This study presents force feedback control performance of a spherical haptic device featuring an electrorheological (ER) fluid that can be used for minimally invasive surgery (MIS). As a first step, a spherical ER joint composed of rotational and stationary electrodes is designed and optimized based on mathematical torque modeling. The active force produced in MIS is generally small, even though the passive force is large. In order to meet this agreement, both clutch and brake mechanism are adopted for the ER joint. In this operation, the active (small) force feedback by the rotational electrodes and/or semi-active (large) force feedback are achieved by the stationary electrode. Subsequently, the master device is manufactured by integration of the spherical ER joint with AC motor. In order to achieve desired force trajectories, a sliding mode controller, which is robust to uncertainty, is formulated by considering mechanical friction and hysteretic behavior of the ER fluid as uncertainty. The controller is then experimentally realized. Tracking control performances for various force trajectories are presented in time domain.
This research work presents a surface-based virtual dental surgical simulator in which dentists can perform dental procedures using various cutters with realistic feelings of touch. Generating realistic smooth tactile feelings during drilling, grinding, or scrubbing is a critical issue in triangular sculpting simulators. Therefore, a stable haptic rendering algorithm is required to generate realistic touch feeling. In this simulator, the force feedback is realized using a spring damper force model and a force filter is proposed to make the force feedback smooth. Fast and efficient collision detection is used using vertex deformation technique for the sculpting process. In addition, the simulator is not designed for the one specific surface-based tooth model but rather the sculpting simulation can be carried out on any scanned model from a commercial 3D dental scanner.
848surface. Experiments were carried out using a Phantom Omni TM haptic device; these experiments involved the three-dimensional cutting of a tooth model using a proposed force filtering method. The experiment operations verify that the force stability can be easily maintained under the specified operation criteria.
This paper presents dynamic modeling and control analysis of a military vehicle suspension featuring MR valve structure. Firstly, the dynamic model of the suspension system which is included gas spring, MR valve and gas chamber is established with respect to the disturbance. Secondly, the friction model of the suspension system is derived by considering experiment result of the MR suspension system. And then, response characteristics of the damping force with respect to the magnetic field and friction force with the proposed friction model are provided to show the feasibility of practical application. In addition, control performance of the proposed MR suspension system is evaluated with quarter vehicle.
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