Papers by Author: Ji Man Luo

Abstract: The design scheme of 3TPS / TP new robot test system design is described in this article, and Linux-based embedded system as the core is proposed, with displacement and tension sensor detecting robot motion and mechanical performance, the overall program is achieved by an interactive interface functions. The hardware design and software design framework is advanced, not only the high-precision performance of the hardware system is ensured, but also the multi-functional development of software is realized. Finally, experimental test is carried out, the detection of robot to its motion precision and the load characteristic is implemented, the experimental results verify the feasibility of the system solution.

Abstract: Supporting system of external suspension tower crane is the key factor which impairs the safety of the tower cranes. In this article, the problem is studied about the influence of different supporting point stiffness on the force of the tower crane external suspension. Based on the structural mechanics theory, the displacement of the lower statically indeterminate beam and the horizontal displacement of the upper statically indeterminate truss are solved firstly, then the stiffness of the supporting point on the lower beam and the entirety stiffness of the upper horizontal combination struts can be obtained. We can get the optimal supporting structure by drawing the relationship of stiffness1-stiffness2-force which is of significant to the external suspension’s design and installation in Matlab software.

Abstract: 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.

Abstract: 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.

Abstract: The purpose of this research work is to find the relationship between the movement and force (torque) of 3-TPS/TP parallel robot, the Lagrange method is adopted to establish the dynamics model, and the results of the simulation by ADAMS are given in this paper. The curve is about the change of force come from every joint of active chains with time. It provides a lot of data for further reference to choose the drive device.

Abstract: In order to avoid the damage of structure caused by the vibration, the natural frequency and vibration mode figure of the stiffness characteristics of the hoist’s structure should be analyzed. Modal analysis method is presented for solving above problem, and the first 6 order natural frequencies in different working conditions have been calculated in this paper. Vibration mode figure of structure system have been simulated corresponding to the first 6 order natural frequencies based on ANSYS. It is shows that the external excitation force have a great influence on the top of the free end when the cage moves to a different location. So, in the actual construction, the stiffness of top free ends connected tie-in device should be strengthened, therefore the system stability will be improved.

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.

Abstract: Vibration is one of problems of mechanical structures, because structural resonance or fatigue will be caused by the vibration, thus it will be cause the damage of structure. In order to avoid the damage of structure, it is necessary to analyze the stiffness characteristics of the structure，which is the natural frequency and vibration mode figure, therefore unnecessary loss because of the resonance causes can be effectively avoided. By using modal analysis method which is in the structural dynamics, vibration pattern of structure system can be visually obtained from theoretical calculation and ANSYS simulation. The first 6 order natural frequencies of different working conditions have been calculated in this paper, dynamic displacement formula in external excitation have been shown when the cage move to a different location. Vibration mode figure of structure system can be drawn corresponding to the first 6 order natural frequencies, based on the finite element analysis software ANSYS, vibration image of structure system have been simulated corresponding to the first 6 order natural frequencies. The dynamic characteristics of structure system are affected when the cage to a different location. Through the cage to a different location, external excitation force have a great influence on the top of the free end, in the actual construction, the top free ends connected tie-in device stiffness should be strengthened, the system stability will be improved.

Abstract: The grinding fluid has the function of cooling and lubricating only when it breaks through the airflow barrier near the grinding wheel and enters into the contact area between the grinding wheel and the workpiece. The air-fluid two-phase flow software is used to simulate the characteristics of the grinding fluid field based on VOF, and the special constraint conditions of the outlet pressure are not applied in simulation. The characteristics of the grinding fluid jet and the real moving characteristics of the grinding fluid between the jet flow area and the grinding area are analyzed. It provides the research foundation for the parameters of the grinding fluid supplying.

Abstract: Super-high speed point grinding is a new high-speed grinding technology with some excellent machining performances. In such a grinding process, there is a high-speed airflow rotating around the edge of grinding wheel which hinders the grinding fluid from injecting into the contact area and makes the fluid atomization and splash during grinding process, so as to decrease the ratio of effective grinding fluid into contact area and affect the surface integrity of workpiece. In this paper, the structure and properties of grinding fluid jet is analyzed, the velocity distribution field of the round turbulent jet is discussed theoretically and simulated. Based on the pressure balance principle, a mathematical model is established for the jet velocity at the fluid nozzle, which enables the grinding fluid to pass through the high speed airflow and enter into the contact area. According to the analysis of the grinding fluid velocity in the jet core, an engineering formula is given to calculate the position limit of nozzle during grinding process, as well as a practical design example for the high speed grinding machine is presented.