Understanding front-rear track effect of seabed mining vehicle and traction performance optimization

The dual-tracked deep-sea mining vehicles used for sea trials generally cannot meet the demands of large-scale manganese nodules production due to their inadequate load bearing and traction performance. Various seabed mining organizations have gradually started four-tracked mining vehicles as seabed traveling ore collection machines to meet the demand for enhanced tractive performance. A notable challenge encountered is the significant front-rear track effect observed when these vehicles navigate soft-cohesive sediments. Addressing this, our study introduces a novel design concept that involves setting the grouser heights with a deviation between the front and rear tracks, coupled with the development of a traction force-slip rate model inspired by this innovative approach. This model facilitates an in-depth analysis of the front-rear track effect, including phenomena such as deep sinkage and an increase in pitch angle experienced by vehicles on soft-cohesive terrains. It is calculated that the front and rear grouser deviation height of only 2 cm can improve the traction force by 21%. Utilizing the multi-body dynamics (MBD) method, we validated the effectiveness of this grouser height adjustment in mitigating front-rear track effects, demonstrating its potential to reduce sinkage by at least 30 mm and pitch angle by at least 0.3 degrees, thereby guiding the optimization strategy. Finally, through optimization simulation, we present optimized track structural parameter sets suitable for three types of seabed pavement, concluding that for soft silty soil, saturated high cohesive soil, and saturated soft sandy soil, the grouser deviation heights should be approximately 5.3, 4.1, and 2.0 cm, respectively. After applying the optimized track structural parameter sets, traction performance evaluation indexes, such as traction force and the traction force-disturbing area ratio, improved by at least 23.4% and 3.3%, respectively. Meanwhile, static sinkage was reduced by at least 21.4% across the three types of pavements.