General information on the IRI research seminars

Seminars Jan - Jul 2018

Seminar 14-6-2018

Speaker: Federico Thomas ()
Title: A Reconfigurable Asymmetric 3-UPU Parallel Robot

Parallel robots with three UPU legs have received a lot of attention due to the possibility of assembling these legs so that the robot performs either a pure translational or a pure rotational motion. Nevertheless, some arrangements, despite their theoretical interest, are of doubtful practical utility due to their sensitivity to errors and the presence in their workspaces of mixed-modes that involve both translations and rotations. The introduction of some sort of asymmetry has been revealed of relevance to come up with more robust designs. In this context, we present an asymmetric 3-UPU robot, that can be reconfigured to work either as a translational or as a rotational robot by simply flipping upside down its moving platform.

Links: Speaker info, ReMAR18

Seminar 21-6-2018

Speaker: Soheil Sarabandi ()
Title: Accurate Computation of Quaternions from Rotation Matrices

The main non-singular alternative to 3×3 proper orthogonal matrices, for representing rotations in R^3, is quaternions. Thus, it is important to have reliable methods to pass from one representation to the other. While passing from a quaternion to the corresponding rotation matrix is given by Euler-Rodrigues formula, the other way round can be performed in many different ways. Although all of them are algebraically equivalent, their numerical behavior can be quite different. In 1978, Shepperd proposed a method for computing the quaternion corresponding to a rotation matrix which is considered the most reliable method to date. Shepperd’s method, thanks to a voting scheme between four possible solutions, always works far from formulation singularities. In this paper, we propose a new method which outperforms Shepperd’s method without increasing the computational cost.

Links: Speaker info, ARK18

Seminar 28-6-2018

Speaker: Ricard Bordalba ()
Title: Randomized Planning of Dynamic Motions Avoiding Forward Singularities

Forward singularities, also known as direct, or actuator sin- gularities, cause many problems to the planning and control of robot motions. They yield position errors and rigidity losses of the robot, and generate unbounded actions in typical control laws. To circumvent these issues, this paper proposes a randomized kinodynamic planner for com- puting trajectories avoiding such singularities. Given initial and final states for the robot, the planner attempts to connect them by means of a dynamically-feasible, singularity-free trajectory that also respects the force limits of the actuators. The performance of the strategy is illustrated in simulation by means of a parallel robot performing a highly-dynamic task.

Links: Speaker info, ARK18

Seminar 5-7-2018

Speaker: Anaís Garrell ()
Title: Human-Robot Interaction with UAVs: Challenges and Frontiers

Lately, there has been a growing interest in making autonomous robots able to interact with people. This challenging goal has opened many new research issues regarding the social capabilities robots should perform, for instance assisting people in public spaces or helping ageing people in homes. Furthermore, interest in flying-robots is growing significantly, and they are becoming more autonomous, meaning that their interaction and close collaboration with humans is the next step in terms of research and technical challenges. Therefore, this workshop deals with human-robot-interaction with UAVs, specifically the existing challenges and the frontiers found by researchers. Specifically, the main objectives of this workshop are two-fold. First, we will highlight recent developments in HRI with UAV's. We will compare state-of-the-art approaches and the current challenges researchers are working on. Moreover, we will introduce the frontiers authors have recently found during their investigations, encouraging discussions among participants to identify the current challenges and unsolved problems. Second, we will motivate our expert speakers to describe (1) which kind of tasks these social flying robots may solve and how they may assist and help people, and (2) how to open new avenues to build flying robots with greater capability to interact with people.

Links: Speaker info, ICRA-18, Workshop