Estimating Critical Latency Affecting Ship’s Collision in Re-mote Maneuvering of Autonomous Ships

Estimation of the critical latency that can cause collision in remote maneuvering of autonomous ships can provide a clue to avoid collisions. The concept of estimating the critical latency was established using the turning circle formed by the turning maneuver of the own ship, and critical latency was estimated using the radius of the turning circle with the turning time ratio. The turning circle was observed using the turning trajectory of the give-way vessel measured in the ship maneuvering simulation experiment. Experimental results demonstrated that the proposed method is capable of identifying both the location and time of the collision due to critical latency. As a result, a clue to avoid possible collision in remote maneuvering caused by critical latency was deduced.

Control Oriented Maneuver Model of Prismatic Planing Hull

Roll yaw coupled dynamics are not well characterized and existing low cost models are limited in range of applicability. We utilize an interpolation based approach to address a wider range of conditions with reduced computational requirements. By interpolating test data to estimate hydrodynamic forces and empirically modeling roll damping and added mass, we establish a 4DOF maneuvering model for prismatic planing hulls in calm water. It is validated against relevant tests and show significant computational resource savings in comparison with potential flow based methods. Simulation of an extreme turning maneuver and an asymmetrical loading case demonstrates its potential for use in initial design, control and evaluation.

Investigation of planing craft maneuverability using full-scale tests

Maneuverability of planing craft is a complicated hydrodynamic subject that needs more studies to comprehend its characteristics. Planing craft drivers follow a common practice for maneuver of the craft that is fundamentally different from ship’s standards. In situ full-scale tests are normally necessary to understand the maneuverability characteristics of planing craft. In this paper, a study has been conducted to illustrate maneuverability characteristics of planing craft by full-scale tests. Accelerating and turning maneuver tests are conducted on two cases at different forward speeds and rudder angles. In each test, dynamic trim, trajectory, speed, roll of the craft are recorded. The tests are performed in planing mode, semi-planing mode, and transition between planing mode to semi-planing mode to study the effects of the craft forward speed and consequently running attitude on the maneuverability. Analysis of the data reveals that the Steady Turning Diameter (STD) of the planing craft may be as large as 40 L, while it rarely goes beyond 5 L for ships. Results also show that a turning maneuver starting at planing mode might end in semi-planing mode. This transition can remarkably improve the performance characteristics of the planing craft’s maneuverability. Therefore, an alternative practice is proposed instead of the classic turning maneuver. In this practice, the craft traveling in the planing mode is transitioned to the semi-planing mode by forward speed reduction first, and then the turning maneuver is executed.

Popov-H∞ Robust Path-Tracking Control of Autonomous Ground Vehicles with Consideration of Sector Bounded Kinematic Nonlinearity

This paper proposes a new approach to cope with the kinematic nonlinearity in the H∞ vehicle path-tracking controller synthesis problem. The kinematic nonlinearity presented in the vehicle lateral error state is found to satisfy the sector-bound condition. By isolating the sector bounded nonlinearity via an upper linear fractional transformation (LFT), a Lur'e system is formulated. A nominal robust controller is synthesized to meet both the Popov-H∞ criterion and the regional pole placement requirement. A polytopic gain-scheduling technique is subsequently employed to accommodate the effect of the varying vehicle longitudinal velocity. Finally, an instant-turning maneuver and a sharp lane-changing maneuver are tested in CarSim-Simulink joint simulations whose results demonstrate the superiority of the proposed Popov-H∞ controller over a conventional H∞ controller.

Drivers’ Psychomotor Reaction Times Tested with a Test Station Method

The article presents the standard method of the evaluation of car drivers’ psychomotor reaction times. A characteristic feature of this method is the ability to conduct tests using real vehicles equipped with mobile measuring apparatus. Measurements are carried out on people whose task is to initiate specific maneuvers (such as: a braking or turning maneuver, a combined braking and turning maneuver, as well as e.g., the use of an audio signal) in response to external stimuli coming from different directions. The sources of the stimuli are light signals emitted by variable message signs placed around the vehicle. The developed control and measurement equipment allows us to realize various and complex test scenarios. It generates stimulus sequences, assesses the correctness of the driver’s response and measures its time. This method allows us to obtain sets of results from tests carried out under different conditions and variable test durations. The possibility of testing a large number of participants in a relatively short time and in repetitive conditions allows for reliable statistical inference. The paper presents examples of research results obtained on the basis of few thousand tests carried out on a large group of respondents. The registered data was statistically processed and referred to the literature. A high degree of correlation between the analyzed results and the literature reports proves that the presented method may be a source of data for the analysis of phenomena related to the time of the driver’s response, especially the influence of various factors affecting its values.

TECHNICAL ANALYSIS OF VEHICLE DRIVERS’ ACTIONS AT UNCONTROLLED INTERSECTIONS WHILE TURNING LEFT

The questions which arise at experts while carrying out road accident analysis (forensic expert examination) during technical analysis of vehicle drivers’ actions at uncontrolled intersections, in cases when turning left at a separating lawn line a traffic sign “Yield” is installed, and a traffic sign “Priority Road” is installed at the intersection facing the direction of vehicle movement which turns left, are considered. When technically evaluating drivers actions at an uncontrolled intersection in accordance with the requirements of Traffic Rules of Ukraine, forensic experts who make up a forensic report on the results of road accident analysis wonder: “How to evaluate the driver’s actions who performs a turning maneuver to the left at uncontrolled intersection, when a traffic sign ‘Yield’ is installed at a separating lawn line while turning left, and a traffic sign “Priority Road” is installed at the intersection facing the direction of vehicle movement where the vehicle turns left. Technical analysis of the driver actions who turns left at an uncontrolled intersection should be carried out in accordance with the requirements of paragraphs 10.1 and 16.13 of Traffic Rules of Ukraine. This is due to the fact that the presence of a traffic sign 2.3 “Priority Road” indicates the fact that a driver is on the priority road, and must give way to vehicles moving in the opposite direction heading straight or right when making a left turn.

Simulation of a Motor Vehicle’s Motion on the Basis of a Turning with the Steering Wheel Release

In this paper, the selected phenomena related to a motor vehicle’s motion have been considered based on a computer simulation in MSC Adams/Car. The vehicle’s model performed a turning maneuver with the steering wheel release under different road conditions.All simulations have been performed based on the sports two-seater vehicle’s model, at the initial speed of 70 km/h on the flat and randomly uneven road. This enabled us to observe the selected phenomena along the road long enough to relate them to different aspects of road traffic safety in unusual situations. For uneven road, the same profiles were assumed for the left and the right wheel of the vehicle, with two coefficient values determining the maximum height of these irregularities.

Effects of Hull and Control Surface Roughness on Ship Maneuvering

The effects of hull roughness on ship maneuvering characteristics are investigated. The hydrodynamic derivatives in the equations of motion for surface vessel maneuvering are modified to incorporate roughness of the hull and rudder. Vessel lifetime roughness profiles are postulated based on construction, coatings, operation, and maintenance for a vessel life of 25 years. These are then applied to the turning maneuver for single screw cargo ships with block coefficients from .60 to .80. The implications for naval missions are discussed.

CFD Simulations and Experiments of a Submarine in Turn, Zigzag, and Surfacing Maneuvers

We present simulations and experiments of the generic submarine Joubert BB2 performing standard turn, zigzag, and surfacing maneuvers in calm water at depth. The free sailing experiments, performed at Maritime Research Institute Netherlands (MARIN), are unique in that they present an open dataset for the community to benchmark maneuvering prediction methodologies. Computations were performed with explicitly gridded sailplanes, tail planes, and propellers using a dynamic overset technique. This study analyzes a 20-degree turning maneuver with vertical control commanding the stern planes and a 20/20 zigzag maneuver with vertical control commanding both sail and stern planes, both of them at a nominal speed of 10 knots, and a 20-degree rise maneuver with horizontal control at 12 knots. The results show that computational fluid dynamics can predict well motions and speeds for free-sailing conditions, but controller commands are harder to replicate. Computations of the rise maneuver with surfacing compare well with experiments, including a crashback maneuver to stop the submarine.