Aura

Background

In our initial comprehensive survey for need-finding in Home automation systems and products, a lot of users emphasized the necessity of reliable smart lighting systems.

Problem Space

We conducted another survey to understand user complaints about existing smart lighting systems. The majority of the users reported that they weren’t satisfied with the current products (Philips, Syska, and Wipro). Common complaints included –

• Motion is needed to keep lights on: Lights turn off if no motion is detected in the room for a given amount of time.
• Each light is independent: Each light has its own sensor, and the range of the sensor is limited. If there are multiple lights in a room, they are not in sync.
• No consideration of ambient light: The lights (local brands) operate without considering ambient light intensity. Lights will turn on when a person walks in even when plenty of natural light is already present.
• Sensors detect pets: Due to the poor placement of sensors, they also detect the motion of pets and treat it the same as a person. This leads to unnecessary consumption of electricity.

These drawbacks limit the application of the existing systems to locations where people spend only a brief amount of time like staircases, hallways, garages, etc.

Solution Space

We were exploring the concepts of mechatronics and IoT to decipher the problem. However, we had this eureka moment in our IMOR class, when we were learning about the counting principles. 

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Architecture

There are 5 main components of the system – A microcontroller, Wi-Fi module, PIR sensors, LDR’s, and electrical relays. All components except the sensors are placed inside the walls and are connected by wires through the home’s wiring ducts. The PIR sensors can be freely placed at optimum locations to detect human activity accurately. Sensors detect human activity and ambient light, relays operate the lights, the Wi-Fi module connects the system to smartphones, and the microcontroller ties it all together with algorithms and logic. 

Logic

The basic principle was to count the number of people entering and exiting the room instead of actively detecting human presence. This was achieved by a system of sequential sensor activation. Two sensors placed at optimal locations near the entrance to the room were used to detect incoming and outgoing people. Sensor 1 was placed on the outer side and Sensor 2 on the inside. If the sensors are activated in sequence 1-2, a person has entered the room, and if 2-1, a person has exited. This count is retained in memory. The delay between two count registrations is customizable, we kept it 1 sec in testing. As long as one person or more are present in the room, the lights stay on. The moment the count returns to zero, the lights turn off. The counting method overcomes two problems faced by standard PIR light bulbs. The lights do not turn off after a period of non-motion, and the range of the sensor is not limited by the placement of the bulb.

The algorithm can be modified to accommodate the different conditions posed by rooms with multiple entry/exit points.The PIR sensors are coupled with an LDR to measure the ambient light in the room. The lights will turn ON only after the ambient light falls below a customizable threshold. 

The Wi-Fi module connects the system to the users’ smartphones. Users’ can switch the system between automatic or manual operating modes. When on manual, users can control individual lights in the room from their phones.

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The sensor mount

The design of the sensor holder is also crucial. It allows the sensors to be easily mounted on any surface in any orientation, which enables optimal placement, even in the various conditions of each home. The mount also maximizes the reach of the sensor while keeping it accurate. The mount can be made from different materials with different colors to suit each home’s interior and décor. 

Future scope

Elimination of switchboards: Working closely with architects, the system can be designed to eliminate the need for a switchboard. All lights will be controlled by the system or through the user’s phone.

Mood Lighting: Extending the application, special lights can be installed which can change the lighting of the room according to the mood of the user.

The Aura system (algorithm) was later bought by our peers who started their own home automation company.