Month: December 2016

This paper has presented a novel diaphragm-type fiber Bragg grating (FBG) vibration sensor with a small mass and an excellent sensitivity through the use of the transverse property of a tightly suspended optical fiber with two fixed ends. Two suspended optical fibers that were embedded with an FBG element each, have been arranged symmetrically along the both sides of the diaphragm in a parallel manner, and their middle points were connected with the two surfaces of the mass by rigid thin rods to sense vibration. The theoretical model of the presented sensor has been derived, and its sensing characteristics have been analyzed by numerical simulation to determine the physical parameters. Experiments have been conducted to show that its sensitivity is 31.25 pm/g within a working bandwidth range of 10~150 Hz. The linearity and relative sensitivity errors are respectively 2.21% and ±10%. The experimental resonant frequency of 300 Hz is consistent with the theoretical value, which has verified the effectiveness of the proposed theoretical model. The temperature response of this sensor has decreased to 1.32 pm/℃ in the range of 30~90 ℃ after implementing the temperature compensation. Compared with the existing diaphragm-enabled FBG vibration sensors, the proposed sensor enables to support the easy implementation of distributed measurement, and the small mass allows for detection on mass-sensitive structures.

Robot-assisted systems have been developed for minimally invasive surgical procedures, which bring tremendous benefits for patients, such as less trauma, less bleeding, and shorter recovery time. Among the contemporary surgical robotic manipulators, flexible serpentine manipulator shows great advantages on operating with complicated nonlinear anatomical constraints, and it can reach deep occluded surgical targets without colliding in a critical anatomical environment. In surgical robotic operation, less spatial sweeping area from the flexible manipulator in motions is desired to induce the minimal surgical complications. The goal of our research is to reduce unnecessary sweeping motion of the flexible surgical manipulator in operations, and to obtain safer and more reliable reference trajectories. A novel 3-D neural dynamic model is proposed and expected to obtain the safety-enhanced trajectory in workspace with the consideration of minimum sweeping area. In this model, the neural stimulation propagates from the start state to the whole network through the connective weight of manipulator’s sweeping area. According to the results of comparative studies with commonly used planning algorithms in various simulation scenarios, the proposed planning algorithm is validated in terms of effectiveness and safety. Ultimately, the experiments on phantoms and preclinical cadaveric human head show the feasibility of the proposed safety-enhanced planning algorithm.

In this paper, the fault diagnosis (FD) problem in image-based visual servoing with eye-in-hand configurations is investigated. The potential failures are detected and isolated based on approximating parameters related. First, the failure scenarios of the visual servoing systems are reviewed and classified into the actuator and sensor faults. Second, a residual generator is proposed to detect the failure occurrences, based on the Kalman filter. Third, a decision table is proposed to isolate the fault type. Finally, simulation and experimental results are given to validate the efficacy and the efficiency of the proposed FD strategies.