System Engineering Design: Robotic Excavation for Water Extraction - Report Example

System engineering design: Robotic excavation for water extraction Group name Your name University ID Course name Submission Date Outline Section 1: Introduction Section 2: Benchmarking Section 3: Trade-off Analysis Section 4: Concept Generation and Selection Section 1: Introduction Human beings are motivated by the fact that Mars has a climate almost similar the earth. This has motivated man to think of exploring Mars and try to create resources which can be used by man as he works and lives in that planet. The first astronauts will require water for use thus there is a need to extract and process water from the surface of Mars as it will be very expensive and complex to transport all resources they will use during their mission. Several methods of extracting water from Mars have been proposed in the past and they include excavation of regolith and heating as well as direct heating of the surface of Mars. Heating can be done using microwaves, solar concentrators, or resistance heaters. This means that a system is required in place to help in extracting and processing water that that is required to be used by the first astronauts. This will be extracted using robotic system. Hydrogen may be imported from the lunar atmosphere thus the robot needs to be designed to be able to carry out these activities. The water will need to be disposed of once it has been used by the system. This paper will design a system that will assist man in extracting water from Mars. This system has six subsystems, which include extraction station structure, station stability, water extraction, water processing, water storage, power source for extraction and protection from Mars dust (Donald, 2007). The system proposed in this paper will be able to serve these purposes — excavating, transporting, processing, storing water and self-Protecting from Mars dust. The system should be able to deal with the rugged ground and protect the equipments from the damage because of the violent convulsions, dust and reactions from chemical that bound the water on the surface. Specifically, system should have the ability of preventing dust from interfering it proper function. This means it should be self cleaning that is in case there is dust system automatically cleans itself (Calle, Buhler, Johansen, Hogue, & Snyder, 201). This system will be lighter than systems that can be installed and used on earth and will be designed to have a low speed. The system will need have the ability to function in temperatures of between -300o to 0o. It should have the ability to generate power and use minimized energy in performing its duty. The system will need to be compatible with all sub-systems that will assist in the extraction of water. This system will not be compatible other systems if it is not stable considering the terrain of Mars, it should also have a sub-system for extracting regolith which contains the required water to be processed. If water is extracted in the form of ice it will be stored in some containers while transporting them for melting and filtering to remove dust and particles. This means will have subsystem of storage tanks and a subsystem of power generation. The heat will need to be generated from a certain source, which is extraction of some materials, which are found in the planet Mars. The system will need to be protected from dust, which may block read to failure. As the extraction continues, the dust is likely to block openings of the system therefore the system needs to be self-regulating to avoid blockage (Cockell, 2005). This is only possible if the system is transparent. This system will be in a form of robot, which will use various technologies such as artificial intelligence, mining technology and terrestrial technology. These technologies will perform large-scale excavation of water from the surface of Mars and they will be remote controlled from the earth. The system will take into consideration the terrain of Mars as well as the mode of material dumping. The system will need to be low energy user, have special and automated operation potential, which will enable it use minimal fluids (Clarke, Willson, and Cooper, 2008). Mars can be assumed a place with low gravity or a vacuum thus the system will need to have the ability to perform in such environment. The extraction will require equipment with the abilities of draglines, which will enable huge extraction of materials. The system will have unique characteristics because of time latency since the time difference between earth and Mars (Clarke, Mann and Wilson 2009). Section 2: Benchmarking Protection from Mars dust The process of water excavation will require a sub-system that will be stable. The system will be stable if it has a continuous power system supply which will be made possible if the System is able to continuously prevent dust from interrupting power generation. This means that there should be a subsystem of self cleaning that is automatic. When there is diction of dust the system should be able to clean within seconds because if it takes long then the system will blocked due accumulation of dust. This will reduce the efficiency of the Robot. Self cleaning ability should be able to detect area that need to be maintained by automatically checking the external appearance of different components of power system. Specifically, the system will have self-inspection the periphery circuit including wire, cable and the connection between the equipments that detects areas to be maintained so as to enable it have continues self-cleaning. The system should also have the ability to prevent thermal radiation device from degradation. This will enable it continually convert the radiation/ heat energy from outside into electricity to maintain the system to work. If it’s not able to protect it-self from radiation definitely it will fail and the mission of mars will be impossible. Equipments and specifications The main aim of the mission is to have a robot that works continuously have constant power supply. This will be made possible by advanced and well designed solar cells that will have the ability to generate power to accomplish more complex missions. Therefore it should have ability to collect maximum power from solar arrays. It should have the ability generate about 180 watts in minimum operating temperature of -160oC. This means that operation temperature is a significant element in the mars rover power system as the average temperature on the Mars is far lower than earth. Furthermore, the solar array has a flat and big area which cannot be insulated from the mars’ atmosphere efficiently. It should have a total mass of between 15g to 20g with duration of between 5 and 10 years. The solar cells that currently exist that can help in designing a solar cell to be used in this mission have the following specifications solar cell unit HPT180-24M HPT80-12M HPT120-24M metric Maximum power W 180 80 120 Open circuit voltage V 44.2 21.6 43.5 Short circuit current A 5.3 4.76 3.65 optimum operating voltage V 38.1 18 35.6 optimum operating voltage A 5.02 4.44 3.37 glass dimension (H*W*D) mm 1574*802*3.2 1200*529*3.2 1030*802*3.2 module dimension (H*W*D) mm 1580*808*50 1205*535*35 1035*808**35 Japan Industrial Standards test Binary pass pass pass unit cost $ 1080 480 720 minimum operating temperature °C -20 -58 -35 Total mass g 20 15 18 duration year 10 5 7 The price of solar cell is estimated to be $6 per watt. The existing solar cell in the market has a total mass of between 15 to 20g. They have glass and module dimension of between 1580 x808 x50 to 1030 x 802 x3.2 as shown in the table above. Overlapping specifications solar cell unit chosen space HPT180-24M HPT80-12M HPT120-24M metric Maximum power W 87.67 180 80 120 module dimension (H*W*D) mm 1000*503*32 1580*808*50 1205*535*35 1035*808**35 unit cost $ 526 1080 480 720 minimum operating temperature °C -52.67 -20 -58 -35 Total mass g 13.33 20 15 18 duration year 6 10 5 7 The overlapping specifications have been listed above and they include maximum power, Module dimension, minimum operating temperature, unit cost total mass and duration. Comparison of benchmarking process on chosen models - The proposed subsystem is expected to meet the requirement of the mission to Mars and like the current system where it is under testing and it is not known. solar cell unit chosen space HPT180-24M HPT80-12M HPT120-24M metric Maximum power W 156.67 180 5 80 2 120 4 module dimension (H*W*D) mm 1000*503*32 1580*808*50 2 1205*535*35 3 1035*808*35 5 unit cost $ 526 1080 1 480 5 720 2 minimum operating temperature °C -52.67 -20 3 -58 5 -35 4 Total mass g 13.33 20 1 15 4 18 3 duration year 6 10 5 5 2 7 3 The performance in different aspect can be evaluated by comparing with the chosen values. In the first TPM, the max power of the solar cell, only E19/320’s performance meets the requirement of target value of 156.67w. Additionally, module dimensions are all quite good in the performance of max load on the panel surface, exceeding 1000*503*32, which can successfully cope with the Mars environment. Considering about the lifetime of the solar cell, the working life of 6 years, the others are only reaching not all requirements. Moreover, only HPT80-12M which weighing 15g, exceeds the target value by small margin. In the operation temperature aspect, all the modules have A range, -58~-20 degrees, which is within the target value: -150~40 degree. However, the chosen target value of -52.67 can be satisfied by HPT80-12M. The operation temperature is significant parameter which ensures the solar can operate normally on the mars. Consequently, all this four modules cannot meet the requirement in the Mars environment because of the defect in the operation temperature. Benchmarking Process Considering the portable and efficiency, the solar array is the best choice for Mars rovers. In the following contents, five appropriate TPMS will be discussed and assigned with specific target value basing on the requirements in the Mars exploration missions. Section 3: Trade-off Analysis Trade-off analysis is important to the systems engineer for it helps in selecting approaches during the functional level of designing process (Eisner 287). It is also relevant during the selection of specific design choices at the process’ subsystem level and for the determination of the sensitivity of the overall system selection to change in weights and ratings accorded to various architectural alternatives. Trade off studies is defined as conducted and documented at various levels of functional, decomposition/ allocation and design alternative decisions. Alternatively, they are specifically designated, to support the decision needs of system engineering process. The detail of a study is thus proportionate to schedule, cost, performance, and risk impacts of the system. Moreover, trade-offs involve user requirements and so other system characteristics are necessary (Clark, 1997; Whitcomb, 2008). Engineering requirements Importance Speed of cleaning Speed of activation Cost of power Coating breakdown strength opacity Continuous dust cleaning 1 9 9 3 3 9 Self-cleaning 2 9 9 9 9 9 Power efficiency 3 3 9 3 9 Thermal radiator degradation prevention 4 9 9 3 3 9 Transparency 5 3 1 9 Total M/S S $ Kv/mil Kv Relationship strength values for Self-cleaning The Speed of cleaning, Speed of activation and opacity has been assigned the value of 9 because self-cleaning will not be possible if the Robot that does not have all this qualities. This means Speed of cleaning factor will have great influence in coming up with a robot that is self-cleaning. Another engineering requirement about the robot is the Speed of activation. The robot is expected to work continuously and in case there slow down due dust or any other reason activation speed becomes very important. This will also make the mission successful. The strength of the relationship between each pair of metrics Speed of cleaning Speed of activation Cost of power Coating breakdown strength opacity Speed of cleaning 9 9 9 9 Speed of activation 3 9 9 Cost of power 1 Coating breakdown strength 9 opacity Justification for the strength values for Speed of cleaning. Speed of cleaning will be affected by the cost of power incurred that is why the value of the relation is 9 which is strong. Speed of activation has a huge impact the speed of cleaning and it affects the entire operation of the robot. The ability to break the coating forming is essential in the speed of cleaning. If the Coating breakdown strength is low then cleaning speed will be low thus affect the time taken to clean the robot. This implies that effectiveness and efficiency of Speed of cleaning will depend on Coating breakdown strength. The value of 9 in the case of opacity and cleaning speed means that there is strong relationship among the two factors. If the system is transparent, it is to notice when dust coat is forming. It is important to note that all metrics paired with Speed of cleaning have given value of 9 meaning a strong relationship. Conflicting pair of metrics Speed of cleaning and cost of power- if we decide to minimize cost of the power that is generated by the solar cell then the speed of cleaning will be lower because it is expected that components used to make the solar cell will be of lower value. At same time we decide to have a high speed of self- cleaning robot and the cost will be high over the same reasons. This means the two are conflicting metrics. Section 4: Concept Generation and Selection Protections from Mars dust – The two sub-functions in the subsystem that rely on each other are storage and processing. Continuous dust cleaning Power efficiency Separate Classification Trees: The atmosphere of Mars can be windy thus it can have a lot dust that needs to be cleaned as the robot is working. This cleaning require constant power supply which can be generated within the system. The size of the solar cell to be used should be able to provide enough energy to the Mars rover and assist in self cleaning. Screening process In the table below + means that the concept is rated better than while 0 means the same and – means it worse off. requirements glass wiper plunge stop Brake Cells lever screw portability 0 + + + + + 0 durability + + 0 0 + + 0 Manufacturing cost + 0 0 - - - - User friendly 0 - 0 0 0 0 0 compatibility 0 0 0 0 0 + - Accuracy + + 0 0 0 0 0 readability 0 - 0 - - 0 + Sum + 3 3 1 1 2 3 1 Sum 0 4 2 6 4 4 3 4 Sum - 0 2 0 2 2 1 2 Net score 3 1 1 -1 0 2 -1 rank 1 3 3 6 5 2 6 Continue yes yes yes No combine yes No From the above concept generation we can state that concepts ranked 1,2 and 3 should be developed further while concept 5 should be considered for development with some modification. Scoring process The scoring were rated using the following scale Relative performance rating Much worse than 1 Worse than 2 Same as 3 Better 4 Much better than 5 Rating wiper cells lever requirements Weight (%) rating weighted score rating Weighted score rating weighted score portability 15 4 0.6 4 0.6 3 0.45 durability 10 3 0.3 4 0.4 4 0.4 Manufacturing cost 15 2 0.3 2 0.3 3 0.45 User friendly 15 3 0.45 3 0.45 4 0.6 compatibility 15 3 0.45 4 0.6 5 0.75 Accuracy 20 4 0.8 3 0.6 4 0.8 readability 10 3 0.3 3 0.3 4 0.4 Total score 3.2 3.25 3.85 rank 3 2 1 Action Develop Develop Develop All three should be develop because their total score is more than three. If it was less than three then it could have been discarded References Calle, C, Buhler, M, Johansen, M, Hogue, M, & Snyder, S (2011). ‘Active dust control and mitigation technology and Martian exploration’, Acta Astronautica, vol.69, p.1082-1088 Clark, D. (1997). “In-Situ Propellant Production on Mars: A Sabatier/Electrolysis Demonstration Plant,” In Situ Resource Utilization Technical Interchange Meeting, February 4-5, 1997, AIAA-97-2764. Clarke, J., Mann G. & Willson D. (2009). Crewed Vehicles for Mars Exploration – Towards a Set of Requirements. Mars Society Australia and School of Information Technology, Murdoch University, South Street. Clarke, J., Willson, D. & Cooper, D. (2008). In-Situ Resource Utilization through Water Extraction from Hydrated Minerals – Relevance to Mars Missions and an Australian Analogue. Cockell, C. S, (2005). Field innovations in support of Martian polar expeditions. In Cockell, C. S. Mars Expedition Planning. American Astronautically Society Science and Technology Series 107: 245-256. Donald, R. (2007). In Situ Utilization of Indigenous Resources. Human Missions to Mars. Los Angeles: Praxis Publishing Eisner, H. (2008). Essentials of Project and Systems Engineering Management. Hoboken, N.J.: John Wiley & Sons. Whitcomb, R. L. (2008). Cold War Tech War: The Politics of America's Air Defense. Burlington, Ontario: Apogee Books. Read More