Browsing by Issue Date, starting with "2000-10"
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- An Automated Verification Process Based on Scan TechniquePublication . Alves, Gustavo R.; Krug, Margrit R.; Lubaszewski, Marcelo S.; Ferreira, Jose M.Matching the results achieved during circuit simulation with those extracted from circuit functioning is a common verification process. A large number of current verification techniques use the input / output vectors produced during functional simulation as the test vectors applied / compared against the circuit responses. Techniques that are more complete include extracting the values of internal sequential nodes and comparing these using internal scans. This paper describes a solution for verifying digital designs implemented in currently commercial available CPLDs. All internal flip-flops are included in a scan-chain accessible through the BST infrastructure (using a user-defined optional instruction), while the BS cells are used to apply the input test vectors and capture the circuit responses. These BS cells can either belong to the device-under-test or to other devices, the first controlled through the optional INTEST instruction and the second controlled through the mandatory EXTEST instruction. To speed up the verification process, the test program is automatically generated from information that encompasses the design & development phase.
- Teaching robot modelling and control with RobLibPublication . Ferreira, N. M. Fonseca; Tenreiro Machado, J. A.The paper presents a program for robotics education that runs on standard PC's under the Microsoft Windows environment. The RobLib package is designed for undergraduate students and emphasis the fundamental aspects of robot modelling and control. The software is self-explanatory and uses menus, dialog boxes with figures and context-dependent on-line help. In this perpective, students are motivated to investigate on the workspace, kinematics, dynamics, trajectory planning, position and force control of manipulators. Based on this first experience, further studies on robotics, using more sophisticated packages and concepts, are, then, more attractive from the students point of view.
- Position/force control of biped locomotion systemsPublication . Silva, Filipe M.; Tenreiro Machado, J. A.This paper addresses the problem of modelling and control of a biped robot by combining Cartesian-based position and force control algorithms. The walking cycle is divided in two phases: sinlge support, in which one leg is in contact with the ground and the other leg swings foward, and double support, in which the foward leg absorbs the impact and gradually accepts the robot's weight. The contact of the foot with the constrained surface is modelled through linear spring-damper systems. The proposed control approach is based on simple motion goals taking into account the reaction forces between the feet and the ground. The control algorithm is tested through several experiments and its effectiveness and robustness is discussed.
- Position/force control of biped walking robotsPublication . Silva, Filipe M.; Tenreiro Machado, J. A.This paper addresses the problem of modelling and control of biped robot by combining Cartesian-based position and force control algorithms. The complete walking cycle is divided in two phases: i) single support - in which it is studied the trajectory controllability based on simple motion goals and ii) exchange of support - in which the foward leg absorbs the impact and then gradually accept the robot's weight. The control of the foot with the constrained surface is modelled through linear spring-damper systems. The system's controllability is enhanced through the insertion of a dynamic selection matrix that modifies the actuating profile in each phasse. The control algorithms are simulated and their effectiveness and robustness are discussed.