22 research outputs found
Squash-Box Feasibility Driven Differential Dynamic Programming
Trabajo presentado en la IEEE/RSJ International Conference on Intelligent Robots and System, celebrada en Las Vegas (Estados Unidos), del 25 al 29 de octubre de 2020Recently, Differential Dynamic Programming (DDP) and other similar algorithms have become the solvers of choice when performing non-linear Model Predictive Control (nMPC) with modern robotic devices. The reason is that they have a lower computational cost per iteration when compared with off-the-shelf Non-Linear Programming (NLP) solvers, which enables its online operation. However, they cannot handle constraints, and are known to have poor convergence capabilities. In this paper, we propose a method to solve the optimal control problem with control bounds through a squashing function (i.e., a sigmoid, which is bounded by construction). It has been shown that a naive use of squashing functions damage the convergence rate. To tackle this, we first propose to add a quadratic barrier that avoids the difficulty of the plateau produced by the sigmoid. Second, we add an outer loop that adapts both the sigmoid and the barrier; it makes the optimal control problem with the squashing function converge to the original control-bounded problem. To validate our method, we present simulation results for different types of platforms including a multi-rotor, a biped, a quadruped and a humanoid robot
Borinot: an agile torque-controlled robot for hybrid flying and contact loco-manipulation (workshop version)
This paper introduces Borinot, an open-source flying robotic platform
designed to perform hybrid agile locomotion and manipulation. This platform
features a compact and powerful hexarotor that can be outfitted with
torque-actuated extremities of diverse architecture, allowing for whole-body
dynamic control. As a result, Borinot can perform agile tasks such as
aggressive or acrobatic maneuvers with the participation of the whole-body
dynamics. The extremities attached to Borinot can be utilized in various ways;
during contact, they can be used as legs to create contact-based locomotion, or
as arms to manipulate objects. In free flight, they can be used as tails to
contribute to dynamics, mimicking the movements of many animals. This allows
for any hybridization of these dynamic modes, like the jump-flight of chicken
and locusts, making Borinot an ideal open-source platform for research on
hybrid aerial-contact agile motion. To demonstrate the key capabilities of
Borinot, we have fitted a planar 2DoF arm and implemented whole-body
torque-level model-predictive-control. The result is a capable and adaptable
platform that, we believe, opens up new avenues of research in the field of
agile robotics.Comment: 2 pages + references. Workshop on agile robotics, ICRA 202
Full-Body Torque-Level Non-linear Model Predictive Control for Aerial Manipulation
Non-linear model predictive control (nMPC) is a powerful approach to control
complex robots (such as humanoids, quadrupeds, or unmanned aerial manipulators
(UAMs)) as it brings important advantages over other existing techniques. The
full-body dynamics, along with the prediction capability of the optimal control
problem (OCP) solved at the core of the controller, allows to actuate the robot
in line with its dynamics. This fact enhances the robot capabilities and
allows, e.g., to perform intricate maneuvers at high dynamics while optimizing
the amount of energy used. Despite the many similarities between humanoids or
quadrupeds and UAMs, full-body torque-level nMPC has rarely been applied to
UAMs.
This paper provides a thorough description of how to use such techniques in
the field of aerial manipulation. We give a detailed explanation of the
different parts involved in the OCP, from the UAM dynamical model to the
residuals in the cost function. We develop and compare three different nMPC
controllers: Weighted MPC, Rail MPC, and Carrot MPC, which differ on the
structure of their OCPs and on how these are updated at every time step. To
validate the proposed framework, we present a wide variety of simulated case
studies. First, we evaluate the trajectory generation problem, i.e., optimal
control problems solved offline, involving different kinds of motions (e.g.,
aggressive maneuvers or contact locomotion) for different types of UAMs. Then,
we assess the performance of the three nMPC controllers, i.e., closed-loop
controllers solved online, through a variety of realistic simulations. For the
benefit of the community, we have made available the source code related to
this work.Comment: Submitted to Transactions on Robotics. 17 pages, 16 figure
Hybrid visual servoing with hierarchical task composition for aerial manipulation
© 2016 IEEE. Personal use of this material is permitted. Permission from IEEE must be obtained for all other uses, in any current or future media, including reprinting/republishing this material for advertising or promotional purposes, creating new collective works, for resale or redistribution to servers or lists, or reuse of any copyrighted component of this work in other works.In this paper a hybrid visual servoing with a hierarchical task-composition control framework is described for aerial manipulation, i.e. for the control of an aerial vehicle endowed with a robot arm. The proposed approach suitably combines into a unique hybrid-control framework the main benefits of both image-based and position-based control schemes. Moreover, the underactuation of the aerial vehicle has been explicitly taken into account in a general formulation, together with a dynamic smooth activation mechanism. Both simulation case studies and experiments are presented to demonstrate the performance of the proposed technique.Peer ReviewedPostprint (author's final draft
The AEROARMS Project: Aerial Robots with Advanced Manipulation Capabilities for Inspection and Maintenance
This article summarizes new aerial robotic manipulation technologies and methods—aerial robotic manipulators with dual arms and multidirectional thrusters—developed in the AEROARMS project for outdoor industrial inspection and maintenance (I&M). Our report deals with the control systems, including the control of the interaction forces and the compliance the teleoperation, which uses passivity to tackle the tradeoff between stability and performance the perception methods for localization, mapping, and inspection the planning methods, including a new control-aware approach for aerial manipulation.
Finally, we describe a novel industrial platform with multidirectional thrusters and a new arm design to increase the robustness in industrial contact inspections. In addition, the lessons learned in applying the platform to outdoor aerial manipulation for I&M are pointed out
FamÃlies botà niques de plantes medicinals
Facultat de Farmà cia, Universitat de Barcelona. Ensenyament: Grau de Farmà cia, Assignatura: Botà nica Farmacèutica, Curs: 2013-2014, Coordinadors: Joan Simon, Cèsar Blanché i
Maria Bosch.Els materials que aquà es presenten són els recull de 175 treballs d’una famÃlia botà nica d’interès medicinal realitzats de manera individual. Els treballs han estat realitzat
per la totalitat dels estudiants dels grups M-2 i M-3 de l’assignatura Botà nica Farmacèutica
durant els mesos d’abril i maig del curs 2013-14. Tots els treballs s’han dut a terme a través de la plataforma de GoogleDocs i han estat tutoritzats pel professor de l’assignatura i revisats i finalment co-avaluats entre els propis estudiants. L’objectiu principal de l’activitat ha estat fomentar l’aprenentatge autònom i col·laboratiu en Botà nica farmacèutica