Development of high performance servo drive/anti drive mechanism for backlash removal
Keywords: 1 Degree of freedom Platform, Backlash Removal, System Modelling. Abstract: In electromechanical drives, there is always a backlash between any pair of gears. Because of this, it is almost impossible to realize a high accuracy and high performance drive. However such drives are crucial in today’s modern electromechanical systems. A high performance drive/anti-drive servo mechanism is developed to eliminate the effect of backlash. The concept utilizes redundant unidirectional drives to assure positive coupling of gear meshes at all times. Based on this concept, a methodology for enumeration of admissible redundant-drive backlash free mechanism has been established. The angular displacement is achieved as a difference of two torques. These torques can be controlled by a high performance control system. A controller model will be designed to move a single degree of freedom platform up to a desired span with a payload.
Discrete Output-Prediction based Proportional Switching controller
This paper introduces a novel control law that is generic in nature and stabilizes linear and a class of non-linear systems. The parameters of the proposed controller give the same flexibility of tuning the transient response of a system as the standard PID does. The superiority of the Output-Prediction based Proportional Switching (OPPS) controller lies in the fact that it addresses the fundamental implementation problems of the PID such as integrator windup, high frequency gain of the derivative term and especially sacrifice of rise-time as system damping is further enhanced using the derivative term. Extensive simulation results are presented implementing OPPS on different linear and non-linear systems that show its generic nature and strength. Finally OPPS is implemented to stabilize a 2-DOF platform stabilization scheme and results are compared with those of a PID.
Fungal Biotransformations in Pharmaceutical Sciences
The regio- and stereoselective conversion of complex substrates represents one of the major advantage of microbial biotransformation. This chapter covers the biocatalytic capacities of fungi to derivatize bioactive small molecules, both from natural sources and from synthetic compounds. We focus particularly on sterol and taxane biotransformation. We also present examples at the interface of biotransformation and pathway engineering using recombinant organisms, with an emphasis on the production of lovastatin derivatives. Finally, we highlight selected studies on fungal xenometabolism which serves as a model to study the breakdown of drugs in mammals.