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# Design of Expert System for Fault Diagnosis of Water Quality Monitoring Devices

Qiucheng Li, Daoliang Li, Zhenbo Li

► To cite this version:

Qiucheng Li, Daoliang Li, Zhenbo Li. Design of Expert System for Fault Diagnosis of Water Quality Monitoring Devices. 5th Computer and Computing Technologies in Agriculture (CCTA), Oct 2011, Beijing, China. pp.524-529, 10.1007/978-3-642-27281-3_59. hal-01351858

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Submitted on 4 Aug 2016

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# Design of expert system for fault diagnosis of water quality monitoring devices

Qiucheng Li¹, Daoliang Li¹,*, Zhenbo Li¹,

1 College of Information and Electrical Engineering, China Agricultural University, Beijing, 100083, P.R.China

* Corresponding author; E-mail: dliangl@qq.com

**Abstract.** A new system for automatic detect fault of water quality monitoring devices used in aquaculture is proposed in this paper. The proposed system can detect the whole system which includes platform、gateway、WSN、sensor、actuator. China is the world's largest freshwater culture nation which provides 80% of the freshwater culture fish. The water quality is essential to freshwater culture, and the environment is controllable. In this paper, water quality sensors are used to detect the water quality of culture ponds. By the use of wireless sensor networks, the data can be sent to remote server. So farmers can check the state of the culture ponds where the internet is available. This paper is proposed to detect the state of the monitoring system, if the monitoring system falls, the system will alarm to the user.

**Keywords:** Automatic, On-line, Fault diagnosis, Aquaculture, Water quality monitoring

## 1 Introduction

China is the world's largest freshwater culture nation which provides 80% of the freshwater culture fish. The water quality is essential to freshwater culture, and the environment is controllable. In this paper, water quality sensors are used to detect the water quality of culture ponds. By the use of wireless sensor networks, the data can be sent to remote server. So farmers can check the state of the culture ponds where internet is available. Water quality is very important in aquaculture. We use WSN technology to monitoring the water quality to ensure the circumstance is suitable for the fish to grow. In this way, human has been released from hard working. The water quality monitoring system is essential for the aquaculture. If the monitoring system fails, and the water quality become bad, a lot of fish will die, farmer will lost a lot. So a new system for automatic detect fault of water quality monitoring devices used in aquaculture is proposed in this paper [1].
## 2 Water quality monitoring model

The water quality monitoring system proposed in this paper is used in outdoor aquaculture. The most important attributes of the water quality are dissolved oxygen and water temperature. If the dissolved oxygen is lower than 3mg/l, the growing of fish will be constrained. If the dissolved oxygen is lower than 1mg/l, the fish will die. Both the water temperature is too high or too low will constrain the growing of fish. The water quality monitoring model is illustrated by Figure 1. The first part is sensor which can detect both dissolved oxygen and water temperature. The second part is a transformer which is powered by solar battery and sends out the data collected by sensors wirelessly according to H 15.4 communication protocol. The third part is gateway which receives the data send from transformer and sends them out to the remote server.

<figure><img src="image_3.png" /><figcaption>Fig. 1. Water quality monitoring model</figcaption></figure>

In this system, the sensor has three channels, includes dissolved oxygen, water temperature, and dissolved oxygen engineering value. The transformer has three channels, include device information, device voltage, and signal strength[2]. The gateway has seven channels, includes city power supply, current one, current two, switch signal, analog signal one, analog signal two, and device voltage. That information is the source of the fault diagnosis system [3].

## 3 Design of fault information database table

After three months observation of the current water quality monitoring system, fault object can be divided into five categories: software platform, gateway, transformer, sensor, and actuator. Fault grade can be divided into three categories: mild, moderate, serious[4]. Mild means that operation and maintenance staffs should know that. Moderate means that if operation and maintenance staffs have time, they should deal with the problem. Serious means that the fault is fatal, operation and maintenance staffs should deal with the problem as soon as possible. The fault information database table is illustrated by Figure 2. The fault diagnosis system stores the fault occurring time, and records fault reason and deal method which is added by operation
and maintenance staffs. In this way, if the same kind of fault occurs again, we can check the database to check the previous records [5].

<table><caption>Fig. 2. Fault information table (smart device)</caption><thead><tr><td>Field meaning</td><td>Field name</td><td>Data type</td></tr></thead><tbody><tr><td>ID</td><td>def_id</td><td>varchar</td></tr><tr><td>Smart device ID</td><td>dev_id</td><td>varchar</td></tr><tr><td>Fault type</td><td>def_type</td><td>int</td></tr><tr><td>Fault grade</td><td>defGrade</td><td>int</td></tr><tr><td>Fault occur reason</td><td>defOccurReason</td><td>Varchar</td></tr><tr><td>Fault occur time</td><td>defOccurTime</td><td>Datetime</td></tr><tr><td>Fault solved time</td><td>defDealTime</td><td>Datetime</td></tr><tr><td>Deal method</td><td>defDealMethod</td><td>Varchar</td></tr><tr><td>Channel ID</td><td>ch_id</td><td>Varchar</td></tr><tr><td>Fault description</td><td>def_desc</td><td>Varchar</td></tr></tbody></table>

## 4 Design of fault diagnosis rule database

The fault diagnosis rule database is illustrated by Figure 3. Rules is made on the base of careful observation of the water quality monitoring system. Each fault object has the expert to give the suggestion of the rule-making. Each fault object has four attributes, communication state, device state, data continuation state, data rationality[6]. Fault level has been divided into three levels. Serious means that the fault is fatal to the operation of the water quality system. Moderate means that the fault is not fatal to the operation of the water quality monitoring system, but the fault will be fatal to the operation of the water quality monitoring system. Mild means that the fault is not fatal to the operation of the water quality monitoring system, but the fault has the possibility to be fatal to the operation of the water quality monitoring system[7].

<table><thead><tr><td>Fault object</td><td>Fault level</td><td>Rule</td></tr></thead><tbody><tr><td>Software platform</td><td>serious</td><td>Receive no data in 10 minutes;</td></tr><tr><td>Software platform</td><td>serious</td><td>Illegal register;</td></tr><tr><td>Software platform</td><td>serious</td><td>The number of channels is not in compare with the platform;</td></tr><tr><td>Software platform</td><td>mild</td><td>Software platform time and reporting time asynchronous;</td></tr><tr><td>Gateway</td><td>mild</td><td>The reporting time subtract acquisition time is larger than 30 minutes;</td></tr><tr><td>Gateway</td><td>mild</td><td>The interval between two heart beats is larger than 2 times of cycle</td></tr><tr><td>Gateway</td><td>serious</td><td>The acquisition time is the same with the last data</td></tr><tr><td>Gateway</td><td>mild</td><td>The gateway voltage is lower than 4.4 volt</td></tr><tr><td>Gateway</td><td>mild</td><td>The reset number of gateway increased</td></tr><tr><td>Transformer</td><td>serious</td><td>The transformer voltage is the same with the last data</td></tr><tr><td>Transformer</td><td>mild</td><td>The transformer voltage is lower than 3.6 volt</td></tr><tr><td>Transformer</td><td>mild</td><td>The reset number of transformer increased</td></tr><tr><td>Sensor</td><td>serious</td><td>The sensor data is the same with the last data</td></tr><tr><td>Sensor</td><td>serious</td><td>The value is out of the upper limit and lower limit</td></tr><tr><td>Sensor</td><td>serious</td><td>The change rate is larger than 0.1</td></tr><tr><td>Actuator</td><td>mild</td><td>Illegal operation</td></tr></tbody></table>
**Fig. 3.** Fault diagnosis rule database

**5 Design of fault diagnosis flow chart**

I The water quality monitoring system is level clearly demarcated. If the gateway fails, the platform can't get the information below the gateway [8]. In the same way, if the transformer fails, the platform can't get the information below the transformer. The fault diagnosis flow chart is illustrated by Figure 4. The expert system of fault diagnosis for water quality monitoring system follows the flow chart illustrated by Figure 4.
<figure><img src="image_4.png" /><figcaption>Fig. 4. Flowchart for the identification of deficiency symptoms</figcaption></figure>
# 6 System interface

Fault information management is illustrated by Figure 5. The result of fault diagnosis is stored in the database. For the purpose of being friendly to the users, a web-based system interface has been developed. Users can search the device Id, fault level, fault type, fault state, fault occurring time[9].

<figure><img src="image_5.png" /><figcaption>Fig. 5. Fault information management</figcaption></figure>

Fault report is illustrated by Figure 6. The report can statistic the fault information. From this report, we can see the amount of each kind of fault happened in a specified period.

<figure><img src="image_6.png" /><figcaption>Fig. 6. Fault report</figcaption></figure>
# 7 Conclusion

In this paper, we presented an expert system for fault diagnosis of water quality monitoring devices based on rule database. The system allows a user to track the detailed information of the whole monitoring system. The architecture of the system has been described from several points of view and it has shown to have the ability to meet the requirements imposed on early warming of the water quality and monitoring devices and fault diagnosis of the monitoring system

In the architecture described above, each fault of the water quality monitoring system can be tracked for detailed information. Therefore, the system's stability can be enhanced. The profit of the aquaculture farmers can be ensured. For this reason, our future work will cover the study of artificial intelligence to make the system smarter[10].

# References

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