Category: Publications

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.

In this paper, a novel structure of four degrees of freedom (4DOF) hybrid magnetic bearing is proposed for double gimbal magnetically suspended control momentum gyro (DGMSCMG). It includes two active parts and one passive part, and every active part has eight stator magnetic poles around the circumference in X and Y directions, which are divided into upper and lower layers. The passive part has two whole magnetic rings, which is located in the middle of this 4DOF hybrid magnetic bearing. The radial active force is analyzed by equivalent magnetic circuit method (EMCM) and the axial resilience force is analyzed by the infinitesimal method based on the end magnetic flux. Meanwhile, 3-D finite element model of the 4DOF hybrid magnetic bearing is establish with ANSYS software, and the radial displacement versus radial force, the current versus radial force, and the axial displacement versus axial resilience force characteristics are analyzed compared with the EMCM. Furthermore, the 10Nms DGMSCMG prototype with proposed 4DOF hybrid magnetic bearing is manufactured, and the experiments of the radial active force test and the axial resilience force test are carried out. Experimental results show that the presented 4DOF hybrid magnetic bearing has good force performance and verify the correctness of the theoretical analysis.