This paper proposes a control scheme for the current injected by an Active Power Filter (APF) that has an LCL filter at its output. The proposed structure relies in a Two-Degrees-of-Freedom (2DOF) controller in which resonant terms are included. The 2DOF scheme follows the current reference at the fundamental frequency of the grid and damps the resonance phenomenon of the LCL filter, whereas the resonant regulators allow a proper tracking of the harmonics. This is achieved with only the measurement of the current injected by the APF into the grid, without the need for additional measurements or observers. In order to assess the performance of the controllers, a Hardware-In-the-Loop (HIL) emulation has been carried out. The results show a good time response, allowing the compensation of current disturbances at both the fundamental frequency and its harmonics.

Flexible-finger hands/grippers have some advantages over rigid ones when used in grasping tasks. For example, they absorb energy during the impact, which make them suitable in delicate manipulation or human interaction. In this work, we look at their performance during grasping tasks, analyzing the effect of some design parameters like precurvature and stiffness of the links, number/DOFs of fingers or scale of the hand. Our work is based on a grasp stability analysis together with a grasp closure analysis adapted to flexible hands. Simulation and experimental tests with a two flexible-finger gripper are provided as validation of our analysis.

Flexible manipulators have many advantages over rigid robots when used in grasping tasks, owing to the characteristic flexibility of the materials used in their construction, which allow them to absorb energy during impact and make them controllable in order to limit the force applied during contact. In this paper, a two-flexible-finger gripper with a simple sensory feedback system is proposed. A generalized proportional-integral controller is implemented to acquire high control accuracy, while eliminating the need for derivatives of system output. The performance of this force feedback control system is investigated when mounted on a 6-degree-of-freedom (6-DOF) manipulator and grasping different objects. The experimental results indicate that the system proposed is able to manipulate different types of objects (both rigid and flexible) in an industrial environment by perfectly controlling the applied contact torque.