Papers by Keyword: Parallel Kinematic Machines

Abstract: Because of the control complexity of the Parallel Kinematic Machines (PKMs), such mechanisms may suffer from lack of accuracy at high speed. Unfortunately, conventional motion controllers have very limited flexibility because they are designed for Cartesian coordinates. Therefore, the motion control system for PKMs with both high performance and open architecture is urgently demanded. In this paper, an open architecture control system for PKMs based on multi-DSP parallel procession is presented. Then, the hierarchical distributed control strategy is discussed in details. In addition, the realization of an interactive communication interface among DSP processors is presented. According to the testing results, the developed system is capable of obtaining an interpolation sampling period at least 3 times faster than that could be offered by most controllers based on single-DSP, thus it is available for high-speed and high-accuracy control of PKMs.

Abstract: Based on the proposed 4PUS-1RPU parallel mechanism a 5-axis Parallel Kinematic Machine (PKM) scheme has been developed and the dynamic characteristics of the PKM have been investigated in detail. To avoid the intensive computation caused by finite element analysis in the research, two typical metamodeling techniques of Response Surface Methodology (RSM) and its artificial neural network enhanced technique were employed as the robust design approaches. Comparing the results obtained from the direct RSM the modeling accuracy by the artificial neural network enhanced RSM can be improved.

Abstract: In this paper a novel constraint calibration technique for Stewart platform based Parallel Kinematics Machine(PKM) is presented. A commercial trigger probe and a developed double-ball bar gauge are employed to aid the calibration. In the measuring process the characterized errors can be obtained by comparing the nominal characterized size calculated by the function using the measuring data with the real size of the double-ball gauge. An optimization approach is used to calculate the PKM structural errors, and these errors can be finally compensated into the control model. The error transferring matrix with regard to the structural error of PKM can be formulated. The calibration efficiency can be improved by the automatic calibration operation with the doubleball bar gauge. The developed calibration system has been applied in the industry where the PKM is used for machining the turbine vane, and the machining quality can meet the requirements of the specifications. The presented calibration scheme is generic to be applied for the wide range of PKMs.

Abstract: Parallel robots have often been used during the last decade because of their advantages, such as: good dynamic behavior, easiness of inverse kinematics, and higher accuracy etc. Despite those advantages, parallel robots are criticized in relation to their small work space, and not really modular topology and complex mechanical architecture. Industrial experience has realized that the major disadvantage of parallel robots is the small dimension of work space. Strong economical reasons and all technical advantages of parallel robots recommend these robots to do tasks that are proper to machine tools.