61 research outputs found
Oscillation Damping Control of Pendulum-like Manipulation Platform using Moving Masses
This paper presents an approach to damp out the oscillatory motion of the
pendulum-like hanging platform on which a robotic manipulator is mounted. To
this end, moving masses were installed on top of the platform. In this paper,
asymptotic stability of the platform (which implies oscillation damping) is
achieved by designing reference acceleration of the moving masses properly. A
main feature of this work is that we can achieve asymptotic stability of not
only the platform, but also the moving masses, which may be challenging due to
the under-actuation nature. The proposed scheme is validated by the simulation
studies.Comment: IFAC Symposium on Robot Control (SYROCO) 201
Asynchronous Behavior Trees with Memory aimed at Aerial Vehicles with Redundancy in Flight Controller
Complex aircraft systems are becoming a target for automation. For successful
operation, they require both efficient and readable mission execution system.
Flight control computer (FCC) units, as well as all important subsystems, are
often duplicated. Discrete nature of mission execution systems does not allow
small differences in data flow among redundant FCCs which are acceptable for
continuous control algorithms. Therefore, mission state consistency has to be
specifically maintained. We present a novel mission execution system which
includes FCC state synchronization. To achieve this result we developed a new
concept of Asynchronous Behavior Tree with Memory and proposed a state
synchronization algorithm. The implemented system was tested and proven to work
in a real-time simulation of High Altitude Pseudo Satellite (HAPS) mission.Comment: Accepted to IEEE/RSJ International Conference on Intelligent Robots
and Systems (IROS 2019), IEEE copyrigh
Passive Compliance Control of Aerial Manipulators
This paper presents a passive compliance control for aerial manipulators to
achieve stable environmental interactions. The main challenge is the absence of
actuation along body-planar directions of the aerial vehicle which might be
required during the interaction to preserve passivity. The controller proposed
in this paper guarantees passivity of the manipulator through a proper choice
of end-effector coordinates, and that of vehicle fuselage is guaranteed by
exploiting time domain passivity technique. Simulation studies validate the
proposed approach.Comment: IEEE/RSJ International Conference on Intelligent Robots and Systems
(IROS) 201
Whole-Body Bilateral Teleoperation of a Redundant Aerial Manipulator
Attaching a robotic manipulator to a flying base allows for significant
improvements in the reachability and versatility of manipulation tasks. In
order to explore such systems while taking advantage of human capabilities in
terms of perception and cognition, bilateral teleoperation arises as a
reasonable solution. However, since most telemanipulation tasks require visual
feedback in addition to the haptic one, real-time (task-dependent) positioning
of a video camera, which is usually attached to the flying base, becomes an
additional objective to be fulfilled. Since the flying base is part of the
kinematic structure of the robot, if proper care is not taken, moving the video
camera could undesirably disturb the end-effector motion. For that reason, the
necessity of controlling the base position in the null space of the
manipulation task arises. In order to provide the operator with meaningful
information about the limits of the allowed motions in the null space, this
paper presents a novel haptic concept called Null-Space Wall. In addition, a
framework to allow stable bilateral teleoperation of both tasks is presented.
Numerical simulation data confirm that the proposed framework is able to keep
the system passive while allowing the operator to perform time-delayed
telemanipulation and command the base to a task-dependent optimal pose.Comment: to be published in 2020 IEEE International Conference on Robotics and
Automation (ICRA
Multi-DoF Time Domain Passivity Approach Based Drift Compensation for Telemanipulation
When, in addition to stability, position synchronization is also desired in
bilateral teleoperation, Time Domain Passivity Approach (TDPA) alone might not
be able to fulfill the desired objective. This is due to an undesired effect
caused by admittance type passivity controllers, namely position drift.
Previous works focused on developing TDPA-based drift compensation methods to
solve this issue. It was shown that, in addition to reducing drift, one of the
proposed methods was able to keep the force signals within their normal range,
guaranteeing the safety of the task. However, no multi-DoF treatment of those
approaches has been addressed. In that scope, this paper focuses on providing
an extension of previous TDPA-based approaches to multi-DoF Cartesian-space
teleoperation. An analysis of the convergence properties of the presented
method is also provided. In addition, its applicability to multi-DoF devices is
shown through hardware experiments and numerical simulation with round-trip
time delays up to 700 ms.Comment: 2019 19th International Conference on Advanced Robotics (ICAR
Model Predictive Control for a Small Scale Unmanned Helicopter
Kinematical and dynamical equations of a small scale unmanned helicoper are presented in the paper. Based on these equations a model predictive control (MPC) method is proposed for controlling the helicopter. This novel method allows the direct accounting for the existing time delays which are used to model the dynamics of actuators and aerodynamics of the main rotor. Also the limits of the actuators are taken into the considerations during the controller design. The proposed control algorithm was verified in real flight experiments where good perfomance was shown in postion control mode
Modelado y control en vuelo estacionario de helicópteros autónomos con cable de fijación a tierra
Los helicópteros son conocidos por sus capacidades de vuelo estacionario (maniobra conocida como hovering), despegue y
aterrizaje vertical. Sin embargo, la ejecución de la maniobra de hovering puede verse afectada seriamente por perturbaciones como
ráfagas de viento. Lo anterior es más significativo en el caso de helicópteros a escala, que son comúnmente adoptados como
plataformas para el desarrollo de vehículos aéreos no tripulados. Para solventar las dificultades anteriores y conseguir maniobras de
hovering más estables es posible emplear una configuración consistente en un helicóptero autónomo, un cable de fijación a tierra
y un sistema de control que ajusta la tensión en el cable. En este artículo, además de incluir los pasos necesarios para obtener un
modelo detallado del sistema, se presenta un análisis de los beneficios inherentes a la configuración con cable, así como el esquema
general para el diseño de estrategias de control. A manera de ilustración, se incluyen simulaciones comparativas con perturbaciones
de viento generadas artificialmenteJunta de Andalucía (España) RURBAN P09-TIC-5121Secretaría de Estado de Investigación, Desarrollo e Innovación del gobierno de España Plan Nacional de I+D+i CLEAR DPI2011-28937-C02-01Comisión Europea EC-SAFEMOBIL FP7-ICT-2011-
Vision Aided Automatic Landing System for Fixed Wing UAV
Abstract-In this paper, we present a multi-sensor system for automatic landing of fixed wing UAVs. The system is composed of a high precision aircraft controller and a vision module which is currently used for detection and tracking of runways. Designing the system we paid special attention to its robustness. The runway detection algorithm uses a maximum amount of information in images and works with high level geometrical models. It allows detecting a runway under different weather conditions even if only a small part is visible in the image. In order to increase landing reliability under sub-optimal wind conditions, an additional loop was introduced into the altitude controller. All control and image processing is performed onboard. The system has been successfully tested in flight experiments with two different fixed wing platforms at various weather conditions, in summer, fall and winter
Closed-Loop Behavior of an Autonomous Helicopter Equipped with a Robotic Arm for Aerial Manipulation Tasks
This paper is devoted to the control of aerial robots interacting physically with objects in the environment and
with other aerial robots. The paper presents a controller for the particular case of a small‐scaled autonomous helicopter equipped with a robotic arm for aerial manipulation.
Two
types
of
influences
are
imposed
on
the
helicopter
from
a
manipulator:
coherent
and
non
‐
coherent
influence.
In
the
former
case,
the
forces
and
torques
imposed
on
the
helicopter
by
the
manipulator
change
with
frequencies
close
to
those
of
the
helicopter
movement.
The
paper
shows
that
even
small
interaction
forces
imposed
on
the
fuselage
periodically
in
proper
phase
could
yield
to
low
frequency
instabilities
and
oscillations,
so
called
phase
circle
- …