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2013). Experimental results for the exible joint cable-suspended manipulator of ICaSbot. Robotica, 31, pp 887-904 SUMMARYIn this paper, design, dynamic, and control of the motors of a spatial cable robot are presented considering flexibility of the joints. End-effector control in order to control all six spatial degrees of freedom (DOFs) of the system and motor control in order to control the joints flexibility are proposed here. Corresponding programing of its operation is done by formulating the kinematics and dynamics and also control of the robot. Considering the existence of gearboxes, flexibility of the joints is modeled in the feed-forward term of its controller to achieve better accuracy. A two sequential closed-loop strategy consisting of proportional derivative (PD) for linear actuators in joint space and computed torque method for nonlinear end-effector in Cartesian space is presented for further accuracy. Flexibility is estimated using modeling and simulation by MATLAB and SimDesigner. A prototype has been built and experimental tests have been done to verify the efficiency of the proposed modeling and controller as well as the effect of flexibility of the joints. The ICaSbot (IUST Cable-Suspended robot) is an underconstrained six-DOF parallel robot actuated by the aid of six suspended cables. An experimental test is conducted for the manufactured flexible joint cable robot of ICaSbot and the outputs of sensors are compared with simulation. The efficiency of the proposed schemes is demonstrated.

This paper addresses the impact of high wind power penetration level on damping of the electromechanical modes of oscillation and design of a power oscillation damping (POD) controller for doubly fed induction generator (DFIG)based wind farm. An auxiliary control loop has been added to rotor side converter (RSC) in the form of cascade control with outer active/reactive power control and inner rotor current control loops. It is shown that this residue-based POD controller significantly improves the inter-area oscillation damping. The validity and effectiveness of the proposed controller are demonstrated on four-machine two-area test system that combines conventional synchronous generators and wind farms using simulations. Numerical results including modal analysis and time domain simulation are presented to illustrate the capabilities and contributions of the proposed controller to network dynamic performance. The main contributions of this paper are (i) the determination of the dominant interarea oscillations of the power systems, (ii) design of reduced order controllers for power damping oscillations, and (iii) increased renewable energy penetration with enhanced stability. Keywords-wind power penetration; doubly fed induction generator; power oscillation damping controller; small signal stabilityI.

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