A simulation study was conducted to evaluate three terramechanics methods used for predicting single wheel performance of small vehicles on granular terrain. Traditional Bekker-type terramechanics methods do not consider the soil profile, the soil dynamics, or the transient wheel dynamics, which can be important factors in vehicle performance. The ‘dynamic Bekker’ method used to overcome these ...

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 ...

A numerical study was conducted using the discrete element method (DEM) to investigate the performance and mobility impacts of rough terrain operation for small unmanned ground vehicles. The DEM simulation was validated using experimental data from two types of single-wheel tests previously published in the literature: straight-line locomotion over flat, level soil, and wheel-digging. Results f...

The fractal tree-like branched network is an effective channel design structure to reduce the hydraulic resistance as compared with the conventional parallel channel network. In order for a laminar flow to achieve minimum hydraulic resistance, it is believed that the optimal fractal tree-like channel network obeys the well-accepted Murray's law of βm = N-1/3 (βm is the optimal diameter ratio be...

Vehicle Dynamics Control (VDC) systems require the information about system variables, which cannot be directly measured, e.g., the wheel slip or the vehicle side-slip angle. This paper presents a new concept for the vehicle state estimation under assumption that the vehicle is equipped with the standard VDC sensors. It is proposed to utilize an Unscented Kalman Filter (UKF) for estimation purp...

The in-wheel electric vehicle is expected to be a popular next-generation vehicle because an in-wheel system can simplify the powertrain and improve driving performance. In addition, it also has an advantage in that it maximizes driving efficiency through independent torque control considering the motor efficiency. However, there is an instability problem if only the driving torque is controlle...

This paper proposes an innovative way to interface the concept of FUZZY LOGIC and ABS system used (mainly in transportation and motors) and tests on an experimental car with antilock-braking system (ABS) and vehicle speed estimation using fuzzy logic. Vehicle dynamics and braking systems are complex and behave strongly non-linear which causes difficulties in developing a classical controller fo...

We describe a nonlinear observer-based design for control of vehicle traction that is important in providing safety and obtaining desired longitudinal vehicle motion. First, a robust sliding mode controller is designed to maintain the wheel slip at any given value. Simulations show that longitudinal traction controller is capable of controlling the vehicle with parameter deviations and disturba...

The next round of planetary missions will require increased autonomy to enable exploration rovers to travel great distances with limited aid from a human operator. For autonomous operations at this scale, localization and terrain modeling become key aspects of onboard rover functionality. Previous Mars rover missions have relied on odometric sensors such as wheel encoders and inertial measureme...

Wheeled mobile robots (WMRs) have a numerous applications and planetary of exploration tasks, all of which require building the suitable dynamic model of the robot. Also, the optimal control model that is intended to guide the robot to accomplish its mission is of a significant need. In addition, it is a certain that achieving a success in the robot controller mission requires an accurate estim...