Torque Measurement of 3-DOF Haptic Master Operated by Controllable Electrorheological Fluid
Abstract This work presents a torque measurement method of 3-degree-of-freedom (3-DOF) haptic master featuring controllable electrorheological (ER) fluid. In order to reflect the sense of an organ for a surgeon, the ER haptic master which can generate the repulsive torque of an organ is utilized as a remote controller for a surgery robot. Since accurate representation of organ feeling is essential for the success of the robot-assisted surgery, it is indispensable to develop a proper torque measurement method of 3-DOF ER haptic master. After describing the structural configuration of the haptic master, the torque models of ER spherical joint are mathematically derived based on the Bingham model of ER fluid. A new type of haptic device which has pitching, rolling, and yawing motions is then designed and manufactured using a spherical joint mechanism. Subsequently, the field-dependent parameters of the Bingham model are identified and generating repulsive torque according to applied electric field is measured. In addition, in order to verify the effectiveness of the proposed torque model, a comparative work between simulated and measured torques is undertaken.
Recent development of electro-responsive smart electrorheological fluids.
The characteristics of an electrorheological (ER) fluid, as a class of smart soft matter, can be actively and accurately tuned between a liquid- and a solid-like phase by the application of an electric field. ER materials used in ER fluids are electrically polarizable particles, which are attracting considerable attention in addition to further research. This perspective reports the latest ER materials along with their rheological understanding and provides a forward-looking summary of the potential future applications of ER technology.
Experimental evaluation of a new braking system for use in passive haptic displays
Passive haptic displays have several advantages when compared to active devices. Safety elements associated with active haptic displays may make them undesirable for certain applications. One method of actuation for passive haptic robots is through the use of brakes and clutches. Traditionally, friction brakes have undesirable behaviour, such as stiction and delay in response time due to mechanical motion. In this study a new brake concept is proposed. The performance of this brake is evaluated and quantified through a series of controlled experiments. Particular attention is given to the phenomenon of stiction in Delrin, dynamic response of the new brake, and effectiveness of feedback control for braking torque.