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Power Supply for a Remotely Operated Vehicle May05-12 Project Plan Client Stealth ISR Engineering Scott Morgan Faculty Advisor Dr. Ajjarapu Team Members Gettler, Jonathan EE Ong, Tai EE White, Adam EE Yau, Wei EE DISCLAIMER: This document was developed as a part of the requirements of an electrical and computer engineering course at Iowa State University, Ames, Iowa. This document does not constitute a professional engineering design or a professional land surveying document. Although the information is intended to be accurate, the associated students, faculty, and Iowa State University make no claims, promises, or guarantees about the accuracy, completeness, quality, or adequacy of the information. The user of this document shall ensure that any such use does not violate any laws with regard to professional licensing and certification requirements. This use includes any work resulting from this student-prepared document that is required to be under the responsible charge of a licensed engineer or surveyor. This document is copyrighted by the students who produced this document and the associated faculty advisors. No part may be reproduced without the written permission of the senior design course coordinator. April 30, 2017 Table of Contents List of Figures......................................................................................................... iii List of Tables .......................................................................................................... iv Definition of Terms ..................................................................................................v 1.0 Introductory Materials ...................................................................................1 1.1 Abstract ........................................................................................................1 1.2 Problem Statement ....................................................................................1 1.2.1 General Problem Statement ............................................................. 1 1.2.2 General Solution Approach ............................................................... 2 1.3 Operating Environment..............................................................................2 1.4 Intended User and Use..............................................................................3 1.4.1 Intended Users .................................................................................... 3 1.4.2 Intended Uses ..................................................................................... 3 1.5 Assumptions and Limitations ....................................................................3 1.5.1 Initial Assumptions.............................................................................. 3 1.5.2 Initial Limitations ................................................................................. 4 1.6 Expected End Product and Deliverables ................................................5 1.6.1 Mobile Power Supply ......................................................................... 5 1.6.2 Test Results ......................................................................................... 6 1.6.3 Manual of Operations and Specifications ....................................... 6 2.0 Proposed Approach and Statement of Work ............................................7 2.1 Proposed Approach ...................................................................................7 2.1.1 Functional Requirements .................................................................. 7 2.1.2 Constraint Considerations ................................................................. 8 2.1.3 Technology Considerations .............................................................. 9 2.1.4 Technical Approach Considerations.............................................. 10 2.1.5 Testing Requirements Considerations .......................................... 11 2.1.6 Security Considerations ................................................................... 12 2.1.7 Safety Considerations ...................................................................... 13 2.1.8 Intellectual Property Considerations .............................................. 14 2.1.9 Commercialization Considerations ................................................ 14 2.1.10 Possible Risks and Risk Management .......................................... 14 2.1.11 Project Proposed Milestones and Evaluation Criteria ................ 15 2.1.12 Project Tracking Procedures .......................................................... 16 2.2 Statement of Work....................................................................................18 Table of Contents (continued) 3.0 Estimated Resources and Schedules .....................................................22 3.1 Estimated Resource Requirements ......................................................22 3.1.1 Personnel Effort Requirements ...................................................... 22 3.1.2 Other Resource Requirements....................................................... 23 3.1.3 Financial Requirements ................................................................... 23 3.2 Schedules ..................................................................................................24 3.2.1 Project Tasks Schedule ................................................................... 24 3.2.2 Project Deliverable Schedule ......................................................... 25 4.0 Project Team Information ..........................................................................26 4.1 Client Information: ....................................................................................26 4.2 Faculty Advisor: ........................................................................................26 4.3 Student Team Members:.........................................................................26 5.0 Summary ......................................................................................................27 6.0 References ...................................................................................................28 ii List of Figures Figure 1: Power Supply Diagram ................................................................ 5 Figure 2: Gantt Chart of Project Tasks ...................................................... 24 Figure 3: Project Deliverable Schedule ..................................................... 25 iii List of Tables Table 1: Definition of Terms ........................................................................ v Table 2: Estimated Personal Effort for Fall 2004 Semester ....................... 22 Table 3: Estimated Required Resources ................................................... 23 Table 4: Estimated Project Costs .............................................................. 23 iv Definition of Terms Table 1: Definition of Terms 35 g /Hz full sine wave Measure of vibration (g=9.8m/s 2 ) CDX plywood Standard outdoor grade plywood C value of a battery The amount of current that a battery can supply per 10 hour period DC Direct current MIL-STD-704C Military standard for electromagnetic emissions testing for government design MIL-STD-810 Military standard for government design UAV Unmanned aerial vehicle 2 v 1.0 Introductory Materials The following subsections describe the project problem, operating environment, intended user, intended use, assumptions, limitations, and deliverables. 1.1 Abstract Stealth ISR Engineering has requested a custom designed power supply for a remotely operated vehicle. Currently, a simple system consisting of a generator, batteries and a load all in parallel is being utilized by the client. This system is consistently overcharging the client’s batteries causing the batteries to fail in a short duration of time. The client would like a design that limits and controls the charging current absorbed by the batteries. The load should be primarily powered by the batteries, not the generator. The team will design a power supply that regulates the charging current into the batteries and provides a direct connection between the load and generator for use when the battery voltage has dropped below a given threshold. The final power supply will be more rugged than existing systems due to longer battery life. 1.2 Problem Statement The problem statement outlines both the general problem and general approach to the problem solution. 1.2.1 General Problem Statement Currently, electrical devices in remotely operated vehicles used by the client are powered by a combination of a battery and a DC generator connected in parallel. An engine turns the generator that charges the battery. The load is directly connected to the battery, which is in turn directly connected to the generator. The client has been having problems with batteries being overcharged. The client would like a new system designed that increases battery life by reducing overcharging and overheating. The generator will only supply power to the load when battery 1 power is insufficient. At all other times, the generator should be solely supplying power to the batteries for charging. 1.2.2 General Solution Approach The client is going to be sending a gasoline engine and generator combination to Ames. The design team will be responsible for taking the output from that generator and supplying DC power at 12V, 5V and 3.3V. Voltage from the generator will first be regulated to a constant voltage to be determined. Direct voltage from the generator will vary significantly depending upon the rotational speed of the engine, which will also vary significantly during operation. Next, the current from the voltage regulator to the batteries will be regulated to charge the batteries at the proper current. Appropriate batteries will be chosen to supply necessary power to the client’s load. A multiple voltage output unit will be connected to the battery bank in order to supply the voltages specified by the client. The output unit will consist of several DC to DC converters that will provide different source voltages required by the client. Battery voltage will be monitored during operation. If battery voltage falls below a set minimum, then the regulated voltage from the generator will be used to replace the power supplied by the batteries to the multiple voltage output unit. A switch will open to prevent current from flowing through the output unit back to the batteries. 1.3 Operating Environment The power supply will be onboard a remotely operated vehicle subject to varying temperature and extreme vibration. The client has specified that the power supply shall be able to withstand temperatures from 125° to –37° Fahrenheit. The power supply will be tested to withstand vibration on a 35 g 2 /Hz full sine wave for 1 hour by the client. The power supply should also be rugged enough to withstand a 5 foot drop from a table onto a ¾” thick sheet of CDX plywood. 2 1.4 Intended User and Use Stealth ISR Engineering will use the power supply for the purpose of providing power at 12V, 5V and 3.3V to electronics onboard a remotely operated vehicle. The following information describes the intended user and the intended uses. 1.4.1 Intended Users Citing security concerns, Stealth ISR Engineering has decided to withhold specific information regarding the final use and users of the power supply. It seems reasonable to assume that users of this product will be properly trained to handle such equipment. 1.4.2 Intended Uses The power supply will be used by the client on an unspecified unmanned aerial vehicle. The power supply will have to operate unspecified electronics onboard the aircraft. The design team will develop a rugged power supply in the event that the power supply will have to operate mission critical systems. 1.5 Assumptions and Limitations The assumptions and limitations outlined herein will be used in designing the desired end product for the client. 1.5.1 Initial Assumptions The following assumptions have been made regarding the power supply design. The generator output voltage can be regulated while the generator is operating between 2,500 and 13,000 rpm. Current flowing into the batteries can be regulated. Only one voltage will be used at a time from the power supply. 3 If the designed system will operate within specifications on the surrogate engine and generator assembly being sent to the design team by the client, the power supply will also operate within specifications on the engine and generator that the client will actually be using on the remotely operated vehicle. End users will have the proper training to maintain and install the end product. 1.5.2 Initial Limitations The following limitations will be part of the power supply design. The generator will be a brushless motor driven directly (1:1 gearing) by a 4-cycle gasoline engine. The power supply will output the following voltages: o DC 12 V +.4/-.2 V o DC 5 V +.2/-.1 V o DC 3.3 V +.1/-.05 V The power supply must be capable of supplying 150 watts continuous power at DC 12 V. There shall be less than .05 Vrms noise in the output voltage. The power supply will have overvoltage and undervoltage protection for voltages outside the acceptable range for more than 1 ms. The batteries must be capable of supplying the rated power for 15 minutes without being charged simultaneously by the generator. Emissions shall conform to MIL-STD-704C. The power supply shall conform to size and weight requirements to be specified by the client as soon as possible. 4 1.6 Expected End Product and Deliverables The expected end product will be a prototype mobile power supply for use in a UAV. Test results and a manual of operations and specifications will also be delivered to the client. The mobile power supply will consist of all electronics used from the generator output to the specified output voltages. 1.6.1 Mobile Power Supply At this time, the design team expects the deliverable electronics to include but not be limited to: A voltage regulator to regulate generator output. A current regulator to limit charging current to the batteries. A bank of batteries. Electronics to facilitate switching of load between the batteries and generator directly. Overvoltage and undervoltage protection devices. DC to DC voltage converters to provide the specified output voltages. DC Generator Variable Voltage Voltage Regulator Fixed Voltage Current Regulator Fixed Charging Current Batteries Standard Power Source Auxiliary Power Source Switching Logic Buck DC Converter 12 Vdc Figure 1 Figure 1: Power Supply Diagram 5 5 Vdc 3.3 Vdc 1.6.2 Test Results The deliverable test results will include all specifications of the performed test and the results. The data presented in this document will clearly display the success or failure of the project under the given tests. These materials will be provided to the client as a bound document when the end product is released. 1.6.3 Manual of Operations and Specifications A manual of operations and specifications will also be delivered to the client. Material in this document will consist of the hazards and warnings associated with the power supply, as well as technical documents on the components included in the design. This material may be presented as a bound document for the client or may be a folder consisting of data sheets. Any hazards or warnings associated with the power supply will be clearly defined in the manual of operations. 6 2.0 Proposed Approach and Statement of Work The proposed approach and statement of work provide the team with a plan of action for the remainder of the design period. 2.1 Proposed Approach The following subsections will list, in detail where appropriate, the requirements and considerations incorporated into the project. This section will specify what the project is intended to do, as well as what the project is not intended to do. 2.1.1 Functional Requirements Functional requirements are intended to clearly define what the project should and should not do. The power supply should output three nearly constant voltages. o 3.3 Vdc with voltage variation within +.1/-.5V o 5 Vdc with voltage variation within +.2/-.1V o 12 Vdc with voltage variation within +.4/-.2V Each output voltage should have a voltage ripple of less than .05 Vrms. For the application of this power supply in a UAV, fluctuations in voltage must be strictly maintained to assure no equipment damage or power failures occur. The power supply should output 150 watts continuous power at 12 volts. The client has indicated that 150 watts may be unachievable at the lower voltage levels, in particular the 3.3 volt and 5 volt levels, due to the accompanying high currents. At these voltages the client would like the team to “push the envelope,” allowing the supply to produce as close to 150 watts continuous power as is reasonable. The circuitry of the project should contain circuit protection amenities. For any unacceptable voltage the power supply is subject to for a duration of more than 1ms, the circuit must have a protection system incorporated to defend the system. The power supply should comply with the MIL-STD-704C. The power supply must not cause interfere with other components on the UAV. 7 The design of the power supply should incorporate the use of batteries that will supply the system rated current for a duration of 15 minutes. The application of the power supply will be used in an environment where the generator may not be active, resulting in all power requirements be supplied by the battery for a period of time. 2.1.2 Constraint Considerations Constraint considerations are items that limit physical tolerances, economical tolerances, or any other tolerance that affects the final form of the end product. 2.1.2.1 Physical Strength The power supply will be incident to harsh environmental conditions and must be able to operate under the following conditions: o Temperature range of 125° Fahrenheit to -37° Fahrenheit o 5 temperature cycles of 1° every 5 minutes, as specified in the MIL-STD-810 o Saturation in each extremis temperature for 15 minutes The power supply shall be designed to withstand vibrations of 35 G squared Hz full since wave for 1 hour. This vibration constraint should comply with MIL-STD-810. The power supply shall withstand a 5 foot drop onto ¾” CDX plywood, as specified by the client. 2.1.2.2 Weight and Dimensions The designated area in the UAV will need to be shared between the gasoline motor, generator, batteries, and power supply. These four major components need to be designed with considerations of one another to ensure maximum utilization of the available space. Stringent weight constraints will also be applied to this project, as with any aviation related project. These size and weight constraints are currently unknown, although the client has indicated that specification of these constraints will become available on or before September 24. 8 2.1.2.3 Cost The revenue for the project is $500. Consultation with the client may result in more project revenue, as discussed in previous team-client communications. 2.1.3 Technology Considerations Several technologies will be used in the development of the power supply. Technology considerations include available products that will save time and money in the completion of the power supply as well as indicate areas that should be researched before a selection can be made. Several semiconductor technologies are available for selection research. Thyristors, transistors, and diodes are some of the available products that may be selected. The high current capability of the power supply indicates that MOSFET type devices may be a good choice. The power supply will need to convert DC power to several different voltages. Depending on the output voltage from the generator, there are several types of converters to choose from. Research will need to be completed on the following technologies: o Buck Chopper o Boost Chopper o Buck/Boost Chopper The generator that will provide the link from mechanical power to electrical power should also be researched. The client has specified a brushless DC generator, although research on the excitation voltage and operating RPM should be completed. Batteries for the back up capability of the power supply must also be researched. Preliminary data from the client indicates dry cell technology or gel cell technology are the two preferred products. Modeling of the generator or the choppers may require the use of software such as Dymola or Spice. These software programs will aid the necessary calculations and allow the team to more quickly and efficiently solve the problem. 9 2.1.4 Technical Approach Considerations The technical approach considerations will allow the team to define the methodologies that will be used in the completion of the power supply. This section will display the approaches considered in the design process. The design of the power supply should be divided into the following four categories. 2.1.4.1 Generator Research and Analysis The client will supply the team with a brushless DC generator and a 4cycle gasoline motor. Research should be completed on the horsepower characteristics of the motor corresponding to the RPM necessary for the electrical requirements of the system. An excitation voltage must be chosen to supply the proper electrical characteristics while the RPM fluctuates from 2,500 to 13,000 RPM. Voltage regulation from the output of the generator should also be researched in this process. This approach will allow the team to build a firm foundation of electrical supply from a mechanical process. 2.1.4.2 Battery Research and Selection The capability of the power supply relies on the battery. The client has specified existing problems with power supplies similar to the one the team will be designing. Research will need to be completed on “c” values of batteries as well as the other constraints listed in section 2.1.2. The team will complete battery selection after proper research is completed and all criteria have been meet. Solving all battery issues is a vital step in solving problems with existing designs used by the client. Consequently, the batteries will be chosen before the remainder of the power supply is designed. 2.1.4.3 Power Converter Design The power converter design process can begin after proper research has been completed on the above two topics. This step will allow the team to analyze the proper type of converter to use. 10 2.1.4.4 Protection and Reliability Circuitry Designing protection and reliability circuitry will be the last design steps. This approach will allow the team to collaborate the individual pieces from above to form a finished product. Criteria specified by the client, such as the overvoltage/undervoltage protection, will be incorporated into this design. The reliability concerns included in this circuitry will assure that all performance criteria have been met. 2.1.5 Testing Requirements Considerations Testing considerations are a significant part of the power supply design. It is important that the team test each component that is built to assure the client that the power supply meets the given constraints. Existing power supplies are an option for the client to purchase, although they do not accommodate the features requested. Therefore, the team’s end product should accommodate all the requested features as well as perform equal to or better than existing power supplies. To effectively test the operation of the power supply, each component will be built and tested individually. Afterwards, the completed system will be tested as a whole. The following items describe the components to be tested and the tests that will be applied: The generator and voltage regulator should be tested under the operating RPM range to assure that a proper voltage is achieved. This will be accomplished by mounting the generator to the motor. The voltage regulator will be connected to the generator outputs. The RPM of the engine will then be varied while a digital multimeter is used to record voltage output of the regulator. The batteries will be tested when fully charged. The batteries will be the sole source of power to the power converter during the test. A 150 watt continuous power load will then be connected to the power converter at 12V DC. Voltages will be recorded every 3 minutes in order to verify that the batteries alone will supply 150 watts continuous power for at least 15 minutes. The power converters will be tested using a digital multimeter and an oscilloscope to measure and record the voltage outputs and the voltage ripple. 11 The protection and reliability circuitry will be tested by following the operation procedure on the equipment while recording data to compare with the individual specifications. This test cannot be fully completed until a prototype has been constructed. The temperature, vibration, and radiated emissions will need to be completed at Stealth ISR Engineering in Eagan, Minnesota. Consultation with the client has indicated that any test that cannot be completed at ISU can be completed at the client’s laboratory. Results of these tests must comply with the MILSTD-810 and MIL-STD-704C. All equipment tests must satisfy the specifications indicated by the client, otherwise the test will be considered a failure. 2.1.6 Security Considerations Security considerations for the power supply design will be considered in two phases. The first phase, or scope, of security is during the development of the power supply. The second phase of security to be considered is end product security. There are several unknown security issues associated with the application of the power supply. Stealth ISR Engineering has chosen to not share confidential information with the design team and has indicated through telephone conversations that confidential information will not be released unless absolutely necessary for the project design. Assuming that the client continues to withhold confidential information, the security considerations of the project for the team are minimized. Security considerations associated with the actual end product may include issues related to patents. It is possible that the innovative design of the power supply may lead to a patent. It will be important to not publicly reveal, in detail, the design of the power supply components. 12 2.1.7 Safety Considerations Safety concerns will be a reoccurring theme throughout the design process of this project. Safety considerations are most important in the use and maintenance of the end product. Manufacturing and disposal safety concerns are minimal. There are several different scopes throughout the project. The scopes have been subcategorized on the following page. 2.1.7.1 Unmanned Aerial Vehicle Scope Stealth ISR Engineering is liable for the safety of the operation of the finished UAV. Several mechanical safety issues must be considered from their industrial standpoint, as well as electrical safety issues. The team will keep in mind the application of the power supply and will incorporate circuitry into the design that will allow the power supply to fail to a safe configuration. The client expects safety issues to be clearly indicated to assure that a failure in the power supply will not result in an unsafe condition for the aircraft or people operating the vehicle. 2.1.7.2 Power Supply Scope The team will need to design the power supply to be within acceptable standards in terms of current ratings and radiated emissions. The project will be capable of supplying large amounts of current and all team members and faculty working on the project must use safe practices around the power supply. 2.1.7.3 Initial Testing Scope The team will be responsible for the initial testing of the power supply in the ISU labs. It is important that the first users of the project are aware of the safety concerns with the project (meaning that the initial users must understand the operation of the system). The power supply will provide large currents that will cause significant damage to humans or surrounding equipment. Extreme caution should be used when performing maintenance or trouble shooting any of the circuitry. 2.1.7.4 End User Scope It is assumed that proper training will be issued to those that will operate the UAV, as well as mechanics or technicians who will install or maintain the power supply. Considerations incorporated into the design of the power supply are as follows: 13 Clear concise labeling of outlets and or switches will help users of the end product become familiar with the functionality of the project. Hazard indicators and warnings should be applied where appropriate on the project indicating areas where extra safety should be taken to avoid injury. 2.1.8 Intellectual Property Considerations The senior design team will be investing many hours of personal effort into this project. The team feels that it is important that they be properly recognized for their efforts. Accordingly, the team will be careful regarding what documents and ideas are made public, particularly on the design team’s web page. 2.1.9 Commercialization Considerations Commercialization considerations should be developed for the project. Although the project is being designed for a specific application, the power supply will have the ability to be a “stand alone” component used for other applications. Proper documentation should be compiled for evidence of individual thought that may be applied to the design of the power supply. Patents are a possible outcome for the project, considering the wide application that the power supply could apply towards. 2.1.10 Possible Risks and Risk Management The design process of the power supply has several associated risks. The team members need to accurately and honestly document all work completed. All team members realize that there is a possibility that someone will leave the project (internships, family issues, death, etc.). The team’s strategy for managing risk is to properly document the work completed so that new members may be added to the project and will have the ability to begin work where previous members ended. The team will also keep electronic documents of all materials including hard copies of 14 documents. The project leader as well as the communication coordinator will back up electronic materials. 2.1.11 Project Proposed Milestones and Evaluation Criteria The project team has selected eight measurable milestones, listed below, for use in evaluating this project. Each milestone is accompanied by a weighted percentage which corresponds to component importance. 2.1.11.1 Measurable Milestones Problem Definition (18%) o Problem Definition is the process of getting a clear picture of what existing system the team is going to be given by the client (input), and knowing what the client wants to be the output of the final system to be once the designed hardware is added to the existing system. Research (16%) o Research is the process of getting the required background knowledge to be able to make wise decisions when deciding how to design the needed hardware for the client. Research will be necessary in order to evaluate the use of potential technologies. Technology Selection (18%) o Technology selection is choosing the best possible technology to give the client the power supply specified while staying within the project budget. End-Product Design (18%) o End-product design is comprised of the written specifications and decisions on what hardware components will be used in the end-product, and how those hardware components will be assembled into a power supply for the client. Prototype Implementation (10%) o Prototype implementation is the stage in which all parts have been assembled into a working, testable product. End-Product Testing (10%) o End-product testing is the process of taking the assembled prototype and testing to see if it meets the client’s requirements. 15 End-Product Demonstration (10%) o End-product demonstration is taking the final product, including changes in the prototype made after testing, and showing the client and faculty the product’s effectiveness. 2.1.11.2 Evaluation Criteria After the completion of every milestone, the team will evaluate that milestone. Each milestone will be rated on one of the following categories: o Expectations exceeded 120% o Expectations met 100% o Expectations almost met 70% o Expectations not met 40% o Milestone not reached 0% The project as a whole will be evaluated by multiplying the weight of each milestone by its evaluation percentage. The resulting number multiplied by 100 will be the evaluation percentage for the whole project. This percentage will be interpreted using the same scale used for individual milestones above. Considering the magnitude of the project, seventy percent will be considered a passing score. 2.1.12 Project Tracking Procedures It is essential that the project team be able to track project success as well as maintain the projected work schedule. The primary tracking procedure that the team will use will be to frequently remove ourselves from the details of the project and evaluate the completion of the end product. The team will strive to meet project requirements, keep the project on schedule and keep the project within budget. 2.1.12.1 Project Requirements Tracking Procedures Project requirements will be tracked by intermittently evaluating current tasks to ensure that they benefit the end project. A clear project definition will help the team meet all requirements of the project. 2.1.12.2 Schedule Tracking Procedures A main focus of the team is to keep on schedule. The use of a Gantt chart will allow the team to assign a flexible schedule of events to the 16 subtasks that must be completed. It is important that realistic data and concerns are incorporated into the schedule. The following is a list of concerns that should be evaluated when making the schedule. Time required to order parts. Time required to replace or fix parts or circuits. Extra time required by underestimating the difficulty of a task. Extra time required in the event of team member illnesses. 2.1.12.3 Budget Tracking Procedures The team has a five hundred dollar budget for the purchase of parts and material. It is important that the project does not exceed this amount, although in telephone conversations the client has indicated that more money may be available. All purchases will be accurately documented and a project balance will be logged throughout the project. There are several factors that will allow the team to stay within the provided budget. They are listed below. Minimize the shipping on parts orders by ordering multiple parts in unison. Reuse any parts that are available within the department or from previous projects. Handle all parts carefully, making sure no items are damaged. Use care when testing any circuitry so that additional parts and time will not be required to fix testing errors (especially true when the team will begin environmental testing and pushing the limits of the components). 17 2.2 Statement of Work The statement of work section lists all tasks that the team needs to complete during first and second semesters from September 2004 through May 2005. Task 1- Problem Definition Task Objective: The goal for this project is to develop a power supply for a small mobile mission system. Task Approach: The team will research the problem in depth and communicate with advisor as well as the client in order to thoroughly understand how to avoid the existing problems with available power supplies. Research resources will include but not be limited to, the internet, textbooks, professors and other technical professionals in the field. Task Expected Result: All the team members will fully understand the project and be able to methodically solve design issues. Task 2-Technology and Implementation Considerations and Selection Task Objective: Use available technologies to design a cost effective power supply for the client. Task Approach: Team members will research through the internet and catalogs, the available technology for system components. Task Expected Result: A rugged and cost effective power supply design for the client. Subtask 2a- Power Output Subtask Objective: Meet client’s design specifications for power delivery. Subtask Approach: Use basic power equations to calculate necessary currents at desired voltage levels, after determining the horsepower abilities of the gasoline engine. Subtask Expected Result: 150W continuous power output at 12Vdc when the generator is being driven from 2,500 RPM to 13,000 RPM. Subtask 2b-Generator Voltage Regulation Subtask Objective: Use voltage regulation to control generator output voltage. Subtask Approach: Purchase or build a quality regulator. Subtask Expected Result: Appropriate voltage for the batteries or DC to DC power converters to use. 18 Subtask 2c-Battery Selection Subtask Objective: Select batteries that meet the client’s size, weight, and capacity requirements. Subtask Approach: Choose the most cost effective batteries that meet the above requirements and can be quickly charged. Subtask Expected Result: The batteries will be able to supply full rated load for 15 minutes without being simultaneously charged. Subtask 2d- Battery Charging Current Limiter Subtask Objective: Protect batteries from being overcharged/overheated. Subtask Approach: The team will design or purchase components to control the current entering the batteries. Subtask Expected Result: The batteries will not overcharge or overheat. Subtask 2e- DC to DC Power Converter Subtask Objective: Convert the generator and battery voltage level to specified output voltages. Subtask Approach: The team will be use Dymola software to create DC to DC converters that meet the requirements. Subtask Expected Result: Output voltages within the client’s specifications. Subtask 2f- Overvoltage/Undervoltage Protection Subtask Objective: Protect loads connected to the power supply from overvoltage and undervoltage conditions. Subtask Approach: Select technology that will protect and correct the circuit if an overvoltage or undervoltage condition exists. Subtask Expected Result: Circuit will automatically protect and correct itself if voltage ratings are violated for more than 1 ms. Subtask 2g- Switching Circuit Subtask Objective: Create a switching circuit to apply generation directly to load if the voltage in battery is low. Subtask Approach: The team will research automatic switching technologies, and choose the technology that best fits the given situation. 19 Subtask Expected Result: The switching circuit will able to switch to the generator if the battery voltage is below a specified threshold. Subtask 2h- Noise Suppression Subtask Objective: Determine if additional components are needed to meet noise suppression requirements. Subtask Approach: Use material from EE303, EE452, and various Signals and Systems courses to evaluate circuit noise. Subtask Expected Result: Total noise less than .05Vrms. Subtask 2i- Temperature Subtask Objective: Ensure that the system can withstand the client’s specified temperature range. Subtask Approach: The prototype will be sent to the client’s lab for temperature testing. This test will be entirely completed by the client. Subtask Expected Result: Circuitry will withstand conditions from 125° to –37° Fahrenheit and 5 temperature cycles of 1° every five minutes. Subtask 2j- Vibration Subtask Objective: Ensure that the prototype can withstand vibration specified by the client. Subtask Approach: The prototype will be sent to the client’s lab for temperature testing. This test will be entirely completed by the client. Subtask Expected Result: The prototype will withstand a 35 g 2 /Hz full sine wave for 1 hour during testing. Task 3- End product Design Task Objective: Use Dymola software to simulate and design the end product. Task Approach: Team will use techniques from EE 452 (Electrical Machines and Power Electronic Drives) lab to complete the schematic. Task Expected Result: Design that is ready for prototype implementation. Task 4 – End product Prototype Implementation Task Objective: Construct a product prototype. Task Approach: Using parts that meet design constraints, construct a prototype power supply. Task Expected Result: A working prototype that can be tested. 20 Task 5- End product Testing Task Objective: Verify that the prototype will meet required specifications. Task Approach: Use laboratory equipment to test the prototype for all specifications. Testing will require the use of oscilloscopes, multimeters, and an RPM gauge. Task Expected Result: Rugged power supply that meets the client’s needs. Task 6 – End product Documentation Task Objective: The team will compose a document for the end-user. This will include; product information, part numbers, troubleshooting suggestions, and maintenance schedules for the product. Task Approach: The team will use the information acquired during the design process to write the end-user manual. Task Expected Result: The manual and specification document will be given to the client with the prototype. Task 7 – End product Demonstration Task Objective: The team will plan a demonstration to present to the faculty advisor and client in EE 491. Task Approach: Schedule and prepare a product demonstration. Task Expected Result: The demonstration should verify that the completed prototype meets both client and class requirements. Task 8- Project – Reporting Task Objective: The designers will clearly report project status throughout the duration of the project to the client, advisor and instructors. Task Approach: The team will keep the client, advisor and instructors informed by sending regular emails as outlined in the class notes. A report will be developed when the project is completed. Task Expected Result: All activities will be clearly documented throughout the project duration. If necessary, anyone new to the project will be able to be brought up to date by reviewing reporting done by the team throughout the project. 21 3.0 Estimated Resources and Schedules When developing the power supply several factors need to be considered. Resources, cost estimates and task schedules have to be planned in order to use time and money efficiently. The following are the estimated resources and schedules for the design team working on a Power Supply for a Remotely-Operated Vehicle. 3.1 Estimated Resource Requirements The following sections will cover the expected personal effort of each team member, other resources requirements and financial requirements for the project. 3.1.1 Personnel Effort Requirements An estimate of the anticipated personal effort of each member of the team is shown in Table 2. Our team will work mainly on tasks one, two and three during the first semester. All other tasks will be completed during the second semester. The team will be designing and testing a prototype. Table 2: Estimated Personal Effort for Fall and Spring semesters Team Task Task Task Task Task Task Task Task Total Member 1 2 3 4 5 6 7 8 Gettler, 23 52 53 30 19 25 31 23 256 Jonathan Ong, Tai 18 53 57 30 19 25 36 18 256 White, 25 50 53 30 19 25 29 25 256 Adam Yau, 22 53 53 30 19 25 32 22 256 Wei Total 88 208 216 120 22 76 100 128 88 1024 3.1.2 Other Resource Requirements An estimated financial budget of materials to be purchased during the work period in order to complete the project is shown in Table 3. Table 3: Estimated Required Resources Team Other Items Cost Hours Hours Parts and Materials a. Project Poster 15 0 $50.00 b. Project Parts 10 0 $500.00 Total 25 $550.00 3.1.3 Financial Requirements This section covers the total financial resources required to conduct the project for the entire year. Table 4 displays all costs anticipated for the first half of the project, including include parts, materials and labor. Item Table 4: Estimated Project Costs Without Labor With Labor Parts and Materials: Project Poster Project Parts Subtotal Labor ($10.30 per hour): Gettler, Jonathan Ong, Tai White, Adam Yau, Wei Subtotal Totals $50.00 $500.00 $550.00 $50.00 $500.00 $550.00 $0 $0 $0 $0 $0 $2636.80 $2636.80 $2636.80 $2636.80 $10547.20 $550.00 $10547.20 23 3.2 Schedules The key to a successful project is meeting deadlines. The team has developed the following projected schedules for the completion of tasks and subtasks through May 2005. 3.2.1 Project Tasks Schedule The project will span the length of two semesters. The project schedule begins in September and will end in early May. The chart on the following page depicts the projected tasks and subtasks to be completed versus the proposed project calendar. Figure 2: Gantt Chart of Project Tasks 24 3.2.2 Project Deliverable Schedule Figure 3 displays the team’s project deliverable schedule. This schedule will cover the entire project (two semesters) and will help the team realize when deadlines are approaching. Figure 3: Project Deliverable Schedule 25 4.0 Project Team Information The project team is composed of four senior Electrical Engineering students. The project sponsor is Scott Morgan of Stealth ISR Engineering. With the guidance of the faculty advisor the team should be able to successfully complete the Power Supply of a Remotely Operated Vehicle on schedule. The following sections contain the contact information for all directly involved persons. 4.1 Client Information: Stealth ISR Engineering Scott Morgan 215 Prescott St. St. Paul, MN 55107 Phone: 651-210-6620 / 651-456-2304 Email: [email protected] 4.2 Faculty Advisor: Dr. Venkataramana Ajjarapu 1122 Coover Hall Ames, IA 50011-3060 Phone: 515-294-7687 Fax: 515-294-4263 Email: [email protected] 4.3 Student Team Members: Jonathan Gettler 1407 Georgia Ave. #2 Ames, IA 50014 Phone: 515-460-2686 Email: [email protected] Tai Ong 3507 Lincoln Way #21 Ames, IA 50014 Phone: 563-650-9073 Email: [email protected] Adam White 112 S Hyland #4 Ames, IA 50014 Phone: 563-357-3542 Email: [email protected] Wei Yau 4400 Westbrook Dr. #21 Ames, IA 50014 Phone: 515-451-9325 Email: [email protected] 26 5.0 Summary Currently, the client supplies power to electrical devices in remotely operated vehicles with a combination of a battery and a DC generator connected in parallel, much like the system in an automobile. The load is directly connected to the battery, which is in turn directly connected to the generator. However, the client has been experiencing problems with batteries being overcharged in this configuration. The senior design team will develop a new system for the client to eliminate the overcharging problem. This project plan will serve as an outline of the activities to be performed by the design team in the next eight months. Project tasks clearly define what actions the design team must take to successfully complete the project. The project schedule in the Gantt chart coordinates when the design team must complete these project tasks. Using the preceding plan, the design team is confident that the product delivered to the client in May will be a complete success. 27 6.0 References 1. Hart, Daniel W. Introduction to Power Electronics. New Jersey: Prentice Hall, Inc. 1997 2. Hobbico Inc. “Surpass Series” Hobbico Inc. 1997-2004. 9/9/04. <http://www.osengines.com/engines/surpass.html> 3. [email protected]. “B40 Series Motors” Hacker Brushless Motors. 9/9/2004. <http://www.hackerbrushless.com/motors_b40.shtml> 4. Karadsheh, Fares, et. al. “Multiple-Output, Variable-Output DC Power Supply (Phase 2) May04-08” Iowa State University. 4/20/2004. 9/02/2004. <http://seniord.ee.iastate.edu/may0408/> 5. [email protected]. “Sullivan Products” Sullivan Products. 2004. 9/08/2004. <http://www.sullivanproducts.com> 28