Directional Steering Research Articles

Deployable Tubular Mechanisms Integrated with Magnetic Anchoring and Guidance System

Deployable mechanism has received more attention in the medical field due to its simple structure, dexterity, and flexibility. Meanwhile, the advantages of the Magnetic Anchoring and Guidance System (MAGS) are further highlighted by the fact that the operators can remotely control the corresponding active and passive magnetic parts in vivo. Additionally, MAGS allows the untethered manipulation of intracorporeal devices. However, the conventional instruments in MAGS are normally rigid, compact, and less flexible. Therefore, to solve this problem, four novel deployable tubular mechanisms, Design 1 (Omega-shape mechanism), Design 2 (Fulcrum-shape mechanism), Design 3 (Archway-shape mechanism), and Design 4 (Scissor-shape mechanism) in this paper, are proposed integrated with MAGS to realize the laser steering capability. Firstly, this paper introduces the motion mechanism of the four designs and analyzes the motion characterization of each structure through simulation studies. Further, the prototypes of four designs are fabricated using tubular structures with embedded magnets. The actuation success rate, the workspace characterization, the force generation and the load capability of four mechanisms are tested and analyzed based on experiments. Then, the demonstration of direct laser steering via macro setup shows that the four mechanisms can realize the laser steering capability within the error of 0.6 cm. Finally, the feasibility of indirect laser steering via a macro-mini setup is proven. Therefore, such exploration demonstrates that the application of the deployable tubular mechanisms integrated with MAGS towards in vivo treatment is promising.

Miniaturized Beam Reconfigurable Reflectarray Antenna With Wide 3-D Beam Coverage

A miniaturized electrical beam-scanning reflectarray antenna providing a directional beam and wide steering ranges with fixed <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\theta $ </tex-math></inline-formula> -polarization is proposed. To accomplish these properties, we devise a new active reflectarray cell that can control both the phase and polarization of incident waves. Accordingly, we can enforce all reflected waves to constructively interfere with each other in all target directions. To feed the proposed reflectarray cells, an omnidirectional monopole antenna is installed at the center of the reflectarray, which illuminates the reflectarray evenly. In addition, because the monopole feeder is directly connected to the reflectarray, we can significantly reduce the overall volume of the antenna down to about <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$0.5~\lambda ^{3}$ </tex-math></inline-formula> with a small F/D ratio of 0.147. Consequently, the proposed antenna attains a wide scan coverage and directional beam patterns. Moreover, the antenna can also maintain polarization direction stably, which is strongly required for dynamically moving platforms such as drones and unmanned aerial vehicles (UAVs). The experimental results agree well with the predictions, proving the validity of our approach.

Current-dependent ocular tilt reaction in deep brain stimulation of the subthalamic nucleus: Evidence for an incerto-interstitial pathway?

The aim was to characterize a combined vestibular, ocular motor and postural syndrome induced by deep brain stimulation (DBS) of the subthalamic nucleus in a patient with Parkinson's disease. In a systematic DBS programming session, eye, head and trunk position in roll and pitch plane were documented as a function of stimulation amplitude and field direction. Repeat ocular coherence tomography was used to estimate ocular torsion. The interstitial nucleus of Cajal (INC), zona incerta (ZI) and ascending vestibular fibre tracts were segmented on magnetic resonance imaging using both individual and normative structural connectomic data. Thresholded symptom-associated volumes of tissue activated (VTA) were calculated based on documented stimulation parameters. Ipsilateral ocular tilt reaction and body lateropulsion as well as contralateral torsional nystagmus were elicited by the right electrode in a current-dependent manner and subsided after DBS deactivation. With increasing currents, binocular tonic upgaze and body retropulsion were observed. Symptoms were consistent with an irritative effect on the INC. Symptom-associated VTA was found to overlap with the dorsal ZI and the ipsilateral vestibulothalamic tract, while lying rather distant to the INC proper. A ZI-to-INC 'incerto-interstitial' tract with contact to the medial-uppermost portion of the VTA could be traced. Unilateral stimulation of INC-related circuitry induces an ipsilateral vestibular, ocular motor and postural roll-plane syndrome, which converts into a pitch-plane syndrome when functional activation expands bilaterally. In this case, tractography points to an incerto-interstitial pathway, a tract previously only characterized in non-human primates. Directional current steering proved useful in managing this rare side effect.

Higher-order figure-8 microphones/hydrophones collocated as a perpendicular triad-Their "spatial-matched-filter" beam steering.

Directional sensors, if collocated but perpendicularly oriented among themselves, would facilitate signal processing to uncouple the azimuth-polar direction from the time-frequency dimension-in addition to the physical advantage of spatial compactness. One such acoustical sensing unit is the well-known "tri-axial velocity sensor" (also known as the "gradient sensor," the "velocity-sensor triad," the "acoustic vector sensor," and the "vector hydrophone"), which comprises three identical figure-8 sensors of the first directivity-order, collocated spatially but oriented perpendicularly of each other. The directivity of the figure-8 sensors is hypothetically raised to a higher order in this analytical investigation with an innocent hope to sharpen the overall triad's directionality and steerability. Against this wishful aspiration, this paper rigorously analyzes how the directivity-order would affect the triad's "spatial-matched-filter" beam's directional steering capability, revealing which directivity-order(s) would allow the beam-pattern of full maneuverability toward any azimuthal direction and which directivity-order(s) cannot.

Liquid directional steering

Liquid directional steering is not only rich in physical implications but also important for practical applications. Recently, in Science, Feng and coworkers designed and manufactured a 3D functional surface revealing that liquid directional steering can be controlled by both surface characteristics and liquid properties. Here, the significant and inspiring advances of the 3D functional surface for intelligent liquid control are highlighted, alongside remaining challenges and future directions. Liquid directional steering is not only rich in physical implications but also important for practical applications. Recently, in Science, Feng and coworkers designed and manufactured a 3D functional surface revealing that liquid directional steering can be controlled by both surface characteristics and liquid properties. Here, the significant and inspiring advances of the 3D functional surface for intelligent liquid control are highlighted, alongside remaining challenges and future directions.

Development of Microrobot for Fabricating Curved Holes by Means of Electrical Discharge Machining

One of aims in our laboratory is to develop a curved hole electrical discharge machining (EDM) system by means of a microrobot. Three units constitutes the microrobot, i.e., autonomous EDM unit, machining direction steering unit, and in-pipe self-mobile unit. These units have been developed separately in our previous studies. These respective studies have developed the autonomous EDM unit which employs shape memory alloy (SMA) as its actuator and the machining direction steering unit which consists of a helical compression spring and wires whose respective posture and feeds are controlled by linear actuators. So, this study has developed the device combining these two units which makes the device fabricate a curved hole. The experiment result shows that the developed device has the ability to fabricate a curved hole.

Three-dimensional capillary ratchet-induced liquid directional steering

Surfaces directing fluid flows Although surfaces can be made to attract or repel liquids using coatings, surface textures with specific curvature can also be used to achieve the same effect. However, fluid transport is usually limited by the specific pattern that only drives flow at the surface itself. Feng et al . created a dual-reentrant surface that has an asymmetric profile so that fluids spread out at the surface and subsurface layers. Furthermore, these surfaces can be designed so that different liquids will naturally steer in opposing directions simply because of their specific interactions with the surface. —MSL

Electric Directional Steering of Cathodoluminescence From Graphene-Based Hybrid Nanostructures

Controlling directional emission of nanophotonic radiation sources is fundamental to tailor radiation-matter interaction and to conceive highly efficient nanophotonic devices for on-chip wireless communication and information processing. Nanoantennas coupled to quantum emitters have proven to be very efficient radiation routers, while electrical control of unidirectional emission has been achieved through inelastic tunneling of electrons. Here we prove that the radiation emitted from the interaction of a high-energy electron beam with a graphene-nanoparticle composite has beaming directions which can be made to continuously span the full circle even through small variations of the graphene Fermi energy. Emission directionality stems from the interference between the double cone shaped electron transition radiation and the nanoparticle dipolar diffraction radiation. Tunability is enabled since the interference is ruled by the nanoparticle dipole moment whose amplitude and phase are driven by the hybrid plasmonic resonances of the composite and the absolute phase of the graphene plasmonic polariton launched by the electron, respectively. The flexibility of our method provides a way to exploit graphene plasmon physics to conceive improved nanosources with ultrafast reconfigurable radiation patterns.

Integrated control of vehicle stability by nonlinear observer-based exponential-like sliding mode neural network system

Dynamic stability is critical to achieve the safety of the cars, particularly during emergency maneuvers. Coordinated control algorithms are suggestive of the enhanced safety and stability of a vehicle. Hence, a novel adaptive robust multi-input control framework is developed using the combination of direct yaw moment (DYC) and active front steering (AFS). The dynamics of the steering system mechanism is included for the reliability of the proposed control scheme. The proposed controller is developed according to the approximation capacity of the radial basis function (RBF) neural network system. The adaptation laws are derived based on the Lyapunov stability theory. Additionally, the proposed integrated control paradigm contains a state observer and the sliding surface of the tracking errors converges to the asymptotic stability condition through the design of a smooth exponential reaching law. The effectiveness of the proposed control scheme is compared to a high-performance optimal robust control technique and open-loop system. In order to assess the robustness of the proposed algorithm, structured and unstructured uncertainties were also incorporated in terms of the parametric uncertainties such as the tire cornering stiffness and cross-wind gust disturbance. The results obtained for different maneuvers reveal that the proposed controller is successful to improve the handling performance and to ensure the stability of the vehicle when compared to the previously reported methods.

Computationally Assisted Design and Selection of Maneuverable Biological Walking Machines

Biohybrid Walkers In article number 2000237, Rashid Bashir, Mattia Gazzola, and co-workers present a maneuverable dual-ring biohybrid walker designed and selected through a systematic approach based on modeling, simulation, and fabrication. This dual-ring biobot consists of two tissue-engineered muscle ring actuators and a 3D-printed four-legged scaffold asymmetric in the fore/aft direction. The integration of two independent muscles on a flexible body, combined with external electrical stimulation, provides the dual-ring biobot with directional walking and rotational steering abilities.

Multi-Tier Heterogeneous Beam Management for Future Indoor FSO Networks

To meet the growing demand for wireless capacity, communications in the Terahertz (THz) and optical bands are being broadly explored. Communications within these bands provide massive bandwidth potential along with highly directional beam steering capabilities. While the available bandwidth offers incredible link capacity, the directionality of these technologies offers an even more significant potential for spatial capacity or area spectral efficiency. However, this directionality also implies a challenge related to the network’s ability to quickly establish a connection. In this paper, we introduce a multi-tier heterogeneous (MTH) beamform management strategy that utilizes various wireless technologies in order to quickly acquire a highly directional indoor free space optical communication (FSO) link. The multi-tier design offers the high resolution of indoor FSO while the millimeter-wave (mmWave) system narrows the FSO search space. By narrowing the search space, the system relaxes the requirements of the FSO network in order to assure a practical search time. This paper introduces the necessary components of the proposed beam management strategy and provides a foundational analysis framework to demonstrate the relative impact of coverage, resolution, and steering velocity across tiers. Furthermore, an optimization analysis is used to define the top tier resolution that minimizes worst-case search time as a function of lower tier resolution and top tier range.

Enhancement of asymmetric steering via interference effects induced by twofold modulations in a cavity optomechanical system

In a general two-mode cavity optomechanical system driven with a mildly amplitude modulated light field, we investigate in detail the properties of entanglement and asymmetric steering between the cavity field and the mechanical oscillator, whose frequency is also applied by a sinusoidal modulation. Twofold modulations of the system inducing interference effects determined by the relative phase between the two modulations. By calculating the logarithmic negativity and quantum steering of the two modes, we show that, different choices of the modulation intensity and the relative phase between the two physical interaction paths can either enhance or cancel the desired quantum effects, two modes can be prepared into an entangled steady state with asymmetric and directional steering. Meanwhile, the effects of interference on entanglement and asymmetric steering are also compared. The results show that the optimal relative phase between the two physical interaction paths are not the same for entanglement and asymmetric steering, opening new perspectives to understand them.

Vehicle lateral motion control via robust delay-dependent Takagi-Sugeno strategy

Presented in this research paper is an integrated direct yaw moment control (DYC) and active front steering (AFS) for an uncertain vehicle lateral dynamics model considering network-induced communication delay, which is a time-varying continuous function with a known upper bound. Firstly, we consider tire cornering stiffness as a non-linear norm-bounded uncertain system that is modeled by fuzzy membership functions, and then vehicle lateral dynamics model is expressed by a set of linear Takagi-Sugeno (T-S) uncertain fuzzy models. Secondly, since the network-induced communication delay in vehicle control system is an inherent reason for stability and performance degradation, we derive a robust delay-dependent [Formula: see text] control methodology via the Lyapunov-Krasovskii functional for stability and performance conditions of the closed-loop system. For the synthesis, the robust control method is employed within the T-S fuzzy-model-based analysis framework and formulations are performed based on the solution of delay-dependent linear matrix inequalities (LMIs). The simulation study is presented using MATLAB/Simulink to show the achieved improvements in tracking variables via the designed robust fuzzy [Formula: see text] state-feedback controller. The proposed fuzzy robust delay-dependent controller is compared with a linear robust delay-dependent controller to clearly show the tracking improvements for different road conditions. Moreover, a performance-based analysis is carried out to demonstrate the advantage of the design with respect to different delay values. It is confirmed from the analysis results that the proposed fuzzy controller can successfully stabilize and possess improved tracking performance for vehicle lateral motion control.

Managing driving disturbances in lateral vehicle dynamics via adaptive integrated chassis control

This paper presents a vehicle stability control method based on a multi-input multi-output (MIMO) model reference adaptive control (MRAC) strategy as an advanced driver assistance system (ADAS) to enhance the handling and yaw stability of the vehicle lateral dynamics. The corrective yaw moment and additive steering angle are generated using direct yaw moment control (DYC) and active front steering (AFS) at the upper control level in the hierarchical control algorithm. A nonlinear term is added to the conventional adaptive control laws to handle parametric uncertainties and disturbances. The desired yaw moment generated by the upper-level controller is converted to the brake forces and is distributed to the rear wheels by an optimal procedure at the lower-level. The major contribution of this study is the introduction of a nonlinear integrated adaptive control method based on a constraint optimization algorithm. To verify the effectiveness of the proposed control strategy, the nonlinear integrated adaptive controller, and linear time-varying MRAC are designed and used for comparison. Simulation results are performed for the J-turn and double lane change (DLC) manoeuvres at high speeds and low tyre-road friction coefficients. The desired performance of the proposed controller exhibited significant improvement compared to the conventional MRAC in terms of yaw rate tracking and handling of sideslip limitation.

Potentials and Limitations of Directional Deep Brain Stimulation: A Simulation Approach

Background: Directional leads are increasingly used in deep brain stimulation. They allow shaping the electrical field in the axial plane. These new possibilities increase the complexity of programming. Thus, optimized programming approaches are needed to assist clinical testing and to obtain full clinical benefit. Objectives: This simulation study investigates to what extent the electrical field can be shaped by directional steering to compensate for lead malposition. Method: Binary volumes of tissue activated (VTA) were simulated, by using a finite element method approach, for different amplitude distributions on the three directional electrodes. VTAs were shifted from 0 to 2 mm at different shift angles with respect to the lead orientation, to determine the best compensation of a target volume. Results: Malpositions of 1 mm can be compensated with the highest gain of overlap with directional leads. For larger shifts, an improvement of overlap of 10–30% is possible, depending on the stimulation amplitude and shift angle of the lead. Lead orientation and shift determine the amplitude distribution of the electrodes. Conclusion: To get full benefit from directional leads, both the shift angle as well as the shift to target volume are required to choose the correct amplitude distribution on the electrodes. Current directional leads have limitations when compensating malpositions >1 mm; however, they still outperform conventional leads in reducing overstimulation. Further, their main advantage probably lies in the reduction of side effects. Databases like the one from this simulation could serve for optimized lead programming algorithms in the future.

Real world clinical outcomes using a novel directional lead from a multicenter registry of deep brain stimulation for Parkinson's Disease

Objective: Deep Brain Stimulation (DBS) systems have historically used ring-shaped electrodes that produce stimulation fields with limited control over field shape and volume of tissue activated. Directional current steering may permit a more personalized DBS approach with respect to individualized shape and pattern of electrical field and corresponding volume of tissue activated. In this report, initial real-world outcomes using a directional lead with a DBS system capable of multiple independent current source control (MICC) for use in managing symptoms of levodopa-responsive Parkinson's disease (PD) are reported.

Novel Programming Features Help Alleviate Subthalamic Nucleus Stimulation-Induced Side Effects.

Subthalamic nucleus deep brain stimulation (STN-DBS) is a widely used treatment for Parkinson's disease (PD) patients with motor complications, but can result in adverse effects (AEs) in a significant proportion of treated patients. The use of novel programming features including short pulse width (PW) and directional steering in alleviating stimulation-induced AEs has not been explored. To determine if programming with short PW, directional steering, or the combination of these novel techniques can improve stimulation-induced dysarthria, dyskinesia, and pyramidal AEs. Thirty-two consecutive PD patients who experienced reversible AEs of STN-DBS had optimization of their settings using either short PW, directional steering, or the combination, while ensuring equivalent control of motor symptoms. Pairwise comparisons of pre- and post-optimization adverse effect ratings were made. Patients were left on the alternative setting with the greatest benefit and followed up at 6 months. Modeling of volume of tissue activated (VTA) and charge per pulse (Qp) calculations were used to explore potential underlying mechanisms of any differences found. There were significant improvements in stimulation-induced dysarthria, dyskinesia, and pyramidal side effects after optimization. At 6 months, mean AE ratings remained significantly improved compared to pre-optimization ratings. Different patterns of shift in VTA for each AE, and Qp could be used to explain improvements using novel techniques. Stimulation-induced dysarthria, dyskinesia, and pyramidal AEs induced by STN-DBS can be improved by using novel programming techniques. These represent additional tools to conventional methods that can be used to address these AEs. © 2020 The Authors. Movement Disorders published by Wiley Periodicals LLC on behalf of International Parkinson and Movement Disorder Society.

Design of variable curvature lane changing control system based on inverse system decoupling

At present, the lane changing technology for a single driving environment has been relatively mature, but the actual situations are much more complicated, such as the changing curvature and the changes in road conditions. In this paper, a new lane changing obstacle avoidance control strategy for the variable curvature road was proposed. It has two stages including path planning for variable curvature lane changing and inverse system decoupling (ISD) control for path tracking. The first stage established the lane changing path models for the variable curvature road. A longitudinal-lateral safe distance model was proposed to constrain the safe boundary of the lane changing path. The second stage proposed a dynamic decoupling method for longitudinal and lateral motion based on the inverse system decoupling, a direct yaw moment and active front wheel steering coordinated control method was designed. The inverse system decoupling algorithm can correct the single point preview (SPP) method to improve the stability and the path tracking accuracy in the lane changing obstacle avoidance process. The strategy was simulated by CarSim/Simulink co-simulation, and the experiments were carried out on the hardware-in-the-loop platform. The results show that the proposed control strategy can effectively avoid obstacles when the vehicle is driving on the variable curvature road. Besides, for the different road conditions and the strong non-linearity generated during the lane changing process, the control strategy can reduce the tracking error by a maximum of 32.7%, both the yaw rate and side slip angle can be controlled in a smaller range.

Enhanced Steering and Drive Adaptations of Modified Ride-On Toy Cars for Improved Directional Control in Very Young Children With Severe Multiple Developmental Impairments.

Background and Purpose: One emerging power mobility device (PMD) option that has gained recognition as a means for a cost-effective introduction to power mobility for young children is the battery powered modified ride-on toy car. Many groups, nationally and internationally, have been modifying battery powered ride-on toy cars by adding seating support and a large center placed push button switch for motor activation. The purpose of this technical report is to introduce an enhanced steering and drive system based on proportional control through a joystick.Key Points: This report offers (1) a technical description of these modifications that allow directional steering and programmable starting and driving velocity, (2) an example of a modified ride on toy, including common seating modifications, and (3) a short summary of results from a group of 7 children under the age of six with complex, severe disabilities.Clinical Impact: Although proportional joystick modifications are more complex than the common single switch activation, they allow children greater control to achieve self-initiated, self-directed movement that allow play, peer interaction, and exploration in their natural environments, even in the most highly complex cases. All seven children were able to intentionally self-initiate activation of the modified ride-on car and experience the subsequent movement.

Improving control effects of absence seizures using single-pulse alternately resetting stimulation (SARS) of corticothalamic circuit

Presently, we develop a simplified corticothalamic (SCT) model and propose a single-pulse alternately resetting stimulation (SARS) with sequentially applying anodic (A, “+”) or cathodic (C, “−”) phase pulses to the thalamic reticular (RE) nuclei, thalamus-cortex (TC) relay nuclei, and cortical excitatory (EX) neurons, respectively. Abatement effects of ACC-SARS of RE, TC, and EX for the 2Hz–4Hz spike and wave discharges (SWD) of absence seizures are then concerned. The m:n on-off ACC-SARS protocol is shown to effectively reduce the SWD with the least current consumption. In particular, when its frequency is out of the 2 Hz–4Hz SWD dominant rhythm, the desired seizure abatements can be obtained, which can be further improved by our proposed directional steering (DS) stimulation. The dynamical explanations for the SARS induced seizure abatements are lastly given by calculating the averaged mean firing rate (AMFR) of neurons and triggering averaged mean firing rates (TAMFRs) of 2Hz–4Hz SWD.