1,721,296 research outputs found
A Smooth Approximation of Mobile Platform Displacement for Mobile Haptic Interfaces
No full textOne of most interesting aspects in haptic research
deals with the extension of application workspace, thus
allowing haptic simulation within large virtual environments. Several devices have been realized that allow
this kind of interaction, in particular our interest focuses on mobile haptic interfaces, realized by combining
classic grounded haptic devices with mobile platforms.
While grounded haptic interfaces feature fast sampling
rate and finest quantization, mobile haptic interfaces are
multirate devices where the displacement sampling of
mobile platform may affect the quality of haptic rendering. In this paper we introduce a simple smoothing algorithm that allows to approximate a slow-rate and roughquantized sampled signal representing mobile robot displacement with a fast rate and smooth signal. Evaluation experiments confirmed that the proposed algorithm
allows to preserve a good quality of haptic rendering
Supervisory switching control in robotic manipulation
No full textA switching controller for a class of robotic manipulators with grasping capabilities is presented. The aim is to control the motion of the grasped object along a desired trajectory while complying with contact force constraints
Using vibrations for haptic feedback discrimination in teleoperation
No full textThe European project ACTIVE aims at developing
an integrated redundant robotic platform for neurosurgery.
During tele-operation, the surgeon perceives on a haptic device
the interaction of the tool with the brain tissue by means of
a force/torque sensor mounted on the slave. Moreover, active
constraints prevent damage to eloquent areas and assist the
surgeon by constraining and directing his motions. Having two
sources of haptic feedback, and only one haptic device through
which it can be displayed makes it difficult to distinguish between
the two sources. In this extended abstract, we formalize the
problem and propose a solution based on vibratory feedback.
The platform that we’ve set up in order to take our findings from
virtual reality to teleoperation is described, as well as the current
work we’re performing in order to cover not only forbidden
region active constraints, but also guidance forces
A geometric procedure for robust decoupling control of contact forces in robotic manipulation
Full text linksummary:This paper deals with the problem of controlling contact forces in robotic manipulators with general kinematics. The main focus is on control of grasping contact forces exerted on the manipulated object. A visco-elastic model for contacts is adopted. The robustness of the decoupling controller with respect to the uncertainties affecting system parameters is investigated. Sufficient conditions for the invariance of decoupling action under perturbations on the contact stiffness and damping parameters are provided. These conditions are meaningful for several classes of manipulation systems with general kinematics
Consistent task specification for manipulation systems with general kinematics
No full textAlthough most of the literature on manipulation systems deals with systems with as many degrees of freedom as the dimension of their task space, or even with more (redundant manipulators), kinematically defective manipulation systems are often encountered in robotics, in particular when dealing with simple industry-oriented grippers, or when the whole surface of the manipulator limbs is exploited to constrain the manipulated object, as in "whole-arm" manipulation. Kinematically defective systems differ from nondefective and redundant manipulation systems in many ways, some of which have been addressed in the literature. In this paper, we focus on one of the central problems of manipulation, i.e., controlling the manipulator in order to track a desired object trajectory, while guaranteeing that contact forces are controlled so as to comply with contact constraints (friction bounds, etc.) at every instant. We attack this problem by an unified approach that is appropriate for manipulation systems with general kinematics. When dealing with kinematically defective systems, it is not possible to assign arbitrary trajectories of object motions and contact forces. To understand what restrictions position and force reference trajectories should exhibit in order to be feasible by a given system, is the central issue of this work
Sensory subtraction via cutaneous feedback: a novel technique to improve the transparency of robotic surgery
No full textIn this paper we present a novel technique to force feedback in robot-assisted surgery. It consists of substituting haptic force, composed by kinesthetic and cutaneous components, with cutaneous stimuli only. The force generated can be thus thought as a subtraction between the complete haptic interaction, cutaneous and kinesthetic, and the kinesthetic part of it. For this reason, we refer to this approach as sensory
subtraction and not sensory substitution. Sensory subtraction, first introduced in [1], aims at improving the performance of conventional force feedback techniques in teleoperation while
guaranteeing the same stability properties. In this work we recall the idea of sensory subtraction in teleoperation, together with its evaluation in two paradigmatic surgical teleoperation scenarios
A standard form for the dynamics of general manipulation systems
No full textConsiders the structural properties of the dynamics of robotic manipulation systems of a rather general class, including multiple cooperating, possibly whole-arm limbs, interacting with a manipulated object by means of contacts. A geometric approach to the analysis of the linearized dynamics of such systems is presented, which provides much insight in some of their intrinsic characteristics in the light of classical system-theoretic concepts such as controllability, observability, and canonical forms
Controllability of whole-arm manipulation
No full textWhole-arm manipulators systems (WAMs), i.e. robotic devices that use not only their extremities but rather any of their links to manipulate objects, are robust and have a wide range of applicability. The analysis and control of such systems pose problems not common to traditional robotics. In this paper, we consider a peculiar loss of a controllability property that deep affects operation of WAM
- …
