**2. System design of flooding disaster-oriented USV**

Although the parts of USVs have been applied in reality, the autonomy of these platforms is still so weak that most of them can only work under the control of operators. This makes them difficult to be used to verify some high-performance autonomous control algorithm. Thus, a new USV system equipped with different kinds of sensors and ground control system is designed and introduced in this chapter.

Modular design is adopted in hardware and software structures, and the corresponding modules will be described in detail. Every hardware module is a separate subsystem which is connected together by waterproof aviation plugs. An automatic pumping system is equipped in the USV to drain water when the water level in the hull exceeds the warning level. Similar to the hardware system, every software module is a separate processor that is connected together by shared memories. Since all processors share a single view of data, the communi‐ cation between processors can be fast as memory access. When the shared memories have been created, all the processors needed to do is to map the shared memory and initialize the read/ write lock of thread in shared memory struct.

### **2.1. Hardware design**

**1. Introduction**

28 Recent Advances in Robotic Systems

in the rescuing operations.

jointly [3].

Floods are among the most major climate-related disasters and have resulted in substantial losses including enormous property damage and human casualties [1]. Numbers of casualties and losses could be larger in the future in response to global warming. The biggest challenge lying in rescuing operations is the low efficiency and the high risk of the rescuers, which is also aproblemfocusedonbythiswork.Unmannedsystemisoneofthe solutions thatreplacepeople

Unmanned surface vehicles (USVs), also called autonomous surface vehicles (ASVs), are often used to name the vehicles, which can run on the surface autonomously. Surface robot-assisted flood disaster rescue and inspection is a new research direction in the field of robotics. Here are some obvious advantages: (1) the smaller size allows the USVs to access to narrow and small space to get detailed information; (2) remote operation can avoid casualties of the rescuers caused by the unexpected potential dangers. After Hurricane Wilma in 2005, USVs have been used for emergency response by detecting damage to seawalls and piers, locating submerged debris, and determining safe lanes for sea navigation [2]. After the Fukushima nuclear accident in 2011, the United States and Japan have used robots to assess the damage

Also, in 2007, a new Trimaran unmanned surface vehicle (TUSV) as a test-bed to verify the robust motion control strategies has been designed in Shenyang Institute of Automation, Chinese Academy of Sciences (SIA, CAS) [4]. After that, in 2012, a water-jet propulsion USV equipped with different kind of sensors and ground control system has been designed and implemented in SIA to improve the performance of USV [5]. In 2015, to increase the reliability and real time of USV, the software architecture has been designed based on a real-time operating system QNX 6.5.0. Also, the selection of an appropriate platform and associated hardware as well as useful and sufficient sensors, and integrating these two entities has been taken into consideration. Modular design is adopted in the hardware and software structures to improve system scalability. The hardware structure comprises six sub-systems, including the on-board control computer sub-system, power sub-system, communication sub-system, sensor and perception sub-system, ground station sub-system, and execution sub-system. The software structure comprises six modules, the communicator module, GPS-IMU module, protocol module, tracker module, controller module, execute module, and engine module. In general, the surface environment of flooding disasters, including fixed obstacles, floating obstacles, narrow canals, and the wind/wave/current disturbances, makes the target difficult to be inspected by an USV, because it presents a great limitation in trajectory tracking in complicated surroundings. The primary reason is the difficulty of obtaining accurate and applicable dynamical models. The hydrodynamic mechanism is very complex, and the dynamical model parameters change with Froude number *Fr* =*U* / *Lg*, where *U* is the operating speed of USV, *L* is the overall length of USV (the submerged length of USV), and *g* is the acceleration of gravity [6]. When the Froude number is <0.5, the main fluid forces exerted on USV are the hydrostatic pressure by replacing water with respect to hydrodynamic pressure, called *displacement area*; when the Froude number is >0.5 but <1, the main fluid forces

The USV system designed and implemented in SIA, CAS is shown in **Figure 1**. Its basic parameters are provided in **Table 1**.

**Figure 1.** The USV platform.


**Table 1.** Performance parameters of the USV.

The material of USV is fiber-reinforced polymer (FRP) which is a composite that is suitable for structures in corrosive environment and long-span lightweight structures due to its highstrength, light-weight, and anti-corrosive qualities [11].

To improve system scalability, the hardware structure adopts modular design. The hardware structure comprises six sub-systems, including the on-board control computer sub-system, power sub-system, communication sub-system, sensor and perception sub-system, ground station sub-system, and execution sub-system.

### *2.1.1. On-board control computer sub-system*

The on-board control computer sub-system (**Figure 2**) contains an Advantech computer UNO-2170 with 2X LAN, 4X COM, 1X 32G Compact Flash (CF), and 2X PCM-3780. The Advantech computer UNO-2170 supports QNX Neutrino Real-time Operating System (RTOS) and can be used to record the experimental data in 0.01 s. The PCM-3780 is a general purpose multiple channel counter/timer card for the PC/104 bus. It provides two 16-bit counter channels which can be used to produce the required Pulse Width Modulation (PWM) wave to control the ignition/flame switch servo, steering rudder servo, engine throttle servo, and the selector switch servo. Using the Advantech computer UNO-2170, the GPS-IMU data, and the command data from ground station sub-system can be received though two COM serial ports.

Design, Implementation and Modeling of Flooding Disaster-Oriented USV http://dx.doi.org/10.5772/64305 31

**Figure 2.** On-board control computer sub-system.

### *2.1.2. Power sub-system*

**Figure 1.** The USV platform.

30 Recent Advances in Robotic Systems

**Table 1.** Performance parameters of the USV.

strength, light-weight, and anti-corrosive qualities [11].

station sub-system, and execution sub-system.

*2.1.1. On-board control computer sub-system*

**Length Width Height Max velocity Payload** 2800 mm 700 mm 370 mm 36 km/h 70 kg

The material of USV is fiber-reinforced polymer (FRP) which is a composite that is suitable for structures in corrosive environment and long-span lightweight structures due to its high-

To improve system scalability, the hardware structure adopts modular design. The hardware structure comprises six sub-systems, including the on-board control computer sub-system, power sub-system, communication sub-system, sensor and perception sub-system, ground

The on-board control computer sub-system (**Figure 2**) contains an Advantech computer UNO-2170 with 2X LAN, 4X COM, 1X 32G Compact Flash (CF), and 2X PCM-3780. The Advantech computer UNO-2170 supports QNX Neutrino Real-time Operating System (RTOS) and can be used to record the experimental data in 0.01 s. The PCM-3780 is a general purpose multiple channel counter/timer card for the PC/104 bus. It provides two 16-bit counter channels which can be used to produce the required Pulse Width Modulation (PWM) wave to control the ignition/flame switch servo, steering rudder servo, engine throttle servo, and the selector switch servo. Using the Advantech computer UNO-2170, the GPS-IMU data, and the command

data from ground station sub-system can be received though two COM serial ports.

The whole on-board control computer sub-system, as well as all sensors, is powered by a 12 V battery jar. Besides, considering the possibility of overvoltage at the time of switching on power, Advantech PCM-3910 DC-DC power supply module is utilized to smooth the output voltage of the battery. Moreover, the engine can generate electricity to recharge the two batteries using a battery isolator to avoid the voltage dropping when the engine is starting. The working time of the USV system is larger than 2 h.

### *2.1.3. Communication sub-system*

The communication sub-system mainly contains a Futaba receiver, two FGR2 900 MHz industrial radios, a wireless router, and an image transmission equipment. The Futaba receiver is used to receive the signal from the Futaba remote controller in emergency case. The industrial radio in ground station sub-system is used to transform command data from ground station sub-system to on-board control sub-system, while the other industrial radio in on-board control computer sub-system is used to transform feedback data from on-board control computer sub-system to ground station sub-system. The maximum communication distance from ground station sub-system to on-board control sub-system is 20 km. The wireless router is used to connect debugging computer with UNO-2170 computer since it is not convenient to use QNX SDP on a QNX Neutrino RTOS system for self-hosted development. The image transmission equipment is used to transfer the video of the IP camera.

### *2.1.4. Sensor and perception sub-system*

The sensor sub-system contains a GPS-IMU system (see **Table 2**), an IP camera, a sonar, and a LIDAR. The GPS-IMU is used to locate the USV and obtain some inertial states such as attitude, velocity, and acceleration. The IP camera can monitor the environment of USV both in daytime and at night since it integrates infrared and visible light sensing device. Video from the IP camera is compressed based on the standard of H.264 and is transformed into the ground station sub-system through an image transmission equipment. The sonar and LIDAR sensors are also equipped in the USV system to detect the obstacles under and above the surface, respectively.


**Table 2.** Specification of GPS-INS (XW-GI5630).

### *2.1.5. Ground station sub-system*

Ground station sub-system (**Figure 3**) is an important human computer interaction platform for information processing.

**Figure 3.** Ground station sub-system.

It is the main controller unit of the USV system except for the on-board control computer subsystem and plays an important role in assisting the operator to monitor the USV's state realtime. When the USV is in some emergency situations, the operator can take appropriate disposition to ensure the safety of the USV through the state displayed on the ground station sub-system.

The ground station sub-system includes a high-speed computer, two screens (one is data screen, the other is video screen), communication device and two joysticks (control the rudder angle and engine throttle of the USV system, respectively). It allows remote controller operates the USV such as ignition/flame, speed, and course keeping.

### *2.1.6. Execution sub-system*

station sub-system through an image transmission equipment. The sonar and LIDAR sensors are also equipped in the USV system to detect the obstacles under and above the surface,

Ground station sub-system (**Figure 3**) is an important human computer interaction platform

It is the main controller unit of the USV system except for the on-board control computer subsystem and plays an important role in assisting the operator to monitor the USV's state realtime. When the USV is in some emergency situations, the operator can take appropriate disposition to ensure the safety of the USV through the state displayed on the ground station

respectively.

32 Recent Advances in Robotic Systems

**Specification Value**

Attitude accuracy 0.5° (1 σ)

Speed accuracy 0.1 m/s

Gyro zero offset ±100°/s

**Table 2.** Specification of GPS-INS (XW-GI5630).

*2.1.5. Ground station sub-system*

for information processing.

**Figure 3.** Ground station sub-system.

sub-system.

Heading accuracy 0.2° (1 σ, base line ≥ 2 m)

Data updating rate 1 Hz/5 Hz/10 Hz/100 Hz Gyro range ±100°/s (optional ± 300°/s)

Position accuracy 2 cm + 1 ppm (CEP)

The execution sub-system (**Figure 4**) contains four servos: a rudder servo (used to control the rudder angle of USV), a throttle servo (used to control the throttle size), an ignition/flame servo (used to start or stop the USV), and a switch servo (used to select the ground station or the remote controller to control the USV). The four servos receive the control data from the onboard control computer sub-system or remote controller and take corresponding actions.

**Figure 4.** Execution sub-system.
