Sharif University of Technology
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- Offer Profile
Welcome to the Center of Excellence in Design, Robotics,
and Automation (CEDRA).
CEDRA is the premier applied research, education and technology center in
The main goal of this group is to develop the relationship between university
and industry and it tries to fill the existent gap between them. Therefore the
main activity of this team has been focused on researches about designing and
manufacturing of industrial grade rescue robots.
Minimum Control Effort
Trajectory Planning and Tracking Control for Brachiation Robot
- Seyyed Mohammad Hosseini Lavasani, Mohsen Norouzi
and Ali Meghdari
Abstract–The Brachiation robot is a kind of mobile robot that imitates the
movement of a long-armed ape swinging from branch to branch. Unlike other
robots where the gravity force is one of the difficulties which reduce the
stability of the system, it helps this robot to use minimum control effort
to move from a branch to another. Here, the brachiation robot is considered
as a two degree of freedom underactuated system. The control of
underactuated mechanical systems is a research topic that has been studied
extensively during the past years.
Here, as a new innovation, Pontryagin's minimum principle is used to obtain
the optimal trajectories for two different problems. The first problem is
“Brachiation between fixed branches with different distance and height” and
the second is “Brachiating and catching the moving target branch”.
Theoretical results show that the control effort in the proposed method is
reduced by 25% in comparison with the “Target Dynamics” method which was
proposed in prior articles for this robot. Two kinds of controllers, the PD
and the Adaptive Robust, are investigated for tracking the proposed
trajectories. These controllers have the capability to be used in systems
which have uncertainty in the inertial parameters. Lastly, experimental
results are included to validate the proposed controller for the CEDRA
CEDRA brachiation robot.
The continuous movement of CEDRA brachiation robot
between symmetric intervals.
The movement of CEDRA brachiation robot on Ladder with
Swarm Robotic: an
- Alireza Nemati, Mehdi Farshchi, Ali Meghdari
In this study, an adaptive control scheme for multi-agent formation control
is proposed. This control method is based on artificial potential functions
integrated with adaptive fuzzy sliding mode control technique. We consider
fully actuated mobile agents with completely unknown dynamics. An adaptive
fuzzy logic system is used to approximate the unknown system dynamics.
Sliding Mode Control (SMC) theory is used to force agents’ motion to obey
the dynamics defined by the simple inter-agent artificial potential
functions. Stability proof is given using Lyapunov functions, which shows
the robustness of controller with respect to disturbances and system
uncertainties. Simulation results are demonstrated for a multi-agent
formation problem, illustrating the effectiveness of the proposed method.
Experimental results are included to verify the applicability of the scheme
for a test-bed of six real mobile robots.
Swarm of autonomous robots acting together
Simulations of Surface Defects Characterization Using
Force Modulation Atomic Force Microscopy
- Hossein Nejat Pishkenari and Ali Meghdari
Using FFM-AFM, characterization of sample defects by a recently developed
gold coated AFM probe in air is investigated. In this research, an online
imaging simulation of the probe and surface is performed, and the effects of
the horizontal scan speed, and effective frequency set-point on the
resulting images are illustrated. The excitation force amplitude adjustment
based on the value of the effective oscillation frequency was made through a
PID controller. The research results are beneficial in providing data on the
mechanisms of sample damage and also on the relative stiffness of the
different surface regions.
View of the model used in the construction of the
tip-sample interaction force
The topography difference of the simulated Ag sample
(with vacancy, Cu and Pb atoms) and a pure Ag sample
The effect of scan speed on the topography
The effect of set-point frequency on the topography
A Dynamic Object Manipulation Approach to Dynamic Biped
- Borhan Beigzadeh, Ali Meghdari (Advisor) and
Majid Nili Ahmadabadi (Co-advisor, University of
In this study, we aim at an integrated approach
to Dynamic Biped Walking (DBW) and Dynamic Object Manipulation (DOM) at an
abstract level. To this end, we offer a unified and abstract concept with a
dual interpretation as a DOM and as a DBW system. We validate the proposed
approach by using a set of simulations on an illustrative case study and
show how it can be used in modeling as well as design of planning and
control algorithms for DOM and DBW systems.
In the case study, we describe the proposed
approach and show its dual interpretation by identifying the relations
between 2D dynamic object manipulation of a disc using two planar
manipulators and 2D dynamic object locomotion of lower part of a biped
robot. More specifically, having obtained the equations of DOM, we change
the boundary conditions of the problem in such a way that both radius and
mass of the disc tend to infinity. Simultaneously, both size and mass of the
manipulators' base, i.e. the planet earth, tend to some values in the order
of human's body mass and dimension. Regarding these changes, we can
transform DOM into DBW and vice versa.
To test the proposed approach, a simple control
strategy is introduced to handle impact between the manipulators (legs) and
the object (the earth). In addition, a motion planning system is designed in
such a way that the manipulators (legs) catch and throw the manipulated
object (the earth) in appropriate configurations.
In the simulations, we first simulate the manipulation of a disc both in the
presence of disturbance and without any disturbance. Having obtained
acceptable results, we then simulate the dynamic walking process. The biped
robot is dropped on the ground from the height of 1.25 meter with the
initial horizontal velocity of 2 meter per second. The robot finally reaches
a semi-steady state of running. It can be observed that the robot's running
style is not perfect which was expected as we have put no effort in
optimization of the trajectory and the control parameters in this phase of
our research. Also the robot cannot tolerate big disturbances ([-350N,
350N]) and falls. See figures below.
Manipulation and locomotion from an absolute point of view
Planar motion of the disc center | system without
FIG.7: Planar motion of the disc center | system with
Snapshots from one cycle of biped running | system
Some Snapshots of the robot falling because of large
CEDRA Rescue Robot
- Ali Meghdari, Hanif Mahboobi, Hossein Nejat Pishkenari, Saeid Bagheri, Amir Lotfi, Reza Karimi, Yaser Khalighi, Ali Baghani, Farshid Amiri
Intelligent mobile robots and cooperative multi-agent robotic systems can be
very efficient tools to speed up search and rescue operations. Rescue robots
are also useful to do rescuing jobs in situations that are hazardous for
human rescuers. They can enter gaps and move trough small holes that are
impossible for humans and even trained dogs. Robots should explore in
collapsed structure, extract the map, search for victims and report the
location of victims in map and the way that rescue team can reach him/her.
It can also place a small package containing food, drugs and a communication
device near the victim.
So the rescue robots for reaching to the above goals should have the
following features and capabilities:
- autonomously navigate through collapsed structures
- find victims and ascertain their condition
- produce practical maps of their locations
- deliver real-time communications
- identify hazards
The CEDRA rescue robot has shown it's capabilities in international
arenas. It achieved second place in international Robocop competition (in
real rescue league) which was held in Padua, Italy. All team members are top
and elite students from different departments of Sharif University of
Technology (Mechanical, Electrical and Computer Engineering).
CEDRA Rescue Robot
CEDRA Rescue Robot
CEDRA Rescue Robot
CEDRA Rescue Robot
Molecular Dynamics Assisted Simulation of Nanoscale
Effects in Nanomanipulation
- Hanif Mahboobi and Ali Meghdari
Nanomanipulation as a new emerging area enables one to precisely change,
interact and control the nano-scale phenomena. A main consideration of
nanomanipulation is that surface attraction forces are greater than
gravitational forces at nanoscale. In other words, surface area properties
dominate over volume properties. Currently, the modeling schemes are based
on continuum mechanics approaches. Especially at the nano-scale (i.e.
manipulation of fine nanoparticles with size of about 5nm) the physical and
chemical phenomena have not been completely understood. Thus, the aim of
this research is to conduct an atomistic investigation of physical
interaction analysis of the manipulation tool (e.g. STM tip), and nano-scale
objects for manipulation and positioning tasks. To perform this research
Nose-Hoover dynamics and Sutton-Chen interatomic potential will be used to
investigate the behavior of tip-particle-substrate system which is made from
different transient metals.
Expected Results and General Achievements:
- Atomistic simulation of nanoscale interactions in
tip-particle-substrate system as a framework for MD modeling of
- Better understanding of stick-slip, sliding and rolling behavior of
the tip-particle-substrate system and their emergence condition
- Better understanding of adhesion phenomenon in the
tip-particle-substrate system and its feasibility as a nanomanipulation
process (including the release approach)
- Determining the tip and substrate materials' type effects on the
success of manipulation process
- Better understanding of the effects of surface roughness, vacancies
and lubricants on nanomanipulation.
- Improvements of nanomanipulation algorithms for ultra fine
Simulation of Nanoscale Effects in Nanomanipulation