## 1 Introduction  
New technologies enable the development of mechatronic components and mechatronic systems found in many industries today. These mechatronic systems are also crucial for the development of unmanned aerial vehicles (UAVs). Since UAVs are no longer tied exclusively to military use, as they were in the past, their use in the civilian sector contributes to numerous applications and consequently increases in the market. Nowadays, UAVs can be used in many sectors such as surveillance [1], agriculture [2], construction [3], and many others. UAVs are also used in missions that involve the delivery of medical supplies, such as Zipline aircraft [4]. Depending on the applications, different types, different sizes, and various power ranges of aircraft are used. The general division can be made between fixed-wing aircraft and rotary-wing aircraft, so-called rotocopters. In addition to these two main types of UAVs, hybrid aircraft [5] and bioinspired aircraft, such as the Bat Bot (B2) [6], a biologically inspired flying machine, have also been increasingly investigated recently. In missions that require vertical and stationary flight, rotocopters are mainly used. There are two subtypes of rotocopters, aircraft with fixed-pitch propellers, so-called multirotors, and aircraft with variable pitch propellers whose typical representatives are helicopters. The multirotor type of UAV can perform a vertical take-off and landing (VTOL), be stationary in the air, and perform movements at a moderate speed in a three-dimensional (3D) space. This makes this type of aircraft suitable for many specific applications, such as the inspection of wind turbine blades [7] or transmission lines [8]. From a control point of view, the multirotor type of UAV is an inherently unstable, nonlinear, and multivariable system. Such systems must necessarily include a flight controller (FC) unit that sends control signals to the aircraft propulsion system. Control methods for this type of aircraft are highly investigated, for example, in papers [9; 10; 11]. The multirotor configurations are determined by the design of the aircraft propulsion system consisting of N rotors. The rotors in the standard versions are actually the electric propulsion units (EPUs) which consist of a fixed-pitch propeller, brushless DC (BLDC) motor, and electronic speed controller (ESC). There are EPU components on the market that can be up to 10 kW per unit. Certain manufacturers additionally offer components intended for air transport with a power of a few tens of kW per unit [12]. Conventional multirotor configurations consist of an even number of rotors arranged in one or more parallel planes. The most common design is a four-rotor aircraft, better known as a quadrotor or quadcopter. The characteristic of conventional configurations is that they are underactuated, and it follows that such systems are also strongly coupled. This is disadvantageous in missions that involve precise and complex movements. Namely, conventional configurations need to change orientation in order to move in a 3D space. This can be overcome with non-planar geometric arrangements of multirotor configurations, such as OTHex aircraft [13]. By selecting the adequate geometric arrangement of the rotors, independent control of the system for each degree of freedom can be achieved, which enables decoupling of position control and orientation control. So far, fully actuated configurations with six passively tilted rotors are the most researched. The control of such systems [14] is considered, and full-pose tracking control for a fully controlled hexarotor with passively tilted rotors is presented in [15]. Since the performance of a multirotor aircraft depends on the parameters of the propulsion system, as seen in papers [16; 17], the procedures of estimation, modeling, and the optimization of the parameters for a fully actuated hexarotor with tilted rotors are presented. Furthermore, fully actuated multirotor configurations are of interest to the research from the aspect of fault-tolerant control.