Iosif S Paraskevas | National Technical University of Athens (original) (raw)

Journal Papers & Book Chapters by Iosif S Paraskevas

The paper summarizes the participation of the 6 FabSpaces to the population estimation (remote) p... more The paper summarizes the participation of the 6 FabSpaces to the population estimation (remote) pilot task at ImageCLEF 2017 Lab. FabSpace 2.0 is an open-innovation network for geodata-driven in- novation that aims at improving universities contribution to the socio- economic and environmental performance of societies. In the framework of the ImageCLEF Lab, the 6 FabSpaces participated although only four of them succeeded in submitting a run. This paper summarizes their par- ticipations. For each FabSpace, we present the local organization to par- ticipate to the CLEF Lab, the participants and their work. We conclude this paper with some lessons we learned from this participation.

—The goal of FabSpace 2.0 project is to transform Universities to Open Innovation Centers for the... more —The goal of FabSpace 2.0 project is to transform Universities to Open Innovation Centers for their corresponding region and improve their societal contribution to the socioeconomic and environmental performance. For this purpose, the project provides to students, researchers, as well as to citizens or even companies, with a framework and a digital platform which gives open access to a range of geodata, i.e. Earth Observation data, but also computing and visualization tools. By this way, it is expected that the participants can work in an open co-working space, where they can interact with each other. Additionally, the participants will be assisted to assess the business aspects of any potential idea. The outcome of such an activity is the increase of possibility for participants to find a revolutionary concept, which can result to new and sustainable applications and/or services. Moreover the target group exceeds the usual Earth Observation professionals, and focuses also in professionals of other disciplines, where the use of Earth Observation data can create novel technologies.

In this paper, the development of an Orbital Robotics educational prototype platform is presented... more In this paper, the development of an Orbital Robotics educational prototype platform is presented, consisting of a hardware-developed physical system and an accompanying set of curriculum-based lessons (IB Physics curriculum) that target upper secondary students (16-18 years old target group). The students interactively use the hardware , consisting of a bespoke space-emulating table and small satellite mockups. During the lessons, this platform allows students to acquire knowledge of the dynamics of space systems, as well as the environmental conditions and physical constraints that characterize on-orbit operations. Students will be able to manipulate the space robot (satellite) mockups performing basic tasks such as docking, and landing or grasping space debris. Additionally, a smartphone application has been implemented to allow the interaction with the platform, via a dedicated User Interface (UI). The lessons are inquiry-based and are structured so that the students are actively engaged in the learning process, according to a learner-centric approach.

Development and prototyping of robotic systems requires the involvement of many people and many h... more Development and prototyping of robotic systems requires the involvement of many people and many hours of design, development and cooperation; significant time and effort overhead is required for evaluating conceptual ideas in design, control and technology, and for bringing them fast into reality for testing. Based on the important advances of the last decade in hardware and software, a simple and low cost framework and its underlying ideas are presented, with steps that aim at accelerating robotics research work in academia and industry. The framework’s functionality is validated and illustrated by two application examples concerning the control systems of a single- legged hopping robot and an instrumented treadmill. The software required to conduct the same experiments is provided, with the intention to help the reader reuse it in similar applications.

In this paper, the development of an Orbital Robotics educational prototype platform is presented... more In this paper, the development of an Orbital Robotics educational prototype platform is presented, consisting of a hardware-developed physical system and an accompanying set of curriculum-based lessons (IB Physics curriculum) that target upper secondary students (16–18 years old target group). The platform was the outcome of a joint project between the European Space Agency and the National Technical University of Athens. The students use the hardware interactively, consisting of a bespoke space-emulating table and small satellite mockups. The lessons are inquiry-based and are structured so that the students are actively engaged in the learning process, according to a learner-centric approach. During the lessons, this platform allows students to acquire knowledge of the dynamics of space systems, as well as of the environmental conditions and physical constraints that characterize on-orbit operations. Students are able to manipulate the space robot (satellite) mockups performing basic tasks such as docking and landing, or grasping space debris. Additionally, a smartphone application has been implemented to allow the interaction with the platform, via a dedicated User Interface (UI).

Highlights Consideration of the effects of permanent ground deformation and compaction. Developme... more Highlights Consideration of the effects of permanent ground deformation and compaction. Development of a controller immune to terrain compliance. No knowledge requirement of ground parameters. Successful tackle of foot slip effects and hard impacts during touchdown. The methodology can be extended to other legged robots such as quadrupeds. Abstract One of the most intriguing research challenges in legged locomotion is robot performance on compliant terrains. The foot-terrain interaction is usually tackled by disregarding some of the effects of ground deformation, like permanent deformation and compaction; however this approach restricts their application to stiff environments. In this work, the foot-terrain interaction is studied, and used in developing a controller immune to terrain compliance. An impact dynamics model is developed, employing a viscoplastic extension a b b

Exploitation of space must benefit from the latest advances in robotics. On-orbit servicing is a ... more Exploitation of space must benefit from the latest advances in robotics. On-orbit servicing is a clear candidate for the application of autonomous rendezvous and docking mechanisms. However, during the last three decades most of the trials took place combining extravehicular activities (EVAs) with telemanipulated robotic arms. The European Space Agency (ESA) considers that grasping and refuelling are promising near-mid-term capabilities that could be performed by servicing spacecraft. Minimal add-ons on spacecraft to enhance their serviceability may protect them for a changing future in which satellite servicing may become mainstream. ESA aims to conceive and promote standard refuelling provisions that can be installed in present and future European commercial geostationary orbit (GEO) satellite platforms and scientific spacecraft. For this purpose ESA has started the ASSIST activity addressing the analysis, design and validation of internal provisions (such as modifications to fuel, gas, electrical and data architecture to allow servicing) and external provisions (such as integrated berthing fixtures with peripheral electrical, gas, liquid connectors, leak check systems and corresponding optical and radio markers for cooperative rendezvous and docking). This refuelling approach is being agreed with European industry (OHB, Thales Alenia Space) and expected to be consolidated with European commercial operators as a first step to become an international standard; this approach is also being considered for on-orbit servicing spacecraft, such as the SpaceTug, by Airbus DS. This paper describes in detail the operational means, structure, geometry and accommodation of the system. Internal and external provisions will be designed with the minimum possible impact on the current architecture of GEO satellites without introducing additional risks in the development and commissioning of the satellite. End-effector and berthing fixtures are being designed in the range of few kilos and linear dimensions around 15 cm. A central mechanical part is expected to perform first a soft docking followed by a motorized retraction ending during a hard docking phase using aligning pins. Mating and de-mating will be exhaustively analysed to ensure robustness of operations. Leakage-free valves would allow for the transfer of fuel to the serviced spacecraft. The validation of the ASSIST system through dedicated environmental tests in a vacuum chamber together with dynamic testing using an air-bearing table will allow for the demonstration of concept feasibility and its suitability for becoming a standard of the on-orbit space industry.

During capture of a free-flying object, a robotic servicer can be subject to impacts, which may s... more During capture of a free-flying object, a robotic servicer can be subject to impacts, which may separate it from the object or damage crucial subsystems. However, the reactions can be minimized using the Centre of Percussion (CoP) concept. Following a brief introduction of the two- and three-dimensional cases, the performance of a robot under impact is assessed when the cop concept is employed. The effects of the parametric uncertainties on manipulator joint reactions are studied. Α control method to compensate for the reaction forces is proposed. Implementation guidelines are discussed. Simulations of a planar space robot validate the analysis.

NanoRobotics: Current Approaches and Techniques

Space is an exciting but fundamentally unfriendly environment for mankind. Space robotic systems ... more Space is an exciting but fundamentally unfriendly environment for mankind. Space robotic systems (robots in orbit, planetary rovers or even satellites) are of great importance to space exploration and perform hazardous or impossible for humans tasks. Using micro/nano technologies in space robotic systems results ei- ther in miniaturized systems in terms of volume and mass, while retaining or in- creasing their capabilities, or in space robots with increased capabilities while re- taining their size due to the nature of their tasks. Examples of miniaturization possibilities for space robots and satellites are given, focusing on the challenges and the enabling technologies. The miniaturization process and the use of ad- vanced micro/technologies in space will have a large beneficial impact in the years to come.

Refereed International Conference Proceedings by Iosif S Paraskevas

24th Mediterranean Conference on Control and Automation (MED), Athens, Greece, 2016

On-orbit servicing missions will rely on space robots; however their complexity requires prior ca... more On-orbit servicing missions will rely on space robots; however their complexity requires prior careful studies. Among these, robotic docking is especially challenging. In this work, the robotic impact docking between two space systems is considered. The impedance properties required to design an impedance controller are studied. These properties include the ratio of the masses between the systems under impact, the relative stiffness between the bodies of each space system and the associated damping factor. The velocity of the probe tip to be commanded is calculated aiming at successful latch at first impact. Simulation results validate the proposed approach.

6th International Conference on Robotics in Education (RiE ’15)

As part of its Education Programme, the European Space Agency (ESA) is taking several steps towar... more As part of its Education Programme, the European Space Agency (ESA) is taking several steps towards the devel- opment of Educational activities and platforms that use Space Robotics as a mean to support and reinforce STEM (Science, Technology, Engineering and Mathematics) school education in Europe. In this paper the on-going development of an Orbital Robotics educational prototype platform is presented, consisting of a hardware-developed physical platform and an accompanying set of curriculum-based lessons (IB Physics curriculum) that target upper secondary students (16-18 y/o target group). The hardware, a friction-less air-hockey table (physical platform) engineered for this purpose, will be used by students to interac- tively acquire the necessary experience of the dynamics of space systems, as the environmental conditions and physical constraints that are characteristic of on-orbit systems are emulated. The stu- dents will be able to manipulate space robot (satellite) mockups performing basic tasks such as docking, landing and grasping space debris. Additionally, a smartphone application has been implemented to allow the interaction with the platform, via a dedicated User Interface (UI). The lessons are inquiry-based and are structured so that the students are actively engaged in the learning process according to a learner centered approach. The project is jointly undertaken by the ESA Education Office and the ESA Automation and Robotics Section, with the support of the Control Systems Laboratory of the National Technical University of Athens. The development is taking place at the facilities of the Automation and Robotics Laboratory (ARL) of ESTEC, ESA’s European Space Research and Technology Centre in the Netherlands.

International Conference on Robotics and Automation (ICRA '15)

Terrain compliance is a critical parameter for the performance of legged locomotion. In this work... more Terrain compliance is a critical parameter for the performance of legged locomotion. In this work, a single actuator monopod robot hopping on a rough compliant terrain is considered. Based on our controller for flat compliant terrains, this paper introduces the necessary modifications, which allow the robot to tackle the disturbance of small inclinations. Using the developed method, the robot is examined on its performance to traverse rough terrains, while maintaining the goals of reaching a desired height and forward velocity. As the increased compliance and inclination alter the energy requirements from the controller actuator, the Cost of Transport index for a number of scenarios is studied. The correlation between terrain parameters and the CoT is presented, and useful conclusions, which can aid the understanding of the behavior of legged robots in realistic terrains are extracted.

Int. Conf. on Intelligent Robots and Systems (IROS ’14)

Legged locomotion is a rapidly advancing area in robotics, yet still a large number of open quest... more Legged locomotion is a rapidly advancing area in robotics, yet still a large number of open questions exist. This work focuses on the foot-terrain interaction and its effect on the motion of a one-legged system. This interaction is usually tackled by disregarding some of the effects of ground deformation like permanent deformation and compaction. Inspired by other areas of engineering, an impact dynamics model is developed, allowing a more thorough study of the behavior during fast dynamic walking. This approach can be regarded as a viscoplastic one. The monopod controller presented in previous work is extended to cope with deformable terrains, based on energy dissipation considerations, without requiring the knowledge of the ground parameters. Simulation results prove the validity of the theory presented.

International Conference on Robotics and Automation (ICRA '13)

One of the most demanding tasks for a robotic servicer is capturing a target. During this task, t... more One of the most demanding tasks for a robotic servicer is capturing a target. During this task, the mechanical systems can be subject to large forces for short duration (impacts). In space servicers, these impacts may render the capturing of a target impossible without the use of undesirable fuel-consuming maneuvers. This paper presents an approach for minimizing impact reactions, using the Center of Percussion (CoP), a characteristic of rigid bodies rotating around an axis. This work generalizes and delineates the exact requirements for its use. Application of CoP in multibody systems is demonstrated using the Newton-Euler Algorithm. Implementation guidelines are discussed. Simulations of a planar space robot system, and a three-dimensional PUMA-like manipulator on a satellite base confirm the benefit of using the CoP during tasks that include impacts.

International Conference on Intelligent Robots and Systems (IROS '11)

The importance of space robots in satellite servicing, in EVA assistance, in removing orbital deb... more The importance of space robots in satellite servicing, in EVA assistance, in removing orbital debris and in space exploration is growing, driven by space commercialization and exploration efforts. A successful deployment of such robots requires analytical and experimental task validation. With this aim, we present the main characteristics of the software and hardware space robot emulator developed at the NTUA.

Abstract-Refereed International Conference Proc. by Iosif S Paraskevas

66th International Astronautical Congress (IAC)

Exploitation of space must benefit from the latest advances in robotics. On-orbit servicing is a ... more Exploitation of space must benefit from the latest advances in robotics. On-orbit servicing is a clear candidate for the application of autonomous rendez-vous and docking mechanisms. However, during the last three decades most of the trials took place combining EVAs with telemanipulated robotic arms. The European Space Agency (ESA) considers that grasping and refueling are promising near-mid-term capabilities that could be performed by servicing spacecraft. Minimal add-ons on spacecraft to enhance their serviceability may protect them for a changing future in which satellite servicing may become mainstream.
ESA aims to conceive and promotestandard refueling provisions that can be installed in present and future European commercial GEO satellite platforms and scientific spacecraft. For this purpose ESA has started the ASSIST activity addressing the analysis, design and validation of internal provisions (such as modifications to fuel, gas, electrical, data architecture to allow servicing) and external provisions (such as integrated berthing fixtures with peripheral electrical, gas, liquid connectors, leak check systems and corresponding optical and radio markers for cooperative rendez-vous and docking). This refueling approach is being agreed with European industry (OHB, Thales Alenia Space) and expected to be consolidated with European commercial operators as a first step to become an international standard; this approach is also being considered for on-orbit servicing spacecraft, such as the SpaceTug, by Airbus DS.
This paper will detail the operational means, structure, geometry and accommodation of the system. Internal and external provisions will be designed with the minimum possible impact on the current architecture of GEO satellites, so that accommodating them in future satellites will not be seen as a major complication (both technical and in terms of costs), nor will it introduce additional risks in the development and commissioning of the satellite. End-effector and berthing fixtures are being designed in the range of few kilos and linear dimensions around 15cm. A central mechanical part is expected to perform first a soft docking followed by a motorized retraction ending in a hard docking phase using aligning pins. Mating and de-mating will be exhaustively analyzed to ensure robustness of operations. Leakage-free valves would allow for the transfer of fuel to the serviced spacecraft.
The validation of the ASSIST system through dedicated environmental tests in a vacuum chamber together with dynamic testing using an air-bearing table will allow for the demonstration of concept feasibility and its suitability for becoming a standard of the on-orbit space industry.

13th Symposium on Advanced Space Technologies in Robotics and Automation, (ASTRA ‘15)

Recent successes of missions such as the MSL and the Rosetta have increased the interest in the r... more Recent successes of missions such as the MSL and the Rosetta have increased the interest in the robotic exploration of other planets and asteroids. Although most of these missions envisage the use of rovers, legged robots have shown the potential to outperform wheeled vehicles on rough terrains in terms of speed and energy efficiency. In this paper, the x-MP controller presented in recent work, is used to evaluate the performance of a monopod robot under the effect of different gravitational fields and terrain types. The performance of the x-MP controller during regulating the robot motion on rough terrains and for the exploration of different types of planetary environments will be examined using simulations. Additionally using the Cost of Transport index, useful conclusions regarding the performance of legged robots for planetary exploration will be extracted.

13th Symposium on Advanced Space Technologies in Robotics and Automation, (ASTRA ‘15)

Space debris removal and mitigation using space robots are complex missions, which require extens... more Space debris removal and mitigation using space robots are complex missions, which require extensive analysis prior to launch. An important aspect during such a mission is the capturing task; any unsuccessful attempt may create more problems than solve. In this paper, the modelling of the impact docking between two multibody systems is studied. The effects of mass ratios on the resulting changes of relative velocities are analysed and discussed. An extension of the rigid body impact theory to multibody systems is developed, where the effect of system mass ratios to the change of the relative velocities is quantified, and its significance is discussed. Velocity requirements leading to a successful latching at first impact will be identified. Simulation results are presented that validate the proposed analytical approach. Future work is discussed.

12th Symposium on Advanced Space Technologies in Robotics and Automation, (ASTRA ‘13)

Leg compliance, gravity and ground have a significant impact on the performance and gait characte... more Leg compliance, gravity and ground have a significant impact on the performance and gait characteristics of a quadruped robot. This paper presents results obtained using a planar lumped parameter model of a quadruped robot and an extensive research scheme to determine optimum design parameters for a quadruped moving in different gravity environments. Hildebrand diagrams are used to classify quadruped robot gaits. In addition, an optimization procedure using either MathWorks fmincon or a Differential Evolutionary (DE) algorithm is employed to determine the optimum motion and robot physical parameters related to energy efficiency. Using “multiple gait graphs”, the effects of leg compliance, gravity and ground inclination are determined.

12th Symposium on Advanced Space Technologies in Robotics and Automation, (ASTRA ‘13)

To validate on-orbit servicing strategies, extensive sim- ulations and terrestrial emulation of r... more To validate on-orbit servicing strategies, extensive sim- ulations and terrestrial emulation of robotic systems are necessary. The NTUA has developed a Space Robot Emulator to emulate the operation of free-flying robotic servicers, as already presented in previous works. Until recently, the emulator consisted of one robot with two manipulators, capable of hovering over a flat granite ta- ble using air bearings, and of planar motion employing CO2 thrusters and a reaction wheel. To extend the capa- bilities of the Emulator, a second robot was developed with similar operational and design principles. In this paper, the mechatronic design of the robotic systems is presented. The limitations of the first robot and the de- velopments to overcome them in the second as well as some preliminary validation tests are presented.

In this paper, the development of an Orbital Robotics educational prototype platform is presented... more In this paper, the development of an Orbital Robotics educational prototype platform is presented, consisting of a hardware-developed physical system and an accompanying set of curriculum-based lessons (IB Physics curriculum) that target upper secondary students (16–18 years old target group). The platform was the outcome of a joint project between the European Space Agency and the National Technical University of Athens. The students use the hardware interactively, consisting of a bespoke space-emulating table and small satellite mockups. The lessons are inquiry-based and are structured so that the students are actively engaged in the learning process, according to a learner-centric approach. During the lessons, this platform allows students to acquire knowledge of the dynamics of space systems, as well as of the environmental conditions and physical constraints that characterize on-orbit operations. Students are able to manipulate the space robot (satellite) mockups performing basic tasks such as docking and landing, or grasping space debris. Additionally, a smartphone application has been implemented to allow the interaction with the platform, via a dedicated User Interface (UI).

NanoRobotics: Current Approaches and Techniques

24th Mediterranean Conference on Control and Automation (MED), Athens, Greece, 2016

6th International Conference on Robotics in Education (RiE ’15)

International Conference on Robotics and Automation (ICRA '15)

Int. Conf. on Intelligent Robots and Systems (IROS ’14)

International Conference on Robotics and Automation (ICRA '13)

International Conference on Intelligent Robots and Systems (IROS '11)

66th International Astronautical Congress (IAC)

Exploitation of space must benefit from the latest advances in robotics. On-orbit servicing is a ... more Exploitation of space must benefit from the latest advances in robotics. On-orbit servicing is a clear candidate for the application of autonomous rendez-vous and docking mechanisms. However, during the last three decades most of the trials took place combining EVAs with telemanipulated robotic arms. The European Space Agency (ESA) considers that grasping and refueling are promising near-mid-term capabilities that could be performed by servicing spacecraft. Minimal add-ons on spacecraft to enhance their serviceability may protect them for a changing future in which satellite servicing may become mainstream.
ESA aims to conceive and promotestandard refueling provisions that can be installed in present and future European commercial GEO satellite platforms and scientific spacecraft. For this purpose ESA has started the ASSIST activity addressing the analysis, design and validation of internal provisions (such as modifications to fuel, gas, electrical, data architecture to allow servicing) and external provisions (such as integrated berthing fixtures with peripheral electrical, gas, liquid connectors, leak check systems and corresponding optical and radio markers for cooperative rendez-vous and docking). This refueling approach is being agreed with European industry (OHB, Thales Alenia Space) and expected to be consolidated with European commercial operators as a first step to become an international standard; this approach is also being considered for on-orbit servicing spacecraft, such as the SpaceTug, by Airbus DS.
This paper will detail the operational means, structure, geometry and accommodation of the system. Internal and external provisions will be designed with the minimum possible impact on the current architecture of GEO satellites, so that accommodating them in future satellites will not be seen as a major complication (both technical and in terms of costs), nor will it introduce additional risks in the development and commissioning of the satellite. End-effector and berthing fixtures are being designed in the range of few kilos and linear dimensions around 15cm. A central mechanical part is expected to perform first a soft docking followed by a motorized retraction ending in a hard docking phase using aligning pins. Mating and de-mating will be exhaustively analyzed to ensure robustness of operations. Leakage-free valves would allow for the transfer of fuel to the serviced spacecraft.
The validation of the ASSIST system through dedicated environmental tests in a vacuum chamber together with dynamic testing using an air-bearing table will allow for the demonstration of concept feasibility and its suitability for becoming a standard of the on-orbit space industry.

13th Symposium on Advanced Space Technologies in Robotics and Automation, (ASTRA ‘15)

12th Symposium on Advanced Space Technologies in Robotics and Automation, (ASTRA ‘13)

On-Orbit Servicing plays a key role in the exploitation of space. To study related issues, the NT... more On-Orbit Servicing plays a key role in the exploitation of space. To study related issues, the NTUA has devel- oped a Space Robot Emulator for free-flying robotic servicers. In this emulator, the fusion of data from an overhead camera and on-board optical sensors is partic- ularly challenging. This becomes more complex due to the large time delay induced by the camera and image processing. To cope with these challenges, a Discrete Extended Kalman Filter (DEKF) is developed and ana- lyzed. Methods for reducing camera distortion errors and for calibration are discussed and simulation results are presented. Experiments validating the developed methodology are included.

11th International Symposium on Artificial Intelligence, Robotics and Automation in Space, (i-SAIRAS)

The development of space robotic systems presents design challenges and their commissioning requi... more The development of space robotic systems presents design challenges and their commissioning requires thorough studies and experiments. A planar space emulator has been developed to emulate the operation of free-flying robotic servicers and consists of two robotic systems that hover over a flat granite table. They have been designed to be lightweight, modular, multi- functional and analogous to space servicers. This paper presents the design challenges of the initial robot and their influence on the design of the new robot, the localization techniques, including sensors used and preliminary experimental results, and the fuel management techniques. The last two issues are important to both emulators and space robots, and correlate directly to realistic space robotics challenges.

11th ESA Workshop on Advanced Space Technologies for Robotics and Automation (ASTRA 2011)

Systematic miniaturization of Automation & Robotics (A&R) systems can result in more robust, less... more Systematic miniaturization of Automation & Robotics (A&R) systems can result in more robust, less power- intensive and less expensive systems with increased re- dundancy and enriched functionality. Due to the large and diverse markets, terrestrial micro/ nano technolo- gies (MNTs) are characterized by high performance, low development cost, reliability and sustainability of capabilities, making them ideal candidates for spinning- in in space A&R systems. These observations motivated this paper that presents (a) the findings of a thorough review and assessment of existing terrestrial MNTs that can be spinned-in to space A&R systems and (b) the systematic application of selected MNT to space A&R systems, resulting in roadmaps for space A&R systems.

10th ESA Workshop on Advanced Space Technologies for Robotics and Automation (ASTRA 2008)

The importance of space robots in satellite servicing, in EVA assistance, in removing orbital deb... more The importance of space robots in satellite servicing, in EVA assistance, in removing orbital debris and in space exploration is growing driven by space commercialization and exploration efforts. A successful deployment of such robots requires analytical and experimental task validation. With this aim, we present the main characteristics of the software and hardware space robot simulator developed at the NTUA.

1st Hellenic-European Student Space Science and Technology Symposium

The importance of simulators as testbeds for proposed space robotic systems is unquestionable in ... more The importance of simulators as testbeds for proposed space robotic systems is unquestionable in our days. In this paper, the NTUA approach on both software and hardware space robots simulators, is presented. The software simulator is fully parameterized in order to be capable to simulate any system that consists of a base and a number of serial appendages. The hardware simulator emulates 2D motion in zero gravity, and consists of a two-manipulator space robot moving on top of a granite table. The NTUA simulators are currently at the final stages of their development.

6th International ESA Conference on Guidance, Navigation and Control Systems

The necessity of robot manipulators in space is a one- way reality. The aim of this research work... more The necessity of robot manipulators in space is a one- way reality. The aim of this research work is to produce guidelines for grasping objects on orbit with the use of a space manipulator, such that manipulator reaction forces are minimized and therefore minimum disturbance forces are transmitted to its base. Impact reaction forces appear during the contact of two bodies. A methodology that uses the property of the percussion point of bodies that can rotate around a fixed axis is presented. The equations that describe the percussion point are developed. These functions are studied in depth to predict the best configuration of a manipulator during impact. A number of simulations are executed in order to examine the validity of these predictions, and guidelines suggesting optimal approach configurations are proposed.

2nd Panhellenic Conference on Robotics, 2010

Στην εργασία αυτή μελετάται η σχεδιαστική αναβάθμιση Διαστημικών Ρομποτικών Οχημάτων (ΔΡΟ – rover... more Στην εργασία αυτή μελετάται η σχεδιαστική αναβάθμιση Διαστημικών Ρομποτικών Οχημάτων (ΔΡΟ – rover) για εξερεύνηση πλανητών, μέσω της εισαγωγής επίγειων Μίκρο - Νάνο Τεχνολογιών (Μicro-Nano Technologies ή MNT) στα υποσυστήματά τους. Στόχος είναι η μείωση του όγκου, της μάζας και των απαιτήσεων ισχύος τους, με παράλληλη βελτίωση των λειτουργιών τους. Η εισαγωγή ΜΝΤ στο σχεδιασμό ΔΡΟ γίνεται με βάση ανάλυση η οποία υποδεικνύει τις προβληματικές περιοχές ανά υποσύστημα. Οι προτεινόμενες αντικαταστάσεις ανά υποσύστημα και οι κύριες αλλαγές στο σχεδιασμό, οδηγούν σε κατευθυντήριες γραμμές για το σχεδιασμό μελλοντικών ΔΡΟ.

1st Panhellenic Conference on Robotics, Athens

Η σπουδαιότητα των διαστημικών ρομποτικών συστημάτων σε περιπτώσεις όπως η επισκευή δορυφόρων, η ... more Η σπουδαιότητα των διαστημικών ρομποτικών συστημάτων σε περιπτώσεις όπως η επισκευή δορυφόρων, η βοήθεια σε αστροναύτες, η συλλογή και απομάκρυνση διαστημικών σκουπιδιών και η εξερεύνηση του διαστήματος και των πλανητών αυξάνει συνεχώς. Για την επιτυχή ανάπτυξη αυτών των ρομποτικών συστημάτων απαιτείται αναλυτική και πειραματική επαλήθευση της συμπεριφοράς τους σε περιβάλλοντα πολύ διαφορετικά από το επίγειο . Με αυτή την ανάγκη ως κατεύθυνση, σε αυτή την δημοσίευση παρουσιάζονται τα κύρια χαρακτηριστικά ενός συστήματος προσομοιωτή και εξομοιωτή διαστημικών ρομπότ που αναπτύχθηκε στο ΕΜΠ.