Sang-Min Choi

The design of a piezostack-based active mount and application to a vibration control system

In this work, a new active mount featuring piezostack actuators and a rubber element is proposed and applied to a vibration control system. After describing the configuration and operating principle of the proposed mount, an appropriate rubber element and appropriate piezostacks are designed and manufactured. Subsequently, the dynamic characteristics of the piezostacks and the rubber element are experimentally identified. A vibration control system with a supported mass of 50 kg is then constructed, and its governing equations of motion are derived. In order to actively attenuate the vibration transmitted from the base excitation, a robust sliding mode controller is formulated with consideration of parameter uncertainties. The controller is then experimentally realized and vibration control performances (acceleration and transmitted force) of the proposed mount are evaluated in both time and frequency domains.

A new adaptive hybrid controller for vibration control of a vehicle seat suspension featuring MR damper

This paper presents a new hybrid controller which is a combination of three control schemes: fuzzy neural control, PI control and sliding mode control. The interval type 2 fuzzy model featuring updated rules via online is used in this study and in order to support the fuzzy model, a granular clustering method is applied to find groups of data related to the initial fuzzy rule. Then the output for fuzzy model is used for the PI-sliding mode controller. The combination of PI and sliding mode controls is carried out by H-infinity technique method which is rely on the modified Riccati-like equation. After developing the mathematical model, the proposed controller is applied to vibration control of a vehicle seat suspension featuring magneto-rheological (MR) damper. In order to demonstrate the effectiveness of the proposed controller, two different excitations of bump and random signals are adopted and corresponding vibration control performances are evaluated. It is demonstrated through both simulation and experiment that the proposed controller can provide much better than vibration control performance compared with the conventional controllers showing more robust stability.

A new adaptive sliding mode control for Macpherson strut suspension system with magneto-rheological damper

This work proposes a new adaptive sliding mode controller to enhance ride comfort and steering stability of automobile associated with a semi-active magneto-rheological damper. In this study, a Macpherson strut type suspension system which is widely used in light vehicles is considered. The dynamic model of the Macpherson strut with magneto-rheological damper is obtained and the governing equations are then formulated using kinematic properties of the suspension system following Lagrange’s formulation. In the formulation of the model, both the rotation of the wheel assembly and the lateral stiffness of the tire are considered to represent the nonlinear characteristic of Macpherson type suspension system. Subsequently, in order to effectively reduce unwanted vibrations, a new adaptive sliding mode controller is designed by adopting moving sliding surface instead of conventional fixed sliding surface. In order to demonstrate the effectiveness of the proposed controller, a cylindrical magneto-rheological damper is designed and manufactured on the basis of practical application conditions such as required damping force. Then, ride comfort, suspension travel, and road handling are evaluated and some benefits of the proposed controller such as enhanced ride comfort are evaluated.

Design and control of a hybrid mount featuring a magnetorheological fluid and a piezostack

In this study, a hybrid mount featuring a magnetorheological (MR) fluid and a piezostack is devised to reduce vibrations occuring in dynamic systems which are operated in a wide frequency range. An MR fluid is adopted to improve isolation performance at resonant low frequencies, whereas a piezostack actuator is adopted for performance improvement at non-resonant high frequencies. As a first step, a passive rubber part is manufactured and its dynamic characteristics are experimentally evaluated. By adopting the MR fluid and the piezostack, semi-active and active actuating mechanisms are devised and their mathematical models are derived. In particular, the magnetic circuit for MR operation is optimally designed via finite element analysis. After evaluating the dynamic characteristics of the manufactured MR device and inertial piezostack actuator, the proposed hybrid mount is then established by integrating them with the rubber part. Subsequently, a vibration control system is constructed using the proposed hybrid mount, and a sliding mode controller (SMC) is designed to attenuate the vibrations transmitted from the base excitation. Control performances of the proposed mount are experimentally evaluated in time and frequency domains.

A piezostack-based active mount for broadband frequency vibration control: experimental validation

This paper presents an experimental investigation on vibration control using an active mount activated by piezostack actuators. After describing the schematic configuration and operational principle of the proposed active mount, dynamic characteristics of the rubber element and the piezostack are experimentally identified. An active mount is then manufactured using a rubber element and two piezostack elements. Prior to validating vibration control of the proposed active mount, fundamental characteristics such as resonant frequency, deflection at rated load, strength, shock and fatigue characteristics are experimentally investigated. A two-degree-of-freedom control system in which an active mount is installed with a supported mass of 100 kg is established for evaluating vibration control performance. In order to actively attenuate the vibration transmitted from the base excitation (50–1000 Hz), a negative velocity feedback controller is experimentally realized. Control responses such as mass acceleration are evaluated in both frequency and time domains.

The Numerical Analysis of Channel Flows of ER Fluida

A numerical analysis is performed on the flow characteristics of an electrorheological (ER) fluid when fully developed ER fluid flow in a channel is instantly subjected to electric fields. The Bingham plastic model is used to describe the ER fluid behavior. The flow field is assumed to be incompressible and isotropic. The SIMPLER algorithm with staggered grid system is employed to solve the momentum and continuity equations governing the steady state, laminar flow. The effects of electric field intensity and upper wall velocity changes on velocity profiles are investigated.

An adaptive fuzzy sliding mode control of magneto-rheological seat suspension with human body model

This article presents the control performances of a vehicle seat suspension system equipped with magneto-rheological dampers using a new adaptive fuzzy sliding mode controller. A magneto-rheological damper is designed by applying the Bingham model incorporating with the field-dependent rheological properties of magneto-rheological fluid. On the other hand, a seat suspension model is established by integrating with a 4-degree-of-freedom human body model. Then, the governing equations are then derived considering the vertical motion of the seat. Subsequently, an adaptive fuzzy controller is formulated by considering the acceleration of the seat. This controller is combined with the sliding mode controller to ensure the robustness against model uncertainty and external disturbances. The controller is then evaluated through experiment. It is demonstrated that the proposed seat suspension system realized by the proposed adaptive fuzzy sliding mode controller can provide very effective ride comfort performances by reducing vertical acceleration under regular bump, random signal, and sinusoidal excitations.

A Study on Development of an Active Hybrid Mount for Naval Shipboard Equipment

ABSTRACT A hybrid mount for shipboard machinery installed on naval ships was developed. The mount is combined with a rubber mount and a piezostack actuator. The rubber mount is one of the most popular and effective passive mounts to have been applied to various vibration systems to date. The piezostack actuator is featured by a fast response time, small displacement and low power consumption. Through a series of experimental tests conducted in accordance with MIL-M-17185A(SHIPS), MIL-M-17508F(SH), and MIL-S-901D which are US military specifications related to the performance requirements of the mount, it has been confirmed that the hybrid mount shows more effective performance for use in naval ships. * 1. 서 론 기술의 진보와 함께 항공기, 선박, 자동차 등 수송기계시스템에 탑재되는 장비의 성능사양 뿐만 아니라 소음, 진동 및 충격 등 특수성능 사양도 강화되고 있다. 특히 잠수함과 같은 해군 함정의 경우 생존성 분야 연구의 증가와 함께 고정도 스텔스 성능확보 및 탐지에 대한 사양이 강화되고 있다. 함정에 탑재되고 있는 각종 기계/전자 장비들을 살펴보면, 장비 하부에 다양한 형태의 마운트가 설치되어 있는 것을 알 수 있다. 이러한 마운트 설치의 목적†교신저자; 정회원, 한국기계연구원E-mail : sjmoon@kimm.re.krTel : (042)868-7428, Fax : (042)868-7418* 한국기계연구원** 정회원, 인하대학교*** 국방과학연구소**** 국방과학연구소 민군겸용센터은 첫째 탑재장비에서 발생하는 진동 및 소음이 하부 구조물로 전달되는 것을 차단함으로서 함내 거주성을 향상시키고, 적으로부터 탐지되는 확률을 저감시키는 데 있다. 둘째는 적으로부터의 공격 등 외부 충격으로부터 장비를 보호함으로서 함정의 작전능력을 항시 유지하는 데 있다.현재 사용되고 있는 함정 탑재장비용 마운트는 대부분 수동형 마운트로서 고무 또는 와이어의 탄성특성을 이용하는 탄성 마운트이다. 이러한 탄성 마운트는 작은 감쇠특성을 보유하고 있으며, 고주파수의 비공진 주파수 대역에서는 우수한 진동절연 성능을 보이고 있다. 그러나 탑재장비가 자체 기진력이 있는 경우에는 탑재장비의 기진력으로 인하여 특정 주파수에서 진동이 현저하게 나타날 수 있으며, 수동형 마운트로서는 만족스러운 결과를 얻기 어렵다. 이러한 경우에는 능동형 마운트를 고려할 수 있으나, 함정과 같이 입력되는 진동이 큰 경우에는 큰 제어력이 필요하게 되며, 일반적으로 수동형

Active Vibration Control of Automotive Engine Mount Using MR Fluid and Piezostack

This paper presents vibration control of an active hybrid engine mount featuring a magneto-rheological(MR) fluid and a piezostack actuator. The MR fluid is adopted to improve isolation performance at resonant frequencies, while the piezostack actuator is adopted for performance improvement at non-resonant frequencies, especially at high frequencies. Based on some particular practical requirements of engine mounts, the proposed mount is designed and manufactured. The characteristics of rubber element, piezostack actuator and MR fluid are verified for system analysis and controller synthesis. The dynamic model of the proposed mount with a supported mass (engine) is established. In this work, a sliding mode controller is synthesized for the mount system to reduce vibrations transmitted from the engine in a wide frequency range. Computer simulations are performed to evaluate control performances of the proposed active engine mount in time and frequency domains.

Active Vibration Control Using Piezostack Based Mount

This paper presents active vibration control performance of a hybrid mount. The proposed hybrid mount is devised by adopting both piezostack as an active actuator and rubber as a passive element. After experimentally identifying actuating force characteristics of the piezostack and dynamic characteristics of the rubber, the hybrid mount was designed and manufactured. Subsequently, a vibration control system with a specific mass loading is constructed, and its governing equations of motion are derived. In order to actively attenuate vibration transmitted from the base, a feedforward controller is formulated and experimentally realized. Vibration control responses are then evaluated in time and frequency domains.