اہل بدعت سے تحدیث و سماع کا حکم: علامہ احمد شاکر کی آراء کا اختصاصی مطالعہ

Allama Ahmad Shakir was a great researcher and has a good command on religious literatures and studies. In his era, he took a great place among the scholars as a specialist in hadith, Islamic jurisprudence, Quranic interpretation, history & principals of aforementioned Subjecta. Now, he is recognized as an authority on principalities of sciences of hadith and jurisprudence. He discussed in his books regarding Sciences of hadith about narrators of hadith which are called ahl e bid‘at and the status of their Ahad?th. Because, there is a huge conflict between many principalities in perspective of accepting their Ahad?th or rejecting them. In this article, based an analytical study, some of his major and innovent concepts and justified principals about ahl e bid‘at are discussed which he had presented in his books or shows his research methodologies in different books with a special study on al-musnad by Imam Ahmad Bin Hanbal (r.a). The research shows his viewpoints regarding this kind of narrators that they are, with some conditions, acceptable and their Ahad?th are also should be narrated. Although, some ancient scholars do not allow with primarily conditions, which are described in this study along with their status & conditions.

Modeling and Control for Trajectory Tracking and Multi-Robot Formation of Nonholonomic Wheeled Mobile Robots

Wheeled mobile robots (WMRs) are difficult to stabilize and control due to nonholonomic constraints. The complexity of control increases when there is a need to control a group of WMRs in a specific formation. The research described in the thesis concerns the modeling, control and formation of nonholonomic WMRs for trajectory tracking. In particular, this research work proposes novel control approaches for WMR trajectory tracking and formation control of multi-robot system. The kinematic model of WMR is studied, and then various kinematic controllers have been implemented to identify suitable kinematic controller for WMR trajectory tracking using performance based simulation results. The trajectory tracking problem is extended by including the dynamic model of WMR along with the model uncertainties and disturbances. A novel adaptive sliding mode state feedback control law is proposed for trajectory tracking, which includes the integral action and hence it is able to remove the steady state errors and reject the external disturbances. The proposed adaptive dynamic controller uses velocities as input commands, which is more practical and appropriate from the view-point of real-time application. The proposed dynamic state feedback controller requires all the states specially WMR linear and angular velocities. Therefore, the trajectory tracking control problem is addressed again in the context of output feedback control for WMR. The tracking formulation is defined with the high gain observer to estimate the linear and angular velocities. It is shown that using high gain observer and a globally bounded state feedback stabilizing controller, the close-loop system performance can be recovered in the presence of un-modeled dynamics. The formation control problem of vi multi-robot system is addressed using leader-follower formation approach. The kinematic model of the leader-follower formation is developed in the presence of uncertainties and disturbances. It is followed by an integral terminal sliding mode control for robust formation control and finite-time convergence. The proposed controller eliminates the requirement of leader’s velocity information which increases the reliability of multi-robot system. Obstacle detection and collision avoidance are incorporated to maintain the desired formation in the presence of obstacles. The stability analyses is carried out using Lyapunov stability theory. The performances are verified and validated using time invariant and time varying trajectories.