A review of continuous contact-force models in multibody dynamics

A review of the current use of multibody dynamics methods in the analysis of the dynamics of vehicles is given. Railway vehicle dynamics as well as road vehicle dynamics are considered, where for the latter the dynamics of cars and trucks and the dynamics of single-track vehicles, in particular motorcycles and bicycles, are reviewed. Commonalities and differences are shown, and open questions and challenges are given as directions for further research in this field.

https://link.springer.com/content/pdf/10.1007/s11044-020-09735-z.pdf

State-of-the-art and challenges of railway and road vehicle dynamics with multibody dynamics approaches

In this investigation, a closed-chain kinematic model for two-wheeled vehicles is devised. The kinematic model developed in this work is general and, therefore, it is suitable for describing the complex geometry of the motion of both bicycles and motorcycles. Since the proposed kinematic model is systematically developed in the paper by employing a sound multibody system approach, which is grounded on the use of a straightforward closed-chain kinematic description, it allows for readily evaluating the effectiveness of two alternative methods to formulate the wheel-road contact constraints. The methods employed for this purpose are a technique based on the geometry of the vector cross-product and a strategy based on a simple surface parameterization of the front wheel. To this end, considering a kinematically driven vehicle system, a comparative analysis is performed to analyze the geometry of the contact between the front wheel of the vehicle and the ground, which represents a fundamental problem in the study of the motion of two-wheeled vehicles in general. Subsequently, an exhaustive and extensive numerical analysis, based on the systematic multibody approach mentioned before, is carried out in this work to study the system kinematics in detail. Furthermore, the orientation of the front assembly, which includes the frontal fork, the handlebars, and the front wheel in a seamless subsystem, is implicitly formulated through the definition of three successive rotations, and this approach is used to propose an explicit formulation of its inherent set of Euler angles. In general, the numerical results developed in the present work compare favorably with those found in the literature about vehicle kinematics and contact geometry.

A Multibody System Approach for the Systematic Development of a Closed-Chain Kinematic Model for Two-Wheeled Vehicles

Investigation on parallel hybrid electric bicycle along with issuer management system for mountainous region

This paper presents a novel haptic support system for braking control in road bicycles. The basic idea is to provide a direct indication of the wheel deceleration to the rider in form of a brake lever vibration. The more intense the vibration, the closer the rider is to the threshold safe deceleration. This enables an efficient information transfer and an easy, safe deceleration. The paper presents the rationale and the proposed system. The performance is assessed through a number of experimental tests, showing that the presence of the haptic feedback enables the rider to brake more safely and more consistently than without haptic feedback.

A haptic-based, safety-oriented, braking assistance system for road bicycles

Electric bicycles have undergone a real boom in recent years and represent an important part in the area of sustainable mobility. In order to ensure long-term acceptance, a permanent improvement of safety is very important. This is the starting point for the interdisciplinary research project BikeSafe. It aims at the development of an active braking dynamics assistance system. This system targets both critical situations front wheel lockup and nose-over (falling over the handlebars). This paper presents a method by which the addressed critical driving situations can be simulated in road tests while ensuring physical integrity of human test driver.

Development of a Braking Dynamics Assistance System for Electric Bicycles: Design, Implementation, and Evaluation of Road Tests

The global spread of Electric Bicycles (EBs) is increasing more and more. In addition to supporting the ease of cycling, the electric energy available can also be used for innovative braking control systems. The project BikeSafe picks up on this idea and aims at developing an active Braking Dynamics Assistance system (BDA) for EBs equipped with hydraulic brakes. A simulation model taking into account all substantial braking dynamics influences is necessary for the model-based design of the BDA. This paper presents a Multi-Body Model (MBM) of a front suspension bicycle and a passive rider. This MBM has been experimentally validated for in-plane braking dynamics using road tests. It has real-time ability and can therefore be used as a virtual representation of the plant for the model-based design process of the BDA.

Design and validation of a multi-body model of a front suspension bicycle and a passive rider for braking dynamics investigations

For conventional and electrified bicycles (EB) there are two dangerous braking situations that could be addressed by electronic assistance systems similar to motorcycles: bicycle nose-over and front wheel lockup. The publicly funded research project “BikeSafe” at Pforzheim University, Germany, uses analytical methods, simulation models and a test bike to investigate these critical braking situations and to set up a prototype system to avoid them. Frequently and wrongly front wheel lockup is seen as the reason for bicycle nose-over — two completely different phenomena. However, under certain conditions both can appear at the same time. After a brief presentation of the “BikeSafe” project, this paper deals with the conditions and parameter settings under which these critical situations occur. Findings of an analysis using analytical vehicle dynamics approaches are presented and compared with results from literature and simulations. Full understanding of these phenomena is a prerequisite for the development of a functional prototype assistance system.

Conditions for nose-over and front wheel lockup of electric bicycles

In-depth analysis of bicycle hydraulic disc brakes

Electric bicycles have undergone a real boom in recent years and play an important role in the area of sustainable mobility. In addition to assisting the rider while accelerating the bicycle, the available electrical energy also offers the possibility to deploy safety systems to reduce the risk of accidents. For instance, active safety systems could help to avoid two major critical braking situations for single-track vehicles: front wheel lockup and nose-over (i.e., falling over the handlebars). An essential prerequisite for the development of such systems is a thorough understanding of tire effects on bicycle dynamics. To date, there are only very few scientific studies concerning bicycle tire characteristics. Thus, test runs on an inner drum tire test bench have been performed to measure vertical and longitudinal characteristics of a typical trekking bike tire. This article presents the main findings such as vertical stiffness and contact patch geometry depending on wheel load and inflation pre...

Jürgen Wrede

Papers

Development of a Braking Dynamics Assistance System for Electric Bicycles: Design, Implementation, and Evaluation of Road Tests

Design and validation of a multi-body model of a front suspension bicycle and a passive rider for braking dynamics investigations

Conditions for nose-over and front wheel lockup of electric bicycles

In-depth analysis of bicycle hydraulic disc brakes

Vertical and Longitudinal Characteristics of a Bicycle Tire