In the process of the robot practical working, the change of motion direction of trajectory is inevitable. When the direction changes dramatically, the sharp angle between adjacent trajectories, which can generate the vibration of robot, affects the service life of the robot. In order to deal with the sharp angle between adjacent trajectories, we propose a method which can deal with the sharp angle transferring by inserting transition arc, which is called position level, to solve the trajectory speed control problem. We analyze three basic analytic trajectories-space line, space arc, and space parabola-and present the formula for calculating the parameters of circular-arc-related parameters and propose the implementation process of algorithm of robot system. Through the simulation and experiment, this method can solve the sharp angle trajectory transfer problem effectively, increase the transfer speed dramatically, and reduce the vibration of robot's mechanical structure.
Abstract-The interpolation method and feedrate adaptation control are the two most important factors to influence the quality and accuracy of manufacturing for NURBS on CNC systems. In this paper, we propose an integrated approach to solve the feedrate adaptation control NURBS interpolation problem by considering interpolation and feedrate control together with the "tail" handling. We propose a de-Boor-algorithm-based NURBS interpolation model with the second-order Taylor expansion and design a new algorithm to calculate actual deceleration points to remove the "tail" based on a novel concept, reverse NURBS interpolation. To supplement the tail removal in velocity control, a novel feedrate adaptation control algorithm is proposed. The experimental results show that our integrated method can significantly improve the accuracy.
In order to realize a high speed and high accuracy prosthesis shaping equipment (PSE) control system, this paper proposes a new software-hardware architecture of a five-axis high performance NC system. The software part of the proposed architecture follows the rules of the hierarchy and modularity. The inheritance, scalability, and stability are ensured on the whole system and local parts. According to the idea of modular design, the framework uses the client-server mode in the communication and scheduling level. With this way, the reliability of the module management is ensured. The hardware part of the proposed architecture consists of two main parts: the controller and I/O module. The controller is based on FPGA and uses PCI bus and IPC interface. The I/O module is based on ARM + CPLD and uses CAN bus to communicate with the controller. This paper also studies some key problems such as the driving signal producing mechanism. The results of prosthesis shaping equipment prototype show that the system which uses the proposed architecture can reach the positioning accuracy up to 0.02 mm and 3D typical surface cutting accuracy up to 0.02 mm, and this accuracy level already leads similar products in market.
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