This test is an interesting case because it both the natural light compensation abilities of the system and the ability of the system to recover from transmission errors. The prototype system is designed with very basic transmission error checking which allows for a small number of erroneous transmissions to propagate through the system. Figure 5-7 shows the fluorescent lamp settings transmitted to the units as recorded by the building server. It is important to note that the settings as plotted are the values transmitted by the zone manager during the test, not directly the values calculated by the zone manager. As is evident from this plot, there are false settings requests transmitted that are outside the scope of feasible control commands (0 to 100). As the errors are on the high end of the control spectrum, the lamps respond by switching to 100 percent of their output which vastly exceeds the required light level. In each case the control system overshoots on its response in the next query but then quickly returns to tracking the requisite light level. A corresponding jump in sensor reading, as shown in Figure 5-8, matches the lamp setting increase most prominently in the closest sensor but smaller responses are visible in the neighboring sensors as well. This overshoot response is due to the system using the internally recorded previous setting of the lamps to calculate the current natural light contribution to the space. As the zone manager bases this calculation on the correct previous setting for the lamps and not the erroneous transmitted one, it perceives some of the artificial light contribution as natural light and therefore sets the lamps too low on the next iteration. Because the required past information for the system only goes back one time step, the system is able to quickly recover to the proper settings. While this set of errors is specific to this implementation and test run, the ability of the system to be resilient to error is important as even a commercial grade implementation cannot be entirely free of transmission and execution errors. In this test, the overall trend toward decrease in energy use and decrease in sensor readings is more pronounced than in Test A because the sensors are oriented to capture more of the daylight contribution. As the sunlight contribution represents a larger portion of the total light available at the start of this test as compared to Test A, the sensor readings show a larger decrease over the course of this experiment as sunlight is less visible to the sensor and fluorescent light contributes more heavily to the total
This test is an interesting case because it both the natural light compensation abilities of the system and the ability of the system to recover from transmission errors. The prototype system is designed with very basic transmission error checking which allows for a small number of erroneous transmissions to propagate through the system. Figure 5-7 shows the fluorescent lamp settings transmitted to the units as recorded by the building server. It is important to note that the settings as plotted are the values transmitted by the zone manager during the test, not directly the values calculated by the zone manager. As is evident from this plot, there are false settings requests transmitted that are outside the scope of feasible control commands (0 to 100). As the errors are on the high end of the control spectrum, the lamps respond by switching to 100 percent of their output which vastly exceeds the required light level. In each case the control system overshoots on its response in the next query but then quickly returns to tracking the requisite light level. A corresponding jump in sensor reading, as shown in Figure 5-8, matches the lamp setting increase most prominently in the closest sensor but smaller responses are visible in the neighboring sensors as well. This overshoot response is due to the system using the internally recorded previous setting of the lamps to calculate the current natural light contribution to the space. As the zone manager bases this calculation on the correct previous setting for the lamps and not the erroneous transmitted one, it perceives some of the artificial light contribution as natural light and therefore sets the lamps too low on the next iteration. Because the required past information for the system only goes back one time step, the system is able to quickly recover to the proper settings. While this set of errors is specific to this implementation and test run, the ability of the system to be resilient to error is important as even a commercial grade implementation cannot be entirely free of transmission and execution errors. In this test, the overall trend toward decrease in energy use and decrease in sensor readings is more pronounced than in Test A because the sensors are oriented to capture more of the daylight contribution. As the sunlight contribution represents a larger portion of the total light available at the start of this test as compared to Test A, the sensor readings show a larger decrease over the course of this experiment as sunlight is less visible to the sensor and fluorescent light contributes more heavily to the total