Difference between revisions of "Turtle Sense/Phase Two"
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*[[User:Mark]] -- Web design | *[[User:Mark]] -- Web design | ||
*[[User:Britta]] -- National Park Service Biologist | *[[User:Britta]] -- National Park Service Biologist | ||
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| + | :''[[Turtle Sense/Division of labor|initial discussions about the division of labor]] | ||
==Overview== | ==Overview== | ||
| − | The plan for Phase Two is to create about 10 communications towers and 20 smart sensors for installation in the Outer Banks of North Carolina during the Spring and Summer of 2013. The | + | The plan for Phase Two is to create about 10 communications towers and 20 smart sensors for installation in the Outer Banks of North Carolina during the Spring and Summer of 2013. When nests are discovered by park personnel, the nests are uncovered, the eggs counted, and a DNA sample is taken. At that time, a smart sensors the size of a turtle egg will be placed on top of the turtle nests before the excavated sand is filled back in to cover the site. The smart sensor will measure motion and temperature in the nest, with the hope of being able to determine when hatching is imminent. The smart sensor is connected to a communications tower which will send out regular reports on the activity in the nest using M2M technology. The text file reports are FTP'd to a website directly from the communications tower. |
===Smart Sensor=== | ===Smart Sensor=== | ||
| − | The Smart Sensor has a 3-axis motion sensor (accelerometer) and temperature sensor connected to a very low power microprocessor. There is also an RS485 transceiver chip which connects to the communications tower via a shielded Cat5 cable. The smart sensor can be programmed to take readings 12.5, 25, 50, 100, 200 or 400 times every second. Each reading is compared with the previous reading to determine the change in acceleration | + | The Smart Sensor has a 3-axis motion sensor (accelerometer) and temperature sensor connected to a very low power microprocessor. There is also an RS485 transceiver chip which connects to the communications tower via a shielded Cat5 cable. The smart sensor can be programmed to take readings 12.5, 25, 50, 100, 200 or 400 times every second. Each reading is compared with the previous reading to determine the change in acceleration -- or "jolt". Rather than record each jolt, the sensor counts how many readings have reached approximately 25 different magnitude levels. These magnitude levels (which we call "bins counters") are in a logarithmic scale. Each bin is the square root of 2 larger than the next. We keep count for a variable amount of time (between 1 and 6 minutes) and then start a new set record with a new set of bins. This allows us to track how much motion there was at multiple magnitudes over time. |
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| − | + | ===Communications Tower=== | |
| + | Since it is not possible to make telemetry connections under wet salty sand, the smart sensors are connected to a communications tower. The design is based around creating a custom processing mother board connected to an off-the-shelf telemetry board. The mother board has a very low power microprocessor which controls and monitors the activity of the smart sensor and controls the telemetry board. There is also a power supply, a RS485 telemetry chip and connectors for future expansion. The electronics are mounted in 3 inch PVC pipe and fittings anchored in a 5 gallon bucket filled with concrete. The concrete base and Cat 5 cable are buried in the sand. The The tower sends text reports to our web space via an FTP connection using the telemetry board once a day when the nests are not very active, and increases to 6 times a day when the nest becomes more active. Since the communications tower only makes one to 6 reports a day, The microprocessor turns the telemetry board on and off, so that it consumes no power when it is not being used. | ||
| − | + | ===Hand-Held Registration Unit=== | |
| + | A communications unit is mounted in a small hand-held unit so that it can be taken in the field when nests are excavated. This allows park service personnel to carry just the light-weight sensors and the hand-held unit to the nest sites. Later, the heavy communications towers can be brought in. The Hand-Held units have GPS capability. They are programmed to test the sensors to make sure they are functioning properly, get a GPS reading, check for a good cell connection, and get the local time and date from the cell phone network. The date, time and GPS location are sent to the sensor, so that all this information will be available to the communications tower when it eventually connected. | ||
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== Engineering == | == Engineering == | ||
== Commercial options== | == Commercial options== | ||
| + | Before proceeding, we researched other commercially available data recording systems to see if anything that would meet our requirements was available. None of the options we found were low enough power to fit our needs, and none provided the data we were hoping to collect. The closest matches we found would have required as much or almost as much custom engineering on our part to make it work, and there was no cost benefit to going that route. | ||
*[[Chuck's research on data recorders]] | *[[Chuck's research on data recorders]] | ||
===Components=== | ===Components=== | ||
Revision as of 04:13, 26 June 2014
Phase two is starting up.
People
- User:Dave -- Electrical engineering / Mechanical engineering
- User:Sam -- Project manager / Embedded Software
- User:Tom -- Engineering support
- User:Eric -- Fundraising / Community liaison
- User:Chuck -- Sea Turtle community outreach / Materials
- User:Chris -- Web Server Admin
- User:Mark -- Web design
- User:Britta -- National Park Service Biologist
Overview
The plan for Phase Two is to create about 10 communications towers and 20 smart sensors for installation in the Outer Banks of North Carolina during the Spring and Summer of 2013. When nests are discovered by park personnel, the nests are uncovered, the eggs counted, and a DNA sample is taken. At that time, a smart sensors the size of a turtle egg will be placed on top of the turtle nests before the excavated sand is filled back in to cover the site. The smart sensor will measure motion and temperature in the nest, with the hope of being able to determine when hatching is imminent. The smart sensor is connected to a communications tower which will send out regular reports on the activity in the nest using M2M technology. The text file reports are FTP'd to a website directly from the communications tower.
Smart Sensor
The Smart Sensor has a 3-axis motion sensor (accelerometer) and temperature sensor connected to a very low power microprocessor. There is also an RS485 transceiver chip which connects to the communications tower via a shielded Cat5 cable. The smart sensor can be programmed to take readings 12.5, 25, 50, 100, 200 or 400 times every second. Each reading is compared with the previous reading to determine the change in acceleration -- or "jolt". Rather than record each jolt, the sensor counts how many readings have reached approximately 25 different magnitude levels. These magnitude levels (which we call "bins counters") are in a logarithmic scale. Each bin is the square root of 2 larger than the next. We keep count for a variable amount of time (between 1 and 6 minutes) and then start a new set record with a new set of bins. This allows us to track how much motion there was at multiple magnitudes over time.
Communications Tower
Since it is not possible to make telemetry connections under wet salty sand, the smart sensors are connected to a communications tower. The design is based around creating a custom processing mother board connected to an off-the-shelf telemetry board. The mother board has a very low power microprocessor which controls and monitors the activity of the smart sensor and controls the telemetry board. There is also a power supply, a RS485 telemetry chip and connectors for future expansion. The electronics are mounted in 3 inch PVC pipe and fittings anchored in a 5 gallon bucket filled with concrete. The concrete base and Cat 5 cable are buried in the sand. The The tower sends text reports to our web space via an FTP connection using the telemetry board once a day when the nests are not very active, and increases to 6 times a day when the nest becomes more active. Since the communications tower only makes one to 6 reports a day, The microprocessor turns the telemetry board on and off, so that it consumes no power when it is not being used.
Hand-Held Registration Unit
A communications unit is mounted in a small hand-held unit so that it can be taken in the field when nests are excavated. This allows park service personnel to carry just the light-weight sensors and the hand-held unit to the nest sites. Later, the heavy communications towers can be brought in. The Hand-Held units have GPS capability. They are programmed to test the sensors to make sure they are functioning properly, get a GPS reading, check for a good cell connection, and get the local time and date from the cell phone network. The date, time and GPS location are sent to the sensor, so that all this information will be available to the communications tower when it eventually connected.
Engineering
Commercial options
Before proceeding, we researched other commercially available data recording systems to see if anything that would meet our requirements was available. None of the options we found were low enough power to fit our needs, and none provided the data we were hoping to collect. The closest matches we found would have required as much or almost as much custom engineering on our part to make it work, and there was no cost benefit to going that route.
Components
Turtle egg sensor
This would be unchanged from the phase one design that uses plastic ping-pong balls (not good ping-pong balls, but cheap plastic knock offs) and a temperature/motion sensor pre-installed on a small circuit board (Qty 1 Price=$14.95). Assembly involves cutting a small slot in a ball, putting in some silicone caulk, inserting a sensor board attached to a cable into the caulk, and then filling the rest of the ball with caulk. A ball cut in half covers the slot and makes a thorough seal with the silicone.
Mother board
We are creating two prototypes of the mother board. One will have through-hole components and the second has primarily surface-mounted parts. The through-hole hole mother board has headers for attaching a pre-fabricated processing board based on the TI MSP430 CPU and another two rows of headers for a prefabricated telemetry board. The surface-mount board only has headers for the telemetry board. The circuitry on the pre-fabricated processing board is duplicated almost exactly on the surface mount boards. Both boards are functionally equivalent and will operate identically with the same software.
By creating two versions of the mother board, we can make the design useful to more people, and ultimately help protect more turtles. The through-hole board is easy to assemble for anyone with basic electronic soldering experience (think hacker space events and high schoolers). The surface mount board is designed for mass production and is very difficult to assemble without expert soldering skills and magnification because the parts are much smaller, there are many more of them (because it does not use the prefabricated processor board) and surface mounted parts are not designed for hand assembly. The surface-mount board is therefore optimized for automated production in larger quantities. In large quantities the cost of components and assembly is competitive with the cost of just the components of the through-hole board. While the design of the surface mount board is much more complicated than the through-hole board, it solves the problem of having to find volunteer labor for assembly.
While both the telemetry and processing boards already have their own power regulators built in, but there needs to be an additional power regulator for the telemetry board on the mother board to regulate battery power down to the voltage required by the telemetry board. The power regulator for the telemetry board can be totally powered down most of the time, and then powered up when data needs to be uploaded (typically just once a day). This greatly reduces the power requirements of the unit. Depending upon how frequently data is uploaded, the units will operate for many months on a single battery charge. The surface-mount board has two power supplies, one for the telemetry board and the other for the micro-processor.
The custom circuit boards are 2.5 inches by 3.8 inches. Three of these boards can be purchased for as little as $51 plus shipping. For larger production runs the price would be much less per unit (about $5 each for a run of 100 including shipping). Other components on the board total between $15 (surface mount) to $22 (through hole). The through hole board also needs a processing board which adds about $18. The $25 savings in parts for the surface mount board is about the same as the cost of having it assembled. The total cost per board is about $40 either way.
Processing board
For the through-hole board we usea pre-assembled processing board made by Oilmex Ltd, that is based on the the ultra-low-power MSP430FR5739 processor by Texas Instruments. The MSP430-HFR5739 board has all the essential components needed. There is a header on the board for easy programming, and a connector which we can use for plugging in the cable to the turtle egg sensor. The MSP430FR5739 CPU has 16K Bytes program FRAM, 1024 Bytes SRAM, 10-bit A/D converter, 16-channel comparator with voltage reference generation and hysteresis capabilities which we can use for monitoring the battery voltage, three enhanced serial channels (capable of I2C, SPI, or UART protocols), hardware multiplier, real-time clock, five 16-bit timers, and more. The board also has power supply filtering capacitor and a 3.3V voltage regulator. There are two rows of headers for each pin of the microprocessor which we will use to plug this board into the mother board. The dimension of the board is 2.15" × 1.10". The boards cost only $18.13 qty 1 and are available from microcontrollershop.com.
The circuitry on the processing board is duplicated on our surface mount board almost exactly. The only difference is we have omitted one auxiliary button which we do not need.
Telemetry board
We plan on using plug in Terminus boards made by Janus. The Janus GSM865CF v1.1 GSM/GPRS Modem with GPS works with AT&T and T-mobile. For Verizon we can use the CDMA864CF v3.0. The boards are interchangeable and will plug into our motherboard. The cost is roughly $140 qty 1 and are from the manufacturer, Janus.
Other components
The only other components necessary are the cable and connector for the turtle egg sensor (a couple of bucks at most), an antenna for the telemetry board (GSM and GPS), which costs about $20 (perhaps more if reception is a problem). The units should operate for roughly 4 months running on 4 or 8 low self-discharge NiMH Batteries. The batteries and holder (TBD) cost about $25. Also, anyone creating these devices will need the hardware necessary for programming the microprocessor (more about this later).
The hardware cost of the electronics is about $250 per unit after start up expenses, and not counting telephony charges, taxes and shipping.