Sharif Digital Repository

Gimbal transmissions are non-linear direct transmissions and can be used in robotic arms replacing the traditional revolute joints. They offer potential advantages for critical cases such as joint space and task space singularities or where a different mechanical advantage is needed compared to what traditional revolute joints provide. This can be obtained by properly adjusting the different parameters of Gimbal joints used in different joints of the manipulator (such as their offset angle and/or chamfer angle). In this paper the concept of Gimbal mechanism as a joint is investigated. Then, as an example, Gimbal joints are used to replace the basic revolute joints of a 3-UPU parallel... 

This paper presents a modified sensor-based online method for mobile robot navigation generating paths in dynamic environments. The core of the navigation algorithm is based on the velocity obstacle avoidance method and the guidance-based tracking algorithm. A fuzzy decision maker is designed to combine the two mentioned algorithms intelligently. Hence the robot will be able to decide intelligently in various situations when facing the moving obstacles and moving target. A noble noise cancellation algorithm using Neural Network is designed to navigate the robot in an uncertain dynamic environment safely. The results show that the robot can track a moving target while maneuvering safely in... 

Neural networks have been applied very successfully in the identification and control of dynamic systems. The universal approximation capabilities of the multilayer perceptron have made it a popular choice for modeling nonlinear systems and for implementing general-purpose nonlinear controllers. In this paper we try to model and control the mass-spring-damper mechanism as a 1 DOF system using neural networks. The control architecture used in this paper is Model reference controller (MRC) as one of the popular neural network control architectures  

A semi-active controller-based neural network for a suspension system with magnetorheological (MR) dampers is presented and evaluated. An inverse neural network model (NIMR) is constructed to replicate the inverse dynamics of the MR damper. The typical control strategies are linear quadratic regulator (LQR) and linear quadratic gaussian (LQG) controllers with a clipped optimal control algorithm, while inherent time-delay and non-linear properties of MR damper lie in these strategies. LQR part of LQG controller is also designed to produce the optimal control force. The LQG controller and the NIMR models are linked to control the system. The effectiveness of the NIMR is illustrated and... 

Though wound healing process is well-researched, this area is poorly known. One reason is that all interactions have not been discovered, the main reason, though, is that the involved processes interact in a very complicated manner with nonlinear feedback. Such complex feedback mechanisms can be easily addressed by mathematical modeling. This paper contains a review of the mathematical modeling of cell interaction with extracellular matrix components during the process of dermal wound healing with focusing on remodeling phase. The models are of partial differential equation type and solved by numerical method  

Wound healing is a complex biological process dependent on multiple variables: tissue oxygenation, wound size, contamination, etc. Many of these factors depend on multiple factors themselves. Mechanisms for some interactions between these factors are still unknown but it is generally accepted that collagen synthesis, accumulation and organization are increased by mechanical stimuli, resulting in a forced healing process which improves mechanical properties of the damaged tissue. In this paper we focus on the neural networks and regard them as function approximators, and attempt to simulate remodeling phase of dermal wound healing process using neural networks as an intelligent technique  

Though wound healing process is well-researched, this area is poorly known. One reason is that all interactions have not been discovered, the main reason, though, is that the involved processes interact in a very complicated manner with nonlinear feedback. Such complex feedback mechanisms can be easily addressed by mathematical modeling. This paper contains a review of the mathematical modeling of cell interaction with extracellular matrix components during the process of dermal wound healing with focusing on remodeling phase. The models are of partial differential equation type and solved by finite element method  

Featuring a nonlinear novel design, Gimbal transmission, is a replacement for traditional robotic joints like gearboxes and revolute joints. This mechanism is one of the most recent types of nonlinear direct transmission (DT) methods in robots. As an alternative for traditional drive methodologies - herein called direct drive transmission (DD) methods, DT provides dynamic coupling and joint interaction attenuation while its capability to be adjusted for a desired task space point, smooth input-output characteristic, and varying reduction ratio lead to a desired force and motion behavior for the whole manipulator. In this paper, design optimization of a gimbal mechanism used as a replacement... 

Gimbal transmissions are non-linear direct transmissions and can be used in robotic arms replacing the traditional revolute joints. To investigate manipulability of robotic manipulators, the classical criterion of Manipulability Ellipsoid has been formulated. Thus by keeping a constant norm for robot joint torques vector, the effects of replacing some traditional revolute joints in robotic arms with Gimbal transmissions, have been analyzed. The results show that the magnitude of the maximum force applicable when employing Gimbal transmission can be considerably larger. Also, the joint angles in which this maximum occurs, can be adjusted, thanks to the behavior of Gimbal transmission. Two... 

This paper describes a neural network controller for autonomous underwater vehicles (AUVs). The designed online multilayer perceptron neural network (OMLPNN) calculates forces and moments in earth fixed frame to eliminate the tracking errors of AUVs whose dynamics are highly nonlinear and time varying. Another OMLPNN has been designed to generate an inverse model of AUV, which determine the appropriate propeller's speed and control surfaces' angles receiving the forces and moments in the body fixed frame. The designed approximation based neural network controller with the use of the backpropagation learning algorithm has advantages and robustness to control the highly nonlinear dynamics of... 

This paper will first describe predictor controllers when the proportional-integral-derivative (PID) controllers are inactive for procedures that have large delay time (LDT) in transfer stage. Therefore in those states, the predictor controllers are better than the PID controllers, then compares three types of predictor controllers. The value of these controller's parameters are obtained by trial and error method, so here an effort has been made to obtain these parameters by Ziegler-Nichols method. Eventually in this paper Ziegler-Nichols method has been described and finally, a PIP controller has been designed for a thermal system, which circulates hot air to keep the temperature of a... 

In this paper, the problem of obtaining the optimal trajectory of a Dual-Arm Cam-Lock (DACL) robot is addressed. The DACL robot is a reconfigurable manipulator consisting of two cooperative arms, which may act separately. These may also be cam-locked in each other in some links and thus lose some degrees of freedom while gaining higher structural stiffness. This will also decrease their workspace volume. It is aimed to obtain the optimal configuration of the robot and the optimal joint trajectories to minimize the consumed energy for following a specific task space path. The Pontryagin's Minimum Principle is utilized with a shooting method to resolve kinematic redundancy. Numerical examples... 

This paper first will describe @Home Mobile Robot and DC motors. In continuous, is designed a Direct current (DC) motor for special task due to specific speed diagram for considered robot. This robot wants to work in intermittent operation condition. Finally is done a speed control on a selected permanent magnet brushed DC motor using of Linear-Quadratic-Regulator (LQR), Linear-Quadratic-Gaussian (LQG) and Fuzzy logic controllers  

The Dual-Arm Cam-Lock (DACL) robot manipulators are reconfigurable arms formed by two parallel cooperative manipulators. Some of their joints may lock into each other. Therefore, the arms normally operate redundantly. However, when higher structural stiffness is needed these two arms can lock into each other in specific joints and loose some degrees of freedom. In this paper, the dynamics of the DACL robot is discussed and parametrically formulated. On the other hand, the criteria and implementation of genetic algorithm (GA) to optimize the configuration of DACL robot manipulators at a specific point with the objective to maximize the cooperatively applicable task-space force in a desired... 

Biological systems are highly nonlinear, and there is a significant amount of variability from one patient to another. A controller for drug infusion has to be able to achieve good performance for most of the potential patient population. These controllers are designed for the general population, as no knowledge is available before hand for each particular patient. This necessitates perforce an algorithm that will be able to compensate for the differences between individuals and external factors. Of the possibilities, fuzzy logic direct model reference adaptive control (DMRAC) is the choice for Insulin infusion control for diabetes type I as results presented herein. Safety and robustness... 

In this paper obtaining the optimal configuration of the dual-arm cam-lock (DACL) robot at a specific point is addressed. The objective is to optimize the applicable task-space force in a desired direction. The DACL robot is a reconfigurable manipulator formed by two parallel cooperative arms. The arms normally operate redundantly but when needed, they can lock into each other in certain joints in order to achieve a higher stiffness, while losing some degrees of freedom. Furthermore, the dynamics of the DACL robot is discussed and parametrically formulated. Considering the geometrical constraints at a given point in the robot's workspace, the optimum configuration for maximizing the... 

The Dual-Arm Cam-Lock robot is a reconfigurable manipulator formed by two parallel cooperative arms. Based on the application, these arms may loose some degrees of freedom by locking into each other. However, they are considered as redundant arms when operating without any locked joints/links. In this paper, a method is introduced to find the optimal configuration of this manipulator. The objective is to find the configuration in which maximum cooperative force is exerted to an object in a specific direction. The dynamics of the robot is parametrically formulated for different configurations, and by considering the geometrical constraints optimization is performed using fine-mesh and genetic... 

Cupric oxide (CuO) nanostructures are grown on fluorine doped tin oxide (FTO) coated glass substrate using aqueous solution approach. The concentration of precursor's solution has significant impact on morphology of CuO nanostructure. By varying concentration of precursor, the growth of two different morphologies (oriented nanosheets and nanoleaves) is achieved. X-ray diffraction pattern and X-ray photoelectron spectroscopy reveals formation of pure CuO crystalline phase. Mott-Schottky characteristic confirms the p-type semiconducting nature. Ultrathin structures of nanoleaves lead to higher light trapping and light absorption in visible-NIR region. The nanoleaves film has lower bandgap in... 

Cooperative systems have been extensively investigated in literature. Herein the criteria and implementation for finding the optimal configuration of the Dual-Arm Cam-Lock (DACL) robot manipulators at a specific point with the objective to optimize the applicable task-space force in a desired direction are addressed. The DACL robot manipulators are reconfigurable arms formed by two parallel cooperative manipulators. Some of their joints may lock into each other. Therefore, the arms normally operate redundantly. However, when higher structural stiffness is needed these two arms can lock into each other in specific joints and loose some degrees of freedom. The dynamics of the DACL robot is...