Arduino-‐Based Control System for Measuring Ammonia in Air Using Condi8onally-‐deployed Diffusive Samplers
Jay Ham, Chris-na Williams, and Kira Shonkwiler
Contact Information: Jay Ham, Professor, Department of Soil and Crop Sciences, Colorado State University. [email protected].
Objec8ve
Develop a robo-c condi-onal sampler for Radiello diffusive NH3 samplers so that cartridges are only exposed to air under user-‐defined weather condi-ons (i.e., specific wind direc-ons and wind speeds). The control system extends the diffusive sampler into the air using a linear actuator when the wind is coming from the direc-on of the source. Otherwise, the system retracts the sampler into a sealed tube (no sampling). The instrument is low-‐cost and open source so a large number of self-‐fabricated samplers can be made and deployed by poten-al users (e.g., researchers, consultants, regulators, ci-zen scien-sts, etc.).
Design Elements
§ Weather Sensors ü Anemometer and Wind Vane ü Temperature and Humidity ü Tipping Bucket Rain Gauge
§ Datalogger and Control System ü Arduino ü Shields for Arduino ü Suppor-ng Circuits
§ Robo8c Actuators ü Micro Linear Actuators ü Acrylic Tubes ü Hall Effect Transducers (for sensing posi-on)
§ Radiello Ammonia Samplers § Solar Power, BaHery, and Enclosure § Wireless Communica8on (op8onal)
Field Tes8ng
All field tes-ng was conducted at large caUle feedlots in Colorado, USA. Typically the Radiello samplers were replaced every two weeks. The NH3 absorbed by the cartridges was determined by ion chromatography. The mass of N on the sampler and the dura-on of exposure (total min.) was used to calculate the NH3 ppb in air.
Got Beef ? Got Ammonia !
Vola-liza-on from livestock waste is the largest emission source of NH3.
Fig. 6. Ammonia concentra-ons measured near a caUle feedlot with the Arduino based system (wireless network version). Weather condi-ons met the wind speed and sampling criteria 25% of the -me ( samplers were typically exposed for a total of 3.5 days during a 14-‐day sampling period).
Acknowledgments The project was supported by grants from USDA, EPA, and NRCS.
What’s Next
• Develop a custom Arduino shield for the air sampling applica-on.
• Publish design, schema-cs, bill of materials, sobware, and other fabrica-on specifics for open source sharing on website.
• Compare sampler to other research grade techniques.
• Deploying systems at mul-ple dairies and caUle feedlots for long-‐term sampling, and use data to es-mate NH3 emissions and NH3 “ hot spots” using inverse modeling.
Objectives
Sampling loca-ons near a 25,000 head beef feedlot.
Fig. 1. Independent sta-on. NH3 samplers (blue cylinders) were aUached to linear actuators mounted inside acrylic tubes. When the actuator was extended the exposed cartridge protruded out the boUom of the enclosure – when retracted, the cartridge was sealed.
Hardware Arduino Results
H11I-‐1286
Independent Sta8ons: Each sampling node has its own sensors and control system -‐ makes sampling decisions independent of other nodes. Networked Sta8ons: Sampling nodes are linked via Xbee wireless modules (Digi Interna-onal), a central base sta-on makes sampling decisions – all sampling loca-ons deploy or retract simultaneously (synop-c sampling).
Fig. 2a. Tube assembly. Miniature linear actuators (Firgelli Technologies, 50 mm stroke length) were controlled by pulse width modula-on. A disk with a foam pad was aUached to the boUom of the Radiello sampler to seal the tube when retracted.
Fig. 2b. Hall effect transducers were used to sense the posi-on of the actuator shab. Data were logged by the Arduino to determine the total number of minutes deployed over a two week period.
Hall Effect Sensor
Magnet
``
Linear Actcuator
Acrylic Tube
Cap
Spacer
Vertical Adapter
Radiello Diffusive Sampler
Foam
Acrylic Disc
Hall Effect Sensor
Control Cable
Spacer
Clevis
Clevis
PlungerMagnet
Hall Effect Cable Actuator: Firgelli Tech., L12-‐50-‐210-‐6-‐R Hall Sensor: Cherry Corp., MP101301 NH3 Sampler: Sigma Aldrich, RAD168,
RAD1201, RAD122
1. Arduino Uno
2. Arduino wireless shield with Xbee module
3. Protoshield: actuator and hall sensor interface
Fig. 3. Arduino based control system for wireless sensor network. These nodes receive informa-on to deploy or retract via a wireless signal from a central base sta-on. The base sta-on has the meteorological sensors and data logging capability.
Fig. 4. Arduino datalogger shield for the independent sta-ons (base PCB by Adafruit Industries). It replaces the wireless shield (middle layer, 2) of the shield stack in the upper photo. Once customized and added to the Arduino and protoboard, the 3-‐layer module is a self contained datalogger and control system that reads: 1) wind speed and direc-on (Nova Lynx, 200-‐WS-‐02F), air temperature and humidity (Sensitron SH15), and precipita-on. These loggers use the 5-‐min wind vector to deploy or retract the NH3 samplers. All data are stored on a SD card. Sobware and schema-cs for the system are available on github. hHps://github.com/jaymham/air_sampler_ind
y = 0.941x + 0.2961R² = 0.9949
0
2
4
6
8
10
12
0 2 4 6 8 10 12
Met One
Ane
mom
eter + Cam
pebe
ll CR
1000
Nova Lynx Anemometer + Arduino
Wind Speed (m/s) Comparison
Fig. 5. Comparison of 5-‐min average wind speeds measured by a Met One 034B (upper) connected to Campbell Scien-fic CR1000 datalogger vs. a Nova Lynx 200-‐WS-‐02F (lower) connected to an Arduino Uno.
Feedlot 25,000 Head
700 m
North
South
West Lot
Base Pasture
Prevailing Wind
3834551
This project was supported by Agriculture and Food Research Ini-a-ve Compe--ve Grant no. 2010-‐65112-‐20508 from the USDA Na-onal Ins-tute of Food and Agriculture.
Cost: The bill of materials for a complete independent sta-on (Fig. 1) is $1000 (includes mast/tripod, baUeries, solar panels, etc).
Top Related