A Modified Control Approach to Increase Singularity Avoidance in 7-DOF Redundant Arms

A Modified Control Approach to Increase Singularity Avoidance in 7-DOF Redundant Arms

… Download …


Part of #A Modified Control Approach to Increase Singularity Avoidance in 7-DOF Redundant Arms# :

Publishing year : 2013

Conference : 16th Iranian Student Conference on Electrical Engineering

Number of pages : 5

Abstract-This paper deals with the singularity of avoidance in the process of position and force control of a 7-DOF redundant robot arm using a signal in combination with a control signal. In this paper, singularity avoidance is considered as an secondary task and an external-internal loop controller called the augmented hybrid impedance control scheme is used. The inner loop consists of a Cartesian-level potential difference controller, a redundancy resolution scheme at acceleration level, and a joint-space inverse dynamics controller. Simulation results for a 7-DOF robot arm are given to illustrate the performance of the proposed technique. The proposed algorithm affects the control signal for a redundant robot so as to increase its singularity of avoidance and the results showed a significant increase in robot runtime. A strategy for adapting the parameters for a different kind of robot was developed and specially implemented for a PA10 7-DOF redundant robot. The proposed scheme is applied to the Mitsubishi PA10 7-DOF robot arm and the results showed that the motion profile of the robot became smoother and their runtime increased.

Behaviour of High-Strength Concrete Squat Shear Walls Subjected to Reversed Cyclic Loading – An Experimental Study

Behaviour of High-Strength Concrete Squat Shear Walls Subjected to Reversed Cyclic Loading – An Experimental Study

… Download …


Part of #Behaviour of High-Strength Concrete Squat Shear Walls Subjected to Reversed Cyclic Loading – An Experimental Study# :

Publishing year : 2009

Conference : Eighth International Congress of Civil Engineering

Number of pages : 8

Abstract: Six high-strength concrete squat shear walls were tested under in-plane axial load and reversed cyclic displacements. The test parameters include a longitudinal reinforcement ratio, a transverse reinforcement ratio, and axial load. Lateral loads and lateral displacements were measured. The test results showed that the axially loaded wall specimens exhibited a brittle behavior regardless of the reinforcement ratio, whereas the specimen without axial load had a lower strength, but a higher elasticity. It was also found that an increase in longitudinal reinforcement ratio increased the failure load, while the increase in cross-reinforcement ratio did not have a significant effect on the strength, but affected the failure mode.

Attitude Control of MAVs using L1 Adaptive Algorithm

Attitude Control of MAVs using L1 Adaptive Algorithm

… Download …


Part of #Attitude Control of MAVs using L1 Adaptive Algorithm# :

Publishing year : 2011

Conference : 19th Annual Conference of Mechanical Engineering

Number of pages : 4

Abstract: PID controllers offer high performance for Micro Air Vehicles (MAVs), but they have to be tuned for each MAV and even for each flight test. Moreover, MAV dynamics changes by time and consequently, PID controller performance decreases. Thus, an adaptive control system that compensates for these changes is developed in this research. On the other hand, the size of the autopilot system is a major factor. Many adaptive control algorithms suffer from time consuming computing and need for high memory. In this paper, an L1 adaptive controller is developed that self-tunes to each MAV and compensates for changes in the MAV during its flight. The proposed controller is both simple and efficient. This autopilot system controls the pitch angle through the elevator commands. The simulation results show the efficiency of the proposed control system.

Art Movements and Interaction in Interior Architecture with the Approach of Contemporary Architecture

Art Movements and Interaction in Interior Architecture with the Approach of Contemporary Architecture

… Download …


Part of #Art Movements and Interaction in Interior Architecture with the Approach of Contemporary Architecture# :

Publishing year : 2014

Conference : Second National Conference on Applied Research in Civil Engineering, Architecture and Urban Management

Number of pages : 6

Abstract: Art in the twentieth century has been innovated and evolved more than previous centuries. So in the contemporary art, the artist's individual influence has surpassed the influence of the artist's work, and the artist's focus is attention, whereas in the old art, the artist's work was influential and also the artist's works were Formed based on peoples flavors. But today, by focusing on the artist, people's tastes have been pushed aside and the artist's feelings have emerged. Absence of art work in interior building creates contradiction with the person who favors art. The created space should have artistic features or could place art works in the best of manifestation in order to be able to interact with the person's cognitive ability. This point can also be insisted that the nature inventory of interior space is designed for human and without interior space; The building looks like a great statue. Art movements generated in recent decades have caused that new needs to be felt whether for displaying works in a particular environment or integrating space and art work; In a wider environment, the created interior space can be viewed as an art work in prevailing art movements.

Routing in Ad Hoc Networks with Limited Forwarding Capability

Routing in Ad Hoc Networks with Limited Forwarding Capability

… Download …


Part of #Routing in Ad Hoc Networks with Limited Forwarding Capability# :

Publishing year : 2006

Conference : Fourteenth Iranian Conference on Electrical Engineering

Number of pages : 6

Abstract: In some ad hoc networks, each MS can participate in at most one connection. When ad hoc networking is used to extend the coverage area of an infrastructure-based wireless system, we are faced with this condition. When mobile stations have a limited forwarding capability, a number of routes may be blocked. In this paper, new routing strategies are proposed in order to improve the performance of ad hoc networks constructed out of MS with a limited forwarding capability. Also, properties of the routes that are found using different metrics are studied through simulations.

Applications of Vygotsky”s Sociocultural Approach for Teachers”Professional Development

Applications of Vygotsky"s Sociocultural Approach for Teachers"Professional Development

… Download …


Part of #Applications of Vygotsky”s Sociocultural Approach for Teachers”Professional Development# :

Publishing year : 2015

Conference : Second International Conference on Behavioral Sciences and Social Studies

Number of pages : 12

Abstract: This paper outlines an approach to teachers 'professional development that originates in Vygotsky's (1978, 1981) sociocultural theory (SCT), arguing that what Vygotsky claimed about students' learning in the school setting is applicable to teachers and that the developmentalheories (Vygotsky, 1998) can help more vividly understand the professional growth of teachers in their work places. The paper discusses how seven influential models of professionaldevelopment mainly (Guskey, 2000; Kozulin, 2003; DuFour, 2005) canbe best grounded in Vygotsky's theoretical work, which is based on the theory and practice of research, Framework. It is claimed that the commonality that interweaves the aforementioned models is the "Vygotsky" concept of "social mediation" (Vygotsky, 1987). Finally, the paper concludes with discussion of different implications of the proposed approach for designing and implementing teacher's professional development, linking developmental aspects Of professionaldevelopment and core tenets of Vygotsky's developmental theories.

Foraminiferal Description of Eocene Deposits in South-West of Iran

Foraminiferal Description of Eocene Deposits in South-West of Iran

… Download …


Part of #Foraminiferal Description of Eocene Deposits in South-West of Iran# :

Publishing year : 2015

Conference : International Conference on Engineering, Science and Technology

Number of pages : 9

Abstract: Eocene deposits in the Zagros basin in the tow zones of the interior of Fars and Izeh include limestone and marly limestone succession along with abundant fossils. The significance of this area is due to its hydro carbonic resources. In Dashte Kuh section, limestone and marly limestone deposits with medium to thick creamy layers containing benthic foraminifera could be seen. Bio-zones identified in such deposits include Opertorbitolites Subzone, Somalina Subzone, Alveolina Nummulites Assemblage Subzone, and Nummulites Fabianii Silvestriella tetraedra Assembelage Zone. In the Nil Kuh section, the marly limestone of the succession contains abundant plagic foraminifera. The zones identified in this succession include Morozovella aragonesis Range Zone, Hantcanina nuttalli Range Zone, Hantcanina nuttalli Turborotalia cerro-azulensis Interval Zone, Turborotalia cerro-azulensis Range Zone and Morozovella aragonesis Range Zone

Sustainable Security In The Persian Gulf: Challenges And Barriers

Sustainable Security In The Persian Gulf: Challenges And Barriers

… Download …


Part of #Sustainable Security In The Persian Gulf: Challenges And Barriers# :

Publishing year : 2015

Conference : International Conference on Management Economics and Social Sciences

Number of pages : 6

Abstract: The geopolitical district of the Persian Gulf is considered as one of the most important regions of the world from the point of view of geostrategicand geo-economic issues. Therefore, the security of the Persian Gulf is of great significance both at regional and global levels. Since 1980, thePersian Gulf has witnessed three major wars, and their consequences have made it necessary to establish a lasting and effective security inthis geopolitical district. The main purpose of this article is to study the challenges to the realization of such a stable security in the geopolitical district of the Persian Gulf and, ultimately, to achieve a comprehensive stability and security in that region. Meanwhile, according to the essence of the subject, the descriptive-analytical method is applied to present research. The results showed that: In the regional level, border disputes and territory claims, religious disagreements and thegeopolitical antagonism of the regions' countries; And in the transregional level, the presence of the USA as a trans-regional interventionist actor who has been in existence in this geopolitical district since 1970 has made some obstacles and challenges to the stable security of the Persian Gulf geopolitical district.

SEISMIC RESPONSE OF BASE-ISOLATED STRUCTURES USING DCFP BEARINGS WITH TRI-LINEAR AND BI-LINEAR BEHAVIORS

SEISMIC RESPONSE OF BASE-ISOLATED STRUCTURES USING DCFP BEARINGS WITH TRI-LINEAR AND BI-LINEAR BEHAVIORS

… Download …


Part of #SEISMIC RESPONSE OF BASE-ISOLATED STRUCTURES USING DCFP BEARINGS WITH TRI-LINEAR AND BI-LINEAR BEHAVIORS# :

Publishing year : 2011

Conference : 6th International Conference on Seismology and Earthquake Engineering

Number of pages : 8

Abstract: A double concave friction pendulum (DCFP) system is a newly developed kind of friction pendulum system that consists of two sliding surfaces. In the current paper, we investigate the three-dimensional base-isolated structures of seismic responses using DCFP systems considering tri-linear and bi-linear behavior. After deriving the coupled differential equation of motion, a computer program has been developed to obtain time-response response of base-isolated structures under earthquake excitations. The advantages and disadvantages of a trilinear behavior over a bi-linear one are studied by studying the effect of the main parameters such as the isolation period, the ground motion amplitude and the friction coefficient of the surfaces on peak responses under seven earthquakes. It is shown that tri-linear DCFP bearings, in comparison with bi-linear bearings, can reduce the base shear up to about 48 percent. However, tri-linear DCFP bearings cause larger displacements of sliding surfaces than bi-linear ones that reach 57%.

Integrated Modeling of Global and Regional Model in Investigation of Tidal Current in Port of Bushehr Iran

Integrated Modeling of Global and Regional Model in Investigation of Tidal Current in Port of Bushehr Iran

… Download …


Part of #Integrated Modeling of Global and Regional Model in Investigation of Tidal Current in Port of Bushehr Iran# :

Publishing year : 2013

Conference : International Conference on Civil Engineering, Architecture and Sustainable Urban Development

Number of pages : 11

Abstract: The present study modeled the coastal patterns in Bushehr Port using a two-dimensional model, and compared the results with measured data to analyzes the tidalcurrents. In this regard, the hydrodynamic conditions of the Bushehr Port, including current velocity, current direction, and sea-level changes, were examined using the HD module inMIKE 21 software. For numerical modeling, a non-uniform triangular lattice was studied using two meshing schemes: a coarse general network and a fine regional network. The length of each element is variable between 310 and 2400 m in 6 regions. After calibratingthe model, the data of a one year period, 2011, were analyzed. The currrents' boundary conditions were applied in the regional modeling domain (Bushehr Port) with three openboundaries and the general modelling domain (Persian Gulf) with one open border in the Strait of Hormuz and. Regarding this, four main tidal factors of 2 2 1 1 M, S, K, O were considered to predict tidalbehavior in the open boundary. Finally, there was no significant difference between the measured data and the modeling results and the rarely observed errors could be attributed to the insufficient data for input input conditions.