Design and Automation of a vertical electrospinning system for manufacturing nanofibers

The objective of this research consists of the design, construction and automation of the electrospinning mechatronic system to obtain nanofibers. As a first stage, the structure of the electrospinning mechatronic system and the distribution, injection and manifold system were designed and built. In the second stage, the open-loop control system was outlined and implemented. It is made up of: control, isolation stage, and the plant. In the first element, the LabView interface and ATMega2560 microcontroller were used to manipulate the variables of the injection speed and distribution of the solution, the speed of the nanofiber collector and the height between the capillary tube and the collector, the magnitude of the temperature and humidity from the environment, also, the graphic interface was developed, the second element consists of isolating the control and power stage in addition to amplifying the command signals and enabling the correction elements, the third element receiving the signals from the power stage to perform the action and produce a change in the controlled variables in the process. With this prototype, it is intended to obtain nanofibers from different polymer solutions for use in the area of catalysis and biomaterials.

Local Trajectory Planning for Autonomous Racing Vehicles Based on the Rapidly-Exploring Random Tree Algorithm

This paper presents a local trajectory planning method based on the Rapidly-exploring Random Tree (RRT) algorithm using Dubins curves for autonomous racing vehicles. The purpose of the investigated method is the real-time computation of a trajectory that could be feasible in autonomous driving. The vehicle is considered as a three Degree-of-Freedom bicycle model and a Model Predictive Control (MPC) algorithm is implemented to control the lateral and longitudinal vehicle dynamics. The trajectory planning algorithm exploits a perception pipeline using a LiDAR sensor that is mounted onto the front wing of the racing vehicle. The MPC computes the acceleration/ deceleration command and the front wheel steering angle to follow the predicted trajectory. The trajectory and control algorithms are tested on real data acquisition performed on-board the vehicle. For validation purposes, the vehicle is driven autonomously during different maneuvers performed in the racing environment that is structured with traffic cones. The feasibility of the algorithm is evaluated in terms of error with respect to the planned trajectory, tracking velocity and maximum longitudinal acceleration. The effectiveness of the method is also evaluated with respect to command signals for the steering and acceleration actuators featured by the retained racing vehicle. The results demonstrate that the trajectory is well-tracked and the signals are compatible with the actuator constraints.

Simple and complex spike responses of mouse cerebellar Purkinje neurons to regular trains and omissions of somatosensory stimuli

Cerebellar Purkinje neurons help compute absolute subsecond timing, but how their firing is affected during repetitive sensory stimulation with consistent subsecond intervals remains unaddressed. Here, we investigated how simple and complex spikes of Purkinje cells change during regular application of air puffs (3.3 Hz for ~4 min) to the whisker pad of awake, head-fixed female mice. Complex spike responses fell into two categories: those in which firing rates increased (at ~50 ms) and then fell (complex spike elevated "CxSE" cells), and those in which firing rates decreased (at ~70 ms) and then rose (complex spike reduced "CxSR" cells). Both groups had indistinguishable rates of basal complex (~1.7 Hz) and simple (~75 Hz) spikes, and initially responded to puffs with a well-timed sensory response of a short-latency (~15 ms), transient (4 ms) suppression of simple spikes. CxSE more than CxSR cells, however, also showed a longer-latency increase in simple spike rate, previously shown to reflect motor command signals. With repeated puffs, basal simple spike rates dropped greatly in CxSR but not CxSE cells; complex spike rates remained constant, but their temporal precision rose in CxSR cells and fell in CxSE cells. Also over time, transient simple spike suppression gradually disappeared in CxSE cells, suggesting habituation, but remained stable in CxSR cells, suggesting reliable transmission of sensory stimuli. During stimulus omissions, both categories of cells showed complex spike suppression with different latencies. The data indicate two modes by which Purkinje cells transmit regular repetitive stimuli, distinguishable by their climbing fiber signals.

The Microstructure of Attentional Control in the Dorsal Attention Network

The top–down control of attention involves command signals arising chiefly in the dorsal attention network (DAN) in frontal and parietal cortex and propagating to sensory cortex to enable the selective processing of incoming stimuli based on their behavioral relevance. Consistent with this view, the DAN is active during preparatory (anticipatory) attention for relevant events and objects, which, in vision, may be defined by different stimulus attributes including their spatial location, color, motion, or form. How this network is organized to support different forms of preparatory attention to different stimulus attributes remains unclear. We propose that, within the DAN, there exist functional microstructures (patterns of activity) specific for controlling attention based on the specific information to be attended. To test this, we contrasted preparatory attention to stimulus location (spatial attention) and to stimulus color (feature attention), and used multivoxel pattern analysis to characterize the corresponding patterns of activity within the DAN. We observed different multivoxel patterns of BOLD activation within the DAN for the control of spatial attention (attending left vs. right) and feature attention (attending red vs. green). These patterns of activity for spatial and feature attentional control showed limited overlap with each other within the DAN. Our findings thus support a model in which the DAN has different functional microstructures for distinctive forms of top–down control of visual attention.

Cut wires: The Electrophysiology of Regenerated Tissue

When nerves are damaged by trauma or disease, they are still capable of firing off electrical command signals that originate from the brain. Furthermore, those damaged nerves have an innate ability to partially regenerate, so they can heal from trauma and even reinnervate new muscle targets. For an amputee who has his/her damaged nerves surgically reconstructed, the electrical signals that are generated by the reinnervated muscle tissue can be sensed and interpreted with bioelectronics to control assistive devices or robotic prostheses. No two amputees will have identical physiologies because there are many surgical options for reconstructing residual limbs, which may in turn impact how well someone can interface with a robotic prosthesis later on. In this review, we aim to investigate what the literature has to say about different pathways for peripheral nerve regeneration and how each pathway can impact the neuromuscular tissue’s final electrophysiology. This information is important because it can guide us in planning the development of future bioelectronic devices, such as prosthetic limbs or neurostimulators. Future devices will primarily have to interface with tissue that has undergone some natural regeneration process, and so we have explored and reported here what is known about the bioelectrical features of neuromuscular tissue regeneration.

Ribosome Profiling Reveals a Dichotomy Between Ribosome Occupancy of Nuclear-Encoded and Mitochondrial-Encoded OXPHOS mRNA Transcripts in a Striatal Cell Model of Huntington Disease

Huntington disease (HD) is caused by an expanded polyglutamine mutation in huntingtin (mHTT), which promotes a prominent atrophy in the striatum and subsequent psychiatric, cognitive, and choreiform movements. Multiple lines of evidence point to an association between HD and aberrant striatal mitochondrial functions. However, present knowledge about whether (or how) mitochondrial mRNA translation is differentially regulated in HD remains unclear. We have recently applied ribosome profiling (Ribo-Seq), a technique based on the high-throughput sequencing of ribosome-protected mRNA fragments, to analyze detailed snapshots of ribosome occupancy of the mitochondrial mRNA transcripts in control and HD striatal cells. Ribo-seq data revealed almost unaltered ribosome occupancy on the nuclear-encoded mitochondrial transcripts involved in oxidative phosphorylation (OXPHOS) and only a mild reduction in ribosome occupancy on a few selected transcripts (SHDA, Ndufv1, Timm23, Tomm5, and Mrps22) in HD cells. By contrast, ribosome occupancy of mitochondrially encoded OXPHOS mRNAs (mtNd-1, mtNd-2, mtNd-4, mtNd-4l, mtNd-5, mtNd-6, mt-Co1, mtCyt b, and mt-ATP8) was dramatically increased, implying widespread dichotomous effects on ribosome occupancy and OXPHOS mRNA translation in HD. Thus, mHTT may command signals that specifically regulate translation of the mitochondrial OXPHOS transcripts and influence HD pathogenesis.

Shoulder kinematics plus contextual target information enable control of multiple distal joints of a simulated prosthetic arm and hand

Background Prosthetic restoration of reach and grasp function after a trans-humeral amputation requires control of multiple distal degrees of freedom in elbow, wrist and fingers. However, such a high level of amputation reduces the amount of available myoelectric and kinematic information from the residual limb. Methods To overcome these limits, we added contextual information about the target’s location and orientation such as can now be extracted from gaze tracking by computer vision tools. For the task of picking and placing a bottle in various positions and orientations in a 3D virtual scene, we trained artificial neural networks to predict postures of an intact subject’s elbow, forearm and wrist (4 degrees of freedom) either solely from shoulder kinematics or with additional knowledge of the movement goal. Subjects then performed the same tasks in the virtual scene with distal joints predicted from the context-aware network. Results Average movement times of 1.22s were only slightly longer than the naturally controlled movements (0.82 s). When using a kinematic-only network, movement times were much longer (2.31s) and compensatory movements from trunk and shoulder were much larger. Integrating contextual information also gave rise to motor synergies closer to natural joint coordination. Conclusions Although notable challenges remain before applying the proposed control scheme to a real-world prosthesis, our study shows that adding contextual information to command signals greatly improves prediction of distal joint angles for prosthetic control.

Modeling and Networked Control of Two-rigid link Robot Arm

A networked control system (NCS) is one in which controller(s), actuator(s),and sensor(s)exchange command signals and data through a limited-bandwidth communication network that may be used by other applications, devices, and control systems. Compared to classical wired controlled systems, NCSs possess many advantages. In this paper, we propose the modeling and networked control of two-rigid link robot arm. To deal with the time delays that may occur during communication between the components of the system through the network, a model of the system was first determined, and second, PID controllers were designed based on the obtained model and using the stability region boundary locus technique. To demonstrate the validity of the proposed approach, numerical simulations were conducted using TrueTime, Simscape, SimMechanics, and Simulink with the MATLAB environment

Novel approach for electromyography-controlled prostheses based on facial action

Individuals with severe tetraplegia frequently require to control their complex assistive devices using body movement with the remaining activity above the neck. Electromyography (EMG) signals from the contractions of facial muscles enable people to produce multiple command signals by conveying information about attempted movements. In this study, a novel EMG-controlled system based on facial actions was developed. The mechanism of different facial actions was processed using an EMG control model. Four asymmetric and symmetry actions were defined to control a two-degree-of-freedom (2-DOF) prosthesis. Both indoor and outdoor experiments were conducted to validate the feasibility of EMG-controlled prostheses based on facial action. The experimental results indicated that the new paradigm presented in this paper yields high performance and efficient control for prosthesis applications.

Thai Voice-Controlled Analysis for Car Parking Assistance in System-on-Chip Architecture

This paper introduces an analysis of Thai speech recognition for controlled car parking assist in the system-on-chip architecture. The objective is to investigate the male and female voice command signals, including Thai and English words, issued by the native Thai users. Hardware and software co-design by the Xilinx VIVADO are designed on an ARM multicore processor and a reconfigurable system on a ZYBO board. The experiments for Thai and English word recognition are conducted by using the Mel-frequency cepstral coefficient approach and presented in the form of spectrograms. The comparison of a voice command via Bluetooth and a reference command stored on an SD card and the ZYBO embedded board on a miniature electric vehicle is verified with the Pearson’s correlation coefficient (PCC). The experimental results show the accuracies of the received Thai/English, male/female, and indoor/outdoor voice commands as compared with the reference voice commands in the noisy surroundings. Hence, our system can support Thai/English and male/female voice commands to perform a set of actions for maneuvering a car by the PCC.