Farhad Aghili

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Fig. 7. Mean distance between the desired image points and the actual image points at 26 intermediate configurations. The extra point represented for = 1 corresponds to the small error for the final desired image added after the final planned image. Fig. 8. Location of the robot end-effector frame at 26 intermediate configurations , for experiments 1(More)
— This paper focuses on the guidance of a robot manipulator to capture a tumbling satellite and then bring it to state of rest (detumbling). First, a coordination control for combined system of the space robot and the target satellite, which acts as the manipulator payload, is presented so that the robot tracks the optimal path while regulating the attitude(More)
This paper addresses the dynamics and control of direct drive robots with positive joint torque feedback. We analytically derive the system dynamics in closed form. Even though it is coupled and nonlinear in general , it is substantially simpler than the robot link dynamics. We also derive conditions on the robot conng-uration which result in linear(More)
—Most studies on adaptive coordination of multi-robot systems assume exact knowledge of system kinematics and deal only with dynamic uncertainties. However, many industrial applications involve tasks in which a multi-robot system interacts with geometrically unknown environments. In this paper, we consider a multi-robot system grasping a rigid object in(More)
—Positive joint torque feedback (JTF) can compensate the detrimental effects of load torques on position tracking performance. However, with (real world) nonideal torque sources, simple unity gain positive torque feedback can actually deteriorate the performance, or even result in instability. In this work, a new joint torque feedback approach is proposed(More)
—A new torque control strategy for brushless motors is presented, which results in minimum torque ripple and copper losses. The motor model assumes linear magnetics, but contains a current limit which can delimit the onset of magnetic saturation , or be the motor amplifier current limit, whichever is reached first. The control problem is formulated and(More)
—This paper presents a new model for torque generation of permanent-magnet synchronous motors and their control based on Fourier coefficients. A new commutation strategy delivers ripple-free torque and simultaneously minimizes copper losses for the case when the motor's servo amplifier dynamics are negligible. However, multipole motors give rise to high(More)
The open-loop torque control of synchronous motors with minimum torque ripple and minimum copper losses is presented. The control problem is viewed as an optimization problem for the nonlinear mapping from desired torque and position to the motor's phase currents. The performance of the controller to produce virtually ripple-free torque and to enhance the(More)
A new torque control strategy for brushless motors with minimum torque ripple and minimum copper losses while maintaining the phase currents under magnetic (or current) saturation is presented. The optimal control { a nonlinear map from desired torque and position to the motor's phase currents { is the closed form solution to a quadratic programming(More)