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Shi'a jurists, view based on what narrate, the Prophet's household (p.u.t) make between the apostate born to a Muslim and the one born to a non- Muslim and then became a Muslim. The point of the distinction is that the former (murtadd fitri) is not asked to repent and the punishment (hadd) will be imposed on him while the latter (murtadd milli), is asked by the judge to repent and if he did, the punishment will be lifted. Now, if murtadd fitri happened to repent before introducing evidence – without duress and coercion – would it be of any help? Most of the jurists believe that this repentance is of no avail and it will not lift the legal consequences such as execution, separation from espouse, division of property among heirs. In this paper, I will first examine the evidence of such precept to conclude the if murtad fitri, repents before the introduction of evidence, at least the penalty (hadd) for apostasy will be lifted and the authorities fall short of covering this case. Then the issue of Istitabat (asking repentance) of apostate and its duration will be briefly discussed.

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The inertial forces and moments, due to the motion of robotic arms installed on a mobile base, lead to reaction forces on the moving base which may cause its unexpected motion. In this article, a method of designing a path of motion in the Cartesian space between the initial and final positions is presented which guarantees no reaction on the moving base. To this end, developing the system dynamics model, the moment equations are derived. Based on the conservation of momentum in the absence of any external force and moments, the angular motion due to the motion of robotic arms is solved. Then, based on the definition of reaction null-space map for dynamic coupling matrix, the joint speeds are projected to the reaction null-space, to obtain the joint speeds in this space. Next, using numerical integration of the obtained joint rates, the motion in the joint space with no reaction on the base is obtained. Therefore, motion of robotic arms according to these joint specifications, the total momentum of the system remains zero, and due to no reaction forces applied on the moving base, its position and attitude remains unchanged.

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Tractor-trailer wheeled mobile robot (TTWMR) is a robotic system that consists of a tractor module towing a trailer. Trajectory tracking is one of the challenging problems which is focused in the context of wheeled mobile robots (WMRs) that has been discussed in this paper. First, kinematic equations of TTWMR are obtained. Then, reference trajectories for tracking problem are produced. Subsequently, an output feedback kinematic control law and a dynamic Fuzzy Sliding Mode Control (FSMC) are designed for the TTWMR. The proposed controller steer the TTWMR asymptotically follow reference trajectories. Finally, experimental results of the designed controller on an experimental setup and comparison results are presented. Obtained results show the effectiveness of the proposed controller.

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In this paper, trajectory tracking control of a wheeled mobile robot is analyzed. Wheeled mobile robot is a nonlinear system. This system including three generalized coordinates (x,y,ϕ), and a nonholonomic constraint. First, system kinematic and dynamic equations are obtained. A non-model-based control algorithm using PD-action filtered errors has been used in order to control the wheeled mobile robot. Non-model-based controllers are always more appropriate than model-based algorithms due to independency from dynamic models, lower computational costs and also robustness to uncertainties. Asymptotic stability of the closed loop system for trajectory tracking control of wheeled mobile robot has been investigated using appropriate Lyapunov function and also Barbalat’s lemma method. Finally, in order to show the effectiveness of the proposed approach simulation and experimental results have been presented. Obtained results show that without requiring a priori knowledge of plant dynamics, and with reduced computational burden, the tracking performance of the presented algorithm is quite satisfactory. Therefore, the proposed control algorithm is well suited to most industrial applications where simple efficient algorithms are more appropriate than complicated theoretical ones with massive computational burden.

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Accuracy and numerical calculation time are the two main challenges of continuum robots dynamics modeling. In fact, the numerical calculation times of exact models are so long, that they are not practical in applications such as real-time control. This paper presents a new method for dynamics modeling of continuum robot backbones. In this method, the backbone shape is considered as an arbitrary number of constant-curvature (circular arc) elements, and the dynamics model is derived using Lagrange energy methods. First, kinetics and kinematics of one element are derived. Then, the robot kinematics is derived, as a series of such elements. Finally, the robot dynamics model is derived, using Euler-Lagrange method. This paper is focused on dynamics of the flexible body of continuum robots, and the proposed model is independent of actuation systems. Besides, the numerical singularity of the constant-curvature elements is avoided, which occurs when an element is straight. The model is validated using experimental results. Comparison of simulation and experimental results shows the accuracy of the proposed method on dynamics modeling. Furthermore, the calculation time of the model is short enough to make it practical for applications such as real-time control.

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In this article, the significance of utilizing active toe joints in biped robots feet is examined. The main goal of this research is to employ active toe joints and heels to improve gait performance from two points of view: actuating torques of knee joints and total consumed energy. Considering the effectiveness of toes and heels in walking, a new walking pattern is fully addressed and compared with another walking pattern which does not exploit toes and heels. In order to develop a verified dynamics model for considered humanoid robot with 22 DoFs, two analytical methods i.e. Lagrange and Kane are adopted and the obtained results are compared. To reduce calculation burden, an iterative method for dynamics model development is proposed, based on Kane approach. Furthermore, to verify the obtained ground reaction forces and moments, ZMP is computed and compared using two methods. In the procedure of gait planning, first the pelvis trajectory is planned. Then, the feet trajectory planning process is done. After designing trajectory in task space, all joint trajectories except the trajectories of toes are obtained, using closed-form inverse kinematics solution. Toe joints trajectories are planned separately, considering the sole trajectories. Consequently, the significant parameters in gait planning are considered as design variables in optimization procedure in order to reduce the maximum torque of knees and total consumed energy as cost functions. Finally, it is demonstrated that which walking pattern is highly appropriate for walking with large step length on flat terrain, under joint torque and velocity limitations.

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Trajectory tracking is one of the main control problems in the context of Wheeled Mobile Robots (WMRs). Besides, control of underactuated systems possesses a particular complexity and importance; so it has been focused by many researchers in recent years. In this paper, these two important control subjects are discussed regarding a Tractor-Trailer Wheeled Mobile Robot (TTWMR); which includes a differential drive wheeled mobile robot towing a passive spherical wheeled trailer. The use of spherical wheels instead of standard wheels in trailer makes the robot highly underactuated with severe nonlinearities. Spherical wheels are used for the trailer to increase robots’ maneuverability. In fact, standard wheels create nonholonomic constraints by means of pure rolling and nonslip conditions, and reduce robot maneuverability. In this paper, after introducing the robot, kinematics and kinetics models are obtained, and combined as the dynamics model. Then, based on physical intuition a new controller is developed for the robot, named as Lyapaunov-PID control algorithm. Then, singularity avoidance of the proposed algorithm is discussed and the stability of the algorithm is discussed. Simulation results reveal the suitable performance of the proposed algorithm. Finally, experimental implementation results are presented which verify the simulation results.

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Maintaining and restoring robot balance in the presence of external disturbances is a significant capability for a quadruped robot. This is due the fact that these robots move over uneven terrains which may be themselves the sources of the disturbances. In this article, the balance recovery problem of a quadruped robot after an external disturbance will be investigated. To this end, as first stage, the equations of motion of a whole-body model of a robot and also a constraint elimination method will be proposed. In order to recover robot balance, the desired accelerations will be computed based on the concepts of a PD controller and by using the desired velocities and the positions of the main body. However, these accelerations maybe lead to slip stance feet or lose robot stability. Therefore, an optimization problem will be defined to calculate the admissible accelerations and the contact forces simultaneously. The optimal regulation of the contact forces will be done to distribute the contact forces among all stance legs to avoid feet slippage. Since the stability and the slippage avoidance conditions are formulated as linear constraints, the optimization can be solved as a linear constrained least squares error. To evaluate the effectiveness of the proposed algorithm, it will be examined on a quadruped robot in the simulation in two different case studies: in standing situation and walking gait. Finally, obtained results will be discussed.

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Cable-Driven Parallel Robot has many advantages. However, the problems of cable collision between each other and environment, the lacks proper structure and non-positive cable tension prevent the spread of them. Therefore, connecting a serial manipulator to mobile platform improve the ability to object manipulation. This paper investigates the multi-objective optimization structure design and comparative study of spatial constrained and suspended cable-driven parallel robot. By install serial manipulators possess a full hybrid robot’s features. The workspace volume, kinematic stiffness and sensitivity are three sets of optimization criteria. The workspace volume calculated by a novel approach of combination constraints as prevent cables collisions with each other, cable collision with moving platform, uncontrollability and singularity of the robot. First, examine range of the forces and torque reaction of the serial manipulator to moving platform. Then, the evolutionary optimization genetic algorithm use for the multi-objective optimization of constrained and suspended spatial cable-driven parallel robot structure to achieve proper Pareto front confrontation. The Pareto front reconciliation of these three criteria will be discussed. The constrained and suspended optimize by same criteria will compare in the same conditions. It is verified that the constrained structure significantly reduced actuation energy for manipulate a serial robot, supply greater workspace and manipulability. The result of this study used for manufacturing and development of a prototype spatial cable-driven parallel robot (RoboCab).

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A solar-powered robot is a mobile robot powered completely or significantly by direct solar energy. The sun's energy is converted into electric energy by solar panels mounted on the robot. These solar panels are required to be light, because of the important demands for low-energy consumption. As a result of the flexibility of elements of the panels, undesirable low-frequency vibration may occur when the robot moves on a rough terrain. In this paper, a new method for stabilization of solar panels vibration base on trajectory planning for articulated mobile robot is presented. The dynamics of solar panels attached to the robot is derived using Kane’s method. The attitude and configuration of a rover as a function of the terrain on which it moves is determined using inverse kinematics of the robot. The attitude and configuration of a rover is required to approximate the domain of vibration by derived dynamics equations. Base on this approximation, a trajectory planning algorithm is presented that can reduce vibration without significant decrease in the velocity of the robot. The proposed method is simulated for a six-wheeled mobile robot with rocker-bogie structure The obtained results show that the algorithm stable the domain of vibration in allowable area and do not decrease the velocity of the robot significantly.

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In this paper, dynamic modeling, optimal path planning and control scheme on a redundant parallel cable robot is presented. Path planning in parallel robots necessitates the consideration of robot’s kinematics to discern the singularities in the workspace. Also, dynamics analysis is required to consider actuation constraints. To this end, kinematics and dynamics of cable driven redundant parallel robot is derived. In this modeling, cables are assumed to be rigid with negligible mass and hence, tension and sagging along the cable are neglected. Next, a sampling-based algorithm upon rapidly-exploring random tree is developed to increase the convergence rate. In this scheme, distance, epochs and safety are considered as optimization constraints. To evaluate the performance of the proposed algorithm in collision avoidance, a number of obstacles have been considered too. Tracking of the planned path has been handled using a feed-forward controller in the presence of obstacles. Regarding the redundancy feature of robot, a redundancy resolution scheme is considered for optimal force distribution. Path planning and control algorithms are implemented on the RoboCab (ARAS Lab.) and experimental results reveal the efficiency of the proposed schemes.

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Wearable robots are robots which are used for rehabilitation or augmentation by human. Recently, there has been an increasing interest in the development of wearable devices to assist elderly as well as patients, soldiers and many other persons for movement assistance and power augmentation. On the other hand, a realization of wearable robot which has the same degree of freedom of a human is not easy from considerations about a size and weight of device. This study is about a lower limb assist robot that consist of just an actuator on each of legs. In this paper after a brief review on wearable robots and their applications, a suitable design of robot which is named RoboWalk presented with inspiring from Honda weight compensation system. In the following kinematics and dynamics modeling of system presents with using of denavit-hartenberg parameters and validates with ADAMS software results. Results with high accuracy has been achieved. It’s necessary to evaluate main foundation of design of robot which is an assistant force in the direction of foot reaction force that has been achieved with the accuracy of 0.02 radians. finally effect of change in user’s weight, position of center of mass and friction of walking assistant robot component is examined in this study.

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The increasing consumption of non-renewable energy sources such as oil and gas and reducing their reserves make it more necessary to pay attention to clean and renewable resources. In this situation, wind energy is known as one of the safest options for generating electrical energy. In this study, with the aim of evaluating the impact of climate change on the economic and environmental characteristics of wind turbines, numerical modeling was developed in MATLAB software. In order to evaluate the effects of the mentioned parameters as a case study, this numerical modeling for the parameters expressed in 4 cities of Iran, including Rasht, Tehran, Abadan, and Sanandaj, as the representatives of the main climates of Iran has been analyzed. According to the results of the economic point of view, which represents the Levelized cost of the energy production unit, Abadan was recognized as the most economical case with a   Levelized cost of  1.04 $ per kilowatt-hour of energy. Also, the environmental aspect of the analysis, which is based on the life cycle assessment method, considering the amount of carbon dioxide produced during the system life cycle and its pricing based on penalty policies, Rasht with a mild climate and emissions of 156 kg. Carbon dioxide per year and the lowest fine cost (annual cost $ 2.26) showed the most suitable option among other cities.

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One of the problems in the experiment of breakup cryogenic liquid jet is the state of discharged cryogenic liquid jet from injector. In some applications, it is necessary jet to be in the sub-cooled condition. However, at atmospheric condition, the discharged cryogenic liquid jet becomes two-phase. In the present article, the methods for sub-cooling of the liquid nitrogen jet are investigated and a simple method to achieve this goal is used. With this method, which is based on holding at low pressure, a sub-cooled liquid nitrogen jet with a temperature of about 7 K lower than the saturation temperature was obtained. Then, the behavior of the liquid nitrogen jet at high pressure and atmospheric pressure is evaluated. High speed camera was used to observe the behavior of the jet. The speed of liquid jet is changed from 12 m/s to 34 m/s according to the Reynolds number from 90000 to 260000. When the liquid nitrogen jet is discharged into the environment under standard conditions, the jet becomes two-phase and expands. The larger the injector pressure difference, the greater the expansion of the jet; So that in the pressure difference of 6 and 13 bar, the diameter of the jet is 1.5 and 3.3 times the diameter of the injector, respectively. In the test speed range, under the conditions provided for the liquid and the environment, the breakup of the sub-cooled liquid jet leads to the production of very small droplets that are consistent with the expectation of such a liquid.