Research on contact model of track-soft sediment and traction performance of four-tracked seabed mining vehicle

In response to the global demand for commercial mining of deep-sea manganese nodules, the four-tracked mining vehicle (FTMV) with excellent tractive and travelling performance is crucial for constructing the entire commercial system. In order to better evaluate the tractive and travelling performance of the FTMV, the dynamic sinkage phenomenon concerning soft seabed and front-rear track effect are proposed. Meanwhile, the pressure-sinkage and traction force-slip rate mathematical models are established based on terramechanics theory. The quantitative calculation was carried out based on the model and found that the grouser's parameters affect the sinkage depth of the FTMV. In the range of 10 ~ 20 cm, the height of the rectangular grouser increases by 1 cm, which will lead to a 0.15 cm of sinkage depth decreased. When the ratio of rectangular grouser thickness to track shoe length is between 0.1 and 0.3, every 1% increase in this ratio will decrease a 0.13 cm of sinkage depth. The maximum traction force obtained by the FTMV from the soft seabed sediment was 54.5 kN, which occurred when the slip rate of the track was 16%. Moreover, due to the front-rear track effect, the traction force of the front and rear tracks showed a significant difference, the front track contributed 32.4 kN, and the rear track contributed 22.1 kN when the traction force reached the peak. Furthermore, the optimization directions for track parameters were suggested according to the relationship surface of the track dimensional parameters-slip-traction. It was found that each track was 4.2 ~ 6 m long, with a length-width ratio of 3.2, which was conducive to the reduction of track slip and got relatively much traction force from soft seabed sediment. The simulation results confirm dynamic sinkage and front-rear track effect and verify the accuracy of the new traction force-slip rate model, providing a valuable reference for the development of commercial deep-sea mining vehicles. •The dynamic sinkage phenomenon and the front-rear track effects of the four-tracked vehicle are proposed.•The track traction force-slip rate model of the four-tracked seabed mining vehicle was derived.•Quantitative calculations and three groups of computer simulations were conducted to verify the accuracy of the new traction force-slip rate model.