Artificial light is an integral part of life. Without it, daily functions would be restricted to the hours of natural light provided by the sun. With 24-hour access to artificial light, the workday can turn into the “work night.” Although artificial light is extremely beneficial, it also has its downfalls. One main disadvantage is the vast amounts of energy consumption. Even though artificial light is needed, not every circumstance calls for blinding amounts of light when there is perfectly good natural light right outside the window. However, many artificial lights only have one setting which leads to two options: total darkness or full on blinding light. This can lead to a huge waste of energy. Flipping a light switch or walking down a well-lit hallway are both everyday luxuries that are often taken for granted. The easy access of artificial light has resulted in abuse of it as a resource. Figure 1 shows the potential savings by using dimmers.
This energy could be conserved if there was a system that measured the amount of light present and then only supplied enough artificial light that is needed. For example, imagine if during the peak hours of sunlight, artificial lights would dim automatically to adjust for an increase in sunlight. This would decrease the amount of energy use and, ultimately, save money. As the sun begins to set, the artificial lights in a room would compensate for the loss of natural light to keep a constant and desired amount of light in a room. The idea of auto dimming has many benefits other than saving energy and money, like extending the life of a light bulb, creating a more productive atmosphere, and a healthier life in general.
The reason why this product is so valuable is that it can reinvent the way people not only light their homes, but also office buildings, schools, and other public spaces. In public spaces, people don’t usually pay much attention to the status of the lights and often forget to turn them off when they leave a room. Along with over use of artificial light when people are in the room, there is even more wasted energy of when people leave lights on in an empty room. This product will not only have auto dimming but also a controller that can dictate when lights should turn off and on at the beginning and end of a work day.
This auto dimming lighting system uses a sensor that detects the brightness in a room, which then transmit a signal to the artificial light, which also has a sensor attached to it. The sensor will then tell the controller to dim or brighten the artificial light according to the amount of natural light already present in the room. For example, at night the amount of artificial light will be the highest level since there is no sunlight available. As the sun starts to rise, the amount of artificial light starts to decrease since the amount of light already present starts to increase due to the increase of sunlight. Unlike a timer system which would just have the amount of artificial light increasing and then decreasing with respect to time, a process controller would also allow for the total amount of light to stay constant even on cloudy days. A similar control process is used in devices such as IPhone and IPad in order to adjust the brightness of the screen in response to the lighting of the surrounding environment.
The controlled variable is the amount of light in the room. To determine the ranges of this variable, the consumer would do a calibration based on their preference of what the desired amount of light in the room should be. This would include light in the early morning, mid-morning, midday afternoon, evening and night. The control of this variable is crucial to the operation of this product because if the light is not controlled, the dimmer will not work properly and provide adequate amounts of light. However, since lights can be controlled manually by a person flipping a switch, controlling the amount of light is not crucial to the original function of the light.
The manipulated variable of this process is the amount of artificial light in the room. However, it would only be the overhead artificial light sources. Other sources of artificial light, like floor lamps, flashlights, and desk lamp would not be considered manipulated variables because they are used for additional light needed for specific locations. These would be considered disturbance variables since when a lamp is turned on, the ceiling lights or recessed lighting would adjust based on the amount of light in the room. Other disturbance variables are the amount of light coming into the room and where it shines. For example, if curtains are suddenly closed, the system needs to respond quickly so that the person in the room is not left in the dark. It is more practical for the artificial light to be the manipulated variable than the sunlight since it would be harder to control the amount of sunlight coming into the room with curtains or mirrors.
These disturbance variables would all be controlled by the same manipulated variable, the amount of artificial light, by way of a feedback loop. A feedback loop is when the output of the system is compared to a known or ideal value. The difference between the desired amount of light and the actual amount of light in the room is then turned into an error signal that is transmitted to a controller. The controller would then adjust the amount of artificial light supplied to the room based on this error. Figure 2 shows how all the variables interact.
Installing this controller is better for the environment and the user’s wallet because it ensures the minimum amount of electricity, and thus energy, is used throughout the day. The video below demonstrates how the auto dimming lights can be used in daily life. As the curtain rises, the artificial light in the room begins to dim. However, the total light in the room remains the same. Thousands of watts of energy are unnecessarily wasted because the availability of natural light that is neglected. And God said let there be light, NATURAL light. So use it, dang it!
From this blog post, one understands that a lot of energy can be consumed when artificial lighting is used. Therefore, dimmer/sensors can be used to reduce the amount of energy consumed to produce artificial light when it is not necessary. Sensors detect the brightness of a room, and then that information is transmitted to the artificial light as a signal. The main goal of the sensors is to adjust the brightness of the lights in response to the lighting of the surrounding. The artificial light will adjust to its setpoint. According to Figure 1, dimmers and sensors can reduce up to 60% of potential lighting used, saving consumers money. Users currently use this product whenever they want to reduce the cost of their electricity bill or become more environmentally friendly. Big companies and universities already tend to use these products since they are user friendly to the population they serve and are cost-efficient for the entire domain.
It makes sense that the controlled variable is the amount of light in the room since it is being controlled. The manipulated variable would be the light sources that are connected to the sensor. This is the most optimal manipulated variable in the room since the other variables affecting the brightness of the room are more difficult to control. It would be more arduous to use a sensor in order to signal to a process to lift up a curtain or to turn on just one lamp than control the entire artificial lighting system. As it is with every process, there have to be variables that disrupt the process from reaching the setpoint. Disturbance variables can include lamps that are not connected to the artificial lighting and are draining energy from going to the artificial lighting. The blog post does not mention that any additional electrical usage can cause this disturbance variable as well. If the power goes out or if the TV in the room is turned on, this might channel less energy to the artificial lighting if everything is occurring at the same time, and there is no generator. Manual light changes can also be disturbances, especially if a curtain is pulled open or closed.
The controller type that would be most appropriate for this product would be the PID controller since it allows for fast response to sudden changes, eliminates oscillations, increases control, and improves stability. Developers of this product can tune the controller of the process by using PID Tuning Software, such as Simulink PID Controller Training, or by using the Ziegler-Nichols tuning method. Using the Ziegler-Nichols tuning method allows for experiments to take place on a closed loop which allows for tuning while the controller is on. By doing this, developers could see how much brightness is exhibited as the controller is adjusted.
Artificial light is probably one the most important yet most underrated inventions created, and is rarely given the recognition it deserves. By becoming so essential and widespread in present day, it is often taken for granted and abused. The article raises the excellent point that current light models can be very inefficient in both design and application. Most light switches only include one setting, and thus never take into account for the free light supplied by the sun. It is also extremely common for people to leave switches on when not in use: both of these factors result in a large amount of energy being wasted that is often no thought about.
The application proposed by this article makes perfect sense and would be extremely useful. Artificial light is rarely needed during the daytime when there are windows properly placed in the room. By using a sensor to combine both of these sources, less energy will theoretically be spent. This could definitely be applied to common light systems all over the world. The authors also did a very good job of citing how similar technology to this is used by millions in their smart phones to adjust the screen brightness.
The control aspect of this also makes sense: light sensors are a very common and accurate technology, and light dimming is also a widely used. The selected manipulated and controlled variables are straight forward and are well considered with the controller proposition. The disturbance variables of extra light sources in the room was great aspect to point out, but should be taken into account with ease with the current model of the controller. While the proposed controller should properly use natural light, it does not take into account for people forgetting to turn off the lights, which probably accounts for a larger amount of wasted energy. I suggest that a motion sensor is also implemented into this system that could send a signal to turn off the lights if there has been no one occupying the room. Another aspect to consider is how much energy all of these components will consume, and ensure that the amount of electricity they save in comparison to the amount light being saved will be all of the production and installation costs.
A closed loop system is essential to this controller due to the need for a feedback system. The current state of lighting systems is open loop with no consideration for outside factors. The calibration procedure explained in the article would be a great way to properly tune the controller parameters to achieve the desired lighting conditions. There needs to be a reference for the desired lighting in order to find the error difference. Further tuning would need to be completed in order to ensure that the light setting is achieved as quickly and smoothly as possible. This will most likely be achieved by the parameters set and the quality of sensors/controllers being implemented.
I love the topic that you all chose! It is definitely relevant to the idea of reducing energy consumption. I also really like the first figure that you placed in the post, as it allowed me to really understand the potential energy savings of this idea. However, if possible, I would be interested to see the energy savings compared to or normalized by the production and implementation costs. From the prospect of dimmer/sensor product commercialization, this seems as thought it would be the limiting constraint.
Next, I think it is logical that you all chose to make amount of sunlight your controlled variable, but I’d be interested to know if you considered other potential variables that you could control to reach the same desired output (e.g. electricity consumption). Furthermore, I think about one design constraint that I would really like to see you all speak towards in future posts–the incidence angle of sunlight. As you are aware, the way in which light hits through a window and disperses through a room is highly variable. This can even be seen in the video that you all posted. As the blind goes up, you can see a noticeable gradient of light throughout the room even though it may still be lighted by the light by a little bit. Additionally, as we have learned in our process control class, we sometime don’t like harsh incident angles that get into our eyes, so how would your system be made customizable so that the user can be able to adjust for this?
Lastly, many companies are beginning to explore home automation and integration of furniture, appliances, and general utilities, to optimize the energy efficiency of homes. Instead of seeing other lighting as a disturbance, you might be able to consider them as a part of your control system. This would be assuming that lamps and other light sources will be on the “cloud” which is not an erroneous idea within the next 10 years. If you are interested in exploring this, check out this article: https://www.irjet.net/archives/V2/i3/Irjet-v2i3317.pdf
The motivation for the auto dimming light system is not only sensible but economically and energy favorable. If the auto dimming light system was established an introduced world wide, a small but large fraction of the world’s energy consumption would decrease. Everyone knows that natural light trumps artificial light!
As stated, the control variable will be the amount of light within the room. The amount of light can be represented as brightness. Furthermore the manipulated variable is the amount of artificial light. I believe the way you could manipulate the brightness of the artificial light is by explicitly manipulating the amount of electrical current to the light bulb, or manipulating the amount of resistance within the electrical line.
A recommendation may be to utilize multiple sensors that are spread through out the room in which the auto dimming light system operates. The multiple sensors will pick up different levels of brightness, indicating there are spatial differences with respect to the brightness of the light. This is analogous to a CSTR being “un-mixed.” To avoid this problem, an average brightness can be calculated amongst the sensors in which sends the signal to the comparator. It is important to have enough sensors to have representative sampling.
Something to consider is multiple set point change throughout the day. A user should be able to change the set point of the control variable based upon his/her schedule. For example, why would the lights be on in the kitchen in the middle of the day while you are at work? Not only do you want to account for the users schedule, but the lower limit of operation for the system. What I mean by this is, if the amount of natural light in the room is extremely close to the set point, however is not exact, what the point of even using lights to reach that set point. It’s a waste of energy to have the lights on just so barely. The system should include some sort of allowable offset that determines if the lights should even be on.
The disturbance variable will be the additional light entering the room in which the auto dimming light system is being used. Here, the disturbance can not be counteracted however utilized to reach the set point. The disturbance is working in your favor. A foreseeable problem is if the disturbance is causing a higher brightness than desired. In this case the system should just be shut off.
When determining the control system utilized within the experiment, you might want to consider the amount of noise within your system. If you foresee a lot of noise coming from your sensors, you should only utilize PI control. Additionally, there will always be some sort of disturbance variable affecting the system. In order to dampen these perturbations, a FF control system should be introduced.
I stayed with my friend at Temple University a few years ago in their new high rise dorm and in every single hallway between apartments, they had implemented this type of auto dimming and it worked very well. The only difference was that their system was controlled by motion and the lights were turned completely off except for the emergency LED lights. Typically, students do not spend an incredible amount of time in the hallways and it doesn’t make sense to have the hallways brightly lit at all times. The motion sensors attached to the system had a good response time so that when you did walk down the hall, you were never in the dark. Additionally, at the end of each hall there were large windows with a view of the city to let in lots of ambient light. I think this was well executed and I think that it should be more widely implemented in more buildings.
I do have a concern in terms of how these would actually reduce the amount of energy used. To my knowledge, the dimmer itself is a voltage divider circuit which divides the amount of electricity that flows through the lamp itself or the internal resistance of the dimmer. As the light “dims” the power that would be flowing through the lamp now flows through the internal resistance and is still used electricity. My concern would be that if lights were only being dimmed, that they would consume no less electricity than if the lights were on the entire time. Additionally, I would wonder if because the people with these systems would forget to monitor the status of their other lamps (desk or reading) because they were used to the light being controlled automatically and the thought may not cross their mind to check. This may happen similarly to how sometimes manual toilets do not get flushed because most toilets have automatic flushing devices and the user assumes it will take care of it. By no means do I wish to bash the idea, I would just be interested to hear how this change in control system for house lighting would incorporate potential new disturbance variables.