Mechanical design of Autonomous Robot for Last Mile Delivery

Autonomous Delivery robots are an emerging technology aimed at resolving complexity existing in the last phase of transportation to the final customer. Their application inserts in a complicated context in which a growing emerging awareness of a need of improvement of urban mobility is forcing companies to think to smarter and greener ways to complete deliveries. For these reasons, these fully electric vehicles are thought to operate on pedestrians’ domain avoiding, and simultaneously limiting, the effects of last mile delivery on traffic. Delivery accounts for 25% of all urban emissions and 20% of urban traffic is due to shipments. The fundamental purpose of this thesis is to design a fully electric traction system that is able to allow the vehicle to deliver parcels in several districts of the city, overcome architectural barriers, have a sufficiently high autonomy without being a hindrance for pedestrians and therefore well integrated with the surrounding environment. From this point of view, mechanic requirements and constraints are evaluated. Since there is no published data on delivery robots application, hypothetical driving cycles were employed on common drone routes. It is based on the place of start and end of the delivery services and on the basis of the route simulations, the factors contributing to the energy demand and its variation have been analyzed. As a result of this examination the propulsion system and energy source are selected. The idea conceived for this delivery robot is to adopt a system of four in-wheel motors that allow independent management of the torque and the possibility of steering each individual wheel. The steering and suspension systems will also be analyzed, designed not only for their natural function, but also to allow safety and adaptability to the movement of pedestrians. To ensure the integrity of the parcels and the possibility of travelling uneven roads, simulation of the dynamic response of the vehicle’s body is conducted and vertical accelerations respect to the relative displacement of the suspension where analysed. The drone is also equipped with four servo motors on each driving wheel in order to ensure the independent steering and the possibility of achieving all types of curvature except horizontal translation for reasons of encumbrance. The result of the project is Pacci, a unique concept of delivery robot, modular and capable of transporting a large number of packages, as well as adapting the dimensions of the compartments to the user's needs. All this by exploiting existing urban infrastructures such as the bus line, modified exclusively in the back with a luggage carrier for drone transportation, to reach different areas of robot competence and to further reduce polluting emissions.