# A Survey: Future Smart Cities Based on Advance Control of Unmanned Aerial Vehicles (UAVs)
## 4 Control Theory Progress for UAVs  
The availability of low-cost inertial measurement units (IMUs) has enabled the development of various miniature UAVs. One of the most recent and interesting UAVs is the twin-rotor MIMO system (TRMS), which is capable of vertical takeoff and landing (VTOL). UAV systems have a hovering capability that makes them superior to fixed-wing systems, which cannot hover and are unsuitable for environments that require stationary or quasi-stationary flights. UAV systems have extensive military and civil applications and have attracted significant funding and research interest from various communities. In the last decade, several researchers have completed projects on UAVs. These systems have found utility in a wide range of applications including surveillance, aerial photography, building exploration, climate forecasting, bridge inspection, 3D mapping, swarm missions, and numerous other use cases [19; 34]. UAVs have become increasingly important in a variety of control applications due to their flexibility, mobility, and ability to operate in remote or hazardous environments. UAVs have versatile applications, encompassing surveillance, search and rescue operations, inspection tasks, mapping initiatives, agricultural practices, and delivery services. UAVs are also useful in industrial control applications, such as monitoring and controlling chemical plants or power generation facilities [35; 36]. One of the main advantages of UAVs for control applications is their ability to provide real-time data and feedback. UAVs can be \begin{table}
\begin{tabular}{c c c c c} \hline \hline
**Characteristics** & **Fixed Wing** & **Rotary Wing** & **Hybrid** \\ \hline Energy efficiency & High & Low & High \\ Flight system & Complicated & Simple & Complicated \\ Landing & Conventional & Vertical & Vertical \\ Autonomy & No & Yes & Yes \\ Hovering & No & Yes & Yes \\ Power supply & Battery, fuel & Battery & Battery, fuel \\ Endurance & 60–3000 m & 6–180 m & 180–480 m \\ Payload & 1000 kg & 50 kg & 10 kg \\ Weight & 0.1–400,000 kg & 0.01–100 kg & 1.5–65 kg \\ \hline \hline \end{tabular}
\end{table} 
Table 2: Characteristics overview of UAVs [33]. \begin{table}
\begin{tabular}{c c c c c c} \hline \hline
**UAV Type** & \multicolumn{2}{c}{**Applications**} & \multicolumn{2}{c}{**Advantages**} & \multicolumn{2}{c}{**Drawbacks**} \\ \hline  & & & & * & hovering & \\  & & & & * & large payload & \\ \(\bullet\) & Rotary Wing & \(\bullet\) & supply drops & \(\bullet\) & great maneuverability & \\ \(\bullet\) & (helicopter) (c) & \(\bullet\) & inspection & \(\bullet\) & ease of use & \\  & & & & * & efficient camera control & \\  & & & & * & vertical takeoff and landing (VTOL) & \\ \hline  & & & & & * & launching \\  & & & & \(\bullet\) & large area coverage & \\ \(\bullet\) & Fixed-Wing (d) & \(\bullet\) & structural inspection & \(\bullet\) & high speed & \\ \(\bullet\) & area survey & \(\bullet\) & great stability & \(\bullet\) & challenging to fly \\  & & & \(\bullet\) & safer recovery from & \\  & & & & motor power loss & \(\bullet\) & less efficient area mapping \\ \hline \hline \end{tabular}
\end{table} 
Table 1: _Cont._equipped with a variety of sensors, including cameras, thermal imagers, LiDAR, and gas sensors, among others, that can provide data on temperature, pressure, air quality, and other environmental variables. This data can be used for control applications, such as monitoring the progress of a search and rescue mission, detecting gas leaks in a chemical plant, or assessing the health of crops in an agricultural field [37]. One important benefit of nonlinear UAVs is their ability to operate in complex, dynamic environments. Nonlinear control algorithms can help UAVs adapt to changing conditions and respond quickly to unexpected disturbances, allowing them to navigate through cluttered or congested environments, avoid obstacles, and track moving targets with greater precision [38].