Researchers at Chalmers University of Technology in Sweden have developed tools to help electric delivery vehicles navigate to reduce energy use and increase range.
By focusing on energy use rather than distance travelled the researchers were able to develop an algorithm that leads to energy savings of up to 20 percent. The new algorithm for learning and planning the optimal path of electric vehicles is so efficient that it is already being used by Volvo Group.
“We have developed systematic tools to learn optimal energy usage. Additionally, we can ensure that electric vehicles are not running out of battery or charging unnecessarily in complex traffic networks,” said Balázs Kulcsár, professor at the Department of Electrical Engineering at Chalmers University of Technology, and leader of the research.
The research is the latest result from a joint project between Chalmers and Volvo Group that investigates how electric vehicles can be used for distribution tasks.
Shortest distance not always best
In the study, the researchers investigated how a fleet of electric trucks can deliver goods in a complex and crowded traffic network. The challenge was to develop the best routing for vehicles carrying household goods, such as groceries or furniture to several different addresses.
By working out the optimal order to deliver to customers, the vehicles can be driven for as long as possible without needing to interrupt the work to recharge unnecessarily. Route planning for electric vehicles has normally tended to assume that the lowest mileage is also the most efficient, and therefore focused on finding the shortest route as the priority.
Kulcsár and his colleagues focused instead on overall battery usage as the key goal, and looked for routes with the lowest possible energy consumption.
“In real traffic situations a longer distance journey may require less energy than a shorter one, once all the other parameters that affect energy consumption have been accounted for.” Kulcsár explained.
Reduction in energy consumption
The researchers modeled the energy consumption of distribution trucks moving in a city by looking into many factors – speed, load, traffic information, how hilly different routes were, and opportunity charging points.
The energy consumption model was then entered into a mathematical formula, resulting in an algorithm for calculating a route that allows the vehicles to make the deliveries using as little energy as possible.
If charging is needed out on the road, the vehicle can save time by taking the most energy efficient route to a fast-charging point. By accounting for extra factors such as these, the researchers’ new method allowed the vehicles to reduce their energy consumption by between five and 20 percent.
Because the electric delivery vehicles operate in complex real-world situations, there can often be unforeseen complications that are difficult to account for even if the algorithm is accurate from the beginning. The energy usage forecasts will be further optimized through machine learning, with data collected from the vehicles being sent back to the tool for further input and analysis.
“Taken together, this will allow us to adapt route-planning to uncertain and changing conditions, minimizing energy consumption and ensuring successful urban distribution.” Kulcsár said.
The full article detailing the research is Dynamic Stochastic Electric Vehicle Routing with Safe Reinforcement Learning, was published in the journal Transportation Research Part E: Logistics and Transportation Review. Balázs Kulcsár co-authored the study with Ivan Sanchez and Xiaobo Qu at Chalmers University of Technology in collaboration with Rafael Basso, senior researcher, Volvo Group.
The research was funded by Vinnova, project ELFORT I-II, and co-funded by Chalmers Transport Area of Advance.