Locomotion Circuit Research Articles

MEASUREMENT AND ANALYSIS OF THE PERFORMANCE OF THE PVP-20 SLIP DETECTION DEVICE

One of the most critical elements ensuring the proper operation of locomotives are devices that detect and eliminate slipping, especially during the start-up of the locomotive in difficult operating conditions. Various types of slip control systems and methods are used on traction vehicles, depending on the design of a given locomotive and the assumptions made related to the functionality of a given solution. This article describes the PVP-20 type slip detection device used in many older electric locomotives. A proprietary measuring system was developed, enabling it to be connected to the locomotive circuit, to perform measurements in conditions of large disturbances and high voltages prevailing on the electric locomotive. Using this measuring system, the PVP-20 device was tested under operating conditions for the ability to detect slips. It has been shown that the described device is highly insensitive. Hence, we propose our concept for solving this problem.

Cerebrospinal fluid-contacting neuron tracing reveals structural and functional connectivity for locomotion in the mouse spinal cord.

Cerebrospinal fluid-contacting neurons (CSF-cNs) are enigmatic mechano- or chemosensory cells lying along the central canal of the spinal cord. Recent studies in zebrafish larvae and lampreys have shown that CSF-cNs control postures and movements via spinal connections. However, the structures, connectivity, and functions in mammals remain largely unknown. Here we developed a method to genetically target mouse CSF-cNs that highlighted structural connections and functions. We first found that intracerebroventricular injection of adeno-associated virus with a neuron-specific promoter and Pkd2l1-Cre mice specifically labeled CSF-cNs. Single-cell labeling of 71 CSF-cNs revealed rostral axon extensions of over 1800 μm in unmyelinated bundles in the ventral funiculus and terminated on CSF-cNs to form a recurrent circuitry, which was further determined by serial electron microscopy and electrophysiology. CSF-cNs were also found to connect with axial motor neurons and premotor interneurons around the central canal and within the axon bundles. Chemogenetic CSF-cNs inactivation reduced speed and step frequency during treadmill locomotion. Our data revealed the basic structures and connections of mouse CSF-cNs to control spinal motor circuits for proper locomotion. The versatile methods developed in this study will contribute to further understanding of CSF-cN functions in mammals.

Влияние колебаний напряжения контактной сети на токовые переходные процессы в силовой цепи электровоза

The statistics of electric arc transfers along the collector of traction electric motors of the 2ES6 electric locomotive for 2020 are given. It is noted that half of the failures are associated with a potential spark on the collector, which indicates increased armature currents in the electric locomotive power circuit. The given voltage curve of the contact network also indicates that the power circuit is subject to constant current fluctuations. In the model of the power circuit of the 2ES6 electric locomotive, the mechanical component of the drive has been modified. It takes into account the resistance to train movement on one of the difficult sections of the Sverdlovsk Sabik - Sarga railway, as well as the inertia of the rotating parts of the 2ES6 electric locomotive and four-axle freight gondolas. The effect of voltage fluctuations in the contact network on current transients at different values of the maximum excitation voltage has been modelled. It is established that with the increase in the excitation voltage, the amplitudes of the armature current and the excitation current decrease, the duration of exceeding the currents of their limit value decreases. With voltage fluctuations up to 200 V, the armature current and the excitation current in the power circuit of the 2ES6 electric locomotive are in the range of their limit values with the increased value of the maximum excitation voltage of 120 V. With voltage fluctuations of more than 200 V, it is advisable to use low pass input filters.

ВЫБОР ОПТИМАЛЬНОГО ПРОТИВОДЕЙСТВУЮЩЕГО УСИЛИЯ ДЛЯ ДОСТИЖЕНИЯ МАКСИМАЛЬНОГО БЫСТРОДЕЙСТВИЯ ЭЛЕКТРОМАГНИТА

Based on the analysis of switching devices and various electrical installations, the article shows that their main element is a high-speed electromagnetic device that performs the functions of a reacting organ and a drive. Both a polarized and a neutral electromagnet can be used as such a device. So far, polarized electromagnets have been most widely used as the fastest ones. However, there are a number of designs of neutral type electromagnets that can replace polarized electromagnets, in particular in electric locomotive circuit breakers. An analysis of the state of the problem showed that the methods for calculating and studying high-speed electromagnetic devices require more rigorous and accurate mathematical calculations that allow replacing experimental studies in real emergency conditions and at the same time automating the work of researchers through the widespread use of more accurate calculations. The results of theoretical studies of processes occurring in high-speed electromagnets, mathematical dependencies for calculating parameters and characteristics, both in static and dynamic modes of operation, are presented. An equation was obtained to determine the optimal counteracting force, at which the cycle time is minimal. Mathematical algorithms have been developed for calculating the static and dynamic characteristics of high-speed electromagnets, taking into account steel saturation, leakage fluxes, eddy currents in massive elements of magnetic circuits and current conductors.

Analysis of Maintenance Measures for SS4B Electric Locomotive Main Circuit Breaker

Analysis of Maintenance Measures for SS4B Electric Locomotive Main Circuit Breaker

Combined neuromodulatory approaches in the central nervous system for treatment of spinal cord injury.

To report progress in neuromodulation following spinal cord injury (SCI) using combined brain and spinal neuromodulation.Neuromodulation refers to alterations in neuronal activity for therapeutic purposes. Beneficial effects are established in disease states such as Parkinson's Disease (PD), chronic pain, epilepsy, and SCI. The repertoire of neuromodulation and bioelectric medicine is rapidly expanding. After SCI, cohort studies have reported the benefits of epidural stimulation (ES) combined with training. Recently, we have explored combining ES with deep brain stimulation (DBS) to increase activation of descending motor systems to address limitations of ES in severe SCI. In this review, we describe the types of applied neuromodulation that could be combined in SCI to amplify efficacy to enable movement. These include ES, mesencephalic locomotor region (MLR) - DBS, noninvasive transcutaneous stimulation, transcranial magnetic stimulation, paired-pulse paradigms, and neuromodulatory drugs. We examine immediate and longer-term effects and what is known about: (1) induced neuroplastic changes, (2) potential safety concerns; (3) relevant outcome measures; (4) optimization of stimulation; (5) therapeutic limitations and prospects to overcome these. DBS of the mesencephalic locomotor region is emerging as a potential clinical target to amplify supraspinal command circuits for locomotion. Combinations of neuromodulatory methods may have additive value for restoration of function after spinal cord injury.

Modeling spinal locomotor circuits for movements in developing zebrafish.

Many spinal circuits dedicated to locomotor control have been identified in the developing zebrafish. How these circuits operate together to generate the various swimming movements during development remains to be clarified. In this study, we iteratively built models of developing zebrafish spinal circuits coupled to simplified musculoskeletal models that reproduce coiling and swimming movements. The neurons of the models were based upon morphologically or genetically identified populations in the developing zebrafish spinal cord. We simulated intact spinal circuits as well as circuits with silenced neurons or altered synaptic transmission to better understand the role of specific spinal neurons. Analysis of firing patterns and phase relationships helped to identify possible mechanisms underlying the locomotor movements of developing zebrafish. Notably, our simulations demonstrated how the site and the operation of rhythm generation could transition between coiling and swimming. The simulations also underlined the importance of contralateral excitation to multiple tail beats. They allowed us to estimate the sensitivity of spinal locomotor networks to motor command amplitude, synaptic weights, length of ascending and descending axons, and firing behavior. These models will serve as valuable tools to test and further understand the operation of spinal circuits for locomotion.

On the issue of increasing operational energy efficiency of eight-axle passenger DC electric locomotives

Mass of a passenger train and, accordingly, number of cars in its composition is selected based on the amount of passenger traffic on the section, determined by the seasonal demand for transportation in each direction. In one direction of the section serviced by an electric locomotive, the mass of a passenger train may differ several times from the opposite direction, which depends on the destination station of the train and the period of its circulation. At present, in addition to 6-axle electric locomotives of the ChS2T and EP2K series, more powerful 8-axle electric locomotives of the ChS7 series operate in the same schedule for traction of passenger trains on railway sections electrified with direct current with a voltage of 3 kV catenary. All three series of the considered electric locomotives are designed for a maximum operating speed of up to 160 km/h. In this regard, there is a situation with the underutilization of the maximum speed and excess power of the ChS7 electric ocomotives, especially when operating with passenger trains of medium and low weight and a limited speed of 120 km/h. The comparative data on the specific power consumption of the EP2K 6-axle electric locomotives and the ChS7 8-axle electric locomotives operating in the same schedule, presented in the article, indicate the need to find additional reserves for saving the specific power consumption when servicing passenger trains of medium and low weight with ChS7 electric locomotives. The electric locomotive power system includes traction and auxiliary electric machines. The article discusses ways to turn off part of traction motors, which can be carried out with a standard electric locomotive circuit. However, when one section of the electric locomotive is turned off, the power of the four traction motors remaining in operation is not always sufficient to drive a passenger train according to the schedule. Therefore, a variant of improving the power circuit of an electric locomotive in the process of carrying out its overhaul is proposed. This option represents the modernization of the power circuit of the ChS7 electric locomotive when operating on a series-parallel connection with a pair of traction motors disconnected. As a result, the power circuit of the 8-axle electric locomotive operates similarly to the circuit of 6-axle DC electric locomotives with a collector traction drive. The expected savings in specific power consumption can reach 15% in comparison with the operation of an 8-axle electric locomotive ChS7 in normal mode. Switching off one section of the electric locomotive and further running the train on four traction electric motors will reduce the specific power consumption by up to 25%.

Исследование энергетических характеристик устройства компенсации реактивной мощности с регулируемой индуктивностью в электротяговой сети на экспериментальной установке

Objective: Checking the theoretical provisions of the possibility of controlling the reactive power of an adjustable inductance compensating device. Testing and optimizing the algorithm of the reactive power regulating device. Assessing energy effi ciency of the device. Checking stability of the device in transient modes. Suggesting methods to improve stability of the system. Conducting a harmonic analysis of current and voltage curves obtained as a result of physical modeling, developing ways to suppress higher current and voltage harmonic. Methods: The scheme of the experimental setup was built, the electrical element base was selected, the measuring instruments used were determined, the experimental stand was assembled. Curves of changes in current, voltage, active and reactive power were taken on the physical model for operating modes without a compensating device, with an unregulated and adjustable compensating device. The change in current for critical transients is analyzed. To evaluate the fi ltering of higher harmonics of current and voltage by a compensating device, oscillograms were taken in operating mode with a load and after adding a diode bridge to the electric locomotive circuit, and their harmonic analysis was performed. Results: The adjustable device provides reactive power compensation in the load range of no less than 90 %. Additional measures are required to lower the active resistance of the compensating device reactor. The use of a reactor connected in series with a capacitor reduces the switching current and overvoltage in the device. The compensating device can operate in the mode of a broadband fi lter of higher harmonics. Practical importance: A physical model of an alternating current traction network with a reactive power compensating device and a controlled variable inductance has been created, which makes it possible to analyze both instantaneous and long-term processes in the traction network.

A wake-active locomotion circuit depolarizes a sleep-active neuron to switch on sleep.

Sleep-active neurons depolarize during sleep to suppress wakefulness circuits. Wake-active wake-promoting neurons in turn shut down sleep-active neurons, thus forming a bipartite flip-flop switch. However, how sleep is switched on is unclear because it is not known how wakefulness is translated into sleep-active neuron depolarization when the system is set to sleep. Using optogenetics in Caenorhabditis elegans, we solved the presynaptic circuit for depolarization of the sleep-active RIS neuron during developmentally regulated sleep, also known as lethargus. Surprisingly, we found that RIS activation requires neurons that have known roles in wakefulness and locomotion behavior. The RIM interneurons-which are active during and can induce reverse locomotion-play a complex role and can act as inhibitors of RIS when they are strongly depolarized and as activators of RIS when they are modestly depolarized. The PVC command interneurons, which are known to promote forward locomotion during wakefulness, act as major activators of RIS. The properties of these locomotion neurons are modulated during lethargus. The RIMs become less excitable. The PVCs become resistant to inhibition and have an increased capacity to activate RIS. Separate activation of neither the PVCs nor the RIMs appears to be sufficient for sleep induction; instead, our data suggest that they act in concert to activate RIS. Forward and reverse circuit activity is normally mutually exclusive. Our data suggest that RIS may be activated at the transition between forward and reverse locomotion states, perhaps when both forward (PVC) and reverse (including RIM) circuit activity overlap. While RIS is not strongly activated outside of lethargus, altered activity of the locomotion interneurons during lethargus favors strong RIS activation and thus sleep. The control of sleep-active neurons by locomotion circuits suggests that sleep control may have evolved from locomotion control. The flip-flop sleep switch in C. elegans thus requires an additional component, wake-active sleep-promoting neurons that translate wakefulness into the depolarization of a sleep-active neuron when the worm is sleepy. Wake-active sleep-promoting circuits may also be required for sleep state switching in other animals, including in mammals.

Application of a shunting discharge arm based on fully controllable semiconductor devices in an ac-wire dc-motor electric locomotive power circuit in a regenerative braking mode

Application of a shunting discharge arm based on fully controllable semiconductor devices in an ac-wire dc-motor electric locomotive power circuit in a regenerative braking mode

An Intelligent Wheelset Spinning Detection System in a Direct Current Traction Drive

A spinning detection method of a locomotive wheelset in a dc traction drive and its implementation on the basis of intelligent processing of measuring data of the drive control system is considered. An increase in the amplitudes of the low-frequency harmonics of the voltage sensor output signal on the locomotive power circuit elements is used as a sign of loss of motion stability of the wheelset due to reaching the threshold wheel–rail adhesion. For automatic multilevel identification of spinning modes, a random forest algorithm-based classifier is used. The results of the analysis of the control power circuit parameters preindicated by experts show the high sensitivity and accuracy of the proposed intelligent spinning detection system.

Acute and chronic methylphenidate administration in intact and VTA-specific and nonspecific lesioned rats.

Methylphenidate (MPD) is a psychostimulant used for the treatment of ADHD and works by increasing the bioavailability of dopamine (DA) in the brain. As a major source of DA, the ventral tegmental area (VTA) served as the principal target in this study as we aimed to understand its role in modulating the acute and chronic MPD effect. Forty-eight male Sprague-Dawley rats were divided into control, sham, electrical lesion, and 6-OHDA lesion groups. Given the VTA's implication in the locomotive circuit, three locomotor indices-horizontal activity, number of stereotypy, and total distance-were used to measure the animals' behavioral response to the drug. Baseline recording was obtained on experimental day 1 (ED 1) followed by surgery on ED 2. After recovery, the behavioral recordings were resumed on ED 8. All groups received daily intraperitoneal injections of 2.5mg/kg MPD for six days after which the animals received no treatment for 3 days. On ED 18, 2.5mg/kg MPD was re-administered to assess for the chronic effect of the psychostimulant. Except for one index, there was an increase in locomotive activity in all experimental groups after surgery (in comparison to baseline activity), acute MPD exposure, induction with six daily doses, and after MPD re-challenge. Furthermore, the increase was greatest in the electrical VTA lesion group and lowest in the 6-OHDA VTA lesion group. In conclusion, the results of this study suggest that the VTA may not be the primary nucleus of MPD action, and the VTA plays an inhibitory role in the locomotive circuit.

Challenges and Future Prospects on 3D in-vitro Modeling of the Neuromuscular Circuit.

Movement of skeletal-muscle fibers is generated by the coordinated action of several cells taking part within the locomotion circuit (motoneurons, sensory-neurons, Schwann cells, astrocytes, microglia, and muscle-cells). Failures in any part of this circuit could impede or hinder coordinated muscle movement and cause a neuromuscular disease (NMD) or determine its severity. Studying fragments of the circuit cannot provide a comprehensive and complete view of the pathological process. We trace the historic developments of studies focused on in-vitro modeling of the spinal-locomotion circuit and how bioengineered innovative technologies show advantages for an accurate mimicking of physiological conditions of spinal-locomotion circuit. New developments on compartmentalized microfluidic culture systems (cμFCS), the use of human induced pluripotent stem cells (hiPSCs) and 3D cell-cultures are analyzed. We finally address limitations of current study models and three main challenges on neuromuscular studies: (i) mimic the whole spinal-locomotion circuit including all cell-types involved and the evaluation of independent and interdependent roles of each one; (ii) mimic the neurodegenerative response of mature neurons in-vitro as it occurs in-vivo; and (iii) develop, tune, implement, and combine cμFCS, hiPSC, and 3D-culture technologies to ultimately create patient-specific complete, translational, and reliable NMD in-vitro model. Overcoming these challenges would significantly facilitate understanding the events taking place in NMDs and accelerate the process of finding new therapies.

Functionally asymmetric motor neurons contribute to coordinating locomotion of Caenorhabditis elegans.

Locomotion circuits developed in simple animals, and circuit motifs further evolved in higher animals. To understand locomotion circuit motifs, they must be characterized in many models. The nematode Caenorhabditis elegans possesses one of the best-studied circuits for undulatory movement. Yet, for 1/6th of the cholinergic motor neurons (MNs), the AS MNs, functional information is unavailable. Ventral nerve cord (VNC) MNs coordinate undulations, in small circuits of complementary neurons innervating opposing muscles. AS MNs differ, as they innervate muscles and other MNs asymmetrically, without complementary partners. We characterized AS MNs by optogenetic, behavioral and imaging analyses. They generate asymmetric muscle activation, enabling navigation, and contribute to coordination of dorso-ventral undulation as well as anterio-posterior bending wave propagation. AS MN activity correlated with forward and backward locomotion, and they functionally connect to premotor interneurons (PINs) for both locomotion regimes. Electrical feedback from AS MNs via gap junctions may affect only backward PINs.

A Real-Time Lift Detection Strategy for a Hip Exoskeleton.

Repetitive lifting of heavy loads increases the risk of back pain and even lumbar vertebral injuries to workers. Active exoskeletons can help workers lift loads by providing power assistance, and therefore reduce the moment and force applied on L5/S1 joint of human body when performing lifting tasks. However, most existing active exoskeletons for lifting assistance are unable to automatically detect user's lift movement, which limits the wide application of active exoskeletons in factories. In this paper, we propose a simple but effective lift detection strategy for exoskeleton control. This strategy uses only exoskeleton integrated sensors, without any extra sensors to capture human motion intentions. This makes the lift detection system more practical for applications in manufacturing environments. Seven healthy subjects participated in this research. Three different sessions were carried out, two for training and one for testing the algorithm. In the two training sessions, subjects were asked to wear a hip exoskeleton, controlled in transparent mode, and perform repetitive lifting and a locomotion circuit; lifting was executed with different techniques. The collected data were used to train the lift detection model. In the testing session, the exoskeleton was controlled in order to deliver torque to assist the lifting action, based on the lift detection made by the trained algorithm. The across-subject average accuracy of lift detection during online test was 97.97 ± 1.39% with subject-dependent model. Offline, the algorithm was trained with data acquired from all subjects to verify its performance for subject-independent detection, and an accuracy of 97.48 ± 1.53% was achieved. In addition, timeliness of the algorithm was quantitatively evaluated and the time delay was <160 ms across different lifting speeds. Surface electromyography was also measured to assess the efficacy of the exoskeleton in assisting subjects in performing load lifting tasks. These results validate the promise of applying the proposed lift detection strategy for exoskeleton control aiming at lift assistance.

Simulations of processes in the power circuit of VL10 (VL-10W) locomotives with traction motors connected in series

Results of simulations of the processes of changing currents and voltages in power circuits of VL10 (VL-10W) locomotives with traction motors, which are connected in series, in cold insulation have been considered. Taking the thermal state of the insulation structures of traction motors of locomotives into account is a new approach in simulations of electrical processes in power circuits. Such a differentiated approach to simulating the electrical processes in power circuits of locomotives became possible when the capacitive components of anchor and pole windings of traction motors in locomotives were studied and taken into account in the equivalent circuits, as well as their temperature dependences. In this work, the results of simulations of the processes of changing currents and voltages in power circuits of VL10 (VL-10W) locomotives during a start from rest in the case of series connection of traction motors with insulation temperature of their anchor and pole windings equal to 20°C. The results of simulations are shown as graphic time dependences of currents and voltages in the main elements of a locomotive power circuit.

Intent Recognition in a Powered Lower Limb Prosthesis Using Time History Information

New computerized and powered lower limb prostheses are being developed that enable amputees to perform multiple locomotion modes. However, current lower limb prosthesis controllers are not capable of transitioning these devices automatically and seamlessly between locomotion modes such as level-ground walking, stairs and slopes. The focus of this study was to evaluate different intent recognition interfaces, which if configured properly, may be capable of providing more natural transitions between locomotion modes. Intent recognition can be accomplished using a multitude of different signals from mechanical sensors on the prosthesis. Since these signals are non-stationary over any given stride, and gait is cyclical, time history information may improve locomotion mode recognition. The authors propose a dynamic Bayesian network classification strategy to incorporate prior sensor information over the gait cycle with current sensor information. Six transfemoral amputees performed locomotion circuits comprising level-ground walking and ascending/descending stairs and ramps using a powered knee and ankle prosthesis. Using time history reduced steady-state misclassifications by over half (p<0.01), when compared to strategies that did not use time history, without reducing intent recognition performance during transitions. These results suggest that including time history information across the gait cycle can enhance locomotion mode intent recognition performance.

Neural control for coordinated natural oscillation patterns

We consider linear mechanical systems with asymmetric stiffness matrices. The class of systems captures essential body dynamics of animal/robotic locomotion. In particular, rhythmic body movements similar to those observed in animals can be found as a properly defined natural oscillation of the linear system. The objective is to design a nonlinear feedback controller that achieves the natural oscillation as a stable limit cycle for the closed-loop system. The controller structure we employ is inspired by neuronal circuits for animal locomotion. We translate the design requirement into a multivariable harmonic balance condition, and provide characterizations of neural controllers satisfying the condition.

Regulation of locomotion and motoneuron trajectory selection and targeting by the Drosophila homolog of Olig family transcription factors

During the development of locomotion circuits it is essential that motoneurons with distinct subtype identities select the correct trajectories and target muscles. In vertebrates, the generation of motoneurons and myelinating glia depends on Olig2, one of the five Olig family bHLH transcription factors. We investigated the so far unknown function of the single Drosophila homolog Oli. Combining behavioral and genetic approaches, we demonstrate that oli is not required for gliogenesis, but plays pivotal roles in regulating larval and adult locomotion, and axon pathfinding and targeting of embryonic motoneurons. In the embryonic nervous system, Oli is primarily expressed in postmitotic progeny, and in particular, in distinct ventral motoneuron subtypes. oli mediates axonal trajectory selection of these motoneurons within the ventral nerve cord and targeting to specific muscles. Genetic interaction assays suggest that oli acts as part of a conserved transcription factor ensemble including Lim3, Islet and Hb9. Moreover, oli is expressed in postembryonic leg-innervating motoneuron lineages and required in glutamatergic neurons for walking. Finally, over-expression of vertebrate Olig2 partially rescues the walking defects of oli-deficient flies. Thus, our findings reveal a remarkably conserved role of Drosophila Oli and vertebrate family members in regulating motoneuron development, while the steps that require their function differ in detail.