Open Access. Powered by Scholars. Published by Universities.®
Articles 1 - 8 of 8
Full-Text Articles in Aerospace Engineering
Design Of A Linear Time-Varying Cross-Coupled Iterative Learning Controller, K. L. Barton, Douglas A. Bristow, Andrew G. Alleyne
Design Of A Linear Time-Varying Cross-Coupled Iterative Learning Controller, K. L. Barton, Douglas A. Bristow, Andrew G. Alleyne
Mechanical and Aerospace Engineering Faculty Research & Creative Works
In many manufacturing applications contour tracking is more important than individual axis tracking. Many control techniques, including iterative learning control (ILC), target individual axis error. Because individual axis error only indirectly relates to contour error, these approaches may not be very effective for contouring applications. Cross-coupled ILC (CCILC) is a variation on traditional ILC that targets the contour tracking directly. In contour trajectories with rapid changes, high frequency control is necessary in order to meet tracking requirements. This paper presents an improved CCILC that uses a linear time-varying (LTV) filter to provide high frequency control for short durations. The improved …
Moving Object Recognition And Guidance Of Robots Using Neural Networks, Abhijit Neogy, S. N. Balakrishnan, Cihan H. Dagli
Moving Object Recognition And Guidance Of Robots Using Neural Networks, Abhijit Neogy, S. N. Balakrishnan, Cihan H. Dagli
Mechanical and Aerospace Engineering Faculty Research & Creative Works
The design of a robust guidance system for a robot is discussed. The two major tasks for this guidance system are the online recognition of a moving object invariant to rotation and translation, and tracking the moving object using a neural-network-driven vision system. This system included computer software ported to the IBM PC and interfaced with an IBM 7535 robot. The operation of this guidance system involved recognition of a moving object and the ability to track it till the robot and effector was in close proximity of the object. It was found that the robot was able to track …
Genericity And Singularities Of Robot Manipulators, Ming-Chuan Leu, D. K. Pai
Genericity And Singularities Of Robot Manipulators, Ming-Chuan Leu, D. K. Pai
Mechanical and Aerospace Engineering Faculty Research & Creative Works
The kinematic singularities of robot manipulators are studied from the point of view of the theory of singularities. The notion of a "generic'' kinematic map, whose singularities form smooth manifolds of prescribed dimension in the joint space of the manipulator, is examined. For three-joint robots, an equivalent algebraic condition for genericity using the Jacobian determinants is derived. This condition lends itself to symbolic computation and is sufficient for the study of decoupled manipulators. Orientation and translation singularities of manipulators are studied in detail. A complete characterization of orientation singularities of robots with any number of joints is given. The translation …
Hierarchical Neurocontroller Architecture For Intelligent Robotic Manipulation, Xavier J. R. Avula, Luis C. Rabelo
Hierarchical Neurocontroller Architecture For Intelligent Robotic Manipulation, Xavier J. R. Avula, Luis C. Rabelo
Mechanical and Aerospace Engineering Faculty Research & Creative Works
A hierarchical neurocontroller architecture consisting of two artificial neural network systems for the manipulation of a robotic arm is presented. The higher-level neural system participates in the delineation of the robot arm workspace and coordinates transformation and the motion decision-making process. The lower one provides the correct sequence of control actions. The capabilities, including speed, adaptability, and computational efficiency, of the developed architecture are illustrated by an example.
Robust Nonlinear Control Of Brushless Dc Motors For Direct-Drive Robotic Applications, N. Hemati, J. S. Thorp, Ming-Chuan Leu
Robust Nonlinear Control Of Brushless Dc Motors For Direct-Drive Robotic Applications, N. Hemati, J. S. Thorp, Ming-Chuan Leu
Mechanical and Aerospace Engineering Faculty Research & Creative Works
The control problem associated with brushless DC motors (BLDCMs) for direct-drive robotic applications is considered. In order to guarantee the high-performance operation of BLDCMs in such applications, the effects of reluctance variations and magnetic saturation are accounted for in the model. Such a BLDCM model constitutes a highly coupled and nonlinear dynamic system. Using the transformation theory of nonlinear systems, a feedback control law, which is shown to compensate for the system nonlinearities, is derived. Conditions under which such a control law is possible are presented. The need for the derivation of explicit commutation strategies is eliminated, resulting in reduction …
Planning Optimal Robot Trajectories By Cell Mapping, W. H. Zhu, Ming-Chuan Leu
Planning Optimal Robot Trajectories By Cell Mapping, W. H. Zhu, Ming-Chuan Leu
Mechanical and Aerospace Engineering Faculty Research & Creative Works
A cell-mapping method is introduced for planning global trajectories of robotic manipulators in cases where the cell space is composed of combination pairs of plane cells. With the proposed method, optimal trajectory problems in the free field and in the obstacle-constrained field are studied. Two numerical examples are given to show the obtained optimal trajectories and controls.
Robust Nonlinear Control Of Brushless Dc Motors In The Presence Of Magnetic Saturation, N. Hemati, J. S. Thorp, Ming-Chuan Leu
Robust Nonlinear Control Of Brushless Dc Motors In The Presence Of Magnetic Saturation, N. Hemati, J. S. Thorp, Ming-Chuan Leu
Mechanical and Aerospace Engineering Faculty Research & Creative Works
A robust control law is derived and examined for a direct-drive robot arm driven by a brushless DC motor (BLDCM). The complete dynamics of the motor and its interaction with the robot arm are accounted for. This is important, since in a direct-drive servo system the torque generated by the motor is directly transmitted to the load. Effects of magnetic saturation as well as reluctance variations are accounted for, in order to ensure accuracy. The effectiveness of the method is examined through computer simulations. The computational complexity of the overall control scheme is such that it can be readily used …
Generic Singularities Of Robot Manipulators, Ming-Chuan Leu, D. K. Pai
Generic Singularities Of Robot Manipulators, Ming-Chuan Leu, D. K. Pai
Mechanical and Aerospace Engineering Faculty Research & Creative Works
The singularities of the differential kinematic map, i.e. of the manipulator Jacobian, are considered. The authors first examine the notion of a generic kinematic map, whose singularities form smooth manifolds of prescribed dimension in the joint space of the manipulator. For three-joint robots, an equivalent condition for genericity using determinants is derived. The condition lends itself to symbolic computation and is sufficient for the study of decoupled manipulators, i.e. manipulators that an be separated into a three-joint translating part and a three-joint orienting part. The results are illustrated by analyzing the singularities of two classes of three-joint positioning robots.