Fault-tolerant scheme for robotic manipulator -Nonlinear robust back-stepping control with friction compensation

Emerging applications of autonomous robots requiring stability and reliability cannot afford component failure to achieve operational objectives. Hence, identification and countermeasure of a fault is of utmost importance in mechatronics community. This research proposes a Fault-tolerant control (FTC) for a robot manipulator, which is based on a hybrid control scheme that uses an observer as well as a hardware redundancy strategy to improve the performance and efficiency in the presence of actuator and sensor faults. Considering a five Degree of Freedom (DoF) robotic manipulator, a dynamic LuGre friction model is derived which forms the basis for design of control law. For actuator's and sensor's FTC, an adaptive back-stepping methodology is used for fault estimation and the nominal control law is used for the controller reconfiguration and observer is designed. Fault detection is accomplished by comparing the actual and observed states, pursued by fault tolerant method using redundant sensors. The results affirm the effectiveness of the proposed FTC strategy with model-based friction compensation. Improved tracking performance as well robustness in the presence of friction and fault demonstrate the efficiency of the proposed control approach

Is Innovation in Pakistan Driven by Specialisation or Diversity?

Innovation is among the main drivers of industrial development leading to economic growth. However, the question triggers that what drives innovation? Is innovation driven by specialisation or diversification? The literature has supported both, the specialisation and diversification as driver of innovation. Therefore, the purpose of this paper is to explore the determinants of innovation in Pakistan with a special emphasis on specialisation and diversity. The analysis is based on the cross sectional data set of 784 firms across 13 different cities of Pakistan, i.e. Investment Climate Survey (ICS) 2007, compiled by the World Bank Enterprise Group. Our findings have showed the positive relation between innovation and diversity i.e. diversity is conducive to innovation. On the other hand, specialisation has a negative effect i.e. it hinders innovation in cities of Pakistan. JEL Classification: C21, C25, O31, O32 Keywords: Innovation, Specialisation, Diversity, Logistic Regressio