  This research has addressed three critical challenges inherent in the
implementation of drone delivery systems, namely, optimizing battery charging
station placement, solving the shortest path problem for drones within their
single battery charge travel distance, and efficiently scheduling multiple
drones across numerous warehouses and delivery locations with diverse demands.
The study has leveraged a 2D grid model with obstacles, providing a practical
foundation extendable to a 3D grid for accommodating complex structures. For
battery station placement, the Miller-Tucker-Zemlin subtour elimination method
has been applied to avoid the formation of charging station clusters. Future
research directions involve the integration of these cases into a holistic
solution, exploration of three-dimensional space, and the pursuit of bi-level
optimization considering the interdependence of battery station placement and
shortest path determination. This study contributes to the emerging field of
drone delivery systems by addressing key optimization challenges and paving the
way for comprehensive, integrated solutions.
