In-wheel-motor-drive electric vehicles have attracted enormous attention due to its potentials of improving vehicle performance and safety. Road surface roughness results in forced vibration in-wheel-motor (IWM) thus aggravates the unbalanced magnetic force (UEMF) between rotor stator. This can further compromise vertical longitudinal dynamics. paper presents a comprehensive study reveal couple...

Nonlinear hunting speeds of railway vehicles running on a tangent track are analytically obtained using Hopf bifurcation theory in this paper. The railway vehicle model consists of nonlinear primary yaw dampers, nonlinear flange contact stiffness as well as the clearance between the wheel flange and rail tread. Linear and nonlinear critical speeds are obtained using Bogoliubov method. A compreh...

Wheel out-of-roundness (OOR) inevitably jeopardizes the safety of railway operations. Regular visual inspection and checking by experienced workers are the commonly adopted practices to identify wheel defects. However, the defects may not be spotted in time. The paper puts forward a new method to real-time monitor wheel OOR based on PVDF strain sensor. Track strain response upon wheel-rail inte...

A riderless bicycle can automatically steer itself so as to recover from falls. The common view is that this self-steering is caused by gyroscopic precession of the front wheel, or by the wheel contact trailing like a caster behind the steer axis. We show that neither effect is necessary for self-stability. Using linearized stability calculations as a guide, we built a bicycle with extra counte...

This paper deals with the simulation of oo-road robots while taking into account the mechanical behavior of the locomotion system and its interaction with its environment. This interaction is studied and discussed for diierent behaviors of wheel-soil contact. The analysis considers phenomena of slips, of soil shear deformations, of soil compaction and wheel elastic deformation. Wheel-soil conta...

Descriptor systems with inequality (unilateral) constraints may have singularities (impasse points) if the set of active constraints changes in the time interval of interest. A typical example are contact conditions in constrained mechanical systems that can be formulated as unilateral constraints for the position and velocity coordinates. We discuss these singularities in detail for a simple m...

A challenging topic in the field of planetary rover simulations is the modeling of the contact between the rover and its environment. Multibody simulation models are used to represent the kinematic structure of a wheeled rover, but its interface with the environment relies on sand-wheel contact dynamics. A new advanced contact model is presented and tuned according to single wheel experiments b...

This paper presents a modular method for 3D dynamic simulation of wheeled mobile robots (WMRs). Our method extends efficient dynamics algorithms based on spatial vector algebra to accommodate any articulated WMR configuration. In contrast to some alternatives, our method also supports complex, nonlinear wheel-ground contact models. Instead of directly adding contact forces, we solve for them in...

This paper presents the development of an accelerator for the real-time simulation of wheelrail contact laws (Hertz and Fastsim), which would enable the use of hardware-in-the-loop for experimental studies of the latest active control technology for wheelset stabilization and steering. The complex wheel-rail contact laws are implemented using a single FPGA chip that outperforms modern general-p...