Model Motion and Energy Usage of Multi-trailer Vehicles in Modelica

Thesis background

Environmental issues, consumers expectations and the growing demand for freight transport have created a competitive environment in providing better transportation solutions. Conceptual and optimization-based vehicle design using mathematical models help finding cost- and energy-efficient solutions and eventually faster market adaptation. Therefore, mathematical models with acceptable levels of fidelity must be developed to facilitate the conceptual design and performing optimization, for example, to understand what vehicle components are suitable for US transport fleet market and how they are different from Asia and Europe applications.

Modelica language offers modular physical modelling. It is tool-independent and there are many open-source libraries which make building models with different levels of fidelity possible. In addition, models are open, so that the mathematical equations are visible to users, providing a good autonomy for updating the existing libraries and developing new models.

Problem motivating the project

Most of the existing multi-trailer mathematical models are not modular and the level of fidelity of the models cannot be changed in a straightforward way. However, those properties of the mathematical model (modularity and flexible change of fidelity) are necessary for vehicle conceptual design and optimization for different design targets, applications, optimization cost and constraints.

Envisioned solution

The envision solution is mathematical models in Modelica that can be used to simulate motion of multi-trailer vehicles and energy usage of the entire system together with different motion support devices. The models should be modular, i.e., it should be possible to change a low fidelity subsystem model with a high fidelity one to capture the physical phenomena needed for the given application.

Objective

Define different typical simulations where the model should be useful.

How to model the multi-trailer vehicle in Modelica with the purpose of compoent and fleet transport missions optimization ?

How to make the model modular?

How to model different subsystems and motion control devices, e.g. brake actuators, suspension, electrically driven axles, steering, cooling systems, etc, with lowest reasonable fidelity levels with reasonable computational loads but with interface (variables, signals, parameters) extendable to higher?

What are the important phenomena and physical behaviours that change or cannot be captured by altering the model fidelity?

Deliverables (flexible)

• Modelica models of multi-trailer road vehicles. It should be possible to change number of units, e.g., add/remove semi-trailers to/from the models.
• Models of powertrain and longitudinal dynamics.
• Models for lateral and roll motion.
• Simple modular models of motion support devices (with one or two acceptable levels of fidelity). Motion support devices include but not limited to brake system, electric driven axles, steerable axles, and suspension system.
• The Modelica model should be automatically parameterized reading a model-independent vehicle parameter file.
• Making the comparison of the simulation results with other available in-house tools as well as the available real-world test data, both in terms of energy consumption and motion.
• Several of performance bases standard measures [1] should be analysed. Challenges, and potentially proposed development steps should be listed.
• Some of the models should be exported as functional mock-us to another environment (such as Matlab or Python) and re-parametrization and change of model fidelity should be tested in the new environment

Limitations

The level of fidelity of subsystems models should be limited

Student background

Talented master students in Automotive, Mechanics, Mechatronics or Engineering Physics, with some knowledge of Modelica and programming.

Supervision and examination

Volvo Group Truck Technology, Advanced Vehicle Engineering/Vehicle Analysis.

Chalmers University of Technology, Department of Mechanics and Maritime Sciences, Vehicle Engineering and Autonomous systems, Vehicle Dynamics.

Suitable number of students: One or two

Number of credits: 30 points per student (nominally 20 weeks)

Starting date: January 2023

Resources: The student(s) will be provided with similar available Modelica models and real-world test data, Modelica tools and student licenses.

Stakeholder: Volvo Group Truck Technology (VGTT)

Responsible subject/research group at Chalmers: Vehicle Dynamics

Physical location: Volvo Group Truck Technology, Gothenburg.

Contacts

Toheed Ghandriz: [email protected]

Sofi Sjögren: [email protected]

References

[1] Research project , Performance Based Standards II, https://research.chalmers.se/project/8350