Distributed Model Predictive Formation Control of Robots with Sampled Trajectory Sharing in Cluttered Environments

In this paper, we propose a Model Predictive Control (MPC) based distributed formation control method for a multi-robot system (MRS) that would move them among dynamic obstacles to a desired goal position. Specifically, after formulating the formation control, as a distributed version of MPC, we propose and evaluate three information-sharing schemes within the MRS; namely sharing (i) positions, (ii) complete predicted trajectories, and (iii) exponentially-sampled predicted trajectories. Using a simplified kinematic model for robots, we conducted systematic simulation experiments in (a) scenarios, where the robots are instructed to switch places, as one of the most challenging forms of formation changes, and in (b) scenarios where robots are instructed to reach a goal, within environments containing dynamic obstacles. In a set of systematic experiments conducted in simulation and with mini quadcopters, we have shown that sharing of exponentially-sampled trajectories (as opposed to positions, or complete trajectories) among the robots provides near-optimal paths while decreasing the required computation cost and communication bandwidth. Surprisingly, in the presence of noise, sharing exponentially-sampled trajectories among the robots decreased the variance in the final paths. The proposed method is demonstrated on a group of Crazyflie quadcopters.