“…Nowadays, apart from the Super Spring device, other absolute instruments use passive and active insulating methods (Hensley et al, ). In passive systems, the interferometer signal is corrected by using the acceleration measured by a seismometer (Le Gouët et al, ); in active devices the signal of the seismometer stabilizes the position of the reference mirror (Hauth et al, ; Hensley et al, ; Wu et al, ). Due to the stabilizing mechanical device, the active method is more complex to implement and would make field instruments heavier and more difficult to set up.…”
In a context of global change and increasing anthropic pressure on the environment, monitoring the Earth system and its evolution has become one of the key missions of geosciences. Geodesy is the geoscience that measures the geometric shape of the Earth, its orientation in space, and gravity field. Time‐variable gravity, because of its high accuracy, can be used to build an enhanced picture and understanding of the changing Earth. Ground‐based gravimetry can determine the change in gravity related to the Earth rotation fluctuation, to celestial body and Earth attractions, to the mass in the direct vicinity of the instruments, and to vertical displacement of the instrument itself on the ground. In this paper, we review the geophysical questions that can be addressed by ground gravimeters used to monitor time‐variable gravity. This is done in relation to the instrumental characteristics, noise sources, and good practices. We also discuss the next challenges to be met by ground gravimetry, the place that terrestrial gravimetry should hold in the Earth observation system, and perspectives and recommendations about the future of ground gravity instrumentation.
“…Nowadays, apart from the Super Spring device, other absolute instruments use passive and active insulating methods (Hensley et al, ). In passive systems, the interferometer signal is corrected by using the acceleration measured by a seismometer (Le Gouët et al, ); in active devices the signal of the seismometer stabilizes the position of the reference mirror (Hauth et al, ; Hensley et al, ; Wu et al, ). Due to the stabilizing mechanical device, the active method is more complex to implement and would make field instruments heavier and more difficult to set up.…”
In a context of global change and increasing anthropic pressure on the environment, monitoring the Earth system and its evolution has become one of the key missions of geosciences. Geodesy is the geoscience that measures the geometric shape of the Earth, its orientation in space, and gravity field. Time‐variable gravity, because of its high accuracy, can be used to build an enhanced picture and understanding of the changing Earth. Ground‐based gravimetry can determine the change in gravity related to the Earth rotation fluctuation, to celestial body and Earth attractions, to the mass in the direct vicinity of the instruments, and to vertical displacement of the instrument itself on the ground. In this paper, we review the geophysical questions that can be addressed by ground gravimeters used to monitor time‐variable gravity. This is done in relation to the instrumental characteristics, noise sources, and good practices. We also discuss the next challenges to be met by ground gravimetry, the place that terrestrial gravimetry should hold in the Earth observation system, and perspectives and recommendations about the future of ground gravity instrumentation.
“…According to Figure 3, wheel, motor, and vehicle body form a three degrees-of-freedom vibration reduction system, and the vertical vibration model of motor vibration-absorbing 1/4 suspension is as shown in Figure 4. 14,15 Figure 4.Vertical vibration model of motor vibration-absorbing 1/4 suspension.…”
Section: Design Of Motor Vibration-absorbing Systemmentioning
confidence: 99%
“…According to Figure 3, wheel, motor, and vehicle body form a three degrees-of-freedom vibration reduction system, and the vertical vibration model of motor vibration-absorbing 1/4 suspension is as shown in Figure 4. 14,15 In Figure 4, z 0 is the input of road excitation; z 1 , z 2 , z 3 are the wheel displacement, vehicle body displacement, motor displacement; m 1 , m 2 , m 3 are the wheel mass, 1/4 vehicle body mass, wheel-hub motor mass; k 1 , c 1 are the tire stiffness and damping; k 2 , c 2 are the stiffness and damping of suspension; k 3 , c 3 are the stiffness and damping of mounting element, respectively.…”
Section: Vertical Vibration Modeling Of Motor Vibration-absorbing 1/4mentioning
Based on the principle of multi-stage vibration isolation and active vibration absorption, a multi-stage passive vibration-isolating system and active motor vibration-absorbing system are designed for the electric wheel system of wheel-hub motor-driven electric vehicle, and the 1/4 suspension structural diagrams of the two vibration-isolating systems are drawn. Secondly, the corresponding multi-degrees-of-freedom vertical vibration model is established according to the different structural diagrams, and the dynamic differential equation of the multi-degrees-of-freedom vibration system is deduced. Then, by programming the MATLAB software is used to solve the acceleration of the vehicle body, the dynamic deflection of the suspension spring, and the amplitude, and the frequency characteristic curve of the relative dynamic load of the wheel of the 1/4 suspension system are drawn and the results are compared and analyzed. Finally, the ADAMS software is used for remodeling; the simulation experiment of ADAMS multi-body dynamics verified the correctness of the theoretical results of MATLAB software. The results show that the ADAMS simulation experiment results are consistent with the MATLAB theoretical results, and their correctness is verified. The vibration isolation effect of the active vibration-absorbing system is better and can improve the riding comfort and safety of the vehicle; hence it is worth popularizing and drawing.
“…Vibration, as a common phenomenon in the nature, often undermines the stability and reliability of various engineering instruments or equipment. Hence, vibration isolation is indispensable for these instruments and equipment [53,54]. In most engineering applications, attention has to be mainly paid to the vibration noise at 10-100 Hz or higher frequency, e.g., various means of transport and engines.…”
An atomic interference gravimeter (AIG) is of great value in underwater aided navigation, but one of the constraints on its accuracy is vibration noise. For this reason, technology must be developed for its vibration isolation. Up to now, three methods have mainly been employed to suppress the vibration noise of an AIG, including passive vibration isolation, active vibration isolation and vibration compensation. This paper presents a study on how vibration noise affects the measurement of an AIG, a review of the research findings regarding the reduction of its vibration, and the prospective development of vibration isolation technology for an AIG. Along with the development of small and movable AIGs, vibration isolation technology will be better adapted to the challenging environment and be strongly resistant to disturbance in the future.
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