The Design of Smart Rescue Robot Based on the ARM Remote Control

Abstract. CPU uses STM32F103RBT6 as core， human thermal infrared sensors， ultrasonic sensors and temperature sensors as detection systems， motion control module as the power system， real-time monitoring and control system， wireless data communication system and wireless audio and video transmission system as robot's "ears" and "eyes"， so that a robot is capable of all-round， three-dimensional "feel" the environment， and make accurate judgments and control artificially.

Key words： wireless communications； wireless audio and video transmission； human thermal infrared sensor； ultrasonic sensor； temperature sensor

1 Introduction

In recent years， earthquakes and other natural disasters occur frequently， causing huge economic losses. Post-disaster relief work has been attracting the most attention， but facing the complexity of the post-disaster environment， rescue workers cannot enter some places， and cannot make a judgment of the complex state inside and whether there are people trapped. In this case， water， food and other relief supplies will not be served. Based on these two points， we research and design a smart remote rescue robot， which reached the expected experimental results through tested.

2 The Overall Design of an Intelligent Rescue Robot

The integrated design employs ARM development board as the major hardware， external ultrasonic sensors， temperature sensors， the human thermal infrared sensor， motion control modules， wireless communication module and wireless audio and video transmission module as the hardware circuit to make the robot detect changes in the environment and the existence of life in walking process. The motor of movement and control module employ the torque 280 motor inductance and the chip is L298N dual H-bridge driver chip， with a direct drive to 3-30V DC motor and load of 7.5KG. Wireless audio and video transmission module enable PC receiving control terminal to monitor its surrounding environment， and thus control the direction and route of the robot's "walking". Wireless communication module is an important part of the data communication transmission module of the robot， as the detected information all around the robot needs to be transmitted through it. PC software in the entire process of controlling a robot played a full surveillance role， as it has to control the route， receive a video screen， and also display the surrounding environment information and increase the robot's judgment ability. The overall system design diagram is shown in Figure 1.

3 System Hardware Design

3.1 Ultrasonic Sensors

The two most important ends of the ultrasonic sensor are Trig end and Echo end. Its working principle is that when the Trig end inputs high level above 10US， the system will send eight 40KHzultrasonic pulses， and then detect the echo signal. After detecting the echo signal， the module also needs to measure temperature value and correct it in accordance with the current temperature ranging results. Then it will output the result after the correction by the Echo end. Now the measured distance value is converted to 340m / s， the time value of 2 times， and by Echo terminal outputs a high level， to calculate the distance value of the duration of this high level. The resulting distance formula is：

Measured distance = （the high level duration * 340m / s） / 2

Ultrasonic sensor startup code as follows：

GPIOA-> ODR | = 1

Delay us （20）； / / ultrasonic Trig foot sustained output 10US more than higher level issue ultrasound to detect the distance

The GPIOA-> ODR & = （1

Interrupt service routine code is as follows：

Void EXTI15_10_IRQHandler （void）

{

If （start timer == 0）

{

TIM4-> CR1 | = 0x01； / / enable counter

Start timer = 1；

}

Else if （start timer == 1）

{

Start _timer = 0；

Time = TIM4-> CNT； / / save count value

TIM4-> CNT = 0x0000； / / empty the counter

Distance = time * 17/10； / / unit conversion

Print （"% d cm from the front of the ＼ r ＼ n"， distance）；

}

EXTI-> PR = 1

}

3.2 Human Thermal Infrared Sensor

When a person enters the sensing range， the OUT output ports of human thermal infrared sensor will output high level， and when people leave the sensor range， it will automatically delay off it and output low level at the same time. It represents repeatable trigger. That means when the sensing output high level， if someone appears in an induction range， it will sustainably output high level and the high level will become law after people leave. Its detecting the person's appearance will automatically postpone after a delay time period， and will regard the time of people last occurrence as the starting point for the delay time， ensuring that the detection's continuity. The human thermal infrared sensor is shown in Figure 3.

3.3 Temperature Sensor

The temperature sensor has three ports， namely power， ground and data ports. Before the measurement， imbed the corresponding date of -55 ℃ into the subtraction counter and the temperature registers， and the subtraction counter count the pulse signal generated in the subtraction counter. When the preset value of the subtraction counter is reduced to 0， the value of the temperature register will add one and the subtraction counter preset will be re-loaded. Then the subtracted counter is re-started the low temperature coefficient of the crystal oscillator generated pulse signal count. And in this way， until another internal subtraction counter counts down to 0， it will stop the temperature register value and the temperature measures the temperature register at this time. The main program code is as follows：

Short DS18B20_Get_Temp （void）

{

u8 temp ；/ / temporary variables

u8 TL， TH；

Short tem；

DS18B20_Start （）； / / start temperature conversion

DS18B20_Rst （）；

DS18B20_Check （）； / / Check if there is the presence of the DS18B20

DS18B20_Write_Byte （0xcc）； / / write a byte to DS18B20

DS18B20_Write_Byte （0xbe）； / / conversion

TL = DS18B20_Read_Byte （）； / / read low eight

TH = DS18B20_Read_Byte （）； / / read high eight

If （TH> 7）

{

TH = ～ TH；

TL = ～ TL；

Temp = 0； / / temperature is negative

}

Else

Temp = 1； / / temperature is positive

Tem = TH； / / for high eight

Tem

Tem + = TL； / / low eight

Tem = （float） tem * 0.625； / / temperature conversion

If （temp） return tem； / / return temperature value

Else return-tem；

}

3.4 Movements and Control Module

Movement and motor control module not only has a characteristic of low-noise， dynamic performance and high stability， but also can circle in 360 °， with a particularly flexible turning driver module， using ST L298N dual H-bridge driver chip. It can directly drive two Road， 3-30V DC motor， increase the speed of the robot to 30cm / s， with a ramp angle of 30 ° or more， and to support 3.3VMCU control and PWM speed control， so you can easily control the size and direction of the DC motor speed.

Part of the program code as follows：

While （1）

{

If （USART_RX_STA & 0x80）

{

len = USART_RX_STA &0x3f；

Command = USART_RX_BUF [0]；

Switch （command）

{

Case 'a'： / / forward command

LED0_PWM_VAL1 = save speed； / / save the left side of the forward speed of the track

LED0_PWM_VAL2 = 0；

LED0_PWM_VAL3 = save speed； / / Save the forward speed of the right side of the track

LED0_PWM_VAL4 = 0；

Print （"forward ＼ r ＼ n"）；

Break；

...........

}

}

}

3.5 Wireless Communication Module

Wireless communication module adopts APC220-43 wireless data transmission module and uses transparent data transmission as its external interfaces， with a transparent transmission of data of any size. Inside it has set a buffer zone with a large capacity of site 256 bytes， which can transfer 256bytes data at one time. It is embedded within a high-speed single-chip and high-performance RF chip， adopts efficient circulation intertwined correction error detection code， which can rectify continuous burst errors of 24bits with a coding gain of nearly 3dBm. It can automatically filter out errors and false information， realizing a transparent connection. APC220-43 wireless communication module is shown in Figure 4.

3.6 Wireless Audio and Video Transmission Module

Wireless audio and video transmission module includes USB audio and video capture card， wireless audio and video signal transmission module and the detection camera. The USB audio-video acquisition card and the wireless receiver modules are connected together as a wireless audio and video image receiving end while the detection camera and wireless transmitter module are connected together as the emitting end of the wireless audio and video images. The video image is transmitted through the wireless transmitter module and the wireless receiver module.

4 System Software Design

PC control receiving end mainly includes four parts： video operating area， feedback area， and robot-controlled areas and data transmission area. A PC controls the receiving end is shown in Figure 5.

4.1 Video Operating Area

Video operating area includes the bottom of "Start"， "Video Source"， "Video Format" and "Save Image". Through tests， if we chose 640 * 480 resolutions in the entire video settings， we will get a better video image of pixel depth of YUYZ format.

4.2 Feedback Area

Its main function is to receive the detected current surrounding environmental information， including the current ambient temperature， the distance from the obstacle， and the existence of humans， etc.. It has the automatic update function of probing information， with real-time feedback to the current observation information.

4.3 Robot Control Area

The main control buttons include "forward"， "backward"， "left"， "right turn"， "acceleration"， "slow down"， "stop"， "acceleration" and "deceleration" and so on. Inside， the "acceleration" and "deceleration" buttons have twice acceleration and deceleration function. We can control the direction and speed of the robot forward through these buttons.

4.4 Data Transmission Area

You can either manually input the command as the control button or send some other command as a spare "send button".

Summary：

The design is based on the ARM development， integrating life detection， wireless audio and video transmission， wireless communications and data transmission， comprehensively using various sensors. Through the experimental test by simulating the rescue site， it can complete the exploration and rescue operation in a more complex surrounding environment. It also is capable of carrying small amount of food and water delivered to the trapped personnel， successfully completing the detection of a rescue mission.

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