The behaviour is analytically modelled and verified through simulations.A prototype device was designed and microfabricated to experimentally validate the design principles.Compared to pre-curved nonlinear springs,the proposed design results in an 11-fold reduction in bias force,a 100-fold reduction in bias displacement,and a reduction in mechanical stiffness by a factor of 520.These results were verified through experiments conducted on a microfabricated accelerometer with an on-chip optical interferometer.Test results reveal an extended linear range of better than 150mg,a bias force of 0.3 mN,and a bias displacement of 10μm,measured with an integrated optical interferometer with a displacement noise floor of 40 pm/√ Hz p at 2 Hz and sensitivity of 194°=mg.
文摘Static balancing for a manipulator＇s weight is necessary in terms of energy saving and performance improvement. This paper proposes a method to design balancing devices for articulated robots in industry, based on robotic dynamics. Full design details for the balancing system using springs are presented from two aspects： One is the optimization for the position of the balancing system; the other is the design of the spring parameters. As examples, two feasible balancing devices are proposed, based on different robotic structures： The first solution consists of linkages and springs; the other consists of pulleys, cross mechanisms and （hydro-） pneumatic springs. Then the two solutions are compared. Pneumatic, hydro-pneumatic and mechanical springs are discussed and their parameters are decided according to the requirements of torque compensation. Numerical results show that with the proper design using the methodology presented in this paper, an articulated robot can be statically balanced perfectly in all configurations. This paper therefore provides a design method of the balancing system for other similar structures.
基金supported by National Natural Science Foundation of China(No.42461144208,No.42476226,No.42206227)Natural Science Foundation of Chongqing,China(No.CSTB2023NSCQMSX0432).
文摘Various bistable mechanisms have been extensively investigated in wave energy utilization.However,there is little application of their physical realization in two-body wave energy converters(WECs)suitable for offshore regions.Therefore,this work proposes a physical realization of a spring bistable mechanism(SBM).The spring bistable mechanism consists of a pair of pressure springs in series on each side and is integrated into the WEC with a power take-off(PTO)based on a mechanical motion rectifier.The system dynamic model in time domain is developed and validated by the bench test.The dynamic characteristics and performance of the integrated WEC in irregular waves are analyzed and compared for different WEC types,translational PTO damping,spring bistable stiffness and wave conditions.The passive control of the SBM is discussed to uncover the effect of the SBM on performance enhancement.The results suggest that the output power per displacement volume achieves 16.2W/m^(3)at the significant wave height of 0.1 m for the WaveBob type WEC,which is superior to that for the PowerBuoy type WEC.The output power is improved by a maximum ratio of 16.33%for the WaveBob type WEC due to the large hydrostatic stiffness of the spar and adjustment of natural frequency of the torus by the SBM in inter-well state.
