Increasing maneuverability of caterpillar tractors with differential steering mechanisms by activating stopping brakes of lagging sides with an abrupt change in the trajectory curvature

Abstract

The paper presents a study of curvilinear motion of 10-ton industrial caterpillar tractors with differential steering mechanisms. Hard ground conditions and abrupt maneuvering lead to overpressure of hydrostatic drives, which form the basis of differential steering mechanisms. We proposed and verified an algorithm for steering control by the joint action of the hydrostatic drive and the stopping brake of the lagging side. In this case, the stopping brake is activated by the method of pulse-width modulation under certain conditions determined by mathematical simulation. It was shown that activation of the stopping brake under overloading of the hydrostatic drive is not effective. The same is characteristic of the stopping brake of the lagging side during the transition of trajectory change. We modeled tractor motion along a steady curved trajectory when the stopping brake of the lagging side activates. It was found that the tractor does not stop, despite the conflicting efforts of the stopping brake and hydrostatic drive under these conditions.
The problem is that a hydrostatic drive is not an absolutely rigid link in a power circuit and, counteracting to the stopping brake, it either dumps the working fluid through a safety valve or transitions to a generating mode.