Sharif Digital Repository

In this paper, a novel control approach for one-dimensional bilateral teleoperated nanomanipulation system is proposed. While manipulating objects with a nanomanipulator, real time visual feedback is not available. So, force feedback is used to compensate for the lack of visual information. Since nanometer scale forces are dominated by surface forces instead of inertial forces as in macro world, scaling of nanoforces is one of the major issues of teleoperation system. The Hertz elastic contact model is used to model the interactions between the slave robot and the environment. The proposed framework uses the simple proportional derivative control, i.e., the master and slave robots are... 

A modeling framework is proposed for complex chemical process networks. Concept such as passivity systems, thermodynamic function and graph theory are some important and applicable concept which seems to be useful for process network. The state is represented by energy, volume and mass inventories. The dynamic behavior of the process system is constrained so that all trajectories satisfy the first and second laws of thermodynamics. The concavity of the entropy function is used to define a storage function for passivity design. The proposed storage function is closely related to the Gibbs tangent plane condition. Stability analysis, pairing and controller design could be done by this new... 

In the present study, a new version of haptic devices is presented in which user’s hand is in contact with the device just while collision with virtual surface. In this system, the position of user’s finger can be traced by using a camera and the haptic device follows user’s finger at the distance of about two centimeters. While the haptic device approaches to the virtual surface, gradually reduces its speed and stops about two centimeters distant of virtual plane. Then user’s hand collides with the haptic device which is static. Greater fidelity, transparency, more stability and also no need to large actuators are of the advantages of this system. In this project, first we present a new... 

This dissertation is concened with the stability analysis and improvement in active power distribution grids. In active power grids, voltage stability challenges may occur due to the dynamic interactions among power electronic converters. In this research, power electronic converters are modeled in canonical form to investigate the effect of control loops on their impedance characteristics. The concept of dynamic interaction is explained from the impedance pint of view, which is the base of the stability criteria and imopedance coordinatioan. The concept of passivity is also explained and combined with the dynamic interaction to detect unstable modes from the DC bus impedance (Zbus)...