System Engineering: Electrically Powered Ultra-light Aircraft (EPUA)

System Overview

Effective monitoring of large pieces of agricultural land is a daunting task which requires the necessary tools and equipment. For instance, in recent days the farmers in remote agricultural areas have been forced to use aerial means of monitoring their farms using different types of light aircrafts. In order to achieve the necessary monitoring of agricultural lands, farmers in remote areas of Australia have expressed the desire to have an Electrically Powered Ultra-light Aircraft (EPUA) to do two primary tasks such as: finding stock and monitoring the presence of feral animals on their properties.

As a result the aircraft requested by farmers should be able to assist them find stock and monitor their property from aerial view through a simple process involving less labour and expenses. Therefore, the aim of this project is to design an Electrically Powered Ultra-light Aircraft (EPUA) that would help farmers in remote areas of Australia to find stock and monitor the presence of feral animals. However, the specific objectives will include: (1) to identify and discuss stakeholders’ needs; (2) to identify and discuss the system requirements; (3) conducting functional analysis and evaluation; and (4) synthesizing candidate solutions and selecting the most preferred solution.

 

2. Needs Analysis

 

User needs are in most cases very high and complex meaning they are likely to conflict among themselves. Thus, carrying out a system needs analysis is very helpful in the identification of the important trade-offs required to take place in course of the design process, and is very crucial in enabling the establishment of the system boundaries. However, for the purpose of determining all the user and system needs, it is important to make sure that all the stakeholders are listed alongside their potential influence on the project. For example, Figure 1 shows the stakeholder analysis for the Electrically Powered Ultra-light Aircraft (EPUA) project.

 

Stakeholders Group	Power	Legitimacy	Urgency	Involvement
Pilots	**	***	***	**
Farmers	****	****	****	****
Aircraft Assemblers and Dissemblers	***	***	***	***
Aircraft Workshop	***	****	****	****
Drivers	**	***	***	**
Insurance	****	***	**	**

 

Figure 1: Stakeholder Analysis

 

Each of the stakeholder groups are characterized using four attributes: power, legitimacy, urgency and involvement as discussed by Kotonya & Sommerville (2010). Since the EPUA will be pilot manned, then the pilots will have a considerable power since without them the acquisition of the EPUA will be unnecessary because there will be no one to operate it. Pilots are also fairly legitimate and urgent, but lack overall involvement since their work only involve operation the EPUA. The farmers are the other stakeholders of this project and they are significantly important in all the four characteristics considered in this analysis: power, legitimacy, urgency and involvement where they are rated at maximum in all. Aircraft assemblers and dissemblers rank relatively high in all attributes since they shall be playing important pre-flight and post-flight roles.

Moreover, the aircraft workshop or manufactures ranks as high as the farmers except that their power is relatively low because they are just implementers of the system needs for farmers. This means they are the actual designers and developers of the system. The drivers have a fair amount of power, but they rank relatively high when it comes to legitimacy, urgency and involvement in the project since the EPUA has to be transportable by a motor vehicle towed trailer. Finally, insurance companies which also constitute another stakeholder to the project have a fair amount of power since they can decide whether to insure the system or not depending on their needs. The insurance companies are also fairly legitimate but they lack urgency as well as overall involvement in the project.

Each stakeholder identified above has different levels of interest and different needs in the project. This means that identification of the stakeholders who have more power in a comparative manner is highly important and recommended. Thus, the needs that are relevant to each stakeholder must be identified in order to determine the ones that are more important.  Furthermore, it is also essential to consider an overall view of the system as a whole by developing a context diagram which is used to show all the outputs and inputs to and from external factors as well as interaction of the system with all the external entities. Figure 2 below shows the context diagram for the EPUA.

Figure 2: Context diagram for the EPUA

The above diagram clearly shows the outputs and inputs to the system while at the same time helping in the identification of the overall needs and boundary of the system. However, in order to clearly help in the identification of the boundary there was a creation of a reference scenario of system. The scenario table is shown in figure 3.

 

Project Name: Electrically Powered Ultra-light Aircraft (EPUA)			Company Name:			Workshop Date 05-Nov-2013
Mission Definition: To design an Electrically Powered Ultra-light Aircraft (EPUA) that would help farmers in remote areas of Australia to find stock and monitor the presence of feral animals
Scenario Building Template
No	Scenario Name	State #	State Description	Trigger to Next State	Next State	Implied Needs	Sizing Factors
1	Finding an electric powered EPUA	1	Procuring the EPUA	Need to find stock and monitor presence of feral animals	2	Ability to find and procure the EPUA
	Scenario Actors	2	Searching for EPUA manufactures	The interest of farmers	3	Determine a manufacturer	Doing search for the manufacturers
	Assembling and charging the EPUA	3	Ensuring there is assemblage workshop and electric power for charging	To allow EPUA operate	4	Ability to operate	Easy assemblage and ability to be operated by electricity and rechargeable
	Scenario Environment	4	Searching for EPUA with necessary specifications	Ability for EPUA as desired	5	Ability to fly for at least 1 hour Has ability to be recharged at 230 Hz	Chargeable and maintain the charge Maintain the necessary flight time
	Monitoring the agricultural land	5	Attempts to fly the EPUA	EPUA effectively finding stock and monitoring for feral animals presence	6	Ability to detect feral animals within the land using a 10 megapixel camera Ability to monitor 100 square kilometres Ability to control speed and power charge	Animals detection range Sensitivity to space Monitoring a wide range of agricultural land
	Dissembling	6	To allow the EPUA to be transportable	To disengage the system
	Threats/Opponents
	No threat or opponents which have been detected because all the requirements have been met.

 

Figure 3: Reference Scenario for the EPUA

 

 

After identification of the stakeholders, and developing a context diagram as well as a reference scenario table, the system needs were then determined as shown in Table 1 below.

Table of Needs

Needs to be accurate

Needs to be electrically operated and rechargeable

Needs to easily assembled and dissembled

Needs to easily transportable by motor vehicle towed trailer

Needs to have at least 1 hour flight time

Needs to be able to monitor at least 100 square kilometres

 

Table 1: Table showing the System needs

 

3. Requirements

 

3.1. Scope of Requirements

The function and performance requirements for an Electrically Powered Ultra-light Aircraft (EPUA) are described in this document. The system will provide the farmers with an effective method of aerial monitoring of feral animals in their properties as well as finding stock.

3.2. Applicable Documents

 

Document Number	Document Title
ISO/IEC/IEEE 29148	Department of defence Standard practice: defence and program-unique specifications format and content
MIL-STD-961E	Systems and software engineering-Life cycle processes-Requirements engineering

 

 

3.3 Requirements

3.3.1 States and modes

3.3.1.1 Modes of Operation: The EPUA shall have three modes of operation; EPUA ON, EPUA OFF and EPUA Searching.

3.3.1.2 EPUA Disassembled: When in EPUA OFF mode, the system will not be able to monitor the agricultural field.

3.3.1.3 Assembled: The EPUA shall be able to monitor when in operation.

3.3.2 Performance characteristics

3.3.2.1 Flight Time: The EPUA shall take a minimum of 1 hour flight time.

3.3.2.2 Feral Animals Identification: The EPUA shall correctly identify feral animals in the farms within a range of 100m using a 10 mega pixel camera

3.3.2.3 Monitoring Area: The EPUA shall monitor an area of about 100 square kilometres.

3.3.3 Interfaces

3.3.3.1 System Language support: The EPUA shall be to receive commands in English.

3.3.4 Physical characteristics

3.3.4.1 Model Integration: The EPUA shall be able to operate in the remote areas of Australia to monitor feral animals.

3.3.4.2 System Colour: The EPUA shall be available in any colour.

3.3.5 Quality factors

3.3.5.1 System availability: The EPUA shall have an availability of 85% for a period of 10 years.

3.3.5.2 System performance: The EPUA shall be able to effectively perform the intended purpose for prolonged hours during the day and this satisfactory accuracy and precision.

3.3.6 Environmental conditions

3.3.6.1 Visibility operation: The EPUA shall in ambient visibility of at least 200 meters

3.3.6.1 Weather operation: The EPUA shall operate in all weather conditions such as rainy, misty and dry.

3.3.6.2 Ambient Temperature: The EPUA shall operate in ambient temperature ranging from -25^oC to 60^oC.

3.3.6 Design and construction

3.3.4.1 Software update: The APS shall accommodate periodic software updates.

3.3.5.2 System transportability: The EPUA shall be transportable by a motor vehicle towed trailer with a tray not bigger than 2.4 metres long by 1.8 metres wide.

3.3.5.3 System override: The EPUA shall not allow system overriding during EPUA ON mode.

3.3.5.4. Source of power: The EPUA shall be electrically powered and rechargeable from 230v, 50Hz single phase power.

3.3.5.5. Assembling and Dissembling time: The EPUA shall have an assembly time prior to flight of less than 15 minutes from the commencement of unloading from the trailer to being ready for takeoff; and a disassembly time after flight of less than 15 minutes from the commencement of disassembly to being on the trailer and being ready to depart.

 

3.4 Verification

 

Requirement Identifier	Requirement Name	Verification Method	Verification Procedure
3.3.1.1	Modes of Operation	Demonstration	EPUA-1: Physical Demonstration
3.3.1.2	EPUA operation	Demonstration	EPUA-1: Physical Demonstration
3.3.2.1	Flight Time	Test	EPUA-2: Measurement Test
3.3.2.2	Feral Animals Identification	Test	EPUA-5: Functional Operation Test
3.3.2.3	Monitoring Area	Demonstration	Object Monitoring Test
3.3.3.1	System Language support	Inspection/Test	EPUA-6: System Test
3.3.4.1	Model Integration	Demonstration/Analysis	EPUA-3: Comparison/Accuracy Calculation
3.3.4.2	System Colour	Inspection	EPUA-1: Physical Demonstration
3.3.4.1	Software update	Demonstration	EPUA-7: Software Functionality Demonstration
3.3.5.3	System override	Demonstration	EPUA-7: Software Functionality Demonstration

 

 

3.5 Packaging

 

Not applicable

3.6 Notes

 

EPUA-1: Physical Demonstration

This will involve testing the appropriate method manually in order to achieve a passable and repeatable result.

EPUA-2: Measurement Test

This will consist of measuring the specified time for ten repeated times. The method is deemed passable when the measured results reflect a 98% comparison.

EPUA-3: Comparison/Accuracy Calculation

This will consist of comparing the necessary numerical data with the anticipated result. The method is deemed passable when error between both results is less than 2%.

EPUA-4: Object Monitoring Test

This test will consist of system testing using multiple test configurations and an error level of less than 2% in comparison means the method is passable.

EPUA-5: Functional Operation Test

This test will involve both a visual test and physical test of the aspect in focus to determine whether the method is passable.

EPUA-6: System Test

This will consist of testing the EPUA and once it operates correctly, the method will be deemed passable.

EPUA-7: Software Functionality Demonstration

This will involve a demonstration of the functionalities of the system in accordance to necessary requirements and once the appropriate test passes five times the method will be deemed passable.

 

 

4. Functional Analysis & Evaluation

 

Following the requirements analysis and deciding on the list of requirements the next step is to decide what functions the system must perform to meet the requirements. The following table shows the main functions required for the EPUA

 

Maintain 1 hour flight time at minimum

Monitor feral animals using a camera

Operate within 100 square kilometres

Operate in remote areas in Australia

Control speed

Control power charge

 

Table 2: List of main functions for the EPUA

 

 

Observing the performance characteristic requirements from section 3.3, it can be seen that there were many functions that arise including the ones presented below. These performance characteristics enable the EPUA, to effectively monitor feral animals within 100 square kilometres.

Monitoring of Agricultural lands 1.1

 

Figure 4: Functional Hierarchy

 

 

Considering that the functional hierarchy does not fully illustrate the exchange of all the outputs and inputs throughout the system, a functional flow chart was created in order to ensure a clear understanding of the entire system is obtained. Therefore, the functional flow chart for the EPUA is shown in figure 5 below where the sequence of each function is highlighted in a clear manner.

Figure 5: Functional Flowchart

 

 

5. Synthesis of Candidate Solutions

 

After the determination of the functions design solutions must then be identified as well as their alternatives for each low-level function. For each function the design solutions are ranked in a list, and rank the notation (P, R) is used to show their effectiveness where R is risk (0- 3 or more risks, 5-no risk) and P is performance (0-Poor, 5- Excellent). Moreover, solutions can be composed of either: Hardware, Software, Facilities, Material, Data, and People.

However, an evaluation of two functions identified in the previous section it is clearly evident that the two candidates that can be derived are: High Performance EPUA and Low Cost EPUA.

6. Select the Preferred Solution

 

From the previous section it is clear that, two candidate solutions were derived such as a low cost option in addition to a high performance option. Different tools are utilized by both options in order to achieve the same task. However, a low cost option would be highly preferred compared to high performance option because the farmers in remote areas in Australia are mainly concerned with a relatively cheap EPUA with capability to effectively monitor feral animals in their properties as well as taking stock.

7. Description of the Final Conceptual Design

 

As our EPUA will be manufactured for monitoring feral animals in their properties as well as taking stock, it will definitely be targeted to remote markets of Australia. With this in mind, the low cost option was chosen over the high performance option. This is mainly because affordable EPUA but effectively functioning will be able to accurately monitor  feral animals in their properties as well as taking stock and farmers will be able to afford the EPUA. Thus, low priced EPUA will be the best option while at the same time making sure that all the design requirements are included. For instance,  the EPUA is supposed to: (1) be electrically powered and rechargeable from 230v, 50Hz single phase power; (2) have a flight time of 1 hour minimum; (3) be transportable by a motor vehicle towed trailer with a tray not bigger than 2.4 metres long by 1.8 metres wide; (4) have an assembly time prior to flight of less than 15 minutes from the commencement of unloading from the trailer to being ready for takeoff; (5) have a disassembly time after flight of less than 15 minutes from the commencement of disassembly to being on the trailer and being ready to depart. However, all activities associated with preparation for flight, flying and post flight (including trailer loading) to be practical for a single person.

 

 

References

The Australian Department of Defence, (2000). DI-IPSC-81431A, DATA ITEM DESCRIPTION: SYSTEM/SUBSYSTEM SPECIFICATION (SSS). Available at: http://www.everyspec.com/DATA-ITEM-DESC-DIDs/DI-IPSC/DI-IPSC-81431A_3758/ (Accessed on 4^th November 2013).

Harris, C. (2002). Hyperinnovation: Multidimensional Enterprise in the Connected Economy. New York, NY: Palgrave Macmillan.

International Standard ISO/IEC/IEEE 29148, (2011). Systems and software engineering—Life cycle processes—Requirements engineering; First edition. Available at:

http://webstore.iec.ch/preview/info_isoiecieee29148%7Bed1.0%7Den.pdf (Accessed on 4^th November 2013).

Karwowski, W., Soares, M.M. & Stanton, N.A. (2011). Needs Analysis: Or, How Do You Capture, Represent, and Validate User Requirements in a Formal Manner/Notation before Design. Melbourne: CRC Press.

Kotonya, G. & Sommerville, I.  (2010). Requirements Engineering: Processes and Techniques. Chichester, UK: John Wiley & Sons.

Oliver, D.W., Kelliher, T.P. & Keegan, J.G. (1997). Engineering Complex Systems with Models and Objects. New York, NY: McGraw-Hill.

Shermon, D. (2009). Systems Cost Engineering. Melbourne: Gower publishing.

Ramo, S. & Robin, K. (1998). The Systems Approach: Fresh Solutions to Complex Problems through Combining Science and Practical Common Sense. Anaheim, CA: KNI, Inc.

Sommerville, I. (2006). Software Engineering, 7^th ed. Harlow, UK: Addison Wesley.

Thayer, R.H. & Dorfman, M.  (eds.), (1990). System and Software Requirements Engineering.  Los Alamitos, CA: IEEE Computer Society Press.

 

 

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