Attitude control of quadrotor with on-board visual feature projection system

Recently many researches have been studied to run autonomous flying vehicles. Especially, quadrotor VTOL (Vertical Take-Off and Landing) has been a challenging subject. To stabilize the quadrotor system, many control algorithms and sensor systems have been developed. Most of them are based on the sensors like accelerometer, gyroscope, or IMU (Inertial Measurement Unit) to measure the attitude of quadrotor. Instead of using these conventional sensors, we apply one vision sensor to stabilize the attitude of a quadrotor system. To achieve this, four laser diodes are evenly distributed in the bottom plane of quadrotor, and then they point downwards. The positions of projected laser markers depend on the attitude and height of the quadrotor. We develop a control algorithm to stabilize the attitude as well as to control the height of a quadrotor. We show that the visual tracking of the laser markers is sufficient to estimate the state of the quadrotor attitude and control the attitude into a desired state.