5,970 research outputs found
A Framework to Illustrate Kinematic Behavior of Mechanisms by Haptic Feedback
The kinematic properties of mechanisms are well known by the researchers and
teachers. The theory based on the study of Jacobian matrices allows us to
explain, for example, the singular configuration. However, in many cases, the
physical sense of such properties is difficult to explain to students. The aim
of this article is to use haptic feedback to render to the user the
signification of different kinematic indices. The framework uses a Phantom Omni
and a serial and parallel mechanism with two degrees of freedom. The
end-effector of both mechanisms can be moved either by classical mouse, or
Phantom Omni with or without feedback
Dynamic Active Constraints for Surgical Robots using Vector Field Inequalities
Robotic assistance allows surgeons to perform dexterous and tremor-free
procedures, but robotic aid is still underrepresented in procedures with
constrained workspaces, such as deep brain neurosurgery and endonasal surgery.
In these procedures, surgeons have restricted vision to areas near the surgical
tooltips, which increases the risk of unexpected collisions between the shafts
of the instruments and their surroundings. In this work, our
vector-field-inequalities method is extended to provide dynamic
active-constraints to any number of robots and moving objects sharing the same
workspace. The method is evaluated with experiments and simulations in which
robot tools have to avoid collisions autonomously and in real-time, in a
constrained endonasal surgical environment. Simulations show that with our
method the combined trajectory error of two robotic systems is optimal.
Experiments using a real robotic system show that the method can autonomously
prevent collisions between the moving robots themselves and between the robots
and the environment. Moreover, the framework is also successfully verified
under teleoperation with tool-tissue interactions.Comment: Accepted on T-RO 2019, 19 Page
Generation of dynamic motion for anthropomorphic systems under prioritized equality and inequality constraints
In this paper, we propose a solution to compute full-dynamic motions for a humanoid robot, accounting for various kinds of constraints such as dynamic balance or joint limits. As a first step, we propose a unification of task-based control schemes, in inverse kinematics or inverse dynamics. Based on this unification, we generalize the cascade of quadratic programs that were developed for inverse kinematics only. Then, we apply the solution to generate, in simulation, wholebody motions for a humanoid robot in unilateral contact with the ground, while ensuring the dynamic balance on a non horizontal surface
Towards Assistive Feeding with a General-Purpose Mobile Manipulator
General-purpose mobile manipulators have the potential to serve as a
versatile form of assistive technology. However, their complexity creates
challenges, including the risk of being too difficult to use. We present a
proof-of-concept robotic system for assistive feeding that consists of a Willow
Garage PR2, a high-level web-based interface, and specialized autonomous
behaviors for scooping and feeding yogurt. As a step towards use by people with
disabilities, we evaluated our system with 5 able-bodied participants. All 5
successfully ate yogurt using the system and reported high rates of success for
the system's autonomous behaviors. Also, Henry Evans, a person with severe
quadriplegia, operated the system remotely to feed an able-bodied person. In
general, people who operated the system reported that it was easy to use,
including Henry. The feeding system also incorporates corrective actions
designed to be triggered either autonomously or by the user. In an offline
evaluation using data collected with the feeding system, a new version of our
multimodal anomaly detection system outperformed prior versions.Comment: This short 4-page paper was accepted and presented as a poster on
May. 16, 2016 in ICRA 2016 workshop on 'Human-Robot Interfaces for Enhanced
Physical Interactions' organized by Arash Ajoudani, Barkan Ugurlu, Panagiotis
Artemiadis, Jun Morimoto. It was peer reviewed by one reviewe
Optimal Image-Based Guidance of Mobile Manipulators using Direct Visual Servoing
This paper presents a direct image-based controller to perform the guidance of a mobile manipulator using image-based control. An eye-in-hand camera is employed to perform the guidance of a mobile differential platform with a seven degrees-of-freedom robot arm. The presented approach is based on an optimal control framework and it is employed to control mobile manipulators during the tracking of image trajectories taking into account robot dynamics. The direct approach allows us to take both the manipulator and base dynamics into account. The proposed image-based controllers consider the optimization of the motor signals sent to the mobile manipulator during the tracking of image trajectories by minimizing the control force and torque. As the results show, the proposed direct visual servoing system uses the eye-in-hand camera images for concurrently controlling both the base platform and robot arm. The use of the optimal framework allows us to derive different visual controllers with different dynamical behaviors during the tracking of image trajectories.This research was supported by the Valencia Regional Government through project GV/2018/050
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