National Technical University of Athens - School of Mechanical Engineering
Control Systems Lab
Evangelos Papadopoulos Research Group

Ongoing Projects

[1] PREDATOR << Pre-Development of a Launch Adapter Ring Gripper >>




This project focuses on the grasping of an on-orbit satellite (Envisat) from its LAR. Based on the design of the Envisat LAR, the ENVISAT dimensions and mass, the chaser dimensions and dynamic properties, as well as its dimensions, the dynamic properties, and the motion capabilities of the DLR manipulator, a number of studies will be performed, aiming at the identification of potential capture strategies, and the requirements for the Griper that are necessary for performing the capturing task, as well as the range of admissible errors in positioning, speed, tolerance in force transmission etc.

[2] Biomechatronic Epp Upper Limb Prosthesis


Screenshot 2017 11 24 15 03 56


  • Funded by: FP& - Marie Curie
  • In cooperation with: -
  • Period: - December 2018
  • More Information: N/A
Upper limb prostheses have made considerable scientific progress in the last 20 years. This progress though is based on velocity control, which is not the best option for subconscious control. Extended Physiological Proprioception (EPP) provides position control and has been proven to be better as a control methodology for upper-limb prostheses than velocity control. EPP is difficult to implement since it requires: (a) the use of a harness or a post-amputation cineplasty surgical procedure and (b) a direct mechanical linkage (Bowden cable) between the control site and the prosthesis. For the above shortcomings, EPP was abandoned in the later years. We propose a biomechatronics-based master/slave topology which is going to provide an EPP-equivalent control but without the use of a harness, cineplasty, or Bowden cable. The proposed control uses an implanted tendon force and position transducer (TETRA) in series to specific muscles/tendons implanted at the time of amputation, providing an input source for the commanding signal. This signal - conditioned inside the body - is transmitted wirelessly to the Master Motor Controller which will drive the prosthesis proportionally to the commanding signal. Position, velocity and force sensors on the prosthesis will be inputs to the Slave Motor Controller which will provide as output a tactor proprioceptive feedback on the skin of the amputated limb proportional to the position, velocity and force of the prosthesis. 
This output from the tactor is going to be integrated by the skin mechanoreceptors of the skin of the amputee and will provide a proprioceptive feedback status of the prosthesis which will be integrated subconsciously by the human and taken into account at the next commanding signal stemming from the position, velocity and force of the contracted muscletendon complex. This architecture will provide an integrated EPP-equivalent control scheme for upper-limb prosthesis without the disadvantages of previous EPP configurations.
[3] Adaptable Wheels for Exploration




The problem of marrying large-surface contact with unobtrusive wheels can be solved by recurring to adaptable designs. Adaptable designs may provide a solution as the conflicting requirements on wheels are fortunately dissociated in operation. E.g. small wheels are needed when the rover is stowed (but not necessarily when it moves), small steering radii are needed in cluttered terrain (but not in soft terrain), large contact surface is needed in soft terrain (where steering radii can be large). Therefore it is possible to envisage that wheels with the ability to switch among a discrete number of geometric configurations could provide optimal performance in a rather large range of operational situations.
To date at ESA there has not been any R&D into adaptable wheels. Past R&D proposals were dismissed with the assumption that adaptability introduced unaffordable complexity. However there has never been any serious effort to quantify the "penalty" of complexity and also to analyse whether the penalty is commensurate to the benefits in performance.
A rover placed on the Moon pole, which has unpredictable soil characteristics, needs top performance to accomplish its challenging mission. It is quite possible that adaptable wheels may provide the level of performance that the rover require and at the same time increased probability of succeeding.
The activity shall:
1. Perform a state of the art search into the previously published concepts of adaptable wheels and analyse them with respect to potential of use in lunar pole scenario
2. Define requirements for adaptable wheels in a lunar pole scenario with attention to the operational phase/physical environment where the individual requirements are applicable. Define test scenarios.
3. Perform a trade off of the concepts to select the one that best accommodate the requirements also in consideration of the means used to actuate the adaptation
4. Prototype a set of AWE wheels and a set of conventional rigid wheels fulfilling the same requirements
5. Comparatively test the 2 wheel sets on a rover platform in the test scenarios previously defined.
NTUA-CSL is subcontractor in the project.
[4] COMRADE - Control Management of Robotics Active Debris Removal


IThe project addresses the definition, design coding, verification and validation of the mission vehicle management (MVM) software for the Active Debris Removal (ADR) mission. The activity comprises the control and management of the spacecraft in combination with the control and management of a robot arm used to grasp, stabilise and hold the target with the aim perform the controlled de-orbit The focus is in the increase of the compliance to the mission operational and technological constraints and the achievement of high levels of Reliability, Availability and Safety of the control software.


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