Sharif Digital Repository

Many workers and soldiers suffer from musculoskeletal problems due to carrying heavy loads. Using exoskeleton robots which are designed for power augmentation can be effective in preventing these disorders. Due to the interaction of these robots with human, it is necessary to design an appropriate control system for these robots, therefore, the aim of this research is to design a predictive nonlinear control system for a three degrees of freedom lower-limb Exoskeleton robot, in order to improve the performance of the robot, follow trajectory of human joints and reduce the interaction forces between human and the robot during the squatting activity. Multi-stage model predictive controller... 

The reflective optical rotary encoders are used greatly in automation systems for speed and position measurements. Their approach of reading code as pulses which results in position and speed information is very similar to what a CD-ROM driver performs to read the saved data as pits and lands on the compact disc data layer. Moreover, the micron size of pits and lands in compact disc promise a high-resolution, and low cost rotary encoder based on CD-ROM technology. In this thesis, two concepts of length coding and hybrid incremental-absolute coded discs are proposed. To verify the implementation of these concepts, the rotary encoder set based on CD-ROM technology is designed and tested. It... 

There is many sources of uncertainty in the power plants such as continuous changes of the ambient temperature and the climate condition. The controller of the boiler-turbine unite should be robust against uncertainties and overcome the changes in the operating condition. In this regard, a robust adaptive variable structure control scheme (RAVCS) is proposed to control a nonlinear multi-input multi-output (MIMO) model of industrial boiler-turbine unite, in the presence of unknown parameters and bounded uncertainties as well as external disturbances. Moreover, a robust controller based on and in the presence of rational deviation in parameters, is designed. To investigate the zero... 

In this thesis, modeling and dynamic analysis of a micro-robot motion in stick-slip-jump mode are studied. Stick-slip is one of the more common principles of locomotion for micro-robots. Stick-slip locomotion relies on friction, and requires the robot to continuously maintain contact with the substrate. By increasing the actuation force on the micro-robot (i.e. by increasing the input voltage amplitude or frequency), the micro-robot losses contact with the substrate, and the stick-slip principle is no longer valid. Under this condition, instead of the stick-slip mode, a combination of stick-slip motion and jumps governs the locomotion. We refer to this as stick-slip-jump locomotion. In... 

The control approaches in Exoskeletons are different from Autonomous robot. Because the Exoskeletons are in connection and interaction with the user. On the other hand they can use the wearer’s abilities such as intelligence, sensory organs, self-control and etc. Therefore, one of the most important parts of exoskeletons control algorithms is its interaction with the user. This part should recognize the goal and purpose of the wearer such as stopping, walking start, change in stepping and direction and etc. properly. Utilizing these algorithms properly, one can reduce the muscle activities and energy consumption up to 20 percent [1]. This investigations demonstrate the importance of the... 

The main goal of this project is to design and implement an Endoscopic Sinus Surgery Simulator using a nonlinear model relating the force and displacement of the surgery tool interacting with the virtual sinus tissue. This model approximately matches the force-displacement data attained from the experiments conducted on the real sinus tissues. To simulate the behavior of the sinus tissue in a virtual environment, a haptic device is utilized which imitates the behavior of the surgery tool interacting with the tissue model. The haptic device in this project is a Falcon Robot. Because of the uncertainties in the parameters of the robot and the operator’s hand model (which is considered in the... 

No one bears thinking about undergoing a surgery by an unexpirienced surgeon, the consideration of which implies the prominence of effective surgical trainings. The advent of utilizing haptic interfaces as a novelty in this field has led to a more promising surgery education. These haptic interfaces consist of three communicating parts namely: operator’s hand, haptic robot, and tissue virtual environment. Design and implementation of a proper controller in order to stabilize the haptic interface during surgery simulation, with acceptable transparency, is still novel an otherwise challenging research field. In this thesis we consider an appropriate nonlinear model for both virtual tissue as... 

Due to small size, flexibility, and low cost of manufacturing, micorobots are potentially suitable for implementation in a broad range of applications. Control and inspection, medical utilities, manufacturing and micromanipulation of small-sized devices with nano-metric precisions, and precise measurements are some of the most important applications of microrobots. Mobile microrobots are one of the significant divisions of microrobots that are capable of movement with small steps and possess a motion range of at least several times the robot’s body length. In this project, Modulated Friction Inertial Drive (MFID) is utilized as a mechanism for creating a mobile microrobot. The micorobot is... 

Laparoscopic surgery which is categorized under Minimal Invasive Surgery, has many advantages over conventional open surgery. Despite the beneficial effect of this method on patients, surgeons suffer difficulties in utilizing the method. Robotic surgery has been constituted as the answer to remove the difficulties yet retain the advantages.
In the so-called robotic surgery, the tool is handed to a robotic arm, i.e., the slave robot, which is installed and positioned at the bed side. The surgeon sits before a comfortable console and uses a joystick-like robot, i.e., the master robot, to manipulate the slave robot. The vision is also provided by a robotic camera holder and shown in a... 

Nowadays, fuel optimum used in engines is an important matter. To achieve this aim, we need to tune engine. The big companies have paid attention to these cases. Because of it, there are strict standard in the world and in other side the internal combustion engine is very common.
In the internal combustion engine after cylinder, the gas inter to an encasement which is called exhaust manifold. In the other hand, exhaust manifold is in upstairs of turbine and waste-gate in turbocharged SI engines. To control fuel used and descries the amount of emissions, exhaust manifold pressure is very important. In the other hand, monitoring of exhaust manifold pressure can use for fault detection of... 

Proper operation of a spark ignition engine is required by comfort demands of a vehicle driver and governmental legislations. Therefore it is essential to monitor, within an online technique, the engine and detect any fault which disrupts its operation. The gas exchange path (including the intake and exhaust subsystems) is an important part of turbocharged engines responsible for accurate control of both engine power and emissions. Monitoring the path for fault detection and isolation (FDI) has been always demanded due to many failures it may face since the turbocharger exasperates the harsh working conditions for components involved in the path. This paper presents a novel model-based... 

Nowadays, Automation and Robots have many industrial and non-industrial applications. One of the most important of Robotic applications in industries for speed increasing, is utilizing them for packing procedures on production lines. Speed and accuracy enhancement, low-error repeatability, and cost reduction are benefits if using robots. Delta robot, is one of the parallel robots which is consists of three arms each connected to universal joints at the base and can reach high speeds.Delta robot can be optimized in 1. Performance speed, 2.accuracy, 3. Maximum payload, 4. Workspace and dexterious workspace and 5. Costs reduction. Since it’s not possible to fully optimize all goals... 

In this paper, controlling the cutting force of an end-milling process using a supervisory fuzzy controller has been investigated. The proposed control consists of an ordinary fuzzy controller and a fuzzy supervisor. In a machining process, there are several parameters which do not contribute to the force control system directly. Therefore an ordinary fuzzy force controller is suitable when these parameter have only small amount of variations. Since in practice this assumption is not valid, then a supervisory fuzzy controller has been added to the system. The designed fuzzy supervisor, inspects the dynamic behavior of the cutting force, estimates a pre-defined ‘sensitivity’ parameter and... 

In recent years, the seat suspension system in commercial vehicles, industry, agriculture, transportation and … have been focused by researchers. Designing the spring-damper isolators for vehicle’s seat can be an achievable and suitable strategy to increase the comfort and decrease the risk of injuries in vehicles. In this research, the effect of vibrations due to road roughness has been examined by dynamic modeling of a vehicle in combination with the human body model. Thus by using spring-damper isolators and genetic algorithm, we try to optimize the performance of the system. Designing parameters includes the stiffness and viscosity of seat isolator and our target functions include the... 

In this thesis, coordination of a group of autonomous agents, through a scalable control structure and with very limited communications, is addressed. Inter-agent action functions are designed to guarantee the network connectivity. Two coordinator agents with different natures are designed. One is attractive and is named leader-agent (LA). The other is repulsive and is named shepherd-agent (SA). Under the assumption that both coordinators locally affect the group, we have proved that the governing equation of the whole group may have variable order.
By using nonlinear control techniques, coordination algorithms are designed to move the group on a predefined path or to a destination. It... 

Nowadays, many researches are inspired by nature and living creatures in order to build various scientific and industrial products such as robots, because of the highest level of creativity which is used in creating them along with their high level of efficiency in power consumption and designing parameters. Underactuated Robots are the type of robots which have more degrees of freedom comparing to the number of operators. As a result their optimum control has a lot of complications. Brachiating robots are designed and built based on an inspiration from long armed apes (Gibbons). This type of monkey is highly skilled in twisting in trees and traversing. This type of movement benefits from... 

Smart structures are the combination of structure, smart material, electronics and control technologies. Changing the shape of the structures by smart actuators is one of the most important applications of Shape Memory Alloy (SMA) in these structures. Having used these actuators, we can effortlessly and continuously deform and reshape the structures. Nevertheless, working with SMA actuated smart structures has one obvious drawback that is their hysteretic and nonlinear behavior, making modeling and control of these structures complex. Another difficulty in the control of smart structures is their great sensitivity to the actuating force that reduces the controllability of these structures.... 

An essential requirement for performing robotic assisted surgery on a freely beating heart is a prediction algorithm which can estimate the future heart trajectory with a high accuracy in a long horizon. The main objective of this research was measurement and prediction of the heart motion for robotic assisted beating heart surgery. In this study, first the feasibility of a stereo infrared tracking system for measuring the free beating heart motion was investigated by experiments on a heart motion simulator. Simulator experiments revealed a high tracking accuracy when the capturing times were synchronized and the tracker pointed at the target from an appropriate distance.Then, the heart... 

Oil and natural gas today are one of the most important sources of human energy supply, so that crude oil Percentage and natural gas provide 25% of the world's energy. Until now, vertical drilling methods have been used to extract oil and gas. In recent years, due to vertical drilling constraints, for extraction and access to places that can not be achieved by vertical drilling, Horizontal drilling has been increased. In horizontal drilling, a variety of vibrations including longitudinal, torsional, and lateral take place. These vibrations, if not controlled, can damage the equipment and the drilling field, as well as reduce the efficiency of the drilling process and increase the process... 

Endoscopic sinus surgery is a minimally invasive surgery. Today, for the education of such surgeries, the surgical simulators are used. They could be used for both training of such a technique and pre operation planning. One of the features that could improve the efficiency of these systems and prepare the effective interaction with them is haptic.
In this thesis, an inexpensive sinus surgery simulator has been designed and implemented such that the operator could see sinus nasal in real time and could detect collisions between tool and virtual environment.
In this research, a 3D surface rendered model that extracted from 2D CT images has been used for construction of virtual...