Browsing by Issue Date, starting with "2003-06-30"
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- Position and force control of a walking hexapodPublication . Silva, Manuel; Tenreiro Machado, J. A.This paper compares the performance of classical position PD algorithm with a cascade controller involving position and force feedback loops, for multi-legged locomotion systems and variable ground characteristics. For that objective the robot precribed motion is characterized in terms of several locomotion variables. Moreover, we formulate several performance measures of the walking robot based on the robot and terrain dynamical properties and on the robot hip and foot trajectory errors. Several experiments reveal the performance of the different control architectures in the proposed indices.
- Fractional-order hybrid control of robots manipulatorsPublication . Ferreira, N. M. Fonseca; Tenreiro Machado, J. A.This paper presents the implementation of fractional-order algorithms in the position/force hybrid control of robotic manipulators. the system performance and robustness is analyzed in the time and frequency domains. The effect of dynamic backlash and flexibility is also investigated.
- Fractional order dynamics in a Genetic AlgorithmPublication . Pires, E. J. Solteiro; Tenreiro Machado, J. A.; Oliveira, P. B. de MouraThis work addresses the fractional-order dynamics during the evolution of a Genetic Algorithm population (GA) for generating a robot manipulator trajectory. The GA objective is to minimize the trajectory space/time ripple without exceeding the torque requirements. In order to investigate the phenomena involved in the GA population evolution, the mutation is exposed to excitation perturbations and the corresponding fitness variations are evaluated. The input/output signals are studied revealing a fractional-order dynamic evolution, characteristic of a long-term system memory.