20 research outputs found
Robust self-propulsion in sand using simply controlled vibrating cubes
Much of the Earth and many surfaces of extraterrestrial bodies are composed
of in-cohesive particle matter. Locomoting on granular terrain is challenging
for common robotic devices, either wheeled or legged. In this work, we discover
a robust alternative locomotion mechanism on granular media -- generating
movement via self-vibration. To demonstrate the effectiveness of this
locomotion mechanism, we develop a cube-shaped robot with an embedded vibratory
motor and conduct systematic experiments on diverse granular terrains of
various particle properties. We investigate how locomotion changes as a
function of vibration frequency/intensity on granular terrains. Compared to
hard surfaces, we find such a vibratory locomotion mechanism enables the robot
to move faster, and more stable on granular surfaces, facilitated by the
interaction between the body and surrounding granules. The simplicity in
structural design and controls of this robotic system indicates that vibratory
locomotion can be a valuable alternative way to produce robust locomotion on
granular terrains. We further demonstrate that such cube-shape robots can be
used as modular units for morphologically structured vibratory robots with
capabilities of maneuverable forward and turning motions, showing potential
practical scenarios for robotic systems
Integrating Reconfigurable Foot Design, Multi-modal Contact Sensing, and Terrain Classification for Bipedal Locomotion
The ability of bipedal robots to adapt to diverse and unstructured terrain
conditions is crucial for their deployment in real-world environments. To this
end, we present a novel, bio-inspired robot foot design with stabilizing tarsal
segments and a multifarious sensor suite involving acoustic, capacitive,
tactile, temperature, and acceleration sensors. A real-time signal processing
and terrain classification system is developed and evaluated. The sensed
terrain information is used to control actuated segments of the foot, leading
to improved ground contact and stability. The proposed framework highlights the
potential of the sensor-integrated adaptive foot for intelligent and adaptive
locomotion.Comment: 7 pages, 6 figure
Simulation of compound anchor intrusion in dry sand by a hybrid FEM+SPH method
Preprint submitted to Computers and GeotechnicsThe intrusion of deformable compound anchors in dry sand is simulated by coupling the Finite Element Method (FEM) with Smoothed Particle Hydrodynamics (SPH). This novel approach can calculate granular flows at lower computational cost than SPH alone. The SPH and FEM domains interact through reaction forces calculated from balance equations and are assigned the same soil constitutive model (Drucker-Prager) and the same constitutive parameters (measured or calibrated). Experimental force-displacement curves are reproduced for penetration depths of 8 mm or more (respectively, 20 mm or more) for spike-shaped (respectively, fan-shaped) anchors with 1 to 6 blades. As the number of blades increases, simulations reveal that the granular flow under the anchor deviates from the vertical and that the horizontal granular flow transitions from orthoradial to radial. We interpret the strain field distribution as the result of soil arching, i.e., the transfer of stress from a yielding mass of soil onto adjoining stationary soil masses. Arching is fully active when the radial distance between blade end points is less than a critical length. In that case, the normal stress that acts on the compound anchor at a given depth reaches the normal stress that acts on a disk-shaped anchor of same radius. A single-blade anchor produces soil deformation and failure similar to Prandtl’s foundation sliding model. Multiblade anchors produce a complex failure mechanism that combines sliding and arching
Internet of Things in Sustainable Energy Systems
Our planet has abundant renewable and conventional energy resources but technological capability and capacity gaps coupled with water-energy needs limit the benefits of these resources to citizens. Through IoT technology solutions and state-of-the-art IoT sensing and communications approaches, the sustainable energy-related research and innovation can bring a revolution in this area. Moreover, by the leveraging current infrastructure, including renewable energy technologies, microgrids, and power-to-gas (P2G) hydrogen systems, the Internet of Things in sustainable energy systems can address challenges in energy security to the community, with a minimal trade-off to environment and culture. In this chapter, the IoT in sustainable energy systems approaches, methodologies, scenarios, and tools is presented with a detailed discussion of different sensing and communications techniques. This IoT approach in energy systems is envisioned to enhance the bidirectional interchange of network services in grid by using Internet of Things in grid that will result in enhanced system resilience, reliable data flow, and connectivity optimization. Moreover, the sustainable energy IoT research challenges and innovation opportunities are also discussed to address the complex energy needs of our community and promote a strong energy sector economy
Mortality and pulmonary complications in patients undergoing surgery with perioperative SARS-CoV-2 infection: an international cohort study
Background: The impact of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) on postoperative recovery needs to be understood to inform clinical decision making during and after the COVID-19 pandemic. This study reports 30-day mortality and pulmonary complication rates in patients with perioperative SARS-CoV-2 infection. Methods: This international, multicentre, cohort study at 235 hospitals in 24 countries included all patients undergoing surgery who had SARS-CoV-2 infection confirmed within 7 days before or 30 days after surgery. The primary outcome measure was 30-day postoperative mortality and was assessed in all enrolled patients. The main secondary outcome measure was pulmonary complications, defined as pneumonia, acute respiratory distress syndrome, or unexpected postoperative ventilation. Findings: This analysis includes 1128 patients who had surgery between Jan 1 and March 31, 2020, of whom 835 (74·0%) had emergency surgery and 280 (24·8%) had elective surgery. SARS-CoV-2 infection was confirmed preoperatively in 294 (26·1%) patients. 30-day mortality was 23·8% (268 of 1128). Pulmonary complications occurred in 577 (51·2%) of 1128 patients; 30-day mortality in these patients was 38·0% (219 of 577), accounting for 81·7% (219 of 268) of all deaths. In adjusted analyses, 30-day mortality was associated with male sex (odds ratio 1·75 [95% CI 1·28–2·40], p\textless0·0001), age 70 years or older versus younger than 70 years (2·30 [1·65–3·22], p\textless0·0001), American Society of Anesthesiologists grades 3–5 versus grades 1–2 (2·35 [1·57–3·53], p\textless0·0001), malignant versus benign or obstetric diagnosis (1·55 [1·01–2·39], p=0·046), emergency versus elective surgery (1·67 [1·06–2·63], p=0·026), and major versus minor surgery (1·52 [1·01–2·31], p=0·047). Interpretation: Postoperative pulmonary complications occur in half of patients with perioperative SARS-CoV-2 infection and are associated with high mortality. Thresholds for surgery during the COVID-19 pandemic should be higher than during normal practice, particularly in men aged 70 years and older. Consideration should be given for postponing non-urgent procedures and promoting non-operative treatment to delay or avoid the need for surgery. Funding: National Institute for Health Research (NIHR), Association of Coloproctology of Great Britain and Ireland, Bowel and Cancer Research, Bowel Disease Research Foundation, Association of Upper Gastrointestinal Surgeons, British Association of Surgical Oncology, British Gynaecological Cancer Society, European Society of Coloproctology, NIHR Academy, Sarcoma UK, Vascular Society for Great Britain and Ireland, and Yorkshire Cancer Research
Alpha-Band Activity in Parietofrontal Cortex Predicts Future Availability of Vibrotactile Feedback in Prosthesis Use
Source code
and
preprocessed electroencephalographic
and kinematics data.Prosthesis disuse and abandonment is an ongoing issue in upper-limb amputation. In addition
to lost structural and motor function,
amputation also results in decreased task-specific sensory
information. One proposed remedy is augmenting somatosensory information using
vibrotactile feedback to provide tactile feedback of grasping objects. While the role of frontal
and parietal areas in motor tasks is well established, the neural and kinematic effects of this
augmented vibrotactile feedback remain in question. In this study, we sought to understand the
neurobehavioral effects of providing augmented feedback during a reach-grasp
-transport task.
Ten persons with sound limbs performed a motor task while wearing a prosthesis simulator
with and without vibrotactile feedback. We hypothesized that providing vibrotactile feedback
during prosthesis use would increase activity in frontal and parie
tal areas and improve grasp-related behavior. Results show that anticipation of upcoming vibrotactile feedback may be
encoded in motor and parietal areas during the reach-to-grasp phase of the task. While grasp
aperture is unaffected by vibrotactile feedback, the availability of vibrotactile feedback does
lead to a reduction in velocity during object transport. These results help shed light on how
engineered feedback is utilized by prostheses users and provide methodologies for further
assessment in advanced prosthetics research.National Institutes of Health T32HD05518
Alpha-Band Activity in Left Motor Cortex Predicts Future Availability of Vibrotactile Feedback in Prosthesis Use
Source code and
preprocessed electroencephalographic
and kinematics dataProsthesis disuse and abandonment is an ongoing issue in upper-limb amputation. In addition
to lost structural and motor function, amputation also results in decreased task-specific sensory
information. One proposed remedy is augmenting somatosensory information using
vibrotactile feedback to provide tactile feedback of grasping objects. While the role of frontal
and parietal areas in motor tasks is well established, the neural and kinematic effects of this
augmented vibrotactile feedback remain in question. In this study, we sought to understand the
neurobehavioral effects of providing augmented feedback during a reach-grasp-transport task.
Ten persons with sound limbs performed a motor task while wearing a prosthesis simulator
with or without vibrotactile feedback. For comparison, a second group of ten people performed
the same task with their hands using a pair of tongs. We hypothesized that providing
vibrotactile feedback during prosthesis use would increase activity in frontal and parietal areas
and improve grasp-related behavior. We additionally hypothesized that, relative to tongs users,
prosthesis users would show impaired grasp-related behavior and increased frontal and parietal
activity. Results show that anticipation of upcoming vibrotactile feedback may be encoded in
motor areas during the reach-to-grasp phase of the task. Vibrotactile feedback leads to a
reduction in velocity during object transport. Relative to tongs users, prosthesis users showed
reduced parietofrontal activity, as well as lower velocities and increased grasp peak aperture.
These results help shed light on how engineered feedback is utilized by prostheses users and
provide methodologies for further assessment in advanced prosthetics research.National Institutes of Health T32HD05518