Vehicle Autonomy Research Articles

UAV APPLICATION IN POST – SEISMIC ENVIRONMENT

Abstract. On April 6, 2009, an earthquake of 6.3 magnitude struck central Italy with its epicentre near L'Aquila, at 42.3502° N, 13.3762° E. The earthquake damaged 3000 to 11 000 buildings in the medieval city of L'Aquila. Several buildings totally collapsed, 308 people were killed. The post emergency phase till now is just at its beginning step. Conventional surveying techniques using high precision total stations, GNSS receivers and laser scanners for investigations on damaged buildings are always becoming more automated, accurate and operative and even much more fast. Even if these techniques represent instruments of extreme operability there are still many evident limits on their use, especially regarding the survey of both the roofs and the facades of tall buildings or dangerous places, typical on post earthquake situations. So using micro UAVs for surveying in such particular cases, many of these problems can be easily bypassed. In fact, the present work aims on experimenting using multi-rotor micro UAVs, that will allow high quality image capturing on roofs and facades of structures in the old city center of L'Aquila. To obtain actual stereoscopic acquisitions of buildings some conditions on the geometry of acquisition have to be observed, for this reason, taking as a guideline classic flight photogrammetric, a flight planning software was developed. Accurate planning for UAVs acquisitions is very important also considering the reduced autonomy of such vehicles. This can be a strategic point if we want to use UAVs for early damage assessment and also for post event reconstruction planning.

Application of Magnetocaloric Heat Pumps in Mobile Air-Conditioning

Air-conditioning (AC) is an important sub-system in electric vehicles (EVs). AC is responsible for the highest energy consumption among all the auxiliary systems. As the energy is delivered by the batteries, the power consumption for air-conditioning can imply a significant reduction of the vehicle autonomy. Given the actual state of the art and the temperature and power requirements, electrically driven compressors are the most feasible solution. However, vapour-compression systems are reaching their maximum efficiency. Using innovative technologies can improve the performance of standard systems and hereby increase the vehicle autonomy. This paper presents the first steps in the design of a magnetocaloric air-conditioner for an electric minibus. The system will include two reversible magnetocaloric heat pumps, one in the front part of a minibus and one on the rear. The heat rejection system of the power electronics will be coupled to the air-conditioning system. In order to assist the design of the system, a dynamic model has been developed for the cabin, the hydraulic loops and heat exchangers, and the magnetocaloric units. An integrated design of the complete system is necessary, as it will work under dynamic conditions which depend on the thermal load in the cabin. In this paper, the operation conditions of the magnetocaloric units are presented and the design of the magnetocaloric air-conditioner is discussed. This work has been developed under the frame of the European Project ICE which aims to develop an innovative mobile air-conditioning system for EVs based on a magnetocaloric heat pump.

Jacobian Task Priority-based Approach for Path Following of Unmanned Surface Vehicles

As marine robotics becomes more and more effective and useful for many real applications, control techniques too must be gradually enhanced in order to answer to the arising need of full autonomy for such vehicles. Hence more advanced control algorithms are currently under-development in the marine robotics community in order to accomplish many tasks with more robustness and reliability. In particular, the present work addresses the path following problem, applying the control paradigm of prioritized tasks, usually exploited for robotic manipulators. Such a technique, besides allowing to keep separate the different tasks, thus getting an “emergent behavior” for the vehicle, also provides the ability to easily add further control tasks without changing the architecture. In the present paper the case of two simple tasks allowing the completion of a path following mission, as well as the vehicle velocity regulation, is dealt with and some simulative results are described.

The Concept of the Modularized Subsystem Performing Mobile Platform Navigation Tasks

Abstract Robotic vehicles autonomy is the subject of many researches performed by various institutions. There is growing tendency to conduct research in the field of autonomous mobile units, unmanned vehicles and robots moving without operator supervision. Authors of this article presents the concept of the modularized subsystem implementing the functionality of the mobile platform navigation in an unknown environment. The concept has been implemented in the real mobile robot.

Control, navigation and collision avoidance for an unmanned aerial vehicle

This article reports the development of an unmanned aerial vehicle capable of attitude estimation and stabilization through the implementation of a nonlinear complementary filter and proportional-integral rate controllers. Four infra-red sensors and an ultrasonic sensor are integrated with the main platform for the collision avoidance schemes and for altitude control, respectively. Critical mission capabilities for the vehicle such as altitude hold and collision avoidance are developed. An outdoor navigation scheme and collision avoidance algorithms are also proposed to enhance the vehicle autonomy. Experimental results have shown that the implemented attitude and altitude controllers are effective and the platform is capable of navigating autonomously with user-defined waypoints. The collision avoidance algorithms allow the platform to avoid obstacles, both reactively and in the midst of navigation routines.

A review on improving the autonomy of unmanned surface vehicles through intelligent collision avoidance manoeuvres

In recent years unmanned vehicles have grown in popularity, with an ever increasing number of applications in industry, the military and research within air, ground and marine domains. In particular, the challenges posed by unmanned marine vehicles in order to increase the level of autonomy include automatic obstacle avoidance and conformance with the Rules of the Road when navigating in the presence of other maritime traffic. The USV Master Plan which has been established for the US Navy outlines a list of objectives for improving autonomy in order to increase mission diversity and reduce the amount of supervisory intervention. This paper addresses the specific development needs based on notable research carried out to date, primarily with regard to navigation, guidance, control and motion planning. The integration of the International Regulations for Avoiding Collisions at Sea within the obstacle avoidance protocols seeks to prevent maritime accidents attributed to human error. The addition of these critical safety measures may be key to a future growth in demand for USVs, as they serve to pave the way for establishing legal policies for unmanned vessels.

Guided Attention For Autonomous System Supervision

Significant increases in automation and vehicle autonomy are expected to transform today’s operators of single unmanned vehicles performing single missions into tomorrow’s supervisors of multiple autonomous systems performing multiple missions. What displays and tools will those future supervisors require, given that they will manage automation that is deterministic and brittle in the dynamic and unpredictable battlespaces of the future? To help mitigate the shortfalls of automation for the future supervisor, we focus on how to make the scope of the events handled by automation explicit to the supervisor. Here, we explore the highlighting of different event attributes, including scope, to guide attention during supervision, and we investigate aspects of geospatial integration and tradeoffs in how the highlighting is applied. These concepts are developed and applied in the domain of unmanned aerial vehicles (UAVs) guided by path planning automation-mediated routes. In a study, participants monitored multiple concurrent missions, and triaged events varying in severity and automation scope, to decide when to intervene. Four different methods of guiding attention were contrasted. Events were (1) in a callout separated from a map, (2) integrated into the map, (3) map-integrated and categorized by priority but not task-tailorable, or (4) map-integrated, categorized, and task- tailorable. Monitoring was fastest and most accurate for categorized and tailorable events, validating the utility of the attentional guidance. These two conditions traded off in the support they provided, however. Monitoring was significantly faster for tailorable vs. categorized events; however, a significant time cost for correctly configuring the tailorable guidance reduced its advantage. This study validates a novel approach for conveying automation scope, and elucidates the need to design and validate new concepts for the specific task needs of the future autonomous systems supervisor.

Adaptive Analytic Hierarchy Process-Based Decision Making to Enhance Vehicle Autonomy

In this paper, an autonomous vehicle function management methodology is studied. At the decision-making level, the proposed system chooses the optimal function [adaptive cruise control (ACC) or a lane change maneuver (LCM)] that is consistent with the user-selected driving mode, such as fast travel, cautious driving, and efficient travel mode, whereas the control level is implemented via a neuromorphic strategy based on the brain limbic system. To realize the decision-making strategy, the analytic hierarchy process (AHP) is used by considering driving safety, traffic flow, and fuel efficiency as objectives, while LCM and ACC are chosen as the alternative functions. The adaptive AHP is further suggested to cope with the dynamically changing traffic environment. The proposed adaptive AHP algorithm provides an optimal relative importance matrix that is essential to making decisions under varying traffic situations and driving modes. The simulation results show that the proposed structure produces an effective approach to autonomous vehicle function management.

Multiresolution Motion Planning for Autonomous Agents via Wavelet-Based Cell Decompositions

We present a path- and motion-planning scheme that is "multiresolution" both in the sense of representing the environment with high accuracy only locally and in the sense of addressing the vehicle kinematic and dynamic constraints only locally. The proposed scheme uses rectangular multiresolution cell decompositions, efficiently generated using the wavelet transform. The wavelet transform is widely used in signal and image processing, with emerging applications in autonomous sensing and perception systems. The proposed motion planner enables the simultaneous use of the wavelet transform in both the perception and in the motion-planning layers of vehicle autonomy, thus potentially reducing online computations. We rigorously prove the completeness of the proposed path-planning scheme, and we provide numerical simulation results to illustrate its efficacy.

Development of an autonomous vehicle highway merging strategy

In this paper, we propose a highway merging method to enhance vehicle autonomy in the highway travelling. The proposed decision making algorithm includes a Modified Intelligent Driver Model (MIDM) based vehicle distance adjustment and path prediction for collision avoidance. In order to maximise the safety and driving efficiency, a time optimal target is selected when the front and rear gap conditions that secure the merging safety are not satisfied. The suggested algorithm is implemented by a lane change manoeuvre and Adaptive Cruise Control (ACC) that are based on a control strategy inspired by the brain limbic system. In order to demonstrate the performance of the suggested merging strategy, the concept of Level of Service (LOS) is utilised in the simulations.

Effect of controller coefficients and converter switching frequency on performance and efficiency of electric drives used in electrical vehicles

The aim of this paper is to analyse the influence of some parameters related with the motors used in electrical vehicles, mainly permanent magnet synchronous and induction motors. The main objective is to minimise the losses in order to increase the vehicle autonomy. In this work, the attention is focused on the selection of the speed controller coefficients and its impact in total losses, using for this analysis the motor speed-torque trajectories. Moreover, the dependency of the switching frequency over the total losses in the motor-converter device is shown. The analysis determines the optimum value for the switching frequency and the results are compared with commercial drives.

Adaptive autonomous underwater vehicles for littoral surveillance

Autonomous underwater vehicles (AUVs) have gained more interest in recent years for military as well as civilian applications. One potential application of AUVs is for the purpose of undersea surveillance. As research into undersea surveillance using AUVs progresses, issues arise as to how an AUV acquires, acts on, and shares information about the undersea battle space. These issues naturally touch on aspects of vehicle autonomy and underwater communications, and need to be resolved through a spiral development process that includes at sea experimentation. This paper presents a recent AUV implementation for active anti-submarine warfare tested at sea in the summer of 2010. On-board signal processing capabilities and an adaptive behavior are discussed in both a simulation and experimental context. The implications for underwater surveillance using AUVs are discussed.

Special issue on Marine Vehicle Autonomy

Special issue on Marine Vehicle Autonomy

Towards unmanned systems for dismounted operations in the Canadian Forces

Unmanned systems are designed to reduce risk and magnify the impact of manned forces. Expanding unmanned involvement in military operations will require greater vehicle autonomy and the adoption of new concepts of operations. This paper discusses the technical challenges of unmanned systems in support of dismounted operations and research efforts by Defence R&D Canada to support unmanned vehicles in this role. New projects have been formulated to address these technical challenges.

UAV Consumable Replenishment: Design Concepts for Automated Service Stations

A key requirement for the complete autonomy of an unmanned aerial vehicle (UAV) is the replenishment of its energy source and other consumables. Such processes are typically overseen and conducted by a human operator, may be time consuming and effectively reduce the operating range of the system. To satisfy the requirements of UAV customers such as military surveillance networks, that seek faster, broader and more fully autonomous systems, and hobbyists, who seek to avoid the hassle associated with changing the fuel source, we develop automated energy recharging systems. Focusing on battery operated remote control helicopters, we employ the Axiomatic Design methodology to develop design concepts of platforms to act as automatic service stations. We propose three station designs for refilling platforms and one concept for battery exchange platforms. In addition, we analyze the economic feasibility of automatic consumable replenishment stations, consider two types of station (container refilling and container exchange) and discuss the application of these systems. Refilling platforms better suit low coverage unmanned aerial systems (UAS) while exchange stations allow high coverage with fewer UAVs.

Nested autonomy for unmanned marine vehicles with MOOS‐IvP

AbstractThis document describes the MOOS‐IvP autonomy software for unmanned marine vehicles and its use in large‐scale ocean sensing systems. MOOS‐IvP is composed of two open‐source software projects funded by the Office of Naval Research. MOOS provides a core autonomy middleware capability, and the MOOS project additionally provides a set of ubiquitous infrastructure utilities. The IvP Helm is the primary component of an additional set of capabilities implemented to form a full marine autonomy suite known as MOOS‐IvP. This software and architecture are platform and mission agnostic and allow for a scalable nesting of unmanned vehicle nodes to form large‐scale, long‐endurance ocean sensing systems composed of heterogeneous platform types with varying degrees of communications connectivity, bandwidth, and latency. © 2010 Wiley Periodicals, Inc.

Improving autonomy and control of autonomous surface vehicles in port protection and mine countermeasure scenarios

AbstractRecent experimentation with autonomous surface vehicles (ASVs) has focused on the use of such platforms to perform tasks of classification or identification of objects first discovered by another sensor. The ASV generally carries small sensors capable of high‐resolution imaging, but only at relatively short ranges. Reacquisition of a contact is inherent in the problem of classification and involves positioning of the surface vehicle with good precision such that the object of interest is in the field of view of the sensors aboard the ASV. This critical task of positioning the vehicle such that the classification sensors can be effectively brought to bear is the primary goal of our autonomy development. Experimental results from a variety of sensors are presented, but the most important in our present work has been a high‐resolution multibeam imaging sonar operating at 450 kHz. This sensor has been successfully used to image divers and bottom objects, with telemetry data sent back to shore via wireless LAN. Although classification was done by a human operator ashore, the vehicle has the capability to keep an object in view of the sensor, representing an important operational advantage of the autonomy. Future work could expand the role of the unmanned platform to deployment of effectors—warning devices or entanglement devices in the case of harbor protection missions or neutralization devices in the case of countermine operations. © 2010 Wiley Periodicals, Inc.

Robust Fault Diagnosis for Atmospheric Reentry Vehicles: A Case Study

This paper deals with the design of robust model-based fault detection and isolation (FDI) systems for atmospheric reentry vehicles. This work draws expertise from actions undertaken within a project at the European level, which develops a collaborative effort between the University of Bordeaux, the European Space Agency, and European Aeronautic Defence and Space Company Astrium on innovative and robust strategies for reusable launch vehicles (RLVs) autonomy. Using an <formula formulatype="inline" xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex Notation="TeX">${\cal H}_{\infty}/{\cal H}_{-}$</tex> </formula> setting, a robust residual-based scheme is developed to diagnose faults on the vehicle wing-flap actuators. This design stage is followed by an original and specific diagnosis-oriented analysis phase based on the calculation of the generalized structured singular value. The latter provides a necessary and sufficient condition for robustness and FDI fault sensitivity over the whole vehicle flight trajectory. A key feature of the proposed approach is that the coupling between the in-plane and out-of-plane vehicle motions, as well as the effects that faults could have on the guidance, navigation, and control performances, are explicitly taken into account within the design procedure. The faulty situations are selected by a prior trimmability analysis to determine those for which the remaining healthy control effectors are able to maintain the vehicle around its center of gravity. Finally, some performance indicators including detection time, required onboard computational effort, and CPU time consumption are assessed and discussed. Simulation results are based on a nonlinear benchmark of the HL-20 vehicle under realistic operational conditions during the autolanding phase. The Monte Carlo results are quite encouraging, illustrating clearly the effectiveness of the proposed technique and suggesting that this solution could be considered as a viable candidate for future RLV programs.

On Evaluation of Robust Autonomy for Uninhabited Vehicles and Systems

This paper discusses a method to quantify robust autonomy of Uninhabited Vehicles and Systems (UVS) in aerospace, marine, or land applications. Based on mission-vehicle specific performance criteria, we define an system utility function that can be evaluated using simulation scenarios for an envelope of environmental conditions. The results of these evaluations are used to compute a figure of merit or measure for operational effectiveness (MOE). The procedure is then augmented to consider faults and the performance of mechanisms to handle these faulty operational modes. This leads to a measure of robust autonomy (MRA). The objective of the proposed figures of merit is to assist in decision making about vehicle performance and reliability at both vehicle development stage (using simulation models) and at certification stage (using hardware-in-the-loop testing). Performance indices based on dynamic and geometric tasks associated with vehicle manoeuvring problems are proposed, and an example of a two-dimensional fly scenario is provided to illustrate the use of the proposed figures of merit.

Increasing underwater vehicle autonomy by reducing energy consumption

In this paper, we concern ourselves with finding a control strategy that minimizes energy consumption along a trajectory connecting two given configurations. We develop an algorithm, based on our previous work with the time optimal problem, which provides implementable control strategies that are energy efficient. We find an interesting correlation between the duration of these trajectories and the optimal duration. We present the algorithm, control strategy and experimental results from our test-bed vehicle.