Advanced Materials Research Vols. 317-319

Abstract: Synthetic problem of variable structure control (VSC) for linear singular system with input and state time-delays is studied. Firstly, the original system with both input and state time-delays is written into a form without time-delay by a linear transformation. Secondly, the system without time-delay is decomposed into two low dimensional subsystems by a restricted system equivalent decomposed method. Thirdly, the quadratic performance index optimal control technique is introduced to design the optimal sliding mode for the restricted equivalent subsystems. By applying reaching law approach, the selected control law ensures that the solution trajectories of the system reach the switching manifold in finite time and have low chattering in the sliding motion. Finally, a simulation example is given to illustrate the feasibility and validity of the proposed method.

Abstract: There are friction characteristics, random disturbance, load variation and other nonlinear influencing factors in the multi-joint manipulator system generally. According to the problem that the traditional PID and fuzzy control are difficult to achieve rapid and high-precision control for this kind of system, a kind of robust adaptive fuzzy controller was designed based on fuzzy compensation under the circumstances that the fuzzy information can be known and all the state variables can be measured. Simultaneously, in order to reduce the computational load of fuzzy approximation and improve the efficiency of mathematical operation, a method that distinguishing different disturbance compensatory terms and approximating each of them respectively was adopted. The simulation results show that the robust adaptive fuzzy controller based on fuzzy compensation can restrain friction, disturbance, load variation and other nonlinear influencing factors.

Abstract: In orlder to find out the law between conductivity of polyglycol aliphatic acid ester and concentration and polymerization degree, the relationship between conductivity of polyglycol aliphatic acid ester and concentration and polymerization degree was teated by using DDS-II conductivity experimen instrument, by taking a typical polyethylene glycol 200( 400, 600) dilaurate as the research object. Firstly, the conductivities at the water content from 10% to 90% were tested in the room temperatrure. The results showed that conductivity of the same emulsion increases with increasing the water content, then decreases with increasing the water content. This is because that the emulsion is the O/W emulsion, conductivity increases with increasing the water content. Then the liquid crystal is generated in the emulsion leading to the increase trend of conductivity slowing down. The emulsion changs into the W/O emulsion at last resulting in conductivity decreases with increasing the water content. Secondly, the relationship between conductivity of emulsion and polymerization degree were tested. The results of the experiment show that: the higher the polymerization degree, the smaller the conductivity o f the emulsion is. The reason is the higher the polymerization degree, the less the conductible ions of the emulsion is, finally cause the conductivity changs smaller and smaller.

Abstract: A four freedom robot able to carry out automatic welding of offshore platform is introduced in this paper. The kinematic design of the robot has been designed according to the welding seam feature of T/Y/K-joint. The path planning of T/Y and the obstacle avoidance technique are used to study the robot’s collision avoidance welding on K-joint. In the process of K-joint path planning, the geometrical method was adopted to study the welding torch’s posture in branch gap. And for ensuring the postural stability of robot, the robot posture of a series welding points in single branch pipe condition was adjusted gradually in K-joint condition. The automatic welding process of K-joint was simulated in Solidworks. The result shows that the method could satisfy the collision avoidance requirement in the K-joint welding project.

Abstract: A new three-dimensional (3D) nonlinear guidance law is proposed and developed for bank-to-turn (BTT) with motion coupling. First of all, the 3D guidance model is established. In detail, the line-of-sight (LOS) rate model is established with the vector description method, and the kinematics model is divided into three terms of pitching, swerving and coupling, then by using the twist-based method, the LOS direction changing model is built for designing the guidance law with terminal angular constraints. Secondly, the 3D guidance laws are designed with Lyapunov theory, corresponding to no terminal constraints and terminal constraints, respectively. And finally, the simulation results show that the proposed guidance law can effectively satisfy the guidance precision requirements of BTT missile.

Abstract: Based on kinematics analysis, trajectory planning of a 4-DOF manipulator is researched on in this paper. Quintic polynomials is adopted to plan trajectory. The trajectory simulation of the manipulator is realized through using SimMechanics toolbox in MATLAB . The simulation experiments show the correctness and feasibility of the kinematics equations and algorithm of the manipulator trajectory planning.

Abstract: Aimed at work characteristics and work environment of auto loading manipulator for large caliber gun, its control system based on double CPU is designed. Then the paper expounds the components of the entire control system and corresponding principle. The control system can test control algorithm and motion trajedy plan in order to develop new control strategy and short development time.

Abstract: The objective of this paper is to discuss the probabilistic part of the model for robot group control applied in industrial applications. The proposed model is based on well-known concepts of Ubiquitous Computing [1] and enables contextual perception of a working environment. Compared with classical industrial robots, usually preprogrammed for a limited number of operations / actions, the system based on this model can react in uncertain situations and scenarios. The model combines ontology to describe the specific domain of interest and decision–making mechanisms based on Bayesian Networks (BN) to enable the work of a single robot without human intervention by learning Behavioral Patterns (BP) of other robots in the group.

Abstract: The current developed micro-grippers are not effectively used in micro-assembly within the scale of 0.01-10mm due to some practical problems. In this paper, we present a novel integrated micro-gripping system. In this system, the vac-sorb gripper and the micro-gripper based on a linear motion stage are employed together to stably pick up miniature mechanical structures in different shapes and dimensions. The gripping force is detected in real time and used as a feedback to control the action of the system. The design of the system and the implementation of the feedback mechanism are described in details. Experiments are taken and analyzed and the results show the designed functionality of the system.

Abstract: Assembly is one of the most important procedure in manufacturing complex miniature products. Batch assembly is limited by the manual manipulation, for which specially trained technicians is required. In order to automatically assembly certain complex miniature products consisting of multiple parts with different shape and various dimension, and also to reduce the production cost and improve efficiency, an assembly system was developed. Hardware architecture of the system was discussed in detail. Measurement and control strategies in assembling procedure were presented. Local feature extraction and fitting algorithms, reference datum setting were applied to overcome the occlusion. Linear and circular feature fitting from multiple local images of parts, coordinate transformation and the compensation of stages assembly error angle among three local coordinates were adopted to improve the measuring accuracy of vision system. Microscale force sensor was introduced to control the contact force, and the accuracy obtained is less than 1mN. Torque sensor was adopted for sensing the torque during the screw thread assembling, stepping motor and flexible coupler were applied to make the torque smoothly transferred, all of which help precisely measuring and controlling the torque during the M1.4 screw thread assembly.