Wyniki wyszukiwania - Biblioteka Nauki

1

Kinematics of relative body motion and plucker's conoid

100%

Machulda V. , Svilger J.

Modelowanie Inżynierskie

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2006

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tom T. 1, nr 32

345-352

EN

Spatial motion of rigid body is possible to describe by using the screw movement around a certain axis. In this contribution the relative motion between two bodies is analyzed. The kinematic solution is described using kinematic properties of Plűcker’s conoid. Simultaneously the classical kinematic solution of relative motion of two bodies is mentioned. Application of the presented theory to rotors of screw compressor with displacement of rotors position is shown. 1.

2

Realization of optimum breakthrough mode of reversal of roller forming installation

80%

Loveykin V. , Pochka K.

Motrol. Motoryzacja i Energetyka Rolnictwa

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2017

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tom 19

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nr 3

3

Synteza dynamicznie stabilnego chodu dwupodporowego czteronożnego robota kroczącego. Badania symulacyjne (2)

80%

Zielińska T. , Trojnacki M.

Pomiary Automatyka Robotyka

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2007

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tom R. 11, nr 12

5-8

PL

Praca stanowi drugą część publikacji. W pierwszej części przedstawiono metodę wyznaczania sił reakcji podłoża działających na nogi robota. Dla dwupodporowego chodu diagonalnego robota czteronożnego rozwiązano zagadnienie równowagi sił i momentów sprawdzając warunek unikania poślizgu. Podano warunek utrzymania stabilnej postury z uwzględnieniem pracy elementów sprężystych zamocowanych w stopach. W niniejszej pracy pokazano przykład zastosowania tej metody przy uwzględnieniu parametrów i chodu rzeczywistego robota.

EN

This article is the second part of the work on synthesis of dynamically stable gait of a quadruped robot. In the first part the method of determining the forces acting on the robot's leg was presented. The problem of postural equilibrium was solved. The slip avoidance was considered. In this part the example of motion synthesis taking into account the gait properties and parameters of the real robot is presented.

4

Synteza dynamicznie stabilnego chodu dwupodporowego czteronożnego robota kroczącego. Rozważania teoretyczne (1)

80%

Zielińska T. , Trojnacki M.

Pomiary Automatyka Robotyka

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2007

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tom R. 11, nr 11

5-11

PL

W pracy przedstawiono metodę wyznaczania sił reakcji podłoża działających na nogi robota. Dla dwupodporowego chodu diagonalnego robota czteronożnego rozwiązano zagadnienie równowagi sił i momentów, sprawdziwszy warunek unikania poślizgu. Podano warunek utrzymania stabilnej postury z uwzględnieniem pracy elementów sprężystych zamocowanych w stopach.

EN

The method of determining the force distribution acting on the robot's leg is presented. Considering two-legged diagonal gait of the quadruped robot the problem of equilibrating the forces and moments existing in the system was solved. The slippage avoiding condition was considered. The method of robot posture equilibrating taking into account the role of compliant feet was provided.

5

Biomechanical Differences Associated with Two Different Load Carriage Systems and their Relationship to Economy

80%

Lloyd R. , Cooke C.

Human Movement

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2011

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tom 12

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nr 1

65-74

EN

Purpose. To explore relationships between load carriage economy and the kinematics and kinetics of load carriage using both a backpack (BP) and a double pack (DP). Basic procedures. Nine participants walked on a treadmill at gradients of between 27% downhill and 20% uphill, and over a force plate on level ground, at a speed of 3 km.h-1. Expired air was collected throughout the treadmill experiment and all experiments were filmed for subsequent biomechanical analysis. The relative economy of load carriage was expressed in terms of the Extra Load Index (ELI). Main findings. There was a tendency for the double pack system to be associated with better economy than the BP. The double pack system provoked significantly less forward lean than the backpack and the horizontal displacement of the CoM was also smaller for the double pack system and both of these factors were strongly related to economy. There was, however, a greater range of motion of the trunk in the DP condition and this was also associated with improved economy. Conclusions. The results suggest that the DP was associated with smaller perturbations in gait than the BP and that this represents an advantage in terms of economy. In particular freedom of movement of the trunk in the sagittal plane may be an important consideration in the efficiency of load carriage systems.

6

Kinematics of sprint cross-country skiing

80%

Zory R. , Barberis A. , Rouard A. , Schena F.

Acta of Bioengineering and Biomechanics

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2005

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tom Vol. 7, nr 2

88-96

EN

The purpose of our study was to characterise the diagonal stride locomotion during a new short spruit race in cross-country skiing. Thirty male cross-country skiers were sagittaly filmed on an uphill portion of the 1.2-km classic race of the world cup (2004) usmg a digital camera. The mam body joints, skis and poles were digitised frame by frame. Results indicated higher SV and SR for similar SL compared to longer distance races with a sunilar slope. Moreover, significant correlations were observed between SV and SR but not between SV and SL contrary to the other distance races. SL results showed that in spite of the high SR. skiers maintained an effective leg and pole thrusts. The high SR in KO sprint presented a mechanical advantage by minimising the decrease of velocity during the cycle. The importance of SR in the velocity production could be use fill for practitioners to optimise the training program for this type of race. It seemed notable that the skiers had to improve temporal factors while conserving a long SL.

7

Geokinematics in GGOS - different relations and dependences

80%

Pachelski W. , Paśnicka M. , Szafranek K. , Zwirowicz-Rutkowska A.

Artificial Satellites : Journal of Planetary Geodesy

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2011

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tom Vol. 46, No. 1

9--17

EN

The paper presents the preliminary results of the analysis of fundamental dependencies between different geodetic concepts related to the one of the GGOS (Global Geodetic Observation System) pillars called Geometry and Kinematics. These relationships are described using UML (Unified Modelling Language) – one of the graphical notations that can be used for information modelling. Concepts are represented as classes with their names, attributes, and different kinds of links between them. The main purpose of this paper is to introduce the full description of connections between all GGOS components.

8

Kinematyka nowego typu manipulatora równoległego o trzech stopniach swobody

80%

Petko M. , Karpiel G. , Prusak D. , Martowicz A.

Pomiary Automatyka Kontrola

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2004

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tom R. 50, nr 5

25-28

PL

W artykule przedstawiono kinematykę nowego typu manipulatora trójramiennego o trzech stopniach swobody, zbudowanego w Katedrze Robotyki i Dynamiki Maszyn AGH. Wprowadzono analityczne rozwiązanie zadania kinematyki odwrotnej oraz zaproponowano i zbadano metodę szybkiego i dokładnego numerycznego rozwiązywania zadania kinematyki prostej. Podano także sposób przybliżonego rozwiązania analitycznego tego problemu.

EN

In the paper, kinematics of a new type of threelimbs, 3-DOF manipulator, built in the Department of Robotics and Machine Dynamics, AGH is presented. The symbolic, closed form of inverse kinematics is derived. A method of fast and accurate numerical solutions of the forward kinematic problem is proposed and investigated. The way for an approximate, analytic solving of this problem is given.

9

Kinematic Adaptations of Forward and Backward Walking on Land and in Water

80%

Cadenas-Sanchez C. , Arellano R. , Vanrenterghem J. , López-Contreras G.

Journal of Human Kinetics

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2015

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tom 49

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nr 1

15-24

EN

The aim of this study was to compare sagittal plane lower limb kinematics during walking on land and submerged to the hip in water. Eight healthy adults (age 22.1 ± 1.1 years, body height 174.8 ± 7.1 cm, body mass 63.4 ± 6.2 kg) were asked to cover a distance of 10 m at comfortable speed with controlled step frequency, walking forward or backward. Sagittal plane lower limb kinematics were obtained from three dimensional video analysis to compare spatiotemporal gait parameters and joint angles at selected events using two-way repeated measures ANOVA. Key findings were a reduced walking speed, stride length, step length and a support phase in water, and step length asymmetry was higher compared to the land condition (p<0.05). At initial contact, knees and hips were more flexed during walking forward in water, whilst, ankles were more dorsiflexed during walking backward in water. At final stance, knees and ankles were more flexed during forward walking, whilst the hip was more flexed during backward walking. These results show how walking in water differs from walking on land, and provide valuable insights into the development and prescription of rehabilitation and training programs.

10

Breast Support Garments are Ineffective at Reducing Breast Motion During an Aqua Aerobics Jumping Exercise

80%

Mills C. , Ayres B. , Scurr J.

Journal of Human Kinetics

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2015

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tom 46

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nr 1

49-58

EN

The buoyant forces of water during aquatic exercise may provide a form of ‘natural’ breast support and help to minimise breast motion and alleviate exercise induced breast pain. Six larger-breasted females performed standing vertical land and water-based jumps, whilst wearing three breast support conditions. Underwater video cameras recorded the motion of the trunk and right breast. Trunk and relative breast kinematics were calculated as well as exercised induced breast pain scores. Key results showed that the swimsuit and sports bra were able to significantly reduce the superioinferior breast range of motion by 0.04 and 0.05 m, respectively, and peak velocity by 0.23 and 0.33 m/s, respectively, during land-based jumping when compared to the bare-breasted condition, but were ineffective at reducing breast kinematics during water-based jumping. Furthermore, the magnitude of the swimsuit superioinferior breast range of motion during water-based jumping was significantly greater than land-based jumping (0.13 m and 0.06 m), yet there were no significant differences in exercise induced breast pain, thus contradicting previously published relationships between these parameters on land. Furthermore, the addition of an external breast support garment was able to reduce breast kinematics on land but not in water, suggesting the swimsuit and sports bras were ineffective and improvements in swimwear breast support garments may help to reduce excessive breast motion during aqua aerobic jumping exercises.

11

Cable-suspended CPR-D type Parallel Robot

80%

Filipovic M. , Djuric A.

Journal of Theoretical and Applied Mechanics

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2016

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tom Vol. 54 nr 2

645--657

EN

This paper deals with the analysis and synthesis of a newly selected Cable-suspended Parallel Robot configuration, named CPR-D system. The camera carrier workspace has the shape of a parallelepiped. The CPR-D system has a unique Jacobian matrix that maps the relationship between internal and external coordinates. This geometric relationship is a key solution for the definition of the system kinematic and dynamic models. Because of the CPR-D system complexity, the Lagrange principle of virtual work has been adapted. Two significant Examples have been used for the CPR-D system analysis and validation.

12

Kinematic regulation of time and frequency domain components of accelerations measured at the tibia during heel-toe running

80%

Sinclair J. , Taylor P. J. , Hobbs S. J.

Human Movement

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2014

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tom 15

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nr 1

51-55

EN

Purpose. The transmission of tibial accelerations through the musculoskeletal system may contribute to the aetiology of injuries. Therefore, determining the mechanisms that regulate impact accelerations may have potential clinical significance. This study aimed to determine the influence of lower extremity kinematics on the regulation of both time and frequency domain characteristics of tibial accelerations during running. Methods. Forty participants ran at 4.0 m · s-1 ± 5%. Three-dimensional joint kinematics from the hip, knee and ankle were measured using an eight-camera motion analysis system operating at 250 Hz. Regression analyses treating time and frequency domain tibial acceleration parameters as criterion variables were used to identify lower extremity parameters associated with the passive regulation of impact accelerations. Results. The overall regression model yielded an adj. R2 = 0.13, p 0.01. Knee flexion velocity at footstrike was identified as a significant regulator of tibial accelerations in the time domain. No kinematic variables were identified as significantly related to the frequency domain properties of the signal. Conclusions. The findings of the current investigation suggest that sagittal plane knee flexion velocity at footstrike can regulate the magnitude of impact loading linked to the development of chronic injuries.

13

Sex Differences in Tibiocalcaneal Kinematics

80%

Sinclair J. , Taylor P. J.

Human Movement

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2014

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tom 15

|

nr 2

105-109

EN

Purpose. Female runners typically suffer more from chronic running injuries than age-matched males, although the exact biome-chanical mechanisms behind the increased susceptibility of female runners are unknown. This study aimed to compare sex differences in tibiocalcaneal kinematics during the stance phase of running. Methods. Twenty male and twenty female participants ran at 4.0 m · s–1. Tibiocalcaneal kinematics were measured using an eight-camera motion analysis system and compared using independent samples t tests. Results. Peak eversion and tibial internal rotation angles were shown to be significantly greater in female runners. Conclusions. based on these observations, it was determined that female runners may be at increased risk from chronic injury development in relation to excessive tibiocalcaneal motions in the coronal and transverse planes.

14

Design of a path following controller for an underactuated AUV

80%

Subudhi B. , Atta D.

Archives of Control Sciences

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2009

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tom Vol. 19, no. 4

437-450

EN

This paper describes a tracking control strategy for an underactuated autonomous underwater vehicle (AUV) on a two dimensional plane (ℜ²). Based on a smooth, inertial, 2D reference trajectory curve, the proposed algorithm uses vehicle dynamics to generate the reference orientation and body-fixed velocities. Following these, required error dynamics are developed. Error dynamics are then stabilized using inverse dynamics control strategy, forcing the tracking error to an arbitrarily small neighborhood of zero. Circular path, as a constant velocity reference trajectory, has been chosen for simulation studies. Simulation results are included to demonstrate the tracking performance of the controller.

15

Recursive multipath effect mitigation in kinematic satellite observations

80%

Szpunar R.

Reports on Geodesy

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2008

|

tom z. 1/84

73-77

EN

The satellite kinematic observations are currently used in many precise point positioning applications. Unfortunately the multipath is the limiting error source for high precision measurcment. This is important problem in the real time GPS monitoring applications. The paper presents, recursive multipath effect mitigation in kinematic satellite observations, for one-day GPS observation series in geodetic control networks.

16

Inter-Examiner, Within-Session and Between-Session Repeatability of Kinematic Gait Parameters Among Adult Subjects

80%

Leszczewska J. , Czaprowski D. , Pawłowska P. , Oponowicz A.

Human Movement

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2012

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tom 13

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nr 4

337-343

EN

Purpose. This research aimed to assess the repeatability of results obtained when analysing gait by means of a system designed for objective gait analysis in a single laboratory setting by a single examiner within-session and between-sessions. Methods. For the purpose of this research, the BTS Smart-D movement analysis system, produced by Capture Motion System of Italy, was used. Four healthy adults were examined. The subjects took part in three gait analysis testing sessions, with each session separated by a two-day break. During each session, two sets of measurements were taken for each subject. Statistical analysis was performed with StatSoft’s Statistica 7.1 software. Results. Within each session, all examined temporal and spatial parameters were found to be repeatable. Only in hip and knee joint rotation was repeatability not confirmed within session. Between the sessions, repeatability was confirmed in pelvic rotation, abduction/adduction of the knee joint and for all foot kinematic parameters. Conclusions. Conducting gait analysis by one researcher does not guarantee obtaining repeatable results for all measured kinematic parameters, either within one session or between sessions; caution ought to be exercised when interpreting results. Among the studied parameters, hip and knee joint rotation provided the most difficulty in obtaining repeatable results. For this reason, diagnostic and therapeutic decisions based on such data require the utmost consideration.

17

Searching for critical conditions during lifeboat launching – simulations

80%

Dymarski C. , Dymarski P. , Kniat A.

Polish Maritime Research

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2017

|

tom S 1

53--58

EN

The article describes numerical simulations of the process of lifeboat launching at the ship’s side. The research aimed at finding the values of ship motion parameters which appear to be most dangerous for people in the lowered lifeboat due to the generated accelerations. The simplified model of ship hull motion adopted at this research stage bases on a superposition of harmonic motions with given amplitudes and periods in six degrees of freedom. The range of the amplitude of motion for each degree of freedom corresponds approximately to that of possible motion of the PANAMAX type ship on the Baltic sea. In total, 120 960 cases of ship hull motion were examined.

18

On the material and spatial description of rigid fields

80%

Rudnicki M.

Journal of Theoretical and Applied Mechanics

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2005

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tom Vol. 43 nr 4

825--840

EN

Rigid kinematics is re-examined applying the material, spatial and mixed description without use of any coordinate system. Some tensor representations for the displacement gradient, velocity gradient, and acceleration gradient are obtained. Special cases of rotation about fixed as well as nearly fixed axis are distinguished. Assumption of small rotation is also taken into account. Relative motion of a particle is briefly described.

PL

Rozważono kinematykę ciała sztywnego w opisie materialnym, przestrzennym i mieszanym bez wprowadzania układu współrzędnych. Przedstawiono reprezentacje tensorowe gradientów pól przemieszczenia, prędkości i przyspieszenia. Wyodrębniono przypadki szczególne obrotu wokół stałej oraz prawie stałej osi. Zbadano ruch przy założeniu małego obrotu. Naszkicowano zagadnienie ruchu względnego cząstki.

19

New concept of a rocker engine - kinematic analysis

80%

Szymkowiak M. , Szwaja S.

Journal of KONES

|

2012

|

tom Vol. 19, No. 3

443-449

EN

The paper presents concept and design of a four-stroke 4-cylinder internal combustion engine consisted of a single connecting rod to a crankshaft and four additional rods joining pistons with a rocker. The rocker is a specific element in the engine construction that makes this engine different from the typical reciprocating internal combustion piston engine. Furthermore, kinematical analysis of this piston - rocker - crankshaft mechanism was conducted. As concluded from the analysis, this mechanism implemented to the engine, provides several advantages with respect to both dynamic and thermodynamic related issues. First of all, a profile of the piston motion can be easily changed with change in the mechanism geometry e.g. major dimensions of connecting rods, the rocker etc. Thus, the piston motion profile can be asymmetrical with slow motion to and relatively fast distancing from the TDC. This feature can be useful in reducing thermal losses to an engine cooling system. Additionally, the mechanism characterizes itself with low transverse force from the piston, which acts on a cylinder liner. As a result, it significantly reduces frictional losses and should increase the overall efficiency of the engine. Among disadvantages, higher inertial forces are the most important problem. As analyzed, the rocker is the main component that contributes to increase in inertial forces by approximately three to four times. On the other hand, total inertia forces, due to specific kinematical chain of the mechanism, can be remarkably reduced in case the mechanism is correctly optimized.

20

Influence of Different Hip Joint Centre Locations on Hip and Knee Joint Kinetics and Kinematics During the Squat

80%

Sinclair J. , Atkins S. , Vincent H.

Journal of Human Kinetics

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2014

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tom 44

|

nr 1

5-17

EN

Identification of the hip joint centre (HJC) is important in the biomechanical examination of human movement. However, there is yet to be any published information regarding the influence of different HJC locations on hip and knee joint kinetics during functional tasks. This study aimed to examine the influence of four different HJC techniques on 3- D hip and knee joint kinetics/kinematics during the squat. Hip and knee joint kinetics/kinematics of the squat were obtained from fifteen male participants using an eight camera motion capture system. The 3-D kinetics/kinematics of the squat were quantified using four hip joint centre estimation techniques. Repeated measures ANOVAs were used to compare the discrete parameters as a function of each HJC location. The results show that significant differences in joint angles and moment parameters were evident at both the hip and knee joint in the coronal and transverse planes. These observations indicate that when calculating non-sagittal joint kinetics/kinematics during the squat, researchers should carefully consider their HJC method as it may significantly affect the interpretation of their data.