Calibration of Parallel Machine Tools Using Fuzzy Interpolation Method
Ying Bai, Ph.D. Associate Professor, Dept of Computer Sci & Eng, Johnson C. Smith University, 100 Beatties Ford Rd., Charlotte, NC 28216, (704) 378-1148,
Dali Wang, Ph.D. Assistant Professor, Dept of Physics, Computer Sci & Eng.,Christopher Newport University, Newport News, VA 23606, (757) 594-7828,
In recent years, parallel machine tools (PMTs) have drawn more and more interest in study and research for their applications. The Parallel Machine Tools (PMTs) have the advantages of high operational accuracy, high rigidity, low price, high velocity, high acceleration and convenient usage in many industrial applications. However, because of the non-linear relationships existed between the actuators and the platforms, it is difficult to develop an accurate kinematic model for PMTs. The popular method for kinematic analysis includes two steps: non-linear modeling and non-linear equations solving, some of them are difficult and inefficient in actual applications.
To solve the problem presented above, a fuzzy interpolation method is developed and used for the calibration of the PMTs. The main advantage of using this technique is that this kind of calibration does not need to develop any kinemic modeling for PMTs, a so-called modeless method is adopted for this calibration.
Compared with other interpolation techniques, Fuzzy Interpolation Method (FIM) has the advantages of high calibration accuracy, low cost and faster in calibration processing. One of the most significant features of using FIM in the calibration of PMTs is that most PMTs have relatively small workspace, and this is specially suitable for the modeless and FIM technique in the PMTs’ calibration.
The basic idea of using this technique is to use a measuring device to measure some selected positions in the PMTs’ workspace to identify the position errors between the desired positions and the nominal positions of the end-effector of the PMTs. A standard calibration board is used as the measurement criterion. All those positions’ errors are stored based on each position’s coordinate. During the calibration process, the target position can be interpolated by using the FIM based on the position errors around the neighboring positions. Another advantage of using this technique is that this method can combine calibration and compensation process together to greatly reduce the time consuming in the compensation process.
A simulation studyin calibration of PMTs using the FIM is developed in this paper. Alsoa comparison between the different calibration methods with this method is discussed to indicate the advantages of using the proposed method over other methods.
Dr. Ying Bai’s Biography
Dr. YING BAI is an associate professor in the Department of Computer Science and Engineering at Johnson C. Smith University. His special interests include: Computer architecture, software engineering, mix-language programming, fuzzy logic controls, automatic and robots controls, and robots calibrations. His industry experience includes positions as a software and senior software engineers at companies such as Motorola MMS, Schlumberger ATE Technology, Immix TeleCom, and Lam Research.During recent years, Dr. Bai has published more than 15 academic research papers in IEEE Trans. journals and international conferences in robot calibrations. He also published 5 books with publishers such as Prentice Hall, CRC Press LLC and Springer. Most books are about the software programming, fuzzy logic applications in industrials and electronics circuits design.His sixth book entitled “Practical DatabaseProgramming with Visual Basic.NET” is under the contract with the Cambridge University Press and will be published in May 2008.