Initial Posture Research Articles

여유 구동 병렬기구를 이용한 마스크-패널 얼라인 로붓 시스템

In this paper, a mask-panel alignment robot system is considered for IT industry applications. Two kinds of solutions are suggested which are required in constructing a control system for the alignment robot with actuation redundancy. First, the kinematic solution for the 4PPR parallel positioning mechanism is formulated for an arbitrary initial posture, which relates the mask-panel misalignment in the task space and the desired actuator displacements in the joint space. Secondly, in order to increase the stiffness of the control motion and also to avoid the mechanical lock which may happen due to the redundant actuation, a new synchronous control method is proposed which has the merit of coordinating joint control motions while not losing individual joint control performance. In addition, the engineering process to develop a visual alignment robot system is described with the results of experimental setup and GUI software. Finally, the experimental results demonstrate the effectiveness of the proposed alignment system control methodology and how much beneficial it will be in real industrial applications.

Identificação na prescrição da prática em educação física: contribuição psicanalítica: IPCP

Based mainly on the works of Sigmund Freud, Paul Schilder, Francoise Dolto, Wilhen Reich and Alex Lowen the present work address the initial construction of the body conception in the human being. Concepts of body image and initial postures implied in a psychoanalytical view offers a wider conception of the body-emotion dichotomy. Based on this conception one can spread the considerations about a deepening in the studies about the current mechanicist biomedical paradigms with the systemic ones.

Changes in grasping kinematics due to different start postures of the hand

It was proposed that grasping is a relatively stereotyped movement pattern which can be subdivided into the components of manipulation, transport, and orientation of the hand. However, it is still a matter of debate whether these components are independent of each other. In three experiments we altered the start posture of the hand by either changing the size of the start aperture or the orientation of the hand prior to movement onset. The variation of the aperture size primarily affected the manipulation component of the grip resulting in an overall change of the pre-shaping profile. In contrast, an alteration of the start orientation affected the manipulation and the transport components to a similar extent. These results give further evidence that hand orientation is neither planned nor controlled independently from the other movement components. Moreover, when the grip had to match specific object properties, adjustments were mainly achieved within the first movement part. In contrast, when there were no movement constraints the final finger positions were influenced by the initial start posture of the hand. We found no evidence for a fixed spatial or temporal coupling of the grasp and the transport component in our experiments.

Postural orientation in microgravity depends on straightening up movement performed

Whether the vertical body orientation depends on the initial posture and/or the type of straightening up movement is the main question raised in this paper. Another objective was to specify the compensatory role of visual input while adopting an erected posture during microgravity. The final body orientation was analysed in microgravity during parabolic flights. After either (1) straightening up movement from a crouching or (2) a sitting posture, with and without vision. The main results are the following: (1) a vertical erected final posture is correctly achieved after sit to stand movement, whereas all subjects were tilted forward after straightening up from a crouching posture and (2) vision may contribute to correct final posture. These results suggest the existence of a re-weighting of the remaining sensory information, visual information, contact cutaneous cues and proprioceptive information under microgravity condition. We can put forward the alternative hypothesis that the control of body orientation under microgravity condition may also be achieved on the basis of a postural body scheme, that seems to be dependant on the type of movement and/ or the initial position of the whole body.

Weight distribution influences the time required to lift the leg even under normal standing condition

The purpose of the present study is to demonstrate whether the time taken to initiate a lift-one-leg task from a quiet standing position is determined by the initial weight distribution (WD), irrespective of whether the initial posture is controlled spontaneously or by using visual feedback. Seven healthy young subjects performed a lift-one-leg task in response to visual stimulation provided by an LED. The experiment included the normal (N) condition in which the participants stand on both legs symmetrically, as subjectively estimated, and the three feedback (FL, FC and FR) conditions in which the participants regulate the WD at −20% (left-weighted by 6:4), 0% (center-weighted by 5:5) and 20% (right-weighted by 4:6), respectively, through the use of visual feedback. In the N condition, the inter-trial variation of WD was larger than that of the FC condition, which was enough to significantly correlate with the time required to lift the leg. The slope, intercept, and standard error of estimation of the regression equation between the WD and the duration of anticipatory postural adjustment were consistent between conditions. The quantification of the effect of WD on anticipatory postural adjustment indicated that the time taken to lift the leg was delayed by 2.81 ms as the center of mass shifted toward the lifting leg by 1 mm. Our results demonstrate that asymmetric loading is a simple biomechanical factor that determines the time needed to initiate a subsequent lift-one-leg task.

418 後面衝突時における頚部傷害に及ぼす頭部初期姿勢の影響

In this study, the effect of head posture on neck injury during rear-end impact was studied. First, a head-neck FE model was developed. Second, the behavior of the model during low-speed rear-impact, lateral bending and axial rotation was validated against experimental results. Third, rear impact simulations with 3 types of initial head postures including head-forward, lateral bending and axial rotation were conducted. Finally, the difference of the model behavior among 2 simulations was clarified, and that facet ligament strain during lateral bending and axial rotation simulation might exceed the strain during head-forward simulation was also clarified.

Biomechanical analysis of the relation between movement time and joint moment development during a sit-to-stand task

BackgroundSlowness of movement is a factor that may cause a decrease of quality of daily life. Mobility in the elderly and people with movement impairments may be improved by increasing the quickness of fundamental locomotor tasks. Because it has not been revealed how much muscle strength is required to improve quickness, the purpose of this study was to reveal the relation between movement time and the required muscle strength in a sit to stand (STS) task. Previous research found that the sum of the peak hip and knee joint moments was relatively invariant throughout a range of movement patterns (Yoshioka et al., 2007, Biomedical Engineering Online 6:26). The sum of the peak hip and knee joint moment is an appropriate index to evaluate the muscle strength required for an STS task, since the effect of the movement pattern variation can be reduced, that is, the results can be evaluated purely from the viewpoint of the movement times. Therefore, the sum of the peak hip and knee joint moment was used as the index to indicate the required muscle strength.MethodsExperimental kinematics data were collected from 11 subjects. The time at which the vertical position of the right shoulder fell outside three standard deviations of the vertical positions during the static initial posture was regarded as the start time. The time at which the vertical position fell within three standard deviations of the vertical positions during static upright standing posture was regarded as the finish time. Each movement time of the experimental movements was linearly lengthened and shortened through post-processing. Combining the experimental procedure and the post-processing, movements having various movement patterns and a wide range of movement times were obtained. The joint moment and the static and inertial components of the joint moment were calculated with an inverse dynamics method. The static component reflects the gravitational and/or external forces, while the inertial component reflects the acceleration of the body.ResultsThe quantitative relation between the movement time and the sum of the peak hip and knee joint moments were obtained. As the STS movement time increased, the joint moments decreased exponentially and converged to the static component (1.51 ~ 1.54 N.m/kg). When the movement time was the longest (movement time: 7.0 seconds), the joint moments (1.57 N.m/kg) closely corresponded to the minimum of 1.53 N.m/kg as reported by Yoshioka et al..ConclusionThe key findings of this study are as follows. (1) The minimum required joint moment for an STS task is essentially equivalent to the static component of the joint moment. (2) For fast and moderate speed movements (less than 2.5 seconds), joint moments increased exponentially as the movement speed increased. (3) For slow movements greater than 2.5 seconds, the joint moments were relatively constant. The results of this STS research has practical applications, especially in rehabilitations and exercise prescription where improved movement time is an intended target, since the required muscle strength can be quantitatively estimated.

The coordination of upper and lower arm rotation

We tested the hypothesis that the upper and lower arm act as a coordinative structure coupled through a higher order control system. Five healthy participants moved their hand between two targets in ten conditions via internal/external rotation of the shoulder. In eight conditions, the task required concurrent rotation of the lower arm (180 degrees pronation/supination). Movements were stereotypical within a condition but plotting the upper and lower arm angle against each other produced an asymmetrical pattern. With internal rotation, the upper arm reached peak angular velocity slower than the lower arm but this was reversed with external rotation. In two conditions, participants were asked to move faster and slower than their normal speed. The peak speed, time to peak speed and duration were predictable for the different tasks. Internal and external asymmetries decreased with faster movements. In addition a decrease in upper arm amplitude (from 90 degrees to 30 degrees) removed the asymmetry. The asymmetry was unaffected by initial posture but was exaggerated when external rotation was paired with pronation rather than supination, and internal rotation combined with supination (versus pronation). However, the presence of the same fundamental pattern suggests that the asymmetry is not due to biomechanical factors but might arise because of the difficulties involved in visually monitoring the hand when it is close to the body. The results support the idea that functional coupling can occur between upper and lower arm rotations and thus provides further evidence for a higher order control system which is responsible for coordination of arm segment movement.

A neural network model for predicting postures during non-repetitive manual materials handling tasks

Posture prediction can be useful in facilitating the design and evaluation processes for manual materials handling tasks. This study evaluates the ability of artificial neural network models to predict initial and final lifting postures in 2-D and 3-D scenarios. Descriptors for the participant and condition of interest were input to the models; outputs consisted of posture-defining joint angles. Models were trained with subsets of an existing posture database before predictions were generated. Trained models predictions were then evaluated using the remaining data, which included conditions not presented during training. Prediction errors were consistent across these data subsets, suggesting the models generalised well to novel conditions. The models generally predicted whole-body postures with per-joint errors in the 5°–20° range, though some errors were larger, particularly for 3-D conditions. These models provided reasonably accurate predictions, even outperforming some computational approaches previously proposed for similar purposes. Suggestions for future refinement of such models are presented. The models in this investigation provide a means to predict initial and final postures in commonly occurring manual materials handling tasks. In addition, the model structures provide information about potential lifting strategies that may be used by individuals with particular anthropometry or strength characteristics.

P105 A comparison of hamstring and patellar bone tendon autografts for ACL reconstruction in terms of quantitative gait data

Despite the ongoing evolution of anterior cruciate ligament injury prevention methods, injury rates and the associated sex-disparity remain. Strategies capable of successfully countering key control parameters existent within the injury mechanism thus remain elusive. Forward dynamics model simulations afford an expedited means to study realistic injury causing scenarios, while controlling all facets of the movement control strategy. Utilizing these methods, the current study examined the potential for perturbations in key initial contact neuromuscular parameters to injure the anterior cruciate ligament during the stance phase of sidestep cutting maneuvers.Controlled experiments were performed on optimized and validated subject-specific forward dynamic musculoskeletal sidestep models generated from 10 male and 10 female data sets. Random perturbations (n = 5000) were applied to initial contact kinematic and muscle activation parameters in these baseline models and then to those with prescribed systematic modifications in initial hip and knee flexion, hip internal rotation and hip internal rotation velocity postures. The number of injuries via an isolated anterior tibial shear (>2000 N) or knee valgus load (>125 Nm) mechanism was determined for each of the seven model conditions and subsequently compared.Neuromuscular control perturbations produced peak stance phase (0–100 ms) knee valgus loads large enough to induce anterior cruciate ligament injury. Decreases and increases in combined initial contact hip and knee flexion postures and hip internal rotation velocity produced significant increases and decreases in these valgus-induced ACL injury rates respectively.Anterior cruciate ligament injury via a valgus load mechanism is more likely during sidestepping when landing in a more extended posture, or with increased hip external rotation velocity. The fact that injury rates are reduced when these control parameters are reversed suggests they should be central to ongoing prevention strategy developments.

Humans adjust control to initial squat depth in vertical squat jumping

The purpose of this study was to gain insight into the control strategy that humans use in jumping. Eight male gymnasts performed vertical squat jumps from five initial postures that differed in squat depth (P1-P5) while kinematic data, ground reaction forces, and electromyograms (EMGs) of leg muscles were collected; the latter were rectified and smoothed to obtain SREMGs. P3 was the preferred initial posture; in P1, P2, P4, and P5 height of the mass center was +13, +7, -7 and -14 cm, respectively, relative to that in P3. Furthermore, maximum-height jumps from the initial postures observed in the subjects were simulated with a model comprising four body segments and six Hill-type muscles. The only input was the onset of stimulation of each of the muscles (Stim). The subjects were able to perform well-coordinated squat jumps from all postures. Peak SREMG levels did not vary among P1-P5, but SREMG onset of plantarflexors occurred before that of gluteus maximus in P1 and > 90 ms after that in P5 (P < 0.05). In the simulation study, similar systematic shifts occurred in Stim onsets across the optimal control solutions for jumps from P1-P5. Because the adjustments in SREMG onsets to initial posture observed in the subjects were very similar to the adjustments in optimal Stim onsets of the model, it was concluded that the SREMG adjustments were functional, in the sense that they contributed to achieving the greatest jump height possible from each initial posture. For the model, we were able to develop a mapping from initial posture to Stim onsets that generated successful jumps from P1-P5. It appears that to explain how subjects adjust their control to initial posture there is no need to assume that the brain contains an internal dynamics model of the musculoskeletal system.

The Relationship between Joint Strength and Standing Vertical Jump Performance

The effect of joint strengthening on standing vertical jump height is investigated by computer simulation. The human model consists of five rigid segments representing the feet, shanks, thighs, HT (head and trunk), and arms. Segments are connected by frictionless revolute joints and model movement is driven by joint torque actuators. Each joint torque is the product of maximum isometric torque and three variable functions of instantaneous joint angle, angular velocity, and activation level, respectively. Jumping movements starting from a balanced initial posture and ending at takeoff are simulated. A matching simulation reproducing the actual jumping movement is generated by optimizing joint activation level. Simulations with the goal of maximizing jump height are repeated for varying maximum isometric torque of one joint by up to +/-20% while keeping other joint strength values unchanged. Similar to previous studies, reoptimization of activation after joint strengthening is necessary for increasing jump height. The knee and ankle are the most effective joints in changing jump height (by as much as 2.4%, or 3 cm). For the same amount of percentage increase/decrease in strength, the shoulder is the least effective joint (which changes height by as much as 0.6%), but its influence should not be overlooked.

Head-Turned Postures Increase the Risk of Cervical Facet Capsule Injury During Whiplash

In vitro experiments using cadaveric cervical spine motion segments to quantify facet capsular ligament strain during whiplash-like loading. To quantify facet capsule strains during whiplash-like loading with an axial intervertebral prerotation simulating an initial head-turned posture and to then compare these strains to previously-published strains for partial failure and gross failure of the facet capsule for these specimens. Clinical data have shown that a head-turned posture at impact increases the severity and duration of whiplash-related symptoms. Thirteen motion segments were used from 7 women donors (50 +/- 10 years). Axial pretorques (+/-1.5 Nm), axial compressive preloads (45, 197, and 325 N), and quasi-static shear loads (posteriorly-directed horizontal forces from 0 to 135 N) were applied to the superior vertebral body to simulate whiplash kinematics with the head turned. Three-dimensional displacements of markers placed on the right facet capsular ligament were used to estimate the strain field in the ligament during loading. The effects of pretorque direction, compression, and posterior shear on motion segment motion and maximum principal strain in the capsule were examined using repeated-measures analyses of variance. Axial pretorque affected peak capsule strains more than axial compression or posterior shear. Peak strains reached 34% +/- 18% and were higher for pretorques toward rather than away from the facet capsule (i.e.-, head rotation to the right caused higher strain in the right facet capsule). Compared to previously-reported data for these specimens, peak capsule strains with a pretorque were double those without a pretorque (17% +/- 6%) and not significantly different from those at partial failure of the ligament (35% +/- 21%). Thus a head-turned posture increases facet capsular ligament strain compared to a neutral head posture-a finding consistent with the greater symptom severity and duration observed in whiplash patients who have their head turned at impact.

Investigating isolated neuromuscular control contributions to non-contact anterior cruciate ligament injury risk via computer simulation methods

Background Despite the ongoing evolution of anterior cruciate ligament injury prevention methods, injury rates and the associated sex-disparity remain. Strategies capable of successfully countering key control parameters existent within the injury mechanism thus remain elusive. Forward dynamics model simulations afford an expedited means to study realistic injury causing scenarios, while controlling all facets of the movement control strategy. Utilizing these methods, the current study examined the potential for perturbations in key initial contact neuromuscular parameters to injure the anterior cruciate ligament during the stance phase of sidestep cutting maneuvers. Methods Controlled experiments were performed on optimized and validated subject-specific forward dynamic musculoskeletal sidestep models generated from 10 male and 10 female data sets. Random perturbations ( n = 5000) were applied to initial contact kinematic and muscle activation parameters in these baseline models and then to those with prescribed systematic modifications in initial hip and knee flexion, hip internal rotation and hip internal rotation velocity postures. The number of injuries via an isolated anterior tibial shear (>2000 N) or knee valgus load (>125 Nm) mechanism was determined for each of the seven model conditions and subsequently compared. Findings Neuromuscular control perturbations produced peak stance phase (0–100 ms) knee valgus loads large enough to induce anterior cruciate ligament injury. Decreases and increases in combined initial contact hip and knee flexion postures and hip internal rotation velocity produced significant increases and decreases in these valgus-induced ACL injury rates respectively. Interpretation Anterior cruciate ligament injury via a valgus load mechanism is more likely during sidestepping when landing in a more extended posture, or with increased hip external rotation velocity. The fact that injury rates are reduced when these control parameters are reversed suggests they should be central to ongoing prevention strategy developments.

Laser Pose Estimation and Tracking Using Fuzzy Extended Information Filtering for an Autonomous Mobile Robot

This paper presents methodologies and techniques for posture estimation and tracking of an autonomous mobile robot (AMR) using a laser scanner with at least three retro-reflectors. A three-point laser triangulation method is presented to find an initial posture of the robot and then a fuzzy extended information filtering (FEIF) method is used to improve the accuracy of the robot's posture estimation. With the odometric information from the driving wheels, a FEIF-based posture tracking algorithm is proposed to continuously keep trace of the robot's posture at slow speeds. Simulation and experimental results are conducted to show the efficacy and usefulness of the proposed methods.

Biomechanical Analysis of Older Adults Stepping Up: A Method of Evaluating Balance

The aim of this study was to analyze differences in biomechanical parameters between elderly and control participants when stepping up, to evaluate control of balance. Eleven control and 14 elderly participants performed a step from an initial static posture onto a 7-cm-high force plate. For the spontaneous-velocity condition, elderly participants performed a slower progression velocity than control participants. Elderly participants spent proportionally more time in stance phase, with a corresponding decrease in swing phase, than the control participants, irrespective of movement velocity. In contrast, at spontaneous velocity the parameters related to ground-reaction force (GRF) showed that anteroposterior and mediolateral forces at toe-off of the support limb and the slope of vertical force during weight transfer were significantly smaller for the elderly than for control participants. These GRF parameters depended on the stepping-up velocity. The elderly develop a spatiotemporal strategy and reduced movement velocity to control support balance.

Adjustment of Home Posture of Biped Humanoid Robot Using Sensory Feedback Control

Humanoid robot dynamic walking is seriously affected by the initial home posture (walking ready posture). If the initial home posture is not accurate, the robot may fall down during walking despite using robust walking control algorithm. Moreover, the initial home posture of a real physical robot is slightly different at every setting because the zero position of the joint is not exactly the same. Therefore, an accurate and consistent initial home posture is essential when we compare and analyze walking control algorithms. In order to find a zero position, an incremental encoder with a limit switch or an absolute encoder such as a potentiometer can generally be used. However, the initial calibration of this method for a multi-axis humanoid robot that enables the desired initial sensor signal is difficult and time-consuming. Furthermore, it has the disadvantage that additional limit switches or absolute encoders can interfere with the design objective of compactness. Therefore, this paper describes a novel adjustment method of the home posture for a biped humanoid robot utilizing incremental encoders, an inertial sensor and force torque sensors. Four kinds of controllers are proposed for the adjustment of the home posture and adjusted offsets are measured when the outputs of the controllers have converged. Experimental results from KHR-2 show the effectiveness of the proposed adjustment algorithm.

2926 1脚ロボットに対する屈伸動作の安定化制御に関する研究(G10-5 機械力学・計測制御(5) 運動と振動の制御,21世紀地球環境革命の機械工学:人・マイクロナノ・エネルギー・環境)

This paper reports with respect to the stabilized motion control of a one-legged robot. Two kinds of controls are tried to the virtual inverted pendulum that is supposed through a center of gravity from the first joint. One of the controls is the optimal regulator control, and another is VSS adaptive control. In this experiment, the state of standing on tiptoe is considered to be initial posture. The sine wave-command disturbance is given to the second joint and third joint, and these controls are evaluated by the deviation angle of the pendulum. Finally, the validity of VSS adaptive control is confirmed through the experiment.

1A1-B03 凹凸鉄板面で高い吸着力を生成する永久磁石ユニットの開発(アクチュエータの機構と制御)

Magnetic adsorption device is the one of the important technological elements indispensable for the development of the robot industry, for example, the wall climbing robot. But, the important problem is that the adsorptive power decreases remarkably on the any convex part, any rivet and any welding part, as compared on a flat iron side. For solving this problem, the movable yoke, as according to the magnetic flux changing, is set in the steady yoke where a permanent magnet was fixed. As a result, the big adsorptive power is obtained such as on the convex part. Moreover, the movable yoke returns to initial posture after separating. The report shows that the new mechanism generates a strong magnetic adsorptive power by using Steady yoke and Movable yoke on the ruggedness iron plate.

The mechanisms that enable arm motion to enhance vertical jump performance—A simulation study

The reasons why using the arms can increase standing vertical jump height are investigated by computer simulations. The human models consist of four/five segments connected by frictionless joints. The head–trunk–arms act as a fourth segment in the first model while the arms become a fifth segment in the second model. Planar model movement is actuated by joint torque generators. Each joint torque is the product of three variable functions of activation level, angular velocity dependence, and maximum isometric torque varying with joint angle. Simulations start from a balanced initial posture and end at jump takeoff. Jump height is maximized by finding the optimal combination of joint activation timings. Arm motion enhances jumping performance by increasing mass center height and vertical takeoff velocity. The former and latter contribute about 1/3 and 2/3 to the increased height, respectively. Durations in hip torque generation and ground contact period are lengthened by swinging the arms. Theories explaining the performance enhancement caused by arms are examined. The force transmission theory is questionable because shoulder joint force due to arm motion does not precisely reflect the change in vertical ground reaction force. The joint torque/work augmentation theory is acceptable only at the hips but not at the knees and ankles because only hip joint work is considerably increased. The pull/impart energy theory is also acceptable because shoulder joint work is responsible for about half of the additional energy created by arm swings.