9,674 research outputs found
Planning and Real Time Control of a Minimally Invasive Robotic Surgery System
This paper introduces the planning and control software of a teleoperating robotic system for minimally invasive surgery. It addresses the problem of how to organize a complex system with 41 degrees of freedom including robot setup planning, force feedback control and nullspace handling with three robotic arms. The planning software is separated into sequentially executed planning and registration procedures. An optimal setup is first planned in virtual reality and then adapted to variations in the operating room. The real time control system is composed of hierarchical layers. The design is flexible and expandable without losing performance. Structure, functionality and implementation of planning and control are described. The robotic system provides the surgeon with an intuitive hand-eye-coordination and force feedback in teleoperation for both hands
Human Like Adaptation of Force and Impedance in Stable and Unstable Tasks
Abstract—This paper presents a novel human-like learning con-troller to interact with unknown environments. Strictly derived from the minimization of instability, motion error, and effort, the controller compensates for the disturbance in the environment in interaction tasks by adapting feedforward force and impedance. In contrast with conventional learning controllers, the new controller can deal with unstable situations that are typical of tool use and gradually acquire a desired stability margin. Simulations show that this controller is a good model of human motor adaptation. Robotic implementations further demonstrate its capabilities to optimally adapt interaction with dynamic environments and humans in joint torque controlled robots and variable impedance actuators, with-out requiring interaction force sensing. Index Terms—Feedforward force, human motor control, impedance, robotic control. I
Impedence Control for Variable Stiffness Mechanisms with Nonlinear Joint Coupling
The current discussion on physical human robot
interaction and the related safety aspects, but also the interest
of neuro-scientists to validate their hypotheses on human motor
skills with bio-mimetic robots, led to a recent revival of tendondriven
robots. In this paper, the modeling of tendon-driven
elastic systems with nonlinear couplings is recapitulated. A
control law is developed that takes the desired joint position
and stiffness as input. Therefore, desired motor positions are
determined that are commanded to an impedance controller.
We give a physical interpretation of the controller. More importantly,
a static decoupling of the joint motion and the stiffness
variation is given. The combination of active (controller) and
passive (mechanical) stiffness is investigated. The controller
stiffness is designed according to the desired overall stiffness.
A damping design of the impedance controller is included in
these considerations. The controller performance is evaluated
in simulation
Design method for an anthropomorphic hand able to gesture and grasp
This paper presents a numerical method to conceive and design the kinematic
model of an anthropomorphic robotic hand used for gesturing and grasping. In
literature, there are few numerical methods for the finger placement of
human-inspired robotic hands. In particular, there are no numerical methods,
for the thumb placement, that aim to improve the hand dexterity and grasping
capabilities by keeping the hand design close to the human one. While existing
models are usually the result of successive parameter adjustments, the proposed
method determines the fingers placements by mean of empirical tests. Moreover,
a surgery test and the workspace analysis of the whole hand are used to find
the best thumb position and orientation according to the hand kinematics and
structure. The result is validated through simulation where it is checked that
the hand looks well balanced and that it meets our constraints and needs. The
presented method provides a numerical tool which allows the easy computation of
finger and thumb geometries and base placements for a human-like dexterous
robotic hand.Comment: IEEE International Conference on Robotics and Automation, May 2015,
Seattle, United States. IEEE, 2015, Proceeding IEEE International Conference
on Robotics and Automatio
Collision Detection and Reaction: A Contribution to Safe Physical Human-Robot Interaction
In the framework of physical Human-Robot Interaction
(pHRI), methodologies and experimental tests are
presented for the problem of detecting and reacting to collisions
between a robot manipulator and a human being. Using a
lightweight robot that was especially designed for interactive
and cooperative tasks, we show how reactive control strategies
can significantly contribute to ensuring safety to the human
during physical interaction. Several collision tests were carried
out, illustrating the feasibility and effectiveness of the proposed
approach. While a subjective “safety” feeling is experienced by
users when being able to naturally stop the robot in autonomous
motion, a quantitative analysis of different reaction strategies
was lacking. In order to compare these strategies on an objective
basis, a mechanical verification platform has been built. The
proposed collision detection and reactions methods prove to
work very reliably and are effective in reducing contact forces
far below any level which is dangerous to humans. Evaluations
of impacts between robot and human arm or chest up to a
maximum robot velocity of 2.7 m/s are presented
Practice of law in the provisioning of accessibility facilities for person with disabilities in Malaysia
Malaysia’s significant changes can be seen clearly through the improvement of social welfare of the disabled and people with disabilities. Although the governments has carried out various policies and provide facilities as well as provision for the disabled but there are still many obstacles encountered by people with disabilities, especially the legal and the accessibility of facilities and services. Therefore, this paper attempts to discuss the practice of law relating of legal procedure particularly for disabled users which affects the movement of these people from one destination to another. This paper discusses the practice of law adopted in the preparation of facilities for disabled people to help them make movement independently. The study was conducted by secondary data to the Malaysia legal and policies for disabled person by comparing with United Kingdom (UK). Malaysia has come out with a strong legal framework for disabled person through People with Disabilities Act 2008 (Act 685). There are several areas in the act that still can be improved to support disabled person
GPS Multipath Detection in the Frequency Domain
Multipath is among the major sources of errors in precise positioning using
GPS and continues to be extensively studied. Two Fast Fourier Transform
(FFT)-based detectors are presented in this paper as GPS multipath detection
techniques. The detectors are formulated as binary hypothesis tests under the
assumption that the multipath exists for a sufficient time frame that allows
its detection based on the quadrature arm of the coherent Early-minus-Late
discriminator (Q EmL) for a scalar tracking loop (STL) or on the quadrature (Q
EmL) and/or in-phase arm (I EmL) for a vector tracking loop (VTL), using an
observation window of N samples. Performance analysis of the suggested
detectors is done on multipath signal data acquired from the multipath
environment simulator developed by the German Aerospace Centre (DLR) as well as
on multipath data from real GPS signals. Application of the detection tests to
correlator outputs of scalar and vector tracking loops shows that they may be
used to exclude multipath contaminated satellites from the navigation solution.
These detection techniques can be extended to other Global Navigation Satellite
Systems (GNSS) such as GLONASS, Galileo and Beidou.Comment: 2016 European Navigation Conference (ENC 2016), May 2016, Helsinki,
Finland. Proceedings of the 2016 European Navigation Conference (ENC 2016
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