Acrobatics quadrocopters

The most difficult tasks for balancing quadrocopters so far have been balancing the reverse pendulum and juggling balls . Specialists from the Institute of Dynamic Systems and Control in Zurich managed to solve these problems simultaneously. Now quadcopters are not just balancing the reverse pendulum, but also juggling them, throwing each other.

If you are not sure that this is possible, see the video below.


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Juggling with an inverse pendulum is a complex mathematical task. Initially, a computer model was created to test the existence of a theoretical possibility of its solution. The model produced ideal trajectories: the position, speed and angle of inclination of the quadrocopter in order to catch the flying pendulum and maintain its balance.

At the next stage, the engineers tested the mathematical model in real conditions and conducted many tests to verify the parameters set in the model: the aerodynamic properties of the pendulum, the time of the pendulum's separation from the quadcopter, the behavior of the object at the moment of collision with the quadcopter platform. It turned out that in a collision unpredictable rebounds are possible, so that the ends of the pendulum are equipped with shock absorbers: these are bags filled with flour on moving metal bases. By the way, the accident at 1:36 the video is connected with the shock absorber rupture.



The program for controlling quadrocopters was supplemented by several modules:

• The state estimation module for more accurate positioning of the quadrocopter in space and analysis of when a collision with a pendulum and switching from a catch program to a balancing program will occur.
• Fast trajectory generator for calculating the trajectory of a flying pendulum and preliminary approximation to a point.
• Self-learning algorithm for correcting systematic errors based on the parameters of the mathematical model.

via Robohub