Shankar Krishnapillai

Military vehicles mostly operate on rough roads, and hence, stability and ride comfort is of paramount importance. This mine protected vehicle (MPV) is used by military for anti-insurgency operations in disturbed and unsafe areas which involves patrolling and recce 24 × 7 through uneven roads connecting villages. Hence, ride comfort to keep troops vibrant and fiery all the time and vehicle stability in the event of fire on move is utmost important. Ride analysis of three-axle MPV over rough terrain is not seen reported in literature, and hence, this study is an important contribution. This study focuses on analysing and modelling three-axle military vehicle suspension response using rough roads akin to military terrain generated as per the guidelines stated in ISO 8608 and minimizing vertical acceleration keeping in view the road holding parameter. The ride comfort is a measure of root mean square (r.m.s) acceleration at centre of gravity in vertical direction. Road holding is determined by the ability of a vehicle to stay in contact with road under all circumstances, especially while negotiating bump, braking, accelerating, and cornering. Power spectral densities of vertical displacement at reference spatial frequency are used to generate an artificial road profile of varying degree of roughness using MATLAB and serves as an input to Simulink model. The equations of motion are derived using Newton’s second law of motion for three-axle vehicle, and further passive suspension model is created using Simulink. The same is been validated using MATLAB code (ODE-45 solver) with same parameters. The response so obtained from passive model involves high vertical acceleration beyond permissible limits as mentioned in ISO 2631–1. Further obtaining optimum value of damping coefficient considering road holding and acceleration. The model is then incorporated with PID controller in an attempt to bring acceleration well within permissible limits of passenger comfort. Present model with parameters as derived provides better ride comfort and road holding with 14.30% reduction in r.m.s acceleration of sprung mass in vertical direction.