In this paper, a new magneto-rheological MR) fluid damper is proposed to achieve lower limb exoskeleton of the rehabilitation device. This is achieved by designing the piston configuration as both a square geometry and a circular geometry. By doing this, controllability of the both vibration and moment in the horizontal axis can be obtained. In the design process, two operation modes of MR fluid including flow mode and shear mode are used and the principal design parameters of the square piston are optimized to have low limb exoskeleton as possible under imposed design constraints such as size. This principle is also applied for the circular piston. In addition, the configuration parameters of the design are obtained by optimization using a commercial software as ANSYS ADPL. It is shown through computer simulations that the requirements of the force associated with the limb exoskeleton are successful achieved.
In this paper, a new skin tissue which can emulate the stiffness of several organs of human being is proposed and analyzed utilizing a magneto-rheological (MR) fluid. It is called MR skin. The proposed skin can be applied to the robot assisted surgery manipulated by the haptic devices as a controllable tactile sensor. In order to formulate the device, the valve networks are embedded inside the structure of the master actuator. These valves use the flow mode and shear mode of MR fluid for the pressure control. The deformation equation of the MR skin is derived and the external force contacting to the MR skin is also analyzed. After formulating, the proposed tactile display is optimized by using the finite element method. In the optimization process, many different forces are applied to view different deformation of MR skin with different pressures. It is shown via the optimization that the results satisfy the initial requirements of the design. This result directly indicates that the proposed MR skin structure is feasible in the manufacturing sense and applicable to haptic devices for robotic surgery.
In this study, a new pressure seal, which can adjust the magnitude of the yield stress of the chamber containing a magnetorheological (MR) fluid, is investigated. The proposed seal can maintain the required pressure during the rotation of the shaft which may vary due to the friction. This design is based on the field-dependent special characteristics of MR fluid. Specifically, the inherent property of MR fluid changing from the liquid phase to semi-solid phase by applying the magnitude is utilized to achieve this goal. Owing to the semi-solid property of MR fluid under the magnetic field, MR fluid can replace the role of silicon materials in designing seal structure. Due to the high sealing provision, the proposed seal can be applicable to pressure locking, dust- and water-proof, and mating two different pieces. The maximal pressure which can be handled by the proposed is derived and analyzed in each case. The behaviors of fluid inside the housing is simulated and observed through the commercial software. The optimization of seal dimensions are then calculated without the pressure loss in design process.
In this study, a semi-active magnetorheological (MR) damper for the main landing gear suspension system of the aircraft is proposed. MR damper is designed with two magnetic cores to control the effective damping force and also with annular bypass for fast expanding speed considering the characteristics of the aircraft landing. A controllable yield force of the MR fluid with respect to the input current is analyzed as a first step, and a vertical landing model with MR damper is considered to evaluate aircraft landing efficiency. In this work, a sky-ground controller is designed and applied to MR damper to maximize the landing efficiency of the drop simulation. The damping force of MR damper is controlled by the input current calculated by the proper choice of the sky hook gain and ground hook gain, respectively. It is demonstrated through the comparative work between the passive and proposed semi-active MR damper based landing gear that the landing gear efficiency of the passive damper can be enhanced a lot showing the efficiency above 90%.
Airplane landing gears are subjected to a wide range of excitation conditions due to variations in sink speed and road condition. An existing passive type damper for the landing gear is hard to satisfy these various conditions. A semi-active type magnetorheological (MR) damper is one of attractive solutions to resolve this problem. This work presents design and analysis of MR damper applicable to the landing gear system. MR damper is designed based on the required damping force and packaging constraints. Especially, the geometry of the magnetic core is optimized in terms of magnetic intensity at magnetic poles to achieve uniform magnetic intensity under the packaging constraints. The effectiveness of the proposed MR damper is given by presenting the field-dependent damping force and the efficiency.
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