Body roll control of a lightweight military ground vehicle under recoil impulse using gyrostabilizers

Abstract

Future ground combat vehicles are anticipated to be unmanned, in contrast to the heavily armoured vehicles of today. By eliminating the crew, the need for thick protective armour is also eliminated. This reduction in armour results in lighter vehicles, enhancing mobility and logistics capabilities. Despite being lighter and smaller, an effective armament is still a requirement. One suitable choice is a 40 mm chain gun with a stabilized turret, offering armour penetration capability and versatility with various types of ammunition. However, firing a large-calibre gun from a lightweight platform poses challenges to vehicle stability and gun aiming. This study proposes a body roll control technique for a lightweight ground combat vehicle, specifically addressing the stability concerns caused by the firing impulse of a large calibre gun. Traditionally, recoil problems are handled on the gun side, but this technique focuses on solving the issue on the platform side. The novel approach involves measuring the vehicle's body roll and applying a counter moment using gyrostabilizers, a first-time application for this purpose. The worst-case scenario of broadside firing is considered. The platform is modelled as a half-car engaged with a damped harmonic oscillator representing the recoiling gun. Three degrees of freedom are considered in the model, and disturbance forces from the gun and road are incorporated. To generate a counter moment, twin constant spin, single gimbal gyrostabilizers are employed. The moment produced by the gyrostabilizers are adjusted by precisely controlling their precession rates. Overall system exhibits nonlinear characteristics, with mismatched disturbance. Initially, PID control approach is applied. Results came out to be mediocre due to the impulsive characteristics of disturbance force and nonlinear characteristic of the system. Later, to enhance the performance of PID, Fuzzy Logic Controller (FLC) are implemented to adaptively change the gains of the PID controller. The Fuzzy Tuned PID controller showed overall better performance. Subsequently, a sliding mode control (SMC) scheme is utilized, but to address the chattering issue, different switching functions proposed in literature are adopted. The Super Twisting switching function (STSMC) with the boundary layer approach are resulted best among all. All control schemes are compared in terms of error, power consumption and other feasibility constraints. Not only the gun disturbance but also the road disturbance ability of the proposed technique is demonstrated is simulation environment. Finally, a test setup is established to further test the concept and compare control schemes. The actual size simulation model is scaled down for practical reasons, and PID and SMC controllers are embedded into the hardware. Test results confirm the compensation of body roll due to firing impulse, with the STSMC performing better, consistent with the simulation results. In conclusion, the study demonstrates successful control of body roll in a vehicle with small rotational inertia, compensating for disturbances caused by gun firing and rough terrain. The outcomes contribute to the safety, stability, and aiming performance of future ground combat vehicles.