# Non-Contact and Non-Intrusive Add-on IoT Device for Wireless Remote Elevator Control
## 2 Related Work
### Non-Contact Elevator Control  
The use of non-contact technologies for elevator control has been analyzed in the scientific literature. [PERSON] et al. [6] investigated the integration of touchless technology in public infrastructures in order to remove the need of touching the buttons of control panels located in public or shared spaces. One of their recommendations was the use of an add-on console device equipped with a proximity sensor to allow people to call the elevator by placing their hand in front of it. Similarly, [PERSON] et al. [39] conducted an online survey with 40 adults with different physical disabilities about their experiences with sensing systems. They presented the challenges they faced when interacting with motion sensors, biometric sensors, speech input, and touch and gestures systems. Some of the problems reported were the challenges that represent the visual or sensory identification of a button panel, the reach of the console button panel, and the application of the correct amount of pressure when interacting with its buttons.  
In this direction, the development of Internet-of-Things devices is an emerging field with potential to improve the quality of life of people with disabilities [40]. Another common proposal to achieve non-contact control of elevators is the use of speech-recognition based alternatives. For example, [PERSON] et al. [41] presented a non-contact proposal for elevator control based on speech recognition. [PERSON] et al. [42] proposed a contactless, voice-activated elevator-control panel combined with the use of electromagnetic switches attached to the original elevator button panel. Similarly, [PERSON] et al. [43] proposed a contactless CNN-based single-command speech recognition system to control elevators using the voice with the aim of reducing the challenge that elevators represent for people with disabilities. [PERSON] et al. [44] presented a voice recognizing system for people with paraplegia and visual impairments. However, the use of an elevator by people with severe physical disabilities may require the development of specialized interfaces. [PERSON] et al. [45] presented a brain-computer interface (BCI) solution for elevator control. Their prototype uses brain signals to provide means of communication between users and elevators. They demonstrated that elevators with BCI functionalities [46] can be affordable and are feasible from a practical point of view. Extended information on BCI can be found in the review presented by [PERSON] et al. [46].  
One of the common limitations of the above-mentioned reference works is that their implementation may require some degree of intrusive manipulation of the structure or electrical wiring of the elevator. This limitation has been addressed in this work by proposing an optimized, battery-operated IoT device for remote elevator control that does not require any kind of structural or electrical manipulation of the original elevator. This implementation has potential to allow the rapid deployment of specific functionalities to assist people with disabilities in the use of elevators.