关键词： Mobile robots   dynamics   adaptive control   nonholonomic   visual servoing  

摘要： The visual servoing feedback torque stabilization controller of a nonholonomic mobile robot is developed in this paper. Firstly, a camera-object visual servoing kinematic model is introduced and a kinematic stabilizing controller is designed for the kinematic model. Then, an adaptive torque stabilizing controller is proposed in the presence of parametric uncertainties associated with the mechanical dynamics and the camera system. The stability of the proposed control system is rigorously proved through the Lyapunov method. Simulation results are provided to illustrate the performance of the control law.

关键词： Tethered space robot   Dynamics modelling   Coordinated control   Optimal control  

摘要： Tethered space robots use tethers to replace rigid arms and have more flexibility than a traditional space robot, which gives it wide application prospect in future on-orbit servicing missions. Before carrying out elaborate manipulations, tethered operation robots need to approach the target. In order to save fuel in the approaching phase, various coordinated control methods that employ tethers and thrusters together are investigated in the literature. However, the increasing mass of the tether and the distributed force acting on the tether will affect the position and attitude of the robot, which is neglected in previous studies and can degrade the performance of the control system. Here, in order to involve these factors, coupled dynamics and coordinated control theories are combined and applied. Firstly, a coupling dynamics model for the tethered space robot system is built based on the Hamilton principle and the linear assumption. Then, based on the dynamics model, we design an optimal coordinated controller which can minimize the fuel consumption by using the hp-adaptive pseudospectral method and the classical PD controller. Finally, the advantages of the proposed method and the performance of the designed controller are validated by the numerical simulation. (C) 2014 Elsevier Masson SAS. All rights reserved.

关键词： Minimally invasive surgery   Laparoscopy   Pediatrics   Robotic surgery   Da Vinci surgery   Ureteropelvic junction obstruction  

摘要： Ureteropelvic junction (UPJ) obstruction is a common anomaly, and presents clinically in all pediatric age groups. The past 3 decades have witnessed an evolution in the surgical correction of UPJ obstruction on several fronts, with open surgical techniques yielding way to endoscopic, laparoscopic, and robotic-assisted approaches. Robotic-assisted surgery has several advantages in complex laparoscopic reconstructive procedures such as pyeloplasty. Comparative studies of laparoscopic and robot-assisted repairs have demonstrated similar success rates. Laparoscopic pyeloplasty is here to stay because of its advantages of safety, efficacy, decreased morbidity, reduced hospital stay, and, perhaps most importantly, cost-effectiveness.

关键词： Robotics  

摘要： The Journal of Mechanisms and Robotics was established five years ago with the first volume being published in February 2009. We owe a profound debt of gratitude to Professor McCarthy, the founding editor, for his bold vision for the journal and for creating a venue for archival publications dedicated to mechanisms and robotics. During his tenure, the journal grew rapidly to critical mass with approximately 200 submissions annually, averaging an acceptance rate of around 25%, and publishing four issues per year. The journal continues to publish research contributions to the fundamental theory, algorithms, design, manufacture, and experimental validation for mechanisms and robots. The current scope of the journal includes topics in theoretical and applied kinematics, mechanism synthesis and design, analysis and design of robot manipulators, hands, and legs, soft robotics, compliant mechanisms, origami and folded robots, printed robots, and haptics devices. The journal is also...

关键词： kinematics   Medical   robotics   Physical Education   Safes   United States  

摘要： Objective: Endovascular robotics systems, now approved for clinical use in the United States and Europe, are seeing rapid growth in interest. Determining who has sufficient expertise for safe and effective clinical use remains elusive. Our aim was to analyze performance on a robotic platform to determine what defines an expert user. Methods: During three sessions, 21 subjects with a range of endovascular expertise and endovascular robotic experience (novices < 2 hours to moderate-extensive experience with > 20 hours) performed four tasks on a training model. All participants completed a 2-hour training session on the robot by a certified instructor. Completion times, global rating scores, and motion metrics were collected to assess performance. Electromagnetic tracking was used to capture and to analyze catheter tip motion. Motion analysis was based on derivations of speed and position including spectral arc length and total number of submovements (inversely proportional to proficiency of motion) and duration of submovements (directly proportional to proficiency). Results: Ninety-eight percent of competent subjects successfully completed the tasks within the given time, whereas 91% of noncompetent subjects were successful. There was no significant difference in completion times between competent and noncompetent users except for the posterior branch (151 s: 105 s;P = .01). The competent users had more efficient motion as evidenced by statistically significant differences in the metrics of motion analysis. Users with > 20 hours of experience performed significantly better than those newer to the system, independent of prior endovascular experience. Conclusions: This study demonstrates that motion-based metrics can differentiate novice from trained users of flexible robotics systems for basic endovascular tasks. Efficiency of catheter movement, consistency of performance, and learning curves may help identify users who are sufficiently trained for safe clinical use of

关键词： hydrogels   tough   LCST   actuator   robotics  

摘要： Tough Al-alginate/poly(N-isopropylacrylamide) (PNIPAM) hydrogel has been synthesized by introducing an interpenetrating network with hybrid physically cross-linked alginate and chemically cross-linked PNIPAM. Varying the concentration of AlCl3 regulates the mechanical properties of the tough hydrogel and tunes its lower critical solution temperature (LCST) as well. The tough Al-alginate/PNIPAM exhibits 6.3 +/- 0.3 MPa of compressive stress and 9.95 of uniaxial stretch. Tunability of LCST is also achieved in a wide range within 22.5-32 degrees C. A bending beam actuator and a four-arm gripper made of bilayer (Na-alginate/PNIPAM)/(Al-alginate/PNIPAM) hydrogel as prototype of all-hydrogel soft robotics are demonstrated. A finite element (FE) simulation model is developed to simulate the deformation of the soft robotics. The FE simulation not only reproduces the deformation process of performed experiments but also predicts more complicated devices that can be explored in the future. This work broadens the application of temperature-responsive PNIPAM-based hydrogels.

摘要： 3166-Pos

关键词： Motion planning  

摘要： For solving serial manipulators path-planning when grabbing target in obstacle workspace, a solution of fuzzy control ant colony algorithm is presented. We transform serial manipulators pathplanning into the multidimensional function maximum problem, at the same time, the independent variables of multidimensional function are gridded. Fuzzy control ant colony algorithm makes a 'path-planning' on the gridded multidimensional domain of the function. And we also improve the conventional Ant Colony Algorithm with fuzzy control intelligent pheromone updating method, it successfully increases convergence, accuracy and heuristic of the algorithm. The experiment of PUMA560 grabbing target in obstacle workspace is solved satisfactorily by the fuzzy control ant colony algorithm, and in laboratory, 6 freedom manipulator is also made an obstacle avoidance grabbing target experiment, it has a good precision and optimal path-planning when grabbing target, and it will be more accurate with increased iterations. Therefore, Practice has proved that the feasible method of solving robotics multi-freedom manipulators grabbing target problem in obstacle workspace is presented by this paper. Copyright © 2015 American Scientific Publishers All rights reserved.

关键词： *ROBOTICS   *MACHINE theory   *AUTOMATION   *HAPTIC devices   *ROBOT dynamics