In order to reduce the cylinder work force on pull tower linkage of self-erecting tower crane, the geometric parameters of hinge points about linkage mechanism were optimized. Through the force analysis to whole system of bar linkage, the cylinder force of bar linkage is regarded as optimization objective function, and the geometric parameters of working devices hinge points are used to variables, then, the optimization model is established. The optimization design is conducted based on the fmincon function of MATLAB optimization toolbox. The curve about force of the cylinder with the towers rotation angle variation can be obtained. Comparison of the results before and after optimization is showed that the maximum force of cylinder is reduced 11.5%. It is shows the optimization method is quickly and effectively. The results of parameter optimization improve the working performance of the self-erecting tower crane.

No abstract

The purpose of this research work is to find the relationship between the driving force (F) of 3-TPS/TP parallel robot’s moving platform and the motion of tool tip, and provide reliable basis for the robot control. The Lagrange method is adopted to establish the dynamics model, and the results of the simulation by MATLAB are given in this paper. The movement of tool tip can be described by the angle α and β rotated around X-axis and Y-axis respectively, and the displacement z in the Z direction. The simulation results show that the value of F increases with the increase of the value of z, namely when the total length of the transmission rod decreases, F will increase to overcome the resistance caused by telescoping.

In order to improve the accuracy of the-5-DOF-hybrid robot motion control, it is necessary to establish a mathematical model of the error in the interpolation process. On the basis of the structure characteristics of five degrees of freedom hybrid robot and the algorithm of linear interpolation and circular interpolation, the error calculation patterns about the concave surface machining and convex surface machining are set up respectively in the paper. Then, examples are analyzed. The results show that the nonlinear error caused by using the straight-line interpolation method is much smaller than the normal vector rotation error and linear approximation error; when conducting surface machining, the error caused by the application of circular interpolation algorithm is less than linear interpolation error. By the comparison of the error analysis of different interpolation method, the control methods for reducing errors are proposed.

No abstract