reliability of drone delivery network, battery
consumption, and delivery time windows. As in
(Torabbeigi et al., 2018), the reliability concerning
drone failure is considered. They assume the drone
failure follow an exponential distribution. In (Cheng
et al., 2020), the robust scheduling is proposed by
considering the wind condition uncertainty. In (Kim
et al, 2020), the drone operation planning model is
designed by considering the demands of each
destination and also the battery level of the drone.
Each drone is assigned to either deliver the parcels or
recharge the battery. In the operation planning of
(Torabbeigi et al., 2020), the battery consumption rate
of drones is modeled depending on the carrying
payload. The drones pick the parcels from the depot,
deliver to customers and then return to the depot.
(Dukkanci et al., 2020) studies the energy
consumption of drone according to its speed function.
For the delivery time window constraint, (Han et al.,
2020) considers a vehicle routing problem by
satisfying the time window. In (Huang et al., 2020),
the parcel delivery system which considers the
cooperation of public transport and drones is
considered. They model the system characteristic
including the delivery time, energy consumption and
battery recharging.
For the simplified model of flying taxi, we have
to select some constraints from drone operations to be
considered. We will concentrate to the battery
consumption function, battery recharging, and time
window of demands, but ignore other constraints in
this step.
1.2 Taxi Demand Scheduling
We study how to manage taxi demands efficiently in
this part. The passengers require the taxis to pick up
in the specific location and specific time window.
Then, the taxis bring them to the destination in the
limitation of tardiness.
A classical problem in the domain of operations
research, which concerns the taxi demand scheduling,
is the vehicle routing and scheduling problem with
time window constraints or VRSPTW. This problem
needs to find the minimum-cost vehicle routes to
serve a set of customers by satisfying the vehicle
capacity constraints. Moreover, each customer must
have a service in the specific available time window.
The VRSPTW is an NP-hard problem for which
heuristic algorithms are widely used. (Solomon,
1987).
We can also model the taxi demand scheduling
problem like the fleet management problems as in
(Bielli et al., 2011). It presents different mathematical
models for variant transportation modes and
characteristics. In (Glaschenko et al., 2009), it
considers a multi-agent approach to real-time
scheduling to be able to re-schedule and update
schedule in real time. The orders have to be matched
to drivers, vehicles, resources and work practices.
The schedule must ensure fair and proportional jobs
distribution for drivers. In (Shen et al. 2017), the
dispatching system to design a demand-responsive
schedule is considered. It consists of a planning of
travel path (routing) and customer pick-up and drop-
off times (scheduling) by considering certain
constraints such as vehicle capacity limitation and
available time windows.
The profit of taxi service is an important objective
for the business. The fare of general taxi services is
calculated from a base rate (for some first kilometers
as initial charge), a distance rate (multiply to the next
kilometer count), and a minute rate (multiply to the
minute count of the waiting time). However, the fare
of flying taxi will be calculated from only the base
rate and the distance rate. We ignore the congestion
on the low altitude air traffic in this step.
According to the related work, we design a
simplified model of flying taxi scheduling problem. It
is presented in Section 2. Some delivery drone
specifications such as the vertical take-off and
landing, operating hours, recharging time, battery
capacity, power consumption rate will be borrowed
from the literature for the experiments. We need to
maximize the working time that the flying taxis serve
the clients on the selected demands and it is used to
be the objective function in our work. In Section 3 and
4, two metaheuristics, which are a genetic algorithm
and a simulated annealing, are presented. We apply
these two algorithms to optimize the scheduling
problem. The computational results on fifteen
generated instances are illustrated in Section 5.
Lastly, the conclusion and the future work are
presented in Section 6 and 7, respectively.
2 FLYING TAXI SCHEDULING
OPTIMIZATION MODEL
In this section, an optimization model for the flying
taxi scheduling problem will be presented. The
simplified flying taxi characteristics are designed
from the commercial delivery drones in several
research works. We assume that the flying taxis
operate to serve the customers as same as the drone
service for transporting the parcel from an origin to a
destination. The main operating time of a task is to