Ground Vehicle Applications Research Articles

Utilization of UGV in Mining Sectors

In various sectors such as defense and mining, existing Unmanned Ground Vehicle (UGV) applications face specific limitations, including the inability to achieve wide- range control and operate in dark environments. To mitigate human risks and reduce human involvement in bomb disposal operations, the need for UGVs has become crucial. In this context, we propose a model/framework that utilizes gas and temperature sensors to detect environmental conditions. Our framework aims to enhance UGV applications by incorporating wide-range Wi-Fi enabled control devices and night mode camera functionality. This enables rapid object detection over a greater distance and emphasizes remote control through a mobile application. As a result, the proposed system automates the process of bomb disposal, thereby reducing human risks involved in such operations.

Stereo visual odometry with velocity constraint for ground vehicle applications

AbstractThis paper proposes a novel method of error mitigation for stereo visual odometry (VO) applied in land vehicles. A non-holonomic constraint (NHC), which imposes physical constraint to the rightward velocity of a land vehicle, is implemented as an observation in an extended Kalman filter (EKF) to reduce the drift of stereo VO. The EKF state vector includes position errors in an Earth-centred, Earth-fixed (ECEF) frame, velocity errors in the camera frame, angular rate errors and attitude errors. All the related equations are described and presented in detail. In this approach, no additional sensors are used but NHC, namely velocity constraint in the right direction , is applied as an external measurement to improve the accuracy. Tests are conducted with the Karlsruhe Institute of Technology and Toyota Technological Institute (KITTI) datasets. Results show that the relative horizontal positioning error improved from 0⋅63% to 0⋅22% on average with the application of the velocity constraints. The maximum and root mean square of the horizontal error with velocity constraints are both reduced to less than half of the error with stand-alone stereo VO.

Implementing cryptography in LoRa based communication devices for unmanned ground vehicle applications

In this study, a Long Range (LoRa) based bidirectional secured communication link for controlling and monitoring the robots from a remote location is proposed. The security features and structure of the LoRa is build upon the standard protocol called LoRa wide area networks (LoRaWAN). To take advantage of these features, LoRa devices/end modules need to be connected to a network server through a LoRa gateway. However, for certain military scenarios like war zones, terrorist attack sites, disaster sites etc., the availability of standard network cannot be guaranteed, and therefore, the security features available with LoRaWAN protocol cannot be guaranteed. To overcome this critical limitation, a LoRa based secured device for establishing a bidirectional communication link between the base station and the robots without relying on any network is proposed. To secure the exchanged data, a cryptographic protocol is developed, and confidentiality, authenticity and integrity of the transmitted data between the base station and the robot are ensured. The protocol is then implemented with a pair of LoRa devices and its functionality is tested from a remote location by controlling and monitoring a Pioneer-P3Dx robot from a distance of 1.2 miles. The test shows that the proposed cryptographic protocol can securely control and track the robot from a remote location.

Modified 1D Virtual Force Field Approach to Moving Obstacle Avoidance for Autonomous Ground Vehicles

A modified 1D-virtual force field (1D-VFF) approach is newly proposed to effectively avoid moving obstacles for autonomous ground vehicle (AGV) applications. The underlying idea of this approach is to construct an obstacle force field based on the predicted trajectory of a moving obstacle. To do this, the time-to-collision and the probable area of collision are estimated using the obstacle position and velocity information measured from a FMCW radar. The predicted obstacle force field (POFF) replaces the obstacle force field (OFF) of the conventional 1D-VFF to enhance the AGV’s obstacle avoidance performance. As in the conventional 1D-VFF scheme, the steering force field (SFF) is generated by using the prescribed position of the goal and the current position of the ground vehicle. In order to ensure a collision-free local path against the moving obstacle, the steering command is determined as the maximizing solution of the integrated force field (IFF) defined by a linear combination of POFF and SFF. Simulations of various scenarios show that the proposed algorithm provides an improved local path planning performance against moving obstacles compared to the existing 1D-VFF methodology.

Experimental analysis of an integrated biomass gasification and PEM fuel cell system

ABSTRACTPEM fuel cell is an electrochemical system that converts the chemical energy of hydrogen directly into electricity and is widely used as an energy source for ground vehicle applications. This paper aims to analyze the technical aspects of integrated biomass gasification and PEM fuel cell systems for electricity production which is focused on gasifier operating conditions and their effect on the cell voltage. To evaluate the effect of gasifier operating conditions (gasification temperature, steam/biomass ratio, equivalence ratio, and biomass particle size) on cell voltage, an experimental work has also been carried. The results show that for all catalysts, the cell voltage increased rapidly as the reaction temperature increased from 500 °C to 650 °C, then tended to a slow growth due to the increase of reaction rates, enabling the fast decomposition of biomass into clean syngas (H2 and CO), especially at the initial stage of reaction.

Description and experimental results of a panoramic K‐band radar dedicated to perception in mobile robotics applications

AbstractRobust environmental perception is a crucial parameter for the development of autonomous ground vehicle applications, especially in the field of agricultural robotics which is one of the priorities for the Horizon 2020 robotics funding (EU funding program for research and innovation). Because of uncontrolled and changing environmental conditions in outdoor and natural environments, data from optical sensors classically used in mobile robotics can be compromised and unusable. In such situations, microwave radar can provide an alternative and complementary solution for perception tasks. The aim of this paper is to present PELICAN radar, a microwave radar specifically designed for mobile robotics applications, including obstacle detection, mapping, and situational awareness in general. PELICAN radar provides each second a view over 360° of the surrounding environment, from 5 m up to 100 m. A description of the technological solutions adopted for the development of PELICAN radar (hardware and software) is presented. Results obtained in various outdoor and open environments, including urban and natural areas, are also described. Sets of PELICAN radar data are made available online for researchers interested in processing this type of data.

Sustainable alternative fuels in aviation

Abstract In recent years, renewable energy resources have become more important due to the limited number of regions for production of petroleum-based fuels, which are continuously depleting. The aviation sector in terms of commercial and cargo transportation has an increasing need for conventional, as well as, alternative fuels. Derivatives of petroleum fuels used in aviation have negative impacts on air quality. Factors causing greenhouse gas emissions (GHG) in the aviation sector must be reduced. However, such fuels used in the aviation sector are not sustainable. Biofuels which have the potential to replace petroleum fuels and help with emissions are heavily investigated in developed countries for independency, creating a better environment and sustainability. Biofuels which are already used for ground vehicles could also be implemented in the aviation sector to reduce fuel cost and emissions. Overall, aviation fuels made of sustainable resources would also support social and economic development. Numerous industrial initiatives have emerged to find alternative ways to attain bio-aviation fuels. Therefore, there is an increasing level of research with regards to alternative aviation fuels made of biomass in recent years. It is important to obtain basic feedstocks and to develop biofuel production processes in a cost-effective way. This study examines the necessity and the types of biofuels in the aviation sector. By designing unique fuel systems for air vehicles, it is possible to formulate biofuels which can be used for both air and ground vehicle applications. This type of consensus would help with sustainability and a better environment.

Low-cycle fatigue behavior of fiber-laser welded, corrosion-resistant, high-strength low alloy sheet steel

Advanced laser welding techniques such as fiber laser welding are desirable for joining high-strength steels in ground vehicle applications since they can greatly increase productivity. Weld fatigue is a primary design consideration for implementation of laser-welded sheet into ground vehicle structures. However, much of the previous fatigue work on fiber laser welded sheet steel has utilized stress-controlled fatigue testing. Therefore, this paper presents an optimized fiber laser welding procedure for butt welds of high-strength low-alloy steel sheet, and subsequent fully-reversed, strain-controlled low-cycle fatigue testing on weld material. Existing low cycle fatigue models adequately describe fatigue behavior of the laser welds. The results show that weld low cycle fatigue strength is significantly increased relative to base metal due to formation of martensite in the weld caused by rapid cooling inherent to laser welding. Weld fatigue life was shorter than base metal when plastic strains were high, but was close to base metal at lower plastic strains. Fatigue specimens containing weld failed at both base metal and in the weld indicating that there is some competition between weld cyclic fatigue strength and stress concentration effect at the weld fusion zone.

Observer-Based Estimation of Aging Condition for Selective Catalytic Reduction Systems in Vehicle Applications

This paper presents two observers for estimating the aging condition of selective catalytic reduction (SCR) systems in vehicle applications. SCR systems have been widely recognized as one of the leading engine exhaust gas aftertreatment systems for reducing diesel powertrain tailpipe NOx emissions in ground vehicle applications. While fresh SCRs are quite effective in reducing tailpipe NOx emissions, their NOx reduction capabilities and performances may substantially degrade with in-service aging. To maintain the emission control performance of a SCR system for a diesel engine during the entire vehicle service life, it is thus critical to have an accurate estimation of the SCR system aging condition. In this paper, two Lyapunov-based observers utilizing the measurements of NOx and ammonia concentrations are analytically developed and verified in simulations for estimating the SCR aging condition. The measurement uncertainty is explicitly considered in the observer design process. A sufficient condition for the boundedness of the estimation error is derived. Simulation results under the US06 test cycle demonstrate the effectiveness of the proposed observers.

PELICAN: Panoramic millimeter-wave radar for perception in mobile robotics applications, Part 1: Principles of FMCW radar and of 2D image construction

Robust environmental perception is a crucial parameter for the development of autonomous ground vehicle applications, especially in the field of agricultural robotics which is one of the priorities for the Horizon 2020 robotics funding (EU funding program for research and innovation). Because of uncontrolled and changing environmental conditions in outdoor and natural environments, data from optical sensors classically used in mobile robotics can be compromised and unusable. In such situations, millimeter-wave radar can provide an alternative and complementary solution for perception tasks. The aim of this paper is to present the PELICAN radar, a millimeter-wave radar specifically designed for mobile robotics applications, including obstacle detection, mapping and situational awareness in general. In this first of a two-part paper, the choice of a frequency-modulated continuous-wave radar is explained and the theoretical elements of this solution are detailed. PELICAN radar is using a rotating fan-beam antenna, and the construction of 2D representations of the surrounding environments with radar data is described through simulation results. The second part of the paper will be devoted for a detailed description of PELICAN radar, as well as experimental results.

Critical assessment of the fatigue performance of additively manufactured Ti–6Al–4V and perspective for future research

To realize the potential benefits of additive manufacturing technology in airframe and ground vehicle applications, the fatigue performance of load bearing additively manufactured materials must be understood. Due to the novelty of this rapidly developing technology, a very limited, yet swiftly evolving literature exists on the topic. Motivated by these two points, we have attempted to catalog and analyze the published fatigue performance data of an additively manufactured alloy of significant technological interest, Ti–6Al–4V. Focusing on uniaxial fatigue performance, we compare to traditionally manufactured Ti–6Al–4V, discussing failure mechanisms, defects, microstructure, and processing parameters. We then attempt to identify key knowledge gaps that must be addressed before AM technology can safely and effectively be employed in critical load bearing applications.

Improving unmanned ground vehicle navigation by exploiting virtual sensors and multisensor fusion

This paper investigates techniques on improving navigation accuracy using multiple sensors mounted on a mobile platform and exploiting the inherent characteristic of a ground vehicle that does not move along the cross-track and off the ground, often termed nonholonomic constraints (NHC) for car-like vehicles that assume no slip or skid. The forward velocity of the vehicle is obtained using a wheel encoder. The 3D velocity vector becomes observable during the normal moving state of the vehicle by using NHC, which produces one virtual sensor. Another virtual sensor is the zero-velocity update (ZVU) condition of the vehicle; when the condition is true, the 3D velocity vector (which is zero) becomes observable. These observables were employed in an extended Kalman filter (EKF) update to limit the growth of inertial navigation system error. We designed an EKF for data fusion of inertial measurement units, global positioning systems (GPS), and motion constraints (i.e., NHC and ZVU). We analyzed the effects of utilizing these constraints on improving navigation accuracy in stationary and dynamic cases. Our proposed navigation suite provides reliable accuracy for unmanned ground vehicle applications in a GPS-denied environment (e.g., forest canopy and urban canyon).

INVESTIGATION STUDIES ON SUB-COOLING OF CRYOGENIC LIQUIDS USING HELIUM INJECTION METHOD

In cryogenic propellants, the sub-cooling of cryogenic propellants contained in tanks is an important and effective method for bringing down the lift-off mass of launch vehicle and thus the performance of the rocket engine is greatly improved. This study presents the technical and experimental studies conducted on cryogenic liquids such as Liquid Oxygen, Liquid Nitrogen and Liquid Hydrogen using helium injection method. The influence of cooled Helium on the degree of sub-cooling and the variation in flow rate of Helium gas admitted are discussed. The experimental and theoretical studies indicate that the sub-cooling technique using helium injection is a very simple method and can be very well adopted in propellant tanks used for ground and launch vehicle applications. The overall cooling effect for rocket application is also discussed. The critical values of the non-dimensional parameters and injected helium temperatures are also estimated.

The impact of inlet flow conditions on the aerodynamic performance of an NACA submerged intake for ground vehicle applications

Results are presented following a series of experimental measurements on a submerged NACA-type intake oriented between −30° and +30° yaw to the free stream in an atmospheric boundary layer wind tunnel at a unit Reynolds number of nominally 1 × 106. The intake was subjected to a range of upstream wall boundary layer conditions, and the mass flow into the intake (as measured by an orifice plate) was monitored to assess the aerodynamic performance. The mass flow data are supported by qualitative flow visualisation within the duct, using a smoke filament illuminated in a laser light sheet in order to gain insight into the flow physics. The intake performance, expressed in terms of a non-dimensional flow momentum coefficient, is seen to degrade both with increasing intake orientation to the free stream (changes of nominally 40% are seen for the angle range tested) and with increasing upstream boundary layer displacement thickness (changes of nominally 30% are seen for the range tested). These data are presented as a graphical carpet plot; it is intended that this is used as a guide to performance prediction in non-aeronautical applications where there are often significant changes in both the local flow direction and the boundary layer thickness. Flow visualisation studies show that the degradation in the intake performance with increasing yaw angle can be attributed to a progressive change in the vortex-pair structure within the intake as the local flow angle is increased. Both an increase in the lateral separation and an increase in the size of the respective vortex cores are considered to act so as to reduce the magnitude of the induced inflow into the intake.

Experimental and Numerical Validation of a Wind Gust Facility

The study of a vehicle moving through a lateral wind gust has always been a difficult task due to the difficulties in granting the right similitude. The facility proposed by Ryan and Dominy has been one of the best options to carry it out. In this approach, a double wind tunnel is used to send a lateral moving gust on a stationary model. Using this idea as a starting point, the ISAE has built a dedicated test bench for lateral wind studies on transient conditions. Experimental work has been carried out by means of time-resolved PIV, aiming at studying the unsteady interpenetration of the two flows coming from each wind tunnel. Meanwhile, a 3D CFD model based on URANS was set up, faithfully reproducing the double wind tunnel. Both the experimental and numerical results are compared, and the evolution of the reproduced wind gust is discussed. Conclusions are finally determined about the validity of this kind of test bench for ground vehicle applications.

Design of Special Purpose off Road Vehicle (SPORV) for Unmanned Ground Vehicle Application

This paper describes the design of a Special Purpose Off Road Vehicle which was developed as the main body for an Unmanned Ground Vehicle. The stringent requirement for off-road capabilities and the need to incorporate a plethora of vision based sensing mechanism was the main design criteria that were fulfilled by the Special Purpose Off Road Vehicle. The Special Purpose Off Road Vehicle is incorporated with a host of actuators, instrumentation and drive circuits, Data Acquisition System and remote communication and control module. The Special Purpose Off Road Vehicle is also equipped with an onboard 2 GHZ Pentium Core 2 Duo Processor Class PC that serves as the main controller when it is operated in the UGV mode. The final prototype unit of the Special Purpose Off Road Vehicle was successfully designed, developed and fabricated according to the set requirement and is used as a research prototype unit at Science and Technology Research Institute for Defence, Ministry Of Defence, Malaysia.

Modelling of Low Velocity Impact of Laminated Composite Substructures

Impact is among the important loading scenario which is required to be addressed for fibre reinforced plastics (FRP) materials in ground or space vehicle applications. The failure behaviour of FRP materials under impact loading is a complex process and a detailed analysis of various mode of failure is necessary. In this paper the failure behaviour of laminated carbon fibre reinforced plastic (CFRP) composite structures under impact loading is investigated by conducting numerical simulations using the explicit finite element analysis ANSYS LS-DYNA software [1]. The impact responses and failure behaviours are being investigated by performing a parametric study and sensitivity analysis in which impact velocity, number of plies, incident angle, friction between contacted surfaces, impactor mass and the geometry are varied in separate cases. The FE model is validated by comparing the numerical results with other published results and good correlations are achieved.

Interpolation methods for high-fidelity three-dimensional terrain surfaces

Recent developments in high-fidelity three-dimensional terrain surface measurements have necessitated the development of interpolation methods that are specific to different ground vehicle applications. The objective of this work is the development of application-dependent methods to convert non-uniformly spaced data to uniformly spaced data. This work develops techniques for applying interpolation methods to on-road and off-road terrain surfaces that are used in vehicle simulations. The interpolation methods examined to create uniformly spaced terrain surfaces are mean, median, Inverse Distance to a Power, and Kriging. Each method is judged in four areas: computational efficiency, outlier sensitivity, location sensitivity, and trend sensitivity. The results of this work show that for applications where the resolution of interest is coarse (25 mm or greater) the mean and median are advantageous for creating a uniform grid; but for data applications where fine resolution is required (less than 25 mm) the Inverse Distance to a Power and Kriging have advantages.

The virtual wall approach to limit cycle avoidance for unmanned ground vehicles

Robot Navigation in unknown and very cluttered environments constitutes one of the key challenges in unmanned ground vehicle (UGV) applications. Navigational limit cycles can occur when navigating (UGVs) using behavior-based or other reactive algorithms. Limit cycles occur when the robot is navigating towards the goal but enters an enclosure that has its opening in a direction opposite to the goal. The robot then becomes effectively trapped in the enclosure. This paper presents a solution named the Virtual Wall Approach (VWA) to the limit cycle problem for robot navigation in very cluttered environments. This algorithm is composed of three stages: detection, retraction, and avoidance. The detection stage uses spatial memory to identify the limit cycle. Once the limit cycle has been identified, a labeling operator is applied to a local map of the obstacle field to identify the obstacle or group of obstacles that are causing the deadlock enclosure. The retraction stage defines a waypoint for the robot outside the deadlock area. When the robot crosses the boundary of the deadlock enclosure, a virtual wall is placed near the endpoints of the enclosure to designate this area as off-limits. Finally, the robot activates a virtual sensor so that it can proceed to its original goal, avoiding the virtual wall and obstacles found on its way. Simulations, experiments, and analysis of the VWA implemented on top of a preference-based fuzzy behavior system demonstrate the effectiveness of the proposed method.

Visual odometry for ground vehicle applications

AbstractWe present a system that estimates the motion of a stereo head, or a single moving camera, based on video input. The system operates in real time with low delay, and the motion estimates are used for navigational purposes. The front end of the system is a feature tracker. Point features are matched between pairs of frames and linked into image trajectories at video rate. Robust estimates of the camera motion are then produced from the feature tracks using a geometric hypothesize‐and‐test architecture. This generates motion estimates from visual input alone. No prior knowledge of the scene or the motion is necessary. The visual estimates can also be used in conjunction with information from other sources, such as a global positioning system, inertia sensors, wheel encoders, etc. The pose estimation method has been applied successfully to video from aerial, automotive, and handheld platforms. We focus on results obtained with a stereo head mounted on an autonomous ground vehicle. We give examples of camera trajectories estimated in real time purely from images over previously unseen distances (600 m) and periods of time. © 2006 Wiley Periodicals, Inc.