In this paper, we present an optimal design and control algorithm for multi-input binary-segmented Shape Memory Alloy (SMA) actuator arrays applied to a multi-degree-of-freedom (DOF) robot manipulator as it tracks a desired trajectory. The multi-DOF manipulator used for this paper is a 3-DOF-robot finger. A multi-input binary-segmented SMA actuator drives each DOF. SMA wires are embedded into a compliant vessel, such that both electric and fluidic (hot/cold) input can be applied to the actuators. By segmenting the SMA actuators, each segment can be controlled in a binary fashion (fully contracted/extended) to create a set of discrete displacements for each joint of the manipulator. To design the number of segments and length of each segment, an algorithm is developed to optimize the workspace. To optimize the workspace, it is desired to have a uniform distribution of reachable points in Cartesian space. Moreover, the number of neighbors (points that can be reached just by one control command from the current configuration) and the computational cost are important in workspace optimization. Graph theory search techniques based on the A* algorithm are employed to develop the control algorithm. A path-cost function is proposed to optimize the cost, which is a combination of actuation time, energy usage, and kinematic error. The kinematic error is estimated as the deviation between the actual and desired trajectory. The performance of the search algorithm and cost function are validated through simulation.
In this paper, the numerical study of cold flow over two types of regular and wavy V-gutter flame holders has been presented. The edges of the V-gutter, which are smooth in the regular case, are shaped in a sinusoidal form with different phase angles on upper and lower edges. The three-dimensional numerical analysis has been performed using the finite volume method and the renormalization group k–ɛ model has been used for turbulence modeling. The results were compared and validated by an existing experimental work based on the particle image velocimetry method. This study provided the fluid flow structure behind the V-gutter, the dimensions of the recirculation region, the behavior of vortex shedding phenomenon, and the static pressure distribution in the wake area. According to the results, the recirculation length for the sinusoidal case with 90 ° of the phase difference is the largest compared with the other cases, which increases the mass flow rate of the fresh unburnt mixture into the recirculation region and improves flame stability. The results also show that the 90 ° wavy V-gutter case has the lowest pressure drop in the wake region, which reduces the drag coefficient against the main flow. The values of the Strouhal number are approximately the same and equal to 0.27 for both cases (the regular and the 90 ° cases). Therefore, it is concluded that the 90 ° wavy V-gutter shows better performance than the regular V-gutter in flame stabilization.
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