A ¼ SCALE HYBRID FULL-TRACKED AIR-CUSHION VEHICLE FOR SWAMP PEAT TERRAIN IN MALAYSIA

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1 Proeedings of the International Conferene on Mehanial Engineering 7 (ICME7) 9-31 Deember 7, Dhaka, Bangladesh ICME7-FL- A ¼ SCALE HYBRID FULL-TRACKED AIR-CUSHION VEHICLE FOR SWAMP PEAT TERRAIN IN MALAYSIA A. Rahman 1, A.K.M Mohiuddin 1, A. Hossain, S. Nursyifa 1, A. Nora 1, N. Hidayah 1 and J. Eshah 1 1 Deartment of Mehanial Engineering, Kulliyyah of Engineering, International Islami University Malaysia, 31 Kuala Lumur, Malaysia. Deartment of Mehanial Engineering, Faulty of Engineering, University Industry Selangor, Malaysia. ABSTRACT This aer desribes design and develoment of a hybrid full rubber trak air-ushion vehile (HTACV) for olletion-transortation oeration of alm oil fresh fruit bunhes (FFB) on the low bearing aaity of 7 kn/m swam eat terrain. The full segmented rubber trak mehanism is used as the driving system to overome the rolling motion resistane and the air ushion system is used to inrease the floatation aaity of the vehile. The driving fore is rovided to eah of the trak system by an individual AC motor. The additional thrust (or,trative effort) is rovided to the vehile by using two roulsion systems for overoming the drag resistane of the air-ushion system. Mathematial models are inororated by aounting the kinematis and dynamis behavior of the vehile. The simulation of the trative erformane has been found as 6% tration oeffiient and 8% trative effiieny. Keywords: HTACV, Peat terrain, Bearing aaity, Trative erformane. 1. INTRODUCTION Colletion and transortation oeration of oil alm fresh fruit bunhes (FFB) on swam eat terrain in Malaysia artiularly in Sarwak and Sabah are greatly emhasized to design and develo the vehiles with high rossing ability, good trative erformane and maneuver on swam eat terrain. Many researh works have been arried out and different tyes of rototyes have been introdued Bekker (1969), Wong et al., (198), Wong (1), and Ataur et al., () for the olletion and transortation oerations of oil alm FFB in Malaysia on soft terrain inluding eat terrain. However, most of the vehiles were wheeled vehiles, traked vehiles and hybrid air-ushion vehiles inluding fully trak and fully tyre-wheeled air-ushion vehiles. It is found that the air-ushion system of all the existing vehiles are fixed in suh a way that it always slides with the movement of the vehile whih may result exessive ower onsumtion. Therefore, the air-ushion system should be fixed just few millimeters to of the ground that it ould be used when it is needed. In adding that sine the vehile is suorted by both traked system and air-ushion, the ontat area of the traked system and air-ushion must be determined roerly in order to otimize the ower utilization. A hybrid vehile whih ombines air-ushion tehnology with a driving mehanism has been roven to be an effiient solution for a heavy duty vehile on severe working onditions (Luo et. al., 3). This study roosed a hybrid fully segmented rubber traked air-ushion vehile whih would rovide the solution of olletion and transortation oeration of alm oil on low bearing. aaity (7 kn/m ) swam eat terrain.. DESCRIPTION OF PROPOSED VEHICLE The roosed vehile will be omrised mainly with full trak system, skirt air-ushion and air-ushion roulsion system, AC motors, two roellers, a battery ak, and a small engine are shown in figure 1. The full segmented rubber trak mehanism will be used as driving system to overome traveling resistane, and the flexible skirt air-ushion as vehile body to suort vehile artial weight. The driving fore will be rovided to eah of the trak system by an individual AC motor. The skirt air-ushion system will be mounted with the inner sides of the traked system and just mm from the bottom of the traked system. The additional thrust will be rovided to the air-ushion system by two small roellers. The vehile ould run on the unreared swam eat terrain at least 1 km from a single harging battery. After traveling the vehile 9km the battery will be reharged by the engine automatially. The automati reharging system of the battery will be inororated by introduing a Hall Effet Sensor. The air-ushion system will be used to make the vehile ground ontat ressure even less than kn/m. The hovering ressure to the air-ushion will be rovided by a single omressor to suort the artial vehile weight. ICME7 1 FL-

2 L F = B τ dx (1) The τ is the shear stress of the terrain in kn/m whih an be found by using the following equation rovided by Wong (1). Fig 1: D Strutural view of the vehile The omressor will start automatially when any of the traks sink mm. The starting system of the omressor will be inororated by using an indutive sensor. The AC motors, the omressor, and the roeller will reeive ower from a rehargeable high am-hr battery. Small IC engine will be used to reharge the battery if the vehile oerate more that 9 km. Figure shows the trak system of the vehile. τ = τ max j K x w j ex 1 K τ ( σ tanϕ) Where, max = + x w and j x = ix Notifiations: S1= Setion 1, S=Setion, S3=Setion 3, S4=Setion Fig : Trak system 3. MATHEMATICAL MODEL Basially, there are two tyes of mathematial modeling one of them onsiders the uniform ground ressure distribution and another one involved non-uniform ground ressure distribution. This sudy resents the mathematial modelling for the uniform ground ressure distribution (UGPD) shown in Figure 3. A traked vehile develos its trative effort by deforming the soil in longitudinal shear. As the vehile moves aross the soil, a ounter fore arises from the soil and is equal to the trative effort. In other sense, it an be defined as the fore of the vehile that an be generated at the terrain interfae. The trative effort is develoed not only at the ground ontat art of the trak but also at the trak sides. However, for this rojet we are onsidering only the trative effort develoed at the bottom art of the trak. To add, the trative effort of the vehile in this study is going to be alulated in two ways. (i) For sinkage, z m The trative effort of the vehile an be reresented as the shearing stress effet of the vehile trak system. Therefore, the trative system of the vehile an be reresented as follows: Fig 3: Flow hart for the model of vehile straight motion with UGPD By integrating the Eq. (1), the trative effort equation for the bottom of the vehile s trak ground ontat art on eat terrain was derived by the Ataur et.al (): K = ( + + w 1 K ) + w il F b At ( W W ) tan ϕ e 1 ex 1 il il K w () where, F b is trative effort that develo at the bottom art of the trak in kn and L is the ground ontat art of the trak in m, A t is the area of the trak ground ontat length in m, σ is the vehile normal stress kn/m, W is the total load of the vehile in kn, W is the air ushion load, is the ohesiveness in kn/m, ϕ is the terrain internal frition angle in degree, K w shear deformation modulus in m, i is the sliage of the vehile in erentage. ICME7 FL-

3 (ii) For sinkage, z m The trative effort of the vehile is alulated by using the equation of Luo et al. (3) as ited in Ataur et. al () : K w K w il F t = ( At + W tan 1 ϕ ) e 1 + ex + Csk P A il il 1 K w (3) where, F t is the trative effort of the vehile after the air-ushion touhes the terrain in kn, P is the air ressure in ushion in kn/m, and A is the ushion effetive area in m Motion Resistane The motion resistanes from aerodynamis and trak belly drag omonent in the omutations of the total motion resistane are not signifiant. Hene, the total motion resistane due to trak omation will affet the vehile differently for different values of sinkage. (i) For sinkage, z m R = R + R (ii) For sinkage, z m R = R + R + R t t in in where, R is the motion resistane of the vehile due to terrain omation in kn, R in is the vehile rolling omonents internal fritional resistane, and R sk is the skirt-ground interation resistane in kn. The motion resistane of the vehile due to terrain omation an be reresented by the simlified equation of Wong, J. Y. (1) given first in general formulation: R L = z sk (4) () BL dz (6) where, is the ground ontat ressure. It an be alulated by using the equation rovided by Wong, J. Y. (1): 4 = ( k z + m m z ) D By integrating the Eq. (6), the motion resistane equation was derived by Wong, J. Y. (1) : = k z 4 3 R B + m 3D z (7) m h where, R is the vehile motion resistane due to soil omation in kn. (i) For sinkage, z m R = k z1 4 B + m 3D z m h (ii) For sinkage, z m h 3 1 k z R B 4 3 = + mm z + C D 3 h sk P A 3. STUDIES ON DESIGN PARAMETERS Vehile design arameters has been studied by onsidering the Sarwak eat terrain s lowest bearing aaity and the lowest sinkage and the lowest value of mehanial arameters as shown in Table 1. Table 1: Terrain arameters (Ataur et al. (4)) Un-drained Parameters Seang Sarwak Mean value Mean value ω, (%) γ, (g/m 3 ).8.4, kn/m ) ϕ, (degree) 1.64 K w, (m) m m,(kn/m 3 ) k, (kn/m 3 ) There are three tyes of loaded vehile suh as 3.9 kn,.88kn and 7.8 kn and the vehile traveling seed 1 km/h are onsidered for the study of the vehile design arameters. Figure 4 shows one of a moderate ondition eat terrain in Malaysia. From the observation, the water table was found very high and the terrain surfae mat thikness was found in the range of - m and -1 m. The bearing aaity of the Sarwak eat terrain 7kN/m² and surfae mat thikness m are onsidered. The simulation on the vehile arameters are onduted by using the MATLAB, RECRDYNE and Mirosoft Exel. (a) before drainage (b) after drainage Fig 4: Photograh of the moderate eat terrain Figure shows the vehile sinkage for three different loading onditions. In this study the trak ground ontat length is ket onstant at 1. m and traked width.4 m whih is available in the market as needed. Therefore, the vehile trak ground ontat area is always onsidered as.8 m. From the Figure, it is observed that the vehile sinkage is found more than. m for all of the vehile s loading onditions. As the terrain ICME7 3 FL-

4 mehanial arameters suh as k,and m m,and trak size L and B are onstants, so it is imortant to inrease the vehile ground ontat area in order to get the vehile sinkage m and ground ontat ressure 7 kn/m. The ground ontat ressure of the vehile with air ushion system is less omared to an idential vehile without an air ushion. This is due to the fat that when the air ushion is taken into onsideration, the orresonding hydrauli diameter is inreased. Moreover, the air ushion is used to suort artial load of the vehile, ausing the ground ontat ressure to derease as the sinkage is inreased. Furthermore, the air ushion inreases the ground ontat area of the vehile and results derease the ground ontat ressure and inrease mobility of the vehile over the unreared eat terrain. Ground ontat area only for the vehile s trak is onsidered.8 m. With this trak ground ontat area, the vehile will able to traverse on the Sarwak eat terrain with any loading ondition as the sinkage is higher than m. It an be noted that motion resistane due to omation inreases as the trak width inreases from.17 m to.381 m by onsidering k, m m, L and W are onstants, having the values of kn/m 3, 14.4 kn/m 3, 1m and.886kn resetively. But, if the vehile equied with air-ushion system of ground ontat area.44 m, the vehile will able to traverse on the Sarwak swam eat terrain with all of the loading onditions. In order to evaluate the erformane of the vehile on the eat-terrain, the behavior of the ground ontat ressure with reset to sinkage is illustrated in Figure 6. In the early of this study, it is mentioned that the ritial ground ontat ressure of the vehile on Sarwak eat terrain is 7kN/m. Figure 6 (a) shows that the vehile ould be allow to traverse on the Sarwak swam eat terrain with all three loading onditions only if the vehile is equied with ground ontat area 1 m or more (i.e, 1. At ) but the trak ground ontat area is only onsidered.8 m. Figure (b) shows that if the vehile whih trak ground ontat area of.8 m is equied with.44 m air-ushion, vehile would traverse on the swam eat terrain easily. Figure 7 shows the relationshi between the vehile trative effort and motion resistane. Figure 7 (a) shows that if the vehile terrain omation motions within the shaded area or the trative effort the vehile is only able to traverse on the eat terrain. Moreover, the vehile total ontat area is used 1. m inluding.44 m of air-ushion area. The vehile has needed to develo additional. kn trative effort in order to traverse on the eat terrain with overoming only the omation motion resistane. Again, Figure 7 (b) shows that for the vehile ground ontat area of 1. m inluding.44 m of air-ushion area vehile has needed to develo additional.7 kn. Therefore, this study reresented roeller system, whih will able to develo 1.kN trative effort to traverse the vehile on swam eat terrain. Sinkage, m Sinkage, m Vehile gorund ontat area, m kn vehile.88 kn vehile 3.9 kn vehile Critial sinkage (a) Vehile ground ontat area, m 3.9 kn vehile.88 kn vehile 7.8 kn vehile Critial sinkage (b) Fig : Vehile sinkage (a) without trak system, (b) with trak system. Pressure, kn/m Pressure, kn/m Vehile ground ontat area,m 7.8kN vehile.88 kn vehile 3.9 kn vehile Critial ressure (a) Vehile ground ontat area, m 3.9 kn vehile.88 kn vehile 7.8 kn vehile Critial ressure (b) Fig 6: Vehile ground ontat ressure (a) without air-ushion (b) with air-ushion ICME7 4 FL-

5 Fore, kn Fore, kn 3 Trative effort Comation Motion resistane 1 Vehile ground ontat area,m (a) Comation motion resistane 3 Trative effort Total motion resistans 1 Vehile ontat area, m (b) Total motion resistane Fig 7: Trative effort and motion resistane Load distribution ratio Trak ground ontat area, m 7.8 kn vehile.88 kn vehile 3.9 kn vehile Fig8: Load distribution Pow er onsumtion, kw Load distribution, kn vehile ground ontat area, m Fig 9: Power onsumtion Figure 8 shows the load distribution (define as the load transferred from the traveling system to air-ushion system in order to limit the vehile sinkage and to maintain the vehile ground ontat ressure distribution). The load distribution to the air-ushion system is dereased linearly with inreasing the trak ground ontat area. It is noted that the required driving fore inreases with dereasing the load distribution. Figure 9 shows the load distribution to the air-ushion signifiantly affet the total ower onsumtion of the vehile. 4. CONCLUSIONS A new design method with roeller is roosed for a ¼ sale hybrid full rubber trak air ushion vehile (HTACV) for olletion-transortation oeration of alm oil fresh fruit bunhes (FFB) on the low bearing aaity of 7 kn/m swam eat terrain and a rototye of the vehile is develoed. The driving fore is rovided to eah of the trak system by an individual AC motor and two roulsion systems are used for overoming the drag resistane of the air-ushion system. (i) Based on the simulation results, the following onlusions ould be made: Vehile ground ressure ould be made 7 kn/m by adding.44 m air-ushion with trak ground ontat area of.8 m. Trative erformane has been found as 6% tration oeffiient and 8% trative effiieny. Otimal load distribution ratio results in minimum total ower onsumtion. (ii) The vehile ould be made suitable for oerating on the swam eat terrain with otimizing the suorting systems as.44 m air-ushion and trak ground ontat area of.8 m.. ACKNOWLEDGEMENT The authors are grateful for the suort rovided by finanial assistane and Faulty of Engineering of the International Islami University Malaysia (IIUM) for the overall failities. 6. REFERENCES 1. Bekker, M.G., 1969, Introdution to terrain-vehile systems, Ann Arbor, MI: University of Mihigan Press.. Wong, J. Y., Radforth, R., and Preston-Thomas, J., 198, Some further studies on the mehanial roerties of muskeg in relation to vehile mobility, Journal of Terramehanis, 19 (), Wong, J. Y., 1, Theory of Ground Vehile, (Third Edition), New York: John Willey & Sons, In. 4. Ataur, R., Azmi, Y., Zohadie, M., Ahmad, D and Ishak, W.,, Design and Develoment of a Segmented Rubber Traked Vehile for Seang Peat Terrain in Malaysia, Int. J. of Heavy Vehile Systems, Vol.1 No.3, Luo, Z., Yu, F., and Chen, B.C., 3, Design of a novel semi-traked air-ushion vehile for soft terrain, Int. J. of Vehile Design, Vol. 31. No. 1, ICME7 FL-

6 6. Ataur, R., Azmi, Y., Zohaide, B., Ahmad, D., and Wan, I., 4, Mehanial roerties in relation to mobility of Seang eat terrain in Malaysia, Journal of Terramehanis, Vol.41, No.1, NOMENCLATURE Symbo Meaning Unit l z Sinkage (m) F Trative effort (kn) τ Shear stress (kn/m ) F b Trative effort at the bottom (kn) L Trak ground ontat length (m) A t Trak ground ontat area (m ) σ Vehile normal stress (kn/m ) W Total load of the vehile (kn) W Air ushion load (kn) Cohesiveness (kn/m ) ϕ Terrain internal frition degree angle K w Shear deformation modulus (m) i Sliage of the vehile (%) F t Trative effort of vehile (kn) after the air-ushion touhes terrain P Air ressure in ushion (kn/m ) A Cushion effetive area (m ) R Motion resistane of vehile (kn) due to terrain omation R in vehile rolling omonents (kn) internal fritional resistane R sk Skirt-ground interation (kn) resistane D h Hydrauli diameter (m) P Ground ontat ressure (kn/m ) ICME7 6 FL-