Independent Motor Control Research Articles

Advancing Robotic Fruit Picking: Adaptive End-Effector Approach

In modern agriculture, the demand for efficient fruit picking methods is constantly increasing due to labor shortages and the need to improve productivity. Traditional fruit picking methods often rely on manual labor, which is labor-intensive, time-consuming, and prone to inconsistency. This study aims to develop a novel end effector for agricultural fruit picking robots, which improves the efficiency and accuracy of fruit picking through highly flexible and adaptive design. It can effectively handle fruits of diverse types, shapes, and hardness. By adopting a three-finger scheme and independent servo motor control, the simulated movements of human hands are realized. Shape memory alloy (SMA) and electroactive polymer (EAP) as intelligent driving materials, as well as flexible materials such as silicone, are explored to optimize the grip performance and fruit protection of the actuator. High-precision visual and tactile sensors are also integrated to support the accurate identification of fruits of different maturity. The performance of the actuator is evaluated through advanced data analysis techniques, including descriptive statistics, hypothesis testing and regression analysis. The findings suggest that the proposed design optimization measures based on data analysis results can further enhance the adaptability and efficiency of the robot in future applications, thereby addressing the challenges faced in modern agricultural practices and contributing to increased productivity and sustainability in the agriculture sector.

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.

Neurophysiology of spontaneous facial expressions: II. Motor control of the right and left face is partially independent in adults

Facial expressions are described traditionally as monolithic or unitary entities. However, humans have the capacity to produce facial blends of emotion in which the upper and lower face simultaneously display different expressions. Recent neuroanatomical studies in monkeys have demonstrated that there are separate cortical motor areas for controlling the upper and lower face in each hemisphere that, presumably, also occur in humans. Using high-speed videography, we began measuring the movement dynamics of spontaneous facial expressions, including facial blends, to develop a more complete understanding of the neurophysiology underlying facial expressions. In our part 1 publication in Cortex (2016), we found that hemispheric motor control of the upper and lower face is overwhelmingly independent; 242 (99%) of the expressions were classified as demonstrating independent hemispheric motor control whereas only 3 (1%) were classified as demonstrating dependent hemispheric motor control. In this companion paper (part 2), 251 unitary facial expressions that occurred on either the upper or lower face were analyzed. 164 (65%) expressions demonstrated dependent hemispheric motor control whereas 87 (35%) expressions demonstrated independent or dual hemispheric motor control, indicating that some expressions represent facial blends of emotion that occur across the vertical facial axis. These findings also support the concepts that 1) spontaneous facial expressions are organized predominantly across the horizontal facial axis and secondarily across the vertical facial axis and 2) facial expressions are complex, multi-component, motoric events. Based on the Emotion-type hypothesis of cerebral lateralization, we propose that facial expressions modulated by a primary-emotional response to an environmental event are initiated by the right hemisphere on the left side of the face whereas facial expressions modulated by a social-emotional response to an environmental event are initiated by the left hemisphere on the right side of the face.

Hand preferences in two unimanual and two bimanual coordinated tasks in the black-handed spider monkey (Ateles geoffroyi).

Spider monkeys are interesting to study with regard to hand preferences, as they are one of the few primate species that lack a thumb and, thus, are unable to perform a precision grip. Further, being platyrrhine primates, they also largely lack independent motor control of the digits and, thus, have only limited manual dexterity. It was therefore the aim of the present study to assess hand preferences in black-handed spider monkeys (Ateles geoffroyi) in 4 tasks differing in task demand: simple unimanual reaching for food and 3 versions of the widely used tube task, including 2 bimanual versions that differ from each other in the degree of fine motor control needed and a unimanual version that does not require coordinated action of the hands. We found that black-handed spider monkeys display significant hand preferences at the individual, but not at the population, level. This was true both in the 2 bimanual coordinated tasks and in the 2 unimanual tasks. Further, our results show that the majority of animals were consistent in the hand they preferred in these 4 tasks. Our findings only partially support the notion that task demand positively correlates with strength of hand preference. Finally, we found that the index finger was the most frequently used digit in all 3 tube tasks, although the animals also used other digits and 2- and 3-finger combinations to extract food from a tube. We conclude that limited manual dexterity does not prevent spider monkeys from displaying strong and consistent hand preferences at the individual level. (PsycINFO Database Record

Robust Clamping Force Control of an Electro-Mechanical Brake System for Application to Commercial City Buses

This paper proposes a sensor-less robust force control method for improving the control performance of an electro-mechanical brake (EMB) which is applicable to commercial city buses. The EMB generates the accurate clamping force commanded by a driver through an independent motor control at each wheel instead of using existing mechanical components. In general, an EMB undergoes parameter variation and a backdrivability problem. For this reason, the cascade control strategy (e.g., force-position cascade control structure) is proposed and the disturbance observer is employed to enhance control robustness against model variations. Additionally, this paper proposed the clamping force estimation method for a sensor-less control, i.e., the clamping force observer (CFO). Finally, in order to confirm the performance and effectiveness of a proposed robust control method, several experiments are performed and analyzed.

Neurophysiology of spontaneous facial expressions: I. Motor control of the upper and lower face is behaviorally independent in adults

Facial expressions are described traditionally as monolithic entities. However, humans have the capacity to produce facial blends, in which the upper and lower face simultaneously display different emotional expressions. This, in turn, has led to the Component Theory of facial expressions. Recent neuroanatomical studies in monkeys have demonstrated that there are separate cortical motor areas for controlling the upper and lower face that, presumably, also occur in humans. The lower face is represented on the posterior ventrolateral surface of the frontal lobes in the primary motor and premotor cortices and the upper face is represented on the medial surface of the posterior frontal lobes in the supplementary motor and anterior cingulate cortices. Our laboratory has been engaged in a series of studies exploring the perception and production of facial blends. Using high-speed videography, we began measuring the temporal aspects of facial expressions to develop a more complete understanding of the neurophysiology underlying facial expressions and facial blends. The goal of the research presented here was to determine if spontaneous facial expressions in adults are predominantly monolithic or exhibit independent motor control of the upper and lower face. We found that spontaneous facial expressions are very complex and that the motor control of the upper and lower face is overwhelmingly independent, thus robustly supporting the Component Theory of facial expressions. Seemingly monolithic expressions, be they full facial or facial blends, are most likely the result of a timing coincident rather than a synchronous coordination between the ventrolateral and medial cortical motor areas responsible for controlling the lower and upper face, respectively. In addition, we found evidence that the right and left face may also exhibit independent motor control, thus supporting the concept that spontaneous facial expressions are organized predominantly across the horizontal facial axis and secondarily across the vertical axis.

2A2-N08 Modular Quadruped Control and Simulation Platform

A low complexity and low cost modular quadruped platform is proposed for simulation, control, and experimentation. The modular design is possible due to the use of digitally configurable smart servomotors. A simulation integrated modular software framework used in conjunction with the hardware platform to provide online and offline control, simulation, and optimization. The framework is split into independent platform control, motor control, communications, and simulation modules that are tightly interconnected despite a high level of abstraction. Data control mechanisms are implemented to maintain time wise synchronization while allowing independent update rates.

Implementation of Space Vector Two-Arm Modulation for Independent Motor Control Drive Fed by a Five-Leg Inverter

This paper presents the implementation of two-arm modulation (TAM) technique for the independent control of a two-induction motor drive fed by a five-leg inverter (FLI). A carrier-based space vector pulse width modulation technique for TAM is proposed to generate switching signals for FLI. Two independent three-phase space vector modulators are utilized to control two motors. The motor drive system applies two separate indirect field-oriented control methods. The stationary voltage outputs from the vector control are synthesized in the three-phase space vector modulator to generate switching signals for FLI. The performance of the independent control of the motors and the voltage utilization factor are likewise analyzed. Simulation and experimental results verify the effectiveness of the proposed method for the independent control of the two-motor drive system. The proposed technique is successfully validated by dSPACE DS1103 experimental work.

Selective chromatid segregation mechanism invoked for the human congenital mirror hand movement disorder development by RAD51 mutations: a hypothesis.

The vertebrate body plan externally is largely symmetrical across the midline but internal organs develop asymmetrically. The biological basis of asymmetric organ development has been investigated extensively for years, although the proposed mechanisms remain controversial. By comparison, the biological origin of external organs symmetry has not been extensively investigated. Bimanual hand control is one such external organs symmetry allowing independent motor control movements of both hands to a person. This gap in our knowledge is illustrated by the recent reports of heterozygous rad51 mutations causing mysterious symptoms of congenital mirror hand movement disorder (MM) in humans with 50% penetrance by an unknown mechanism. The analysis of mutations that vary symmetry or asymmetry could be exploited to decipher the mechanisms of laterality development. Here I present a hypothesis for explaining 50% penetrance of the rad51 mutation. The MM's origin is explained with the Somatic Strand-specific Imprinting and selective sister chromatid Segregation (SSIS) hypothesis proposed originally as the mechanism of asymmetric cell division to promote visceral organs body plan laterality development in vertebrates. By hypothesis, random sister chromatid segregation in mitosis occurs for a specific chromosome due to rad51/RAD51 constitution causing MM disorder development in 50% of subjects.

Transfer of the Pronator Quadratus Motor Branch for Wrist Extension Reconstruction in Brachial Plexus Palsy

In extended upper-type lesions of the brachial plexus, nerve transfers and root grafting have improved the results of shoulder and elbow reconstruction. However, wrist extension reconstruction has received little attention. In 20 cadaveric upper limbs, we dissected the anterior interosseous nerve and extensor carpi radialis brevis motor branch. Four patients with upper-type lesions of the brachial plexus with paralysis of wrist and finger extension were operated on within 10 months of trauma and followed up for 12 months after surgery. The terminal division of the anterior interosseous nerve, which innervates the pronator quadratus muscle, was transferred to the extensor carpi radialis brevis, and the distal stump was connected to a motor fascicle of the median nerve (n = 2) or to the distal branch of the flexor superficialis of the index finger (n = 2). The anterior interosseous nerve and extensor carpi radialis brevis had similar diameters (roughly 1 mm). The number of myelinated fibers in the nerve averaged 670, whereas the number in the extensor carpi radialis brevis averaged 183. The length of the nerve was approximately 80 mm, allowing for direct transfer to the extensor carpi radialis brevis with redundant length. At last evaluation, pronation scored M4 according to the Medical Research Council grading system. All patients recovered active wrist extension, scoring M4 with full, independent motor control. In C5 to C8 root injuries of the brachial plexus, transfer of the motor branch of the pronator quadratus to the extensor carpi radialis brevis can restore active wrist extension, and pronation is preserved. : Therapeutic, IV.

Padrões iniciais na aquisição do sistema de sons do português: características universais e específicas

Adopting a strictly motor approach to linguistic organization, the theoretical proposal called Molde e Conteúdo (Davies & Macneilage 1995; Macneilage & Davies 1966) argues that the first child production akin to adult speech – canonical babbling – can be seen as a motor correlate of the molde silábico. Moldes constitute a rhythmic basis catalyzing specific syllabic or segmental sequences. The independent motor control of such elements emerges gradually from jaw/tongue synergies with which the child initiates a type of vocal production similar to the adult’s. In the acquisition of speech production skills, then, changes in the quality of sounds in an utterance are initially based in changes in the amplitude of the jaw opening/closing cycle, i.e., they determine intra-syllabic organization. Syllables sequences, in turn, comprise vocalic and consonantal qualities produced in homorganic articulation places (i.e. front consonants with front vowels; back consonants with back vowels), as demonstrated child data derived from six different linguistic communities – English, Swedish, French, Japanese (in the Stanford database), Brazilian Portuguese (Teixeira & Davies 1999) e Equatorial Quichua (Gildersleeve-Neumann, doctoral dissertation in preparation, U. Texas, Austin). In general, the data on Brazilian Portuguese acquisition are comparable to production universal patterns reported for children in different languages, but also show specific characteristics due to the ambient language pressure.

Peripheral Vocal Mechanisms in Birds: Are Songbirds Special?

This paper reviews recent advances regarding the peripheral mechanisms for song production by oscine songbirds and compares the vocal mechanisms of songbirds with those of certain non-oscines. The tracheobronchial syrinx of songbirds has several pairs of intrinsic muscles specialized for controlling particular aspects of sound production. The syringeal and vocal tract anatomy of non-oscines is much more diverse than that of songbirds and has fewer or no intrinsic syringeal muscles. Often the same extrinsic tracheal muscles control both the temporal and spectral properties of vocalizations. Although the vocalizations and vocal anatomy of these two groups are quite different, a number of motor patterns important in oscine song are also used by non-oscines. These include special respiratory techniques, such as minibreaths and pulsatile expiration, for sustained rapid vocalization, as well as the ability to simultaneously produce two acoustically unrelated 'voices'. However, the complex syringeal musculature of songbirds with laterally independent motor control of each side of the syrinx provides a more versatile vocal system in which the left and right sound sources can be coordinated in different ways, by specialized song control nuclei capable of vocal learning, to achieve diverse vocal effects.

The neuromuscular control of birdsong.

Birdsong requires complex learned motor skills involving the coordination of respiratory, vocal organ and craniomandibular muscle groups. Recent studies have added to our understanding of how these vocal subsystems function and interact during song production. The respiratory rhythm determines the temporal pattern of song. Sound is produced during expiration and each syllable is typically followed by a small inspiration, except at the highest syllable repetition rates when a pattern of pulsatile expiration is used. Both expiration and inspiration are active processes. The oscine vocal organ, the syrinx, contains two separate sound sources at the cranial end of each bronchus, each with independent motor control. Dorsal syringeal muscles regulate the timing of phonation by adducting the sound-generating labia into the air stream. Ventral syringeal muscles have an important role in determining the fundamental frequency of the sound. Different species use the two sides of their vocal organ in different ways to achieve the particular acoustic properties of their song. Reversible paralysis of the vocal organ during song learning in young birds reveals that motor practice is particularly important in late plastic song around the time of song crystallization in order for normal adult song to develop. Even in adult crystallized song, expiratory muscles use sensory feedback to make compensatory adjustments to perturbations of respiratory pressure. The stereotyped beak movements that accompany song appear to have a role in suppressing harmonics, particularly at low frequencies.

Organization of corticofugal neurones in somatosensory area II of the cat.

1. This investigation had two main objectives: first to determine whether or not motor activity could be elicited by localized intracortical stimulation in somatosensory area II of the cat, and secondly to identify, by antidromic stimulation, neurones which projected to subcortical structures and to study their afferent input.2. Although arm movements could be elicited in most cats by intracortical train stimulation with tungsten micro-electrodes, the lowest motor thresholds were much higher than the lowest thresholds for the primary motor area under similar experimental conditions. Facial responses were evoked at lower stimulus thresholds, but the threshold decreased steadily as successive stimulation tracks approached the coronal face area. Previously observed responses to prolonged surface stimulation could have been caused by intracortical spread of excitation or by escape of stimulus to the primary area, especially the face area.3. Neurones with corticofugal axons projecting to bulbar and spinal levels were first identified by their antidromic response to stimulation of the cerebral peduncle. Each was further tested by stimulation of the cervical corticospinal tract, and the dorsal column nuclei. Their receptive fields were then recorded.4. It was possible to classify the neurones into four main categories: (i) non-descending neurones: neurones not activated antidromically by any of the subcortical stimulating electrodes. The majority of these neurones had very small (lemniscal type) receptive fields, (ii) corticobulbar neurones: these were invaded antidromically by stimulation of the peduncle but not by spinal or dorsal column nuclei stimulation. They had ;stocking-like' or larger receptive fields; (iii) cortico-spinal neurones: neurones driven antidromically by stimulation of corticospinal fibres. Characteristically, these neurones had large confluent fields, often bilateral. Very few had receptive fields of the lemniscal type; (iv) neurones invaded by dorsal column nuclei stimulation: the number of such units was extremely low and their receptive fields were large or ;stocking-like'.5. The results indicate that somatosensory area II in the cat does not exert an independent motor control of spinal neurones, and it is thought that corticofugal neurones of SII are involved in the control of somatosensory transmission rather than having a direct motor function.