Recent advancement in research fields involving computer science and Artificial Intelligence has influence the rapid growth in smart wheelchair research. Another factor adding to this growth is the evolution of sensor and computing technology. Basically, a smart wheelchair is a powered wheelchair that has been modified by adding necessary sensors and instruments that able to read, collect and send information that can be used to modify the status of the wheelchair, as well as interacting with the environment or the user. The modification can be done on various part of the wheelchair system, and can be categorized with their input methods, operating system or their navigation system itself. This paper discussing on various input methods used in recent smart wheelchair research and summarizes the ideas presented.