Many users with motor disabilities, such as quadriplegics are unable to handle a power wheelchair securely, without causing harm to others, to themselves or their surroundings. Smart wheelchairs usually have been instrumented with a collection of sensors and computers using systems and algorithms that have been designed to provide safe navigation assistance through collision avoidance. This paper proposes a real-time obstacle avoidance embedded system adapted to work with a multimodal navigation interface. 26 Ultrasonic sensors (Sonars) were used to provide feedback of the distance between the wheelchair and the obstacles.