Erfan Shojaei Barjuei

Bio: Erfan Shojaei Barjuei is an academic researcher from Istituto Italiano di Tecnologia. The author has contributed to research in topics: Linear-quadratic regulator & Torque sensor. The author has an hindex of 5, co-authored 12 publications receiving 109 citations. Previous affiliations of Erfan Shojaei Barjuei include Sant'Anna School of Advanced Studies & University of Udine.

Localization strategies for robotic endoscopic capsules: a review.

Abstract: Introduction: Nowadays, mass screening campaigns for colorectal cancer diagnosis in the early and curable stage is essential yet limited due to many reasons, for example, invasiveness, fear of pain...

Optimal Selection of Motors and Transmissions in Back-Support Exoskeleton Applications

Abstract: Because of the central role the actuator unit (electrical motors and transmission parts) has in wearable robots, improving the performance of the torque/force control system is vital, particularly for exoskeletons. This paper proposes an optimal approach to the selection of the main components of an actuation system (brushless DC motor and gearbox transmission) to be used in a back-support exoskeleton, but the principles can be extended and applied to other types of exoskeletons. To perform the optimization, an analytical model based on the dynamics of human–robot interaction has been developed. Moreover, to incorporate the weight of the actuator in the optimization framework, a mathematical relation between the weight and technical characteristics of the components, based on the polynomial regression technique using the low-discrepancy sequences method are developed. Consequently, the optimization criteria in terms of the closed-loop system frequency bandwidth, system power consumption and the weight of the components are formulated by imposing technical constraints on simulation parameters. The optimization results demonstrate two possible actuator combinations. Subsequently, the selected actuator components are evaluated in a lifting scenario by means of a linear quadratic regulator (LQR) controller with double integral action. Extensive simulation results in terms of the control frequency bandwidth, torque tracking control, current produced by motors and system robustness with respect to external disturbances are presented and discussed to make comparisons between the possible combinations of the components and their feasibility in the back-support exoskeleton applications.

Linear quadratic optimal controller for cable-driven parallel robots

Abstract: In recent years, various cable-driven parallel robots have been investigated for their advantages, such as low structural weight, high acceleration, and large work-space, over serial and conventional parallel systems. However, the use of cables lowers the stiffness of these robots, which in turn may decrease motion accuracy. A linear quadratic (LQ) optimal controller can provide all the states of a system for the feedback, such as position and velocity. Thus, the application of such an optimal controller in cable-driven parallel robots can result in more efficient and accurate motion compared to the performance of classical controllers such as the proportional- integral-derivative controller. This paper presents an approach to apply the LQ optimal controller on cable-driven parallel robots. To employ the optimal control theory, the static and dynamic modeling of a 3-DOF planar cable-driven parallel robot (Feriba-3) is developed. The synthesis of the LQ optimal control is described, and the significant experimental results are presented and discussed.

The Global Positioning System

Abstract: This research study explores the Global Positioning System (GPS), its history, and the process of discovery needed to create the most accurate GPS possible, as well as the contemporary applications of GPS technology. Starting with the first satellite in space, GPS has been a work in progress. Originally pursued by the military for improvements to military tactics, GPS has become integrated into the everyday lives of millions of people around the world. How GPS determines location is a dichotomy, with simplistic theory and complex application. Many factors go into GPS to provide a consistent, accurate location. The orbital planes the satellites are placed in provide 24/7 coverage globally, the L-band frequencies used were chosen specifically for the characteristics they possess, and the multiple atomic clocks installed on each satellite provide incredible accuracy down to the nanoseconds, which is quintessential in GPS accuracy. The applications in GPS are far reaching and more applications are continually being discovered. With as far as GPS technology has progressed, there are still several factors that degrade the signal and are a challenge to overcome. Many of these challenges can be corrected efficiently, however, others, such as scintillation and total electron content variability in the ionosphere, create major hurdles to overcome. Luckily, there are many programs that aid in the correction process of these hurdles. The History of GPS According to R. Saunders’ article ​A Short History of GPS Development,​ The Global Positioning System (GPS) has a long history of trial and error and refinement and improvement. It’s purpose has shifted from being a military strategic asset to commonplace among the general public with its use in traveling, farming, and even banking. The beginning of GPS, introduced with a simple idea, can be traced back to the Soviet Union in the late 1950’s. In 1957, the Soviet Union made history with successfully launching the first satellite in space. To track the satellite Sputnik, Physicists and Scientists at John Hopkins University’s Applied Physics Laboratory listened to the beeps Sputnik’s signals produced. They noticed that the beeps had a Doppler Effect or Doppler Shift as the satellite passed by. Much like the sound a siren makes as a fire truck approaches, then as it passes, the sound of the siren seems different. The change in timing between the beeps let the scientist know Sputnik’s location. This led to the idea of reversing that process, to give a location on the Earth. Using radio frequencies to determine location in a two dimensional plane had been around since WWII, but using satellites would push this technology into the three dimensional realm. The United States Navy, Army, and Air Force all began developing their own GPS satellites in the 1960’s, but this was no small task. In the early 1960’s, the Navy launched its first Transit Satellite. The failure of this satellite, however, was due to

Force Sensing Resistor and Evaluation of Technology for Wearable Body Pressure Sensing

Abstract: Wearable technologies are gaining momentum and widespread diffusion. Thanks to devices such as activity trackers, in form of bracelets, watches, or anklets, the end-users are becoming more and more aware of their daily activity routine, posture, and training and can modify their motor-behavior. Activity trackers are prevalently based on inertial sensors such as accelerometers and gyroscopes. Loads we bear with us and the interface pressure they put on our body also affect posture. A contact interface pressure sensing wearable would be beneficial to complement inertial activity trackers. What is precluding force sensing resistors (FSR) to be the next best seller wearable? In this paper, we provide elements to answer this question. We build an FSR based on resistive material (Velostat) and printed conductive ink electrodes on polyethylene terephthalate (PET) substrate; we test its response to pressure in the range 0–2.7 kPa. We present a state-of-the-art review, filtered by the need to identify technologies adequate for wearables. We conclude that the repeatability is the major issue yet unsolved.