Total Product Design
Group Dissertation





Design of an Autonomous Electric Trailer



Partnership with electric vehicle company Patrimony EV with the aim to design and simulate an electric trailer to extend the life of electric vehicles when towing.



KEY SKILLS





MATLAB and Unity Simulation



Electric Vehicle System



FDM 3D Printing



Project Management



CAD Modelling



OVERVIEW





BRIEF



This project was a partnership between a start-up company PatrimonyEV, with an initial aim to develop an electrically powered trailer. Current electric vehicles struggle to tow trailers for more than 100 miles due to the reduced amount of energy electric vehicles hold. Therefore, a powered trailer would allow users to travel equivalent distances with an electric vehicle as with one using an internal combustion engine.



DELIVERABLES



  • 120 Page Dissertation
  • 30 Minute Presentation
  • Physical Design and Testing


SOLUTION



Our team utilised MATLAB and Unity simulation to initially prove the concept would work successfully, then carried out physical testing using an internal combustion vehicle and a standard trailer to understand the scenario in more depth. A 1/10 scale model of the car and trailer was manufactured, as well as four potential vehicle control algorithms. In addition, extensive research was conducted on the CAN bus and how it could be used to control the car and trailer.



SOFTWARE USED





Siemens NX11



MATLAB



Unity



Cura



MATLAB SIMULATION





To quantify the benefits of using an electric powered trailer, the performance of an electric car towing an electric trailer was compared to that of an electric car towing a standard trailer. Therefore, a Simulink model of a Tesla Model 3 was created to act as the electric car, and simulations of a non-powered and powered trailer were created. Plotting these results graphically showed a clear increase in the state of charge using a powered trailer. After analysing the Simulink simulations, it was deduced that attaching a standard (unpowered) trailer to an electric vehicle drastically reduces the range of the electric vehicle. However, if the trailer has its own electric powertrain, this reduction in range is minimised, and the response of the electric vehicle to system inputs is reduced. This leads to a system with an extended range and a faster response time.



UNITY SIMULATION





A Unity model of a car and trailer system was created, with the end goal to create a Digital Twin of system. This utilises Unity’s inbuilt physics engine and in conjunction with an accurate representation of the 3D world, a digital twin, scale model, and simulation that can be accurately represented and visualised in the 3D space. Inside Unity, a C# script was created to control the power delivery for the electric vehicle model, converting the input acceleration into the rotational speed at the wheels.



REAL WORLD TESTING





To validate the scale model and simulations, accurate real-world data had to be collected. This was collected using a vehicle that towed an unpowered trailer. The vehicle and trailer were loaded with sensors (CAN Bus, Accelerometers, and Ultrasonic Distance Sensors) to record their relative characteristics. Representative situations such as acceleration, deceleration, left corners, right corners, and roundabouts were tested and evaluated. In addition to these situations, different vehicle setups were tested, including unloaded and loaded trailer testing with 5x22kg sandbags. The target was to validate the performance of the scale model testing platform against real-world data, enabling representative conclusions to be drawn and enhancing the development of an autonomous electric trailer.



SCALED MODEL TESTING





Car Model



Trailer Model



Hitch Model



Model Assembly





Faheem Aziz (MEng, DIS)



Product Design Engineer