Motor Control Characteristics Research Articles

Human Information Processing of the Speed of Various Movements Estimated Based on Trajectory Change.

Fitts' approach, which examines the information processing of the human motor system, has the problem that the movement speed is controlled by the difficulty index of the task, which the participant uniquely sets, but it is an arbitrary speed. This study rigorously aims to examine the relationship between movement speed and information processing using Woodworth's method to control movement speed. Furthermore, we examined movement information processing using an approach that calculates probability-based information entropy and mutual information quantity between points from trajectory analysis. Overall, 17 experimental conditions were applied, 16 being externally controlled and one being self-paced with maximum speed. Considering that information processing occurs when irregularities decrease, the point at which information processing occurs switches at a movement frequency of approximately 3.0-3.25 Hz. Previous findings have suggested that motor control switches with increasing movement speed; thus, our approach helps explore human information processing in detail. Note that the characteristics of information processing in movement speed changes that were identified in this study were derived from one participant, but they are important characteristics of human motor control.

A Study on Performance and Characteristic Analysis According to the Operating Point of IPMSM Drive

This study presents the characteristics and performance of a motor at the operating point based on pulse-width modulation (PWM). PWM is used in modulating the output voltage of a three-phase inverter. The PWM technique has advantages and disadvantages depending on the system size and operating range. For example, some discontinuous pulse-width modulation (DPWM) techniques are advantageous in low-cost systems because they can reduce the number of switches. Some PWM techniques are complicated for software construction and require a lot of computation. In this paper, PWM techniques were constructed by using the offset voltage injection method. Therefore, the construction of the PWM technique is simplified by the method. In an experimental setup, an interior permanent-magnet synchronous motor (IPMSM) and a three-phase inverter were implemented to test motor control performance depending on the PWM technique. In addition, the current control characteristics and inverter efficiency were analyzed and compared depending on the speed and load of the motor. According to the results of this paper, it is possible to compare the motor and inverter control characteristics using various types of PWM rapidly. Additionally, it will help to select an appropriate PWM technique for a specific system.

Sex-specific tuning of modular muscle activation patterns for locomotion in young and older adults.

There is increasing evidence that including sex as a biological variable is of crucial importance to promote rigorous, repeatable and reproducible science. In spite of this, the body of literature that accounts for the sex of participants in human locomotion studies is small and often produces controversial results. Here, we investigated the modular organization of muscle activation patterns for human locomotion using the concept of muscle synergies with a double purpose: i) uncover possible sex-specific characteristics of motor control and ii) assess whether these are maintained in older age. We recorded electromyographic activities from 13 ipsilateral muscles of the lower limb in young and older adults of both sexes walking (young and old) and running (young) on a treadmill. The data set obtained from the 215 participants was elaborated through non-negative matrix factorization to extract the time-independent (i.e., motor modules) and time-dependent (i.e., motor primitives) coefficients of muscle synergies. We found sparse sex-specific modulations of motor control. Motor modules showed a different contribution of hip extensors, knee extensors and foot dorsiflexors in various synergies. Motor primitives were wider (i.e., lasted longer) in males in the propulsion synergy for walking (but only in young and not in older adults) and in the weight acceptance synergy for running. Moreover, the complexity of motor primitives was similar in younger adults of both sexes, but lower in older females as compared to older males. In essence, our results revealed the existence of small but defined sex-specific differences in the way humans control locomotion and that these are not entirely maintained in older age.

Motor control characteristics for simultaneous bilateral asymmetrical tasks performed by upper limbs

Motor control characteristics for simultaneous bilateral asymmetrical tasks performed by upper limbs

Stabilometric Characteristics of the Skateboarding Athlete from the Romberg Test

This research aims to find the characteristics of motor control at the level of body stability in skateboarding athletes from the city of Bogotá through a Romberg test with eyes open and eyes closed. The present study is of a descriptive cross-sectional type and the sample selection for the development of this research was for convenience, for which a direct invitation was performed at different skateboarding clubs in the city and the league skating Bogotá who supports the sport. The sample population corresponds to 30 people with an age between 22.86 +/- 7.88 years. Participants developed Romberg test with a duration of 30 s and under the modalities eyes open and closed on a platform of plantar pressure and stabilometry BTS P-Walk. Significant changes were found in comparison of the open and closed eyes tests in the lateral flexion of the spine (LSF) with p=0.018, body center of gravity with p=0.043, left center of gravity with p=0.018, showing improvements in body stability evaluation with eyes closed. It is evident that skateboarding athletes due to the dynamics and sports development on an unstable base present a high level of stability represented in mediolateral and anteroposterior stability and variability radii close to zero, additionally it is observed that work at eye level closed generates a better sports adaptation from the vestibular and peripheral system for motor control and balance.

Head and Upper Limb Motor Control in Elementary School Children with Handwriting Difficulties

ABSTRACT Children with suspected developmental disabilities often have handwriting difficulties and show problems with motor control of the head and upper limbs, but it has not been examined in detail. The purpose of this study was to examine the characteristics of motor control in children with suspected developmental disabilities and writing difficulties. Nineteen right-handed males who were receiving support in the resource room for handwriting difficulties (SDD group) were compared with 17 right-handed age-matched male controls. Both groups completed two handwriting tasks. The main measures were jerk and changes in joint angle, which were measured by a 3D motion analysis system. The SDD group had significantly higher mean values of jerk in the head, forearms, and hands and significantly greater changes in the joint angle of neck flexion in both handwriting tasks compared to the control group. Children with suspected developmental disabilities and handwriting difficulties had less smooth forearm movements and greater fixed head movements.

Motor control characteristics of upper limbs in response to assistive forces during bilateral tasks.

Most research on power assist suits (PASs) that concerned PAS-human interactions has used human physical reactions as criteria to evaluate the mechanical function, however, with minimal emphasis on human reactions in response to PASs. In this study, we focused on the physiological responses of the upper limbs including muscle activity of the biceps brachii and the triceps brachii, co-activation, force steadiness (CV) and rated perceived exertion (RPE) to various patterns of bilateral assistive force, such as unilateral assistance (L0% & R67% [% = percentage of workload force, L = left arm, R = right arm], L67% & R0%, L0% & R33%, L33% & R0%), symmetrical (L0% & R0%, L33% & R33%, L67% & R67%) and asymmetrical bilateral assistance (L33% & R67%, L67% & R33%), during bilateral isometric force-matching tasks. The results showed a similar muscular response of the two arms to bilateral assistive conditions, and the muscle activity of the arm that was being observed decreased only when the assistive force that applied on itself increased, indicating that both arms may have adopted similar but independent motor control mechanisms to acclimate to the bilateral assistive forces. Comparison between the two unilateral assistances (L0% & R33% and L33% & R0%) and the two asymmetrical bilateral assistances (L33% & R67%, L67% & R33%) showed no significant differences in muscular responses, CV and RPE, indicating that bilateral assistances with bilateral interchanged assistive levels may be equally effective regardless of which arm the higher assistive force is applied to. Comparison between unilateral and symmetrical assistive conditions that have similar overall workloads (L67% & R0%, L33% & R33%, L0% & R67%) showed a lower CV and RPE score at symmetrical assistance compared with unilateral assistance, suggesting that assisting both arms with the same level simultaneously improves task performances compared with applying the assistive force to only one arm.

Predicting aperture crossing behavior from within-trial metrics of motor control reliability.

Actors utilize intrinsically scaled information about their geometric and dynamic properties when perceiving their ability to pass through openings. Research about dynamic factors of affordance perception have shown that the reliability of a given movement, or the precision of one's motor control for that movement, increase the buffer space used when interacting with the environment. While previous work has assessed motor control reliability as a person-level variable (i.e., behavior is aggregated across many trials), the current study assessed how characteristics of motor control and movement reliability within a single trial impact real-time action strategies for passing through apertures. Participants walked 5m and then passed through apertures of various widths while their motions were tracked. For each trial, we collected walking time-series data, then calculated the magnitude and complexity of the lateral sway. Assessing two behavioral measures of the buffer, we found that trial-level metrics of motor control reliability, in addition to the person-level metrics previously studied, significantly predicted the buffer on each trial. This study supports previous claims that actors pick up real-time information about their dynamic capabilities in order to perceive and act within their environment. Further, the study recommends that future affordance research consider trial-level movement data, including nonlinear analyses that inform the pattern and structure of motor control reliability.

Serious Game Platform with Haptic Feedback and EMG Monitoring for Upper Limb Rehabilitation and Smoothness Quantification on Spinal Cord Injury Patients

Cervical Spinal Cord injury (SCI) is a neurological disease that produces, as a consequence, impairments of the upper limb function. This paper illustrates a virtual reality platform based on three serious games for upper limb rehabilitation with electromyography monitoring, providing force feedback to the patient. In the rehabilitation process proposed, haptic feedback was provided to the patients to strength the arm muscles by means of the Novint Falcon device. This end-effector device was used to manipulate the serious games. During the therapy performance, the system recorded electromyography signals from the patient’s arm muscles, which may be used to monitor muscle contraction. The work presented a virtual reality system developed for spinal cord-injured patients. Each virtual reality environment could be modified in strength and duration according to the patients’ needs and was implemented for recording quantitative data about the motor performance. The platform was validated as a proof of concept in cervical spinal cord-injured patients. Results showed that this rehabilitation platform could be used for obtaining objective information in relation to motor control characteristics.

Analysis of Three-Dimensional Circular Tracking Movements Based on Temporo-Spatial Parameters in Polar Coordinates

Motor control characteristics of the human visuomotor control system need to be analyzed in the three-dimensional (3D) space to study and imitate human movements. In this paper, we examined circular tracking movements on two planes in 3D space from a motor control perspective based on three temporospatial parameters in polar coordinates. Sixteen healthy human subjects participated in this study and performed circular target tracking movements rotating at 0.125, 0.25, 0.5, and 0.75 Hz in the frontal or sagittal planes in three-dimensional space. The results showed that two temporal parameter errors on each plane were proportional to the change in the target velocity. Furthermore, frontal plane circular tracking errors without depth for a spatial parameter were lower than those for sagittal plane circular tracking with depth. The experimental protocol and data analysis allowed us to analyze the motor control characteristics temporospatially for circular tracking movement with various depths and speeds in the 3D VR space.

Characteristics of selective motor control of the lower extremity in adults with bilateral spastic cerebral palsy.

[Purpose] We aimed to examine the relationship between gross motor function, selective motor control (SMC), range of motion (ROM), and spasticity in the lower extremities of adults with cerebral palsy (CP), as well as the proximal to distal distribution of SMC impairment in lower extremity joints. [Participants and Methods] We recruited 11 adults with bilateral spastic CP, ranging from levels I to III according to the Gross Motor Function Classification System (GMFCS). We evaluated participants according to the Selective Control Assessment of the Lower Extremity (SCALE), ROM, and the Modified Ashworth Scale (MAS). We conducted the Friedman test to assess differences among the SCALE scores of each joint. The relationship between GMFCS level, SCALE scores, ROM, and MAS scores was assessed. [Results] The mean SCALE scores were lower for distal than for proximal joints. The SCALE scores of each leg showed significant inverse correlations with the GMFCS level. [Conclusion] SMC in adults with CP strongly influences gross motor function. SMC did not have a significant relationship with spasticity or ROM. SMC, ROM, and spasticity independently influenced gross motor function in adults with CP. SMC impairment in adults with CP was higher in distal than in proximal joints.

Adaptive Sliding Mode Back-Stepping Speed Control of Hydraulic Motor for Wave Energy Conversion Device

In order to improve the stability of the wave power generation device, the mechanism of variable displacement control mechanism of hydraulic motor is proposed and the control strategy of motor speed is built. The detailed mathematical representation and dynamic characteristics of motor control are analyzed; the adaptive sliding mode control method and a back-stepping control strategy are designed for the proposed controller to overcome the influence of the parameter uncertainty in the nonlinear system. The adaptive law is designed by Lyapunov criterion to ensure the stability and convergence of the whole closed-loop system. In order to verify the feasibility of the proposed control strategy, a wave power generation land experimental platform is designed, the experimental platform is mainly consists of the test bench bracket, the hydraulic transmission system and the electric power processing system. Through comparative analysis with PID control method, the advantages of this control method are described and the speed of motor can be controlled accurately.

A comparison of motor control characteristics of the dominant and non-dominant arms in response to assistive force during unilateral task

A comparison of motor control characteristics of the dominant and non-dominant arms in response to assistive force during unilateral task

2H1-5 Motor control characteristics of assisted and voluntary force release

2H1-5 Motor control characteristics of assisted and voluntary force release

The experience of spasticity after spinal cord injury: perceived characteristics and impact on daily life.

Cross-sectional survey. Determine the impact of motor control characteristics attributed to spasticity, such as spasms, stiffness, and clonus on the daily life of people with spinal cord injury (SCI). Nationwide, United States. Internet-administered questionnaire, the Patient Reported Impact of Spasticity Measure (PRISM) and items describing characteristics of spasticity including stiffness, spasms, clonus, and pain. Of the 145 respondents, 113 (78%) reported a PRISM score of at least 5/164, indicating spasticity had some impact on their daily lives. Stiffness impact was highly correlated (ρ = 0.84; p < 0.01) with the PRISM negative impact on Daily Activities subscale and moderately correlated with the other PRISM subscales (ρ = 0.55-0.63; p < 0.01). Spasm presence had a negligible or low correlation with PRISM negative impact subscales (ρ = 0.29-0.47; p < 0.01). Trunk muscle stiffness and spasms had a low correlation with PRISM Need for Assistance and Daily activities (ρ = 0.42 and ρ = 0.41, p < 0.01, respectively). Anti-spasticity medications were ineffective for 58% of respondents. Pain in the legs was reported by 57% of respondents. The experience of spasticity is highly individualized, and is often distributed differently across arms, trunk, and legs. Despite the fact that traditional definitions of spasticity focus on reflex responsiveness, the stiffness associated with spasticity appears to be more problematic than spasms or clonus. The self-described characteristics of spasticity and its physiological presentation are complex and related to pain. This varied presentation lends support to the concept that management of spasticity may be best achieved by multimodality strategies.

Motor control characteristics for circular tracking movements of human wrist

This paper investigates motor characteristics during circular tracking movements of human wrist. Ten subjects performed a visually guided target tracking task using two degrees-of-freedom wrist movements as a tracer. Based on trajectories of the tracer and the target, three control parameters in polar coordinates were considered: R error as an evaluation of the circular movement performance, theta error of the position-control precision, and omega error of the velocity-control precision. We then examined the influence of three different speeds (0.05, 0.1, and 0.2 Hz) and visibility of the target on the three parameters to observe changes in control strategy. The theta error particularly demonstrated that subjects were more dependent on position control for the lower tracking speed of 0.05 Hz with a visible target, where the highest percentage increase of 210.6% in theta errors from the target visible to the target invisible regions was reported. However, as the target speed increases, the subjects concentrated more on the velocity of the target as a main control parameter, and a minimum percentage decrease of 9.52% in the omega error appeared from target visible to target invisible regions for 0.2 Hz. The results suggest that velocity control is more dominant during target invisible or fast tracking task.

Measuring frequency and transient characteristics on Yaskawa Motor and controlling the motor by means of PC

This article familiarise its readers with possibilities of motor control, measuring frequency and transient characteristics on Yaskawa Motor in laboratory conditions using Matlab – Simulink software and its Real Time Target toolbox. Using the Real Time Target toolbox along with MF624 I/O card, we are able to capture, store and submit information on state variables of the motor in real time. The manufacturer of Yaskawa motors does not provide with information about frequency and transient characteristics of current, speed or position loops. In order to verify the mathematical model, it is necessary to measure these characteristics on a specific motor type and use the obtained results to recalculate amplification of individual controllers by means of the mathematical model. Adjusting the current controller is not possible, since the values are fixed by the manufacturer. The manufacturer allows the user of the current controller to choose from 10 pre-set values (from the „softest“ to the „most stiff“). By making the model more accurate, we may perform simulations of various load states that are approaching real ones.

Influence of motor control characteristics on load sharing behavior of torque coupling gear set

The influence of the control characteristics of a direct torque control (DTC) motor on the load sharing behavior of a torque coupling gear set is studied by establishing a dynamic model of a multi-motor torque coupling system. The effects of run-out errors of the pinions of the torque coupling gear set on the powertrain are analyzed under steady operating conditions. The difference in rotational speed among the pinions becomes apparent, and the load sharing behavior deteriorates when there are run-out errors. The relationship between the control characteristics and load sharing behavior is studied. The difference in rotational speed decreases and the load sharing behavior improves as proportional and integral gains of the speed controller increase.

Dynamic Characteristic Analysis of Spinal Motor Control Between 11- and 15-Year-Old Children.

Spinal motor control can provide substantial insight for the causes of spinal musculoskeletal disorders. Its dynamic characteristics however, have not been fully investigated. The objective of this study is to explore the dynamic characteristics of spinal motor control via the fractional Brownian motion mathematical technique. Spinal curvatures and repositioning errors of different spinal regions in 64 children age 11- or 15-years old during upright stance were measured and compared for the effects of age and gender. With the application of the fractional Brownian motion analytical technique to the changes of spinal curvatures, distinct persistent movement behaviors could be determined, which could be interpreted physiologically as open-loop behaviors. Moreover, it was found that the spinal motor control of 15-year-old children was better than that of 11-year-old children with smaller repositioning error and less curvature variability as well as shorter response time and smaller curvature deformation.

A functional tracking task to assess frontal plane motor control in post stroke gait

The ability to execute appropriate medio-lateral foot placements during gait is thought to require active frontal plane control and to be critical in maintaining upright posture during gait. The aggregate frontal plane metrics of step width and step width variability have been assessed for post-stroke populations, but only under normal walking conditions. However, in the case of stroke, limb specific differences in sensory-motor control are likely. Thus, an investigation of limb specific motor control characteristics under tracking task conditions is needed to appropriately characterize frontal plane sensory-motor control post-stroke. Chronic stroke subjects (n=15) and age matched control subjects (n=10) tracked static, bilateral foot placement targets at self-selected walking speeds and completed a free walking trial. Variability and error of tracking performance were analyzed for step width and foot placement. Stroke subjects demonstrated reduced ability to control step width variability and foot placement variability, compared to control subjects. Step width variability and affected limb foot placement variability were sensitive to task complexity, increasing significantly in response to a decrease in step width target size. These results show that stroke mediated changes in the sensory-motor integration processes are manifested as inter-limb differences in frontal plane motor variability during a gait tracking task, with an additional sensitivity to task complexity. Additionally, the proposed step width tracking paradigm presents a clinically reproducible motor control metric that can be used for diagnostic assessment or as a potential outcome for a gait training regimen.