In this paper we present a method for automatically planning robust optimal
paths for a group of robots that satisfy a common high level mission
specification. Each robot's motion in the environment is modeled as a weighted
transition system, and the mission is given as a Linear Temporal Logic (LTL)
formula over a set of propositions satisfied by the regions of the environment.
In addition, an optimizing proposition must repeatedly be satisfied.
Communication among microscopic robots (nanorobots) can coordinate their
activities for biomedical tasks. The feasibility of in vivo ultrasonic
communication is evaluated for micron-size robots broadcasting into various
types of tissues. Frequencies between 10MHz and 300MHz give the best tradeoff
between efficient acoustic generation and attenuation for communication over
distances of about 100 microns.
Attempts to install a rotating tool at the end of a robot arm
poly-articulated date back twenty years, but these robots were not designed for
that. Indeed, two essential features are necessary for machining: high rigidity
and precision in a given workspace. The experimental results presented are the
dynamic identification of a poly-articulated robot equipped with an integrated
spindle. This study aims to highlight the influence of the geometric
configuration of the robot arm on the overall stiffness of the system.
The six axis robots are widely used in automotive industry for their good
repeatability (as defined in the ISO92983) (painting, welding, mastic
deposition, handling etc.). In the aerospace industry, robot starts to be used
for complex applications such as drilling, riveting, fiber placement, NDT, etc.
Given the positioning performance of serial robots, precision applications
require usually external measurement device with complexes calibration
procedure in order to reach the precision needed.
This diploma thesis describes the theoretical bases, the conception of the
module and the final result of the development process in application. for the
environment logging with a small mobile robot for interiors should be sketched
an economical alternative to the expensive laser scanners. the structure, color
or the material of the objects in the radius of action, as well as the
environment brightness and illuminating are to have thereby no influence on the
results of measurement.
RGB-D cameras, which give an RGB image to- gether with depths, are becoming
increasingly popular for robotic perception. In this paper, we address the task
of detecting commonly found objects in the 3D point cloud of indoor scenes
obtained from such cameras. Our method uses a graphical model that captures
various features and contextual relations, including the local visual
appearance and shape cues, object co-occurence relationships and geometric
relationships.
Creation of devices and mechanisms which help people has a long history.
Their inventors always targeted practical goals such as irrigation, harvesting,
devices for construction sites, measurement, and, last but not least, military
tasks for different mechanical and later mechatronic systems. Development of
such assisting mechanisms counts back to Greek engineering, came through Middle
Ages and led finally in XIX and XX centuries to autonomous devices, which we
call today "Robots".
Awareness and self-awareness are two different notions related to knowing the
environment and itself. In a general context, the mechanism of self-awareness
belongs to a class of co-called "self-issues" (self-* or self-star):
self-adaptation, self-repairing, self-replication, self-development or
self-recovery. The self-* issues are connected in many ways to adaptability and
evolvability, to the emergence of behavior and to the controllability of
long-term developmental processes.
Cooperation and competition among stand-alone swarm agents increase
collective fitness of the whole system. A principally new kind of collective
systems is demonstrated by some bacteria and fungi, when they build symbiotic
organisms. Symbiotic life forms emerge new functional and self-developmental
capabilities, which allow better survival of swarm agents in different
environments. In this paper we consider energy foraging scenario for two
robotic species, swarm robots and symbiotic robot organism.
The use of mobile robots is being popular over the world mainly for
autonomous explorations in hazardous/ toxic or unknown environments. This
exploration will be more effective and efficient if the explorations in unknown
environment can be aided with the learning from past experiences. Currently
reinforcement learning is getting more acceptances for implementing learning in
robots from the system-environment interactions. This learning can be
implemented using the concept of both single-agent and multiagent.
Homogeneity and heterogeneity represent a well-known trade-off in the design
of modular robot systems. This work addresses the heterogeneity concept, its
rationales, design choices and performance evaluation. We introduce challenges
for self-reconfigurable systems, show advances of mechatronic and software
design of heterogeneous platforms and discuss experiments, which intend to
demonstrate usability and performance of this system.
We consider the problem of finding a control policy for a Markov Decision
Process (MDP) to maximize the probability of reaching some states while
avoiding some other states. This problem is motivated by applications in
robotics, where such problems naturally arise when probabilistic models of
robot motion are required to satisfy temporal logic task specifications. We
transform this problem into a Stochastic Shortest Path (SSP) problem and
develop a new approximate dynamic programming algorithm to solve it.
In the area of bipedal locomotion, the spring loaded inverted pendulum (SLIP)
model has been proposed as a unified framework to explain the dynamics of a
wide variety of gaits. In this paper, we present a novel analysis of the
mathematical model and its dynamical properties. We use the perspective of
hybrid dynamical systems to study the dynamics and define concepts such as
partial stability and viability. With this approach, on the one hand, we
identified stable and unstable regions of locomotion.
Common estimation algorithms, such as least squares estimation or the Kalman
filter, operate on a state in a state space S that is represented as a
real-valued vector. However, for many quantities, most notably orientations in
3D, S is not a vector space, but a so-called manifold, i.e. it behaves like a
vector space locally but has a more complex global topological structure. For
integrating these quantities, several ad-hoc approaches have been proposed.
In this paper we present a method for automatically planning optimal paths
for a group of robots that satisfy a common high level mission specification.
Each robot's motion in the environment is modeled as a weighted transition
system. The mission is given as a Linear Temporal Logic formula. In addition,
an optimizing proposition must repeatedly be satisfied. The goal is to minimize
the maximum time between satisfying instances of the optimizing proposition.
Our method is guaranteed to compute an optimal set of robot paths.
During the last decade, sampling-based path planning algorithms, such as
Probabilistic RoadMaps (PRM) and Rapidly-exploring Random Trees (RRT), have
been shown to work well in practice and possess theoretical guarantees such as
probabilistic completeness. However, little effort has been devoted to the
formal analysis of the quality of the solution returned by such algorithms,
e.g., as a function of the number of samples.
The concealment of amputation through prosthesis usage can shield an amputee
from social stigma and help improve the emotional healing process especially at
the early stages of hand or finger loss. However, the traditional techniques in
prosthesis fabrication defy this as the patients need numerous visits to the
clinics for measurements, fitting and follow-ups. This paper presents a method
for constructing a prosthetic finger through online collaboration with the
designer.
Current progresses in home automation and service robotic environment have
highlighted the need to develop interoperability mechanisms that allow a
standard communication between the two systems. During the development of the
DHCompliant protocol, the problem of locating mobile devices in an indoor
environment has been investigated. The communication of the device with the
location service has been carried out to study the time delay that web services
offer in front of the sockets.
We present controllers that enable mobile robots to persistently monitor or
sweep a changing environment. The changing environment is modeled as a field
which grows in locations that are not within range of a robot, and decreases in
locations that are within range of a robot. We assume that the robots travel on
given closed paths. The speed of each robot along its path is controlled to
prevent the field from growing unbounded at any location. We consider the space
of speed controllers that can be parametrized by a finite set of basis
functions.
The paper presents a methodology to enhance the stiffness analysis of
parallel manipulators with parallelogram-based linkage. It directly takes into
account the influence of the external loading and allows computing both the
non-linear ``load-deflection" relation and relevant rank-deficient stiffness
matrix. An equivalent bar-type pseudo-rigid model is also proposed to describe
the parallelogram stiffness by means of five mutually coupled virtual springs.
The contributions of this paper are highlighted with a parallelogram-type
linkage used in a manipulator from the Orthoglide family.
Virtual human simulation integrated into virtual reality applications is
mainly used for virtual representation of the user in virtual environment or
for interactions between the user and the virtual avatar for cognitive tasks.
In this paper, in order to prevent musculoskeletal disorders, the integration
of virtual human simulation and VR application is presented to facilitate
physical ergonomic evaluation, especially for physical fatigue evaluation of a
given population. Immersive working environments are created to avoid expensive
physical mock-up in conventional evaluation methods.
This paper focuses on the performance evaluation of the parallel manipulators
for milling of composite materials. For this application the most significant
performance measurements, which denote the ability of the manipulator for the
machining are defined. In this case, optimal synthesis task is solved as a
multicriterion optimization problem with respect to the geometric, kinematic,
kinetostatic, elastostostatic, dynamic properties. It is shown that stiffness
is an important performance factor.
The paper presents a methodology for the enhanced stiffness analysis of
parallel manipulators with internal preloading in passive joints. It also takes
into account influence of the external loading and allows computing both the
non-linear "load-deflection" relation and the stiffness matrices for any given
location of the end-platform or actuating drives.
We propose distributed algorithms to automatically deploy a group of mobile
robots to partition and provide coverage of a non-convex environment. To handle
arbitrary non-convex environments, we represent them as connected graphs. Our
partitioning and coverage algorithm requires only short-range, unreliable
pairwise "gossip" communication among the agents. The algorithm has two
components: (1) a motion protocol to ensure that each robot communicates with
its neighbors at least sporadically, and (2) a pairwise partitioning rule to
update territory ownership whenever two robots communicate.
Smart homes are becoming more popular, as every day a new home appliance can
be digitally controlled. Smart Digital Homes are using a server to make
interaction with all the possible devices in one place, on a computer or
webpage. In this paper we designed and implemented a mobile application using
Windows Mobile platform that can connect to the controlling server of a Smart
Home and grants the access to the Smart Home devices and robots everywhere
possible. UML diagrams are presented to illustrate the application design
process.
Most commercial manufacturers of industrial robots require their robots to be
programmed in a proprietary language tailored to the domain - a typical
domain-specific language (DSL). However, these languages oftentimes suffer from
shortcomings such as controller-specific design, limited expressiveness and a
lack of extensibility. For that reason, we developed the extensible Robotics
API for programming industrial robots on top of a general-purpose language.
Although being a very flexible approach to programming industrial robots, a
fully-fledged language can be too complex for simple tasks.
Sampling-based motion planners are an effective means for generating
collision-free motion paths. However, the quality of these motion paths, with
respect to different quality measures such as path length, clearance,
smoothness or energy, is often notoriously low. This problem is accentuated in
the case of non-holonomic sampling-based motion planning, in which the space of
feasible motion trajectories is restricted.
Off-line robot dynamic identification methods are mostly based on the use of
the inverse dynamic model, which is linear with respect to the dynamic
parameters. This model is sampled while the robot is tracking reference
trajectories that excite the system dynamics. This allows using linear
least-squares techniques to estimate the parameters. The efficiency of this
method has been proved through the experimental identification of many
prototypes and industrial robots.
This article presents a distributed algorithm for a group of robotic agents
with omnidirectional vision to deploy into nonconvex polygonal environments
with holes. Agents begin deployment from a common point, possess no prior
knowledge of the environment, and operate only under line-of-sight sensing and
communication. The objective of the deployment is for the agents to achieve
full visibility coverage of the environment while maintaining line-of-sight
connectivity with each other.
We report a globally-optimal approach to robotic path planning under
uncertainty, based on the theory of quantitative measures of formal languages.
A significant generalization to the language-measure-theoretic path planning
algorithm $\nustar$ is presented that explicitly accounts for average dynamic
uncertainties and estimation errors in plan execution.
In this paper we present a method for automatically generating optimal robot
trajectories satisfying high level mission specifications. The motion of the
robot in the environment is modeled as a general transition system, enhanced
with weighted transitions. The mission is specified by a general linear
temporal logic formula. In addition, we require that an optimizing proposition
must be repeatedly satisfied. The cost function that we seek to minimize is the
maximum time between satisfying instances of the optimizing proposition.
Most cognitive architectures rely on discrete representation, both in space
(e.g., objects) and in time (e.g., events). However, a robot interaction with
the world is inherently continuous, both in space and in time. The segmentation
of the stream of perceptual inputs a robot receives into discrete and
meaningful events poses as a challenge in bridging the gap between internal
cognitive representations, and the external world.
This work, inspired by the idea of "Computing with Words and Perceptions"
proposed by Zadeh in 2001, focuses on how to transform measurements into
perceptions for the problem of map building by Autonomous Mobile Robots. We
propose to model the perceptions obtained from sonar-sensors as two grid maps:
one for obstacles and another for empty spaces. The rules used to build and
integrate these maps are expressed by linguistic descriptions and modeled by
fuzzy rules.
Virtual human techniques have been used a lot in industrial design in order
to consider human factors and ergonomics as early as possible. The physical
status (the physical capacity of virtual human) has been mostly treated as
invariable in the current available human simulation tools, while indeed the
physical capacity varies along time in an operation and the change of the
physical capacity depends on the history of the work as well. Virtual Human
Status is proposed in this paper in order to assess the difficulty of manual
handling operations, especially from the physical perspective.
This paper is concerned with designing self-driven fitness functions for
Embedded Evolutionary Robotics. The proposed approach considers the entropy of
the sensori-motor stream generated by the robot controller. This entropy is
computed using unsupervised learning; its maximization, achieved by an on-board
evolutionary algorithm, implements a "curiosity instinct", favouring
controllers visiting many diverse sensori-motor states (sms). Further, the set
of sms discovered by an individual can be transmitted to its offspring, making
a cultural evolution mode possible.
An accurate motion model is an important component in modern-day robotic
systems, but building such a model for a complex system often requires an
appreciable amount of manual effort. In this paper we present a motion model
representation, the Dynamic Gaussian Mixture Model (DGMM), that alleviates the
need to manually design the form of a motion model, and provides a direct means
of incorporating auxiliary sensory data into the model.
The linear complementarity problem is to find vector $z$ in $\mathrm{IR}^{n}$
satisfying $z^{T}(Mz+q)=0$, $Mz+q\geqslant0,$ $z\geqslant0$, where $M$ as a
matrix and $q$ as a vector, are given data; this problem becomes in present the
subject of much important research because it arises in many areas and it
includes important fields, we cite for example the linear and nonlinear
programming, the convex quadratic programming and the variational inequalities
problems, ...
... This paper is to describe exploratory research on the design of a modular
autonomous mobile robot controller. The controller incorporates a fuzzy logic
[8] [9] approach for steering and speed control [37], a FL approach for
ultrasound sensing and an overall expert system for guidance. The advantages of
a modular system are related to portability and transportability, i.e. any
vehicle can become autonomous with minimal modifications.
This article is devoted to the stabilization of two underactuated planar
systems, the well-known straight beam-and-ball system and an original circular
beam-and-ball system. The feedback control for each system is designed, using
the Jordan form of its model, linearized near the unstable equilibrium. The
limits on the voltage, fed to the motor, are taken into account explicitly. The
straight beam-and-ball system has one unstable mode in the motion near the
equilibrium point. The proposed control law ensures that the basin of
attraction coincides with the controllability domain.
FastSLAM is a framework for simultaneous localization using a
Rao-Blackwellized particle filter. In FastSLAM, particle filter is used for the
mobile robot pose (position and orientation) estimation, and an Extended Kalman
Filter (EKF) is used for the feature location's estimation. However, FastSLAM
degenerates over time. This degeneracy is due to the fact that a particle set
estimating the pose of the robot loses its diversity. One of the main reasons
for loosing particle diversity in FastSLAM is sample impoverishment.
A smart Unmanned Ground Vehicle (UGV) is designed and developed for some
application specific missions to operate predominantly in hazardous
environments. In our work, we have developed a small and lightweight vehicle to
operate in general cross-country terrains in or without daylight. The UGV can
send visual feedbacks to the operator at a remote location. Onboard infrared
sensors can detect the obstacles around the UGV and sends signals to the
operator.
This article synthezises the most important results on the kinematics of
cuspidal manipulators i.e. nonredundant manipulators that can change posture
without meeting a singularity. The characteristic surfaces, the uniqueness
domains and the regions of feasible paths in the workspace are defined. Then,
several sufficient geometric conditions for a manipulator to be noncuspidal are
enumerated and a general necessary and sufficient condition for a manipulator
to be cuspidal is provided. An explicit DH-parameter-based condition for an
orthogonal manipulator to be cuspidal is derived.
The paper presents the position analysis of a spatial structure composed of
two platforms mutually connected by one RRP and three SS serial kinematic
chains, where R, P, and S stand for revolute, prismatic, and spherical
kinematic pair respectively. A set of three compatibility equations is laid
down that, following algebraic elimination, results in a 28th-order univariate
algebraic equation, which in turn provides the addressed problem with 28
solutions in the complex domain.
Sampling-based motion planners are effective means for generating
collision-free motion paths. However, the quality of these motion paths is
often notoriously low, especially in high-dimensional configuration spaces
(with respect to quality measures such as path length, clearance, smoothness or
energy). We introduce a simple and effective algorithm for merging an arbitrary
number of input motion paths into a hybrid output path of superior quality,
using a generalized formulation of path quality.
Series Elastic Actuators provide many benefits in force control of robots in
unconstrained environments. These benefits include high force fidelity,
extremely low impedance, low friction, and good force control bandwidth. Series
Elastic Actuators employ a novel mechanical design architecture which goes
against the common machine design principal of "stiffer is better". A compliant
element is placed between the gear train and driven load to intentionally
reduce the stiffness of the actuator.
The paper focuses on the enhanced stiffness modeling of robotic manipulators
by taking into account influence of the external force/torque acting upon the
end point. It implements the virtual joint technique that describes the
compliance of manipulator elements by a set of localized six-dimensional
springs separated by rigid links and perfect joints.
The paper proposes a novel approach for the geometrical model calibration of
quasi-isotropic parallel kinematic mechanisms of the Orthoglide family. It is
based on the observations of the manipulator leg parallelism during motions
between the specific test postures and employs a low-cost measuring system
composed of standard comparator indicators attached to the universal magnetic
stands.
It was shown recently that parallel manipulators with several inverse
kinematic solutions have the ability to avoid parallel singularities [Chablat
1998a] and self-collisions [Chablat 1998b] by choosing appropriate joint
configurations for the legs. In effect, depending on the joint configurations
of the legs, a given configuration of the end-effector may or may not be free
of singularity and collision.
This paper deals with the optimal path placement for a manipulator based on
energy consumption. It proposes a methodology to determine the optimal location
of a given test path within the workspace of a manipulator with minimal
electric energy used by the actuators while taking into account the geometric,
kinematic and dynamic constraints. The proposed methodology is applied to the
Orthoglide~3-axis, a three-degree-of-freedom translational parallel kinematic
machine (PKM), as an illustrative example.
This paper introduces a methodology to analyze geometrically the
singularities of manipulators, of which legs apply both actuation forces and
constraint moments to their moving platform. Lower-mobility parallel
manipulators and parallel manipulators, of which some legs do not have any
spherical joint, are such manipulators. The geometric conditions associated
with the dependency of six Pl\"ucker vectors of finite lines or lines at
infinity constituting the rows of the inverse Jacobian matrix are formulated
using Grassmann-Cayley Algebra.
In several fields like aeronautics, die and automotive, the machining of the
parts is done more and more on high speed machines tools. Today, the offer for
purchasing these machine tools is very wide. This situation poses the problem
of the judicious and objective choice meeting industrial needs that must be
necessary well expressed. The choice remains difficult insofar as the technical
data provided to the customers by the manufacturers of machine tools are
insufficient as well quantitatively as qualitatively.
This paper will provide a method to decompose forging dies for machining
planning in the case of high speed machining finishing operations. This method
lies on a machining feature approach model presented in the following paper.
The two main decomposition phases, called Basic Machining Features Extraction
and Process Planning Generation, are presented. These two decomposition phases
integrates machining resources models and expert machining knowledge to provide
an outstanding process planning.
Nowadays high speed machining (HSM) machine tool combines productivity and
part quality. So mould and die maker invested in HSM. Die and mould features
are more and more complex shaped. Thus, it is difficult to choose the best
machining strategy according to part shape. Geometrical analysis of machining
features is not sufficient to make an optimal choice. Some research show that
security, technical, functional and economical constrains must be taken into
account to elaborate a machining strategy.
Today's forging die manufacturing process must be adapted to several
evolutions in machining process generation: CAD/CAM models, CAM software
solutions and High Speed Machining (HSM). In this context, the adequacy between
die shape and HSM process is in the core of machining preparation and process
planning approaches. This paper deals with an original approach of machining
preparation integrating this adequacy in the main tasks carried out.
Today's High-Speed Machining (HSM) machine tool combines productivity and
part quality. The difficulty inherent in HSM operations lies in understanding
the impact of machine tool behaviour on machining time and part quality.
Analysis of some of the relevant ISO standards (230-1998, 10791-1998) and a
complementary protocol for better understanding HSM technology are presented in
the first part of this paper. These ISO standards are devoted to the procedures
implemented in order to study the behavior of machine tool.
The paper presents a new stiffness modelling method for multi-chain parallel
robotic manipulators with flexible links and compliant actuating joints. In
contrast to other works, the method involves a FEA-based link stiffness
evaluation and employs a new solution strategy of the kinetostatic equations,
which allows computing the stiffness matrix for singular postures and to take
into account influence of the external forces.
The paper proposes a new calibration method for parallel manipulators that
allows efficient identification of the joint offsets using observations of the
manipulator leg parallelism with respect to the base surface. The method
employs a simple and low-cost measuring system, which evaluates deviation of
the leg location during motions that are assumed to preserve the leg
parallelism for the nominal values of the manipulator parameters. Using the
measured deviations, the developed algorithm estimates the joint offsets that
are treated as the most essential parameters to be identified.
In this paper we describe a new robotic brachytherapy needle-insertion system
that is designed to replace the template used in the manual technique. After a
brief review of existing robotic systems, we describe the requirements that we
based our design upon. A detailed description of the proposed system follows.
Our design is capable of positioning and inclining a needle within the same
workspace as the manual template. To help improve accuracy, the needle can be
rotated about its axis during insertion into the prostate.
A class of analytic planar 3-RPR manipulators is analyzed in this paper.
These manipulators have congruent base and moving platforms and the moving
platform is rotated of 180 deg about an axis in the plane. The forward
kinematics is reduced to the solution of a 3rd-degree polynomial and a
quadratic equation in sequence. The singularities are calculated and plotted in
the joint space. The second-order singularities (cups points), which play an
important role in non-singular change of assembly-mode motions, are also
analyzed.
This paper discusses the utility of using simple stiffness and vibrations
models, based on the Jacobian matrix of a manipulator and only the rigidity of
the actuators, whenever its geometry is optimised. In many works, these
simplified models are used to propose optimal design of robots. However, the
elasticity of the drive system is often negligible in comparison with the
elasticity of the elements, especially in applications where high dynamic
performances are needed.
The aim of this project is to design, study and build an "eel-like robot"
prototype able to swim in three dimensions. The study is based on the analysis
of eel swimming and results in the realization of a prototype with 12
vertebrae, a skin and a head with two fins. To reach these objectives, a
multidisciplinary group of teams and laboratories has been formed in the
framework of two French projects.