Belted Safety Jacket: a new concept in Powered Two-Wheeler passive safety

Abstract Powered Two Wheelers (PTWs) offer a viable solution to reduce traffic congestion and promote personal mobility. However, vehicle characteristics and conspicuity issues lead to an overrepresentation of PTWs in accident statistics. This work presents an innovative approach for concept design of new passive safety devices and their development. The landscape of possible design solutions was examined with an in-depth analysis of the state of the art and with the use of conceptual design tools. Candidate solutions underwent a feasibility assessment and they were crossed-checked with the rider needs, identified via a specific on-line survey. The concept of a new passive safety device was born: a Belted Safety Jacket (BSJ). An initial assessment of the device effectiveness for the reduction of riders' injuries was performed by comparison of the main biomechanical indexes (HIC, Nijmax, Chest Deflection and Viscous Criterion) in a relevant accident configuration, reproduced in a virtual environment, with and without the device. Later a full factorial Design of Experiment (DOE) was carried out to understand the influence of the device geometrical variables (i.e. possible design parameters) on the biomechanical indexes. The results demonstrated that the integration of BSJ onto the vehicle has the potential to significantly reduce the occurrence of serious injuries during a PTW accident versus a car, since it prevents the contact of the rider with the opponent vehicle. The analysis of the accident kinematic with BSJ suggests that the device will be beneficial also in accidents with other vehicle types

E-bikers’ braking behavior: Results from a naturalistic cycling study

The number of e-bike users has significantly increased over the past few years and with it the associated safety concerns. In fact, e-bikes are faster than traditional ones and more prone to be in conflict with road users, so that e-bike riders may need to perform avoidance manoeuvres more frequently than traditional riders. Braking is the most common avoidance manoeuvre, but also a complex and critical task in emergency situations, since cyclists must reduce speed in a short time while maintaining their balance. The aim of this study is to understand the braking strategies of e-bikers in real-world traffic environment and to assess the road safety implications. This paper used data from the E-bikeSAFE naturalistic study to investigate 1) how cyclists use front and rear brakes during routine cycling and 2) whether this behaviour changes during unexpected conflicts with other road users.In most of events requiring a braking manoeuvre, cyclists used one brake at a time during routine cycling, favouring one of the two brakes according to a personal pre-established pattern. However, different cyclists exhibited different braking strategies and the favoured brake varied among cyclists (66% favoured the rear brake and 16% the front brake). Only a few cyclists (16%) did not show a clear preference,\ua0 using rear brake, front brake, or combined braking (both brakes at the same time) non-systematically, suggesting that the selection of what brake to use was based on the characteristics of the specific scenario that the cyclist experienced rather than personal preference.In a subset of unexpected conflicts, combined braking became more prevalent for most of the cyclists; still, when combined braking was not applied, cyclists continued to use the favoured brake of routine cycling. The kinematic analysis revealed that, when larger decelerations were required, cyclists more frequently used combined braking instead of single braking.The results provide new insights into the behaviour of e-bikers and support the development of safety measures including guidelines and best practices for the optimal use of front and rear brakes. The results may also inform the design of braking systems that may sreduce the complexity of the braking operation

Design and testing of a MRF rotational damper for vehicle applications

Adaptive dampers are an interesting solution for conjugating the necessity of controllable devices and low power consumption. Magneto-rheological fluids (MRF) can be profitably employed in adaptive dampers because of the significant variation of fluid parameters with magnetic field properties. This paper focuses on the design process of an innovative rotational MR damper specifically created to be placed in the front-wheel suspension of a compact car. The advantages of the rotational damper and the definition of the optimal design are described. The proposed damper significantly reduces several key problems associated with MR devices: the quantity of fluid required, the sedimentation of ferromagnetic particles in the suspension and the abrasion of the seals. In fact, with this solution, low average working pressure, low flow velocity through valves, a wide range of variable damping characteristics, and high durability of the damper can be achieved. Thanks to this innovative component, different new architectures for adaptive suspension systems can be developed to have a planar distribution of the suspension components with a consequent space optimization and size reduction in the vertical direction. © 2010 IOP Publishing Ltd

Design of a motorcycle steering damper for a safer ride

Powered-two-wheelers (PTWs) are increasingly popular because of their lower cost compared to cars, and therefore the riders' exposure risk is increasing. Due to their complex dynamics characterized by high non-linearity and inherent instability, PTWs are more difficult to control compared to four-wheeled vehicles. Wobble is a high-frequency instability mode affecting the steering assembly of the PTW, and which often causes the rider to lose control and crash when it occurs. In this paper, we present the design of a new motorcycle semi-active steering damper integrated into the steering column and utilizing a magnetorheological fluid (MRF) for variable damping torque. An analytical model of the concept was first used to perform the preliminary sizing, followed by concept validation using a 3D FE multiphysics magnetic-fluid analysis. The final innovative design offers several advantages compared to traditional steering dampers: (i) a wide range of adjustable damping torque values, with a multiplication factor up to 10 with a maximum electrical current of 2 A; (ii) total integration into the motorcycle steering column enabled by its axial design and limited radius; (iii) a simple chamber geometry that allows for easy manufacture; (iv) longer seal life due to the absence of direct contact between seals and the MRF