Increasing Repeatability of the Perching on Branch for Flapping-Wing Flying Robot

The flapping-wing technology in aerial robotics proposes an alternative way of thrust and lift production rather than the use of high-speed rotary propellers. Those benefits come with the cost of a challenge in take-off and landing. Perching is a good way of landing, similar to real birds in nature; however, impact and slow flight close to perching are difficult tasks. The current flight control presents an average speed of 4(m/s) in the launching and flight, and a slight reduction to 2(m/s) close to perching, approximately. The recently published paper on the perching of flapping-wing flying robots on a branch, on the scale of big-bird size 1.5(m) wingspan, showed a repeatability of 66% [1]. The use of a laser line sensor for last-meter detection and direct actuation of the leg was used to follow the branch close to impact. Here in this work, several modifications have been done to increase the success rate: using feedback on the center-of-mass (CoM) of the robot bird, and the addition of a transformation between the CoM and end-effector of the claw. By this means the correction of the leg-claw position receives feedback from the motion capture system. So, by using more precise feedback and a control transformation, better reliability is expected. The white background for the line sensor is not necessary anymore which is another advantage of this proposed approach. The proposed method resulted in a more reliable way of flight, branch detection, and perching, increasing the repeatability percentage rate to 88.3 %.