Re: ENSC 340 Project Proposal for StairCraft a Stair-Climbing Mechanism

Transcription

1 School of Engineering Science Burnaby, BC V5A 1S6 September 25, 2000 Dr. Andrew Rawicz School of Engineering Science Simon Fraser University Burnaby, British Columbia V5A 1S6 Re: ENSC 340 Project Proposal for StairCraft a Stair-Climbing Mechanism Dear Dr. Rawicz: The attached document, Project Proposal for StairCraft a stair-climbing mechanism, outlines our project for ENSC 340 (Engineering Science Project). Our goal is to design and implement a machine that can carry heavy loads, including handicaps or senior citizens, up and down stairs smoothly and reliably. In the attached proposal, we cover the overview of our proposed product, possible solutions, team organization, budget, funding, timeline scheduling, and team organization. We also discuss alternative solutions and explain why a design is better than the others. consists of six talented, innovative and enthusiastic fourth-year systems engineering students Wayne Chen, Kenneth Cheng, Jeff Hsu, Andy Ma, Michael Tam, and Gordon Yip. If you have any questions or concerns about our proposal, please feel free to contact me by phone at (604) or by at kchengc@sfu.ca Sincerely, Kenneth Cheng Team Manager Enclosure: Project Proposal for StairCraft a Stair-Climbing Mechanism

2 presents a Stair-Climbing Mechanism Project Proposal Prepared by: Kenneth Cheng Wayne Chen Jeff Hsu Andy Ma Michael Tam Gordon Yip Submitted to: Steve Whitmore Andrew Rawicz Jason Rothe James Balfour Date: Sept 25, 2000 Contact staircraft-340@sfu.ca

3 Project Proposal Table of Contents EXECUTIVE SUMMARY...IV 1 INTRODUCTION SYSTEM OVERVIEW POSSIBLE DESIGN SOLUTIONS ELECTROMAGNETIC LEVITATION HYDRAULIC LIFTER SPRING AND PULLEY THERMAL EXPANSION ROCKET THRUSTER MECHANICAL MOTOR AND GEAR BOX PROPOSED DESIGN SOLUTION SOURCES OF INFORMATION BUDGET AND FUNDING BUDGET FUNDING SCHEDULE TEAM ORGANIZATION COMPANY PROFILE KENNETH CHENG (TEAM MANAGER) MICHAEL TAM (VP FINANCE) ANDY MA (VP ENGINEER) GORDON YIP (CHIEF MECHANICAL ENGINEER) WAYNE CHEN (CHIEF ELECTRONIC ENGINEER) JEFF HSU (CHIEF SOFTWARE ENGINEER) CONCLUSION...12 REFERENCES...13 APPENDIX...14 ii

4 Project Proposal List of Figures and Tables FIGURE 1: SYSTEM OVERVIEW...2 FIGURE 2: DATA FLOW BLOCK DIAGRAM OF STAIRCRAFT...2 TABLE 1: ESTIMATED PROJECT BUDGET...7 FIGURE 3: PROJECT GANTT CHART...9 FIGURE 4: PROJECT MILESTONE CHART...9 iii

5 Project Proposal Executive Summary Ash is an athletic professor who is interested in playing various sports. Because of an accident, he got injured and currently he has a cast on his leg. Still yet to recover, hard-working Ash is eager to get back to work. So, he falls onto his wheelchair and struggles to his work site one day. Getting closer and closer very slowly to the outside of the building, he suddenly stopped his wheelchair, frowned sadly and sighed deeply. Facing the stairs with 13 steps just before the entrance, Ash is thinking that when he was healthy he could jump over the 13 steps easily, but now it is like Mount Everest standing tall in front of him Ash s story is quite familiar these days. We all know that there are some situations in which only stairs are available and elevators may be too far away. The problem will be solved if the wheelchair itself can climb up/down stairs. Many assisting devices have been invented to help physically disabled people. These people are confronted with many challenges that result from their disability, and mobility is the most significant challenge they have to face. Assisting devices such as wheelchairs and prosthetics are developed to improve mobility. As far as mobility is concerned, the invention of wheelchairs allows injured, handicapped, or elder people, who suffer from declined or permanently disabled mobility, to utilize wheelchairs for assisting their mobility. Unfortunately, as the wheelchair users encounter situations such as staircases or higher/lower steps while they are traveling, they often need to find elevators or ramps to be able to arrive at their destination levels. In some situations where elevators and ramps are not available or too far away, it is more convenient to have wheelchairs capable of bypassing the heights. Our goal, at Beyond The Horizon, is to create a device or a mechanism (called StairCraft) that is capable of climbing up/down stairs. Eventually, StairCraft can be served as an enhancement on wheelchairs. Besides, our device can be applied on cargo carts. Transportation of cargos up/down stairs can be accomplished automatically. Consequently, human labours can be saved and workplace accidents/injuries can be avoided. Beyond The Horizon consists of six fourth-year engineering students with experiences in mechanical and electronics design, software engineering, and hardware assembly. Our budget for this project is tentatively estimated to be $1540 in Canadian currency. However, the budget may change depending upon future design specifications. We are proposing to research, design, and implement our project over a 13-week period. The prototype model will be constructed, fully tested, and delivered in December iv

6 Project Proposal 1 1 Introduction The invention of wheelchairs improves mobility of injured, handicapped, or elder people who suffer from their declined or permanently disabled mobility. To further enhance the mobility of the wheelchairs when staircases or higher/lower steps are encountered, it is the objective of our project to develop a standalone prototype that is capable of bypassing the heights. Our device can also be applied on transporters so that cargos can be transported up/down stairs automatically. With our device, injuries related to heavy cargo lifting in offices, warehouses, and households can be reduced. Normally, the device can travel like a normal vehicle, with controls such as forward, backward, left, right and brake. When users approach staircases, they control the direction of our stair-climbing device via switches and signal it to travel upstairs or downstairs. The control unit processes user input signals, integrates with sensor statuses and outputs to driving motors systematically in order to accomplish the climbing tasks. This document is a proposal providing an overview of our product, possible solutions, budget, funding, sources of information, project scheduling and organization. Alternative solutions are discussed and criticized, and project Gantt and milestone charts are provided.

7 Project Proposal 2 2 System Overview The StairCraft stair traveler transports users or other goods up/down stairs. Based on user inputs and statuses of the sensors, the central processing unit analyzes the input signals and StairCraft reacts by driving its motors. Figure 1 illustrates the relationship between the users, StarCraft, and the stairs. User User Command, Cart Motion Stairs Distance to Stair Steps StairCraft Stair Traveler sensors CPU, motors Figure 1: System Overview Figure 2 illustrates the block diagram of how input data is processed through each component within StairCraft. Sensor data Data Acquisition Wheel-driving Motors User Input Cart Direction Platform Level Start/Stop CPU Lifting Motors Steering System Braking System Figure 2: Data Flow Block Diagram of StairCraft

8 Project Proposal 3 3 Possible Design Solutions The goal of the project design is to lift heavy objects up and down stairs. The following possible design solutions can be considered as the final design of the climbing mechanism. The major factors to be considered for the final design proposal include power consumption, ratio of lifting power to weight, mechanism complexity, and production cost. Safety and stability are also important issues if the same design is adapted and made to lift a wheelchair in the future. 3.1 Electromagnetic Levitation This method uses electricity to generate magnetic repulsive force in order to support an object in the air against gravity. The advantage of this method is that there is no physical contact between the device and ground surface; therefore, wear-out due to friction is almost nonexistence. Furthermore, there will not be much corrosion on metal parts. As a result, the reliability of the product is high and the product life cycle can be fairly long. The major concern of this approach is levitation displacement. The magnetic force fades drastically with distances. Also, the power required to create such strong magnetic fields that can support a few hundred pounds of weight is huge. It may not be easy to package a huge battery in a compact space. 3.2 Hydraulic Lifter Hydraulic lifters use air/fluid pressure to lift an object. Usually, hydraulic lifters can be found in heavy-duty mechanisms that have a load capacity of few tons. The major advantage of using hydraulic lifters is that it can lift heavy loads relatively easily. Hydraulic lifters are also quite precise in adjusting heights. However, an air compressor must be used to change the pressure inside the hydraulic lifter. In that case, it might be hard to integrate into the design due to our requirements of compact size and low power consumption. Also, another disadvantage is that it is too expensive and using it in a small device with a relatively light load is not cost-effective. 3.3 Spring and Pulley When a spring and a pulley are combined, the result is a pair of mechanisms that can be adjusted to lift heavy weights. With two pulleys attached to both ends of a spring, the height of the spring can be adjusted by rapping a string around the pulleys. Normally, the string is tightened so that the spring is compressed and stays in the low position. When the string is released, the spring is released so that the platform is lifted up. The advantage of this mechanism is that it is simple and cheap to build. A simple mechanism means it would be easier to build, to maintain, and to fix. The mechanism is more reliable. The disadvantage of this design is that it requires a very strong spring to lift a heavy load. In addition, heavier loads may compress the spring, causing the lifting height to be shorter than expected. To compress a strong spring, it requires a strong motor, which may be large in size, consume more power and cost more money.

9 Project Proposal Thermal Expansion This high-energy consumption method is to use the thermal expansion properties of a metal to lift the load up and down. Generally, when metal is heated, material expands. When metal is cooled, it contracts. The advantage of this method is that there is no connection points which may get loose over time. The major problems of this design are the power consumption to heat up and cool down the metal and the time period for material to expand/contract for a large displacement. Another problem is that we do not know if there is such material that can expend a couple of feet when heated. Even if there is, a change in the surrounding temperature may cause the design to fail as well. 3.5 Rocket Thruster Rocket Thruster might be a possible lifting mechanism in the future. The purpose of a rocket thruster is to generate enough air thrust to work against gravity so that the object can lift up in the air. The major advantage of the method is that the lifting displacement can be quite long. It can even provide 3 dimensional motions in the air. The disadvantage of a rocket thruster is that it is expensive, large in size, and consumes lots of fuel even for a very short period of time. Stability and safety is also questionable for a rocket thruster. 3.6 Mechanical Motor and Gear Box This is the most traditional and cost effective solution of lifting an object. The lifting mechanism can be achieved with a proper mechanical design such as scissors lift, attached with a high torque driving motor. The limitation of the load capacity mainly depends on the torque load on the motor. This design requires less expensive devices and consumes less power. 3.7 Build a Ramp One of the alternative solutions is to build a ramp everywhere people with disability would go. The advantage of this design is that it can be built and treated as public property so its usability range is much greater. The disadvantage of this approach is that it is not affordable for individuals. The government must cover the cost to build the ramps. However, it could be a good solution to be applied in private property. Another major problem to this alternative solution is that it is impossible to add ramp to where it is necessary in already existing building and it waste much space to build ramps in a building.

10 Project Proposal 5 4 Proposed Design Solution Our proposed design solution is to build a mechanism that can lift heavy objects up and down stairs. Such a device can be very useful in assisting handicaps on a wheelchair to move up and down the stairs when situations apply. Also, with our device installed on transporters, heavy cargo lifting in offices, warehouses, and household can be accomplished automatically. Thus, the chances of injuries for people can be reduced. With the amount of time and funding given for this project, we aim to finish a bare-bone StairCraft, which only carries cargoes instead of humans. The prototype is a platform with wheels, sensors, controls, and lifting mechanism and it moves under its own power supply. With more time and funding, we would be able to adapt this stair climbing mechanism to a redesigned wheelchair. Therefore, handicaps will benefit from using StairCraft. The StairCraft can move forward, backward, turn left, and turn right electronically with the control buttons on the control pad. However, the user has to leave StairCraft to climb the stairs on its own for safety reason. The sensors will tell the distance between the stairs and itself and the device will know when to lift up to climb. In choosing the lifting mechanism, we will go for the mechanical design for the following reasons. For electromagnetic levitation, the technology exists, but it is simply too expensive and complex for us to build and use. For the hydraulic lifter, it is a good alternative, but the supporting mechanism required to work with it and the weight of them will be too big and too heavy for our device to handle. For the spring and pulley, it is probably the simplest design, but the strong spring and motor required to compress the spring would cost a lot and consumes too much power. For the thruster design, it is simply out of our reach, even NASA would have a hard time applying the technology to such small device and make it economically profitable. For the thermal expansion, it is a good idea, but we do not know if there exists such material that can expand a couple of feet. Furthermore, it would take a lot of energy to heat it up and cool it down and the environmental temperature could be a critical factor. From the above possible lifting mechanism design proposals, the mechanical design should best fit our goal based on the amount of time and funding we have. Moreover, this design is more within our reach. We have taken courses in mechanical analysis so it is easier for us to build and maintain the entire mechanism on our own to save money. Because this design requires only the parts and materials we can buy in our local Home Depot, we could save some more money. The mechanical design can also decrease the cost of maintenance due to its simplicity.

11 Project Proposal 6 5 Sources of Information In researching and solving our problem, we will be obtaining information from a variety of sources. Course textbooks, reference books from libraries, and research papers from different journals will be used to help in the theory, analysis, and implementation throughout various phases of the project. The worldwide webs will also likely be one of the major sources for providing a wide range of information relevant to our project. For example, some websites have been found that suggest some alternative solutions to our problem. Furthermore, some other websites help in materials resources by providing the addresses of some local hardware companies, such as CasterLand, BC Bearing, and Home Depot, which they have been visited. The technicians in the hardware stores can provide us with some advices and insights for choosing hardware components. Some undergraduate students in Engineering Science at SFU have previously worked with micro-controllers and related projects and can be contacted for information when necessary. In addition, Dr. Shahram Payandeh, an ENSC professor who specializes in robotics and mechanical engineering, can provide valuable advices regarding kinematics and dynamics analysis of our proposed mechanical designs. Also, a relative of one of our group members is professional in household renovations and will be kind enough to lend us some machine shop tools for hardware cutting and assembling as well as giving us advices on metal work.

12 Project Proposal 7 6 Budget and Funding 6.1 Budget Table 1 provides a speculative estimation for the budget of our project. Table 1: Estimated Project Budget Required Materials Estimated Costs (CDN $) Bearings / PVC Tubes (Self Made) 40 Light Pressure Switch / Sensors 120 DC Motors (Gearboxes) 500 Springs / Elastic Bands 20 Casters (Wheels) 100 Twin Lead Screws (Self Made) 100 Steel and Aluminum 200 Microprocessor 10 User Interface 80 Other Electronic Components 50 Battery Supply 100 Domain name ( Cost 20 Total Estimation % Mark Up 200 Grand Total of our Estimation 1540 The budget is subject to change as we come up with simplifications that may help to cut the costs of the project. The total cost for our project is approximately $1340. To allow for error in our estimation, we have marked up our total by 15%, which equals to $1540.

13 Project Proposal Funding Since this project requires various mechanical components, the total cost will be very expensive. Therefore, our team is currently considering several sponsors to help fund our project. We will be applying for the APEG Opportunity Fund, the Engineering Undergraduate Student Society Endowment Fund, and the Wighton Development Fund. We are confident that our application for funding will be successful because our staircase climbing mechanism is an innovative and useful idea that has the potential to develop into a variety of bigger and better projects that we may explore in the near future. One such project includes building a handcart that transport goods like pop cans and other heavy items to places where elevators are unavailable. Furthermore, our mechanism may eventually develop into a stair craft specifically designed for people using wheel chairs to access places without the use of elevators. Hence, we may be looking into applying funding from the Canadian Institute of Health Research, and various handicap/wheelchair organizations. The amount of money we will generate from various sponsors may not be sufficient to finance the entire project due to the high cost of mechanical materials. As a result, our team is prepared to cover the remaining expense of the project on our own. All costs will be carefully recorded to help calculate the total at the end in which each person will be responsible for one-sixth of the total cost.

14 Project Proposal 9 7 Schedule Figure 3 illustrates the Gantt chart for our 14-week engineering activities on the StairCraft project. Figure 3: Project Gantt Chart Figure 4, on the other hand, illustrates the milestone chart for our project. Week Project Proposal Functional Specification Progress Report 2 Process Report, Demo Topic chosen Progress Report 1 Design Specification, All Parts Sourced Web Site Prototype Built and Tested Figure 4: Project Milestone Chart

15 Project Proposal 10 8 TEAM ORGANIZATION consists of six talented, innovative and enthusiastic fourth year SFU Engineers Wayne Chen, Kenneth Cheng, Jeff Hsu, Andy Ma, Michael Tam and Gordon Yip. Although all of us are in Systems Engineering, we all have slightly different specialties mechanics, electronics, software development, testing, documentation and web programming. Although we have these differences, we share a common goal we all want to make this world a better place, especially for those who need extra care. In order to combine our talent so that we can work together efficiently, we assign everybody with a role that they feel most comfortable in so that they can maximize their contribution to this challenging project. With the scope of this project, we have to distribute specific task to each member so that everybody can work in parallel and finish the project on time. Therefore, Kenneth Cheng, Team Manager, is responsible in organizing and coordinating the team, communicating with individual member regarding their progress and deal with conflicting issues among members. Michael Tam, Vice President of Finance, who brings his financing experience with Tantus Electronics Corp, is responsible for managing budget, funding and also ordering and shopping related issues. Andy Ma, Vice President of Engineering, is responsible to coordinate the hardware and software portion of the project such that there will be minimal error when we integrate the two parts together. Gordon Yip, Chief Mechanical Engineer, is in charge of the technical operations of the project and overall design of the mechanical portion of the project. Also, with his professional knowledge in the Internet and web programming, he is responsible for designing and maintaining our company website (). Wayne Chen, Chief Electronic Engineer, is in charge of designing and assembling all electrical circuit boards, electrical connections, and any other electronic related issues. Jeff Hsu, Chief Software Engineer, is responsible for designing the software required for this project. Also, he will help Gordon Yip in our website s design and maintenance. To ensure proper group dynamics and concise communication, we have designated a meeting time at least once every week to discuss our progress. During our meeting, everybody can contribute and instead of ordering individual to do their job, the manager s responsibilities are to keep the meetings run smoothly and finish in the expected time. Minutes are kept for future reference. In addition, all team members have to send weekly status to keep others informed. Our contact methods include: , ICQ, telephone and fax. Basically we have 3 sub-groups, namely mechanical, electrical and software. More emphasis will be put on the hardware at the beginning. After the hardware portion is done, everybody will then work on software development and testing. However, when a sub-group faces any sort of difficulty, they are free to contact other members in other sub-group for possible solution.

16 Project Proposal 11 9 Company Profile 9.1 Kenneth Cheng (Team Manager) Worked in Motorola Canada and Vancouver General Hospital for my last two work terms as a software developer and assistant project engineer, I gained valuable experience in developing software system. During my 3 years in SFU, I have taken numerous courses from different faculties that give me the background knowledge to assist this project team. Above all, I have good leadership skill allowing me to manage the team. 9.2 Michael Tam (VP Finance) I am a fourth year Systems Engineering student at SFU and my previous coop terms are with Tantus Electronics Corp. and Circon Systems Corp. I mainly worked along the production line from buying raw parts to assembling mechanical components and testing products using various lab equipments such as the oscilloscope and function generator. 9.3 Andy Ma (VP Engineering) I currently enroll in Systems Engineering at SFU and am interested in robotics, mechanical design and software engineering. During my work terms at NDC, I worked as a software developer and gained professional programming experience in C/C++ and Java. I also have experience in drafting, mechanical design and analysis, computer simulations and physical hardware assemblies of devices from previous projects. 9.4 Gordon Yip (Chief Mechanical Engineer) I am a fourth year Systems Engineering student at Simon Fraser University. I have experience in mechanical design, metal work and technical drawing. I have programming experience in various assembly languages and web programming languages. In my previous coop work terms, I also gain experience in project management and task distribution. 9.5 Wayne Chen (Chief Electronic Engineer) I am currently a fourth year SFU Systems Engineering student. I have software engineering experiences in C++ and VB. As for hardware, I have work experiences in instrument calibration, mechanical design, soldering, circuit board testing, and trouble-shooting. My main interests are microelectronics design, Pspice simulations, and engineering materials. 9.6 Jeff Hsu (Chief Software Engineer) I am a fourth year undergraduate Engineering Science student at SFU. My past co-op working experience includes positions as a Quality Assurance personnel at MDSI and software engineer at Aerosurge Inc. Qualifications in programming include assembly language, Pascal, C, C++, Visual Basic, HTML, and VHDL. Other expertise includes mechanical analysis, electrical analysis, AutoCAD, Flash, Dreamweaver, and PaintShop.

17 Project Proposal Conclusion Beyond The Horizon is dedicated to creating a stair climbing mechanism and bringing enhanced mobility to wheelchairs in such a way that stairs or steps are no longer as obstacles for the wheelchairs. Injured, handicapped, and elderly people retain their freedom to travel on routes that they have once tried to avoid. Our proposed device can be applied to and combined with cargo transporters as well as other machines such as robots that may desire to travel up and down the stairs automatically. The Gantt and milestone charts in the schedule section show that this project can and will be completed in the time frame allotted. We have highlighted our sources of information and research materials. We have presented our potential financial resources, have clearly defined our solution, and have proposed a strategy to achieve our objective. We are confident that by December 2000, when Ash sits on his wheelchair and sees a flight of stairs that have once seemed as tall as Mount Everest, he is able to bypass the heights and explore beyond the horizon.

18 Project Proposal 13 References [1] Casters, < [2] Spiral Lift, < [3] Twin Lead Screw, < [4] FluroNyliner Sliding Bearing, < [5] Catalogue of Electronic Components, < [6] Bearing, < < [7] Hydraulic Cylinder, < [8] Screw Driven Lift, <

19 Project Proposal 14 Appendix

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