A vital perception in designing human-machine interfaces for people with disabilities is hands-free control. It is important in setting up communication among a machine and the part of human body. Nowadays, hands-free control is extensively used to help disabled people to control the wheelchair. The hands-free control functions are not only helpful to elderly and disabled, but also useful for normal people who might require using their hands for other tasks at the same time. As a result, normal people are capable of manipulating multiple tasks at the same time. The wheelchair is manoeuvred using brainwaves, eyes and facial muscles movements, voice, tongue, gesture. The mobility using a powered wheelchair improves the quality of life of the aged people and the people with mobility impairments significantly. These powered wheelchairs can be actuated using various high-level control interfaces. In this review, the use of natural biological signals and non-biological signal to do the hands-free control of powered wheelchair is presented in this article.