Continuous Rotation Research Articles

Continuous adaptive gaits manipulation for three-fingered robotic hands via bioinspired fingertip contact events

The remarkable skill of changing its grasp status and relocating its fingers to perform continuous in-hand manipulation is essential for a multifingered anthropomorphic hand. A commonly utilized method of manipulation involves a series of basic movements executed by a high-level controller. However, it remains unclear how these primitives evolve into sophisticated finger gaits during manipulation. Here, we propose an adaptive finger gait-based manipulation method that offers real-time regulation by dynamically changing the primitive interval to ensure the force/moment balance of the object. Successful manipulation relies on contact events that act as triggers for real-time online replanning of multifinger manipulation. We identify four basic motion primitives of finger gaits and create a heuristic finger gait that enables the continuous object rotation of a round cup. Our experimental results verify the effectiveness of the proposed method. Despite the constant breaking and reengaging of contact between the fingers and the object during manipulation, the robotic hand can reliably manipulate the object without failure. Even when the object is subjected to interfering forces, the proposed method demonstrates robustness in managing interference. This work has great potential for application to the dexterous operation of anthropomorphic multifingered hands.

Kinematic calibration and feedforward control of a heavy-load manipulator using parameters optimization by an ant colony algorithm

AbstractMost of the currently available three-degree-of-freedom manipulators are light load and cannot achieve full continuous rotation; given this, we designed a heavy-load manipulator that achieves unrestricted and continuous rotation. Due to manufacturing and assembly errors, parameter deviations between the real manipulator and its underlying theoretical model were unavoidable. Because of the lack of high-precision, high-frequency, and real-time closed-loop detection methods, we proposed a type of kinematics calibration of parameterized ant colony optimization and feedforward control methods. This was done to achieve high-precision motion control. First, an error model combining structural parameters and joint output angles was established, and the global sensitivity of each error source was analyzed to distinguish both primary and secondary sources. Based on the measured data of a laser tracker, the ant colony optimization was then used to identify six error sources. This resulted in both link length and joint driving errors of the designed manipulator. As it is a type of systematic error, the rounding error of the theoretical trajectory was carefully analyzed, and feedforward control methods with different coefficients were designed to further improve positioning accuracy based on the kinematic calibration. Experimental results showed that the proposed kinematic calibration and feedforward control methods achieved relatively precise motion control for the designed manipulator.

How to load your auto carrier. A hybrid packing approach for the auto-carrier loading problem

The distribution of new vehicles is a critical cost factor for automotive original equipment manufacturers (OEMs). While trains are the ideal mode for overland transport, OEMs often opt for road transport via auto carriers due to flexibility reasons or unavailability of rail networks. Auto carriers are specialized trucks equipped with flexible loading platforms. Finding the optimal configuration of platforms can be a difficult task due to passenger vehicles varying in size, shape, and weight. This problem is known as the auto-carrier loading problem (ACLP). The current literature deals with the ACLP on a strategic level with the goal to maximize transport capacities. However, it neglects the resulting increase in operational complexity.In this paper, we present a hybrid packing approach to solve the ACLP on an operational level. Our approach considers the shapes of the vehicles as polygons and incorporates an approximation of continuous rotation by combining a geometric algorithm with a mixed integer model formulation. We aim not only to maximize loading capacities but also to provide instructions for truck drivers on how to arrange the vehicles on the truck. We conduct a proof of concept (POC) with actual auto carriers to verify the feasibility of our approach and to quantify potential benefits for our industry partner. The POC confirms that our approach reliably generates feasible and comprehensive loading instructions. Not only could the implementation of our approach reduce lead times and transportation damages, but in addition, could completely automate the manual load creation process in distribution centers.

Root canal retreatment of root canals filled with "Neo MTA 2" and epoxy resin, using continuous and asymmetric reciprocal rotation systems: In vitro study.

The study aimed to compare the amount of extrusion, the time taken to achieve apical patency and duration for removing filling material during the retreatment of teeth filled with NeoMTA 2® (Avalon Biomed, Houston, TX, USA), a calcium silicate hydraulic cement and AHPlus™ (Denstsply, Konstanz, Germany), a resin-based cement, using continuous rotation and asymmetric reciprocating rotation instruments. 60 monoradicular human teeth were selected and instrumented with Race #35.06 (FKG Dentaire, La Chaux-de-Fonds, Switzerland). The teeth were randomly assigned to two groups based on the cement used for filling (n = 30 each) AHPlus™ and NeoMTA 2®. Both groups were obturated with gutta-percha, using the lateral condensation technique. During non-surgical retreatments, each group was further divided into two subgroups: D-Race (FKG) and Reciproc (VDW, Munich, Germany) (n = 15 each). The total time to achieve apical patency and complete the retreatment were recorded. Extruded debris were collected and weighted. Student t-tests were employed for mean comparisons to assess significant differences between variables. No statistically significant differences were found in terms of type of cement and apical extrusion. Regarding the rotation system, using the Reciproc system resulted in longer time to achieve patency and retreatment times compared to D-Race system, with statistically significant differences (P< 0.05). All systems used in retreatment led to apical extrusion. Apical patency was achieved in all cases. Key words:D-Race, Reciproc, calcium silicate-based cement, root canal retreatment.

QUICKeR: Quicker Updates Involving Continuous Key Rotation

Since the advent of cloud computing, storing large quantities of sensitive data on remote services have demanded secure encryption practices to maintain data privacy. Merely encrypting data at-rest leaves ciphertexts vulnerable to inevitable key leakage from mismanaged keys, side-channel attacks, and security bugs. To combat this, we propose QUICKeR, a system to facilitate continuous key rotation and ciphertext updates. Unfortunately, continuous ciphertext updates from key rotation interferes with routine access operations by introducing race conditions and performance bottlenecks that preclude prior works from practical use. QUICKeR addresses these concerns through protocols that eliminate race conditions and even achieve the stronger linearizability correctness criterion. In addition, QUICKeR proposes three approaches to implement frequent ciphertext updates. We show how these different update schemes perform under different database bottlenecks. Finally, we demonstrate that QUICKeR is practical through end-to-end experiments showing that routine access operations are not significantly impacted by ciphertext update operations.

Toward Robust and Unconstrained Full Range of Rotation Head Pose Estimation.

Estimating the head pose of a person is a crucial problem for numerous applications that is yet mainly addressed as a subtask of frontal pose prediction. We present a novel method for unconstrained end-to-end head pose estimation to tackle the challenging task of full range of orientation head pose prediction. We address the issue of ambiguous rotation labels by introducing the rotation matrix formalism for our ground truth data and propose a continuous 6D rotation matrix representation for efficient and robust direct regression. This allows to efficiently learn full rotation appearance and to overcome the limitations of the current state-of-the-art. Together with new accumulated training data that provides full head pose rotation data and a geodesic loss approach for stable learning, we design an advanced model that is able to predict an extended range of head orientations. An extensive evaluation on public datasets demonstrates that our method significantly outperforms other state-of-the-art methods in an efficient and robust manner, while its advanced prediction range allows the expansion of the application area. We open-source our training and testing code along with our trained models: https://github.com/thohemp/6DRepNet360.

Soil management affects soil C and N stocks but not overall soil health

Soil health describes a soil’s capacity to function as a vital ecosystem that sustains plants, animals, and humans. It can be assessed by measuring specific soil physical, chemical, and biological parameters combined into a soil health index (SHI). The objective of this study was to evaluate the effect of management, depth, and their interaction on soil health indicators. We evaluated long-term continuous tillage, horticultural crop rotation, which had an antecedent tropical pumpkin/bean rotation, and a no-till avocado orchard in a Cumulic Haplustolls at the Juana Díaz Agricultural Experiment Substation. Soil samples were taken at 0 to 15, 15 to 30, 30 to 50, 50 to 75, and 75 to 100 cm intervals using a hydraulic probe. Soil pH, electrical conductivity, bulk density, dry stable aggregates, mean weight diameter, tensile strength, carbon and nitrogen stocks, and water content were quantified. The data were analyzed in a multivariate ANOVA. Results were classified considering threshold values, and an SHI score was determined based on the simple additive method. Our findings show that the no-till avocado orchard had better soil physicochemical qualities, including higher C and N stocks, but this did not lead to an improved SHI score when compared with the continuous tillage crop rotation plot. Soil depth, management, and their interaction were significant effects in both management systems with a score of 0.55 on the SHI scale. These results imply that, although overall soil health is not affected, increased C concentration, no-till, and perennials have a favorable effect on SHI indicators in horticultural systems in the San Antón series.

Controller Design for a Soft Continuum Robot With Concurrent Continuous Rotation

Controller Design for a Soft Continuum Robot With Concurrent Continuous Rotation

Sand liquefaction in simple shear tests

Liquefaction is a phenomenon marked by a rapid loss of soil strength and stiffness, which generally occurs in loose saturated sandy deposit during earthquake because of the generation of excess pore water pressure. Several experimental researches concluded that liquefied soil behaves as a fluid during ground movement, but after the earthquake motion ceases, due to the dissipation of excess pore water pressure, the liquefied soil recovers its initial stiffness and returns to behave as a solid. Liquefaction resistance of sandy soil can be studied by means of Cyclic Simple Shear (CSS) test or Cyclic Triaxial (CTX) tests. While CTX tests are widely used in liquefaction studies due to their simplicity, CSS tests are more representative of stress conditions produced during an earthquake by simulating the continuous rotation of the principal stress axes. In this research the preliminary results of CSS tests carried out with confining rings on the sandy samples retrieved in the South of Sicily are reported. The apparatus is described in detail. All samples used were obtained from the same type of Italian sand by using same preparation method to minimize the number of factors influencing the results. Moreover, all tests were conducted by a single operator. All experimental results are reported in the plane cyclic resistance ratio (CRR) and number of cycles where liquefaction occurs (Nliq) in order to assess the liquefaction phenomenon.

STEM SerialED: achieving high-resolution data for ab initio structure determination of beam-sensitive nanocrystalline materials.

Serial electron diffraction (SerialED), which applies a snapshot data acquisition strategy for each crystal, was introduced to tackle the problem of radiation damage in the structure determination of beam-sensitive materials by three-dimensional electron diffraction (3DED). The snapshot data acquisition in SerialED can be realized using both transmission and scanning transmission electron microscopes (TEM/STEM). However, the current SerialED workflow based on STEM setups requires special external devices and software, which limits broader adoption. Here, we present a simplified experimental implementation of STEM-based SerialED on Thermo Fisher Scientific STEMs using common proprietary software interfaced through Python scripts to automate data collection. Specifically, we utilize TEM Imaging and Analysis (TIA) scripting and TEM scripting to access the STEM functionalities of the microscope, and DigitalMicrograph scripting to control the camera for snapshot data acquisition. Data analysis adapts the existing workflow using the software CrystFEL, which was developed for serial X-ray crystallography. Our workflow for STEM SerialED can be used on any Gatan or Thermo Fisher Scientific camera. We apply this workflow to collect high-resolution STEM SerialED data from two aluminosilicate zeolites, zeolite Y and ZSM-25. We demonstrate, for the first time, ab initio structure determination through direct methods using STEM SerialED data. Zeolite Y is relatively stable under the electron beam, and STEM SerialED data extend to 0.60 Å. We show that the structural model obtained using STEM SerialED data merged from 358 crystals is nearly identical to that using continuous rotation electron diffraction data from one crystal. This demonstrates that accurate structures can be obtained from STEM SerialED. Zeolite ZSM-25 is very beam-sensitive and has a complex structure. We show that STEM SerialED greatly improves the data resolution of ZSM-25, compared with serial rotation electron diffraction (SerialRED), from 1.50 to 0.90 Å. This allows, for the first time, the use of standard phasing methods, such as direct methods, for the ab initio structure determination of ZSM-25.

Formation and strengthening mechanism of kink bands in an ultra-coarse-grained Fe-Cr-Al alloy

Fe-Cr-Al alloys, owing to their absence of allotropic transformation, require multiple cycles of rolling and recrystallization annealing processes to achieve substantial grain refinement, ultimately leading to the attainment of outstanding mechanical properties. However, the corresponding manufacturing costs will also increase greatly. In this work, we have proposed a new microstructural preparation process. Simply using warm rolling for an ultra-coarse-grained Fe-Cr-Al alloy to introduce lamellar kink bands (KBs) into the matrix, the mechanical properties can be significantly improved. By using electron backscatter diffraction (EBSD) and transmission electron microscopy (TEM), and combined with Schmid factor (SF) calculation, the formation mechanism of KBs has been revealed. When the slip plane and direction are nearly perpendicular to the loading force direction (LFD) during the continuous grain rotation, the dislocation wall will evolve into the KBs boundaries. Simultaneously, a huge orientation separation between the matrix and KBs will be produced. As strain continues to rise, KBs undergo a transformation, transitioning from low-angle-grain boundaries (LAGBs) to high-angle-grain boundaries (HAGBs), occasionally adopting a configuration as coincident site lattice (CSL) boundaries with reduced interface energy. Results of the tensile test, cyclic loading-unloading-reloading tensile test, and the strengthening calculation show that KBs can pronouncedly enhance the strength by their heterogeneous refinement on the original grains and hetero-deformation induced (HDI) strengthening effect from the dislocation density discrepancy between the matrix and internal KBs, the grains containing KBs (KBGs) and the grains without KBs (or KBs-free-grains, KFGs). The theoretical calculation value of the strengthening contribution from KBs on yield strength can be up to 225.5 MPa, with a minimum value exceeding 153 MPa. On the other hand, the ductility can be retained to some extent through stimulating the KBs boundary delamination mechanism. The present study provides a low-cost and feasible processing method for fabricating Fe-Cr-Al alloy with high strength and good ductility.

Investigating the Influence of Inlet Relative Humidity on Polymer Electrolyte Membrane Fuel Cell Performance by Visualizing 4-D Water Distributions in Gas Diffusion Layers

The catastrophic effects of atmospheric greenhouse gases and the depletion of non-renewable resources has led to the urgency to develop clean, sustainable energy technologies to meet increasing energy demands. However, the intermittent nature of current renewable energy technologies warrants the acquisition of on-demand renewable energy through either energy production or storage methods. Polymer electrolyte membrane fuel cells (PEMFCs) are promising candidates for this task, as they utilize the most abundant element on Earth, hydrogen, to produce high amounts of power under rapid changes in load with little to no greenhouse gas emissions (1). Therefore, PEMFCs have great potential to help offset the negative impact of atmospheric pollution due to excessive carbon emissions. However, liquid water management issues associated with high power output of the fuel cell typically leads to reduced performance and durability of the fuel cell, and thereby hinders global implementation of these devices (2). To minimize these losses and improve GDL material designs, an understanding of the relationship between product liquid water distributions in the cathode GDL and transport properties of PEMFCs under varying operating conditions is highly valuable. Previous works have characterized the effect of operating temperature on liquid water pathways and distributions in GDLs by visualizing operando PEMFCs with 3D imaging techniques such as X-ray computed tomography (CT) (3). The high-speed, high-resolution capabilities of these imaging techniques enable the visualization of dynamic pore-scale activity to elucidate transport mechanisms in the GDL.In this work, the effect of inlet relative humidity on the formation and distribution of liquid water pathways in cathode GDLs is investigated by imaging a PEMFC operando with synchrotron X-ray CT at high spatial resolution, enabling the resolution of water in the individual pores of the GDL. The contribution of a microporous layer (MPL) is also explored by imaging a cell with an MPL and without. Imaging is conducted on a specialized cell designed to facilitate continuous rotation about the CT stage, enabling fast acquisition of consecutive scans to achieve high temporal resolution useful for visualizing the dynamic development of preferential water pathways. Additionally, electrochemical impedance spectroscopy was performed to quantify mass transport losses. The sequence of CT images was utilized to capture the dynamics of liquid water development as well as stabilized water distributions. Visualizing the reconstructed images shows that as current increases, water production increases, and the development of water pathways to breakthrough at the flow field interface is observed. Additionally, results show that an increase in relative humidity led to a significant increase in cathode GDL water saturation.The contribution of this study to understanding transport mechanisms in GDL materials is significant to the characterization and optimal design of materials for improved PEMFC performance. Ultimately, the goal of this work is to accelerate the worldwide adoption of PEMFCs as a sustainable, reliable solution to replace conventional carbon-emitting energy sources.1. Alaswad et al., J. Hydrog. Energy, 41, (2016)2. Nagai et al., J. Power Sources, 435, (2019)3. D. Shum et al., Electrochem. Acta, 256, (2017)

Mathematical fundamentals of spherical kinematics of plate tectonics in terms of quaternions

To be a quantitative and testable tectonic model, plate tectonics requires spherical geometry and spherical kinematics in terms of finite rotations conveniently parametrized by their angle and axis and described by unit quaternions. In treatises on “Plate Tectonics” infinitesimal, instantaneous, and finite rotations, absolute and relative rotations are said to be applied to model the motion of tectonic plates. Even though these terms are strictly defined in mathematics, they are often casually used in geosciences. Here, their definitions are recalled and clarified as well as the terms rotation, orientation, and location on the sphere. For instance, infinitesimal rotations refer to a mathematical limit, when the angle of rotation tends to zero. Their rules do not apply to finite rotations, no matter how small their finite angles of rotation are. Mathematical approaches applying appropriate and feasible assumptions to model spherical motion of tectonic plates over geological times of hundreds of millions of years are derived including (i) sequences of incremental finite rotations, (ii) sequences of accumulating successive concatenations of finite rotations, and (iii) continuous rotations in terms of fully transient quaternions. The incremental and the accumulating approaches provide complementary views. While the relative Euler pole appears to migrate in the latter, it appears fixed in the former. Path, mean, and instantaneous velocity of the migrating Euler pole are derived as well as the angular and trajectoral velocity of the rotational motion about it. The approaches are illustrated by a geological example with actual data and a numerical yet geologically inspired example with artificial data. The former revisits the three‐plate scenario with stationary axes of two “absolute” rotations implying transient “relative” rotations about a migrating Euler pole and employs a proper plate‐circuit argument to determine them numerically without resorting to approximations. The latter applies an involved interplay of incremental and accumulating modeling inducing split–join cycles to approximate sinusoidal trajectories as reported to record plates' motion during the Gondwana breakup.

Influence of endodontic motors on the behaviour of root canal shaping instruments: an in vitro comparative study

AimsThe endodontic literature reports a lot of comparative study on endodontic instruments, concerning as well their geometry, instrumental dynamics, material, mechanical behavior or heat treatment. However, to our knowledge, no study has focused on the influence of endodontic motors on the shaping abilities of endodontic instruments. Thus, the aim of this study was to analyze the influence of the endodontic motors on root canal shaping instruments.MethodDual Move (MICRO-MEGA, Besançon, France), Canal Pro CL2i (COLTENE, Alstätten, Suisse), Canal Pro Jeni Motor (COLTENE, Alstätten, Suisse), Ai Motor (WOODPECKER, Guilin, China), Wave One motor (VDW, Postfach, Munich) and Smart A (WOODPECKER, Guilin, China) were pre-clinically compared in continuous rotation and reciprocating motion on a traction/compression bench using resin blocks. Canal shaping in continuous rotation and reciprocating motion were performed with One Curve and One RECI instruments (MICRO-MEGA, Besançon, France), respectively. The penetration/removal forces, making it possible to objectify the cutting effect and screwing effect of the instruments during root canal shaping, were analyzed.ResultsThe results showed (i) that endodontic motors influence the mechanical behavior of endodontic instruments, (ii) that the influence of the motors is essentially felt during reciprocating motion and (iii) that the reciprocating angles influence the mechanical behavior of endodontic instruments.ConclusionOnly endodontic instruments are widely studied in literature while endodontic motors have a direct influence on root canal treatment. This study analyzes the influence of the endodontic motors on root canal shaping instruments. This study tends to demonstrate that Jeni Motor could optimize the mechanical behavior of endodontic instruments.

High-resolution detection of pitch rotation in an optically confined hexagonal-shaped upconverting particle

A rigid body can have six degrees of freedom, of which three are with rotational origin. In the nomenclature of the airlines, the in-plane degree of rotational freedom can be called yaw while the first out-of-plane degree of freedom can be called pitch with the second one being called roll. Among these, only the yaw sense has been studied extensively in the optical tweezers literature, while the pitch rotation is starting to be explored. In this paper, we show a way to detect the pitch rotation in a hexagonal-shaped particle using photonic force microscopy using the forward scattered light under crossed polarizers and making it incident on a split photodiode. In this way, the pitch angle can be detected at high resolution and bandwidth. We apply this technique to detect continuous pitch rotation and also exhibit a power spectral density for an anisotropic particle optically trapped in a linearly polarized light and exhibiting Brownian motion.

Development of a “Green” Emulsion with a Milk Protein Hydrolysate: An Evaluation of Rheology, Texture, In Vitro Bioactivity, and Safety

Bioactive peptides are promising cosmetic active ingredients that can improve skin health and appearance. They exhibit a broad spectrum of activity, including anti-aging, antioxidant, antimicrobial, and anti-inflammatory effects. The aim of this study was to develop a safe, stable, and efficacious environmentally friendly (“green”) emulsion using a milk protein hydrolysate as a model active ingredient. Potential emulsions were formulated with biodegradable emollients, stabilized with naturally derived mixed emulsifier, and prepared by cold process. They were evaluated for rheological behavior (continuous rotation and oscillation tests), physical stability (dynamic mechanical thermal analysis—DMTA test), and texture profiles, as well as cytotoxic, antioxidant, and antimicrobial effects. Rheological characterization revealed shear-thinning flow behavior with yield point from continuous rotation tests and predominantly elastic character from oscillation (amplitude and frequency sweep) tests, with small structural change detected in the DMTA test. These results implied satisfactory rheological properties and good stability. Texture analysis revealed acceptable spreadability and substantivity of the emulsions. The protein hydrolysate showed antioxidant activity. The developed emulsions showed low antibacterial activity against selected microorganisms, but this was due to the action of preservatives, not peptides. All potential emulsions showed a desirable safety profile. The results obtained provide the basis for the next stage of formulation development, i.e., in vivo efficacy tests.

Efficiency and complications in root canal retreatment using nickel titanium rotary file with continuous rotation, reciprocating, or adaptive motion in curved root canals: a laboratory investigation

BackgroundIt is currently unknown whether rotary file motion affects the best outcome of root canal retreatment. This experimental study compared the efficacy, efficiency, and complications of single-use NiTi rotary files using continuous rotation, reciprocating, and adaptive motions in root canal filling removal in curved root canals. Reciproc blue R25 was used with reciprocating motion (RB), VDW.ROTATE retreatment files with continuous rotation (VR), and ProTaper NEXT X2 with continuous rotation (PTNc) or adaptive motion (PTNa).MethodsForty mesial root canals of extracted mandibular first and second molars with an angle of curvature between 20°–40° and a radius of curvature between 5 and 10 mm were collected. The specimens were instrumented and obturated with gutta-percha and AH Plus sealer using the continuous wave of condensation technique. The specimens were randomly divided into 4 retreatment groups (n = 10), RB, VR, PTNc, and PTNa. The percentage of root canal filling removal in each group was analyzed using Micro-Computed Tomography (µCT). The motor running time, total time, root canal complication, and instrument complication were recorded and statistically analyzed (p-value < 0.05).ResultsThe pre-operative root canal curvature and root canal filling volume were comparable among groups. The percentage of root canal filling removal from the whole canal in the PTNc, RB, PTNa, and VR group was 98%, 96%, 95%, and 93%, respectively. A significant difference was observed between the PTNc and VR groups for the whole canal and the apical-third part. The motor running time and total time were significantly different between the groups. Instrument fracture was observed at 40% in the VR and 20% in the PTNa group, but none in the RB and PTNc groups.ConclusionsThe ProTaper NEXT X2 with continuous rotation and RB files can be used with high efficacy and efficiency in curved root canal retreatment. Continuous rotation is more efficacious and efficient than adaptive motion when using the NiTi rotary file. Single file retreatment can be used in small canals with high efficacy, cost-effectiveness, and less time consumption.

Rotation of a Stealth CME on 2012 October 5 Observed in the Inner Heliosphere

Coronal mass ejections (CMEs) are subject to changes in their direction of propagation, tilt, and other properties. This is because CMEs interact with the ambient solar wind and other large-scale magnetic field structures. In this work, we report on the observations of the 2012 October 5 stealth CME using coronagraphic and heliospheric images. We find clear evidence of a continuous rotation of the CME, i.e., an increase in the tilt angle, estimated using the graduated cylindrical shell (GCS) reconstruction at different heliocentric distances, up to 58 R ⊙. We find a further increase in the tilt at L1 estimated from the toroidal and cylindrical flux rope fitting on the in situ observations of interplanetary magnetic field (IMF) and solar wind parameters. This study highlights the importance of observations of Heliospheric Imager (HI), on board the Solar Terrestrial Relations Observatory. In particular, the GCS reconstruction of CMEs in the HI field of view promises to bridge the gap between the near-Sun and in situ observations at the L1. The changes in the CME tilt have significant implications for the space weather impact of stealth CMEs.

Dual-Quaternion-Based SLERP MPC Local Controller for Safe Self-Driving of Robotic Wheelchairs

In this work, the motion control of a robotic wheelchair to achieve safe and intelligent movement in an unknown scenario is proposed. The primary objective is to develop a comprehensive framework for a robotic wheelchair that combines a global path planner and a model predictive control (MPC) local controller. The A* algorithm is employed to generate a global path. To ensure safe and directional motion for the wheelchair user, an MPC local controller is implemented taking into account the via points generated by an approach combined with dual quaternions and spherical linear interpolation (SLERP). Dual quaternions are utilized for their simultaneous handling of rotation and translation, while SLERP enables smooth and continuous rotation interpolation by generating intermediate orientations between two specified orientations. The integration of these two methods optimizes navigation performance. The system is built on the Robot Operating System (ROS), with an electric wheelchair equipped with 3D-LiDAR serving as the hardware foundation. The experimental results reveal the effectiveness of the proposed method and demonstrate the ability of the robotic wheelchair to move safely from the initial position to the destination. This work contributes to the development of effective motion control for robotic wheelchairs, focusing on safety and improving the user experience when navigating in unknown environments.

A fault-tolerant variational quantum algorithm with limited T-depth

We propose a variational quantum eigensolver (VQE) algorithm that uses a fault-tolerant (FT) gate-set, and is hence suitable for implementation on a future error-corrected quantum computer. VQE quantum circuits are typically designed for near-term, noisy quantum devices and have continuously parameterized rotation gates as the central building block. On the other hand, an FT quantum computer (FTQC) can only implement a discrete set of logical gates, such as the so-called Clifford+T gates. We show that the energy minimization of VQE can be performed with such an FT discrete gate-set, where we use the Ross–Selinger algorithm to transpile the continuous rotation gates to the error-correctable Clifford+T gate-set. We find that there is no loss of convergence when compared to the one of parameterized circuits if an adaptive accuracy of the transpilation is used in the VQE optimization. State preparation with VQE requires only a moderate number of T-gates, depending on the system size and transpilation accuracy. We demonstrate these properties on emulators for two prototypical spin models with up to 16 qubits. This is a promising result for the integration of VQE and more generally variational algorithms in the emerging FT setting, where they can form building blocks of the general quantum algorithms that will become accessible in an FTQC.