Advances in Science and Technology Vol. 139

Abstract: In this paper, we propose a swing-up control law for the Pendubot, a type of two-joint, two-link, underactuated robot in which the shoulder joint is actuated and the elbow joint is unactuated, maintaining the elbow joint fully extended as much as possible. The proposed control law is designed by the energy-based method. Using the phase plane trajectories obtained from the angular and angular velocity oscillatory motion of the forearm, the target trajectory of the shoulder joint is calculated so that the trajectory is a small phase advance from the forearm. We design a tracking control law for the shoulder joint so that the forearm and the upper arm behave as a single pendulum. The effectiveness of the proposed method is verified by numerical simulation and actual experiments.

Abstract: With the rapid development of smart manufacturing, traditional processing is gradually moving towards automation, and the mold industry is no exception. Facing the ever-changing and complex product demands, the requirements for efficiency and precision are also increasing. However, currently most of the parts process planning rely on experienced personnel. They will decide the machining sequence and schedule according to the manufacturing method for the parts, and then use Computer-aided Manufacturing (CAM) software to simulate the processing time. Manual operation not only requires a lot of human-resource costs but also increase the lead time required for manufacturing, and even because of those human errors, resulting in delays for delivery. On the other hand, the trend of processing automation makes the accuracy of processing time estimation more important. Therefore, this study develops a navigating system to shorten the processing lead time by simplifying the operation process and combine regression analysis to improve the accuracy of machining-time estimation. This study uses ASP.NET MVC Framework as the framework and applied Computer-aided Design (CAD) software, Siemens NX (also known as NX Unigraphics, or UG for short), to create a machining navigating system on its secondary development module for Wire Electrical Discharge Machining (WEDM), Electrical Discharge Machining (EDM). Moreover, it integrates the existing CNC milling machine machining navigating process. This study identifies the features of WEDM and EDM through automatic recognition, and then navigate the user to perform Numerical Control (NC) programming with automatic settings and simple parameter input, and finally generate NC Codes automatically. For the EDM, the system will automatically decide the processing range and generate electrode heads after the feature recognition is confirmed. The processing parameters will be stored in the Microsoft SQL Server Express database and sent to the linear regression analysis model. The actual machining time is used as the training label to optimize the parameters in order to improve the accuracy of the estimated working hours. The navigating system in this study can effectively shorten the processing simulation operation time by 84%, and at the same time a large amount of training data for regression analysis training can be generated. The maximum and average errors of machining time is reduced from 45%/32% to 23%/12%, which improves production efficiency and the accuracy of scheduling.