Study on Steerability of Tracked Vehicles on Soft Ground (Part 2)

Ground Deformation and Turning Radius

Abstract

In the previous paper, we presented a theoretical analysis of steerability of tracked vehicles during stationary turns at low speed on a flat soft ground.
In this paper, the ground deformation and turning radius of the tracked vehicle was analyzed experimentally and compared with the results of the theoretical analysis. The turning tests were carried out on a flat dry loose standard sand bin using the scale model.
The main results were as follows;
1. The experimental results were well correlated with the theoretical values.
2. The track slippage can be expressed by the slip radius of track A_j. The slip radius of the inner track A₁ was positive and approximately constant, independent of the steering ratio, but the slip radius of the outer track A₂ was negative and varied with the steering ratio.
3. The turning radius was approximately 1.4-1.5 times larger than the calculated value based on a simple geometrical relation which neglects the effects of longitudinal tracks slippage.
4. During the turning motion, the sinkage of tracks on the ground differed each other. The depth of rut of the inner track increased propotionally to the steering ratio, while the depth of rut of the outer track increased by slow degrees with the steering ratio.
5. In the inner track, the quantity of sinkage under the final road wheel Δz_1n was deeper than the quantity of sinkage under the other road wheels Δz_1i, while in the outer track, the quantity of sinkage under the first road wheel Δz_2l was deeper than Δz_2i.