Monorail Car_s Wireless Control System Based on Smartphone Platform---IEEE2011

7/31/2019 Monorail Car_s Wireless Control System Based on Smartphone Platform---IEEE2011

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Monorail Cars Wireless Control System based on Smartphone Platform

Xue Huixia, Gao Lin, Wang Lu, Li Wenbin, Yang Kai

School of Technology Beijing Forestry University, Beijing, 100083, China

[email protected], [email protected]

AbstractTo meet the mountainous districts situation in

China, this paper introduces a monorail car's wireless control

system used in orchard which is based on smart phone and

GPRS wireless communication technology. The system can

obtain monorail cars speed and position information by

rotary encoder, control and transmit data by wireless

communication. A SMS module on Windows Mobile

Embedded OS 6.1 is developed based on GSM protocol system.

Smart phone can receive cars initial information and send

orders to the on-vehicle controller for operating the car by

GSM message. It describes how the hardware platform works

and how to accomplish the design with software. Meanwhile, ittests the data transmission time and makes improvement. The

rational design makes it easier to operate, which is proved to

be available by tests.

Keywords-Smartphone; Monorail car; Windows Mobile;

GPRS communication; Wireless control

I. INTRODUCTIONFruit trees planting plays a decisive role in the economic

development in mountain areas, fruit picking andtransporting must been taken into account. Therefore,scholars from South Korea, Japan, Taipei, PRC and otherplaces do much research and develop monorail cars for

transporting fruits, whose track is easier to set up. It will notinterfere with the planting and growth of crops withoutenvironmental constraints. The monorail car can becontrolled by manual or automatic, and any reports aboutremote wireless control vehicles, and other aspects of vehiclereal-time capture important information have not yet beenseen [1-2].

With the continuous development of science andtechnology, the wireless mobile communication network hascovered our town and country. Cell phone is no longer aluxury, which has been very popular. If a mobile can controlthe monorail car wireless in time, it may not only reduce thelabor intensity, improve transport efficiency and automation,but also keep abreast of monorail car in the case of

unmanned operation, and easy to control remotely. Thispaper proposes a monorail car's wireless control system usedin orchard which based on smart phone and GPRS wirelesscommunication technology.

II. MONORAIL CAR REMOTE CONTROL SYSTEMARCHITECTURE

For the purpose of obtaining the monorail car's speed andposition information, transmitting data and controlling thecar by smart phone, the system consists of smart phone

platform, ARM core processor, GPRS communicationmodule and data acquisition module.

According to the system function, the hardware platformis divided into two parts: a remote controller and an on-vehicle controller. Smart phone with Windows MobileEmbedded OS is selected to for the remote controller, whichcan receive the monorail car's running information andcontrol it remotely. On-vehicle controller is mounted on themonorail car is a small ARM embedded system, which canmeasure the speed and position in time, detect the faultsautomatically, send and receive data wirelessly, and display

data, execute the control commands as well. It includesARM9 core chip, LCD, rotary encoder, impulse level switchand detection circuit, keypad, failure detection alarm circuit,control circuit, power supply circuit as well as the GPRSmodule. Taking vast mountainous areas and the mobilecommunication network spreading all over the country-towns and villages into account, SMS mode of GPRS(General Packet Radio Service) wireless communicationtechnology is adopted to meet the needs of fruit productionand be convenient to large-scale production management,which is a communication for distance wireless controlbetween smart phone and on-vehicle controller. The systemarchitecture is showed as figure 1.

Figure1. System architecture drawing

The system has such abilities as below: first, users willpress the "start" button on the phone control system interface,then the phone will send instructions to remote on-vehiclecontroller, when the message is received, the monorail car

starts and replies "Start OK" to phone. In the course of the

operation of monorail car, when users need obtain the statusof the monorail car, he can just press the "Status Inquiry"button, and then the system will send inquiry message to

GPRS

Monorail car

GPRS

MobileOrchard

2011 Third International Conference on Measuring Technology and Mechatronics Automation

978-0-7695-4296-6/11 $26.00 2011 IEEE

DOI 10.1109/ICMTMA.2011.444

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remote on-vehicle controller. When the inquiry message isreceived, information of speed and position is obtained andprocessed, after that these real-time data will be transferredto phone and displayed in time, so users can get what theywant. When users want to stop the car, he can press "stop",

same with the steps did above, it sends "Stop OK" to

phone as soon as the slave computer received information.

On-vehicle controller hardware block diagram of the systemis shown in Figure 2.

Figure 2. The block graph of on-vehicle controller hardware structure

III. SYSTEM HARDWARE DESIGNA. The Hardware design of Smartphone

SMS messages based on smart phone platform will besupported and restricted by smart phone software andhardware [3]. The system adopts Windows Mobile-basedsmart phone platform, used TI's OMAP850 (openingmultimedia applications platform) chip, which belongs to thetype "application processor + digital part of the baseband".OMAP processors have a dual-core (DSP and ARM)structure with strong computing power, low power and richperipheral interfaces typically. Table 1 shows Mobilehardware parameters.

Table 1. The mobile hardware parameters

Category Parameters

CPU OMAP850

Frequency 201MHZ

Data bus 16-bit

Support band GSM 850/900/1800/1900MHz

Data transmission GPRS

Screen Material TFT

Screen Color 65536 colors

The main screen size 2.8 inches

The main screen parameters 240 320 pixels

Screen Type Touch Screen

Memory 128MB

B. GPRS Communication ModuleGPRS (General Packet Radio Service) communication

technology is developed from GSM system and is usedwidely. Typical applications include: industrial control,environmental protection, road traffic, mobile office, retail

services, and public security systems. GPRS allows users totransmit data from terminal to terminal without using thecircuit-switched model, and is fitted for a sudden, frequent,small amount of data transmission of data mode.

In the system, the communication module is the key partof smart mobile phone and on-vehicle controller's datatransmission, selected the CENTEL's PIML-900/1800 type

GPRS module which including a GSM/DCS dual-bandmode, integrated RF and a GSM radio base band processingcircuit. It can provide users with a full-featured systeminterface. PIML-900/1800 is a GSM module including the900/1800 dual-band GPRS, support GSM900/DCS1800dual-band; circuit-switched data transmission (up to 9,600bit/s); Short Message Service; power interface; serial portand the SIM card interfaces. The module can insert anexternal SIM card. ARM9 core chip connects with thePIML-900/1800 through the asynchronous serialcommunication interface. And it sends AT commands tocontrol GPRS module and transmit data.

C.Monorail cars Positioning and Speed MeasurementModuleAccording to character of our country's mountainous

fruits production, this paper proposes the traditionalincremental rotary encoder to complete the monorail car'sposition and velocity-measuring used for delivery of fruits,the main feature is low cost and easy to implement, with ahigh measurement accuracy and anti-jamming capability.

Rotary encoder can convert the mechanical displacementof output shaft to pulse or digital quantity throughphotoelectric convention. Incremental encoder ischaracterized by its simple structure, price cheap and longmechanical life and so on [4]. Here, we use incrementalencoders belong to HMR-10G series, its response frequencycan reach 100KHz, 1024 pulses/rotation, and the voltage is

10V-30V. The rotary encoder has two-way pulse outputsignals calls A and B. There is a 90 phase gap between

pulse A and B. When rotary encoder rotates clockwise,

channel A's output waveform is 90 ahead of that of

channel B; when rotates counter-clockwise the consequenceis just the opposite. Firstly, install the rotary encoder on thewheel of monorail car. Secondly, since the optical coded discof rotary encoder and the car's wheel is coaxial, as theoptical coded disc is rotating at the same speed with the car.Then a number of pulse signals can be output the rotaryencoder's internal inspection devices. Finally, the car'sposition, speed and steering can be calculated by thesepulses and the car's initial parameters.

IV. SYSTEM SOFTWARE IMPLEMENTATIONA. Smartphone platform

Windows Mobile is used as a software platform forPocket PC and Smart Phone by Microsoft. The applicationof the Windows OS, used in personal device, is the mobileWindows version released by Microsoft in handheld devicefield. At present, Windows Mobile OS are mainly used inPPC mobile phone, PDA, MP3 etc. The OS has three species:

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Windows Mobile StandardWindows Mobile Professional,

Windows Mobile Classic. The commonly used version isWindows Mobile 6.1, and this design is adopting WindowsMobile 6.1, for the OS familiar with the Windows OS usedin PC, the steps in developing software is the same with thatin PC. Visual Studio 2005 is adopted, .NET Framework andWindows Mobile SDK are integrated into this platform, and

the basic functions of Windows Mobile are very easy toexecute a call. Meanwhile, the software realizes to receive,transfer, process and display message as specified, friendlyinterface and easy to use.

The smart phone mainly sends instructions to lowercomputer, identify corresponding data flow when receivedmessage from lower computer, display on screen afterprocessing. The software interface has three control buttonsand two auxiliary buttons. The two auxiliary buttons areused to add buddy list, the buddy you added are saved in thedropdown list of "send to" dialog box.The auxiliary "sendto" button on the right side is a shortcut key, it has threesecond-level menus inside: 1. Switch On; 2. Switch Off; 3.Status Inquiry. The function of second-level menu is the

same with that of buttons; it is convenient for different users.The software interface of smart phone platform, the

picture of experimental procedure and the software flowchart are showed in Figure 3, 4 and Figure5.

Figure 3. Diagram of Mobile software interface

Figure 4. Picture of smart phone platform

Begin

(Open the software)

PressAdd contacts button

load cars phone number

PressStart button, send

command to on-vehicle controller

Receive and show the feedback

message from on-vehicle controller

End

PressInquire button, send

inquire command to on-vehicle

controller

Receive the feedback message and

show cars real time information

PressStopbutton, send stop

command to on-vehicle controller

Receive and show the feedback

message from on-vehicle controller

Start up the monorail car?

Does it need to know cars

running information?

Stop the monorail car?

Y

N

Y

Y

N

N

Figure 5. Flow chart of mobile software

B. The SMS message Mode and Communication ProcedureThere are three Receiving & sending SMS message

modes: block mode text mode and PDU mode. Drive

support is necessary when use block mode, so now it isseldom used. Text mode are pure text method mode,different character sets can be used, so it is very easy. PDUmode is the mainstream message coding mode, the messagetext is 8bit, it is delivered after transfer to hexadecimal data[5]. Because Chinese are not included in the instruction andit is must be short enough, the relatively simple text mode isadopted.

Sending SMS message uses AT instruction set, GSM ATinstruction set is formulated by EuropeanTelecommunications Standards Institute (ETSI), it is a ruleused for mobile phone and mobile device. Then sendingshort message through proper device can uses such set [6].Here are some common AT commands for sending andreceiving SMS messages [7].

(1) The process of sending short messageStep 1, Send AT+CMGF=1, set the mode of the module

for text mode;

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Step2, When returned OK, send AT+CMGS=13XXXXXXXXX(your mobile phone number), press Enter.

Step 3, Input the message information behind the ">",press "Ctrl+Z" to send message (Note: GPRS module doesnot support the Chinese, it can only send ASCII codecharacters). If sent successfully, the module returns"+CMGS:OK"; otherwise, the module returns ERROR.

(2) Receive short messageStep 1, Send AT+CMGF=1, set the mode of the module

for text mode;Step 2, When returned OK, send AT+CMGR=index,

which the message you want to read in the store, serialnumber is the index, press Enter.

Step 3, Show the current storage area in the selectedSMS.

(3) Delete short messageSend AT+CMGD = index, press Enter, when it returns

OK, that shows remove accomplishment.

C. Wireless Data Transmission time testIt is very important to grasp the Operating Information

and security information when using GPRS wirelesscommunication technique to acquire monorail car's positionand speed information. It will do some research in real-timewireless data transport in this design.

Every kind of communication link has delay includedGPRS, it will affect wireless data acquisition real-timing.The factors are below: transport speed of communicationlink, the environment, amount of data transported every time,voice service is busy or not and net traffic load, data terminaldevice and so on. On-vehicle controller and groundcontroller are constituted with ARM9 processor, in thecourse of data transport, converting, calculation, processingalso needing some time, these are factors influence delay.

The transmission delay test is carried out at Beijing

Phoenix Ridge Mountain Orchard. Test includes: groundcontroller sends data, on-vehicle controller receives data; on-vehicle sends data, ground controller receives data, theconsequences are showed in table 2.

TABLE 2 Transmission time testing at Beijing Phoenix Ridge Mountain

Orchard (Date: 4.20.2010 Time: 10:00-11:00)

Testing

times

Delay time

(Unit: s)

Testing

times

Delay time

(Unit: s)

Testing

times

Delay time

(Unit: s)

1 6.93 8 6.54 15 6.59

2 6.77 9 6.98 16 6.66

3 6.88 10 7.26 17 6.83

4 6.55 11 6.62 18 6.68

5 6.67 12 6.60 19 6.85

6 6.22 13 7.13 20 6.897 6.13 14 6.26 21 7.14

On the table, the average delay is 6.73 seconds, obviouscommunication link, environment and different data affecttransporting time. At different time, even transport the samedata in the same place, delays are a little different.

Aiming at the problem of data transmission delay withGPRS wireless technology, some methods can be used toimprove the program, such as, check interference source

around, minimize exterior influence, choose high processingspeed ARM9 processor, minimize time that used forprocessing data; simplify code, cut down executing time andso on. But transmit speed of communication link, theenvironment, amount of data transmission every time, voiceservice busy or not and net traffic load are determined bytelecommunication system which we can't change. So in the

design, several seconds delay is unavoidable.The fastest speed of car is 40 meters per minute, after

many tests, it is revealed that the average GPRS delay is 6 to7 seconds. Time compensation is added in the code, this willeliminate the influence of delay to car's position and speedreal-timing.

V. CONCLUSIONSThis paper introduces a monorail car's wireless control

system used in orchard which is based on smart phone andGPRS wireless communication technology. Through thesystem hardware and software debugging, laboratoryoperation, the design can complete the monorail car speedand position's real-time measurement and data transmission

between mobile and on-vehicle controller.Although a short delay happens in GPRS remote wireless

communication technology in the system, in combination ofthe monorail car's actual speed and improvement proposals,the impact of real-time extension can be neglected. Thesoftware interface of transporting fruit monorail car's remotecontrol system is designed to be simple and friendly, besuitable for all kinds of users. The system has a wide rangeof applications and a great application prospect, it is of greatsignificance to reduce labor intensity and achieve automaticdriverless monorail vehicles in China.

ACKNOWLEDGMENT

This project is supported by the National SpecialResearch Programs for Non-Profit Trades (Forestry) (GrantNo.200804029).

REFERENCES

[1] Zhan tingwen, Zhang xuefeng, Liu changle, Zhao shaosong, Liu yu.Application Status of Monorail Vehichles, Forestry Machinery andWoodworking Equipment, 2008,36(12):45-47 (in Chinese)

[2] http://www.china.com.cn/news/txt/2008-12/18/content_16968679.htm

[3] Yang zihua, Hu qian, Ling jiangrong, Design and Implementation ofSMS System Based on Smartphone Platform, CommunicationsTechnology, 2007, 40(9):70-72. (in Chinese)

[4] Wang jianfei, Hu shuju, Li jianlin, E chunliang, Control of a PMSGBased on Incremental Encoder in Direct-Drive Wind Power System,Electronic Technique,2008, 11:8-11.(in Chinese)

[5] Yi qing, Shi zhiguo, Wang zhiliang, Li qing, Information QuerySystem Based on GSM Short Message, Computer ApplicationResearch, 2003,(2):63-65.(in Chinese)

[6] Jiang ping, Chen hongji, Design of remote wireless measurementand control system based on GSM, Information Technology,2008,(10):62-67.(in Chinese)

[7] Huixia Xue, Lin Gao, Wenbin Li, Jun Liu, Junmei Zhang, Liu Yang,ARM9-based Real-time Acquisition of Orchard Soil Information and

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Monorail Car_s Wireless Control System Based on Smartphone Platform---IEEE2011