An open-source architecture for control and coordination of a swarm of micro-quadrotors

Abstract

This work presents the design of an open-source control architecture specifically tailored to the rapid development and testing of control and coordination algorithms on micro quadrotors. The proposed design extends an existing open-source and open-hardware quadrotor project, i.e., the Crazyflie nano quadrotor, by adding the guidance, navigation and control layers required to accomplish autonomous flight. The control layer, in particular, is based on a cascade control algorithm able to globally stabilize the position and the attitude of the vehicle. The global property guaranteed by the algorithm allows the quadrotors to perform aggressive maneuvers. The guidance layer is designed to coordinate simultaneously multiple vehicles by generating suitable reference trajectories. Experiments demonstrate the effectiveness of the proposed design. This research has been conducted in part under the collaborative project SHERPA supported by the European Community under the 7th Framework Programme.

Decentralized collaborative transport of fabrics using micro-UAVs

“…Other solutions for controlling a swarm of Crazyflies has been considered [7], [8], but they are centralized. As with Preiss et al, their scripts are specific to their implementation for this platform, whereas we leveraged a domain-specific programming language for swarms [9] to guarantee portability to other platforms.…”

Control of a small quadrotor for swarm operation

“…The remote control input consists of desired Euler angles [Φ( • ), Θ( • ), Ψ( • s −1 )] ⊤ and Thrust T , a 16-bit unsigned integer representing total thrust between 0 N and cca 0.6 N [14]. To maintain backwards compatibility with the rest of the system (ie the Crazyflie Client software and the Crazyflie smartphone application), which relies on sending/receiving these commands in degrees, the Euler angles need to be first converted into radians, before being transformed into the quaternion q di [15].…”

“…where k is the torque-thrust coefficient defined as k = kQ kF , such that Q i = kT i . The motor control output is consequently obtained by inverting (15)…”

Implementation and validation of an event-based real-time nonlinear model predictive control framework with ROS interface for single and multi-robot systems

“…A non-NMPC based framework ("CAVIS") for multi robot aerial manipulation is introduced in [8]. Also [9] and [10] are presenting open software platforms for swarm coordination. However, all these control solutions are either task specific or are lacking the desired on-line adaptability.…”

“…(9) is associated with the constraints that are acting on agent i, while (10) is the influence induced by coupling constraints. In reverse conclusion, if (8) is provided for different agents, (9) for different constraints and (10) for different coupling constraints, the summands of this equation can be exchanged according to the dynamics, objective, constraints and couplings. To structure the full OCP, the modularization has to be also executed for the other optimality conditions (6)- (7) In case of (6) this is trivial, as it results in a concatenation of system dynamics.…”