This paper proposes a new prosthesis operated in two different modes; the semi-active and active modes. The semi-active mode is achieved from a flow mode magneto-rheological (MR) damper, while the active mode is obtained from an electronically commutated (EC) motor. The knee joint part of the above knee prosthesis is equipped with the MR damper and EC motor. The MR damper generates reaction force by controlling the field-dependent yield stress of the MR fluid, while the EC motor actively controls the knee joint angle during gait cycle. In this work, the MR damper is designed as a two-end type flow mode mechanism without air chamber for compact size. On other hand, in order to predict desired knee joint angle to be controlled by EC motor, a polynomial prediction function using a statistical method is used. A nonlinear proportionalderivative controller integrated with the computed torque method is then designed and applied to both MR damper and EC motor to control the knee joint angle. It is demonstrated that the desired knee joint angle is well achieved in different walking velocities on the ground ground.

This article presents vibration control performances of a semi-active railway vehicle suspension system using a magnetorheological damper tested on the roller rig. In order to evaluate control performances, a mathematical railway vehicle model with 15 degrees of freedom is first derived to represent the lateral, yaw and roll motions of the car body, bogie frame, and wheel set, respectively. Based on the formulated model, the design parameters of magneto-rheological damper are determined to undertake a compatible comparison with dynamic performances of conventional (existing) passive railway vehicle suspension system. The designed magneto-rheological damper is manufactured and its field-dependent damping force characteristics are experimentally evaluated. Subsequently, in order to enhance the ride quality of a railway vehicle suspension equipped with magneto-rheological damper, a skyhook controller associated with an extended Kalman filter is designed in a state space representation. The railway suspension system incorporated with the car body and two bogies is then experimentally set up on the roller rig in order to evaluate the ride quality. It is demonstrated from experimental realization of the controller that the ride quality of the suspension system with magneto-rheological damper can be significantly enhanced compared with the existing passive suspension system.

In this study, we developed a novel four-degrees-of-freedom haptic master using controllable magnetorheological (MR) fluid. We also integrated the haptic master with a vision device with image processing for robot-assisted minimally invasive surgery (RMIS). The proposed master can be used in RMIS as a haptic interface to provide the surgeon with a sense of touch by using both kinetic and kinesthetic information. The slave robot, which is manipulated with a proportional-integrative-derivative controller, uses a force sensor to obtain the desired forces from tissue contact, and these desired repulsive forces are then embodied through the MR haptic master. To verify the effectiveness of the haptic master, the desired force and actual force are compared in the time domain. In addition, a visual feedback system is implemented in the RMIS experiment to distinguish between the tumor and organ more clearly and provide better visibility to the operator. The hue-saturation-value color space is adopted for the image processing since it is often more intuitive than other color spaces. The image processing and haptic feedback are realized on surgery performance. In this work, tumor-cutting experiments are conducted under four different operating conditions: haptic feedback on, haptic feedback off, image processing on, and image processing off. The experimental realization shows that the performance index, which is a function of pixels, is different in the four operating conditions.

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