Six-wheel drive (6WD) articulated dump truck has excellent passing ability and high productivity, but its stability should be improved. A dynamic model of 6WD articulated vehicle with 3 degree-of-freedom (DOF) is established. With the control variables of yaw velocity and side-slip angle at mass center of front body, a feedfoward-feedback control system is designed by linear quadratic regulator...

In this work we study steady-state cornering conditions for a single-track vehicle model without imposing restrictive (i.e., linearized) conditions on the tire slip. For each steadystate cornering condition we calculate the corresponding tire friction forces at the front and rear tires, as well as the required front steering angle and front and rear wheel slip ratios, to maintain constant veloc...

This paper addresses the problem of closing the loop from perception to action selection for unmanned ground vehicles, with a focus on navigating slopes. A new non-parametric learning technique is presented to generate a mobility representation where maximum feasible speed is used as a criterion to classify the world. The inputs to the algorithm are terrain gradients derived from an elevation m...

A common mobile robot design consists of three ‘omniwheels’ arranged at the vertices of an equilateral triangle, with wheel axles aligned with the rays from the center of the triangle to each wheel. Omniwheels, like standard wheels, are driven by the motors in a direction perpendicular to the wheel axle, but unlike standard wheels, can slip in a direction parallel to the axle. Unlike a steered ...

The Mecanum wheel was designed in Sweden in 1975. Using four of these wheels provides omni-directional movement for a vehicle without needing a conventional steering system (Muir & Neumann, 1990; Dickerson & Lapin, 1991; Braunl, 1999; Navy, USA, 2002 and Lunze & Schmid, 2002). The wheel itself consists of a hub carrying a number of free moving rollers angled at 45° about the hub's circumference...

Most fielded wheeled mobile robots (WMRs) today use basic 2D kinematic motion models in their planning, control, and estimation systems. On uneven or low traction terrain, or during aggressive maneuvers, higher fidelity models are required which account for suspension articulations, wheel slip, and liftoff. In this paper we present a simple, algorithmic method to construct 3D kinematic models f...

This paper proposes a method to predict maximum traction force for autonomous mobile robots on rough terrain in order to improve maneuverability. For predicting traction force, we utilize friction-slip curves based on modified Brixius model derived empirically in terramechanics, which is a function of mobility number Bn′ and slip ratio S. Friction-slip curves include physical characteristics of...

Graetz and Nusselt studied heat transfer between a developed laminar fluid flow and a tube at constant wall temperature. Here, we extend the Graetz–Nusselt problem to dense fluid flows with partial wall slip. Its limits correspond to the classical problems for no-slip and no-shear flow. The amount of heat transfer is expressed by the local Nusselt number Nux, which is defined as the ratio of co...

this paper deals with the threshold radius that warrants the use of single restraining rail for transit and railroads. different railways use different threshold radius from 91m to 365m to provide restraining rail. these threshold figures are probably experience driven choices. the need for restraining rail may be related to a so-called derailment alarm coefficient of 1.2 sustained over 2m leng...