Modelling of two-wheeler braking and
turning performance
Background
There is nowadays a growing interest within the EU for increasing the use of two-wheelers
(bicycles, electric bicycles, electric mopeds/motorcycles, mopeds, motorcycles) for shorter
transports within the cities. Accordingly, improving the safety for the riders will grow in
importance both with regards to the road infrastructure and the maintenance, but also
regarding the vehicle’s performance. From the perspective of Vehicle Dynamics and Accident
Prevention, the braking and turning performances are of major importance for twowheelers. And this is something which is decided both by the vehicle design and how the
rider operates the vehicle.
Bicycles are typically designed with two of each other independent brake systems operating
on one wheel each. In the European Bicycle Safety Standards, there are specific requirements
regarding the stop distance during various weather conditions dry and wet, when activating
the brakes on both of the wheels or only on the front wheel.
The number of electrical assisted bikes (EPAC’s) is increasing. They are an attractive
alternative for more people, since they facilitate longer commuting distances per bicycle. New
technology, as anti-block (ABS) brake systems, is in particular motivated for the EPACs,
because of the increased need due to higher average speed and the increased additional cost
considered reasonable because of the higher level of technology in this category of bicycles.
From the moped/motorcycle side, there is also a trend to try electric propulsion and to develop
towards vehicles specialized for urban traffic.
CycleEurope and Chalmers are interested in developing bicycle design for improved safety.
Many accidents with two-wheelers are single accidents, which is addressed by improving the
performance of the two-wheeler itself. Other accidents involve a larger vehicle (typically a
passenger vehicle or a truck). The latter accidents can be addressed by developing the larger
vehicle, typically with environment sensing based functions, such as Automatic Emergency
Braking. In order to develop such functions, it is important to be able to predict, in terms of
dynamic models, how two-wheelers are operated.
Chalmers is involved in EU cooperation where simulation models for traffic reconstruction
are developed. Chalmers part in these project is to model the operation of two-wheelers.
The thesis has:
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Scientific relevance, especially regarding how novel vehicles (cross-over, such as ebikes and e-motorcycles) are driven.
The department can see two-wheelers technologies as an emerging or novel area.
A need for this research is foreseen, both for manufacturers of these vehicles and for
society, which needs to follow the development with legislation and type certification
of novel vehicles.
The need of merging knowledge from Vehicle Dynamics and Accident Prevention is
high, since braking and turning performance is decided both by the vehicle design and
how the rider operates the vehicle.
Problem motivating the project
Vehicle design
o Approximately 6 % of the single bicycle accidents in Sweden (Swedish Transport
Administration, 2014:035, Safer Cycling) are caused by panic braking, causing the
rider to fall over the handlebar down on the street or against another vehicle involved
in the collision. The bicycle rider is often seriously injured. This is called “Problem 1”
below.
o The blocking of the front wheel is in particular dangerous when riding in curves and
with low friction. The rider is falling on the ground inwards. This is called “Problem
2” below.
Vehicle operation
o Two-wheelers accidents can be mitigated also through design of larger vehicle
(typically a passenger vehicle or a truck), but the knowledge of how two-wheelers is
not well enough known for developing and verification of safety functions in the
larger vehicles.
Envisioned solution
o EBD/ABS-like brake function that:
o Reduces brake force on front wheel (EBD-like, for “Problem 1” above)
o Avoids locking of the wheels (ABS-like, for “Problem 2” above)
o Safety systems for larger vehicle to care of two-wheelers
Objective (or Research Question)
o How to design an EBD/ABS-like brake functionality for bicycle/electric bicycle?
o How does two-wheelers of various types operate in traffic situations? Including
braking and turning. With and without novel EBD/ABS-like brake function.
Deliverables
o Design of an EBD/ABS-like brake functionality for bicycle/electric bicycle that
addresses “Problem 1” and “Problem 2” above.
o Model of two-wheelers (with its rider) of various types operate in traffic situations.
Braking and turning.
Stretched target: Prototype/Experiments
Sketch of activities
The time plane will probably include:
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Information search
Brake system design (requirement setting, design, verification of design)
Vehicle & rider modelling (for generic two-wheelers and specialization to different
two-wheeler types, verification of models)
Administrative
The thesis is a cross-divisional thesis, which means that two divisions are involved from
Applied Mechanics. There shall be two students, each with examiner from each of these
departments. However, it shall be one report. There will be a payment to each student of 25
kSEK. YFO will follow-up the thesis project, during its whole duration.
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Number of points: 30 points (nominally 20 weeks)
Starting date: First quarter of 2014
Suitable number of students: 2
Suitable/required students background: Automotive engineering and Dynamic modelling
Responsible subject/research group at Chalmers: Two groups since “cross-divisional MSc
thesis”:
o Vehicle Dynamics at Division for Vehicle Engineering & Autonomous Systems
o Accident Prevention at Division for Vehicle Safety
Examiners:
o Bengt Jacobson, bengt.jacobson@chalmers.se, +46 31 772 1383
o Marco Dozza, marco.dozza@chalmers.se, +46 31 772 3621
Proposed supervisors:
o Bengt Jacobson, bengt.jacobson@chalmers.se, +46 31 772 1383
o Marco Dozza, marco.dozza@chalmers.se, +46 31 772 3621
o Cycleurope Sverige AB, Claes Alstermark, claes.alstermark@monark.se,
+46 340 86248, +46 70-67 17 696
Involve organisations, except Chalmers:
o Cycleurope Sverige AB
Physical location: At Chalmers with visits to Cycleurope Sverige AB, Varberg
References
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Gunnar Olsson and Petter Hedström, Brake performance and stability for bicycles,
Trafikverket, 2013
Jonathan Rice and Bengt Jacobson, Implications of emerging lightweight urban personal
vehicles on traffic safety, based on forecasts of technology solutions for vehicles,
Chalmers University of Technology, Research report 2014:10, ISSN 1652-8549, , 2014.