Trajectory Guidance Research Articles

Advanced Top-Attack Trajectory Guidance Law with Impact Angle Constraints

Advanced Top-Attack Trajectory Guidance Law with Impact Angle Constraints

Study of the degree of controllability of a spacecraft during flight along a reference trajectory in the atmosphere of Mars

The process of landing a spacecraft on Mars or another planet is studied. During the descent of the aircraft in the atmosphere, a test mathematical model of guidance is chosen. The criterion of the controllability degree is applied to determine the degree of controllability when moving along various trajectories. Mathematical modeling of the spacecraft guidance process during descent in the Martian atmosphere according to tracking scheme of the program trajectory by using a control algorithm with active disturbance compensation and a proportionalintegralderivative (PID) adjuster is considered. Based on the results of the simulation, it is possible to evaluate and compare the optimality of various reference trajectories by using a criterion that is used as an indicator to study the influence of trajectory parameters on the landing process from the point of view of controllability. Keywords spacecraft, degree of controllability criterion, linear non-stationary system, reference trajectory guidance, control with active disturbance compensation

Centroidal Voronoi Tessellation and Model Predictive Control–Based Macro-Micro Trajectory Optimization of Microsatellite Swarm

Probabilistic swarm guidance enables autonomous microsatellites to generate their individual trajectories independently so that the entire swarm converges to the desired distribution shape. However, it is essential to avoid crowding for reducing the possibility of collisions between microsatellites. To determine the collision-free guidance trajectory of each microsatellite from the current position to the target space, a collision avoidance algorithm is necessary. A synthesis method is proposed that generate the collision avoidance trajectories. The idea is that the trajectory planning is divided into macro-planning and micro-planning; macro-planning guides where the microsatellites move step by step from the initial cube to the target cube by probabilistic swarm guidance with Centroidal Voronoi tessellation, while the micro-planning is to generate the optimal path for each step and finally reach the specified position in the target cube by model predictive control. Simulation results are presented for the collision-free guidance trajectory of microsatellites to verify the benefits of this planning scheme.

Interactive and Immersive Process-Level Digital Twin for Collaborative Human–Robot Construction Work

Human cognition plays a critical role in construction work, particularly in the context of high-level task planning and in-field improvisation. On the other hand, robots are adept at performing numerical computation and repetitive physical tasks with precise motion control. The unstructured and complex nature of construction environments and the inability to maintain tight tolerances in assembled workpieces pose several unique challenges to the wide application of robots in construction work. Thus, the robotization of field construction processes is best conceived as a collaborative human–robot endeavor that takes advantage of both human and robot intelligence as well as robots’ physical operation capabilities to overcome uncertainties and successfully perform useful construction work onsite. This paper proposes an interactive and immersive process-level digital twin (I2PL-DT) system in virtual reality (VR) that integrates visualization and supervision, task planning and execution, and bidirectional communication to enable collaborative human–robot construction work. In this work paradigm, the human worker is responsible for high-level task planning and work process supervision. The robot undertakes workspace sensing and monitoring, detailed motion planning, and physical execution of the work. A drywall installation case study involving imperfect rough carpentry (wall framing) is presented using a KUKA mobile industrial robotic arm emulator. A human-in-the-loop study involving 20 subjects was conducted for system verification and to collect feedback for future improvements. The experimental results show that users can use the system to specify work sequences, select optimal task plans, and perform robot trajectory guidance after simple training and felt positive about the system functions and user experience. The system demonstrates the potential of transitioning the role of construction workers from physical task performers to robot supervisors. In addition, the system establishes a promising framework for construction workers to remotely collaborate with onsite construction robots.

Model predictive control for reusable space launcher guidance improvement

This work aims to demonstrate the benefits and limitations of an on-board Guidance for reusable launch vehicles, as well as to tradeoff different Model Predictive Control (MPC)-based Guidance and Control (G&C) architectures, exploiting, in particular, recent advances on successive convexification algorithms for optimization problems. Leading space agencies and private companies are investing on the development of reusable space launchers to reduce the cost to access the space. Indeed, that cost is one of the major deterrents in space exploration and space utilization. Reusability is, therefore, the unanimous solution to lower costs, and get a reliable and fast space access. Among many technological enhancements, the guidance, navigation, and control plays a crucial role: precise pinpoint landing capabilities or mid-air recovery, in fact, are mandatory. Indeed, the capability for generating re-optimized guidance trajectories on-board in real-time based on current flight conditions promises to improve the system performance, allows for fault tolerance capabilities, and reduces mission preparation costs. The work focuses especially on the implementation of a successive convexification Model Predictive Control guidance algorithm which solves the 6 Degree-of-Freedom (DoF) Powered Descent Guidance problem (PDG). The novelty of that work is applying a model predictive-based technique to a complex dynamic environment, trading off different solutions to the problem and relying on results obtained by using an industrial simulation framework. The robustness of the proposed approach is tested in several operative scenarios and the feasibility of real-time implementation is studied. For what concerns the trajectory optimization routine, the formulation of the problem, while initially being non-convex, is convexified. This is performed by implementing a successive convexification algorithm, which obtains a sub-optimal solution of the original problem in a fraction of the time required by a global optimizer, by solving a Second Order Cone Programming (SOCP) problem. This method allows coping with different kinds of dynamics nonlinearities, as well as cost functions and constraints. By presenting the approach and critically discussing the obtained results, the work provides an overview of the different methodologies available in the literature and assesses the limits of those approaches when applied to highly nonlinear scenarios, with large dispersions of uncertain parameters, as it is the case of reusable launch vehicles.

Establishing a Women-in-Radiology Group: A Toolkit From the American Association for Women in Radiology

Despite increasing representation in medical schools and surgical specialties, recruitment of women into radiology has failed to exhibit commensurate growth. Furthermore, women are less likely than men to advance to leadership roles in radiology. A women-in-radiology (WIR) group provides a robust support system that has been shown to produce numerous benefits to the group's individual participants as well as the group's institution or practice. These benefits include development of mentor-ship relationships, guidance of career trajectories, improved camaraderie, increased participation in scholarly projects, and increased awareness of gender-specific issues. This article describes a recommended pathway to establishing a WIR group, with the goal of fostering sponsorship and promoting leadership, recruitment, and advancement of women in radiology. We consider barriers to implementation and review resources to facilitate success, including a range of resources provided by the American Association for Women in Radiology. By implementing the provided framework, radiologists at any career stage can start a WIR group, to promote the advancement of their female colleagues.

A Practical Trajectory Tracking Scheme for a Twin-Propeller Twin-Hull Unmanned Surface Vehicle

Trajectory tracking is a basis of motion control for Unmanned Surface Vehicles (USVs), which has been researched well for common USVs. The twin-propeller and twin-hull USV (TPTH-USV) is a special vehicle for applications due to its good stability and high load. We propose a three-layered architecture of trajectory tracking for the TPTH-USV which explicitly decomposes into trajectory guidance, a motion limitator and controller. The trajectory guidance transforms an expected trajectory into an expected speed and expected course in a kinematic layer. The motion limitator describes some restriction for motion features of the USV in the restriction layer, such as the maximum speed and maximum yaw rate. The controller is to control the speed and course of the USV in the kinetic layer. In the first layer, an adaptive line-of-sight guidance law is designed by regulating the speed and course to track a curved line considering the sideslip angle. In the second layer, the motion features are extracted from an identified speed and course coupled model. In the last layer, the course and speed controller are designed based on a twin-PID controller. The feasibility and practicability of the proposed trajectory tracking scheme is validated in sea experiments by a USV called ‘Jiuhang 490’.

Digital Transformation and the New Normal in China: How Can Enterprises Use Digital Technologies to Respond to COVID-19?

The COVID-19 pandemic, a worldwide health and humanitarian crisis, has created unique challenges for citizens, governments, and organizations alike. Business leaders ask ‘what is the new normal, post-pandemic?’ while industries become more complex and uncertain. Premises sit empty, employees work remotely, and customers possess less disposable income. However bleak, opportunities do exist. Organizations will, however, need to transform. Technology will need to be used to respond to the pandemic, and organizations must re-structure to better function. This paper examines the role that digital technologies can play in responding to pandemics and outlines four classifications of digital technologies for pandemic response. An as-is/to-be pathway analysis is presented using case studies from Chinese enterprises to provide trajectory guidance for moving forward to the new normal. After analysis from an incorporated technology-centric and business model-based framework perspective, six fundamental enterprise strategies are presented that are derived from literature and empirical observations.

Visual anticipation of the future path: Predictive gaze and steering.

Skillful behavior requires the anticipation of future action requirements. This is particularly true during high-speed locomotor steering where solely detecting and correcting current error is insufficient to produce smooth and accurate trajectories. Anticipating future steering requirements could be supported using “model-free” prospective signals from the scene ahead or might rely instead on model-based predictive control solutions. The present study generated conditions whereby the future steering trajectory was specified using a breadcrumb trail of waypoints, placed at regular intervals on the ground to create a predictable course (a repeated series of identical “S-bends”). The steering trajectories and gaze behavior relative to each waypoint were recorded for each participant (N = 16). To investigate the extent to which drivers predicted the location of future waypoints, “gaps” were included (20% of waypoints) whereby the next waypoint in the sequence did not appear. Gap location was varied relative to the S-bend inflection point to manipulate the chances that the next waypoint indicated a change in direction of the bend. Gaze patterns did indeed change according to gap location, suggesting that participants were sensitive to the underlying structure of the course and were predicting the future waypoint locations. The results demonstrate that gaze and steering both rely upon anticipation of the future path consistent with some form of internal model.

Comparison of robotic and manual implantation of intracerebral electrodes: a single-centre, single-blinded, randomised controlled trial

There has been a significant rise in robotic trajectory guidance devices that have been utilised for stereotactic neurosurgical procedures. These devices have significant costs and associated learning curves. Previous studies reporting devices usage have not undertaken prospective parallel-group comparisons before their introduction, so the comparative differences are unknown. We study the difference in stereoelectroencephalography electrode implantation time between a robotic trajectory guidance device (iSYS1) and manual frameless implantation (PAD) in patients with drug-refractory focal epilepsy through a single-blinded randomised control parallel-group investigation of SEEG electrode implantation, concordant with CONSORT statement. Thirty-two patients (18 male) completed the trial. The iSYS1 returned significantly shorter median operative time for intracranial bolt insertion, 6.36 min (95% CI 5.72–7.07) versus 9.06 min (95% CI 8.16–10.06), p = 0.0001. The PAD group had a better median target point accuracy 1.58 mm (95% CI 1.38–1.82) versus 1.16 mm (95% CI 1.01–1.33), p = 0.004. The mean electrode implantation angle error was 2.13° for the iSYS1 group and 1.71° for the PAD groups (p = 0.023). There was no statistically significant difference for any other outcome. Health policy and hospital commissioners should consider these differences in the context of the opportunity cost of introducing robotic devices.Trial registration: ISRCTN17209025 (https://doi.org/10.1186/ISRCTN17209025).

Model Predictive Control for Automatic Carrier Landing with Time Delay

This paper focuses on the problem of automatic carrier landing control with time delay, and an antidelay model predictive control (AD-MPC) scheme for carrier landing based on the symplectic pseudospectral (SP) method and a prediction error method with particle swarm optimization (PE-PSO) is designed. Firstly, the mathematical model for carrier landing control with time delay is given, and based on the Padé approximation (PA) principle, the model with time delay is transformed into an equivalent nondelay one. Furthermore, a guidance trajectory based on the predicted trajectory shape and position deviation is designed in the MPC framework to eliminate the influence of carrier deck motion and real-time error. At the same time, a rolling optimal control block is designed based on the SP algorithm, in which the steady-state carrier air wake compensation is introduced to suppress the interference of the air wake. On this basis, the PE-PSO delay estimation algorithm is proposed to estimate the unknown delay parameter in the equivalent control model. The simulation results show that the delay estimation error of the PE-PSO algorithm is smaller than 2 ms, and the AD-MPC algorithm proposed in this paper can limit the landing height error within ±0.14 m under the condition of multiple disturbances and system input delay. The control accuracy of AD-MPC is much higher than that of the traditional pole assignment algorithm, and its computational efficiency meets the requirement of real-time online tracking.

Multi-user accessible indoor infrared optical wireless communication systems employing VIPA-based 2D optical beam-steering technique.

Infrared optical wireless communication system can achieve ultrahigh capacity and high privacy data transmission. However, for using narrow infrared laser beam as carrier to transmit signal, the high-speed data transmission can only be achieved by point-to-point connection. With the rapid number increasement of consumer electronic devices, such connection method puts a heavy burden on the number of transmitters. Thus, the transmitting end with the point-to-multipoint capability or multi-user accessibility is required. In this paper, we present a multi-user accessible indoor infrared optical wireless communication system employing passive diffractive optics based on a virtually imaged phased array (VIPA). Multiple beams can be generated in a point-to-multipoint scheme by using VIPA-based beam-steering antenna (BSA). On the other hand, by tuning wavelength of laser source, fast 2D steering of multiple beams with the same steering trajectory is supported, which can be used for user ends with changing locations. In the experiment, 5 beams are generated by utilizing only one transmitter. All five beams can realize 12.5 Gb/s on-off-keying (OOK) data rate transmission. Free-space optical wireless transmission at 3.6-m communication distance is demonstrated for system performance verification and evaluation. a total 3.44°×7.9° scanning field of view of five beams is achieved.

Netrin 1-Mediated Role of the Substantia Nigra Pars Compacta and Ventral Tegmental Area in the Guidance of the Medial Habenular Axons.

The fasciculus retroflexus is an important fascicle that mediates reward-related behaviors and is associated with different psychiatric diseases. It is the main habenular efference and constitutes a link between forebrain regions, the midbrain, and the rostral hindbrain. The proper functional organization of habenular circuitry requires complex molecular programs to control the wiring of the habenula during development. However, the mechanisms guiding the habenular axons toward their targets remain mostly unknown. Here, we demonstrate the role of the mesodiencephalic dopaminergic neurons (substantia nigra pars compacta and ventral tegmental area) as an intermediate target for the correct medial habenular axons navigation along the anteroposterior axis. These neuronal populations are distributed along the anteroposterior trajectory of these axons in the mesodiencephalic basal plate. Using in vitro and in vivo experiments, we determined that this navigation is the result of netrin 1 attraction generated by the mesodiencephalic dopaminergic neurons. This attraction is mediated by the receptor deleted in colorectal cancer (DCC), which is strongly expressed in the medial habenular axons. The increment in our knowledge on the fasciculus retroflexus trajectory guidance mechanisms opens the possibility of analyzing if its alteration in mental health patients could account for some of their symptoms.

A 3D trajectory tracking algorithm for AUV

This paper mainly studies the trajectory tracking problem of six-degree-of-freedom AUV in seafloor three-dimensional space. The mathematical model of AUV is established, the trajectory guidance law is designed by LOS method, the speed and rudder force are compensated by adding PID controller, and the stability of the system is proved by Lyapunov stability criterion. Taking Remus100 as an example, the trajectory tracking simulation of straight line and helix in space is carried out. The simulation results show that the trajectory tracking algorithm can realize the trajectory tracking of AUV.

Attuning to the needs of structural socially isolated older adults with complex problems: the experiences of social workers with personal guidance trajectories for a less-researched group.

Many interventions to combat the social isolation of older adults are hardly effective because they ignore both the heterogeneity of the target group and the uniqueness of the individual experiences of social isolation. In order to be effective, interventions must meet the individual needs of specific clients. In this study, we aim to gain insight into the process in which professionals seek to understand how clients assess their situation, and what this means for the help they provide. We investigated how social workers in one‐to‐one guidance trajectories try to attune to the needs of the clients they accompany and what considerations they make in doing so.The study was conducted between 2014 and 2017 in the city of Rotterdam in the Netherlands. Participants were 20 social workers of 8 social work agencies who provided guidance to community‐dwelling older adults who have been isolated for a long time and have problems in multiple life domains. We analysed 36 research‐driven logbooks, written by the social workers, which contain case study descriptions with information about specific clients who belong to the target group of this study. We also interviewed the individual social workers and organised six focus groups with 8–12 of the participating social workers.Our findings make clear how social workers try to identify the needs of their clients and provide help that is tailored to their possibilities and ambitions. By giving recognition to the emotions and situations of their clients, and by practical problem‐solving, they build a relationship with the older adults in which adequate help is accepted. The professionals set modest goals; their guidance helps stabilise the existing situation and may also contribute to the self‐reliance of their clients. This knowledge will be highly valuable in the developing and implementation of programmes and interventions for this less‐researched group.

Drivers use active gaze to monitor waypoints during automated driving

Automated vehicles (AVs) will change the role of the driver, from actively controlling the vehicle to primarily monitoring it. Removing the driver from the control loop could fundamentally change the way that drivers sample visual information from the scene, and in particular, alter the gaze patterns generated when under AV control. To better understand how automation affects gaze patterns this experiment used tightly controlled experimental conditions with a series of transitions from ‘Manual’ control to ‘Automated’ vehicle control. Automated trials were produced using either a ‘Replay’ of the driver’s own steering trajectories or standard ‘Stock’ trials that were identical for all participants. Gaze patterns produced during Manual and Automated conditions were recorded and compared. Overall the gaze patterns across conditions were very similar, but detailed analysis shows that drivers looked slightly further ahead (increased gaze time headway) during Automation with only small differences between Stock and Replay trials. A novel mixture modelling method decomposed gaze patterns into two distinct categories and revealed that the gaze time headway increased during Automation. Further analyses revealed that while there was a general shift to look further ahead (and fixate the bend entry earlier) when under automated vehicle control, similar waypoint-tracking gaze patterns were produced during Manual driving and Automation. The consistency of gaze patterns across driving modes suggests that active-gaze models (developed for manual driving) might be useful for monitoring driver engagement during Automated driving, with deviations in gaze behaviour from what would be expected during manual control potentially indicating that a driver is not closely monitoring the automated system.

A cooperative driving framework for urban arterials in mixed traffic conditions

Enabling technologies of connected and automated vehicles (CAVs) bring new opportunities to signalized intersection control. CAVs not only provide a new source of data for traffic management but also can be controlled as actuators to improve traffic flow. This study proposes a hierarchical and implementation-ready cooperative driving framework with a mixed traffic composition of CAVs, connected vehicles (CVs), and regular vehicles (RVs) for urban arterials. The proposed framework combines centralized and distributed control concepts, where the infrastructure generates optimal signal timing plans and provides high-level trajectory guidance to the CAVs while detailed trajectories are generated by each vehicle. The system consists of three levels of models. At the vehicle level, a state transition diagram is designed for different modes of operations of CAVs including eco-trajectory planning, cooperative adaptive cruise control (CACC) and collision avoidance. At the intersection level, a mixed-integer linear programming (MILP) problem is formulated to optimize the signal timing plan and arrival time of CAVs, with consideration of CACC platooning behaviors. At the corridor level, link performance functions are applied to calculate the total delay of the coordinated phases of each intersection, and a linear programming (LP) problem is formulated to optimize the offsets for every cycle, which are then passed to the intersection level. Simulation results from a calibrated real-world arterial corridor show that both mobility and fuel economy benefits from the cooperative driving framework. The total delay is reduced by 2.2%−33.0% and fuel consumption by 3.9%−7.4%, with different mixture of vehicle compositions and CAV penetration rates (e.g., 0%−100%). Sensitivity analysis on volume fluctuation is performed, which confirms the benefits of the dynamic offset optimization.

The current state of navigation in robotic spine surgery.

The advent and widespread adoption of pedicle screw instrumentation prompted the need for image guidance in spine surgery to improve accuracy and safety. Although the conventional method, fluoroscopy, is readily available and inexpensive, concerns regarding radiation exposure and the drive to provide better visual guidance spurred the development of computer-assisted navigation. Contemporaneously, a non-navigated robotic guidance platform was also introduced as a competing modality for pedicle screw placement. Although the robot could provide high precision trajectory guidance by restricting four of the six degrees of freedom (DOF), the lack of real-time depth control and high capital acquisition cost diminished its popularity, while computer-assisted navigation platforms became increasingly sophisticated and accepted. The recent integration of real-time 3D navigation with robotic platforms has resulted in a resurgence of interest in robotics in spine surgery with the recent introduction of numerous navigated robotic platforms. The currently available navigated robotic spine surgery platforms include the ROSA Spine Robot (Zimmer Biomet Robotics formerly Medtech SA, Montpellier, France), ExcelsiusGPS® (Globus Medical, Inc., Audubon, PA, USA), Mazor X spine robot (Medtronic Navigation Louisville, CO; Medtronic Spine, Memphis, TN; formerly Mazor Robotics, Caesarea, Israel) and TiRobot (TINAVI Medical Technologies, Beijing, China). Here we provide an overview of these navigated spine robotic platforms, existing applications, and potential future avenues of implementation.

Usability of cooperative surgical telemanipulation for bone milling tasks

PurposeCooperative surgical systems enable humans and machines to combine their individual strengths and collaborate to improve the surgical outcome. Cooperative telemanipulated systems offer the widest spectrum of cooperative functionalities, because motion scaling is possible. Haptic guidance can be used to assist surgeons and haptic feedback makes acting forces at the slave side transparent to the operator, however, overlapping and masking of forces needs to be avoided. This study evaluates the usability of a cooperative surgical telemanipulator in a laboratory setting.MethodsThree experiments were designed and conducted for characteristic surgical task scenarios derived from field studies in orthopedics and neurosurgery to address bone tissue differentiation, guided milling and depth sensitive milling. Interaction modes were designed to ensure that no overlapping or masking of haptic guidance and haptic feedback occurs when allocating information to the haptic channel. Twenty participants were recruited to compare teleoperated modes, direct manual execution and an exemplary automated milling with respect to usability.ResultsParticipants were able to differentiate compact and cancellous bone, both directly manually and teleoperatively. Both telemanipulated modes increased effectiveness measured by the mean absolute depth and contour error for guided and depth sensitive millings. Efficiency is decreased if solely a boundary constraint is used in hard material, while a trajectory guidance and manual milling perform similarly. With respect to subjective user satisfaction trajectory guidance is rated best for guided millings followed by boundary constraints and the direct manual interaction. Haptic feedback only improved subjective user satisfaction.ConclusionA cooperative surgical telemanipulator can improve effectiveness and efficiency close to an automated execution and enhance user satisfaction compared to direct manual interaction. At the same time, the surgeon remains part of the control loop and is able to adjust the surgical plan according to the intraoperative situation and his/her expertise at any time.

‘She shouldn't cross the line’: experiential effectivity of social guidance trajectories for socially isolated older adults with complex problems

AbstractSocial isolation of older adults is difficult to break through, and interventions that focus on network development or enhanced social participation are hardly effective, especially when the older adults have been isolated for a long time and have problems in multiple life domains. This study aimed to investigate the needs and subjective experiences of this less-researched group and obtain a deeper understanding of their goals and priorities. The study involved a qualitative study with 25 socially isolated persons who receive assistance from a social worker in an individual guidance trajectory. Data were collected via repeated in-depth interviews with the older adults. By directing the focus towards their subjective experiences, the study gives insight into the ‘experiential effectivity’ of the intervention. It shows what their experienced problems were, and to what degree they benefited from the intervention in this respect. The experience of personal attention and involvement of the social workers represents the most relevant results for them. The participants have no need for network development or engagement in local communities. Yet, the help offered by the social workers produces other results for them, such as solved practical problems, emotional support, more self-sufficiency, a point of contact or a safety net that was not there before. This knowledge can help to improve the quality of intervention for this target group.