Applied Mechanics and Materials Vols. 220-223

Abstract: It is difficult to obtain analytical solution to forward kinematics for parallel mechanism, and the speed of the solution based on conventional numerical solution method is lower, and hard to achieve real-time performance in motion control. In this paper, in order to avoid the two problems, a forward position solution method was proposed to approach the forward kinematics analytical solution exponentially. The Stewart platform was taken as example, its kinematics model was built, and then according a complex motion trajectory of moving platform given, the driving displacement of actuated joints was solved by inverse kinematics method, and then based on the driving displacement trajectory of actuated joints, using the forward position solution method, the forward kinematics solution was obtained, the simulation results showed that the forward position solution method can not only completely ensure real-time performance, but also attain very high accuracy, and so the forward position solution method for forward kinematics can be applied in motion control of parallel mechanisms.

Abstract: A novel 1-translation and 2-rotation parallel manipulator is investigated. An analytic solutions corresponding to the forward and inverse position are obtained. The influences by the three input variables on the three output variables are analyzed carefully and the valid working ranges of input and output variables are given. The work of the paper provided a solid foundation for mechanical structural design and real-time controlling of the novel parallel mechanism by structural parameter discussion.

Abstract: 5R joint manipulator kinematics model of position module is established, and according to the D-H method kinematical analyse of manipulator is processed, the space pose transformation matrix between adjacent rods of manipulator is established. The position equations of the manipulator is obtained and the Forward & Inverse solution of kinematics are got. The correctness of the forward & inverse solution are also verified through a engineering examples.

Abstract: Abstract: This paper mainly studies the problem of the movement of PRP cylindrical coordinate industrial manipulator. Based on the description of the manipulator position and gesture, the determination of coordinate of the rectilinear joint and rotary joint and the homogeneous coordinate transformation, the kinematical equation and its inverse solution can be deduced subsequently. It provides the theoretical basis for the following study.

Abstract: According to the perturbation in lithography positioning control system, a novel gain scheduled PID controller using a root mean square (RMS) signal is proposed. Perturbation is also referred as the stage hunting, and the positioning control system will be very weak against small disturbances such as electrical noise or even structural vibration of the building in which the stage is installed. The gain scheduled PID controller is used to minimize the stage hunting and simultaneously maximize the immunity to disturbances. Simulations results verify the effectiveness of the gain scheduled PID controller for the positioning control in the lithography stage, as compared with the traditional PID controller.

Abstract: An original 4-PUU parallelManipulator with three-dimensional translations and one rotational motion about Z axis was presented. Its positional inverse modals were set up by using the conversion of coordinates and projection in analytic geometry, and the method of the forward solution of theManipulator and corresponding numerical examples were given.This methods were verified by using MATLAB software,which can provide the basis for studying the parallel robots work space. And it has wide application in the fields of industrial robots, micromanipulators, virtual axis machine tools, damping platform, rehabilitation robot and other fields.

Abstract: Fruit picking is a seasonal and labor-intensive work. The industry requires automatic fruit picking due to increasing labor costs and variability in picking skill. High accuracy, simple structure and low cost are expected to make the robot be readily accepted and widely used. Cable-driven transmission is more preferable than traditional system for some of its merits benefiting the production of small and light-weight manipulator. In this paper, the design of a differential cable-driven manipulator is presented. Different way of cable-driven transmission are analyzed and compared. The selection of cable material and the way of cable fixation and preload are studied. The mechanical structure of the manipulator’s arm driven by a differential drive capstan is designed.

Abstract: This paper studies motion planning of underwater vehicle-manipulator system (UVMS) based on weighted minimum norm method with joint limit. In response to the problem that joint motion is limited and cannot give full play to kinematical performance in the range of allowed orientation angle, existed in the traditional weighted minimum norm method for joint limit, an improved method about motion planning is proposed. By means of introducing threshold in the joint potential function to change the initial position where the joint velocity is limited, the method makes that joint is only limited between threshold and boundary when it moves from the middle position to bilateral boundaries. A simulation is carried out to verify the proposed motion planning method.

Abstract: Aimed at the finite-time stabilization problem of a class of flexible manipulators, a finite-time state feedback stabilization controller was proposed in this paper. Firstly, the nonlinear model of flexible manipulators was transformed into linear system through the exact state feedback linearization. Based on the the finite time stabilization control method of the linear system, a finite-time state feedback stabilization controller was designed for the flexible manipulators. Furthermore, it was proved that all the states of flexible manipulators could be stabilized to equilibrium in finite time with the proposed controller. The simulation results showed that the performance of the flexible manipulators with the proposed finite-time state feedback controller was effective. At last, the analysis and comparison of the proposed controller and the dead-beat controller were given.

Abstract: This paper mainly study the Space Vector Pulse Width Modulation (SVPWM) algorithm of AC motor control system, Vector control strategy of the SVPWM voltage source inverter fed AC motor studied. In order to testify the correctness of the control strategy, simulation method is proposed to modify the motor speed and realize a simple and high performance speed control system. This system has been implemented on dynamic simulated tool simulation of MATLAB software in AC motor. Results show that the method gives satisfying rotor speed in the whole speed range and can improve the control precision.