In June team AuTomatoes won the second edition of Wageningen University’s Autonomous Greenhouse Challenge. There was no discussion about the team’s win, they scored highest on all three grading criteria, making them the absolute winner. In their strategy the team applied the principles of Plant Empowerment, to realize a balanced and empowered crop. Thus, the plant and its balances were at the center of all the team’s algorithms. So how did they do this? This article explains all about the energy balance and how team AuTomatoes kept it in balance at all times.
The energy balance is the balance between the energy flow towards (input) and from (output) the plant. Since plants can’t produce heat of their own, the energy balance consists exclusively of external energy flows, i.e. short wave radiation from sunlight or lighting, long wave heat emission, convective energy transferred by moving air, and evaporation energy.
During their mission to grow the biggest amount of good quality tomatoes, team AuTomatoes made use of a combination of sensors to uncover the vertical temperature profile and available amount of light at crop level. For this they made use of a PAR sensor. In addition, they installed a Thermoview camera, which takes thermographic pictures of the crop that show the differences in temperature. With this information the team could optimize the usage of screens and heating to support the crop’s energy balance in the best way possible.
Next to these existing sensors team AuTomatoes also developed so-called soft sensors, which can be used to for example calculate the PAR level in the greenhouse. Based on the outside PAR, measured by a PAR sensor, the light transmittance of the canopy and screen, and use of assimilation lighting, the software calculates the available PAR light at crop level inside the greenhouse. This of course can also be measured by a PAR sensor. However, these measurements can sometimes vary, e.g. because of shading. The soft sensors level out these differences, and herewith complement the PAR sensor. In addition, the measurements of the PAR sensor can be used to check the PAR level according to the software, to avoid mistakes. Together, the PAR sensor and soft sensors provide the right data to control the PAR level in the greenhouse.
In addition to the soft sensors, team AuTomatoes also developed the Ventilation Optimization Control, to benefit the crop’s energy balance. The algorithm controls the vent positions according to the desired setpoints for temperature and humidity. With this control the team managed to maximize photosynthesis, while using a minimal amount of resources.
Do you want to know more about the soft sensors and Ventilation Optimization Control? Or are you curious about other developed solutions for growers, and the Data Driven Growing strategy executed by team AuTomatoes? More will be explained in later articles and during a webinar on September 2nd.