Linear ramps
Traditionally, the Priva Compass has used linear ramps. This means that when the zone is in a period ramp, the temperature changes at a constant rate. The chart below shows an example of that. Based on the the settings in the table. the heating and cooling temperature would start to ramp up from the period 2 temperatures to the period 1 temperatures at 6:00 and be finished 2 hours later at 8:00. The temperatures would remain at that setting until the start of period 2 at 18:00. They would then start ramping back down and be at the period 2 temperatures by 7:30.
Period 1 | Period 2 | |
start time | 6:00 | 18:00 |
period ramp time | 2:00 | 2:00 |
cooling temperature | 24.0 ° C | 22.0 ° C |
heating temperature | 21.0 ° C | 19.0 ° C |
Non linear ramps
In Compass release 120 (available Fall 2023), we are introducing two new options for the period control. The first new option is called non linear ramps. This option can be set per zone in Strategy -> Configuration screen.
Using the same period settings that we had in the previous example, we can see a change in the graphic where we are transitioning into and out of our periods. As we transition into period 1, the rate of temperature change starts slowly and then starts to change more quickly. Once we get closer to the new desired temperature the rate of change will slow down again until we reach our new desired heating and cooling temperatures.
The actual calculation for the rate of change is based on a trigonometric sine wave calculation.
The beginning of the ramp corresponds to the one peak of the sine wave and the end of the ramp corresponds to the other peak of the sine wave. The temperature transition will follow this curve.
Why would you consider using this type of control?
This benefit of this type of control is that it gives smoother transition going from one period to another which can improve the control of the heating and cooling systems.
Gradient curve
The third option for period control is called the gradient curve. This option completely changes how the periods work. Instead of setting temperatures that you want the greenhouse to maintain for a period of time, you can now set individual time points along with the temperatures you want the system to be at for that specific point in time. The computer will take that data and calculate all the intermediate temperatures in between those points using the sine wave calculation as described above. This type of control is called a gradient curve and can be set in Strategy -> Configuration screen.
How does this work? For instance with the settings below, we have three periods. The start times of the period is actually the point in time that we want our temperatures to be at a specific value. We see that
- At 6:00, we want the cooling temperature to be at 21° C and the heating temperature to be at 19 ° C.
- At noon, we want the cooling temperature to be at 23 ° C and the heating temperature to be at 21 ° C.
- At 20:00, we want the cooling temperature to be back at 21 ° C and the heating temperature to be back at 19 ° C.
Period 1 | Period 2 | Period 3 | |
start time | 6:00 | 12:00 | 20:00 |
cooling temperature | 21.0 ° C | 23.0 ° C | 21.0 ° C |
heating temperature | 19.0 ° C | 21.0 ° C | 19.0 ° C |
The computer will adjust the heating and cooling temperatures so that it is at the correct temperatures at the specific times provided. It will use the sine wave calculation to constantly adjust the temperature between those times.
Since the Compass has up to four periods in a day, you can set up to four points in time over a 24 hour day.
Why would you consider using this type of control?
Recognizing that nature is the normal environment for plants, this allows the grower to better mimic what naturally happens with plants. In the example above, we are mimicking a constant change in temperature over the course of the day with a more rapid rise in temperature in the morning and a slower reduction of temperature in the afternoon. This acknowledges that the natural environment is where plants thrive and empowers growers to closely replicate the inherent patterns and processes that occur in the plant's native habitat. In the provided example, we are simulating a morning temperature increase, and a gradual temperature decline in the afternoon. We are maintaining a consistent temperature throughout the night.
Will these only work for temperatures?
The ramps are integral components of the period control system, and they control not only desired heating, cooling, local and soil temperatures but also regulate humidity levels, as well as set minimum and maximum values for water temperatures and vent positions. These parameters are synchronized with the same curve, ensuring a cohesive and harmonious control system.
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