Trajectory Generation of a Quadrotor Transporting a Bulky Payload in the Cluttered Environments

When an aerial robot carries a bulky and heavy payload, it suffers from a wavering effect because of the large inertia of the heavy mass of a payload, which can cause a serious crash or fall to the ground. We propose the path-planning algorithm for an aerial robot to pass a narrow space while transporting a bulky payload to resolve the issue. Unlike the existing conventional path-planning method that treats the payload as a point-mass, this paper generates the trajectory considering the shape of a payload and passage size of an Unmanned Aerial Vehicle (UAV). First, we design a map-generation algorithm with the Voronoi diagram by exploiting the fact that the UAV has an ellipsoidal shape in transport operation with a bulky object. The modified map data can be exploited for the global path generation such as A* path-planner. For the rotational motion of the UAV, the heading angle was determined by considering the lengths of the major and minor axes of the ellipse. The global path was optimized based on the elastic band optimization algorithm to solve the jerky motion on the trajectory. Through the simulations and experiments, we validate the efficiency of our algorithm in the environment with the narrow space. Experimental results showed that the proposed path-planning algorithm could be used for safe aerial transportation in realistic environments.