Ugv Rov Based On Wifi Standard Computer Science Essay

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Robotics and IT are at the cutting edge of the current technological revolution and globalization, augmenting human capabilities in different roles and environments, constantly pushing the possibilities of technology beyond human imagination. Autonomous and robotic systems solutions thus hold great potential, finding feet in areas such as remote sensing, military, telemetry, centralized command centres, search and rescue (extreme environments), and countless others.

The purpose of this project is to design and build a Wi-Fi controlled unmanned ground vehicle able to operate in normal environmental conditions. This is a basic scalable model, which can be further developed and modified for certain, platform specific tasks. Also the knowledge gained can be used to integrate and design other autonomous or remotely operated systems.

Using the above description, the scope of our project is to build an autonomous

surveillance system that can be remotely operated, providing video feedback of the

environment. Based on these principles we have managed to detail the design

specifications of the project. The UGV is a 1:10 RC car which can be controlled via Wi-

Fi from a remote client module from anywhere around the world. The remote client

module is built on C# Visual Studio. The server module integrated, is an embedded Wi-

Fi module (Lantronix Wiport B/G) mounted on the vehicle itself. We have also brought

additional features like obstacle detection and speech recognition facility into the foray

to ramp up the project.

Features and component designs are finalized using a stringent design methodology and the design process is done in an iterative manner i.e. if any component or feature is found to be unfeasible, design and tests are re-run.

For its design and construction the UGV is divided into six classes: Drive and Steer system, client module, server module, object detection, camera module, power transmission and supply system. For successful integration of all modules several complex calculations are done.

It should also be noted that this project does not aim to create something new (beyond the scope of this degree), but rather to integrate different technologies to provide new solutions and innovate, thus empowering ourselves and the society as a whole.

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Table of contents

1 INTRODUCTION ... .. 1

1.1 SCOPE OF WORK AND OBJECTIVES: ... ... 2

2 LITRATURE REVIEW: ... . 5

2.1 COMMUNICATION PATHS AND RANGE: ... .. 6

PRODUCTS COMPARISON AND UGV (WIFI-BOT) DESIGN VISION ... ... 8

3 REQUIREMENTS SPECIFICATION... ... 10

3.1 NON-FUNCTIONAL REQUIREMENTS ... . 11

3.1.1 Product requirements ... .. 11

3.1.2 Organisational requirements ... ... 11

3.1.3 External requirements ... . 11

3.2 FUNCTIONAL REQUIREMENTS... . 12

3.2.1 Category 1 ... . 12

3.2.2 Category 2 ... . 12

3.2.3 Category 3 ... . 12

4 PROJECT DESIGN ... .. 13

4.1 METHODOLOGY ... . 13

4.2 ARCHITECTURE OVERVIEW ... . 14

4.3 UGV(WIFI-BOT) SYSTEM ARCHITECTURE(MACRO): ... ... 14

4.4 UGV(WIFIBOT) SYSTEMS DETAILED ARCHITECTURE(MICRO):... . 15

4.5 COMMUNICATION PROTOCOL: ... ... 16

4.6 DETAIL MODULE DESCRIPTION: ... ... 16

4.6.1 Module 1 ... . 16

4.6.2 Module 2 ... . 19

4.6.3 Module 3 ... . 21

4.6.4 Module 4 ... . 23

4.6.5 Module 5 ... . 25

4.6.6 Module 5 ... . 28

4.6.7 Module 6 ... . 29

4.6.8 Module 7 ... . 30

5 IMPLEMENTATION ... ... 32

5.1 DEVELOPMENT STAGES ... . 32

5.1.1 Obtaining the Chassis: ... 32

5.1.2 The Client Application . 32

5.1.3 Voice Recognition Module: .. 35

5.1.4 Building the Speed and Steering Circuit: .. 40

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5.1.5 The Microcontroller Module: .. 42

5.1.6 The Objection Detection Module: . 46

5.1.7 The Follow Function: .. 50

5.1.8 Testing the Bot in Serial Configuration:... . 51

5.1.9 The Wireless Module: ... .. 51

5.1.10 Testing the Wi-port... .. 52

5.1.11 Network to serial problems: ... ... 53

5.2 KEY COMPONENTS ... .. 54

5.2.1 Lantronix Wi-Port: ... 54

5.2.2 Client Application Module: .. 54

5.3 RC CAR AND MICROCONTROLLER: ... .. 55

5.3.1 IR sensor and Camera: ... 55

5.4 USER INTERFACE ... .. 55

PAGE LEFT INTENTIONALLY BLANK ... .. 56

6 EVALUATION ... ... 57

6.1 UNIT TESTING... . 57

6.2 FUNCTION TESTING ... . 58

6.2.1 Testing Requirements. .. .. 58

6.3 RESULTS ... ... 58

7.2 CONCLUSIONS & FUTURE WORK ... . 61

REFERENCES ... .. 63

APPENDIX A: C# SOURCE CODE ... ... 64

APPENDIX B: HARDWARE SCHEMATICS ... . 79

APPENDIX C: LIST OF COMPONENTS ... .. 80

APPENDIX D: PROJECT TIMELINE ... . 81

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List of Tables:

Table 4.6.2.1 Comparison between Different Wi-Fi Modules----------------------------------------21

Table 4.6.3.1 Pic 16F877a Specifications---------------------------------------------------------------23

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Introduction

With the recent advances in Micro Electro Mechanical System (MEMS) technology, low cost and low power consumption wireless micro sensor nodes have been available [1][2][3]. In a wireless sensor network (WSN) there is a base station and many sensor nodes being randomly deployed. The sensor nodes monitor environmental factors such as temperature, air pressure, and motion, and send the sensing data to the base station. The base station acts as a gateway to deliver information from the sensor nodes to outside users who need it. In WSN, it is too difficult to initialize the sensor nodes and manage the sensor networks due to the large number of sensor nodes, which may number tens of thousands. Therefore, self-configuring sensor nodes are desirable in WSN. Moreover, in order to save energy, sensor nodes carry out data aggregation and compression before sending data to the base station, and execute energy efficient routing [4].

The sensor nodes in a WSN sense data and send it to the base station which delivers the information to the end users. There are lot of issues related to the transfer of information from sensor nodes to the base station which include issues related to Quality of service, issues related to congestion in the network and issues related to the lifetime of the WSN network. In our project we have studied the issues related to the network lifetime of WSN. In order to increase the lifetime of WSN the energy of the sensor nodes should be used efficiently.

The information from each sensor node can be sent to the base station either individually by each sensor node or it can be sent in the bulk form. Usually the sensor nodes which are being deployed had a limited amount of energy storage. So, if distance of base station will be far from the sensor node more energy will be consumed. Hence, the network will not last longer. The energy efficiency is the most important factor to prolong network lifetime of sensor nodes and balance energy consumption. There had been proposed different energy efficient routing protocols for Wireless Sensor networks. In our project we had a clear literature review of different energy efficient schemes and then we had developed our own energy-efficient routing scheme and had compared it with one of the renowned energy-efficient schemes. All the energy efficient schemes which we have studied proposed cluster based routing in which the amount of data to be transmitted can be reduced by dividing the network into small clusters, a cluster head being responsible for aggregating and relaying to t he sink the information gathered from the sensors of its clusters [7][8]. The random deployment of WSN nodes have been shown below:

Figure 1‑1 WSN Network with 100 nodes deployed randomly [7]

Statement of the Problem

Heinzelman et al [7] proposed a hierarchical routing protocol, LEACH, to improve energy efficiency for Wireless Sensor (WSN) and make transmission reliable in a WSN. The principle in LEACH concept was the formation of clusters of nodes and among each cluster one node elects itself as a cluster head. The cluster head collects data from all the sensor nodes within that cluster and performs compression and aggregation of data before transmitting it to the base station. LEACH protocol solved the problem of data collection in a very efficient manner, and LEACH achieved 8% improvement over direct transmission of information from sensor node to the base station. This project further attempt to optimize energy while transfer of information from sensor node to the base station in a wireless sensor network.

Main Objective

The main objective was to improve LEACH routing algorithm to improve energy efficiency for WSN.

Specific Objectives

(i) To study energy-efficient routing protocols, and analyze LEACH in particular.

(ii) To implement LEACH protocol in MATLAB and analyze its characteristics.

(iii) To propose improvements in LEACH protocol.

(iv) To compare and validate the proposed scheme over LEACH protocol.

Significance of the Study

Wireless sensors are emerging as the new tool for habitat monitoring. WSNs have found their application in various areas such as health care, wildlife monitoring, emergency response, traffic monitoring, security surveillance. A major challenge for a wireless sensor network lies in the energy preservation of sensor nodes, which limits the network lifetime of WSN. The most important performance measure for wireless sensor networks is network lifetime. Energy efficient routing will help in prolonging the network life time of the wireless sensor network and will improve its applicability.

Scope of the Study

In this project, a new routing protocol, Weighted clustering energy efficient routing algorithm (WCEERA), have been proposed. WCEERA extends LEACH clustering approach. Both LEACH and WCEERA algorithms were implemented in MATLAB. Both protocols were implemented for same random locations of the sensor nodes and same parameters were used in both the schemes so that comparison can be done.

Literature Review

In this section a brief review of all those energy efficient schemes will be given which have been studied.

LEACH Protocol

Low Energy Adaptive Clustering Hierarchy (LEACH) was the first hierarchical cluster-based routing protocol for wireless sensor network (WSN) in which the nodes were divided into clusters, in each cluster a dedicated node with extra energy was called Cluster Head (CH) and that CH was responsible for creating and manipulating a TDMA (Time division multiple access) routine for all the remaining nodes within that cluster to send their sensed data to that CH and then sends that aggregated data to the BS where these data was needed using CDMA (Code division multiple access). Remaining nodes were cluster members. This protocol was divided into rounds and each round consists of two phases;

Set-up Phase

In set-up phase of LEACH-protocol each node decides independent of other nodes if it will become a CH or not. The node that had not been elected a CH for long time was more likely to be elected than nodes that already had been CH.

The nodes which become the CHs then inform their neighborhood by broadcasting them an advertisement packet. Non-CH nodes pick that advertisement packet with the strongest received signal strength. In the next cluster setup phase, the member nodes inform that CH that they had became a member to that cluster by sending back "join packet" which contains their IDs using CSMA. After each cluster-setup sub phase, the CH had the information about all the member nodes within its cluster and their respective IDs. Using all the messages received within the cluster from all the members of the cluster, the CH creates a TDMA routine, and broadcast that TDMA routine to cluster members by picking up their CSMA code randomly.

Steady Phase

In this phase of LEACH-protocol actual data transmission starts; cluster members send their respective data to the CH during their allocated TDMA slot. During this transmission the member nodes uses a minimal amount of energy chosen by them based on the received strength of the CH advertisement packet. The radio capability of each non-CH node can be turned off until the nodes allocated TDMA slot arrives, thus minimizing energy dissipation in these nodes. When all the data has been received from all the member nodes; the CH aggregates that data and send it to the BS. LEACH performs local aggregation of data in each cluster due to which the amount of data to be transmitted to the base station is being reduced. Although LEACH protocol acts in a good manner, but still it suffers from many drawbacks such as;

Random selection of CH, that does consider energy consumption.

It can't cover a large area.

Non-uniform distribution of CHs; where CHs can be located at the edges of the cluster.

There were lots of deficiencies in the LEACH protocol, so certain improvements were made in LEACH protocol. Some of them are described below:

E-LEACH protocol

In Energy-LEACH protocol the CH selection procedure of LEACH protocol was improved. It considers the residual energy of the node as the deciding parameter after each round that wether that node had been elected as CH before or not. E-LEACH protocol is also divided into rounds. In the first round; every node has the equal probability to become the CH so in first round nodes are randomly selected as CHs. In the next rounds, since the residual energy of each node is different so now the residual energy of the nodes is taken into account for the selection of the CHs. Hence the nodes having more energy will become a CHs rather than the nodes having less energy.

TL-LEACH

Another drawback of LEACH protocol was that the CHs were collecting and aggregating data from sensors in their own cluster and then were passing the aggregated information directly to the base station. There can be a certain possibility that CH might be located far away from the BS, so it was using lot amount of its energy for transmitting the information towards the base station and because it was always sending from that much distance with same energy so it was getting die faster than other nodes. Hence a new version of LEACH protocol was proposed which was called two-level Leach. In this protocol; the CH was collecting data from other cluster members same like original LEACH, but rather than transfer that data directly to the base station it sends it to a CHs that lie between that CH and the base station.

M-LEACH protocol

Although TL-LEACH was an improvement over LEACH but still it was not that much efficient in preserving the energy. So another protocol Multihop-LEACH was proposed, In Multihop-LEACH protocol the optimal path is being selected between the CH and the BS through other CHs and these CHs acts as a relay station to transmit the data over through them.

First, multi-hop communication is being adopted within CHs. Then, according to the selected optimal path, these CHs transmit data to the corresponding CH which is nearest to BS. Finally, this CH sends the data to base station. M-LEACH protocol was almost the same as LEACH protocol, only makes communication mode from single hop to multi-hop between CHs and BS.

LEACH-C Protocol

In LEACH protocol no guarantee was being offered about the placement and/or number of cluster heads. Hence an enhancement over the LEACH protocol was being proposed. The protocol was called the LEACH-C protocol that uses a centralized clustering algorithm but the same steady-state phase as LEACH protocol. In LEACH-C protocol better performance was produced by spreading the cluster heads throughout the network. During the set-up phase of LEACH-C, each node broadcasts the information about its current location (possibly determined using GPS) and the residual energy level to the base station. In addition to determining appropriate clusters, the base station also had to ensure that the energy load was evenly distributed between all the nodes. In order to do this task, base station was computing the average node energy and was comparing it with energy of all the nodes independently to determine that which nodes had energy below that average.

Once the cluster heads and their associated clusters were being found, the base station then broadcasts a message that obtains the cluster head ID for each node. If a cluster head ID of a node matches to its own ID, that node was a cluster head; otherwise the node determines its TDMA slot for data transmission and went into sleep mode until the time to transmit its data had arrived. The steady-state phase of LEACH-C is same as that of the LEACH protocol.

LEACH-F Protocol

LEACH protocol with Fixed clusters (LEACH-F) was based on clusters that were formed only once and then remained fixed. The cluster head position then rotates among the nodes within the cluster for every round. The advantage with this was that once the clusters were being formed, there was no set-up overhead at the beginning of each round. In order to decide clusters, LEACH-F used the same centralized cluster formation algorithm as was described in LEACH-C.

The drawbacks with this protocol were that:

The fixed size of clusters in LEACH-F did not allow new nodes to be added to the system and did not adjust their behavior based on nodes dying.

LEACH-F did not handle the node mobility.

PEGASIS Protocol

In this protocol the nodes are being organized to form a chain, which can be accomplished in two ways:

The sensor nodes themselves form the chain using a greedy algorithm starting from some random node

Alternatively, the base station itself computes the chain and broadcast it to all the sensor nodes [8].

In order to gather data in each round, each node receives data from one neighbor, then fuses it with its own data, and transmits to the next neighbor on the chain. In each round of communication the leader node will be at a random position on the chain, which is important for nodes to die at random locations.

PEGASIS protocol performs data fusion at every node except the end nodes in the chain. Each node fuses its neighbor's data with its own to generate a single packet of the same length and then transmit that packet to its next neighbor. In PEGASIS each node receives and transmits only one packet in each round and can be the leader for only once in every 100 rounds.

PEGASIS improves on LEACH by saving energy in several stages:

First, in the local gathering, the distances that most of the nodes transmit are much less compared to transmitting to a cluster-head in LEACH.

Second, the amount of data for the leader node to receive is maximum two messages instead of 20.

Finally, only one node transmits data to the base station in each round of communication.

Certain improvements were made in PEGASIS protocol. Some of them are described below:

H-PEGASIS

Hierarchical-PEGASIS (H-PEGASIS) is an extension to PEGASIS, which tries to decrease the delay incurred during transmission of data to the base station. It proposes a solution to the data gathering issue by considering energy delay parameter [11]. For reducing the delay in PEGASIS, simultaneous transmissions of data messages are followed. In order to avoid collisions and possible signal interference among the sensors, two approaches have been suggested:

The first approach incorporates signal coding, e.g. CDMA [11].

In the second approach only spatially separated nodes are allowed to transmit at the same time [11].

During its operation, H-PEGASIS reduces the delay by constructing a chain of nodes that forms a tree like hierarchy. Each selected node in a particular level transmits its data to the node in the upper level of the hierarchy. This method ensures data transmission in parallel and reduces the delay significantly.

C-PEGASIS

One of the most critical problems in PEGASIS is redundant data transmission. The reason for this problem is that the base station's location is not taken into account when one of nodes is selected as the leader node of the chain. Due to this problem the path followed forwarding data from a node to base station may end being too long. The concentric-PEGASIS clustering scheme (C-PEGASIS) is specially designed in order to solve this problem. The enhanced PEGASIS protocol consists of four processes as follows:

Level assignment: Based on signal strength, each node in the wireless sensor network is assigned its own level from the base station, thus forming concentrate circles. The number of these levels to be assigned is dependent on various parameters such as the density of the sensor networks, the number of nodes, or the location of the base station [12].

Chain construction: Within each level area, the chain construction is started at the farthest node from the base station using the greedy algorithm.

Head node construction: One of nodes on the chain at each level area is selected as a head node.

Data transmission: The process of data transmission is same as PEGASIS protocol. At each level all the nodes transmit the data along the chain to the next neighour node from themselves. The neighbor node receives the data and fuses it with its own data and then transmits that data to the next neighbour node. The leader node in each level transmits the data to the lower leader node up to base station

CBERP Protocol

Figure 2‑2 CBERP Routing Protocol [10]

In CBERP the balance of the energy consumption is being kept amongst the leader nodes because it chooses the leader node having the greatest amount of energy for data transmission, hence it helps the whole network to last longer. In PEGASIS protocol which was designed to overcome the drawback of LEACH-C in which the headers were spending too much energy, a chain is being formed through all nodes, but still it creates delays in data transmission because of the long length of the chain, and also the chain might be broken by one dead node in the middle. In contrast to PEGASIS, CBERP however greatly improves the performance for data transmission by decreasing the average length of the chain. In reality, the base station to headers is more likely to die early since they have more chances to do transmission. On the other side, CBERP does not have the same problem since it chains only the headers, and effectively selects the leader of them [10].

In CBERP the energy tolerance limit E is being used in order to advance the header selection method of LEACH-C and to use energy more efficiently.

E = Eresi/EINIT * CHpnt [10]

E` = ∑Eresi/∑EINIT * CHpnt [10]

Where,

Eresi = The remaining amount of energy for the node

EINIT = the amount of initial energy

CH = the header of the cluster

CHpnt = the proportion of the number of the headers to the number of all nodes in the network.

In start the node with the highest residual energy is chosen as a header of the cluster. For successive number of rounds if a newly-calculated value of E is greater than the value of the current header E', the node with newly-calculated value of E becomes a new header. The new header has the right to collect the data from the member nodes and announces that it has become the header to them.

CBERP also guarantees the mobility of the nodes as it time by time re-arrange the clusters over the whole network and the headers continuously inform about the state of their clusters to the base station. Furthermore, CBERP can significantly reduce the overhead caused by selecting new headers since it selects a multiple of candidate nodes and appoints one of them the header whenever the original header is unavailable [11].

LEACH Protocol

Introduction

In a microsensor network there can be hundreds or thousands of sensing nodes. These nodes should be in-expensive and energy-efficient as much as possible so that they can be made reliable for getting high quality results. Efficient routing protocols must be designed to achieve reliability in the presence of individual node failure by minimizing energy consumption.

The data being sensed by the nodes in a wireless sensor network must be transmitted to a base station, where the end-user can access the data. For LEACH protocol the microsensor network is one in which:

The base station is fixed and located far from the sensors [7].

All nodes in the network are homogeneous and energy-constrained [7].

In a sensor network end-user had to process too much data, so there must be automated methods of combining or aggregating the data into a small set of useful information. This helps to shorten the length of data to be transmitted to the base station.

Low Energy Adaptive Clustering Hierarchy (LEACH) was the first hierarchical cluster-based routing protocol for wireless sensor network (WSN) in which the nodes were divided into clusters. The key features of LEACH are:

Localized coordination and control for cluster set-up and operation [7].

Randomized rotation of the cluster "base stations" or "cluster-heads" and the corresponding clusters [7].

Local compression to reduce global communication [7].

Due to the use of clusters for transmitting data to the base station the transmit distance is very small for most nodes, hence only a few number of nodes has large transmit distance in order to send their data to the base station. LEACH protocol outperforms classical clustering algorithms by using adaptive clusters and rotating cluster-heads [7], due to which energy is distributed evenly among all the sensors. In addition, LEACH is able to perform local computation in each cluster to reduce the amount of data that

must be transmitted to the base station. This achieves a large reduction in the energy dissipation, as computation is much cheaper than communication.

Overview

In LEACH scheme a large number of sensors in a field want to communicate with a base-station that is far from them. In LEACH an adaptive rotating cluster-head scheme is used to determine which nodes communicate with the base-station. Rotating cluster-heads are used because of the fact that fixed cluster-heads will die first because of direct communication. In each round a node chooses to become a cluster-head independent of other nodes depending upon its value of probability. Each cluster-head is chosen only once in 1/P rounds where P is the desired percentage of cluster-heads in the network.

The nodes which become the CHs then inform their neighborhood by broadcasting them an advertisement packet. Non-CH nodes pick that advertisement packet with the strongest received signal strength. In the next cluster setup phase, the member nodes inform that CH that they had became a member to that cluster by sending back "join packet" which contains their IDs using CSMA. After each cluster-setup sub phase, the CH had the information about all the member nodes within its cluster and their respective IDs. Using all the messages received within the cluster from all the members of the cluster, the CH creates a TDMA routine, and broadcast that TDMA routine to cluster members by picking up their CSMA code randomly.

The cluster members send their respective data to the CH during their allocated TDMA slot. During this transmission the member nodes uses a minimal amount of energy chosen by them based on the received strength of the CH advertisement packet. The radio capability of each non-CH node can be turned off until the nodes allocated TDMA slot arrives, thus minimizing energy dissipation in these nodes. When all the data has been received from all the member nodes; the CH aggregates that data and send it to the BS. LEACH performs local aggregation of data in each cluster due to which the amount of data to be transmitted to the base station is being reduced.

Simulations have determined that the optimal number of cluster-heads is about 5%.

MATLAB simulations show that LEACH reduces the communication energy requirement by a factor of 8 over direct-transmission and minimal-transmission-energy routing. Also the first node death occurs over 8 times later in LEACH as compared to the direct-transmission strategy.

Cluster-Head Selection Process

Initially when clusters are being created each node decides whether or not to become a cluster-head for the current round .This decision is based on the suggested percentage of clustered for the network (determined a priori) and the number of times the node has been a cluster-head so far. This decision is made by the node n choosing a random number between 0and 1. If the number is less than a threshold value T (n), the node becomes a cluster-head for the current round. The threshold is set as:

Where,

P = the desired percentage of cluster-heads (e.g. P = 0.5)

r = the current round

G = the set of nodes that have not yet been cluster-heads in the last 1/p rounds.

Using this threshold every node will be a cluster-head at some point within 1/p rounds.

Figure 3‑3 cluster head nodes=C at time t1 [7]

Figure 3‑4 cluster head nodes=Co at time t1+d [7]

Limitations of LEACH

Not efficient for large-scale networks.

Fixed percentage of cluster-heads for any size network (5%).

The protocol may lead to concentration of cluster-heads in one area of the network.

It assumes that all nodes can communicate over one hop (directly) with the base station.

Uniform energy dissipation assumed for both cluster-heads and other nodes in any given round.

All nodes start with equal energy residual levels.

Proposed Changes

In order to fulfill the need to limit energy requirement for communication several and thereby increasing the network lifetime some changes have been proposed below to overcome most of the limitations as seen in the base LEACH implementation.

WEECS Protocol

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