Construction and Layout of Coordinated Multirobots System Based on Parallel Thought

Aiming at the problems that are the construction and the layout optimization of the coordinated multirobots system, the concept of an equivalent parallel robot (EPR) is proposed based on parallel thought in this paper. That is, each robot is regarded as a branched chain of the EPR in coordination. Thus, it can be converted into the problem for the type synthesis and the layout of the parallel robot. Firstly, the definition of robotic characteristic (C) set and the corresponding operational rule are given. Then, the minimum occupied area, cycle time, and condition number are used as the optimized objectives. The weight ratio is used to express the importance of the three objectives to meet the requirements of different scenes. Afterwards, based on the theory of C set, the three translational (3T) operational requirements that can be extended to other degree of freedom (DOF) are analyzed. Finally, the feasibility of the proposed methods is verified by the DOF analysis and simulation experiment. Moreover, the multiobjective layout problem is optimized based on the artificial bee colony (ABC) algorithm. The results show that the constructed robot combinations and the layout optimization method are satisfactory

TIME DELAY CONTROL OF CABLE-DRIVEN MANIPULATORS WITH ARTIFICIAL BEE COLONY ALGORITHM

Cable-driven manipulators (CDM) are widely-used for their unique advantages such as light weight, low moving mass, high payload-to-weight ratio and large reachable workspace. However, their complex dynamic character and low stiffness with flexible joints make the control designing much more difficult than the traditional robot manipulators. In this paper, time delay control (TDC) which combines PID control method and time delay estimation (TDE) technology will be investigated to build a model-free controller for CDM. PID parameters are reduced dramatically as TDE compensates for a large proportion of unknown dynamics. To handle the problem in tuning parameters of this controller, artificial bee colony (ABC) algorithm is utilized to obtain optimal parameters of PID. Finally, simulations are conducted to verify the effectiveness of the propose controller and the tuning method.The accepted manuscript in pdf format is listed with the files at the bottom of this page. The presentation of the authors' names and (or) special characters in the title of the manuscript may differ slightly between what is listed on this page and what is listed in the pdf file of the accepted manuscript; that in the pdf file of the accepted manuscript is what was submitted by the author

Nonsingular terminal sliding mode control of underwater remotely operated vehicles

This study investigates the nonsingular terminal sliding mode control (NTSMC) method for the 4-DOF (degrees of freedom) trajectory tracking control problem of underwater remotely operated vehicles (ROVs) in the presence of parametric uncertainties and external disturbances. Two new control algorithms have been developed for ROVs. The first one, combining a nonsingular sliding surface with a fast-TSM-type reaching law, is nonsingular and chattering-free. The second one, introducing adaptive methodology to compensate for the lumped uncertainties, is an improved version of the first algorithm and can be called adaptive NTSMC (ANTSMC). The application of adaptive methodology effectively eases the chattering problem. Meanwhile, it also provides better robustness and higher tracking precision compared with the first algorithm. A corresponding stability analysis is presented using Lyapunov stability theory, and some comparative numerical simulation results are presented to show the effectiveness of the proposed approaches.The accepted manuscript in pdf format is listed with the files at the bottom of this page. The presentation of the authors' names and (or) special characters in the title of the manuscript may differ slightly between what is listed on this page and what is listed in the pdf file of the accepted manuscript; that in the pdf file of the accepted manuscript is what was submitted by the author

KINEMATIC ANALYSIS OF A NEWLY DESIGNED CABLE-DRIVEN MANIPULATOR

In this paper, the configurations of cable routings for cable-driven manipulator are introduced, and the impact of motion coupling caused by cable transmission routing of 2n type cable-driven manipulator is analyzed in details. Based on different configurations of cable routings, the relationship between variation of joints angles and the geometrical sizes of guide pulleys is established with the representation by a matrix for coupled motion. Meanwhile, based on the effects of the motion coupling of cable-driven manipulator, we proposed the condition for the invariance of orientation, which can be achieved by the constraint of the geometrical sizes of guide pulleys and driven wheels. In addition, in order to identify the correctness of analysis for coupled motion, a 3-DOFs planer cable-driven manipulator prototyping model is constructed, and the kinematics and trajectory planning has been solved. Finally, the relationship among actuator space, joint space, and Cartesian space, including the mapping of the motion coupling is experimentally validated. And the property of invariance of orientation is also passed validation by an experiment.The accepted manuscript in pdf format is listed with the files at the bottom of this page. The presentation of the authors' names and (or) special characters in the title of the manuscript may differ slightly between what is listed on this page and what is listed in the pdf file of the accepted manuscript; that in the pdf file of the accepted manuscript is what was submitted by the author

Advances in All-Solid-State Passively Q-Switched Lasers Based on Cr4+:YAG Saturable Absorber

All-solid-state passively Q-switched lasers have advantages that include simple structure, high peak power, and short sub-nanosecond pulse width. Potentially, these lasers can be applied in multiple settings, such as in miniature light sources, laser medical treatment, remote sensing, and precision processing. Cr4+:YAG crystal is an ideal Q-switch material for all-solid-state passively Q-switched lasers owing to its high thermal conductivity, low saturation light intensity, and high damage threshold. This study summarizes the research progress on all-solid-state passively Q-switched lasers that use Cr4+:YAG crystal as a saturable absorber and discusses further prospects for the development and application of such lasers