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Abstract: The square kilometre array (SKA) is an ambitious world cooperation project to develop the next generation large radio telescope with the collecting area of 1 square kilometre. A parallel cable manipulator is used to provide large workspace and accomplish the coarse tracking of the feed. Considering the characteristics of large time-varying delay of the large span cable actuator of the parallel cable manipulator, a fuzzy model reference learning controller (FMRLC) is proposed to accomplish the coarse tracking. The FMRLC consists of a direct fuzzy controller, a reference fuzzy inverse model and a fuzzy learning mechanism. This FMRLC adjusts the direct fuzzy controller so that the closed-loop system acts like a pre-specified reference model using the fuzzy learning mechanism. The comparative simulation results with a linear PD control demonstrate the better performance of the developed fuzzy controller, which have built a solid base for the engineering implementation of the high precision tracking of the feed for the SKA. [Copyright &y& Elsevier]

A large parallel-cable manipulator for the feed-supporting system of a next-generation large radio telescope is presented in this paper. The approximate kinematics model of the system is developed to improve real-time controllability, and the rationality of this approximation is validated by a kinematics accuracy analysis. In order to guarantee the effectiveness of control, the singularity of the large parallel-cable manipulator is analyzed (including kinematics and force singularities). The control strategy of the parallel-cable feed-supporting system is also proposed. © 2001 John Wiley & Sons, Inc. [ABSTRACT FROM AUTHOR]

A real-coded genetic design methodology for an optimal kinematic Stewart platform is presented in this article. The Jacobian matrix connecting the dexterity performance of the parallel platform is first deduced, and then the condition number of Jacobian matrix is employed as the objective function to implement the optimal kinematic design of Stewart fine tuning platform for a large spherical radio telescope. A niched-penalty approach is used to transform this optimal kinematic design problem to an unconstrained one, and a niching technique and the dynamic mutation operator are applied. A kinematic accuracy comparison of the genetically designed Stewart fine tuning platform with the quasi-Newtonian designed platform is made. The comparison results have shown that the kinematic accuracy of the genetically designed Stewart fine tuning platform has a much higher accuracy and compact structure than that of the quasi-Newtonian designed platform, which guarantees the implementation of high accuracy requirement of trajectory tracking and reduces the disturbance of random wind for large radio telescopes. © 2001 John Wiley & Sons, Inc. [ABSTRACT FROM AUTHOR]

For the requirement of trajectory tracking of large spherical radio telescopes, a large fine tuning platform based on the Stewart platform is presented in this paper. The mathematical model for kinematics control is developed with coordinate transformation, and a dynamic analysis is made using a Jacobian matrix. Furthermore, the singularity analysis of the designed platform is also made using the determinant of the Jacobian matrix, which has built a solid base for the tracking control. The kinematics accuracy is obtained by position vector analysis. These results have shown the validity of the designed fine tuning platform for the feed source trajectory tracking control of large spherical radio telescopes. ©2000 John Wiley & Sons, Inc. [ABSTRACT FROM AUTHOR]