Browse Topic: Terrain

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4D Conformal Pilot Cueing for Rotorcraft Army Operational ScenariosF-0080-2024-13765/7/2024
Army rotorcraft operations demand precision and adaptability to navigate challenging terrain, respond to real-time mission requirements, and ensure time-to-target arrival. Navigating complex terrain, making real-time trajectory adjustments, and ensuring timely arrival at designated objectives while considering other problems are challenging. This paper focuses on the concept of 4D conformal pilot cueing that can facilitate a significant reduction in pilot workload. To enhance the rotorcraft operations with Army scenarios, a visual cueing method based on Tau Theory for obstacle avoidance is proposed so that the pilot can make a coordinated turn away from the obstacle and safely change the helicopter's trajectory to avoid the collision. To demonstrate the visual cueing method, desktop simulations are performed in Matlab/Simulink environment using simulated pilots.
Kwon, Jeanine, Feigh, Karen, Prasad, JVR, Tauro-Padival, Rahul, Cansu, Ceren
Effects of Sloped Terrain on In-Ground-Effect Hover Performance for an Isolated RotorF-0079-2023-181785/16/2023
ABSTRACT
Prewitt, Jack, Tritschler, John, Milluzzo, Joseph
Iterative Dynamic Programming Based Model Predictive Control of Energy Efficient Cruising for Electric Vehicle with Terrain Preview2020-01-01324/14/2020
As a global optimization method, dynamic programming (DP) can be employed to seek the optimal velocity with minimum energy consumption for EV on given driving cycles. Due to its terrible computational burden, conventional DP is not suitable for real-time implementation especially with higher dimensions. In this paper, we propose an iterative dynamic programming (IDP) approach to reduce computing time firstly. The IDP can obtain the optimal control laws alike the conventional DP by converging the optimal control strategy iteratively and save considerable computing time. Second, the developed IDP and model predictive control (MPC) are combined to establish a real-time cruising controller called IDP-MPC for an EV with terrain preview. In the predictive controller, we use the IDP to solve a constrained finite horizon nonlinear optimization problem. Finally, to assess the performance of the proposed cruising controller, simulation on a realistic urban expressway road terrain is implemented. Energy-saving potential of the IDP-MPC controller is explored by comparing to DP and constant speed (CS) cruising controllers. The comparative study indicates that the IDP-MPC controller can obtain near-optimal energy-saving capacity compared to DP controller.
Ju, Fei, Zhuang, Weichao, Wang, Liangmo, Wang, Qun
An Alternative Forcing Function for Identifying Pilot Frequency Response Using a Series of MesasF-0075-2019-145615/13/2019
The command inputs selected for system identification (SYSID) are dictated by numerous factors, some of which include: 1) The frequency range of interest; 2) The capability of the system to sustain the inputs; 3) The capability of the system to remain ‘agnostic’ to future inputs. When the elements comprising, the system being identified are all electro-mechanical, frequency sweeps, sum-of-sines, and impulsive inputs are standard identification techniques. However, when human manual control becomes an element of the system, the second and third factors are key considerations. Sum-of-sines (SOS) has been used extensively for identifying human control dynamics as it provides an input that is perceived by the pilot as random and focuses power at discrete frequencies. A disadvantage of SOS is the attentional demand it requires from the human operator, which limits the duration of an identification run to typically around one minute. This in turn constrains the lowest frequencies that can be identified, and multiple consecutive runs can lead to operator fatigue and performance degradation. Discrete inputs such as ramps have been employed with human-in-loop testing, but only with regard to Handling Qualities and performance testing. This work examines discrete inputs as a method for human-in-loop SYSID. An experiment was conducted using two terrain profiles: 1) Pop-up (POP), where four mesas (hills) of varying height, slope, and plateau length were unevenly spaced on flat terrain; 2) Sum-of-sines (SOS), where the terrain was comprised of the sum of eleven non-harmonically-related sine waves, so that the contour was perceived as varying randomly. The task for both terrain types was to maintain 20 feet above the ground using pitch (airspeed was fixed at 35 knots) for each run. Bedford workload ratings were collected after each run. Both terrain profiles produced approximately the same open-loop frequency responses, and their coherences were not significantly different. However, the Bedford ratings showed the POP profile was significantly easier to execute than SOS. The POP technique thus presents a less demanding, more appealing, and potentially more consistent way for eliciting frequency information relating to pilot gain, stability, and time delay.
Bachelder, Edward
Design and Conduct of a Flight Test to Investigate Hover In-Ground-Effect Performance over Sloped TerrainF-0075-2019-147355/13/2019
This paper presents flight test results from a research investigation into the effect of sloping terrain on hover power required. The investigation involved flight test data that were collected for a UH-72A Lakota helicopter while hovering inside ground effect above sloped terrain of varied gradients, in several aircraft orientations and multiple heights above the ground. Performance data were collected over a range of thrust coefficients by varying aircraft weight, rotor speed and environmental conditions over two sorties. The data are compared and contrasted to provide specific insight into the effects of slope magnitude, slope orientation, and rotor hub height. The results demonstrate that hovering over sloping terrain yields performance effects that are both non-intuitive and operationally significant. In particular, the effect of the sloping terrain was seen, in some conditions, to cause power requirements that exceed those for hover out-of-ground-effect, a traditional worst-case value for pre-mission performance planning.
Holder, John, Tritschler, John
All-Terrain WheelchairTBMG-290556/1/2018
Researchers have developed an innovative design for a wheelchair that can more easily navigate on soft and uneven outdoor terrain such as grass and gravel. The chair uses three wheels — two wheels in the front (approximately the same size as the rear wheels on a traditional four-wheeled chair), and a third wheel in the back that is roughly two-thirds as tall as the front wheels.
Multimodal Cueing and Assessment of Pilot Engagement During Low Level FlightF-0074-2018-127475/14/2018
ABSTRACT Low-level flight missions can be complex, at times requiring any or all of the following: maneuvering and navigating over challenging terrain, scanning for hostile or friendly units, operation in degraded visibility, radio communications, and decision-making in uncertain and dynamics environments. These conditions, and time, will affect mental workload (MWL) and performance. While direct performance measurements are normally available, information on pilot workload must either be obtained through (intrusive) subjective measures directly from the pilot, or inferred using indirect measurements. Performance can affect MWL, and MWL can affect performance - as the pilot generally perceives and responds to task performance through display interfaces, these displays can be used to manage and balance the tradeoff between MWL and performance. This paper presents the work of a collaborative project between US and Israel whose objectives are to develop a multimodal integrated cueing environment for near-earth helicopter operations, and to validate measures for assessing pilot workload for real-time and post-mission applications. A first simulation experiment was conducted that examined 1) visual cueing depicting both predicted terrain slope and aircraft height-above-ground, and 2) spatial (3D) auditory cueing for depicting predicted deviation from desired height-above-ground and impending collision with terrain. Collected Measures included altitude error, control rate and Bedford rating. Initial results indicate that synergistic visual and auditory cueing can enhance performance, therefore could be used to reduce pilot workload while sustaining performance. A second simulation experiment was designed to assess MWL and task engagement under different workload levels encountered during a low-level mission that included the following conditions: unlimited vs. degraded visibility, presence or absence of obstacles and/or targets and terrain difficulty. Two local measures of workload were favored over a global measure: (1) oculomotor behavior, including the Index of Cognitive Activity (ICA) and (2) pilot's momentary behavior (micro-performance). Preliminary results show promise for using some of these measures as real-time indicators of pilot workload and engagement. The results of these two experiments will provide a framework for the development and evaluation of future workload-adaptive multimodal display concepts for helicopter operations during low-level flight.
Bachelder, E., Godfroy-Cooper, M., Kahana, A., Rottem-Hovev, M., Miller, J.D.
Sound Diffraction Modeling of Rotorcraft Noise Around TerrainF-0073-2017-122795/9/2017
ABSTRACT A new computational technique, Wave Confinement (WC), is extended here to account for sound diffraction around arbitrary terrain. While diffraction around elementary scattering objects, such as a knife edge, single slit, disc, sphere, etc. has been studied for several decades, realistic environments still pose significant problems. This new technique is first validated against Sommerfeld's classical problem of diffraction due to a knife edge. This is followed by comparisons with diffraction over three-dimensional smooth obstacles, such as a disc and Gaussian hill. Finally, comparisons with flight test acoustics data measured behind a hill are also shown. Comparison between experiment and Wave Confinement prediction demonstrates that a Poisson spot occurred behind the isolated hill, resulting in significantly increased sound intensity near the center of the shadowed region.
Stephenson, James, Chitta, Subhashini, Sim, Ben, Steinhoff, John
Degraded Visual Environment Operational LevelsF-0073-2017-120435/9/2017
ABSTRACT The original abstract was titled "Degraded Visual Environment Categories" and in the process of performing the work, it was determined that "Operational Level" was a more relevant term than "category", hence the title change. Degraded Visual Environment (DVE) is a complex topic and not all aircraft or rotorcraft have the same mission or same DVE requirements. While this paper is not assuming a clean sheet of paper approach to defining the problem, it attempts to provide a different view of the problem in the context of Army Attack and Reconnaissance aircraft. The intent is to create a frame work in which the problem can be broken up into smaller pieces using operational contexts that are defined within this paper as operational levels based on visibility and terrain flight levels for Attack aircraft operations under DVE conditions. The objective is to define the problem so that a worst-case problem does not have to be solved first. This is important, because for the near-term, identifying a practical worst-case solution would be unlikely, and without the complete operational context, it would not be as obvious what solutions could provide interim value.
Fenley, Stephen, Graham, Daniel, Gideonse, Rick
Ride Analysis under a Random Road Model with Interval Parameters2017-01-04153/28/2017
This work is motivated by the fact that the surface of a terrain may vary with local pavement properties and number of passes of the vehicle, which means the roughness coefficient and waviness of the terrain may vary in specific intervals. However, in traditional random terrain models, the roughness coefficient and waviness of the terrain are assumed as constants. Therefore, this assumption may be not very reasonable. A novel random terrain model is presented where the roughness coefficient and waviness of the terrain are expressed by interval numbers instead of constants. A 5-degree-of-freedom ride dynamic model of the vehicle with uncertain parameters is derived. The power spectral density (PSD) and root mean square value (RMS) of the vehicle ride responses are shown and analyzed. Analysis results indicate that the vehicle responses vary in specific intervals under the random terrain excitation with interval parameters.
Feng, Xingxing, Xu, Peijun, Fu, Penglei, Zhang, Yunqing
Off-Road Tire-Terrain Interaction: An Analytical Solution2016-01-80299/27/2016
A novel semi-analytical solution has been developed for the calculation of the static and dynamic response of an off road tire interacting with a deformable terrain, which utilizes soil parameters independent of the size of the contact patch (size-independent). The models involved in the solution presented, can be categorized in rigid and/or pneumatic tires, with or without tread pattern. After a concise literature review of related methods, a detailed presentation of the semi-analytical solution is presented, along with assumptions and limitations. A flowchart is provided, showing the main steps of the numerical implementation, and various test cases have been examined, characterized in terms of vertical load, tire dimensions, soil properties, deformability of the tire, and tread pattern. It has been found that the proposed model can qualitatively capture the response of a rolling wheel on deformable terrain.
Papazafeiropoulos, George, Prins, Jan, Bekakos, Chrysostomos-Alexandros, O'Boy, Dan J., Mavros, George
Aerospace & Defense Technology: August 201616AERP088/1/2016
Seeing the Light Achieving Full-Color, Day or Night Readability for Flat-Panel Displays Multiple Node Networking Using PCIe Interconnects PCI Express (PCIe) interconnects, and how they can be used to support multiple node low latency data transfers over copper or optical cables, is gaining momentum in embedded computing solutions. Zero-Emissions Electric Aircraft Theory vs Reality Analyzing Radar Signals With Demodulation Combining Software and Hardware for Highly Specialized Multichannel Spectrum Monitoring Advanced Thermal Management Solutions Thermoelectric Cooling Thermal Ground Planes Thermal Management of Laser Diodes The Effect of Substrate Emissivity on the Spectral Emission of a Hot-Gas Overlayer Process Approach to Determining Quality Inspection Deployment Experimental Setup to Assess Blast and Penetration-Induced Secondary Debris in a Military Operations in Urban Terrain (MOUT) Environment Non-Contact Circuit for Real-Time Electric and Magnetic Field Measurements
Terrain and Obstacle Avoidance Displays for Low-Level Helicopter Operations in Degraded Visual environmentsF-0072-2016-114225/17/2016
Collision with obstacles (typically wires and towers) and with terrain during low level helicopter flight under low visibility conditions has been a documented problem for the US military. Degraded visual environments (DVE) due to night operations and/or poor weather prevent adequate visibility of terrain and obstacles ahead of the aircraft and contribute to many of the accidents. This paper documents the results of twelve pilots in a simulation evaluating four types of visual conformal symbology sets in a low-visibility condition contour terrain flight: a scene-linked condition, a conformal line condition, a guidance line condition, and the combination of the two in a conformal + guidance condition. The results of combined quantitative and qualitative analyses strongly support the superiority of the contour lines over the scene-linked to ensure the safest flying behavior and the greatest situation awareness. However, the interindividual variability was very high, suggesting that a modular and selectable presentation of the different displays should be made available, as a function of the phase of the flight, the nature of the mission and the pilot's preferences.
Godfroy-Cooper, Martine, Szoboszlay, Zoltan, Kahana, Allon, Rottem-Hovev, Michal
Numerical Simulation of Multiple Interacting Wind Turbines on a Complex TerrainF-0072-2016-115825/17/2016
Modern wind farms are subjected to significant aerodynamic interference due to unsteady wakes of individual turbines as well as the complex terrains on which they are erected. The present study uses a new mixed basis formulation of the Navier-Stokes equations for accurate numerical simulation of convection-dominated flows on a complex terrain. The turbines are modeled using a distribution of momentum sources and the incompressible, turbulent flow-field is solved using the Reynolds Averaged Navier-Stokes (RANS) equations. A finite-volume procedure is used on body fitted grids and the SIMPLER algorithm is used to obtain the flow-field. Three different turbulence models including the standard, RNG, and realizable K - ε are implemented and compared. Results validating the ability of the numerical procedure to simulate flows over complex terrains and wind turbines are presented. Applications providing insights into the performance and loading on wind turbines subjected to turbine-terrain interference are studied. The evolution and interaction of the turbine wake with the complex terrain are also analyzed.
Murali, Avinaash, Rajagopalan, R.
Development of a Template Safety Case for Unmanned Aircraft Operations Over Populous Areas2015-01-24699/15/2015
One of the primary hazards associated with the operation of Unmanned Aircraft (UA) is the controlled or uncontrolled impact of the UA with terrain or objects on the terrain (e.g., people or structures). National Aviation Authorities (NAAs) have the responsibility of ensuring that the risks associated with this hazard are managed to an acceptable level. The NAA can mandate a range of technical (e.g., design standards) and operational (e.g., restrictions on flight) regulatory requirements. However, work to develop these regulations for UA is ongoing. Underpinning this rule-making process is a safety case showing how the regulatory requirements put in place ensure that the UA operation is acceptably safe for the given application and environment. There is no accepted framework for structuring or assessing the safety case for UA operations over populous areas, or for assessing the effectiveness of the wide range of potential technical and operational measures that can be potentially employed as part of a safety case. This paper presents a Barrier Bow Tie (BBT) model as a suitable template for the development and assessment of safety cases for UA operations over populous areas. The components of the BBT model and its application to UA operations over populous areas are presented. A case study is used to highlight the desirable features of the BBT model. The BBT model provides a systematic means for classifying and assessing proposed risk controls (the points of regulation) and how these controls contribute (in isolation and in combination) towards a reduction in risk.
Clothier, Reece, Williams, Brendan, Washington, Achim
COTS Rugged SystemsTBMG-223026/1/2015
North Atlantic Industries (NAI) recently received an initial contract from L-3 Maritime Systems for Custom-on-Standard Architecture™ (COSA™) COTS rugged systems for the Ship to Shore Connector (SSC) Data Acquisition Unit. The advanced, rugged intelligent I/O and communications subsystem delivers significant advantages for data acquisition and control solutions for the U.S. Navy’s new SSC program. The SSC is the successor to the Navy’s versatile Landing Craft Air Cushion (LCAC) vehicle, which is nearing its expected service life. Prime contractor for the detail design and construction of the Ship to Shore Connector, awarded under Naval Sea Systems Command (NAVSEA) Contract N00024-12-C-2401, is Textron Systems.
Analysis and optimization of All Terrain Wheelchair2015-01-13684/14/2015
An all-terrain wheelchair is a lever propelled wheelchair which enables an individual to drive on all terrains easily as the driving mechanism is efficient, ergonomic and fast. It also increases the reach capabilities and social boundaries of disabled. The paper is divided into two parts. In the first part, a comparative study of push rim wheelchair and All-terrain Wheelchair (lever propelled) has been done. In the second part, Optimization of this All-terrain Wheelchair has been done. The comparison is done on various parameters such as peak velocity, average velocity, acceleration, retardation, stroke frequency, reduction in effort, mechanical efficiency, obstacle climbing ability, turning radius, the distance travelled per stroke, Pressure cuts and burns caused during propelling the chair. Biomechanical testing is also done considering the heart rate and oxygen consumption level. This information was used to determine the energy demand, which is intrinsically connected to a wheelchair's mechanical efficiency. The optimization mainly focuses on ergonomics and efficiency of design. For this, the main emphasis was given on factors like the position of lever-drive system, configuration of wheel, seating, backrest, chassis, breaking and foot rest. this optimized design would make the chair more efficient and easy to use by enabling the person to drive, steer, and stop without even touching the wheels, thus, eliminating the risk of friction burns and protecting the wrists and shoulders from repetitive stresses. The analysis was done using commercial software ANSYS and CATIA and validation of results was conducted with the users and non-users of wheel chair.
Agarwal, Shikhar, Gautam, Saumya
Automatic Lunar Rock Detection and MappingTBMG-200227/1/2014
Safe spacecraft landing on planetary and small body surfaces is of primary concern. Estimation of landing risk is a critical task when evaluating and certifying potential landing sites. Such analyses require the detection and mapping of all potential landing hazards such as rocks and boulders, craters, slopes, and terrain roughness.
Enhanced Auditory Alert SystemsTBMG-200447/1/2014
Auditory warning systems for human interfaces are often designed around criteria that depend primarily upon signal loudness. It is well understood from the auditory literature that, by making an alert signal substantially louder than the measured background noise level, one can insure that an alert signal will be detectable. Such auditory alert systems have been used in the aviation industry for a number of years in order to raise the awareness of the crew for terrain proximity, for example. However, if an alert signal amplitude is too loud, the alert signal may produce a “startle effect” that hinders performance in some high-stress situations.
Aerospace & Defense Technology: May 201414AERP055/1/2014
Simulating lightweight vehicles operating on discrete terrain Researchers characterize the mobility of autonomous reconnaissance vehicles on terrain considered to be deformable, and represented as a collection of bodies of spherical shape.
Robust Semi-Active Ride Control under Stochastic Excitation2014-01-01454/1/2014
Ride control of military vehicles is challenging due to varied terrain and mission requirements such as operating weight. Achieving top speeds on rough terrain is typically considered a key performance parameter, which is always constrained by ride discomfort. Many military vehicles using passive suspensions suffer with compromised performance due to single tuning solution. To further stretch the performance domain to achieving higher speeds on rough roads, semi-active suspensions may offer a wide range of damping possibilities under varying conditions. In this paper, various semi-active control strategies are examined, and improvements have been made, particularly, to the acceleration-driven damper (ADD) strategy to make the approach more robust for varying operating conditions. A seven degrees of freedom ride model and a quarter-car model were developed that were excited by a random road process input modeled using an auto-regressive time series model. The proposed strategy shows promise as a cost-effective solution to improve the ride of a military vehicle over multiple stochastic terrains considering variation in operating weight.
Kolansky, Jeremy, Singh, Amandeep, Goryca, Jill
Investigating Vehicle Behavior on a Sloped Terrain Surface2014-01-08574/1/2014
Sloped medians provide a run-off area for errant vehicles so that they can be safely stopped off-road with or without barriers placed in the sloped median. However, in order to optimize the design of sloped medians and the containment barriers, it is essential to accurately model the behavior of vehicles on such sloped terrain surfaces. In this study, models of a vehicle fleet comprising a small sedan and a pickup truck and sloped terrain surface are developed in CarSim™ to simulate errant vehicle behavior on sloped median. Full-scale crash tests were conducted using the vehicle fleet driven across a 9.754 meters wide median with a 6:1 slope at speeds ranging from 30 to 70 km/h. Measured data such as the lateral accelerations of the vehicle as well as chassis rotations (roll and pitch) were synchronized with the vehicle motion obtained from the video data. The measured responses were compared with responses obtained from simulation in CarSim™ to validate the vehicle and slope terrain models. In addition, snapshots of recorded video footage from the tests were compared to CarSim™ video footage to show the fidelity of the simulation. The developed models will be used to carry out parametric studies to optimize the design of sloped medians and containment barriers.
Uzunsoy, Erdem, Bolarinwa, Emmanuel, Olatunbosun, Oluremi, He, Rui
Terrain Model as an Interface for Real-Time Vehicle Dynamics SimulationsTBMG-194264/1/2014
In order to enable off-road vehicle dynamics analysis simulations when traveling on soft soil, a deformable Vehicle Terrain Interface (VTI) model that interfaces with existing vehicle and tire dynamics models was developed. It is modularized to be interfaced to a multibody dynamics vehicle that supports the Standard Tire Interface (STI). Any tire model can be used that supports the STI as well; currently, both rigid and flexible tire models are supported.
Effect of Terrain Roughness on the Roll and Yaw Directional Stability of an Articulated Frame Steer Vehicle2013-01-23669/24/2013
Compared to the vehicles with conventional steering, the articulated frame steer vehicles (ASV) are known to exhibit lower directional and roll stability limits. Furthermore, the tire interactions with relatively rough terrains could adversely affect the directional and roll stability limits of an ASV due to terrain-induced variations in the vertical and lateral tire forces. It may thus be desirable to assess the dynamic safety of ASVs in terms of their directional control and stability limits while operating on different terrains. The effects of terrain roughness on the directional stability limits of an ASV are investigated through simulations of a comprehensive three-dimensional model of the vehicle with and without a rear axle suspension. The model incorporates a torsio-elastic rear axle suspension, a kineto-dynamic model of the frame steering struts and equivalent random profiles of different undeformable terrains together with coherence between the two tracks profiles. The simulations are performed to determine the stability limits of the ASV models while operating on different terrains, namely: a perfectly smooth surface, plowed field, pasture, gravel road, and the MVEE random course. The directional stability limits are defined in terms of the static and dynamic rollover thresholds, rearward amplification ratio, and critical speed corresponding to snaking instability under steady and transient steering inputs. The results suggest that the tire interactions with the rough terrains affect the stability limits of both the unsuspended and suspended vehicles in a highly adverse manner. The suspended vehicle responses, however, show less sensitivity to variations in the road roughness profile.
Pazooki, Alireza, Rakheja, Subhash, Cao, Dongpu
Power Consumption Analysis of a Flexible-Wheel Suspension Planetary Rover Operating upon Deformable Terrain2013-01-23849/24/2013
This study analyzes the power consumption of a specific Planetary Exploration Vehicle (PEV) subsystem known as Flexible-Wheel (FW) suspension, more specifically the interaction between a FW and the deformable terrain upon which it traverses. To achieve this a systematic and analytical calculation procedure has been developed, which culminates in the definition of three dimensionless properties to capture the FW-soil interaction. Aimed towards the design engineer participating in concept evaluation, and the control engineer conducting initial analyses, this study has found that the resistance coefficient for the interaction between a FW and the deformable terrain can, in general, be several orders of magnitude higher than the rolling resistance of a pneumatic tire operating upon rigid terrain. The sensitivity analyses also unveiled certain design parameters which have much more effect on the resistance coefficient than others, enabling the engineer to concentrate their efforts more effectively to achieve greater design optimization.
Jesson, Peter, Cao, Dongpu
Developing a Compact Continuous-State Markov Chain for Terrain Road Profiles2013-01-06294/8/2013
Accurate terrain models provide the chassis designer with a powerful tool to make informed design decisions early in the design process. It is beneficial to characterize the terrain as a stochastic process, allowing limitless amounts of synthetic terrain to be created from a small number of parameters. A continuous-state Markov chain is proposed as an alternative to the traditional discrete-state chain currently used in terrain modeling practice. For discrete-state chains, the profile transitions are quantized then characterized by a transition matrix (with many values). In contrast, the transition function of a continuous-state chain represents the probability density of transitioning between any two states in the continuum of terrain heights. The transition function developed in this work uses a location-scale distribution with polynomials modeling the parameters as functions of the current state. A maximum likelihood estimator is used to parameterize the coefficients of these polynomials. The logistic distribution is applied as a proof of concept, and other distributions are discussed as targets of future research.
Lambeth, Jacob N., Ferris, John, Reid, Alexander, Gorsich, David
Using Performance Margin and Dynamic Simulation for Location Aware Adaptation of Vehicle Dynamics2013-01-07034/8/2013
One seminal question that faces a vehicle's driver (either human or computer) is predicting the capability of the vehicle as it encounters upcoming terrain. A Performance Margin (PM) is defined in this work as the ratio of the required tractive effort to the available tractive effort for the front and rear respectively. This simple definition stems from and incorporates many traditional handling metrics and is robust in its scope of applicability. The PM is implemented in an Intervention Strategy demonstrating its use to avoid situations in which the vehicle exceeds its handling capabilities. Results from a design case study are presented to show the potential efficacy of developing a PM-based control system.
Matthews, Cullen C., Cho, Sukhwan, Ferris, John, Schlinkheider, Joerg, Montgomery, Matthew
Control Strategy for the Excitation of a Complete Vehicle Test Rig with Terrain Constraints2013-01-06714/8/2013
A unique concept for a multi-body test rig enabling the simulation of longitudinal, steering and vertical dynamics was developed at the Institute for Mechatronic Systems (IMS) at TU Darmstadt. A prototype of this IMS test rig is currently being built. In conjunction with the IMS test rig, the Vehicle Terrain Performance Laboratory (VTPL) at Virginia Tech further developed a full car, seven degree of freedom (7 DOF) simulation model capable of accurately reproducing measured displacement, pitch, and roll of the vehicle body due to terrain excitation. The results of the 7 DOF car model were used as the reference input to the multi-body IMS test rig model. The goal of the IMS/VTPL joint effort was to determine whether or not a controller for the IMS test rig vertical actuator could accurately reproduce wheel displacements due to different measured terrain constraints. This paper presents the prototype test rig, high-fidelity terrain measurement process, seven degree of freedom car model, and the vertical actuator control strategy. The results indicate that the vertical hydraulic actuator control meets the requirements needed to accurately reproduce excitations due to terrain constraints.
Fietzek, Rafael, Chin, Philip, Cheng, Cannon, LaBrie, Russell, Ferris, John, Rinderknecht, Stephan
Mobility and Energy Efficiency Analysis of a Terrain Truck2013-01-06724/8/2013
While much research has focused on improving terrain mobility, energy and fuel efficiency of terrain trucks, only a limited amount of investigation has gone into analysis of power distribution between the driving wheels. Distribution of power among the driving wheels has been shown to have a significant effect on vehicle operating characteristics for a given set of operating conditions and total power supplied to the wheels. Wheel power distribution is largely a function of the design of the driveline power dividing units (PDUs). In this paper, 6×6/6×4 terrain truck models are analyzed with the focus on various combinations of PDUs and suspension systems. While these models were found to have some common features, they demonstrate several different approaches to driveline system design. In order to further investigate the effect of wheel power split on mobility and energy/fuel efficiency in conjunction with suspension characteristics, this paper provides an analytical method and mathematical model for the entire truck, including driveline system (sets of PDUs), suspension, and tires under various typical operating conditions. Interactions between longitudinal and normal truck dynamics are first modeled and their influence on vehicle mobility and energy efficiency is analyzed. A computational algorithm is presented, which integrates equations for the driveline system with the suspension model (i.e., wheel normal reactions), along with a method for solving the integrated equations. Finally, an analysis of the effects of PDU combinations on truck mobility and energy efficiency is demonstrated.
Vantsevich, Vladimir V., Murphy, Dennis, Bortolin, Gianantonio
Regolith Advanced Surface Systems Operations Robot ExcavatorTBMG-154711/1/2013
The Regolith Advanced Surface Systems Operations Robot (RASSOR) excavator robot is a teleoperated mobility platform with a space regolith excavation capability. This more compact, lightweight design (
Wind-Driven Wireless Networked System of Mobile Sensors for Mars ExplorationTBMG-154741/1/2013
A revolutionary way is proposed of studying the surface of Mars using a wind-driven network of mobile sensors: GOWON. GOWON would be a scalable, self-powered and autonomous distributed system that could allow in situ mapping of a wide range of environmental phenomena in a much larger portion of the surface of Mars compared to earlier missions. It could improve the possibility of finding rare phenomena such as “blueberries” or bio-signatures and mapping their occurrence, through random wind-driven search. It would explore difficult terrains that were beyond the reach of previous missions, such as regions with very steep slopes and cluttered surfaces. GOWON has a potentially long life span, as individual elements can be added to the array periodically. It could potentially provide a costeffective solution for mapping wide areas of Martian terrain, enabling leaving a long-lasting sensing and searching infrastructure on the surface of Mars.
Using Multispectral Imaging for Ecological ObservationsTBMG-1536112/1/2012
With an airborne camera capable of making precise and detailed ecological observations, biologists at Applied Ecological Services (Brodhead, WI) are bringing satellite imagery closer to earth.
Image Sensors Enable Curiosity to Capture High-Definition Images From MarsTBMG-1535812/1/2012
The Mars Science Laboratory rover, Curiosity, is designed to assess whether Mars ever had an environment able to support life by deploying the most advanced set of scientific instruments ever sent to the planet. As part of that instrument suite, all four science cameras on the rover are designed using image sensors from Truesense Imaging to capture high-resolution color images of the planet.
A Distributive, Non-Destructive, Real-Time Approach to Snowpack MonitoringTBMG-1527012/1/2012
This invention is designed to ascertain the snow water equivalence (SWE) of snowpacks with better spatial and temporal resolutions than present techniques. The approach is ground-based, as opposed to some techniques that are air-based. In addition, the approach is compact, non-destructive, and can be communicated with remotely, and thus can be deployed in areas not possible with current methods.
Large Terrain Continuous Level of Detail 3D Visualization ToolTBMG-146809/1/2012
This software solved the problem of displaying terrains that are usually too large to be displayed on standard workstations in real time. The software can visualize terrain data sets composed of billions of vertices, and can display these data sets at greater than 30 frames per second.
Vision-Aided Autonomous Landing and Ingress of Micro Aerial VehiclesTBMG-146259/1/2012
Micro aerial vehicles have limited sensor suites and computational power. For reconnaissance tasks and to conserve energy, these systems need the ability to autonomously land at vantage points or enter buildings (ingress). But for autonomous navigation, information is needed to identify and guide the vehicle to the target. Vision algorithms can provide egomotion estimation and target detection using input from cameras that are easy to include in miniature systems.
Water Detection Based on Color VariationTBMG-138796/1/2012
This software has been designed to detect water bodies that are out in the open on cross-country terrain at close range (out to 30 meters), using imagery acquired from a stereo pair of color cameras mounted on a terrestrial, unmanned ground vehicle (UGV). This detector exploits the fact that the color variation across water bodies is generally larger and more uniform than that of other naturally occurring types of terrain, such as soil and vegetation. Non-traversable water bodies, such as large puddles, ponds, and lakes, are detected based on color variation, image intensity variance, image intensity gradient, size, and shape.
DspaceOgreTerrain 3D Terrain Visualization ToolTBMG-138776/1/2012
DspaceOgreTerrain is an extension to the DspaceOgre 3D visualization tool that supports real-time visualization of various terrain types, including digital elevation maps, planets, and meshes. DspaceOgreTerrain supports creating 3D representations of terrains and placing them in a scene graph. The 3D representations allow for a continuous level of detail, GPU-based rendering, and overlaying graphics like wheel tracks and shadows. It supports reading data from the SimScape terrain-modeling library.
Some Useful Additions to Calculate the Wall Heat Losses in Real Cycle Simulations2012-01-06734/16/2012
More than 20 years after the first presentation of the heat transfer equation according to Bargende [1,2], it is time to introduce some useful additions and enhancements, with respect to new and advanced combustion principles like diesel- and gasoline- homogeneous charge compression ignition (HCCI). In the existing heat transfer equation according to Bargende the calculation of the actual combustion chamber surface area is formulated in accordance with the work of Hohenberg. Hohenberg found experimentally that in the piston top land only about 20-30% of the wall heat flux values from the combustion chamber are transferred to the liner and piston wall. Hohenberg explained this phenomenon that is caused by lower gas temperature and convection level in charge within the piston top land volume. The formulation just adds the existing piston top land surface area multiplied by a specified factor to the surface of the combustion chamber. In this work, it is shown that an analytical calculation of this heat transfer problem is possible. Furthermore, it is also possible to analytically describe the influence of a possible leakage on this wall heat loss component, which results in a significant better description of the wall heat losses in the piston top land area with better results when simulating the wall temperature field of this area. The combustion-generated convection, which increases the heat transfer during combustion, was formulated empirically by squaring the heat-transfer-increasing effect, taking into account the different driving temperature gradients from the unburned and burned zones to the combustion chamber wall. This - in principle - analytical formulation has only proven to be sufficient for heat-releasing processes close to TDC. When the heat release is moved towards the expansion stroke, with the consequence of a reduced combustion related pressure increase, an underestimation of the combustion-generated convection can be observed. This underestimation occurs by principle in all heat transfer equations, in which the combustion-induced pressure change is used as a measure of the combustion-generated convection (e.g. Woschni and Hohenberg). This paper presents a new formulation for the combustion-generated convection that avoids this disadvantage and seems to be valid for all common combustion principles, including low temperature combustion without the existence of turbulent flame propagation. With these adaptations, the modified wall heat transfer equation correctly reflects the transient, spatially averaged wall heat losses for conventional, homogeneous operated SI-engines, stratified combustion in SI-engines, heterogeneous DI-diesel combustion, as well as diesel- and gasoline-HCCI combustion processes without any specific adjustments of empirical calibration factors. The accuracy of this enhanced heat transfer equation was carefully verified by evaluation of intensive in-cylinder pressure and fast-response surface temperature measurements.
Heinle, Moritz, Bargende, Michael, Berner, Hans-Juergen
3D Visualization for Phoenix Mars Lander Science OperationsTBMG-130363/1/2012
Planetary surface exploration missions present considerable operational challenges in the form of substantial communication delays, limited communication windows, and limited communication bandwidth. A 3D visualization software was developed and delivered to the 2008 Phoenix Mars Lander (PML) mission. The components of the system include an interactive 3D visualization environment called “Mercator,” terrain reconstruction software called the “Ames Stereo Pipeline,” and a server providing distributed access to terrain models. The software was successfully utilized during the mission for science analysis, site understanding, and science operations activity planning.
New Video Documents Three-Year Trek by Mars RoverTBMG-1221211/28/2011
A new video compiles 309 images taken by NASA’s Mars Exploration Rover Opportunity, providing an historic record of a three-year trek that totaled about 13 miles across a Martian plain pocked with smaller craters.
Surface Modeling to Support Small-Body Spacecraft Exploration and Proximity OperationsTBMG-1189211/1/2011
In order to simulate physically plausible surfaces that represent geologically evolved surfaces, demonstrating demanding surface-relative guidance navigation and control (GN&C) actions, such surfaces must be made to mimic the geological processes themselves. A report describes how, using software and algorithms to model body surfaces as a series of digital terrain maps, a series of processes was put in place that evolve the surface from some assumed nominal starting condition.
Terrain Truck: Control of Wheel Rotational Velocities and Tire Slippages2011-01-21579/13/2011
The dynamics of an AWD vehicle is determined by the interactions between the vehicle's wheels and the tire contact surface. Understanding and controlling these interactions drives the vehicle mobility and energy efficiency. In this paper new issues related to tire slippage control are addressed. The paper analytically demonstrates that two tires on the same axle with the same rotational speeds can have different slippages when the normal reaction and inflation pressure vary due to motion conditions. Hence, a new method is proposed to control the rotational velocity of the wheels in a way that provides the same slippages of the tires by accounting for changes in the normal load and tire inflation pressure. This approach is especially beneficial for vehicles with individual (electric) wheel drives which can be individually controlled by introducing the proposed algorithm for controlling both the vehicle linear velocity and the tire slippages. The developed method is based on continuously monitoring the normal load and tire inflation pressure and using them as the inputs to estimate the theoretical linear velocity of the wheel (zero slippage). The control algorithm, based on an inverse dynamics approach, adjusts the applied wheel torques via closed loop feedback control of both the measured angular velocity and slippage of the wheels. A vehicle model, based on empirical data of terrain and tires, is created in LabVIEW software to simulate the tires of a terrain truck to evaluate the control algorithm.
Wilson, Timothy, Siero, Matthew, Kopchick, Christopher, Vantsevich, Vladimir V.
Coastal On-line Assessment and Synthesis Tool 2.0TBMG-109379/1/2011
COAST (Coastal On-line Assessment and Synthesis Tool) is a 3D, open-source Earth data browser developed by leveraging and enhancing previous NASA open-source tools. These tools use satellite imagery and elevation data in a way that allows any user to zoom from orbit view down into any place on Earth, and enables the user to experience Earth terrain in a visually rich 3D view. The benefits associated with taking advantage of an open-source geo-browser are that it is free, extensible, and offers a worldwide developer community that is available to provide additional development and improvement potential.
INTEGRATED SURVEILLANCE SYSTEMARINC768-2 (Current)6/1/2011
This document defines an Integrated Surveillance System (ISS) capable of providing traffic, terrain and weather information to the flight deck crew. Supplement 2 provides enhancements in the traffic surveillance area to support ADS-B Out and ADS-B In functionality, ADS-Re-broadcast capability, and Traffic Information Services Broadcast (TIS-B).
Airlines Electronic Engineering Committee
Multi-Modal Image Registration and Matching for Localization of a Balloon on TitanTBMG-94523/1/2011
A solution was developed that matches visible/IR imagery aboard a balloon in Saturn’s moon Titan’s atmosphere to SAR (synthetic aperture radar) and visible/IR data acquired from orbit. A balloon in Titan’s atmosphere must be able to localize itself autonomously both globally and with respect to local terrain. The orbital data is used to provide the balloon imagery with global context.
Intake System Design Approach for Turbocharged MPFI SI Engine2011-26-00011/19/2011
The automotive industry is currently facing the challenge of significantly stringent requirements regarding CO₂ emission and fuel economy coming from both legislations and customer demand. Advanced engine technologies play a vital role for downsizing of gasoline engine. The development of key design technologies for high efficiency gasoline engines is required for the improvement of competitive power in the global automobile industry. This paper focused on effect of geometry of intake manifold of gas exchange process and consequently the performance of the engine. Specially, the optimal design technologies for the intake manifold and intake port shape must be established for high performance, increasingly stringent fuel economy and emission regulations. Space in vehicle or packaging constraints and cost are also important factors while consideration of the design. Two models of intake manifolds discussed in this paper, such as short runner intake manifold and long runner intake manifold with different plenum chambers. Parameters like manifold plenum volume, runner length affecting dynamically on gasoline turbocharged engine performance are studied and evaluated. By employing these parameters, performance prediction of 2.2-liter MPFI Turbocharged Gasoline Engine is done by using mathematical models made from AVL Boost 5.1 software. CFD simulations are conducted on the both proposal to examine the distribution of the air flow from plenum to individual runners. Actual test bed engine performance is predicted and compared with boost performance. Injector position is defined on last section of primary pipe or runner in order to maximize fuel vaporization. The fact, fuel should not be injected on port walls and accordingly angle has been confirmed by injector target test.
Jagtap, Harishchandra, Vinayak, Chavan, Koli, Ravindra
An Augmentation of G-Guidance AlgorithmsTBMG-90301/1/2011
The original G-Guidance algorithm provided an autonomous guidance and control policy for small-body proximity operations that took into account uncertainty and dynamics disturbances. However, there was a lack of robustness in regards to object proximity while in autonomous mode. The modified G-Guidance algorithm was augmented with a second operational mode that allows switching into a safety hover mode. This will cause a spacecraft to hover in place until a mission-planning algorithm can compute a safe new trajectory. No state or control constraints are violated. When a new, feasible state trajectory is calculated, the spacecraft will return to standard mode and maneuver toward the target. The main goal of this augmentation is to protect the spacecraft in the event that a landing surface or obstacle is closer or further than anticipated. The algorithm can be used for the mitigation of any unexpected trajectory or state changes that occur during standard mode operations.
On-road Turbulence: Part 22009-01-00024/20/2009
This work presents a second series of turbulence measurements made in a range of different on-road terrains and traffic conditions. Wind measurements were captured using a rake of four separate multi-hole pressure probes mounted to the front of a test vehicle traveling at a road speed of 100 km/h. Analysis of the data shows how the turbulence intensities and length scales are modified by terrain type, road side obstacles and the upstream wakes of other moving vehicles. A vertical ‘profile’ of turbulence near the ground is generated and spatial correlations between probes are examined. These on-road results are then compared to the turbulence levels generated by the Monash University wind tunnel. A new method and a series of targets are then proposed for improving the modeling of turbulence in automotive wind tunnels.
Wordley, Scott, Saunders, Jeff
Identifying Vehicle Model Parameters Using Measured Terrain Excitations2009-01-11974/20/2009
Currently, the final stages of chassis development are conducted on prototype vehicles, requiring vehicle manufacturers to dedicate copious resources to the development of each new vehicle platform. The objective of this work is to provide development engineers a system identification tool enabling them to use modeling and simulation to better estimate the required vehicle system parameters. This work develops a parameter identification method for existing vehicle models in which measured terrain data is used as the model excitation. The model was validated using a variety of excitation events and shown to provide accurate estimations of a vehicle’s roll, pitch, and vertical displacement.
Müller, Tobias, Ferris, John B., Detweiler, Zachary R., Smith, Hurtford
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