A QUADCOPTER CONTROLLER TO MAINTAIN RADIO LINK QUALITY

Abstract

The excellent maneuverability and the availability of large number of sensors including good quality video cameras make quadcopters an attractive device for deployment in surveillance systems. Most video surveillance systems require a real-time high quality video to stream from the cameras on the quadcopter to the base-station. This requires a good quality radio link between the quadcopter and the base-station. Furthermore a good link quality is also needed to be maintained to make sure that either control signal or the result from offline processing gets back to the quadcopter without any loss. The link quality depends on the distance of the quadcopter from the base-station; the signal strength decreases with distance. The link quality also depends on the noise of the environment. This study considers the problem of hovering a quadcopter at the maximum distance from the base-station while maintaining a link quality at a given value indicated by the Signal to Noise Ratio (SNR). This solves the problem of having an empirical measurement for the distance on a wireless device. Wherein having a pre-set value for distance does not fully utilize the maximum range it could fly or it would break the communication link if the pre-set value for distance is greater than the communication range. There are existing solution on the field of robotics that incorporates the concept of link aware mobility. However, this is the first time a practical implementation and experiments is considered on the quadcopters. A novel approach is proposed on link aware mobility - An autonomous controller that uses a cognitive based model to learn the SNR change and provide necessary feedback. SNR is a metric that depends on many factors. Therefore a suitable in depth analysis is done on how to use the SNR as a signal metric.