Gravitational torque partially accounts for proprioceptive acuity

AbstractUsing the gravitational torque indicator Qb, we derive the distribution of bar strengths for a sample of early-type disk galaxies. The sample is part of the Near-Infrared S0 Survey (NIRS0S), designed to examine the properties of bars, bulges, and disks in galaxies classified as types S0− to Sa. Although the survey is only partly finished, we find that the distribution of bar strengths in S0 galaxies differs from that in spirals by lacking an extended tail to high values of Qb. No S0 in our current sample has Qb > 0.25, while spirals extend to Qb ≈ 0.7. Bars having Qb > 0.25 first appear among S0/a to Sa galaxies.

Download Full-text

Gravitational torque-driven black hole growth and feedback in cosmological simulations

Monthly Notices of the Royal Astronomical Society ◽

10.1093/mnras/stw2565 ◽

2016 ◽

Vol 464 (3) ◽

pp. 2840-2853 ◽

Cited By ~ 56

Author(s):

Daniel Anglés-Alcázar ◽

Romeel Davé ◽

Claude-André Faucher-Giguère ◽

Feryal Özel ◽

Philip F. Hopkins

Keyword(s):

Black Hole ◽

Cosmological Simulations ◽

Gravitational Torque ◽

Black Hole Growth ◽

Hole Growth

Download Full-text

Gravitational Torque Impulse on a Stabilized Satellite

ARS Journal ◽

10.2514/8.5840 ◽

1961 ◽

Vol 31 (11) ◽

pp. 1506-1509 ◽

Cited By ~ 8

Author(s):

PAUL F. HULTQUIST

Keyword(s):

Gravitational Torque

Download Full-text

Design of a Gravity-Balanced Assistive Device for Sit-to-Stand Tasks

Volume 2: 28th Biennial Mechanisms and Robotics Conference, Parts A and B ◽

10.1115/detc2004-57434 ◽

2004 ◽

Author(s):

Abbas Fattah ◽

Sunil K. Agrawal ◽

John Fitzgibbons

Keyword(s):

Center Of Mass ◽

The Elderly ◽

Joint Torque ◽

Assistive Device ◽

Inverse Dynamic ◽

Joint Torques ◽

Gravitational Torque ◽

Total Potential ◽

Cord Injury ◽

Standing Up

The joint torques in hip, knee and ankle are computed using inverse dynamic model during standing up for a paraplegic patient. The joint torque comprises the dynamical torque due to the inertia forces, and a passive torque due to the muscles and gravitational torque. It has been observed that the contribution to the joint torques by the gravitational torque is dominant. On the basis of this result, a gravity balanced assistive device is proposed for the elderly and impaired people such as spinal cord injury and paraplegic patients. This passive device uses a hybrid method to identify the center of mass of the system using auxiliary parallelograms first. Next appropriate springs are connected to the device to vanish the total potential energy of the system due to the gravity during standing up. A prototype with the underlying principles is currently being fabricated at the University of Delaware.

Download Full-text

Simultaneous gravity and gripping force compensation mechanism for lightweight hand-arm robot with low-reduction reducer

Robotica ◽

10.1017/s0263574718001479 ◽

2019 ◽

Vol 37 (6) ◽

pp. 1090-1103 ◽

Cited By ~ 1

Author(s):

Mitsunori Uemura ◽

Yuki Mitabe ◽

Sadao Kawamura

Keyword(s):

Gear Ratio ◽

Robot Hand ◽

Compensation Mechanism ◽

Robot Arm ◽

Unstructured Environments ◽

Gravitational Torque ◽

Gripping Force ◽

Force Compensation

SummaryIn this paper, we propose a novel mechanism to compensate for gravity and the gripping force in a hand-arm robot. This mechanism compensates for the gravitational torque produced by an object gripped by the hand-arm robot. The gripping force required for the robot hand to prevent the object from dropping is also simultaneously compensated for. This mechanism requires only one actuator placed on the shoulder part of the robot. Therefore, this mechanism can reduce the torque requirement of joint actuators and lower the weight of the robot. The gear ratio of the reduction gears in each robot joint can then also be reduced. These advantages are critical for future robots that perform tasks in unstructured environments and collaborate with humans. We carried out experiments with a 6-DoF robot arm having a 1-DoF gripper to demonstrate the effectiveness of the proposed mechanism.

Download Full-text