Stabilization of a roll-tilt camera on an autonomous quadrotor helicopter

Abstract

Harmful algal blooms are becoming an increasingly difficult problem to deal with, particularly in Singapore. The Center for Environmental Sensing and Modeling (CENSAM) has developed a network of autonomous vehicles to nd blooms when they occur. The problem is that finding blooms, which are often transient in nature, can be difficult, particularly with slow-moving underwater and surface vehicles. Autonomous "quadrotor" helicopters are being utilized to visually survey large areas to spot these blooms while they are occurring. Here we develop a model for implement- ing servo motor controlled camera stabilization on these autonomous vehicles. The need for camera stabilization arises because video footage is monitored continuously while the onboard GPS is controlling the motion of the quadrotor. The operator of the quadrotor may not want to look in the direction that the GPS controller would like to guide the vehicle. We explore implementing a system that gives the operator the ability to control the camera, yet maintain the autonomous nature of the quadrotor. We develop two models for the rotations involved in stabilizing the position and orientation of the camera against the motion of the vehicle it is mounted on. We use these models to investigate the limitations this type of active stabilization would im- pose on our quadrotor and GPS controller, and discuss the next steps in integrating it into our system.