18 research outputs found
Open-loop position control in collaborative, modular Variable-Stiffness-Link (VSL) robots
— Collaborative robots (cobots) open up new avenues
in the fields of industrial robotics and physical Human-Robot
Interaction (pHRI) as they are suitable to work in close approximation and in collaboration with humans. The integration
and control of variable stiffness elements allow inherently safe
interaction. Apart from notable work on Variable Stiffness
Actuators, the concept of Variable-Stiffness-Link (VSL) manipulators promises safety improvements in cases of unintentional
physical collisions. However, position control of these type of
robotic manipulators is challenging for critical task-oriented
motions (e.g., pick and place). Hence, the study of open-loop
position control for VSL robots is crucial to achieve high
levels of safety, accuracy and hardware cost-efficiency in pHRI
applications. In this paper, we propose a hybrid, learning based
kinematic modelling approach to improve the performance
of traditional open-loop position controllers for a modular,
collaborative VSL robot. We show that our approach improves
the performance of traditional open-loop position controllers
for robots with VSL and compensates for position errors, in
particular, for lower stiffness values inside the links: Using
our upgraded and modular robot, two experiments have been
carried out to evaluate the behaviour of the robot during taskoriented motions. Results show that traditional model-based
kinematics are not able to accurately control the position
of the end-effector: the position error increases with higher
loads and lower pressures inside the VSLs. On the other
hand, we demonstrate that, using our approach, the VSL robot
can outperform the position control compared to a robotic
manipulator with 3D printed rigid links
Grasping Angle Estimation of Human Forearm with Underactuated Grippers Using Proprioceptive Feedback
In this paper, a method for the estimation of the angle of grasping of a human forearm, when grasped by a robot with an underactuated gripper, using proprioceptive information only, is presented.
Knowing the angle around the forearm’s axis (i.e. roll angle) is key for the safe manipulation of the human limb and biomedical sensor placement among others. The adaptive gripper has two independent underactuated fingers with two phalanges and a single actuator each. The final joint position of the gripper provides information related to the shape of the grasped object without the need for external contact or force sensors.
Regression methods to estimate the roll angle of the grasping have been trained with forearm grasping information from different humans at each angular position. The results show that it is possible to accurately estimate the rolling angle of the human arm, for trained and unknown people.Universidad de Málaga. Campus de Excelencia Internacional Andalucía Tec
Natural History of MYH7-Related Dilated Cardiomyopathy
BACKGROUND: Variants in myosin heavy chain 7 (MYH7) are responsible for disease in 1% to 5% of patients with dilated cardiomyopathy (DCM); however, the clinical characteristics and natural history of MYH7-related DCM are poorly described. OBJECTIVE: We sought to determine the phenotype and prognosis of MYH7-related DCM. We also evaluated the influence of variant location on phenotypic expression. METHODS: We studied clinical data from 147 individuals with DCM-causing MYH7 variants (47.6% female; 35.6 ± 19.2 years) recruited from 29 international centers. RESULTS: At initial evaluation, 106 (72.1%) patients had DCM (left ventricular ejection fraction: 34.5% ± 11.7%). Median follow-up was 4.5 years (IQR: 1.7-8.0 years), and 23.7% of carriers who were initially phenotype-negative developed DCM. Phenotypic expression by 40 and 60 years was 46% and 88%, respectively, with 18 patients (16%) first diagnosed at <18 years of age. Thirty-six percent of patients with DCM met imaging criteria for LV noncompaction. During follow-up, 28% showed left ventricular reverse remodeling. Incidence of adverse cardiac events among patients with DCM at 5 years was 11.6%, with 5 (4.6%) deaths caused by end-stage heart failure (ESHF) and 5 patients (4.6%) requiring heart transplantation. The major ventricular arrhythmia rate was low (1.0% and 2.1% at 5 years in patients with DCM and in those with LVEF of ≤35%, respectively). ESHF and major ventricular arrhythmia were significantly lower compared with LMNA-related DCM and similar to DCM caused by TTN truncating variants. CONCLUSIONS: MYH7-related DCM is characterized by early age of onset, high phenotypic expression, low left ventricular reverse remodeling, and frequent progression to ESHF. Heart failure complications predominate over ventricular arrhythmias, which are rare
Age-related changes in the soluble and the membrane-bound Tyr-aminopeptidase activities in several areas of the male and female rat brain
A Hybrid Learning and Optimization Framework to Achieve Physically Interactive Tasks With Mobile Manipulators
This letter proposes a hybrid learning and optimization framework for mobile manipulators for complex and physically interactive tasks. The framework exploits an admittance-type physical interface to obtain intuitive and simplified human demonstrations and Gaussian Mixture Model (GMM)/Gaussian Mixture Regression (GMR) to encode and generate the learned task requirements in terms of position, velocity, and force profiles. Next, using the desired trajectories and force profiles generated by GMM/GMR, the impedance parameters of a Cartesian impedance controller are optimized online through a Quadratic Program augmented with an energy tank to ensure the passivity of the controlled system. Two experiments are conducted to validate the framework, comparing our method with two approaches with constant stiffness (high and low). The results showed that the proposed method outperforms the other two cases in terms of trajectory tracking and generated interaction forces, even in the presence of disturbances such as unexpected end-effector collisions
A Personalizable Controller for the Walking Assistive omNi-Directional Exo-Robot (WANDER)
Preserving and encouraging mobility in the elderly and adults with chronic
conditions is of paramount importance. However, existing walking aids are
either inadequate to provide sufficient support to users' stability or too
bulky and poorly maneuverable to be used outside hospital environments. In
addition, they all lack adaptability to individual requirements. To address
these challenges, this paper introduces WANDER, a novel Walking Assistive
omNi-Directional Exo-Robot. It consists of an omnidirectional platform and a
robust aluminum structure mounted on top of it, which provides partial body
weight support. A comfortable and minimally restrictive coupling interface
embedded with a force/torque sensor allows to detect users' intentions, which
are translated into command velocities by means of a variable admittance
controller. An optimization technique based on users' preferences, i.e.,
Preference-Based Optimization (PBO) guides the choice of the admittance
parameters (i.e., virtual mass and damping) to better fit subject-specific
needs and characteristics. Experiments with twelve healthy subjects exhibited a
significant decrease in energy consumption and jerk when using WANDER with PBO
parameters as well as improved user performance and comfort. The great
interpersonal variability in the optimized parameters highlights the importance
of personalized control settings when walking with an assistive device, aiming
to enhance users' comfort and mobility while ensuring reliable physical
support
Project Summary: TRUST-ROB, Towards Resilient UGV and UAV Manipulator Teams For Robotic Search and Rescue Tasks
The paper was presented at the Project Summary sessions.This Project Summary paper reviews the main contributions and lessons learned from the TRUST-ROB project: “Towards Resilient
UGV and UAV Manipulator Teams for Robotic Search and Rescue Tasks”, which has been developed between 2019 and 2022 with funding from the Spanish Government (RTI2018-093421-B-I00).This TRUST-ROB project has been funded by the Ministerio de Ciencia, Innovación y Universidades, Gobierno de España RTI2018-093421-B-I00. The presentation of this Project Summary paper has been partially funded by Universidad de Málaga, Andalucía Tech