6,129 research outputs found
Folding Assembly by Means of Dual-Arm Robotic Manipulation
In this paper, we consider folding assembly as an assembly primitive suitable
for dual-arm robotic assembly, that can be integrated in a higher level
assembly strategy. The system composed by two pieces in contact is modelled as
an articulated object, connected by a prismatic-revolute joint. Different
grasping scenarios were considered in order to model the system, and a simple
controller based on feedback linearisation is proposed, using force torque
measurements to compute the contact point kinematics. The folding assembly
controller has been experimentally tested with two sample parts, in order to
showcase folding assembly as a viable assembly primitive.Comment: 7 pages, accepted for ICRA 201
Control strategy for cooperating disparate manipulators
To manipulate large payloads typical of space construction, the concept of a small arm mounted on the end of a large arm is introduced. The main purposes of such a configuration are to increase the structural stiffness of the robot by bracing against or locking to a stationary frame, and to maintain a firm position constraint between the robot's base and workpieces by grasping them. Possible topologies for a combination of disparate large and small arms are discussed, and kinematics, dynamics, controls, and coordination of the two arms, especially when they brace at the tip of the small arm, are developed. The feasibility and improvement in performance are verified, not only with analytical work and simulation results but also with experiments on the existing arrangement Robotic Arm Large and Flexible and Small Articulated Manipulator
Autonomous Sweet Pepper Harvesting for Protected Cropping Systems
In this letter, we present a new robotic harvester (Harvey) that can
autonomously harvest sweet pepper in protected cropping environments. Our
approach combines effective vision algorithms with a novel end-effector design
to enable successful harvesting of sweet peppers. Initial field trials in
protected cropping environments, with two cultivar, demonstrate the efficacy of
this approach achieving a 46% success rate for unmodified crop, and 58% for
modified crop. Furthermore, for the more favourable cultivar we were also able
to detach 90% of sweet peppers, indicating that improvements in the grasping
success rate would result in greatly improved harvesting performance
Dynamic Modeling and Simulation of a Rotating Single Link Flexible Robotic Manipulator Subject to Quick Stops
Single link robotic manipulators are extensively used in industry and research operations. The main design requirement of such manipulators is to minimize link dynamic deflection and its active end vibrations, and obtain high position accuracy during its high speed motion. To achieve these requirements, accurate mathematical modeling and simulation of the initial design, to increase system stability and precision and to obtain very small amplitudes of vibration, should be considered. In this paper the modeling of such robotic arm with a rigid guide and a flexible extensible link subject to quick stops after each complete revolution is considered and its dynamical behavior analyzed. The extensible link which rotates with constant angular velocity has one end constrained to a predefined trajectory. The constrained trajectory allows trajectory control and obstacle avoidance for the active end of the robotic arm. The dynamic evolution of the system is investigated and the flexural response of the flexible link analyzed under the combined effect of clearance and flexibility.
Deep Visual Foresight for Planning Robot Motion
A key challenge in scaling up robot learning to many skills and environments
is removing the need for human supervision, so that robots can collect their
own data and improve their own performance without being limited by the cost of
requesting human feedback. Model-based reinforcement learning holds the promise
of enabling an agent to learn to predict the effects of its actions, which
could provide flexible predictive models for a wide range of tasks and
environments, without detailed human supervision. We develop a method for
combining deep action-conditioned video prediction models with model-predictive
control that uses entirely unlabeled training data. Our approach does not
require a calibrated camera, an instrumented training set-up, nor precise
sensing and actuation. Our results show that our method enables a real robot to
perform nonprehensile manipulation -- pushing objects -- and can handle novel
objects not seen during training.Comment: ICRA 2017. Supplementary video:
https://sites.google.com/site/robotforesight
Design of an Anthropomorphic, Compliant, and Lightweight Dual Arm for Aerial Manipulation
This paper presents an anthropomorphic, compliant and lightweight dual arm manipulator designed and developed for aerial manipulation applications with multi-rotor platforms. Each arm provides four degrees of freedom in a human-like kinematic configuration for end effector positioning: shoulder pitch, roll and yaw, and elbow pitch. The dual arm, weighting 1.3 kg in total, employs smart servo actuators and a customized and carefully designed aluminum frame structure manufactured by laser cut. The proposed
design reduces the manufacturing cost as no computer numerical control machined part is used. Mechanical joint compliance is provided in all the joints, introducing a compact spring-lever transmission mechanism between the servo shaft and the links, integrating a potentiometer for measuring the deflection of the joints.
The servo actuators are partially or fully isolated against impacts and overloads thanks to the ange bearings attached to the frame structure that support the rotation of the links and the deflection of the joints. This simple mechanism increases the robustness of the arms and safety in the physical interactions between the aerial
robot and the environment. The developed manipulator has been validated through different experiments in fixed base test-bench and in outdoor flight tests.Unión Europea H2020-ICT-2014- 644271Ministerio de Economía y Competitividad DPI2015-71524-RMinisterio de Economía y Competitividad DPI2017-89790-
An Open-Source 7-Axis, Robotic Platform to Enable Dexterous Procedures within CT Scanners
This paper describes the design, manufacture, and performance of a highly
dexterous, low-profile, 7 Degree-of-Freedom (DOF) robotic arm for CT-guided
percutaneous needle biopsy. Direct CT guidance allows physicians to localize
tumours quickly; however, needle insertion is still performed by hand. This
system is mounted to a fully active gantry superior to the patient's head and
teleoperated by a radiologist. Unlike other similar robots, this robot's fully
serial-link approach uses a unique combination of belt and cable drives for
high-transparency and minimal-backlash, allowing for an expansive working area
and numerous approach angles to targets all while maintaining a small in-bore
cross-section of less than . Simulations verified the system's
expansive collision free work-space and ability to hit targets across the
entire chest, as required for lung cancer biopsy. Targeting error is on average
on a teleoperated accuracy task, illustrating the system's sufficient
accuracy to perform biopsy procedures. The system is designed for lung biopsies
due to the large working volume that is required for reaching peripheral lung
lesions, though, with its large working volume and small in-bore
cross-sectional area, the robotic system is effectively a general-purpose
CT-compatible manipulation device for percutaneous procedures. Finally, with
the considerable development time undertaken in designing a precise and
flexible-use system and with the desire to reduce the burden of other
researchers in developing algorithms for image-guided surgery, this system
provides open-access, and to the best of our knowledge, is the first
open-hardware image-guided biopsy robot of its kind.Comment: 8 pages, 9 figures, final submission to IROS 201
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