An Analysis on Sliding of Biped Robots

2010 ◽  
Author(s):  
C. H. Liu ◽  
Chi-Hwa Wu ◽  
Yin-Tien Wang
Keyword(s):  
Stress Distribution ◽  
Point Contact ◽  
Ground Reaction Forces ◽  
Line Contact ◽  
Normal Stresses ◽  
Biped Robots ◽  
Tangential Stresses ◽  
Reaction Forces ◽  
Instantaneous Center ◽  
Contact Stress Distribution

In this paper we study the instability of biped robots that is a combination of both sliding and tipping over. Specifically, when robot falling occurs, the ground reaction forces and moments on a foot may determine if sliding also happens. We deal with the situation that tipping over is impending, and treat the following three possible types of contact stress distribution on the foot: point contact, line contact, and area contact. In line and area contact regions we assume that normal stresses are Hertzian, then tangential stresses may be determined by utilizing theory of instantaneous center of zero velocity in planar kinematics. From these normal and tangential stresses we may determine force combinations that cause sliding.

scholarly journals Plantar Tactile Feedback for Biped Balance and Locomotion on Unknown Terrain

2020 ◽  
Vol 17 (01) ◽  
pp. 1950036 ◽  
Author(s):  
J. Rogelio Guadarrama Olvera ◽  
Emmanuel Dean Leon ◽  
Florian Bergner ◽  
Gordon Cheng
Keyword(s):  
Center Of Pressure ◽  
Tactile Feedback ◽  
Ground Reaction Forces ◽  
Biped Robots ◽  
Sensing System ◽  
Sensing Technology ◽  
Precise Shape ◽  
Reaction Forces ◽  
Resultant Forces ◽  
Robot Skin

This work introduces a new sensing system for biped robots based on plantar robot skin, which provides not only the resultant forces applied on the ankles but a precise shape of the pressure distribution in the sole together with other extra sensing modalities (temperature, pre-touch and acceleration). The information provided by the plantar robot skin can be used to compute the center of pressure and the ground reaction forces. This information also enables the online construction of the supporting polygon and its preemptive shape before foot landing using the proximity sensors in the robot skin. Two experiments were designed to show the advantages of this new sensing technology for improving balance and walking controllers for biped robots over unknown terrain.

scholarly journals Contact mechanics in fretting fatigue

2012 ◽  
Vol 3 (3) ◽  
pp. 199-206
Author(s):  
J. De Pauw ◽  
P. De Baets ◽  
W. De Waele ◽  
R. Hojjati
Keyword(s):  
Stress Distribution ◽  
Contact Mechanics ◽  
Material Properties ◽  
Present Theory ◽  
Fretting Fatigue ◽  
Line Contact ◽  
Stress Distributions ◽  
Tangential Stresses ◽  
The Coefficient Of Friction ◽  
Applied Forces

This paper studies the contact mechanics in a line contact during fretting fatigue conditions. Inliterature one can find numerical and analytical solutions of normal and tangential stresses for a variety ofloading cases. However, a unified solution valid for all loading cases during fretting fatigue conditions is notavailable. We present in this paper a strategy to combine existing contact mechanics theories into a unifiedcalculation procedure. Therefore, the relevant contact mechanics theories for an idealized cylinder-on-flatcontact are selected and bundled. Two clear flowcharts group the existing theories, which results in aunified strategy that can easily be implemented in a programming language. A Matlab script wasprogrammed and calculates the normal and tangential stress distribution based on the applied forces, thegeometry of the contact, the coefficient of friction and the material properties. The present theory can beused to automate the calculation of the stress distributions, or as validation of new numerical techniques.The script is modular and can be extended to calculate the lifetime of a component, by adding lifetimecriteria.

Normal and shear stress measurements on a strip footing

1979 ◽  
Vol 16 (1) ◽  
pp. 177-189 ◽  
Author(s):  
G. E. Bauer ◽  
D. H. Shields ◽  
J. D. Scott ◽  
S. O. Nwabuokei
Keyword(s):  
Shear Stress ◽  
Stress Distribution ◽  
Contact Stress ◽  
Earth Pressure ◽  
Strip Footing ◽  
Normal Stresses ◽  
Test Results ◽  
Stress Measurements ◽  
Contact Stress Distribution ◽  
Made In

This paper deals with the choice, calibration, and use of earth pressure cells in the measurement of the contact stress distribution across a strip footing. The footing was 30 cm wide, rough, and rigid; the measurements were made in a laboratory with the footing bearing on compact to dense, air dry, uniform, crushed quartz sand.Typical test results are compared with the theoretical distributions of both shear and normal stresses that have been proposed by various authors.

scholarly journals Running ground reaction forces across footwear conditions are predicted from the motion of two body mass components

2019 ◽  
Vol 126 (5) ◽  
pp. 1315-1325 ◽  
Author(s):  
Andrew B. Udofa ◽  
Kenneth P. Clark ◽  
Laurence J. Ryan ◽  
Peter G. Weyand
Keyword(s):  
Ground Reaction Force ◽  
Lower Limb ◽  
Reaction Force ◽  
Ground Reaction Forces ◽  
Vertical Ground Reaction Force ◽  
Time Patterns ◽  
Foot Strike ◽  
Reaction Forces ◽  
Vertical Ground ◽  
Force Time

Although running shoes alter foot-ground reaction forces, particularly during impact, how they do so is incompletely understood. Here, we hypothesized that footwear effects on running ground reaction force-time patterns can be accurately predicted from the motion of two components of the body’s mass (mb): the contacting lower-limb (m1 = 0.08mb) and the remainder (m2 = 0.92mb). Simultaneous motion and vertical ground reaction force-time data were acquired at 1,000 Hz from eight uninstructed subjects running on a force-instrumented treadmill at 4.0 and 7.0 m/s under four footwear conditions: barefoot, minimal sole, thin sole, and thick sole. Vertical ground reaction force-time patterns were generated from the two-mass model using body mass and footfall-specific measures of contact time, aerial time, and lower-limb impact deceleration. Model force-time patterns generated using the empirical inputs acquired for each footfall matched the measured patterns closely across the four footwear conditions at both protocol speeds ( r2 = 0.96 ± 0.004; root mean squared error  = 0.17 ± 0.01 body-weight units; n = 275 total footfalls). Foot landing angles (θF) were inversely related to footwear thickness; more positive or plantar-flexed landing angles coincided with longer-impact durations and force-time patterns lacking distinct rising-edge force peaks. Our results support three conclusions: 1) running ground reaction force-time patterns across footwear conditions can be accurately predicted using our two-mass, two-impulse model, 2) impact forces, regardless of foot strike mechanics, can be accurately quantified from lower-limb motion and a fixed anatomical mass (0.08mb), and 3) runners maintain similar loading rates (ΔFvertical/Δtime) across footwear conditions by altering foot strike angle to regulate the duration of impact. NEW & NOTEWORTHY Here, we validate a two-mass, two-impulse model of running vertical ground reaction forces across four footwear thickness conditions (barefoot, minimal, thin, thick). Our model allows the impact portion of the impulse to be extracted from measured total ground reaction force-time patterns using motion data from the ankle. The gait adjustments observed across footwear conditions revealed that runners maintained similar loading rates across footwear conditions by altering foot strike angles to regulate the duration of impact.

scholarly journals Ground Reaction Forces of Dressage Horses Performing the Piaffe

Animals ◽  
2021 ◽  
Vol 11 (2) ◽  
pp. 436 ◽  
Author(s):  
Hilary Mary Clayton ◽  
Sarah Jane Hobbs
Keyword(s):  
Coefficient Of Variation ◽  
Three Dimensional ◽  
Individual Variability ◽  
The Other ◽  
Ground Reaction Forces ◽  
High Coefficient ◽  
Reaction Forces

The piaffe is an artificial, diagonally coordinated movement performed in the highest levels of dressage competition. The ground reaction forces (GRFs) of horses performing the piaffe do not appear to have been reported. Therefore, the objective of this study was to describe three-dimensional GRFs in ridden dressage horses performing the piaffe. In-ground force plates were used to capture fore and hindlimb GRF data from seven well-trained dressage horses. Peak vertical GRF was significantly higher in forelimbs than in the hindlimbs (7.39 ± 0.99 N/kg vs. 6.41 ± 0.64 N/kg; p < 0.001) with vertical impulse showing a trend toward higher forelimb values. Peak longitudinal forces were small with no difference in the magnitude of braking or propulsive forces between fore and hindlimbs. Peak transverse forces were similar in magnitude to longitudinal forces and were mostly directed medially in the hindlimbs. Both the intra- and inter-individual variability of longitudinal and transverse GRFs were high (coefficient of variation 25–68%). Compared with the other diagonal gaits of dressage horses, the vertical GRF somewhat shifted toward the hindlimbs. The high step-to-step variability of the horizontal GRF components is thought to reflect the challenge of balancing on one diagonal pair of limbs with no forward momentum.

scholarly journals Peripheral arterial disease affects ground reaction forces during walking

2007 ◽  
Vol 46 (3) ◽  
pp. 491-499 ◽  
Author(s):  
Melissa M. Scott-Pandorf ◽  
Nicholas Stergiou ◽  
Jason M. Johanning ◽  
Leon Robinson ◽  
Thomas G. Lynch ◽  
...  
Keyword(s):  
Peripheral Arterial Disease ◽  
Arterial Disease ◽  
Ground Reaction Forces ◽  
Reaction Forces ◽  
Peripheral Arterial

scholarly journals Ground Reaction Forces and Kinematics of Ski Jump Landing Using Wearable Sensors

Sensors ◽  
2019 ◽  
Vol 19 (9) ◽  
pp. 2011 ◽  
Author(s):  
Bessone ◽  
Petrat ◽  
Schwirtz
Keyword(s):  
Wearable Sensors ◽  
Reaction Force ◽  
Ground Reaction Forces ◽  
Inertial Motion ◽  
Jump Landing ◽  
The Past ◽  
Landing Biomechanics ◽  
Reaction Forces ◽  
The Hill ◽  
Kinematics And Kinetics

In the past, technological issues limited research focused on ski jump landing. Today, thanks to the development of wearable sensors, it is possible to analyze the biomechanics of athletes without interfering with their movements. The aims of this study were twofold. Firstly, the quantification of the kinetic magnitude during landing is performed using wireless force insoles while 22 athletes jumped during summer training on the hill. In the second part, the insoles were combined with inertial motion units (IMUs) to determine the possible correlation between kinematics and kinetics during landing. The maximal normal ground reaction force (GRFmax) ranged between 1.1 and 5.3 body weight per foot independently when landing using the telemark or parallel leg technique. The GRFmax and impulse were correlated with flying time (p < 0.001). The hip flexions/extensions and the knee and hip rotations of the telemark front leg correlated with GRFmax (r = 0.689, p = 0.040; r = −0.670, p = 0.048; r = 0.820, p = 0.007; respectively). The force insoles and their combination with IMUs resulted in promising setups to analyze landing biomechanics and to provide in-field feedback to the athletes, being quick to place and light, without limiting movement.

Anterior-posterior ground reaction forces across a range of running speeds in unilateral transfemoral amputees

2020 ◽  
pp. 1-12
Author(s):  
Hiroyuki Sakata ◽  
Satoru Hashizume ◽  
Ryo Amma ◽  
Genki Hisano ◽  
Hiroto Murata ◽  
...  
Keyword(s):  
Ground Reaction Forces ◽  
Reaction Forces ◽  
Transfemoral Amputees ◽  
Anterior Posterior
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