Anthropomorphic robotic hand has always been one of the interesting topics for researchers in recent decades due to its application range, including space exploration, medicine, military, etc. In this paper, a new plan is designed to drive exoskeleton fingers and by means of which the fingers can not only mimic human-like movements, but also be lightweight and portable. In this way, before implementation of the new plan, the anatomy of index finger and related kinematic were studied to give a hand to the extraction of angle relationships among distal, middle, and proximal phalanges. In upcoming step, theories, and mathematical relations about replacing sheaths and its influence on bending joints, based on the coupling mechanisms, were explained and applied clearly. Additionally, considering extracted relationships and equations in prior section, a new model of robotic finger with mentioned properties was simulated in MSC ADAMS software. In following step, after linking the software with Matlab, the results of the simulation and comparing them with human finger in the configuration and generation of humanoid movements were discussed. In the last step, according to simulation results, an example was constructed and presented, using a 3D printer in accordance with the proposed mechanism.
 

This article investigated design and construction of a 4-DOF delta parallel robot’s components and additionally inverse kinematics and kinematics control of the robot. The initial and final version of the robot based on existing needs, the addition of gearboxes due to the low torque of motors, and flange transformations to connect the gearbox to the robot's base were also discussed. In the following, by simulating the robot in MATLAB software, the integrity of the inverse kinematic equation of the robot was investigated. In the other part, the design of the kinematic control in the joint space was discussed and the results were plotted in the graphs for a z-direction. By designing a suitable robot controller, tracing the desired path and comparing its results with other controllers become possible. By designing a conveyor for the robot and equipping it with a camera, detecting the objects that the robot moves them become possible with image processing. For the purpose of picking and placing the objects, the robot's end effector is equipped with a controlled suction.  The results, through which the paths crossed, showed the designed PID controller for the robot was working correctly and the desired path was followed with small error.

Nowadays, the need of welding industry's to improve weld quality has led to the consideration of robotic welding. The use of articulated industrial robots for welding has many challenges. Because some robots do not have the capability of online error compensating of the seam track. Therefore, in order to remove the welding seam tracking error, the use of an auxiliary mechanism is proposed in this article. This mechanism is a table with 1-degree of freedom (dof), which produces a continuous motion in workpiece under the welding torch. The rotational motion of the motor is transformed into a translational motion of the workpiece by a ball-screw system, where this linear motion compensates the tracking error. Since in the welding process, relative motion accuracy of the workpiece and the welding torch is crucial, proper control of the interface table ensures the weld quality. In this paper, two different methods for controlling the table with 1-dof are studied. In the first method, due to the complexity of friction model of the ball-screw mechanism and the presence of nonlinear terms, this part of the model is considered as an external disturbance, and, then, a PID controller for the linear part is designed. In the second method, known as feedback linearization, a control law is designed for that the tracking error tends to zero by passing time. Throught a comparison between the simulation results, the second control method demonstrates better precision relating the first controller. While the error of PID controller equals to 3 mm and the second controller’s error does not go beyond 0.5 mm. At last, the experimental cell used for the robotic welding is introduced to evaluate the mentioned results.

Because of the fact that cable-driven parallel robot ​possess limited moment resisting/exerting capabilities and relatively small orientation workspaces, in this paper, a method for determination of optimal configuration of reconfigurable cable-driven parallel robots is presented to improve their performance. In such robots, actuators can move the cable attachment points on the base with respect to the motion of the end-effector in its trajectory. In the determined configuration, any external wrench on the end-effector can be balanced, using cable forces for all poses near to a pose of the robot. The largest wrench-closure circular zone centered at an arbitrary point of a trajectory for a given range of orientation around a reference orientation of the end-effector is computed. Taking the area of such zone into account and with the aim of enlarging them, the optimal configuration of the robot is determined. The optimal configuration is found by appropriately changing the position of the moving attachment points on the base of the robots. By applying this procedure on a number of points on a given trajectory iteratively, proper actuation schemes are obtained. In this paper, this method is utilized for reconfigurable planar cable-driven parallel robots and the quality of their actuation schemes is compared with the robots with fixed cable attachment points on

Parallel robots have a lot of compared to their counterparts, serial robots, such as higher accuracy, more load to weight ratio, and higher stiffness, which contribute to their various, and precise applications. Stiffness of the robot, as one of the most crucial parameters which should be considered in of the robot, the desired application. In this paper, an experimental study is investigated on evaluation of the robot’s stiffness and the errors corresponding to of the mechanism, which indicate the displacement of -effector of the robot with respect to external imposed forces. The aim of this paper is to evaluate the stiffness and the errors due to the softness behavior of the mechanism of a 3 degree of freedom (3-DoF) parallel robot; for this end, the amount of transfer of the final executor to the applied load is simulated. First, the 3-DoF decoupled robot is introduced and its features are expressed and the stiffness of the mechanism is modeled using Finite Element Method (FEM). Then, of the mechanism is determined in different positions of the end-effector by considering predefined boundary conditions. In order to evaluate the obtained model of the robots’ stiffness, a novel experimental setup is developed to measure the stiffness of the mechanism. By employing the setup, of the robot is measured in different conditions. Finally, the output results of the stiffness model are compared to the experimental tests. The results reveal that the 3-DoF decoupled parallel robot shows a proper stiffness behavior. Hence, it can be employed in various applications with high precision.

Determining a dynamic model for an underwater robot is of great importance in design of guidance and control system. Researchers always need a complete knowledge about hydrodynamic stability derivatives coefficients of vehicle with sufficient accuracy to design a successful control system for underwater vehicles. The selection of proper actuator in control system is important on the global performance of the system and the costs of the project. Usually, the effect of dynamic stability derivative coefficients is not considered in the design of actuators; therefore, in the present study, it is tried to investigate the effect of these coefficients in the design of actuators. For this purpose, firstly, the equations of motion for an underwater robot are presented. Then, hydrodynamic coefficients that contains static and dynamic coefficients are determined, using a rapid computational code and, then, the effect of hydrodynamic stability derivatives coefficients on the operational dynamic parameters of vehicle such as the bandwidth of the system dynamics and its role in the control system are considered. Finally, the selection of appropriate actuator for the underwater robot and the effects of natural frequency of actuators on the system performance are studied.
 

Spherical robots are the mobile robots with spherical shapes equipped to an internal drive mechanism that moves on the ground due to their external shell rolling. In this research, first, a pendulum spherical robot is modeled, then using the Lagrange method, dynamic equations of plane motion of robot on the non-flat surface are derived. Considering the scarcity of the number of operators relative to the number of degrees of freedom of the spherical robot, designing of a non-linear controller is performed based on feedback linearization techniques. Therefore, regarding non-confirm initial conditions on the trajectory, parametric uncertainty and disturbance torque on the robot, the performance of the system has been investigated. By selecting the appropriate rotation trajectory, the robot motion is simulated in MATLAB software and in following the pendulum rotation angle and actuating torque are obtained. The results indicate that the designed controller has proper and resistant performance in tracking selected trajectory for sphere shell rotation during moving on a non-flat surface.

In this paper, the design and construction of a new binary pneumatic actuated hyper-redundant manipulator is presented. The discretely actuated hyper-redundant manipulators have advantages such as wide workspace, the ability of obstacle avoidance and simple control. Despite of these advantages, few prototypes have been made so far, which each of them has some defects. These defects are small movement range, fairly high cost, and accelerated and impulsive motion. To solve these problems, the 3-revolute prismatic spherical parallel mechanisms (3-RPS) are used as modules in this paper. So the cost is reduced due to the lower number of legs. Also, the motion range has been increased by replacing the spherical joints with universal joints. The movements of the manipulator have been effectively more uniform and softer by using flow control valves on cylinders. Finally, several tests are conducted to determine how the manipulator moves and the results are presented.