Movement Kinematics Research Articles

Kinematic modeling and motion control of a parallel robotic antenna pedestal

AbstractThis paper deals with kinematic modeling and motion control of a novel antenna pedestal based on parallel robotic mechanism. Its active joints are two sliders equipped with DC motors on a circular rail. The synchronous and asynchronous motions of the two sliders enable the antenna to rotate in azimuth and pitch. In order to solve the problem of trajectory deviation caused by nonlinear friction and other uncertain disturbances, the structure of the antenna is described at the beginning, and then, the kinematic model is established based on geometry method. Then, the fuzzy PI (FPI) control system is designed based on the position feedback of the driving slider to realize the trajectory tracking of the desired curve. Finally, the parameters of the FPI controller are optimized and validated by Simulink simulation experiments. The tracking performance and the effectiveness of the control algorithm on prototype are verified by experiments of typical trajectory following control.

Kinematic motion models based vessel state estimation to support advanced ship predictors

Advanced ship predictors can generally be considered as a vital part of the decision-making process of autonomous ships in the future, where the information on vessel maneuvering behavior can be used as the source of information to estimate current vessel motions and predict future behavior precisely. As a result, the navigation safety of autonomous vessels can be improved. In this paper, vessel maneuvering behavior consists of continuous-time system states of two kinematic motion models—the Curvilinear Motion Model (CMM) and Constant Turn Rate & Acceleration (CTRA) Model. Two state estimation algorithms—the Extended Kalman Filter (EKF) and Unscented Kalman Filter (UKF) are implemented on these two models with certain modifications so that they can be compatible with discrete-time measurements. Four scenarios, created by combining different models and algorithms, are implemented using simulated ship maneuvering data from a bridge simulator. These scenarios are then verified through the proposed stability and consistency tests. The simulation results show that the EKF tends to be unstable combined with the CMM. The estimates from the other three scenarios can generally be considered more stable and consistent, unless sudden actions or variations in vessel heading occurred during the simulation. The CTRA is also proven to be more robust compared to the CMM. As a result, a suitable combination of mathematical models and estimation filters can be considered to support advanced ship predictors in future ship navigation.

Bimanual Asymmetric Coordination in a Three-Dimensional Zooming Task Based on Leap Motion: Implications for Upper Limb Rehabilitation

This paper explores the practicability of bimanual asymmetric interaction and the factors affecting it when manipulating virtual three-dimensional objects through Leap, a novel hand motion capture device. This research has the potential to aid in the rehabilitation of people with upper limb function impairments. The participants were asked to enlarge a virtual three-dimensional box device to a predefined specified scale. Three influencing factors were addressed, i.e., task difficulty, task allocation and interactive mode. The results indicate that all factors have significant effects on movement time. However, analysis of variance tests shows that there are significant effects on the error rate and spatial patterns due to task difficulty and interactive mode, while no significant effects are found for task allocation. Additionally, task allocation is observed to have significant effects on the time of each hand from zooming phase onset to peak velocity. The action of the nondominant hand is coarser than that of the dominant hand. Interestingly, the velocities of both hands synchronized as the task difficulty level increased, even though the limbs moved at quite different speeds in the initial stage. This research provides insights into how one hand coordinates with the other in terms of the temporal aspects of movement kinematics and thus can help in designing rehabilitative devices that interact with the healthy hand.

Wearable-based assessment of anticipatory postural adjustments during step initiation in patients with knee osteoarthritis.

Older adults with moderate to severe knee osteoarthritis (KOA) exhibit adaptive strategy for initiating walking, known as anticipatory postural adjustments (APAs). While video motion kinematics has been the traditional way of measuring APAs, it can be difficult to transport and install, making it impractical for medical settings. Inertial sensors have become a more popular method for evaluating APAs, but no prior research has used accelerometers to measure gait initiation in individuals with KOA. The study aimed to assess the validity and reliability of a wearable accelerometer device for measuring APAs older adults with and without KOA. 25 individuals with KOA and 10 healthy individuals underwent evaluation using a wearable commercially available accelerometer (MetamotionC) and a video motion capture system. Reflective markers were placed on the lumbar vertebra and calcaneus. Participants were asked to initiate a step, and the researchers measured the APAlatency and APAamplitude of each subject. APAlatency showed an very large to almost perfect correlation in both groups (CG:r = 0.82; p = 0.003 and KOA r = 0.98; p < 0.00001) between the instruments, while APAamplitude had a moderate to very large correlation (CG: r = 0.65; p = 0.04and KOA: r = 0.80; p < 0.00001). Overall, the measurements showed fair to high reliability for intraclass correlation for video and accelerometer variables. Significant group effect was found for both variables: APAlatency (F1, 66 = 7.3; p = 0.008) and APAamplitude (F1,66 = 9.5; p = 0.00). The wearable tri-axial accelerometer is a valid and reliable for assessing APAs during gait initiation in individuals with KOA, and this population exhibits lower APAs when initiating a step.

Decoding movement kinematics from EEG using an interpretable convolutional neural network

Continuous decoding of hand kinematics has been recently explored for the intuitive control of electroencephalography (EEG)-based Brain-Computer Interfaces (BCIs). Deep neural networks (DNNs) are emerging as powerful decoders, for their ability to automatically learn features from lightly pre-processed signals. However, DNNs for kinematics decoding lack in the interpretability of the learned features and are only used to realize within-subject decoders without testing other training approaches potentially beneficial for reducing calibration time, such as transfer learning. Here, we aim to overcome these limitations by using an interpretable convolutional neural network (ICNN) to decode 2-D hand kinematics (position and velocity) from EEG in a pursuit tracking task performed by 13 participants. The ICNN is trained using both within-subject and cross-subject strategies, and also testing the feasibility of transferring the knowledge learned on other subjects on a new one. Moreover, the network eases the interpretation of learned spectral and spatial EEG features. Our ICNN outperformed most of the other state-of-the-art decoders, showing the best trade-off between performance, size, and training time. Furthermore, transfer learning improved kinematics prediction in the low data regime. The network attributed the highest relevance for decoding to the delta-band across all subjects, and to higher frequencies (alpha, beta, low-gamma) for a cluster of them; contralateral central and parieto-occipital sites were the most relevant, reflecting the involvement of sensorimotor, visual and visuo-motor processing. The approach improved the quality of kinematics prediction from the EEG, at the same time allowing interpretation of the most relevant spectral and spatial features.

People with multiple sclerosis and unilateral peripheral vestibular loss demonstrate similar alterations in head and trunk turning kinematics compared to healthy controls

BackgroundIndividuals with peripheral vestibulopathy are known to have difficulty with volitional head turns. This leads to differences in head and body turning kinematics, compared to those without vestibular dysfunction. Multiple sclerosis (MS), a neuro-inflammatory disease affecting the central nervous system, can cause vestibular dysfunction (dizziness, unsteadiness, gaze instability). However, head and trunk turning kinematics in people with MS (PwMS) have not been assessed. Research questionWill PwMS, demonstrate head and body kinematics alterations similar to individuals with a peripheral dysfunction compared to vestibular healthy individuals? MethodsEleven individuals with a recent vestibular schwannoma resection (VSR), fourteen PwMS, and 10 healthy control (HC) participants were fitted with head and trunk worn inertial measurement units (IMUs) and performed walking and turning tasks. Head and trunk peak turning speed and amplitude were extracted. Regression models controlling for gait speed were fit per outcome with post hoc corrections applied to significant models. ResultsYaw plane head turn speed and amplitude were significantly less in the VSR group compared to HC. Pitch plane head turn amplitude was significantly smaller in PwMS compared to HC (p = 0.04), however pitch plane speed did not differ between the groups. There was no difference between PwMS and the VSR group in yaw or pitch plane speed and amplitude. Both PwMS and the VSR group turned significantly slower than HC during the 180d body turn as measured at the head and trunk (head speed model p = 0.009 and <0.001; trunk speed model p < 0.001 for both groups) however the MS and VSR groups did not differ from each other. SignificanceTurning kinematics while walking in PwMS are altered compared to HC and are similar to individuals with unilateral vestibular hypofunction. Centrally mediated vestibular dysfunction in PwMS may alter movement kinematics and should be considered during examination and treatment.

A Kinematic Analysis of Wrist and Carpal Function Using Four-Dimensional Computed Tomography Technology: A Dynamic Perspective

An emerging imaging modality, four-dimensional computed tomography, can provide dynamic evaluation of carpal motion, which allows for a better understanding of how the carpals work together to achieve range of motion. The objective of this work was to examine kinematic motion of the carpus through a flexion/extension arc of motion using four-dimensional computed tomography. A convenience sample of 20 uninjured participants underwent a four-dimensional computed tomography scanning protocol through a complete arc of flexion/extension motion. Kinematic changes in motion were quantified using helical axes motion data for each carpal. Rotation angles were compared between bones to identify differences in kinematic motion between bones. The bones within the proximal carpal row, the lunate, scaphoid, and triquetrum, rotate significantly to differing magnitudes at the ends of motion (40° of flexion and 40° of extension). The scaphoid rotates to the highest magnitude, followed by the triquetrum, and lastly, the lunate. The distal carpal row bones rotate to similar magnitudes throughout the entire range of motion. This work describes the kinematics of the carpals throughout dynamic invivo flexion and extension. This study adds to an understanding of wrist mechanics and the possible clinical implications of pathological deviation from baseline kinematics.

Kinematics of lateral tongue-pushing movement in coordination with masticatory jaw movement: An anteroposterior projection videofluorographic study

ObjectiveDuring the mastication of solid food, the tongue pushes the bolus laterally to place it onto occlusal surfaces as the jaw is opened. This movement is referred to as tongue-pushing (TP). TP has an important role in efficient chewing, but its kinematic mechanisms remain unclear. The present study quantified the kinematics of TP and its coordination with masticatory jaw movements. MethodsVideofluorography (VFG) in anteroposterior projection was recorded while 14 healthy young adults ate 6 g each of cookies and meat. Small lead markers were glued to the tongue surface (left, right, and anterior) and buccal tooth surfaces (upper molars and lower canines). The position of the tongue and lower canine markers relative to the upper occlusal plane was quantified with Cartesian coordinates, using the right upper molar as the origin. Jaw motion during chewing was divided into TP and Non-TP cycles, based on the lateral movement of the food and tongue markers. The side of the jaw that compressed food particles was defined as the working side, while the other side was termed the balancing side. Horizontal and vertical displacements of tongue and jaw markers were compared between TP and Non-TP cycles, as well as between food types. ResultsThe mediolateral displacement of all tongue markers was significantly larger in TP than in Non-TP cycles. Vertical displacement was also significantly greater in TP than in Non-TP cycles for the anterior and working side tongue markers. TP cycles occurred more frequently with meat-chewing than with cookie-chewing. ConclusionTP is accomplished by rotation and lateral movements of the tongue surface on the working side and the anterior tongue blade, along with medial movement on the balancing side. These movements produce lateral shift and rotation of the tongue surface toward the working side in concert with jaw opening. Designing exercises to improve the strength of the lateral motion and rotation of the tongue body may be useful for individuals with impaired tongue function for eating and swallowing.

IS THE RACEWALKING BIOMECHANICS SIGNIFICANTLY INFLUENCED BY COACHING?

While there is a significant number of analyses of influence of coaching and training content on performance, detailed analyses linking teaching the technique and biomechanics indicators in literature are rather scarce. The purpose of the study was to determine the differences between two groups of racewalkers in the selected variables describing their gaits. The research method consisted of measuring ground reaction forces as well as kinematics of motion recorded by video cameras and the OptoJumpNext system of 14 athletes from two distinct training groups of athletes walking at individually determined speed. To identify the differences in 9 key variables between the two groups, a two-sample unpaired T-test was performed, which was also controlled by Cohens' effect size indicator. The main finding of the study is that 5 key variables unrelated to walking speed were statistically different between the two groups, with Group A (predominantly "M"-shaped) having a lower ratio of peak ground reaction force (GRF) to GRF at 70% of the contact phase (p=0.0000), lower ratio of total GRF at the end and beginning of the interval 70% - 80% (p=0.0006), greater pelvic rotation (p=0.0056) and a more upright posture with lower forward pelvic tilt (p=0.0001) and lower backward thoracic tilt (p=0.0000). There were no significant differences between the two groups in two variables describing upper body movement i.e. arm-swing angle and thoracic rotation. Another variable (peak GRF) was also statistically different between the two group (p=0.0000), but this variable is related to the walking speed, which was not identical for the two groups. In conclusion, differences in the selected biomechanical indicators, that are trainable according to literature, may have been influenced by apparently different training approaches applied within the two groups of athletes. We suggest that, although the gait in racewalking is rather strictly defined by the rules, the above variables can and should be controlled and influenced by training to develop a smooth racewalking technique with lower peak ground reaction forces.

A High-Certainty Visual Servo Control Method for a Space Manipulator with Flexible Joints.

This paper introduces a novel high-certainty visual servo algorithm for a space manipulator with flexible joints, which consists of a kinematic motion planner and a Lyapunov dynamics model reference adaptive controller. To enhance kinematic certainty, a three-stage motion planner is proposed in Cartesian space to control the intermediate states and minimize the relative position error between the manipulator and the target. Moreover, a planner in joint space based on the fast gradient descent algorithm is proposed to optimize the joint's deviation from the centrality. To improve dynamic certainty, an adaptive control algorithm based on Lyapunov stability analysis is used to enhance the system's anti-disturbance capability. As to the basic PBVS (position-based visual servo methods) algorithm, the proposed method aims to increase the certainty of the intermediate states to avoid collision. A physical experiment is designed to validate the effectiveness of the algorithm. The experiment shows that the visual servo motion state in Cartesian space is basically consistent with the planned three-stage motion state, the average joint deviation index from the centrality is less than 40%, and the motion trajectory consistency exceeds 90% under different inertial load disturbances. Overall, this method reduces the risk of collision by enhancing the certainty of the basic PBVS algorithm.

Investigation of Motor Activity, Movement Kinematics and Forward-Backwards Gait in Children with Cerebral Palsy.

Our aim in this study was to examine relationships between the motor activity ability, sensor-based kinematics and forward-backwards gait characteristics of children with cerebral palsy (CP). In this prospective cross-sectional study we studied 40 children with CP. We used the Pediatric Motor Activity Log Revised (PMAL-R) to assess motor activity, evaluated motion kinematics (acceleration and angular velocity) with a sensor-based application, applied the Edinburgh Visual Gait Score (EVGS) and the Timed Up and Go Test (TUG) to observe gait performance, and used the Three Meter Backward Walk Test (3MBWT) to assess backward gait. We found moderately positive significant correlations (r1 = 0.416, r2 = 0.418, p < 0.05) between the chilidren's minimum angular velocity on PMAL-R motor activity frequency (how often) and quality (how well) scores, respectively. We also found moderately negative significant correlations (r1 = -0.529, r2 = -0.521, p < 0.05) between PMAL-R frequency (how often) and quality (how well) scores with TUG, respectively. There were moderately high positive correlations (r1 = 0.415, r2 = 0.726, p < 0.05) between EVGS scores and 3MBWT and TUG scores, respectively. We concluded that angular velocity ability was moderately related to children's motor activity and showed that physical performance tests (TUG and 3MBWT) could monitor gait function and upper extremity motor activity level, including both forward and backward walking tasks, in children with CP.

Development of a Chemically Driven Biomimetic Modular Artificial Muscle (BiMAM)

Human skeletal muscle is widely considered to be the most efficient actuator, leading to extensive research on developing artificial muscles. Bioinspired technologies such as soft robotics and biomimetics are used to produce artificial muscles with performance characteristics similar to those of their biological counterpart. Despite the complexity of human skeletal muscle, advanced engineering materials and unique approaches can help develop an artificial muscle that replicates its kinematic motions. Herein, biomimetic modular artificial muscle (BiMAM), which is the culmination of different design strategies, is presented, and fabrication methods aimed at developing this BiMAM. This chemically driven modular artificial muscle uses shape memory alloy coated with nanomaterials and nano‐catalysts. Herein, a high‐energy density fuel is employed to actuate this artificial muscle, enabling fast and efficient outputs. Multiple performance characteristics are determined by conducting controlled experiments. Various methods are demonstrated to control the fuel‐based valve system and the actuation of the chemically driven artificial muscle. Lastly, to evaluate its functionality, the curling movement of a robotic finger using BiMAM is demonstrated.

New Applications on the Flows of Space-like curves specified by Normal acceleration in Minkowski Space ℝ2,1

Abstract This paper investigates the kinematic motions of space-like and time-like curves specified by acceleration fields in Minkowski space ℝ2,1. Through the motion, the relationship between the acceleration fields and velocity fields is determined. In this study, we focus on studying the flows of inextensible space-like curves with a space-like principal normal vector specified by a normal acceleration that equals the curvature of the curve. Through the motion of the inextensible space-like curve with normal acceleration, we prove that the position vector of the curve satisfies a one-dimensional wave equation. We present some novel applications and visualize the flows of curves and their curvatures.

Excitatory nucleo-olivary pathway shapes cerebellar outputs for motor control

The brain generates predictive motor commands to control the spatiotemporal precision of high-velocity movements. Yet, how the brain organizes automated internal feedback to coordinate the kinematics of such fast movements is unclear. Here we unveil a unique nucleo-olivary loop in the cerebellum and its involvement in coordinating high-velocity movements. Activating the excitatory nucleo-olivary pathway induces well-timed internal feedback complex spike signals in Purkinje cells to shape cerebellar outputs. Anatomical tracing reveals extensive axonal collaterals from the excitatory nucleo-olivary neurons to downstream motor regions, supporting integration of motor output and internal feedback signals within the cerebellum. This pathway directly drives saccades and head movements with a converging direction, while curtailing their amplitude and velocity via the powerful internal feedback mechanism. Our finding challenges the long-standing dogma that the cerebellum inhibits the inferior olivary pathway and provides a new circuit mechanism for the cerebellar control of high-velocity movements.

Purkinje cell microzones mediate distinct kinematics of a single movement

The classification of neuronal subpopulations has significantly advanced, yet its relevance for behavior remains unclear. The highly organized flocculus of the cerebellum, known to fine-tune multi-axial eye movements, is an ideal substrate for the study of potential functions of neuronal subpopulations. Here, we demonstrate that its recently identified subpopulations of 9+ and 9- Purkinje cells exhibit an intermediate Aldolase C expression and electrophysiological profile, providing evidence for a graded continuum of intrinsic properties among PC subpopulations. By identifying and utilizing two Cre-lines that genetically target these floccular domains, we show with high spatial specificity that these subpopulations of Purkinje cells participate in separate micromodules with topographically organized connections. Finally, optogenetic excitation of the respective subpopulations results in movements around the same axis in space, yet with distinct kinematic profiles. These results indicate that Purkinje cell subpopulations integrate in discrete circuits and mediate particular parameters of single movements.

Development Results of a Cross-Platform Positioning System for a Robotics Feed System at a Dairy Cattle Complex

Practical experience demonstrates that the development of agriculture is following the path of automating and robotizing operational processes. The operation of feed pushing in the feeding alley is an integral part of the feeding process and significantly impacts dairy cattle productivity. The aim of this research is to develop an algorithm for automatic positioning and a mobile remote-control system for a wheeled robot on a dairy farm. The kinematic and dynamic motion characteristics of the wheeled robot were obtained using software that allows simulation of physical processes in an artificial environment. The mobile application was developed using Swift tools, with the preliminary visualization of interfaces and graphic design. The system uses technical vision based on RGB cameras and programmed color filters and is responsible for the automatic positioning of the feed-pusher robot. This system made it possible to eliminate the inductive sensors from the system and suspend the labor effort required for assembling the contour wire of the feed alley. By assessing the interaction between the mobile app and the feed pusher via the base station connected to the Internet and located on the farm, the efficiency and accuracy of the feedback was measured. Furthermore, remote changes in the operating regime of the robot (start date) were proven to be achievable, and the productiveness of the food supplement dispenser also became manageable.

Using temperature to analyze the neural basis of a time-based decision.

The basal ganglia are thought to contribute to decision-making and motor control. These functions are critically dependent on timing information, which can be extracted from the evolving state of neural populations in their main input structure, the striatum. However, it is debated whether striatal activity underlies latent, dynamic decision processes or kinematics of overt movement. Here, we measured the impact of temperature on striatal population activity and the behavior of rats, and compared the observed effects with neural activity and behavior collected in multiple versions of a temporal categorization task. Cooling caused dilation, and warming contraction, of both neural activity and patterns of judgment in time, mimicking endogenous decision-related variability in striatal activity. However, temperature did not similarly affect movement kinematics. These data provide compelling evidence that the timecourse of evolving striatal activity dictates the speed of a latent process that is used to guide choices, but not continuous motor control. More broadly, they establish temporal scaling of population activity as a likely neural basis for variability in timing behavior.

Nipple properties affect sensorimotor integration during bottle feeding in an infant pig model.

Infant feeding is a critical neurological milestone in development defined by the coordination of muscles, peripheral nerves, and brainstem nuclei. In infants, milk flow rate is often limited to improve feeding performance without treating the underlying deficiencies in the sucking and swallowing processes. Modification of the neuromotor response via sensory information from the nipple during bottle feeding is an unexplored avenue for physiology-based interventions. In this study, we assessed how differences in nipple hole size and nipple stiffness affect sucking muscle activation and subsequent movement. We fabricated four bottle nipples of varying hole size and stiffness to determine how variation in nipple properties affects the sucking behavior of infant pigs. Our results demonstrate that sensory information from the nipple affects sucking motor output. Nipple hole sizes and stiffnesses with a larger milk flow rate resulted in greater muscle activity and kinematic movement. Additionally, our results suggest that sensorimotor interventions are better directed towardmodulating tongue function rather than the mandible movementsdue to a greater response to sensory information. Understanding how sensory information influences infant feeding is instrumental in promoting effective infant feeding.

How Music Moves Us: Music-induced Emotion Influences Motor Learning

Music is an important tool for the induction and regulation of emotion. Although learning a sequential motor behaviour is essential to normal motor function, to our knowledge, the role of music-induced emotion on motor learning has not been explored. Our experiment aimed to determine whether listening to different emotional music could influence motor sequence learning. We focused on two sub-components of motor sequence learning: the acquisition of the order of the elements in the sequence (the “what”), and the ability to carry out the sequence, combining the elements in a single, skilled action (the “how”). Twenty subjects performed a motor sequence-learning task with a digitizing tablet in three different experimental sessions. In each session they executed the task while listening to three different musical pieces, eliciting fearful, pleasant, and neutral mood. Eight targets were presented in a pre-set order and subjects were asked to learn the sequence while moving. Music-induced pleasure had an impact on movement kinematics with onset time and peak velocity decreasing and movement time increasing more with respect to neutral music session. Declarative learning, verbal recall of the sequence order, was improved under emotional manipulation, but only for fear-condition. Results suggest that music-induced emotion can influence both sub-components of motor learning in a different way. Music-induced pleasure may have improved motor components of sequence learning by means of increased striatal dopamine availability whereas music-induced fear may facilitate the recruitment of attentional circuits, thus acting on declarative knowledge of the sequence order.

Improved Flexible Triboelectric Nanogenerator Based on Tile‐Nanostructure for Wireless Human Health Monitor

Triboelectric nanogenerators (TENGs) have emerged as promising candidates for integrating with flexible electronics as self‐powered systems owing to their intrinsic flexibility, biocompatibility, and miniaturization. In this study, an improved flexible TENG with a tile‐nanostructured MXene/polymethyl methacrylate (PMMA) composite electrode (MP‐TENG) is proposed for use in wireless human health monitor. The multifunctional tile‐nanostructured MXene/PMMA film, which is self‐assembled through vacuum filtration, exhibits good conductivity, excellent charge capacity, and high flexibility. Thus, the MXene/PMMA composite electrode can simultaneously function as a charge‐generating, charge‐trapping, and charge‐collecting layer. Furthermore, the charge‐trapping capacity of a tile nanostructure can be optimized on the basis of the PMMA concentration. At a mass fraction of 4% PMMA, the MP‐TENG achieves the optimal output performance, with an output voltage of 37.8 V, an output current of 1.8 μA, and transferred charge of 14.1 nC. The output power is enhanced over twofold compared with the pure MXene‐based TENG. Moreover, the MP‐TENG has sufficient power capacity and durability to power small electronic devices. Finally, a wireless human motion monitor based on the MP‐TENG is utilized to detect physiological signals in various kinematic motions. Consequently, the proposed performance‐enhanced MP‐TENG proves a considerable potential for use in health monitoring, telemedicine, and self‐powered systems.