Arm Speed Research Articles

Impact of ball weight on medial elbow torque in youth baseball pitchers

Our hypothesis was that an increase in ball weight would result in an increase in medial elbow torque during the pitching motion. Youth pitchers were recruited for this study and instructed to throw 5 maximum-effort fastballs from ground level using baseballs of 4 different weights: 85 g (3 oz), 113 g (4 oz), 142 g (5 oz), and 170 g (6 oz). The validated Motus sensor was used to assess medial elbow torque, arm speed, arm slot, and shoulder rotation for each pitch. Pitch velocity was measured using a radar gun. Relationships between baseball weight and pitching kinetics and/or kinematics were evaluated using linear mixed-effects analysis. An exit survey was conducted detailing the pitcher's evaluation of the ball weights used. A total of 19 youth baseball pitchers (average age, 11.8 ± 1.1 years; age range, 9-14 years) completed the study. For every 1-oz (28-g) increase in ball weight, ball velocity decreased 2.0 ± 0.1 mph (χ2 = 52.68, P < .001), medial elbow torque increased 0.92 ± 0.37 newton meters (χ2 = 5.36, P = .02), and arm speed decreased 8.52 ± 3.68 rpm (χ2 = 5.03, P = .02). Shoulder rotation and arm slot were not significantly impacted by ball weight (P > .05). Survey results indicated that the 85-g(3-oz) baseball was most favored (8 of 19 pitchers) and believed to result in the highest pitch velocity (15 of 19 pitchers). The 170-g(6-oz) baseball was least favored (17 of 19 pitchers) and believed to result in the slowest pitch velocity (18 of 19 pitchers). No adverse outcomes were reported with the use of any ball weight or the mobile sensor. Among youth pitchers, an increase in ball weight correlated with greater medial elbow torque, decreased pitch velocity, and decreased arm speed.

Exploring wearable sensors as an alternative to marker-based motion capture in the pitching delivery.

BackgroundImprovements in data processing, increased understanding of the biomechanical background behind kinetics and kinematics, and technological advancements in inertial measurement unit (IMU) sensors have enabled high precision in the measurement of joint angles and acceleration on human subjects. This has resulted in new devices that reportedly measure joint angles, arm speed, and stresses to the pitching arms of baseball players. This study seeks to validate one such sensor, the MotusBASEBALL unit, with a marker-based motion capture laboratory.HypothesisWe hypothesize that the joint angle measurements (“arm slot” and “shoulder rotation”) of the MotusBASEBALL device will hold a statistically significant level of reliability and accuracy, but that the “arm speed” and “stress” metrics will not be accurate due to limitations in IMU technology.MethodsA total of 10 healthy subjects threw five to seven fastballs followed by five to seven breaking pitches (slider or curveball) in the motion capture lab. Subjects wore retroreflective markers and the MotusBASEBALL sensor simultaneously.ResultsIt was found that the arm slot (R = 0.975, P < 0.001), shoulder rotation (R = 0.749, P < 0.001), and stress (R = 0.667, P = 0.001 when compared to elbow torque; R = 0.653, P = 0.002 when compared to shoulder torque) measurements were all significantly correlated with the results from the motion capture lab. Arm speed showed significant correlations to shoulder internal rotation speed (R = 0.668, P = 0.001) and shoulder velocity magnitude (R = 0.659, P = 0.002). For the entire sample, arm slot and shoulder rotation measurements were on a similar scale, or within 5–15% in absolute value, of magnitude to measurements from the motion capture test, averaging eight degrees less (12.9% relative differences) and nine degrees (5.4%) less, respectively. Arm speed had a much larger difference, averaging 3,745 deg/s (80.2%) lower than shoulder internal rotation velocity, and 3,891 deg/s (80.8%) less than the shoulder velocity magnitude. The stress metric was found to be 41 Newton meter (Nm; 38.7%) less when compared to elbow torque, and 42 Nm (39.3%) less when compared to shoulder torque. Despite the differences in magnitude, the correlations were extremely strong, indicating that the MotusBASEBALL sensor had high reliability for casual use.ConclusionThis study attempts to validate the use of the MotusBASEBALL for future studies that look at the arm slot, shoulder rotation, arm speed, and stress measurements from the MotusBASEBALL sensor. Excepting elbow extension velocity, all metrics from the MotusBASEBALL unit showed significant correlations to their corresponding metrics from motion capture and while some magnitudes differ substantially and therefore fall short in validity, the link between the metrics is strong enough to indicate reliable casual use. Further research should be done to further investigate the validity and reliability of the arm speed metric.

Decoding arm speed during reaching

Neural prostheses decode intention from cortical activity to restore upper extremity movement. Typical decoding algorithms extract velocity—a vector quantity with direction and magnitude (speed) —from neuronal firing rates. Standard decoding algorithms accurately recover arm direction, but the extraction of speed has proven more difficult. We show that this difficulty is due to the way speed is encoded by individual neurons and demonstrate how standard encoding-decoding procedures produce characteristic errors. These problems are addressed using alternative brain–computer interface (BCI) algorithms that accommodate nonlinear encoding of speed and direction. Our BCI approach leads to skillful control of both direction and speed as demonstrated by stereotypic bell-shaped speed profiles, straight trajectories, and steady cursor positions before and after the movement.

Adaptive visual servoing control for an underwater soft robot

PurposeSoft robotics, regarded as a new research branch of robotics, has generated increasing interests in this decade and has demonstrated its outperformance in addressing safety issues when cooperating with human beings. However, there is still lack of accurate close-loop control because of the difficulty in acquiring feedback information and accurately modeling the system, especially in interactive environments. To this end, this paper aims to improve the controllability of the soft robot working in specific underwater environment. The system dynamics, which takes complicated hydrodynamics into account, is solved using Kane’s method. The dynamics-based adaptive visual servoing controller is proposed to realize accurate sensorimotor control.Design/methodology/approachThis paper presents an image-based visual servoing control scheme for a cable-driven soft robot with a fixed camera observing the motions. The intrinsic and extrinsic parameters of the camera can be adapted online so that tedious camera calibration work can be eliminated. It is acknowledged that kinematics-based control can be only applied into tasks in the free space and has limitation in accelerating the motion speed of robot arms. That is, one must consider the unneglectable interaction effects generated from the environment and objectives when operating soft robots in such interactive control tasks. To extend the application of soft robots into underwater environment, the study models system dynamics considering complicated hydrodynamic effects. With the pre-knowledge of the external effects, the performance of the robot can be further improved by adding the compensation term into the controller.FindingsThe proposed controller has theoretically proved its convergence of image error, adaptive estimation error and the stability of the dynamical system based on Lyapunov’s analysis. The authors also validate the performance of the controller in positioning control task in an underwater environment. The controller shows its capacity of rapid convergence to and accurate tracking performance of a static image target in a physical experiment.Originality/valueTo the best of the authors’ knowledge, there is no such research before that has developed dynamics-based visual servoing controller which takes into account the environment interactions. This work can thus improve the control accuracy and enhance the applicability of soft robotics when operating in complicated environments.

Changes in Throwing Arm Mechanics at Increased Throwing Distances During Structured Long-Toss

Background: Elbow injuries among adolescent baseball players have been outpacing those of college and professional players. In attempts to prevent injuries and maximize return-to-play potential following injury, attention has been focused on “return to throw” programs, which include long-toss throws. Because the few studies that were conducted on long-toss throwing focused primarily on college-aged athletes, it is not known what type of load is incurred at the elbow during interval throwing progression among high school baseball players. Purpose: To quantify the change in arm slot, arm speed, shoulder external rotation, and elbow varus torque across increasing throwing distances within a given athlete. Study Design: Descriptive laboratory study. Methods: Ninety-five high school baseball players performed a long-toss protocol while wearing an inertial sensor and sleeve. Each participant was tested for 5 throws at distances of 9 m, 18 m, 27 m, 37 m, and 46 m. Linear mixed-effects models and likelihood ratio tests were used to estimate the within-participant relationship between throw distance and arm slot, arm speed, shoulder external rotation, and elbow varus torque. Results: Arm slot (P < .01), arm speed (P < .01), shoulder external rotation (P < .01), and elbow varus torque (P < .01) were significantly associated with long-toss throw distance. As the throw distance increased, there was an increase in arm speed and shoulder external rotation and a decrease in arm slot for each distance. However, elbow varus torque increased with each distance up to 37 m and then remained the same at 46 m. Conclusion: The use of longer distances for conditioning and rehabilitation may be beneficial in increasing shoulder range of motion and arm speed; however, precaution needs to be taken, as throwing longer distances are accompanied by an increase in arm rotation, arm speed, and elbow torque, with a decrease in arm slot. Clinical Relevance: Return-to-throw programs have been utilized by sports medicine clinicians and coaches to help guide a player during rehabilitation. These programs involve throwing at increased efforts through increased distances with no immediate feedback on elbow stress. This investigation describes arm biomechanical changes during submaximum interval throwing and demonstrates a tool that can be utilized to measure arm stress in real time for clinicians and athletes progressing through an interval throwing program.

Relationship Between Pitcher Fatigue and Medial Elbow Torque in Baseball Pitchers: A Simulated Game Analysis

Objectives:The incidence of overuse injury to the elbow in baseball pitchers continues to rise, despite exhaustive efforts at pitch count regulations and emphasis on proper throwing mechanics. The goal of this study was to determine if the medial elbow experiences increased torque levels as the pitcher fatigues through the course of a simulated game.Methods:Competitive baseball pitchers were recruited for this simulated game study. Medial elbow torque was assessed using a validated mobile sensor that recorded medial elbow torque during the throwing motion. A radar gun was used to capture pitch velocity for each recorded pitch. Each pitcher completed a simulated game consisting of 6 innings and a standardized pitching scheme of fastballs, curveballs, and change-ups. Visual analog scores (VAS) measuring fatigue were recorded in between each inning. In total, each pitcher threw 90 pitches. Data was recorded every pitch to include ball velocity, medial elbow torque, arm speed, arm rotation, and arm slot.Results:A total of 11 pitchers (average age 17.6 years; range 15-20 years) completed the study. No adverse outcomes were noted with use of the mobile sensor. VAS scores increased 0.716 points per inning pitched (p<0.001). Medial elbow torque also was found to increase with successive innings, with an increase of 0.836 Nm each inning (p<0.001), while average pitch velocity was found to decrease as the game progressed (0.28 mile per hour decrease per inning; p<0.001). Fastballs generated the highest amount of medial elbow torque. There were no differences found in arm rotation or arm speed as the game progressed. However, the arm slot was found to decrease with each successive inning (0.731 degree decrease per inning; p<0.001).Conclusion:In this simulated game analysis, pitchers were noted to experience increase fatigue after each successive inning. While the average fastball velocity decreased from inning-to-inning, the medial elbow torque was found to increase, signifying a possible risk factor for overuse injury to the medial elbow.

Effect of Fatigue on Medial Elbow Torque in Baseball Pitchers: A Simulated Game Analysis

Background: The incidence of overuse injury to the elbow among baseball pitchers continues to rise, despite extensive efforts at pitch count regulations and emphasis on proper throwing mechanics. Purpose: To determine if the medial elbow experiences increased torque levels as a baseball pitcher fatigues through the course of a simulated game. Study Design: Descriptive laboratory study. Methods: High school and collegiate baseball pitchers were recruited for this simulated game study. Each pitcher completed a simulated game consisting of 6 innings and a standardized pitching scheme of fastballs, curveballs, and changeups. In total, each pitcher threw 90 pitches. Fatigue was reported per inning with a visual analog scale, and pitch velocity was captured per pitch with a radar gun. Outcome measures were assessed with a validated mobile sensor and included medial elbow torque, arm speed, arm rotation, and arm slot. Linear and quadratic regression modeling was used to evaluate the relationship between pitcher fatigue and pitching kinematics. Results: A total of 11 pitchers (mean age, 17.6 years; range, 15-20 years) completed the study. Visual analog scale fatigue scores increased 0.72 points per inning pitched (P < .01, effect size = 0.64). Medial elbow torque also increased beyond inning 3, with an increase of 0.84 N·m each inning (P < .01, effect size = 0.08), while pitch velocity decreased (0.28 mph per inning, P < .01, effect size = 0.27). Fastballs generated the greatest amount of medial elbow torque (49.3 ± 1.4 N·m, P < .01, effect size = 0.24). There were no differences in arm rotation (P = .42) or arm speed (P = .80) as the game progressed. However, arm slot decreased with each successive inning (0.73° on average per inning, P = .03, effect size = 0.12). No adverse outcomes were noted with use of the mobile sensor. Conclusion: In this simulated game analysis, pitchers experienced increased fatigue after each successive inning. While the average pitch velocity declined with each successive inning, the torque on the medial elbow increased after inning 3. These findings signify a possible relationship between fatigue and injury risk.

Predictors of Elbow Torque Among Youth and Adolescent Baseball Pitchers

Background: There has been an increasing incidence of overuse elbow injuries among youth and adolescent pitchers. Pitch type has been implicated as a risk factor for excess torque at the medial elbow; however, this has not been definitively demonstrated. Purpose: To assess predictors of torque across the medial elbow in youth and adolescent pitchers with a mobile sensor. In addition, the authors aimed to determine the differences in elbow torque produced according to pitch type (fastball, curveball, changeup) and pitcher demographics. Study Design: Descriptive laboratory study. Methods: Twenty youth and adolescent pitchers were instructed to throw 8 fastballs, 8 curveballs, and 8 changeups in a standardized but randomized sequence over a 25-minute period. Five pitchers were evaluated each day. A sensor placed at the medial elbow reported elbow torque, arm speed, arm slot, and shoulder rotation for each pitch, while a radar gun measured peak ball velocity. The primary outcome was a determination of thrower and pitch characteristics associated with elevated torque across the medial elbow. Secondary outcomes included the evaluation of differences in throwing biomechanics among different pitch types. Outcomes were assessed via a multivariable model, which controlled for possible covariates. Results: In total, 20 youth baseball pitchers with a mean age of 14.1 years (range, 12-17 years) were included in the study. On average, fastballs caused the greatest torque across the medial elbow (least squares mean ± SE, 47.3 ± 0.5 N·m) as compared with changeups (44.2 ± 0.5 N·m; P < .001) and curveballs (45.0 ± 0.5 N·m; P = .002). However, curveballs produced the greatest arm speed (917.8 rpm). Pitchers who started throwing curveballs at an older age experienced less elbow torque (P < .001). A multivariable model demonstrated that increased ball velocity and body mass index and decreased arm slot were independent predictors of increased elbow torque. Conversely, increasing age, longer arm length, and greater elbow circumference were independent protectors against elbow torque. Conclusion: This study found that among youth and adolescent pitchers, fastballs generate the highest elbow torque while curveballs generated the greatest arm speed. Increased ball velocity and body mass index and decreased arm slot were predictors of elbow torque; however, increasing age and size of a pitcher’s arm were protectors against elbow torque. These findings are important to better understand risk factors for overuse injury in this at-risk athletic population. Clinical Relevance: These findings may inform future pitching recommendations with intentions of curtailing medial elbow injuries experienced by young pitchers, such as ulnar collateral ligament injuries.

Mixed Profile Method of Speed and Location for Robotic Arms Motion used for Precise Positioning

The paper describes a new real-time computation method named Mixt Profile of Speed (MPS), which is used to obtain the value of speed, at every sampling period of time, during the acceleration and deceleration stage, whereas the motion has three stages: 1) acceleration, 2) motion with imposed constant speed, and 3) deceleration. The method will determinate the location of a robotic arm for every sampling period of time. The originality of this new computation method refers to the deceleration stage; it determines an accurate positioning at the end of the motion in a well determinate interval of time. During the forced constant motion stage, the trajectory is imposed and it is linear or circular. The ADNIA algorithm (numerical differential analysis interpolation algorithm) can be implemented at this stage (during the motion with imposed constant speed of the robotic arm) in order to ensure the maximum precision of the computation for the waypoints Cartesian coordinates.

Assessment of Elbow Torque and Other Parameters During the Pitching Motion: Comparison of Fastball, Curveball, and Change-up

To assess the precision of a new wearable device in detecting medial elbow torque during the pitching motion in competitive baseball pitchers and to determine the differences in torque across pitch types and thrower demographic characteristics. High school and collegiate baseball pitchers were recruited from August 1, 2016, to January 31, 2017, through direct request by athletic trainers and coaches. Body dimensions and throwing arm measurements of the participants were collected. The sensor was positioned directly over the medial elbow and pitchers were instructed to throw 8 fastballs, 8 curveballs, and 8 change-ups in a standard, randomized sequence. The sensor reported elbow torque, arm speed, arm slot, and shoulder rotation, whereas a radar gun measured peak ball velocity. Precision was calculated by measuring outlier rate, and mixed model regression analysis was performed to detect differences in throwing biomechanics among pitch types. In total, 37 competitive baseball pitchers were included in the study. The device had a precision of 96.9% for fastballs, 96.9% for curveballs, and 97.9% for change-ups. The device was sensitive enough to distinguish pitches according to elbow torque, arm speed, arm slot, and shoulder rotation. Fastballs caused the greatest relative torque across the medial elbow (average= 45.56Nm), compared with change-ups (43.77Nm; P= .006) and curveballs (43.83Nm; P= .01). Ball velocity contributed most to medial elbow torque (P= .003), followed by elbow circumference (P= .021), where smaller elbow circumference predicted greater medial elbow torque. The sensor is a precise and reproducible device for measuring torque across the medial elbow, as well as additional parameters of arm speed, arm slot, and shoulder rotation. Torque was significantly relatively higher in fastballs than curveballs and change-ups. Level III, comparative study.

Effects of nine weeks isokinetic training on power, golf kinematics, and driver performance in pre-elite golfers

BackgroundIt has previously been shown that isotonic strength training can improve driver performance among golfers, though few studies have investigated effects of strength training on swing kinematics together with driver performance. In this study we investigated whether isokinetic rotational training could improve driver performance and swing kinematic variables amongst elite golfers.MethodsTwenty competitive pre-elite golfers (handicap better than −3.0), 13 men and 7 women, were split into two groups, one group received the isokinetic power training (IK) alongside their normal isotonic pre-season strength-training and the other group continued with their normal isotonic pre-season strength-training regime (IT). The IK group completed 12 sessions of isokinetic power training on a standing rotation exercise (10% body weight at 1 m/s) and barbell squat (25 kg plus 10% body weight at 0.5 m/s). The IT group continued with their normal isotonic pre-season strength-training regime. Participants were tested for rotational power, lower body power, golf swing kinematics, and driver performance before and after a nine-week training period.ResultsAfter the nine-week training period both the IK and the IT groups increased their dominant side rotational force and power (effect sizes between 0.50–0.96) and magnitude based inference indicated that IK had a likely (> 80%) more beneficial increase in dominant side rotational force and power. For swing kinematics, IK had a likely (> 80%) more beneficial improvement in lead arm speed and acceleration compared to the IT group. For driver performance, IK had a possible (65%) beneficial effect on ball speed and likely (78%) beneficial effect on carry distance when compared to IT, whereas neither of the groups improved club head speed.ConclusionIn the present study on pre-elite golfers we found that 9 weeks of isokinetic training increased seated rotational force and power, peak arm speed and arm acceleration, ball speed, and carry distance more compared to isotonic training. Even though isokinetic training did not increase CHS, it did result in greater carry distance.

The Relationship of Throwing Arm Mechanics and Elbow Varus Torque: Within-Subject Variation for Professional Baseball Pitchers Across 82,000 Throws

Background: Likely due to the high level of strain exerted across the elbow during the throwing motion, elbow injuries are on the rise in baseball. To identify at-risk athletes and guide postinjury return-to-throw programs, a better understanding of the variables that influence elbow varus torque is desired. Purpose: To describe the within-subject relationship between elbow varus torque and arm slot and arm rotation in professional baseball pitchers. Study Design: Descriptive laboratory study. Methods: A total of 81 professional pitchers performed 82,000 throws while wearing a motusBASEBALL sensor and sleeve. These throws represented a combination of throw types, such as warm-up/catch, structured long-toss, bullpen throwing from a mound, and live game activity. Variables recorded for each throw included arm slot (angle of the forearm relative to the ground at ball release), arm speed (maximal rotational velocity of the forearm), arm rotation (maximal external rotation of the throwing arm relative to the ground), and elbow varus torque. Linear mixed-effects models and likelihood ratio tests were used to estimate the relationship between elbow varus torque and arm slot, arm speed, and arm rotation within individual pitchers. Results: All 3 metrics—arm slot (χ2 = 428, P < .001), arm speed (χ2 = 57,683, P < .001), and arm rotation (χ2 = 1392, P < .001)—were found to have a significant relationship with elbow varus torque. Within individual athletes, a 1-N.m increase in elbow varus torque was associated with a 13° decrease in arm slot, a 116 deg/s increase in arm speed, and an 8° increase in arm rotation. Conclusion: Elbow varus torque increased significantly as pitchers increased their arm rotation during the arm cocking phase, increased the rotational velocity of their arm during the arm acceleration phase of throwing, and decreased arm slot at ball release. Thus, shoulder flexibility, arm speed, and elbow varus torque (and likely injury risk) are interrelated and should be considered collectively when treating pitchers. Clinical Relevance: It is well established that elbow varus torque is related to ulnar collateral ligament injuries in overhead throwers. This study describes the relationship of arm slot, arm speed, and arm rotation to elbow varus torque in an attempt to identify modifiable risk factors for injury.

The Relationship of Throwing Arm Mechanics and Elbow Varus Torque: Within-subject Variation for Professional Baseball Pitchers Across 81,999 Throws

Objectives:Likely due to the high level of strain exerted across the elbow during the throwing motion, elbow injuries are on the rise in baseball. In order to identify at risk athletes and guide post-injury return to throw programs, a better understanding of the variables that influence elbow varus torque is desired. The purpose of this work was to describe the within-subject relationship between elbow varus torque and arm slot, arm speed, and shoulder rotation in professional baseball pitchers.Methods:A total of 81 professional pitchers performed 81,999 throws while wearing a motusBASEBALL sensor and sleeve (Motus Global, Massapequa, NY, USA). These throws represented a combination of throw types, such as warm-up/catch, structured long-toss, bullpen throwing from a mound, and live game activity. Variables recorded for each throw included arm slot, arm speed, shoulder rotation, and elbow varus torque. Linear mixed-effects models and likelihood ratio tests were utilized to estimate to the relationship between elbow varus torque and arm slot, arm speed, and shoulder rotation within individual pitchers.Results:All three metrics, arm slot (χ2 = 428, p<0.01), arm speed (χ2 = 57683, p<0.01), and shoulder rotation (χ2 = 1392, p<0.01), were estimated to have a significant relationship with elbow varus torque. Within individual athletes, a 1-Nm increase in elbow varus torque was associated with a 13° decrease in arm slot, a 116°/s increase in arm speed, and an 8° increase in shoulder rotation.Conclusion:Elbow varus torque increased significantly as pitchers increased shoulder rotation during the arm cocking phase and rotational velocity of the arm during the arm acceleration phase of throwing. Thus shoulder flexibility, arm speed, and elbow varus torque (and likely injury risk) are inter-related and should be considered collectively when treating pitchers.

Dynamical imprint of interstellar gas on persistence of spiral structure in galaxies

AbstractThe persistence of the spiral structure in disk galaxies has long been debated. In this work, we investigate the dynamical influence of interstellar gas on the persistence of the spiral arms in disk galaxies. We show that the gas helps the spiral arms to survive for longer time-scale (~ a few Gyr). Also, we show that the addition of gas in calculation is necessary for getting a stable density wave corresponding to the observed pattern speed of the spiral arms.

Exploring relations between EMG and biomechanical data recorded during a golf swing

A novel technique to explore relations between EMG and biomechanical data is presented.Statistically significant relations between EMG and biomechanical data were revealed.High prediction accuracy of peak angular velocity of thorax and pelvis was obtained.Insights concerning coordination of human body parts during a golf swing were obtained. Exploring relations between patterns of peak rotational speed of thorax, pelvis and arm, and patterns of EMG signals recorded from eight muscle regions of forearms and shoulders during the golf swing is the main objective of this article. The linear canonical correlation analysis, allowing studying relations between sets of variables, was the main technique applied. To get deeper insights, linear and nonlinear random forests-based prediction models relating a single output variable, e.g. a thorax peak rotational speed, with a set of input variables, e.g. an average intensity of EMG signals were used.The experimental investigations using data from 16 golfers revealed statistically significant relations between sets of input and output variables. A strong direct linear relation was observed between linear combinations of EMG averages and peak rotational speeds. The coefficient of determination values R2=0.958 and R2=0.943 obtained on unseen data by the random forest models designed to predict peak rotational speed of thorax and pelvis, indicate high modelling accuracy. However, predictions of peak rotational speed of arm were less accurate. This was expected, since peak rotational speed of arm played a minor role in the linear combination of peak speeds. The most important muscles to predict peak rotational speed of the body parts were identified. The investigations have shown that the canonical correlation analysis is a promising tool for studying relations between sets of biomechanical and EMG data. Better understanding of these relations will lead to guidelines concerning muscle engagement and coordination of thorax, pelvis and arms during a golf swing and will help golf coaches in providing substantiated advices.

Verification of Intelligent Planting Robot Arm Design Using Dynamics Analysis and Simulation

In this study, it is our goal to perform multi-body dynamics analysis and simulation analysis for robot arm which is the key driving module for planting robot system in radioactive exposed area, and to develop optimal planting robot arm through maximum speed and thrust analysis of planting robot arm. For improved lightweight model, maximum driving thrust is found as 190N, and we intend to develop model that can maintain the operation and performance of planting robot arm while minimizing the linear actuator’s load that occurs from initial model.

Dynamical effect of gas on spiral pattern speed in galaxies

In the density wave theory of spiral structure, the grand-design two-armed spiral pattern is taken to rotate rigidly in a galactic disc with a constant, definite pattern speed. The observational measurement of the pattern speed of the spiral arms, though difficult, has been achieved in a few galaxies such as NGC 6946, NGC 2997, and M 51 which we consider here. We examine whether the theoretical dispersion relation permits a real solution for wavenumber corresponding to a stable wave, for the observed rotation curve and the pattern speed values. We find that the disc when treated to consist of stars alone, as is usually done in literature, does not generally support a stable density wave for the observed pattern speed. Instead the inclusion of the low velocity dispersion component, namely, gas, is essential to obtain a stable density wave. Further, we obtain a theoretical range of allowed pattern speeds that correspond to a stable density wave at a certain radius, and check that for the three galaxies considered, the observed pattern speeds fall in the respective prescribed range. The inclusion of even a small amount (~ 15 %) of gas by mass fraction in the galactic disc is shown to have a significant dynamical effect on the dispersion relation and hence on the pattern speed that is likely to be seen in a real, gas-rich spiral galaxy.

Temporal alignment of electrocorticographic recordings for upper limb movement.

The detection of movement-related components of the brain activity is useful in the design of brain-machine interfaces. A common approach is to classify the brain activity into a number of templates or states. To find these templates, the neural responses are averaged over each movement task. For averaging to be effective, one must assume that the neural components occur at identical times over repeated trials. However, complex arm movements such as reaching and grasping are prone to cross-trial variability due to the way movements are performed. Typically initiation time, duration of movement and movement speed are variable even as a subject tries to reproduce the same task identically across trials. Therefore, movement-related neural activity will tend to occur at different times across the trials. Due to this mismatch, the averaging of neural activity will not bring into salience movement-related components. To address this problem, we present a method of alignment that accounts for the variabilities in the way the movements are conducted. In this study, arm speed was used to align neural activity. Four subjects had electrocorticographic (ECoG) electrodes implanted over their primary motor cortex and were asked to perform reaching and retrieving tasks using the upper limb contralateral to the site of electrode implantation. The arm speeds were aligned using a non-linear transformation of the temporal axes resulting in average spectrograms with superior visualization of movement-related neural activity when compared to averaging without alignment.

Digital Hardware Realization of Forward and Inverse Kinematics for a Five-Axis Articulated Robot Arm

When robot arm performs a motion control, it needs to calculate a complicated algorithm of forward and inverse kinematics which consumes much CPU time and certainty slows down the motion speed of robot arm. Therefore, to solve this issue, the development of a hardware realization of forward and inverse kinematics for an articulated robot arm is investigated. In this paper, the formulation of the forward and inverse kinematics for a five-axis articulated robot arm is derived firstly. Then, the computations algorithm and its hardware implementation are described. Further, very high speed integrated circuits hardware description language (VHDL) is applied to describe the overall hardware behavior of forward and inverse kinematics. Additionally, finite state machine (FSM) is applied for reducing the hardware resource usage. Finally, for verifying the correctness of forward and inverse kinematics for the five-axis articulated robot arm, a cosimulation work is constructed by ModelSim and Simulink. The hardware of the forward and inverse kinematics is run by ModelSim and a test bench which generates stimulus to ModelSim and displays the output response is taken in Simulink. Under this design, the forward and inverse kinematics algorithms can be completed within one microsecond.

Theoretical Analysis on Energy Consumption for Industrial Robots

This paper presents a theoretical analysis on energy consumption for industrial robots. In this project, the industrial robot used is a virtual robot resembling the FANUC LR Mate 200iB robotic arm. The first two joints consume the most electrical energy, this research focuses only on the first two joints. The calculation of the electrical energy consumed is based on a previous established research done by Herman (2009) from Universiti Teknikal Malaysia Melaka (UTeM) in the year 2009. In this research, three different time intervals were used to set the speed of the robotic arm to be at 50%, 100% and 200% speed and they were tested on 10 different angles with 10 time intervals for the 1st and the 2nd robotic joints.