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| report [2013/06/12 00:51] – [6.5 Project Planning] team3 | report [2013/06/12 18:51] (current) – [Appendices] team3 | ||
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| *An important remark to make is the fact that in this test the weight of the fibreglass hull has to be included. We placed the hull in the water were it will cause a force on the surface; then we added water into the hull to enlarge this force. 16,50 kg has to be added to the 2 results. | *An important remark to make is the fact that in this test the weight of the fibreglass hull has to be included. We placed the hull in the water were it will cause a force on the surface; then we added water into the hull to enlarge this force. 16,50 kg has to be added to the 2 results. | ||
| - | Because the results of the practical test differ from the results of the calculations, | + | Because the results of the practical test differ from the results of the calculations, |
| Now we calculated the ultimate maximum mass that can be attached to the fibreglass hull, we will take a look to the loads: | Now we calculated the ultimate maximum mass that can be attached to the fibreglass hull, we will take a look to the loads: | ||
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| The total mass of the loads, placed in the water, will be 44,20 kg. These loads will cause a force equal to:\\ | The total mass of the loads, placed in the water, will be 44,20 kg. These loads will cause a force equal to:\\ | ||
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| - | Out these calculations we can conclude that the buoy will be buoyant and that we can add an additional ballast with a mass of 11,80 kg. If we add this ballast, the fibreglass hull will be submerged until the water level is exactly underneath the ”Saturn-ring”. | + | Out these calculations we can conclude that the buoy will be buoyant and that we can add an additional ballast with a mass of 12,30 kg. If we add this ballast, the fibreglass hull will be submerged until the water level is exactly underneath the ”Saturn-ring”. |
| Another important factor of the buoyancy is the stability. An object can be buoyant, but if it is not stable it can turn over. A floating object is stable if it tends to restore itself to an equilibrium position after a small displacement. For example, floating objects will generally have vertical stability, as if the object is pushed down slightly, this will create a greater buoyancy force, which, unbalanced by the weight force, will push the object back up. Rotational stability is of great importance to floating vessels. Given a small angular displacement, | Another important factor of the buoyancy is the stability. An object can be buoyant, but if it is not stable it can turn over. A floating object is stable if it tends to restore itself to an equilibrium position after a small displacement. For example, floating objects will generally have vertical stability, as if the object is pushed down slightly, this will create a greater buoyancy force, which, unbalanced by the weight force, will push the object back up. Rotational stability is of great importance to floating vessels. Given a small angular displacement, | ||
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| **Figure 6-11 Centre of buoyancy (56,5kg)** | **Figure 6-11 Centre of buoyancy (56,5kg)** | ||
| - | The symmetric stainless steel structure will clasp around the ”Saturn-ring”, | + | The batteries and the case with the electronics will be situated around the point of buoyancy, therefore they can be neglected. |
| **Table 6-5 Mass above the centre of buoyancy**\\ | **Table 6-5 Mass above the centre of buoyancy**\\ | ||
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| **Table 6-6 Mass under the centre of buoyancy**\\ | **Table 6-6 Mass under the centre of buoyancy**\\ | ||
| - | {{: | + | {{: |
| - | We can conclude that, when we add a ballast of 11,80 kg, the point of gravity will be at the same height as the point of buoyancy, whereby we can say that the prototype will not be stable. | + | We can conclude that, when we add a ballast of 12,30 kg, the point of gravity will be at the same height as the point of buoyancy, whereby we can say that the prototype will not be stable. |
| A solution for this problem is to add more ballast. When we add more ballast the fibreglass hull will submerge deeper. We can keep adding ballast until the water level is in the middle of the ”Saturn-ring” (the maximum mass we can add is 44,10 kg). The perfect balance between ballast and the depth of the buoy has to be determined with further tests. | A solution for this problem is to add more ballast. When we add more ballast the fibreglass hull will submerge deeper. We can keep adding ballast until the water level is in the middle of the ”Saturn-ring” (the maximum mass we can add is 44,10 kg). The perfect balance between ballast and the depth of the buoy has to be determined with further tests. | ||
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| **Figure 6-24 Electronics architecture** | **Figure 6-24 Electronics architecture** | ||
| - | The first general concept was to create several different parts responsible for different tasks, such as: underwater measurements, | + | The first general concept was to create several different parts responsible for different tasks, such as: underwater measurements, |
| On the top of the buoy, there will be a GNSS receiver (to define buoy location and synchronise actual time), place for a solar panel, blinking lamp and, the most important, a platform for sensors to measure conditions above the water surface (A). Data from these sensors will be sent via standard interfaces to the control unit (E). There will be also a second platform for sensors needed to be placed under water (B). All data will be collected in a data storage device (C) and then sent to the user using an antenna connected with wireless communication unit (D). The antenna might be placed either on the top or inside the hull which depends on needed signal strenght. Every component that needs electric energy will be supplied by rechargeable battery (F) which will be able to be connected to a solar panel in the future. Components C, D, E, and F (the grey area) will be placed inside the fibreglass hull and protected against water. | On the top of the buoy, there will be a GNSS receiver (to define buoy location and synchronise actual time), place for a solar panel, blinking lamp and, the most important, a platform for sensors to measure conditions above the water surface (A). Data from these sensors will be sent via standard interfaces to the control unit (E). There will be also a second platform for sensors needed to be placed under water (B). All data will be collected in a data storage device (C) and then sent to the user using an antenna connected with wireless communication unit (D). The antenna might be placed either on the top or inside the hull which depends on needed signal strenght. Every component that needs electric energy will be supplied by rechargeable battery (F) which will be able to be connected to a solar panel in the future. Components C, D, E, and F (the grey area) will be placed inside the fibreglass hull and protected against water. | ||
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| **Figure 6-26 Final signal schematic** | **Figure 6-26 Final signal schematic** | ||
| + | The STM32F3 Discovery board supports many interfaces, but 2 of them (SPI and I2C) are already used for built-in peripherals (Gyroscope and E-compass). One SPI is used to connect a microSD card socket and the last one can be used to attach an additional sensor. Unfortunately, | ||
| - | STM32F3 Discovery board supports many interfaces but 2 of them (SPI and I2C) are already used for built-in peripherals (Gyroscope and E-compass). One SPI is used to connect a microSD card socket and the last one can be used to attach additional sensor. Unfortunately, | + | The schematic |
| - | Schematic | + | |
| === 6.3.3 Power supply === | === 6.3.3 Power supply === | ||
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| * 5V - e.g. STM32F3 Discovery board,\\ | * 5V - e.g. STM32F3 Discovery board,\\ | ||
| * 3.3V - e.g. microSD card socket, wind sensor.\\ | * 3.3V - e.g. microSD card socket, wind sensor.\\ | ||
| - | The first solution was to use a 12V battery supply as these batteries are very popular and easy to find. With that approach we would be able to power, for instance, a CTD sensor directly from the battery and we would need 2 voltage regulators to power 5V and 3.3V operating devices. In this case the energy losses spent on voltage conversion would be big because the voltage difference is at least 7V. This is why, after consultation with the supervisors, | + | The first solution was to use a 12V battery supply as these batteries are very popular and easy to find. With that approach we would be able to power, for instance, a CTD sensor directly from the battery and we would need 2 voltage regulators to power 5V and 3.3V operating devices. In this case the energy losses spent on voltage conversion would be big because the voltage difference is at least 7V. This is why, after consultation with the supervisors, |
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| - | Each component has to be grounded to the common ground. Besides the powering wires of currently chosen components, there should be possibility of easily attaching voltage lines into not used interfaces, in order to provide voltage to sensors to be added in the future. This can be done by attaching parallel wires to already existing ones. Exemplary voltage lines are presented on Figure 6-27.\\ | + | Each component has to be grounded to the common ground. Besides the powering wires of currently chosen components, there should be a possibility of easily attaching voltage lines into not used interfaces, in order to provide voltage to sensors to be added in the future. This can be done by attaching parallel wires to already existing ones. Exemplary voltage lines are presented on Figure 6-27. |
| - | To convert the voltage to needed levels we use linear regulators due to low price and availability at ISEP. \\ | + | To convert the voltage to needed levels we use linear regulators due to low price and availability at ISEP. |
| - | As it can be seen at the schematic, there are components named MAX232. These are voltage level converters. They change TTL standard level (used by output signals of almost every microcontroller) into RS232 standard level which uses wider voltage range. MAX232 converters also need external power supply.\\ | + | As it can be seen at the schematic, there are components named MAX232. These are voltage level converters. They change TTL standard level (used by output signals of almost every microcontroller) into RS232 standard level which uses wider voltage range. MAX232 converters also need external power supply. |
| - | In order to know the number of batteries needed for the system to be autonomous (for some period of time), power calculations had to be done. First, we calculated current and power consumption of each component. Sometimes each of these two values was given in device' | + | In order to know the number of batteries needed for the system to be autonomous (for some period of time), power calculations had to be done. First, we calculated current and power consumption of each component. Sometimes each of these two values was given in device' |
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| === 6.3.4 Physical implementation === | === 6.3.4 Physical implementation === | ||
| - | All electronic devices, except the CTD, blinking lamp, wind sensor and antennas, will be placed inside the white fibreglass hull. To make sure they will be protected against water, they can be put inside a small waterproof box (what was broadly described in section 6.2.4 Water-resistance of the hull). On the top of the box there will be two wholes: one for power wiring, second for signal wiring. Wires will be put together into a bigger cable which reduces number of needed wholes/ | + | All electronic devices, except the CTD, blinking lamp, wind sensor and antennas, will be placed inside the white fibreglass hull. To make sure they will be protected against water, they can be put inside a small waterproof box (what was broadly described in section 6.2.4 Water-resistance of the hull). On the top of the box there will be two wholes: one for power wiring, second for signal wiring. Wires will be put together into a bigger cable which reduces number of needed wholes/ |
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| The idea of having an interface panel on the hull is to make the buoy more reconfigurable. The panel will have all interfaces connectors (all of them waterproof) which are for this moment: 3x RS232, 1x CAN, 1x SPI, 1x USB, 1x RJ-11 (or equivalent pin-numbered connector), 1x MCX, 1x SMA. If any new sensor is needed to attach, the white hull does not have to be opened. The layout of this system is simply presented on Figure 6-28. | The idea of having an interface panel on the hull is to make the buoy more reconfigurable. The panel will have all interfaces connectors (all of them waterproof) which are for this moment: 3x RS232, 1x CAN, 1x SPI, 1x USB, 1x RJ-11 (or equivalent pin-numbered connector), 1x MCX, 1x SMA. If any new sensor is needed to attach, the white hull does not have to be opened. The layout of this system is simply presented on Figure 6-28. | ||
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| - | Based upon these facts and the given deadlines we created a “Gantt Chart”. As can be seen in Figure 6 42, the “Gantt” gives an overview on set milestones and linked activities/ | + | Based upon these facts and the given deadlines we created a “Gantt Chart”. As can be seen in Figure 6-42, the “Gantt” gives an overview on set milestones and linked activities/ |
| - | Creating the “Gantt Chart” | + | Once created, |
| - | In Figure 6 42 the final Gantt-chart of team three shown:\\ | + | In Figure 6-42 the final Gantt-chart of team 3 is shown:\\ |
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| - | **Figure 6-42 Final gantt-chart team three** | + | **Figure 6-42 Final gantt-chart team 3** |
| For more detailed planning we also used the “Scrum” model. For a two-week-period we developed “Sprints” which included specific, single tasks that were supposed to be easily handled by one team member. As a matter of fact, also during the single “Sprints” some activities were more intensive than others. Therefore, sometimes two members of the group were dedicated to one task. The model itself offers a perfect overview for all single tasks (Figure 6-43). | For more detailed planning we also used the “Scrum” model. For a two-week-period we developed “Sprints” which included specific, single tasks that were supposed to be easily handled by one team member. As a matter of fact, also during the single “Sprints” some activities were more intensive than others. Therefore, sometimes two members of the group were dedicated to one task. The model itself offers a perfect overview for all single tasks (Figure 6-43). | ||
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| ==== 7.1 Discussion ==== | ==== 7.1 Discussion ==== | ||
| - | This project has proven to be exactly what we thought it would be: difficult and complex, yet interesting and educationally valuable. Before we even started the actual work, we first needed to learn a considerable amount about different types of buoys - what they consist of, and how they perform their functions. It took us quite a lot of time, but it allowed us to have a better view on how to get started and then proceed with further work. There were many things we needed to consider, discuss and decide on. This included, for example, the anchor, lamp, and microcontroller. The two tasks that took up a considerable amount of time and effort were the structure and programming. At this point we regret that we did not have more experience in these fields before beginning the project; perhaps then we could achieve more and with a better quality. Nevertheless, | + | This project has proven to be exactly what we thought it would be: difficult and complex, yet interesting and educationally valuable. Before we even started the actual work, we first needed to learn a considerable amount about different types of buoys - what they consist of, and how they perform their functions. It took us quite a lot of time, but it allowed us to have a better view on how to get started and then proceed with further work. There were many things we needed to consider, discuss and decide on. This included, for example, the anchor, lamp, and microcontroller. The two tasks that took up a considerable amount of time and effort were the structure and programming. At this point we regret that we did not have more experience in these fields before beginning the project; perhaps then we could achieve more and with a better quality. Nevertheless, |
| ==== 7.2 Future Developments ==== | ==== 7.2 Future Developments ==== | ||
| Although we have already put much effort into the project, and a lot has already been accomplished, | Although we have already put much effort into the project, and a lot has already been accomplished, | ||
| - | First of all, the fibreglass hull needs to be made completely watertight. Without this, there is a risk that water might get in and destroy the electronics, | + | First of all, the fibreglass hull needs to be made completely watertight. Without this, there is a risk that water might get in and destroy the electronics, |
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| **Figure 7-1 " | **Figure 7-1 " | ||
| - | Another method that can be applied is to duct tape the groove between the cover and the hull body. However, it has three disadvantages: | + | Another method that can be applied is to duct tape the groove between the cover and the hull body. However, it has three disadvantages: |
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| [106] Alibaba, “Alibaba, | [106] Alibaba, “Alibaba, | ||
| [107] I. A. (. S. Bhd, 07 June 2013. [Online]. Available: http:// | [107] I. A. (. S. Bhd, 07 June 2013. [Online]. Available: http:// | ||
| - | [108] Bulgin, „Bulgin connectors, | + | [108] Bulgin, „Bulgin connectors, |
| [109] Davis instruments, | [109] Davis instruments, | ||
| [110] B. W. Kernighan and D. M. Ritchie, “The C programming Language, | [110] B. W. Kernighan and D. M. Ritchie, “The C programming Language, | ||
| - | [111] STMicroelectronics, | + | [111] STMicroelectronics, |
| - | [112] Davis, „Davis Anemometer documentation, | + | [112] Davis, „Davis Anemometer documentation, |
| [113] The Free Dictionary, “Anchor, | [113] The Free Dictionary, “Anchor, | ||
| [114] The Columbia Encyclopedia, | [114] The Columbia Encyclopedia, | ||
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