J052031 Development of the Variable Stiffness Control Device to Maintain the Flow Induced Vibration of an Elastically Supported Single Circular Cylinder

2013 ◽  
Vol 2013 (0) ◽  
pp. _J052031-1-_J052031-3
Author(s):  
Kazunori HOSOTANI ◽  
Takayuki ISHII
Author(s):  
Koki Yamada ◽  
Yuga Shigeyoshi ◽  
Shuangjing Chen ◽  
Yoshiki Nishi

Abstract Purpose This study elucidated the effect of an inclined spring arrangement on the flow-induced vibration of a circular cylinder to understand if the effect enhances the harnessing of the energy of fluid flows. Method An experiment was conducted on a circulating water channel. A circular cylinder was partially submerged. It was elastically supported by two springs whose longitudinal directions were varied. With the speed of the water flow varied, the vibrations of the circular cylinder were measured. The measured vibrations were interpreted by la linear dynamic model. Results and discussion In a few cases, a jump in response amplitudes from zero to the maximum was observed with the spring inclination at reduced velocities of 6 to 7, whereas gradually increasing response amplitudes were observed in other cases. The inclined spring arrangement achieved greater velocity amplitudes than in cases without spring inclination. A theoretical evaluation of the measured responses indicates that the effect of the inclined springs was caused by geometric nonlinearity; the effect would be more prominent by employing a longer moment lever.


2019 ◽  
Vol 1 (2) ◽  
pp. 80-97
Author(s):  
Jesus H Lugo

Safe interactions between humans and robots are needed in several industrial processes and service tasks. Compliance design and control of mechanisms is a way to increase safety. This article presents a compliant revolute joint mechanism using a biphasic media variable stiffness actuator. The actuator has a member configured to transmit motion that is connected to a fluidic circuit, into which a biphasic control fluid circulates. Stiffness is controlled by changing pressure of control fluid into distribution lines. A mathematical model of the actuator is presented, a model-based control method is implemented to track the desired position and stiffness, and equations relating to the dynamics of the mechanism are provided. Results from force loaded and unloaded simulations and experiments with a physical prototype are discussed. The additional information covers a detailed description of the system and its physical implementation.


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