Showing papers on "Guidance system published in 2020"

Autonomous Crop Row Guidance Using Adaptive Multi-ROI in Strawberry Fields

Abstract: Automated robotic platforms are an important part of precision agriculture solutions for sustainable food production. Agri-robots require robust and accurate guidance systems in order to navigate between crops and to and from their base station. Onboard sensors such as machine vision cameras offer a flexible guidance alternative to more expensive solutions for structured environments such as scanning lidar or RTK-GNSS. The main challenges for visual crop row guidance are the dramatic differences in appearance of crops between farms and throughout the season and the variations in crop spacing and contours of the crop rows. Here we present a visual guidance pipeline for an agri-robot operating in strawberry fields in Norway that is based on semantic segmentation with a convolution neural network (CNN) to segment input RGB images into crop and not-crop (i.e., drivable terrain) regions. To handle the uneven contours of crop rows in Norway’s hilly agricultural regions, we develop a new adaptive multi-ROI method for fitting trajectories to the drivable regions. We test our approach in open-loop trials with a real agri-robot operating in the field and show that our approach compares favourably to other traditional guidance approaches.

Path-Following With LiDAR-Based Obstacle Avoidance of an Unmanned Surface Vehicle in Harbor Conditions

Abstract: This article studies the design, modeling, and implementation challenges of a path-following with obstacle avoidance algorithms as guidance, navigation, and control (GNC) architecture of an unmanned surface vehicle (USV) in harbor conditions. First, an effective mathematical model is developed based on system identification, validating the USV model with field-test data. Then, a guidance system is addressed based on a line-of-sight algorithm, which uses a LiDAR as the main perception sensor for the obstacle avoidance algorithm. The GNC architecture uses a modular approach, including obstacle detection, path-following, and control in the USV platform. Finally, an implementation challenge in two control scenarios, simulation and field test, is addressed to validate the designed GNC architecture.

Sketch2Domino: Interactive Chain Reaction Design and Guidance

Abstract: It is a challenging task for common users to design and arrange the chain reaction with domino blocks In this paper, we propose, Sketch2Domino, an interactive chain reaction design and guidance system with the input of the user freeform sketches The proposed design system converts the captured user sketch into an arrangement graph of domino blocks Then, the system formats the graph into a valid chain reaction and provides visual guidance with interactive projection mapping The guidance system notices the user of the differences among the current blocks and the calculated results This system can support multi-users to complete the chain-reaction design in group collaboration It is verified that Sketch2Domino is convenient and helpful from our case studies

A Review of Training and Guidance Systems in Medical Surgery

Abstract: In this paper, a map of the state of the art of recent medical simulators that provide evaluation and guidance for surgical procedures is performed. The systems are reviewed and compared from the viewpoint of the used technology, force feedback, learning evaluation, didactic and visual aid, guidance, data collection and storage, and type of solution (commercial or non-commercial). The works’ assessment was made to identify if—(1) current applications can provide assistance and track performance in training, and (2) virtual environments are more suitable for practicing than physical applications. Automatic analysis of the papers was performed to minimize subjective bias. It was found that some works limit themselves to recording the session data to evaluate them internally, while others assess it and provide immediate user feedback. However, it was found that few works are currently implementing guidance, aid during sessions, and assessment. Current trends suggest that the evaluation process’s automation could reduce the workload of experts and let them focus on improving the curriculum covered in medical education. Lastly, this paper also draws several conclusions, observations per area, and suggestions for future work.

Towards a unified model-free control architecture for tailsitter micro air vehicles: Flight simulation analysis and experimental flights

Abstract: Hybrid Micro Air Vehicles (MAVs) combine the beneficial features of rotorcraft with fixed-wing configurations providing a complete flight envelope that includes vertical take-off, hover, transitioning flights, forward flight and vertical landing. Tailsitter MAVs belong to a particular class of hybrid MAVs and its peculiar issue is related to the transitioning flight phase where, for high incidence angles, fast changing of aerodynamic forces and moments are observed which are difficult to model and control accurately. To overcome this issue, we proposed a control architecture with model-free control (MFC) algorithms that has been able to stabilize the hybrid MAV's attitude, velocity, and position without any modeling process. The proposed control architecture consisted basically two steps~: 1) The attitude control, to ensure the hybrid MAV's attitude tracking and stability within the entire flight envelope; 2) The guidance system responsible to control both velocity and position. We validated the MFC architecture according to a comprehensive set of flight simulations and experimental flight tests. Experimental flight tests shown an effective and promising control strategy solving the principal issue of hybrid MAVs that was the formulation of accurate hybrid MAV's dynamic equations to design control laws. The obtained results have provided a straightforward way to validate the methodological principles presented in this article as well as to certify the designed MFC parameters, and to establish a conclusion regarding MFC benefits in both theoretical and practical contexts.

Vision-based Guidance and Navigation for Autonomous MAV in Indoor Environment

Abstract: The paper presents an autonomous vision-based guidance and mapping algorithm for navigation of drones in a GPS-denied environment. We propose a novel algorithm that accurately uses OpenCV ArUco markers as a reference for path detection and guidance using a stereo camera. It enables the drone to navigate and map an environment using vision-based path planning. Special attention has been given towards the robustness of guidance and controlling strategy, accuracy in the vehicle pose estimation and real-time operation. The proposed algorithm is evaluated in a 3D simulated environment using ROS and Gazebo. The results have been presented for drone navigation in a maze pattern indoor scenario. Evaluation of the given guidance system in the simulated environment suggests that the proposed system can be used for generating a 2D/3D occupancy grid map autonomously without the use of high-level algorithms and expensive sensors such as lidars.

Guidance for Autonomous Underwater Vehicles in Confined Semistructured Environments

Abstract: In this work, we present the design, implementation, and testing of a guidance system for the UX-1 robot, a novel spherical underwater vehicle designed to explore and map flooded underground mines. For this purpose, it needs to navigate completely autonomously, as no communications are possible, in the 3D networks of tunnels of semistructured but unknown environments and gather various geoscientific data. First, the overall design concepts of the robot are presented. Then, the guidance system and its subsystems are explained. Finally, the system's validation and integration with the rest of the UX-1 robot systems are presented. A series of experimental tests following the software-in-the-loop and the hardware-in-the-loop paradigms have been carried out, designed to simulate as closely as possible navigation in mine tunnel environments. The results obtained in these tests demonstrate the effectiveness of the guidance system and its proper integration with the rest of the systems of the robot, and validate the abilities of the UX-1 platform to perform complex missions in flooded mine environments.

A Co-Operative Autonomous Offshore System for Target Detection Using Multi-Sensor Technology

Abstract: This article studies the design, modeling, and implementation challenges for a target detection algorithm using multi-sensor technology of a co-operative autonomous offshore system, formed by an unmanned surface vehicle (USV) and an autonomous underwater vehicle (AUV). First, the study develops an accurate mathematical model of the USV to be included as a simulation environment for testing the guidance, navigation, and control (GNC) algorithm. Then, a guidance system is addressed based on an underwater coverage path for the AUV, which uses a mechanical imaging sonar as the primary AUV perception sensor and ultra-short baseline (USBL) as a positioning system. Once the target is detected, the AUV sends its location to the USV, which creates a straight-line for path following with obstacle avoidance capabilities, using a LiDAR as the main USV perception sensor. This communication in the co-operative autonomous offshore system includes a decentralized Robot Operating System (ROS) framework with a master node at each vehicle. Additionally, each vehicle uses a modular approach for the GNC architecture, including target detection, path-following, and guidance control modules. Finally, implementation challenges in a field test scenario involving both AUV and USV are addressed to validate the target detection algorithm.

Modeling and analysis of driver behavior under shared control through weighted visual and haptic guidance.

Abstract: For the optimum design of a driver-automation shared control system, an understanding of driver behavior based on measurements and modeling is crucial early in the development process. This paper presents a driver model through a weighting process of visual guidance from the road ahead and haptic guidance from a steering system for a lane-following task. The proposed weighting process describes the interaction of a driver with the haptic guidance steering and the driver reliance on it. A driving simulator experiment is conducted to identify the model parameters for driving manually and with haptic guidance. The proposed driver model matched the driver input torque with a satisfactory goodness of fit among fourteen participants after considering the individual differences. The validation results reveal that the simulated trajectory effectively followed the driving course by matching the measured trajectory, thereby indicating that the proposed driver model is capable of predicting driver behavior during haptic guidance. Furthermore, the effect of different degrees of driver reliance on driving performance is evaluated considering various driver states and with system failure via numerical analysis. The model evaluation results reveal the potential of the proposed driver model to be applied in the design and evaluation of a haptic guidance system.

Optimal Control for Electromagnetic Haptic Guidance Systems

Abstract: We introduce an optimal control method for electromagnetic haptic guidance systems. Our real-time approach assists users in pen-based tasks such as drawing, sketching or designing. The key to our control method is that it guides users, yet does not take away agency. Existing approaches force the stylus to a continuously advancing setpoint on a target trajectory, leading to undesirable behavior such as loss of haptic guidance or unintended snapping. Our control approach, in contrast, gently pulls users towards the target trajectory, allowing them to always easily override the system to adapt their input spontaneously and draw at their own speed. To achieve this flexible guidance, our optimization iteratively predicts the motion of an input device such as a pen, and adjusts the position and strength of an underlying dynamic electromagnetic actuator accordingly. To enable real-time computation, we additionally introduce a novel and fast approximate model of an electromagnet. We demonstrate the applicability of our approach by implementing it on a prototypical hardware platform based on an electromagnet moving on a bi-axial linear stage, as well as a set of applications. Experimental results show that our approach is more accurate and preferred by users compared to open-loop and time-dependent closed-loop approaches.

Design and control of an image-guided robot for spine surgery in a hybrid OR.

Abstract: Background Minimally invasive spine (MIS) fusion surgery requires image guidance and expert manual dexterity for a successful, efficient, and accurate pedicle screw placement. Operating room (OR)-integrated robotic solution can provide precise assistance to potentially minimize complication rates and facilitate difficult MIS procedures. Methods A 5-degrees of freedom robot was designed specifically for a hybrid OR with integrated surgical navigation for guiding pedicle screw pilot holes. The system automatically aligns an instrument following the surgical plan using only instrument tracking feedback. Contrary to commercially available robotic systems, no tracking markers on the robotic arm are required. The system was evaluated in a cadaver study. Results The mean targeting error (N = 34) was 1.27±0.57 mm and 1.62±0.85°, with 100% of insertions graded as clinically acceptable. Conclusions A fully integrated robotic guidance system, including intra-op imaging, planning, and physical guidance with optimized robot design and control, can improve workflow and provide pedicle screw guidance with less than 2 mm targeting error.

MViDO: A High Performance Monocular Vision-Based System for Docking A Hovering AUV

Abstract: This paper presents a high performance (low computationally demanding) monocular vision-based system for a hovering Autonomous Underwater Vehicle (AUV) in the context of autonomous docking process-MViDO system: Monocular Vision-based Docking Operation aid. The MViDO consists of three sub-modules: a pose estimator, a tracker and a guidance sub-module. The system is based on a single camera and a three spherical color markers target that signal the docking station. The MViDO system allows the pose estimation of the three color markers even in situations of temporary occlusions, being also a system that rejects outliers and false detections. This paper also describes the design and implementation of the MViDO guidance module for the docking manoeuvres. We address the problem of driving the AUV to a docking station with the help of the visual markers detected by the on-board camera, and show that by adequately choosing the references for the linear degrees of freedom of the AUV, the AUV is conducted to the dock while keeping those markers in the field of view of the on-board camera. The main concepts behind the MViDO are provided and a complete characterization of the developed system is presented from the formal and experimental point of view. To test and evaluate the MViDO detector and pose an estimator module, we created a ground truth setup. To test and evaluate the tracker module we used the MARES AUV and the designed target in a four-meter tank. The performance of the proposed guidance law was tested on simulink/Matlab.

The feasibility of Follow-the-Greens for 4-dimensional trajectory based airport ground movements

Abstract: Safer and more efficient airport ground movements can be planned by routing and scheduling systems based on the 4-dimensional trajectory (4DT). In order to achieve the benefits envisioned in the planning stage, an effective taxiing guidance system is indispensable. The Follow-the-Greens (FtG) guidance concept provides an augmented means for 4DT based taxiing with pilot in the loop, which is expected to guide the piloted aircraft by dynamically adjusting the lit position of green ground navigation lamps according to the assigned 4DTs. This paper presents a simulation study to investigate the feasibility of FtG based on a control theoretic modeling of the taxiing system. The 4DT conformance errors with different navigation lamp control strategies are investigated. The key performance indices, including temporal constraint violation and fuel consumption, are analysed. The results demonstrate that it is feasible to follow conflict-free 4DTs through FtG if an appropriate lamp controller is available. The results also highlight the need to proactively handle the potential conformance errors in the routing and scheduling stage.

Modelling and Simulation of Missile Guidance in WEBOTS Simulator Environment

Abstract: The article deals with the modelling and simulation (M&S) of missile guidance systems and methods, especially the Line-Of-Sight Beam Riding (LOSBR) guidance and passive homing (PH) guidance in WEBOTS robot simulation environment. The major goal is to evaluate general possibilities and aspects of M&S of missile guidance systems, methods and describe the process of implementation and suitability of WEBOTS simulator. The main focus is on the implementation and functionality verification of launcher, missile and target models. Functionality model includes the essential parts of given guidance system, such as laser beam emitter, photo detectors, IR emitter, range finder, optical sensor and other devices for position settings. Simulation results are verified, evaluated and compared with expected behaviour and mathematical models.

On the Evaluation of Force Feedback Augmented Teleoperation of Excavator-like Mobile Manipulators

Abstract: This paper reports the results of the investigation on the use of force feedback to assist a human operator in the teleoperation of open-pit mining excavators. The proposed force feedback strategy allows object interactions. Also, it enables the operator to sense attractive forces toward the excavation/deposit site as a guidance system, especially useful in precision mining. The methodology was evaluated with multiple experiments to compare the use of haptic feedback and the guidance system. Moreover, a group of volunteers performed the NASA Task Load Index to measure their efforts to teleoperate an integrated off-the-shelf excavator-like mobile robot using different scenarios. Results showed that the force feedback decreases by 8% the power consumption of the excavator, which can represent a significant cost reduction in real applications. Furthermore, the proposed system proves to be a useful tool to the operator allowing task assistance and safety in interaction with obstacles, which can mitigate up to 70% of the stress on the manipulator when there is direct contact with surfaces, e.g., manipulation of rocks and boulders.

GNSS Network RTK for Automatic Guidance in Agriculture: Testing and Performance Evaluation

Abstract: The paper reports the results of a research on validation and optimization of automatic and semi-automatic guidance systems for agricultural machinery based on Real-Time positioning services provided by GNSS Networks (NRTK). The research is based on experimental campaigns performed on test areas, located in Umbria (central Italy) on the land of six farming companies.

Development of a Comfort-Based Motion Guidance System for a Robot Walking Helper

Abstract: In research on providing motion assistance for elderly care, the robot walking helper is considered to be able to maintain their vitality. For its practicality, one issue of interest is its feasible path planning for guidance. Inspired by the concept of including human factors for path planning previously proposed, in this paper, we develop such a motion guidance system for the robot walking helper. We first selected the human factors most vital for the elderly and also public via an Internet survey, and then developed a corresponding path planning algorithm and control strategy for its realization. Experiments are conducted to demonstrate the effectiveness of the proposed system. Key contributions of the paper lie on (a) one of the few studies that include human factors into path planning of the robot walking helper and (b) a more thorough consideration on comfort with both physical and psychological factors corresponding to elderly and public preference included.

A Geometry-Based Guidance Law to Control Impact Time and Angle under Variable Speeds

Abstract: To provide a feasible solution for a variable speed unmanned aerial vehicle (UAV) to home on a target with impact time and angle constraints, this paper presents a novel geometry-based guidance law composed of trajectory reshaping and tracking. A trajectory generation process using Bezier curves is introduced to satisfy the impact time and angle constraints under time-varying speed. The impact angle is satisfied by driving the UAV along a specified ending line. The impact time is satisfied by controlling the trajectory length, which is realized through adjusting one Bezier curve end point along the ending line. The adjustable range of this end point, along with the maximum trajectory curvature, is analyzed to ensure that the trajectory is flyable. Guidance command is generated using inverse dynamics. Numerical simulations under various scenarios are demonstrated to illustrate the performance and validate the effectiveness of the proposed method.

Improved Navigation and Guidance System of AUV Using Sensors Fusion

Abstract: Improved navigation and guidance system of Autonomous Underwater Vehicle (AUV) is a most important assignment for most researchers, specifically in difficult environments such as the ocean. In ocean environment, the AUV needs a reliable navigation and guidance system to navigate and guidance AUV in the desired path with high efficiency. The proposed method for improving navigation system of AUV is based on integrated MEMS smartphone sensors by the collected data from Doppler Velocity Log (DVL), depth, and compass sensors via Loosely Coupled Kalman Filter (KF). The Loosely Coupled KF is used to estimate and correct velocity and attitude errors of AUV navigation system by DVL, depth and compass measurements, respectively. The practice device of AUV is based on Ultrasonic sensors, microcontroller, depth, and digital circuit sensors. The ultrasonic sensor is used to detect boundaries in the route of AUV. The depth sensor is used to dive the AUV in the required depth. The microcontroller and digital circuit are usage to rule the motion and direction of AUV in the required path. The AUV is examined in a testbed at depth of 7 meters from water surface. There are three obstacles are placed in the direction of AUV to check its efficiency. During tests, the AUV is capable to reach the target place with high efficiency. After that, it returned back to the base station accordance to saved direction in its reminiscence with full effectiveness also.