Motorcycle dynamics is characterised by the presence of modes of vibration that may become unstable and lead to dangerous conditions. In particular, the weave mode shows large yaw and roll oscillations of the rear frame and out of phase oscillations of the front frame about the steer axis. The presence of the rider influences the modes of vibration, since the mass, stiffness and damping of limbs modify the dynamic properties of the system; moreover, at low frequency the rider can control oscillations. There are few experimental results dealing with the response of the rider in the presence of large oscillations of the motorcycle. This lack is due to the difficulty of carrying out measurements on the road and of reproducing the phenomena in the laboratory. This paper deals with a research programme aimed at measuring the oscillations of the rider’s body on a running motorcycle in the presence of weave. First, testing equipment is presented. It includes a special measurement device that is able to measure the relative motion between the rider and the motorcycle. Then the road tests carried out at increasing speeds (from 160 to 210 km/h) are described and discussed. Best-fitting methods are used for identifying the main features of measured vibrations in terms of natural frequencies, damping ratios and modal shapes. The last section deals with the comparison between measured and simulated response of the motorcycle–rider system in weave conditions; good agreement was found

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Most of researches in the field of bicycle dynamics deal with auto-stabilization and rider control by means of steer-torque and lean-torque. Bicycle models composed by rigid bodies with thin wheels making point contact with the road and rolling without any slip are suited for carrying out these studies. Numerical analysis of stability by means of these models leads to the capsize, castering and weave modes, which make it possible to understand many aspects of bicycle dynamics. However, some high performance bicycles at high speed show dangerous wobble oscillations. Cyclists’ experience and recent researches highlight that wobble phenomena are related both to tire properties and to fork and frame compliance. Since structural compliance in dynamic conditions generates vibrations, this paper focuses on the study of structural vibrations of high performance bicycles with the modal analysis approach. To isolate the effects of frame and fork compliance, four particular bicycles are considered, they are built assembling a pair of wheels, two forks (fork A and B) with the same shape but different structures and materials and two frames (frame A and B) with the same shape but different structures. Preliminary road tests showed that bicycles made with components A are more prone to wobble oscillations. In order to have a better comprehension of the different influence of fork and frame compliance, first the two forks (with the front wheel) are modally tested with the steer tube locked to a very stiff structure, then, the whole bicycles are tested. Modal analysis is carried out with the impulse method, for the analysis of each bicycle 60 FRFs are measured. The results of modal analysis are presented and the influence of identified modes on bicycle stability is discussed. An important issue of modal analysis of vehicles is the correlation between modal tests carried out in the laboratory and bicycle behavior on the road. When the vehicle is tested in the laboratory, additional constraints are added to guarantee equilibrium, but centrifugal forces are not present, because the vehicle is stationary. Since the analysis of the equations of linearized dynamics shows that the stiffness matrix includes a part due to centrifugal effects, the additional stiffness terms due to constraints in laboratory tests can be assumed to be equivalent to the centrifugal terms of the stiffness matrix at a certain speed. Details and limits of this equivalence are presented and discussed in the paper.

Abstract-The paper describes the new portable driving simulator for powered two wheelers (PTW) designed and built in 2011 at the University of Padova. The simulator is mainly to train riders and to study their behaviors in different scenario, but also to investigate different design choices on PTW dynamics, to develop and test new electronic devices and advanced driver assistance systems. Several examples of telemetry logged from the simulator are presented and discussed to highlight how the simulator captures the most important PTW dynamics, such as the counter-steering, tire skidding, weave/wobble instability, etc.

A new commercial software package for the minimum-time optimal-control simulation of motorcycles, named OMS (Optimal Maneuver Simulation), is presented. OMS integrates a set of tried-and-tested components (vehicle and road models, solver) in a single software package that allows a team new to minimum-time simulation to kick-start this activity. A typical use case of OMS is performing a sensitivity analysis on some vehicle parameters to assess the effect of different vehicle configurations on the lap-time performance on a given track.