  Autonomous electric vehicles are being widely studied nowadays as the future
technology of ground transportation, while the autonomous electric vehicles
based on conventional powertrain system limit their energy and power
transmission efficiencies and may hinder their broad applications in future.
Here we report a study on the energy consumption and efficiency improvement of
a mid-size autonomous electric vehicle driven by in-wheel motors, through the
development of a numerical energy model, validated with the actual driving data
and implemented in a case study. The energy analysis was conducted under three
driving conditions: flat road, upslope, and downslope driving to examine the
energy consumption, with the energy-saving potential of the in-wheel-motor
driven powertrain system systematically explored and discussed. Considering the
energy recovery from the regenerative braking, energy consumption and
regenerated energy were calculated in specific driving cycles based on vehicle
dynamics and autonomous driving patterns. A case study was conducted using the
baseline electric vehicle driving data in West Los Angeles. It was found that
an in-wheel motor driven autonomous electric vehicle can save up to 17.5% of
energy compared with a conventional electric vehicle during the slope driving.
Using the efficiency maps of a commercial in-wheel motor, the numerical energy
model and validated results obtained from this study are in line with actual
situations, and can be used to support sustainable development of more
energy-efficient autonomous electric vehicles in the future.

Robotics;Systems and Control;Systems and Control