EPS@ISEP | The European Project Semester (EPS) at ISEP

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report [2013/06/12 00:56] – [7.1 Discussion] team3report [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, we can conclude that the shape of the hull is not a perfect hemisphere, it is bigger. Because we want to obtain the highest safety level as possible, we will make further calculations with the lowest masses: 56,00 kg and 88,30 kg.+Because the results of the practical test differ from the results of the calculations, we can conclude that the shape of the hull is not a perfect hemisphere, it is bigger. Because we want to obtain the highest safety level as possible, we will make further calculations with the lowest masses: 56,50 kg and 88,30 kg.
  
 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:\\
 {{:x7.png?|}}\\ {{:x7.png?|}}\\
-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, for instance due to a wave, the vessel may return to its original position (stable), move away from its original position (unstable), or remain where it is (neutral). \\ 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, for instance due to a wave, the vessel may return to its original position (stable), move away from its original position (unstable), or remain where it is (neutral). \\
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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”, so we can safely say that 3/8 of the mass of stainless steel is underneath the centre of buoyancy. Also the CTD, 1/4 of the fibreglass hull and the ballast will be under the centre of buoyancy.\\+The batteries and the case with the electronics will be situated around the point of buoyancy, therefore they can be neglected. The symmetric stainless steel structure will clasp around the ”Saturn-ring”, so we can safely say that 3/8 of the mass of stainless steel is underneath the centre of buoyancy. Also the CTD, 1/4 of the fibreglass hull and the ballast will be under the centre of buoyancy.\\
  
 **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**\\
-{{:table_6-6.png?200|}}+{{:table_6-6.png?200|}}\\
  
-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, on-surface measurements, data storage and transferring, and power supply. We started to improve and expand that idea what led us to the final solution of the electronic architecture shown in Figure 6-24. +The first general concept was to create several different parts responsible for different tasks, such as: underwater measurements, on-surface measurements, data storage and transferring, and power supply. We started to improve and expand that idea what led us to the final solution of the electronic architecture shown in Figure 6-24. \\
 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, according to the MCU datasheet [57], all 3 SPIs cannot be used simultaneously with all USARTs and UARTs (which are necessary for RS232 connection). This is why only 3 RS232 can be mounted. Also the Wi-Fi module needs an UART interface what reduces the number of RS232 to 2. Wi-Fi however is supposed to be connected to the slave MCU only temporarily for tests. For the future development, when an appropriate master MCU has to be chosen, the Wi-Fi module can be removed from the slave. Why is there no master MCU included in this solution? This is because the master MCU has to be a proper controller, containing an operating system to manage complex functions. Choosing  one, would be too time consuming for this project.
  
-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, according to MCU datasheet [57], all 3 SPIs cannot be used simultaneously with all USARTs and UARTs (which are necessary for RS232 connection). This is why only 3 RS232 can be mounted. Also Wi-Fi module needs UART interface what reduces number of RS232 to 2. Wi-Fi however is supposed to be connected to the slave MCU only temporarily for tests. For the future development, when appropriate master MCU has to be chosen, Wi-Fi module can be removed from the slave. Why is there no master MCU included in this solution? This is because it has to be proper controller containing operating system to manage complex functions, choosing which is too time consuming for this project.\\ +The schematic presented on Figure 6 26 contains only data transferring lines, no electric lines are included there. Finally, the following interfaces are available: 3x RS232 (or 2, which depends on Wi-Fi) from which one is used for the CTD sensor; 1x CAN; 1x SPI; 1x RJ-11 which is used for the wind sensor; 1x USB which can be used either for a connection with the second controller in the future or as a free connector for any other device or sensor.
-Schematic presented on Figure 6-26 contains only data transferring lines, no electric lines are included there. Finally, the following interfaces are available: 3x RS232 (or 2, which depends on Wi-Fi) from which one is used for CTD sensor; 1x CAN; 1x SPI; 1x RJ-11 which is used for wind sensor; 1x USB which can be used either for connection with second controller in the future or as an free connector for any other device or sensor.\\+
  
 === 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, we decided to use 6V batteries. The voltage can be then converted from 6V to 5 and 3.3V what reduces the energy losses. However, the 12V supply is still needed. This can be resolved in 2 ways: 6V to 12V regulator may be used or additional 12V battery may be applied. We decided, for the best power efficiency, to use additional 12V battery (or serial connection of 2 6V batteries, which have to be used anyway). Finally, powering all components will be realized as it is shown on Figure 6-27.+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, we decided to use 6V batteries. The voltage can be then converted from 6V to 5 and 3.3V what reduces the energy losses. However, the 12V supply is still needed. This can be resolved in 2 ways: 6V to 12V regulator may be used or additional 12V battery may be applied. We decided, for the best power efficiency, to use additional 12V battery (or serial connection of 2 6V batteries, which have to be used anyway). Finally, powering all components will be realised as it is shown on Figure 6-27.
  
 {{:figure_6-27.png?200|}}\\ {{:figure_6-27.png?200|}}\\
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 {{:table_6-8.png?200|}} \\ {{:table_6-8.png?200|}} \\
  
-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's datasheet, sometimes only one. If so, the second value could have been easily calculated from the following very simple formula:\\+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's datasheet, sometimes only one. If so, the second value could have been easily calculated from the following very simple formula:
  
 {{:bildschirmfoto_2013-06-11_um_14.54.38.png?200|//}}\\ {{:bildschirmfoto_2013-06-11_um_14.54.38.png?200|//}}\\
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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/connectors and protects them against water. One of these cables will go from an electronic box into a battery box and will contain three wires: 3.3V line, 5V line, GND line. In this case, to make the battery box easily removable form the hull, the cable has to be connected via waterproof connector, such as Bulgin [108]. Second of these cables will go from a battery box up to the interface panel on the upper side of the hull and will contain four wires: 3.3V line, 5V line, 12V line, GND line. It also has to be easily removable so the use of Bulgin connector is necessary. The last (third) cable will be linked between electronics box and interface panel. This one does not have to be easily removable (so use of special connector is not needed) but it has to be thick enough to collect at least 15 wires sending signals to all interfaces. \\+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/connectors and protects them against water. One of these cables will go from an electronic box into a battery box and will contain three wires: 3.3V line, 5V line, GND line. In this case, to make the battery box easily removable form the hull, the cable has to be connected via waterproof connector, such as Bulgin [108]. The second of these cables will go from a battery box up to the interface panel on the upper side of the hull and will contain four wires: 3.3V line, 5V line, 12V line, GND line. It also has to be easily removable so the use of Bulgin connector is necessary. The last (third) cable will be linked between electronics box and interface panel. This one does not have to be easily removable (so use of special connector is not needed) but it has to be thick enough to collect at least 15 wires sending signals to all interfaces.  
 + 
 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.
 +
  
 {{:figure_6-28.png?200|}}\\  {{:figure_6-28.png?200|}}\\ 
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 ==== 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, there are still many goals to achieve. Some of them are highly important and cannot be omitted if the buoy is ever to be placed on the river. On the other hand, some are just possible future additions that could make the buoy more functional. \\ Although we have already put much effort into the project, and a lot has already been accomplished, there are still many goals to achieve. Some of them are highly important and cannot be omitted if the buoy is ever to be placed on the river. On the other hand, some are just possible future additions that could make the buoy more functional. \\
-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, and maybe even cause the buoy to sink. The hull  can be made watertight by placing on it a “rubber skirt” (Figure 7 1) – a piece of rubber tape that is permanently attached to the cover’s outer surface, near its bottom edge, so that when the cover is in place, the tape can create a tight connection with the hull body’s outer surface, thus preventing the access of water.+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, and maybe even cause the buoy to sink. The hull  can be made watertight by placing on it a “rubber skirt” (Figure 7-1) – a piece of rubber tape that is permanently attached to the cover’s outer surface, near its bottom edge, so that when the cover is in place, the tape can create a tight connection with the hull body’s outer surface, thus preventing the access of water.
  
 {{:figure_7-1.png?200|}}\\ {{:figure_7-1.png?200|}}\\
 **Figure 7-1 "Rubber skirt"**  **Figure 7-1 "Rubber skirt"** 
  
-Another method that can be applied is to duct tape the groove between the cover and the hull body. However, it has three disadvantages: it is time-consuming, unprofessional, and most importantly - uncertain, once it might work, and once not. The best solution, but also most radical, would be to create another fibreglass hull whose cover would have a different geometry and features. As far as water tightness is concerned, it is also necessary to acquire appropriate watertight connectors for the interfaces. Secondly, the remaining components, i.e. communication module, GNSS antenna, batteries, communication module, and box for the hardware, need to be acquired. Once all these components are present, they must be somehow arranged, some inside the hull and some on the steel structure, and connected. Moreover, it is necessary to finalize the software and set it running. In this way the buoy will be able to perform its primary purpose: collect, store and send data. Another important feature that is needed to be added is a fibreglass cover for the lower part of the steel structure, as seen in Figure 7 2. Its purpose is to surround the ballast, and space around the tubes so as to protect the CTD and prevent things from deposing on the ballast. Of course, before putting the buoy in the river, some tests would need to be carried out to check if all these modifications are in working order.+Another method that can be applied is to duct tape the groove between the cover and the hull body. However, it has three disadvantages: it is time-consuming, unprofessional, and most importantly - uncertain, once it might work, and once not. The best solution, but also most radical, would be to create another fibreglass hull whose cover would have a different geometry and features. As far as water tightness is concerned, it is also necessary to acquire appropriate watertight connectors for the interfaces. Secondly, the remaining components, i.e. communication module, GNSS antenna, batteries and box for the hardware, need to be acquired. Once all these components are present, they must be somehow arranged, some inside the hull and some on the steel structure, and connected. Moreover, it is necessary to finalize the software and set it running. In this way the buoy will be able to perform its primary purpose: collect, store and send data. Another important feature that is needed to be added is a fibreglass cover for the lower part of the steel structure, as seen in Figure 7-2. Its purpose is to surround the ballast, and space around the tubes so as to protect the CTD and prevent things from deposing on the ballast. Of course, before putting the buoy in the river, some tests would need to be carried out to check if all these modifications are in working order.
  
 {{:figure_7-2.png?200|}}\\ {{:figure_7-2.png?200|}}\\
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 [106] Alibaba, “Alibaba,” 07 June 2013. [Online]. Available: http://www.alibaba.com/product-gs/633898401/High_Quality_Black_Anti_Corrosion_Humidity.html. [Accessed 07 June 2013].\\ [106] Alibaba, “Alibaba,” 07 June 2013. [Online]. Available: http://www.alibaba.com/product-gs/633898401/High_Quality_Black_Anti_Corrosion_Humidity.html. [Accessed 07 June 2013].\\
 [107] I. A. (. S. Bhd, 07 June 2013. [Online]. Available: http://www.iasb.com.my/webshaper/pcm/files/ICS/GEWISS/SelGuideSurfaceMount.pdf.\\ [107] I. A. (. S. Bhd, 07 June 2013. [Online]. Available: http://www.iasb.com.my/webshaper/pcm/files/ICS/GEWISS/SelGuideSurfaceMount.pdf.\\
-[108] Bulgin, „Bulgin connectors,” Bulgin, 2012. [Online]. Available: http://bulgin.co.uk/. [Geopend 03 June 2013].\\+[108] Bulgin, „Bulgin connectors,” Bulgin, 2012. [Online]. Available: http://bulgin.co.uk/. [Accessed 03 June 2013].\\
 [109] Davis instruments, “Anemometer 7911,” [Online]. Available: http://oceancontrols.com.au/datasheet/ocean/kta250_7911_spec_Rev_E.pdf. [Accessed 7 May 2013].\\ [109] Davis instruments, “Anemometer 7911,” [Online]. Available: http://oceancontrols.com.au/datasheet/ocean/kta250_7911_spec_Rev_E.pdf. [Accessed 7 May 2013].\\
 [110] B. W. Kernighan and D. M. Ritchie, “The C programming Language,” 1988 . [Online]. Available: http://net.pku.edu.cn/~course/cs101/2008/resource/The_C_Programming_Language.pdf. [Accessed 28 May 2013].\\ [110] B. W. Kernighan and D. M. Ritchie, “The C programming Language,” 1988 . [Online]. Available: http://net.pku.edu.cn/~course/cs101/2008/resource/The_C_Programming_Language.pdf. [Accessed 28 May 2013].\\
-[111] STMicroelectronics, „STM32F3 Discovery kit firmware package,” 2013. [Online]. Available: http://www.st.com/web/en/catalog/tools/PF258154. [Geopend 04 June 2013].\\ +[111] STMicroelectronics, „STM32F3 Discovery kit firmware package,” 2013. [Online]. Available: http://www.st.com/web/en/catalog/tools/PF258154. [Accessed 04 June 2013].\\ 
-[112] Davis, „Davis Anemometer documentation,” 2013. [Online]. Available: http://www.davisnet.com/weather/products/wx_product_docs.asp?pnum=07911. [Geopend 12 June 2013].\\+[112] Davis, „Davis Anemometer documentation,” 2013. [Online]. Available: http://www.davisnet.com/weather/products/wx_product_docs.asp?pnum=07911. [Accessed 12 June 2013].\\
 [113] The Free Dictionary, “Anchor,” 2013. [Online]. Available: http://www.thefreedictionary.com/anchor. [Accessed 3 April 2013].\\ [113] The Free Dictionary, “Anchor,” 2013. [Online]. Available: http://www.thefreedictionary.com/anchor. [Accessed 3 April 2013].\\
 [114] The Columbia Encyclopedia, 6th ed., “Anchor,” 2013. [Online]. Available: http://www.encyclopedia.com/topic/anchor.aspx. [Accessed 2 April 2013].\\ [114] The Columbia Encyclopedia, 6th ed., “Anchor,” 2013. [Online]. Available: http://www.encyclopedia.com/topic/anchor.aspx. [Accessed 2 April 2013].\\
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