Vibration Isolation System Using Negative Stiffness

Effect of Nonlinearity Caused by Friction on a Negative Stiffness Control System

“…A vibration isolation system therefore should be capable to act as stiff and soft simultaneously. The vibration isolation system using negative stiffness technique can obtain these two conditions simultaneously [6]. The concept of negative stiffness technique to isolate vibration is presented in the following paragraphs.…”

“…To overcome the above-mentioned difficulties of conventional active vibration isolation system, the authors have proposed an active horizontal vibration isolation system using negative stiffness [6], [7]. Because series combination of negative and positive stiffnesses of equal absolute magnitude generates infinite stiffness, the vibration isolation system using negative stiffness connected with normal spring (positive stiffness) in series can attain zero compliance against direct disturbance.…”

“…Hoque et al [10] achieved a linearized zeropower control using a nonlinear compensator connected to the normal zero-power controller in parallel. Mizuno et al [6] used linear actuators that are voice coil motors (VCMs) to develop a vertical vibration isolation system. The authors have recently applied the concept of the negative stiffness technique mentioned above to a horizontal vibration isolation system, which is supported vertically and actuated by VCMs.…”

Active vibration isolation using negative stiffness and displacement cancellation controls: Comparison based on vibration isolation performance

“…A zero-power controlled magnetic suspension system was connected with a normal spring in series to isolate vibration because zero-power control magnetic suspension systems behave as if they have negative stiffness (Mizuno, Takasaki, Kishita, & Hirakawa, 2007). Mizuno et al acquired a vertical vibration isolation system using a linear actuator connected to a normal spring in series where the linear actuator was guided by a proper negative stiffness controller (Mizuno, Toumiya, & Takasaki, 2003); the characteristics of that system were further improved using a positive stiffness actuator instead of a normal spring (Shahadat, Mizuno, Ishino, & Takasaki, 2012). In this study, a proper stiffness controller is applied to acquire a negative stiffness control where the sign of controller parameters are selected so that a negative displacement takes place against a static direct disturbance.…”

Analysis of friction-induced oscillation in negative stiffness control system

“…The linear actuator with proper controller of negative stiffness also causes the accomplishment of negative stiffness. The series combination of the negative stiffness actuator and the normal spring of equal magnitude provide infinite stiffness in a vertical system [3]. The principle of such vibration isolation has been applied to a developed horizontal vibration isolation system where linear actuators are used to acquire both negative stiffness and positive stiffness [4].…”