Sharif Digital Repository

Nowadays, due to the advancement of robotic technologies and development of industrial robots, the robot manipulators are widely used for automation of various manufacturing processes, such as finishing processes. In these applications, the contact has to be made between robot end-effector and environment. Therefore, control of interaction force in the constrained manipulators is an important demand. On the other hand, due to use of gear box and belts for energy transmission in robot joints, robot manipulators have flexible joints. The vibration, generated due to the interaction force and robot joint flexibility, can deteriorate surface roughness in automated finishing processes. In order to... 

Haptic Interfaces have been used as cooperative systems to reproduce and simulate human actions. The Haptic Interface (HI) can be used as a tool capable of interacting dynamically with the operator using haptic technology. By controlling the haptic interface and constraining it to move through the desired trajectory which is required for most of the training systems such as Hand Writing Learning System, Minimally Invasive Surgical Simulation, virtual welding training and gaming applications the users can easily interact with virtual environment through the sense of touch. Haptic device application in virtual handwriting training was investigated in this thesis. Two different modes of... 

In the present study, a new version of haptic devices is presented in which user’s hand is in contact with the device just while collision with virtual surface. In this system, the position of user’s finger can be traced by using a camera and the haptic device follows user’s finger at the distance of about two centimeters. While the haptic device approaches to the virtual surface, gradually reduces its speed and stops about two centimeters distant of virtual plane. Then user’s hand collides with the haptic device which is static. Greater fidelity, transparency, more stability and also no need to large actuators are of the advantages of this system. In this project, first we present a new... 

Some of the most usual problems in rehabilitation are ankle joint disabilities which are caused by stroke or damages like ankle twist and disrupt the movement activities. So rehabilitation of this joint which has important role in daily activities like walking is of high importance.
The aim of this research is design of an unwearable robot for rehabilitation of ankle. After the study of several different mechanisms, this robot was designed based on a 2 DOF mechanism named “Agile Eye”. Based on the mechanism and parametrical analysis, final design of this robot was drafted using optimization method. Next, the musculoskeletal model of lower limb was created in MATLAB and by using this... 

Nowadays, worm robots are widely designed and manufactured for different applications. The most common applications for these types of robots can be mentioned as maintenance of small pipes and medical purposes in biological vessels such as the lungs, intestines, urethra and blood vessels. The robot must be small, controllable, safe, reliable, energy efficient, and must be able to crawl both, forward and backward. Different worm robots have been developed and manufactured, for different purposes such as, medical and industrial applications. Most of these projects are typically designed with three or more actuators for control of the distance between cells and the clamps.The results of using... 

Hexapod Robots give us the ability to study walking robots without facing problems such as stability. It has a great deal of exibility in movement even if some legs become malfunctioned or face some diculties. Control of legged robots compared to other kind of locomotions is di- cult and requires fairly heavy on-line computations to be done in real time. Therefore, a machine-learning solution may be more convenient in such prob- lems. One method of machine-learning which is used for legged robots with outstanding potential is Reinforcement Learning (RL). RL is a promising ap- proach for achieving complex robots control in dynamic environments. RL techniques are interesting subjects in... 

Due to diversity in amputation possibilities, this thesis focuses on the specific case of ring finger amputation with some amount of stomp remaining. The goal is to design a robotic finger as a prosthetic, which its flexion and extension (position control) are instructed from an armband. The armband is equipped with 8 force sensors to detect volume variations in patient’s forearm. Its embedded microcontroller processes signals taken from these sensors, and using machine learning techniques (K-Nearest Regressor), decides on a specific angle for the finger. This angle value updates constantly, and using a flex sensor and a DC motor in finger, the desired flexion/extension is performed.... 

It is so essential to study a safe dynamics of agricultural mechanical equipment during duty stroke, plus getting a rich information about the nature of the soil under processing and in many cases there are associated simultaneous problems, so the main aim of this study is to create a safe working conditions for such specific equipment to extend their life time span as possible as it could. This study will predict an un-usual working circumstances for agricultural tools including plough of course depending on some automated technologies with fast response supported by smooth working conditions. Simply, the proposed Investigative system consists of a linear potentiometric element with... 

In this research, the problem of path planning for simple robots is studied. The robot used in this study is a robot that can only detect the order of discontinuities in depth information (gaps). Former problems that have been studied so far for this type of robot are path planning and searching in street polygons. Street polygons are a type of simple polygons such that if a robot starts from a specific starting point on the street, pointing to the end of the street at another specific point, it has seen the whole area of the polygon. The main purpose of this research is to study the environment features and finding the algorithms for path planning in streets in general modes including... 

In this study, we create an evolution function that assesses prosthetic hands in terms of their ability to grasp various objects like a human hand. It is required to evaluate the reachable workspace of prosthetic hands and grasp ability to assess it completely. The first one can be done by using forward kinematics. The Volume of the Grasp Wrench space, one of the grasp qualities indexes, is used to measure the second one. Randomization and grasp taxonomy are used to generalize the grasp quality to indicate the prosthetic hand functionality. Afterward, the created evaluation function is used to specify the importance of each finger and DOF. The results show that the most significant finger is...