130,879 research outputs found
Robot Grasp Control
No full textGrasp control refers to the art of controlling the motion of an object by constraining its dynamics through contacts with a hand. The process of controlling the grasp is not limited to robotic hands only but also applies to human hands (Johansson and Edin 1991) and to all other mechanisms using contact constraints to control the motion of the manipulated object (Brost and Goldberg 1996).
A crucial role in the control of grasping is played by contact constraints. All the interactions between the robotic hand and the grasped object occur at the contacts whose understanding is paramount (Salisbury and Roth 1983). The unilateral nature of contact interaction in grasping makes the control problems much more challenging than cooperative manipulation where multiple arms hold the object rigidly allowing bilateral force transmission at each contact point (Chiacchio et al. 1991).
The importance of unilateral contact constraints in grasping led a large part of the literature to focus..
Range estimation from a moving camera: an Immersion and Invariance approach
No full textThe paper proposes an original solution to the range identification problem for perspective dynamical systems. The depth of a static point observed by a pinhole camera undergoing a predefined 3-D motion, is estimated from its 2-D projection on the image plane. The proposed nonlinear observer relies on the Immersion and Invariance (I&I) methodology and offers several advantages over the existing range estimators. The paper also provides an analytical study of nonlinear observability performed with the Extended Output Jacobian. Extensive simulation experiments illustrate the theory and show the effectiveness of the proposed design
Robotics in Second Life
No full textVirtual worlds are quickly growing; both in interactivity and realism, users can experience through their avatars, and the number of actual users is continuously growing as well. Among the virtual worlds, Second Life (SL) is perhaps one of the most famous. This article presents a project whose aim is to use SL as a means to spread robotics culture as well as to investigate possible paradigms of social interaction in heterogeneous communities of robots and humans. As a first step, a point of presence has been established in SL through the development of a building to represent and host the activities of the IEEE Robotics and Automation Society (RAS). In addition, simplified models and behaviors of some robots have been reproduced and used for demonstrations both within and around the building itself
Beyond the Pandemic: The Role of Haptics in Defining the New Normal
No full textDiscusses the role haptics technology plays in the COVID-19 pandemic. Haptics permeates our lives. During the COVID-19 pandemic, where social distancing continues to affect the way we interact with other people and the environment, haptic technology can play a pivotal role in bringing touch back into our everyday lives. Haptic technology is shifting from something useful to improve virtual and remote interactions into something vital for the physical and particularly mental wellbeing of the human species
Image-based Visual Servoing with Central Catadioptric Camera
No full textThis paper presents an image-based visual servoing strategy for the autonomous navigation of a mobile holonomic
robot from a current toward a desired pose, specified only through a current and a desired image acquired by the
on-board central catadioptric camera. This kind of vision sensor combines lenses and mirrors to enlarge the field
of view. The proposed visual servoing does not need any metrical information about the 3-D viewed scene and
is mainly based on a novel geometrical property, the auto-epipolar condition, which occurs when two catadioptric
views (current and desired) undergo a pure translation. This condition can be detected in real-time in the image
domain observing when a set of so-called disparity-conics have a common intersection. The auto-epipolar condition
and the pixel distances between current and target image features are used to design the image-based control law.
Lyapunov-based stability analysis and simulation results demonstrate the parametric robustness of the proposed
method. Experimental results are presented to show the applicability of our visual servoing in a real context
Image-based Visual Servoing for Nonholonomic Mobile Robots with Central Catadioptric Camera
No full textWe present an image-based visual servoing strategy for nonholonomic mobile robot equipped with a central catadioptric camera. This kind of vision sensor combines lens and mirrors to enlarge the field of view. The proposed approach, which exploits the epipolar geometry defined by the current and the desired camera views, does not need any knowledge of the 3-D scene geometry. The control scheme is divided in two steps. In the first one, the epipoles are used together with an approximate input-output linearizing feedback to align the robot with the goal. Feature points are then used in the second translation step to reach the desired configuration. Global asymptotic convergence is proven. Simulation and experimental results show the effectiveness of the proposed control scheme
A new approach to the cheap LQ regulator exploiting the geometric properties of the Hamiltonian system
No full textThe cheap LQ regulator is reinterpreted as an output nulling problem which is a basic problem of the geometric control theory. In fact, solving the LQ regulator problem is equivalent to keep the output of the related Hamiltonian system identically zero. The solution lies on a controlled invariant subspace whose dimension is characterized in terms of the minimal conditioned invariant of the original system, and the optimal feedback gain is computed as the friend matrix of the resolving subspace. This study yields a new computational framework for the cheap LQ regulator, relying only on the very basic and simple tools of the geometric approach, namely the algorithms for controlled and conditioned invariant subspaces and invariant zeros
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
Squaring Down LTI Systems: A Geometric Approach
No full textIn this paper, the problem of reducing a given LTI system into a left or right invertible one is addressed and solved with the standard tools
of the geometric control theory. First, it will be shown how an LTI system can be turned into a left invertible system, thus preserving key
system properties like stabilizability, phase minimality, right invertibility, relative degree and infinite zero structure. Moreover, the additional
invariant zeros introduced in the left invertible system thus obtained can be arbitrarily assigned in the complex plane. By duality, the scheme
of a right inverter will be derived straightforwardly. Moreover, the squaring down problem will be addressed. In fact, when the left and right
reduction procedures are applied together, a system with an unequal number of inputs and outputs is turned into a square and invertible system.
Furthermore, as an example it will be shown how these techniques may be employed to weaken the standard assumption of left invertibility
of the plant in many optimization problems
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