Tip position control of flexible arms with friction in the joints is studied in this paper. The control scheme is based on two nested loops: an inner loop to control the position of the motor and an outer loop that co...
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Tip position control of flexible arms with friction in the joints is studied in this paper. The control scheme is based on two nested loops: an inner loop to control the position of the motor and an outer loop that controls the tip position. The design of the inner loop is quite straightforward. However, the the outer loop may be designed several different ways. Three methods are proposed here to control the tip position: a feedforward based control method, a method that eliminates the principal natural frequency of the beam, and a method based on the sensing at several intermediate points of the mechanical structure of the arm. In the ideal case (when there are no perturbations), these three methods produce the same dynamic behavior of the arm. This paper compares their performances when perturbations and unmodelled dynamics are present. In particular, three cases are considered, i.e.. external disturbances in the tip. unmodelled dynamics in the inner loop, and changes in the carried load. Analytic and simulation studies have been carried out to compare these methods and the results show that the third method which uses sensing at the intermediate points of the arm, had the best performance in all three cases.
作者：
Theocharis, J.Petridis, V.Dr.-Ing. John Theocharis (1956) graduated as an Electrical Engineer from Aristotelian University of Thessaloniki.Greece
in 1980. From 1980 to 1985 he has been with the scientific staff of the Department of Electrical Engineering at the Aristotelian University where he received the Ph.D. degree in 1985. Since 1986 he is working as a lecturer and in 1990 he became assistant professor at the Department of Electronics and Computer Engineering in the m e university. His research activities include control power electronics and electrical motor drives. Recently he is working with the Neural Network Systems with applications to field oriented control problems. Aristotelian University of Thessaloniki School of Engineering Faculty of Electrical Engineering Dept. of Electronics & Computer Engineering P.O. Box 438 GR-Thessalonikil/Greece.T+3131/219784Fax + 3031/274868) Prof. Dr.-Ing. Vasilis Petridis (1946) graduated from National Technical University of Athens
Greece in 1969.He obtained the M.Sc. and the Ph.D. in electronics and systems from the University of London in 1970 and 1974. respectively. H i s interests include applied automatic control neural networks drives dynamic systems robotics etc. He is currently professor in the Department of Electronics and Computer Engineering of the University of Thessaloniki. (Aristotelian University of Thessaloniki. School of EngineeringFaculty of Electrical Engineering Dept. of Electronics & Computer Engineering P.O. Box 438. GR-ThessaloniW Greece T+3031/219784.Fax+3031/274868)
The procedure of harmonic insertion is generalized in this paper. Analytical expressions of the voltage spectra are derived. The insertion of the 3rd harmonic to the modulating signal, which is of particular interest,...
The minimum-time control of robot arms has usually been implemented as a two-task procedure, where the appropriate trajectory planning is performed off-line, and then tracking is carried out on-line to achieve the des...
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The minimum-time control of robot arms has usually been implemented as a two-task procedure, where the appropriate trajectory planning is performed off-line, and then tracking is carried out on-line to achieve the desired motion. However, such an approach is unacceptable whenever the motion is dependent on the on-board sensory equipment operated during the application. In the paper, an on-line trajectory generator is described in which the history of motion is planned and executed in real time. The computational complexities of the minimum-time requirements of the motion have been reduced significantly by distributing the proposed algorithm on a multiprocessor system. The practical implementation of the distributed system on a T800 transputer network shows its efficiency in accomplishing the required task. Real-time simulation results are reported for a PUMA 560 robot manipulator.
In this paper, an approach to modelling of a robotic assembly cell is proposed and a method for managing the cell operation is described using a knowledge base. Since the modelling structure is based on the concept of...
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In this paper, an approach to modelling of a robotic assembly cell is proposed and a method for managing the cell operation is described using a knowledge base. Since the modelling structure is based on the concept of the state variable, the relationships between states are described by the state transition map (STM). The knowledge-bases for state transition and assembly job information are obtained from the STM and the assembly job tree (AJT), respectively. Using the knowledge-base, the system structure is discussed in relation to both managing the cell operation and evaluating the performances. Finally, a simulation algorithm is presented with the simulation results to show the significance of the proposed modelling approach.
An algorithm is presented for the on-line generation of minimum-time trajectories for robot manipulators. The algorithm is designed for intelligent robots with advanced on-board sensory equipment which can provide the...
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An algorithm is presented for the on-line generation of minimum-time trajectories for robot manipulators. The algorithm is designed for intelligent robots with advanced on-board sensory equipment which can provide the position and orientation of the end-effector. Planning is performed in the configuration (joint) space by the use of optimised combined polynomial splines, along with a search technique to identify the best minimum-time trajectory. The method proposed considers all physical and dynamical limitations inherent in the manipulator design, in addition to any geometric path constraints. Meeting the demands of the heavy computations involved lead to a distributed formulation on a multiprocessor system, for which an intelligent control unit has been created to supervise its proper and practical implementation. Simulation results of a proposed case study are presented for a PUMA 560 robot manipulator.
The minimum-time motion of robot manipulators is solved by defining a suitable time history for the arm end-effector to traverse. As the planning is performed in the configuration space, the uniqueness of the proposed...
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The minimum-time motion of robot manipulators is solved by defining a suitable time history for the arm end-effector to traverse. As the planning is performed in the configuration space, the uniqueness of the proposed algorithm emerges from the combination of both cubic and quadratic polynominal splines. Furthermore, the highly efficient time optimisation procedure could be applied to local segments of each joint trajectory, leading to a significant reduction of the travelling time. In addition, the ability to perform a search in the work space is granted, exploiting all possible options for an optimum motion. The method proposed considers all realistic physical limitations inherent in the manipulator design, in addition to any geometric constraints imposed on the path. Simulation programs have been written, and results are reported for the Unimation PUMA 560 robot manipulator.
We present a model-based object recognition system for specular object. Objects with specular surfaces present a problem for computer vision. Simulating object appearances by using the sensor model and the object mode...
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We prove a cost translation theorem that allows one to solve the general multi-rate LQG problem by first performing a lifting isomorphism and then solving a standard (shift-invariant, single-rate) LQG problem.
We prove a cost translation theorem that allows one to solve the general multi-rate LQG problem by first performing a lifting isomorphism and then solving a standard (shift-invariant, single-rate) LQG problem.
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