As I tell Bart that bees are very sensitive to vibrations on the waxcomb, and that this is one of their means of communication in the hive, Bart brings up to introduce an acellerometer to measure the vibrations of the wax comb in 3 axis. We will research this asap.
triple access accelerometer + compass
ADXL377 - High-G Triple-Axis Accelerometer (+-200g Analog Out)
⇒ the measurements of an accelerometer are problaby not detailed enough to sence and aggregate comb vibrations - which are very small vibrations. We should think more into the direction of a seismograph.
A laser Doppler vibrometer (LDV) is a scientific instrument that is used to make non-contact vibration measurements of a surface. The laser beam from the LDV is directed at the surface of interest, and the vibration amplitude and frequency are extracted from the Doppler shift of the reflected laser beam frequency due to the motion of the surface. The output of an LDV is generally a continuous analog voltage that is directly proportional to the target velocity component along the direction of the laser beam.
Some advantages of an LDV over similar measurement devices such as an accelerometer are that the LDV can be directed at targets that are difficult to access, or that may be too small or too hot to attach a physical transducer. Also, the LDV makes the vibration measurement without mass-loading the target, which is especially important for MEMS devices.
Behaviour-locked signal analysis reveals weak 200-300Hz Comb Vibration during the Honeybee Waggle Dance
27/05/2014: Bart De Boer
Er zit goede vooruitgang in de voorbereidingen aan de VUB, maar ik kan me voorstellen dat (gezien het feit dat we al laat in het seizoen zijn) we misschien pas volgend jaar hier echt metingen kunnen doen. Daarmee vroeg ik me af of we (op proef) nog een extra sensor in een van jouw bijenkasten konden toevoegen: ik heb eens gekeken naar trillingssensoren, en heb een goede gevonden voor rond de 70 euro, die via USB werkt. De trillingssensor waar ik het over heb is van Phidgets, verkrijgbaar onder andere bij: http://www.eztronics.nl/webshop2/catalog/Phidgets/PhidgetsSensors?product_id=222
Voor zover ik het kan inschatten is die aardig gevoelig voor trillingen in het frequentiegebied dat mij zou interesseren, maar we komen er alleen maar achter door het uit te proberen. Zo'n laseropstelling (interferometer, neem ik aan) is natuurlijk veel gevoeliger, maar ten eerste onbetaalbaar in dit stadium en ten tweede te onderhoudsgevoelig voor langdurig gebruik buiten.
Ik kan misschien direct twee van die sensoren bestellen. Dan kunnen we er een in de raat inbouwen en een houden we dan zelf, zodat we kunnen oefenen met het programmeren ervan.
The PhidgetSpatial Precision 0/0/3 (1043) is a 3-axis accelerometer that can measure up to ±8 g of acceleration in each axis, and has high precision when measuring acceleration within ±2 g. The transition from high precision to low precision mode and back is completely seamless and automatic.
The 1043 could be used to:
1. Sense tilt angle in remotely controlled vehicles
2. Capture motion input data for research purposes
3. Detect the presence of nearby movement or vibration
Specifications - http://www.phidgets.com/docs/1043_User_Guide
• Acceleration Measurement Max: ± 8 g
• Acceleration Measurement High Resolution: ± 2 g
• Acceleration Measurement High Resolution: 76.3 μg
• Accelerometer High Resolution White Noise σ: 300 μg
• Accelerometer Minimum Drift σ: 37 μg
• Accelerometer Optimal Averaging Period: 103 s
• Current Consumption Max: 35 mA
• Sampling Speed Min/Max: 1 s/sample - 1 ms/sample
• Sampling Speed Min/Max (Webservice): 1 s/sample - 16 ms/sample
• Analog to Digital Converter Resolution 16 bit
“Years after von Frisch interpreted the symbolism of the dances, Wenner and Esch independently found that dancing bees make sounds during their waggling run. Both men suggested that the sounds might help the dancer attract an audience in the dark nest. Many researchersdoubted this premise becausethey thought bees could not hear airborne sounds. Still, the notion was not ignored altogether. Many insects, including bees, are quite sensitive to vibrations. Hence, some investigators speculated that the sounds the foragers produced could vibrate the combs under their feet as they danced. The comb vibrations might then advertise the dance to those bees who could not otherwise see the forager.
One of us (Kirchner), together with Axel Michelsen of Odense University in Denmark, answered part of this question several years ago. In their experiments, Michelsen and Kirchner aimed a laser beam at the comb near a dancing bee to determine whether or not the dance sounds generated vibrations in the comb. Surface vibrations, if any occurred, would cause minute changes in the light refiected from the comb. In this way, it was possible to measure the vibrations without touching the comb and possibly triggering additional tremors. These measurements revealed that dancing bees do not rattle the comb but that their audience does. The dance attenderssometimes emit a short squeak by pressing their thoraxes against the comb. This action vibrates the comb enough so that the dancing bee stops her movements. She then doles out small samples of the food she has collected so that her audience knows not only the direction and distance to the feeding site but how the food smells and tastes as well.”
I also added a SHT15 t° and humidity sensor into the beehive. https://www.sparkfun.com/products/8257
This is a simple breakout board for the SHT15 humidity sensor from Sensirion. The SHT15 digital humidity and temperature sensor is fully calibrated and offers high precision and excellent long-term stability at low cost. The digital CMOSens Technology integrates two sensors and readout circuitry on one single chip.
Why t° and hu are so important in the hive: The average temperature in the beehive is between 32-35°C. Honeybees have the ability to regulate the temperature of their nest throughout the year. If it is cold, bees raise the temperature within the hive by huddling together to keep warm and vibrating their wing muscles to generate heat. If it is hot, they lower it by fanning their wings to circulate air through the hive. If it is really hot, they collect water for evaporative cooling. Droplets of water are placed inside the hive, then the bees stand in a line facing the hive entrance fanning their wings creating air currents that evaporate the water, thus cooling the hive. Whenever fanners are at the entrance, there are many inside the hive doing similar fanning to control the hive temperature.
temperature in the hive
⇒ check also what A. Warré has to say about temperature, humidity and ventilation in the beehive. A Warre hive has a special ventilation approach.
The environmental data (with timestamp) of the garden are aggregated with the WASP (smart agriculture) module from Libelium.
Screenshot of the data visualisation of the temperature/humidity sensor in the Warré1-hive (intelligent-beehive).
The temperature was only in the 20 degrees. After changing the sensor from the upper box (that was filled with honey) tot the box below, the temperature immediately raised up to 35 degrees constant.
This makes clear we need temperature sensors spread over the average totality of the behive, at least more than 1 in every box!