scholarly journals Effect of Mass-Center Position of Spinal Segment on Dynamic Performances of Quadruped Bounding with a Flexible-Articulated Spine

2020 ◽  
Vol 10 (4) ◽  
pp. 1491
Author(s):  
Shun Zeng ◽  
Yuegang Tan ◽  
Zhang Li ◽  
Ping Wu ◽  
Tianliang Li ◽  
...  
Keyword(s):  
Hip Joint ◽  
Stride Length ◽  
Mass Center ◽  
Spinal Segment ◽  
High Speeds ◽  
Geometric Center ◽  
Center Position ◽  
Dynamic Performances ◽  
Fast Movement ◽  
All Speeds

Driven by the layout design of devices arranged on the spine of quadruped robot which has a symmetry spine with a flexible joint, we explore the effect of mass-center position of spinal segment (MCPSS) on dynamic performances of quadruped bounding. A simplified model is introduced with MCPSS set as an independent parameter. Periodically quadruped bounding motions are generated to calculate different dynamic performances related to different MCPSS at the low, medium, and high horizontal speeds, respectively. The results indicate MCPSS corresponding to the optimal or suboptimal dynamic performances mainly gather at two positions: the hip joint and the geometric center of spinal segment. MCPSS near the hip joint leads to the largest stride period, stride length, and spinal oscillation-margin at all speeds. The smallest duty factor can also be obtained at the medium and high speeds. These improved inherent characteristics offer advantages in leg-orientation control and fast movement effectively. MCPSS near the geometric center of spinal segment brings the best self-stability, the smallest mass-center vertical fluctuation, and the smallest maximum foot-end force at all speeds, which should greatly enhance resistances to vertical jitters and reduce torque-demands of joint-drivers. This study should give useful suggestions to robot designs in reality.

Detection of Vehicle Tripped and Untripped Rollovers by a Novel Index With Mass-Center-Position Estimations

2017 ◽  
Author(s):  
Fengchen Wang ◽  
Yan Chen
Keyword(s):  
Load Transfer ◽  
Center Of Mass ◽  
Roll Motion ◽  
Mass Center ◽  
Motion Models ◽  
Center Position ◽  
Before And After ◽  
Vehicle Rollover ◽  
Lift Off ◽  
Rollover Index

This paper presents a novel mass-center-position (MCP) metric for vehicle rollover propensity detection. MCP is first determined by estimating the positions of the center of mass of one sprung mass and two unsprung masses with two switchable roll motion models, before and after tire lift-off. The roll motion information without saturation can then be provided through MCP continuously. Moreover, to detect completed rollover statues for both tripped and untripped rollovers, the criteria are derived from d’Alembert principle and moment balance conditions based on MCP. In addition to tire lift-off, three new rollover statues, rollover threshold, rollover occurrence, and vehicle jumping into air can be all identified by the proposed criteria. Compared with an existing rollover index, lateral load transfer ratio, the fishhook maneuver simulation results in CarSim® for an E-class SUV show that MCP metric can successfully predict the vehicle impending rollover without saturation for untripped rollovers. Tripped rollovers caused by a triangle road bump are also successfully detected in the simulation. Thus, MCP metric can be successfully applied for rollover propensity prediction.

The effect of training on the swimming muscles of the goldfish (Carassius auratus)

1978 ◽  
Vol 74 (1) ◽  
pp. 115-122 ◽  
Author(s):  
W. Davison ◽  
G. Goldspink
Keyword(s):  
Carassius Auratus ◽  
Chemical Constituents ◽  
Water Environment ◽  
Muscle Fibres ◽  
Muscle Fibre Size ◽  
Goldfish Carassius Auratus ◽  
High Speeds ◽  
Major Chemical ◽  
All Speeds ◽  
Rates Of Growth

Goldfish (Carassius auratus) were exercised continuously for periods of 28 days at swimming speeds of 1.5, 3.0 and 4.5 body lengths per second and their rates of growth were determined. Changes in muscle fibre size were examined, as were changes which occurred in the concentrations of the major chemical constituents of these cells. These fish, typical of the carp family in that they are found only in still or slowly moving water, did not adapt well to the flowing water environment at any swimming speed. They often grew less than the controls, although consuming much more food. Changes in the composition of the muscle fibres indicated that excess food was not being stored, and also indicated that the major fuel for swimming at all speeds was glycogen. The fish survived well at high speeds and it was suggested that this was due to the ability of the species to metabolize glycogen anaerobically without the production of lactic acid.

scholarly journals The Kinematic and Dynamic Performances of the Loading Mechanism of the Hip Joint Wear Simulator

2011 ◽  
pp. 0595-0596
Author(s):  
Volodymyr Ivanovich Pakhaliuk ◽  
Aleksandr Mykhaylovich Poliakov ◽  
Ivan Borisovich Desyatov ◽  
Mykhaylo Ivanovich Kalinin ◽  
Maxim Gennadyevich Stupko
Keyword(s):  
Hip Joint ◽  
Dynamic Performances ◽  
Wear Simulator

Simple method for correcting hip joint center position in overweight subjects

2020 ◽  
Vol 81 ◽  
pp. 359-360
Author(s):  
P. Swennen ◽  
V.S. Högerle ◽  
D.W.W. Heitzmann ◽  
S.I. Wolf
Keyword(s):  
Hip Joint ◽  
Simple Method ◽  
Center Position ◽  
Joint Center ◽  
Overweight Subjects ◽  
Hip Joint Center

Stride Frequency and Submaximal Treadmill Running Economy in Adults and Children

1990 ◽  
Vol 2 (2) ◽  
pp. 149-155 ◽  
Author(s):  
Viswanath B. Unnithan ◽  
Roger G. Eston
Keyword(s):  
Stride Length ◽  
Oxygen Demand ◽  
The Body ◽  
Running Economy ◽  
Treadmill Running ◽  
Stride Frequency ◽  
Oxygen Cost ◽  
Demand Characteristics ◽  
Adults And Children ◽  
All Speeds

Previous studies have consistently shown that the body mass/relative oxygen cost of submaximal treadmill running is greater in children than in young adults. It has been suggested that the obligatory increased stride frequency in children might be at least partly responsible. This hypothesis was investigated by examining the association between stride frequency and oxygen demand characteristics in 10 aerobically fit prepubescent boys (ages 9-10 yrs) and 10 fit young men (ages 18-25 yrs) while running at fixed submaximal speeds on an electronically driven treadmill. The oxygen demand was higher at all running speeds in the boys’ group. To compensate for a shorter stride length, the boys demonstrated higher stride frequency at all speeds. To determine if the inferior running economy in the boys was partly due to the greater stride frequency, the relative oxygen demand per stride was compared between groups at all speeds. This value was similar in both groups. It is concluded that the apparently greater oxygen demand of running in boys may be due in part to the greater stride frequency required to maintain similar running speeds.

Dynamics of Rolling Element—Bearings Experimental Validation of the DREB and RAPIDREB Computer Programs

1985 ◽  
Vol 107 (1) ◽  
pp. 132-137 ◽  
Author(s):  
P. K. Gupta ◽  
J. F. Dill ◽  
H. E. Bandow
Keyword(s):  
Experimental Data ◽  
Experimental Validation ◽  
Ball Bearing ◽  
Rolling Element Bearings ◽  
Mass Center ◽  
Angular Contact Ball Bearing ◽  
High Speeds ◽  
Rolling Element ◽  
General Motion ◽  
Good Agreement

The general motion of the cage predicted by the computer models in an angular contact ball bearing operating up to two million DN is compared against experimental data. Both the computer predictions and experimental data indicate a certain critical shaft speed at which the cage mass center begins to whirl. The predicted and measured whirl velocities and orbit shapes are in good agreement. The axial and radial velocities of the cage mass center also agree within the tolerance band of the expected experimental error. Due to experimental difficulties the cage angular velocity could not be reliabily measured at high speeds. At low speeds, however, there is a fair agreement between the experimental data and the analytical predictions.

scholarly journals Strategies for increasing gait speed in patients with hip osteoarthritis: their clinical significance and effects on hip loading

2020 ◽  
Author(s):  
Hiroshige Tateuchi ◽  
Haruhiko Akiyama ◽  
Koji Goto ◽  
Kazutaka So ◽  
Yutaka Kuroda ◽  
...  
Keyword(s):  
Physical Function ◽  
Hip Joint ◽  
Gait Speed ◽  
Stride Length ◽  
Three Dimensional ◽  
Joint Space Width ◽  
Hip Osteoarthritis ◽  
Joint Space ◽  
Hip Pain ◽  
Type C

Abstract Background Change in gait speed is required in various situations in daily life, and can be achieved by changing stride length, cadence, or both. Differences in strategies for increasing gait speed may have different effects on the hip joint and on physical function. Our primary purpose was to determine the effects of strategies for increasing gait speed on hip pain and physical function in patients with hip osteoarthritis (OA). The secondary purpose was to examine the effects of strategies for increasing gait speed on the changes in hip loading during gait. Methods Forty-seven patients with secondary hip OA (age 48.3 ± 11.0 years) were included. Gait speed, stride length, cadence, and peak and impulse of the hip joint moment were measured during gait at self-selected normal and fast gait speeds, using a three-dimensional motion analysis system. The patients were classified as types S (increasing mainly stride length), C (increasing mainly cadence), and SC (increasing stride length and cadence) according to whether they used changes in stride length and/or cadence to transition from a normal to a fast gait. Hip pain, physical function, and change in hip moments during gait were compared between the types. Results The distribution of the patients was as follows: types S, 23.4%; C, 48.9%; and SC, 27.7%. Physical function status was higher in types C (P = 0.018) and SC (P = 0.015) than in type S, even after adjustment for age and minimum joint space width. Hip pain was not significantly different between the types. The robustness of those results was confirmed by a sensitivity analysis. The rates of the increases in peak external hip adduction (P = 0.003) and internal rotation moments (P = 0.009) were lower in type C than in type SC. Conclusions Type C tended to suppress the increase in hip joint moments during fast gait. Types C and SC, which included increased cadence, maintained higher physical function levels than type S. Encouraging use of a cadence-increasing strategy may be useful for reducing hip loading and maintaining physical function in patients with hip OA.

scholarly journals Analysis of Visuo Motor Control between Dominant Hand and Non-Dominant Hand for Effective Human-Robot Collaboration

Sensors ◽  
2020 ◽  
Vol 20 (21) ◽  
pp. 6368
Author(s):  
Hanjin Jo ◽  
Woong Choi ◽  
Geonhui Lee ◽  
Wookhyun Park ◽  
Jaehyo Kim
Keyword(s):  
Dimensional Space ◽  
Phase Error ◽  
Three Dimensional ◽  
Frontal Plane ◽  
Dominant Hand ◽  
Precise Control ◽  
Human In The Loop ◽  
High Speeds ◽  
All Speeds ◽  
Human Robot Collaboration

The human-in-the-loop technology requires studies on sensory-motor characteristics of each hand for an effective human–robot collaboration. This study aims to investigate the differences in visuomotor control between the dominant (DH) and non-dominant hands in tracking a target in the three-dimensional space. We compared the circular tracking performances of the hands on the frontal plane of the virtual reality space in terms of radial position error (ΔR), phase error (Δθ), acceleration error (Δa), and dimensionless squared jerk (DSJ) at four different speeds for 30 subjects. ΔR and Δθ significantly differed at relatively high speeds (ΔR: 0.5 Hz; Δθ: 0.5, 0.75 Hz), with maximum values of ≤1% compared to the target trajectory radius. DSJ significantly differed only at low speeds (0.125, 0.25 Hz), whereas Δa significantly differed at all speeds. In summary, the feedback-control mechanism of the DH has a wider range of speed control capability and is efficient according to an energy saving model. The central nervous system (CNS) uses different models for the two hands, which react dissimilarly. Despite the precise control of the DH, both hands exhibited dependences on limb kinematic properties at high speeds (0.75 Hz). Thus, the CNS uses a different strategy according to the model for optimal results.

scholarly journals ASSESSMENT OF IMPACT OF ACTIVATION OF HIP JOINT ABDUCTORS AND EXTERNAL ROTATORS ON GAIT AND RUNNNING PARAMETERS IN HEALTHY PEOPLE - PILOT STUDY

2021 ◽  
pp. 120-126
Author(s):  
Sebastian Wojtowicz ◽  
Anna Daniluk ◽  
Karolina Wiaderna ◽  
Aneta Bugalska ◽  
Anna Hadamus ◽  
...  
Keyword(s):  
Hip Joint ◽  
Stride Length ◽  
Healthy People ◽  
Control Group ◽  
Single Session ◽  
Pressure Force ◽  
Resistance Exercises ◽  
Group 2 ◽  
The Impact ◽  
Group 1

Many physiotherapists and motor preparation coaches recommend including resistance exercises for the hip joint abductors and external rotators in a warm-up. Muscle activation with resistance band exercises is believed to improve positional control of the pelvis and the lower limbs, thus reducing the risk of musculoskeletal injury during rehabilitation or training proper. The aim of this study was to assess the impact of a single session of activation of hip joint abductors and external rotators on gait and running parameters in healthy people. The study involved 54 healthy individuals aged 19-21 years. An experimental group (Group 1) performed a set of 6 resistance exercises with Thera rubber bands, intended to activate the hip joint abductors and external rotators. A control group (Group 2) performed the same set of exercises but without external resistance. A walking and running gait examination was performed on a Zebris FDM treadmill in both groups before and after the exercises. Both variants of exercises produced changes in selected gait parameters (p<0.05). An examination of running gait in Group 1 revealed an increase in step length in the dominant limb (p<0.05) and stride length (p<0.05) and step time in the dominant limb (p<0.05), stride length (p<0.05) and cadence (p<0.05). Heel pressure also decreased in both limbs, and heel pressure force decreased in the non-dominant limb (p<0.05). A running gait examination in Group 2 revealed increased midfoot pressure force in both limbs (p<0.05). Thus, a single session of exercises with resistance banding to activate the hip joint abductors and external rotators exerted an effect on running parameters, which may improve running economy.

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