Publication news

Journal of Terramechanics, Vol. 49, Issue 2

B. Janarthanan, Chandramouli Padmanabhan, C. Sujatha
Longitudinal dynamics of a tracked vehicle: Simulation and experiment
Journal of Terramechanics, Volume 49, Issue 2, April 2012, Pages 63-72, ISSN 0022-4898, 10.1016/j.jterra.2011.11.001.
Abstract: In recent years virtual dynamic system simulation has become very important in the design and development stage, as new strategies can be examined without expensive measurements and with reduced time. This paper describes the development of a simulation model for transient analysis of the longitudinal dynamics of a heavy tracked vehicle. The driving inputs for this simulation model are obtained from a powertrain model. The main elements of the powertrain include the engine, Torque Converter (TC), transmission and drivetrain. Here the engine is modeled based on the engine maps from steady-state experiments. The TC is modeled based on its characteristic map from experiments. A fairly simple transmission model is used which is based on static gear ratios assuming small shift times. The final drivetrain model however includes the rotational dynamics of the sprocket. The simulation model developed is validated by comparing the predicted values with the measured data from experiments. The results have demonstrated that the developed model is able to predict fairly accurately the acceleration and braking performance of the heavy tracked vehicle on both soft and hard terrain.
Keywords: Engine; Torque converter; Transmission; Drivetrain; Powertrain; Tracked vehicle

Altab Hossain, Ataur Rahman, A.K.M. Mohiuddin
Fuzzy evaluation for an intelligent air-cushion tracked vehicle performance investigation

Journal of Terramechanics, Volume 49, Issue 2, April 2012, Pages 73-80, ISSN 0022-4898, 10.1016/j.jterra.2011.08.002.
Abstract: This paper presents the fuzzy logic expert system (FLES) for an intelligent air-cushion tracked vehicle performance investigation operating on swamp peat terrain. Compared with traditional logic model, fuzzy logic is more efficient in linking the multiple units to a single output and is invaluable supplements to classical hard computing techniques. Therefore, the main purpose of this study is to investigate the relationship between vehicle working parameters and performance characteristics, and to evaluate how fuzzy logic expert system plays an important role in prediction of vehicle performance. Experimental values are taken in the swamp peat terrain for vehicle performance investigation. In this paper, a fuzzy logic expert system model, based on Mamdani approach, is developed to predict the tractive efficiency and power consumption. Verification of the developed fuzzy logic model is carried out through various numerical error criteria. For all parameters, the relative error of predicted values are found to be less than the acceptable limits (10%) and goodness of fit of the predicted values are found to be close to 1.0 as expected and hence shows the good performance of the developed system.
Keywords: Vehicle performance; Fuzzy logic; Relative error; Goodness of fit

E. Alex Baylot, George L. Mason, John G. Green, Ernest S. Berney IV
Predicting the stability of low volume road embankments in contingency areas

Journal of Terramechanics, Volume 49, Issue 2, April 2012, Pages 95-101, ISSN 0022-4898, 10.1016/j.jterra.2012.01.002.
Abstract: The US Army often operates heavy vehicles in rural areas, operating on low-volume roads having limited load carrying capacity. Many of these roads, such as the ones on the outskirts of Baghdad, have been raised to prevent flooding from nearby canals or irrigated fields. Sections of the roads have collapsed under the weight of armored vehicles, resulting in injuries and even fatalities. For the selected area studied, 2½% of the low-volume road sections were determined to be high risk given typical wheel loads of heavy vehicles for soil strength conditions modeled as low. The goal of the research was to develop a method for rapidly evaluating the stability of a road based on soil conditions, wheel load, and the dimensions of a vehicle. A model for road stability was developed to assist in performing analysis of the canal roads outside of Baghdad. This analysis was then used to create maps and charts characterizing road stability to assist the drivers. The procedure described in this paper can be used to evaluate elevated roads in other parts of the world.
Keywords: Low volume road; Embankment; Traffic; Heavy vehicles; Trafficability; Soil strength; Stability

T. Heyns, P.S. Heyns, J.P. de Villiers
A method for real-time condition monitoring of haul roads based on Bayesian parameter estimation
Journal of Terramechanics, Volume 49, Issue 2, April 2012, Pages 103-113, ISSN 0022-4898, 10.1016/j.jterra.2011.12.001.
Abstract: Current haul road management techniques, such as routine, periodic and urgent maintenance have shortcomings in many complex haul road environments. Real-time road condition monitoring may significantly reduce maintenance costs, both to the road and to the vehicles. A recent idea is that vehicle on-board data collection systems could be used to monitor haul roads on a real-time basis by means of vibration signature analysis. This paper proposes a methodology based on Bayesian regression to isolate the effect of varying vehicle speed on the measured vehicle response metric. A key feature of the proposed methodology is that it avoids the costly need to generate analytical or empirical vehicle models.
Keywords: Monitoring of road condition; Bayesian parameter estimation; Condition based maintenance

S. Chhaniyara, C. Brunskill, B. Yeomans, M.C. Matthews, C. Saaj, S. Ransom, L. Richter
Terrain trafficability analysis and soil mechanical property identification for planetary rovers: A survey
Journal of Terramechanics, Volume 49, Issue 2, April 2012, Pages 115-128, ISSN 0022-4898, 10.1016/j.jterra.2012.01.001.
Abstract: The advances in the field of robotics enabled successful exploration of the Moon and Mars. Over the years, rover missions have demonstrated deployment of various scientific payloads for robotic field geology on these extra-terrestrial bodies. The success of these missions clearly emphasises the need to further advance rover technology in order to maximise scientific return. The success of future robotic surface exploration missions will depend on two key factors – autonomy and mobility on soft sandy and unstructured terrains. The main contribution of this paper is that it brings together vital information pertaining to various terrain characterisation techniques into a single article. Special care is taken in structuring the paper so that all the relevant terrain characterisation methods that have been used in past planetary exploration missions and those under consideration for future space exploration missions are covered. This paper will not only lists advantages and disadvantages of various terrain characterisation techniques but also presents the methodology for evaluating and comparing terrain characterisation techniques and provides a trade-off study of existing and potential approaches that could improve the mobility of future planetary exploration rovers. This survey shows that further advances in currently deployed technology are required in order to develop intelligent, on-board sensing systems which will detect and identify near surface and sub-surface terrain properties to enhance the mobility of rovers.
Keywords: Trafficability; Mobility; Planetary exploration; Autonomy; Mobile robotic platforms; Terrain characterisation; Sensors