Multiple mobile robots can complement each other. Flying systems typically have a good overview, while rovers can carry heavy loads like scientific instruments or other robots. Crawlers are potentially better in very difficult terrain.
In April 2013, we have demonstrated the first steps toward cooperative exploration in a heterogeneous team that consists of a rover and a multicopter. Both systems perform stereo vision based autonomous waypoint navigation without external infrastructure (e.g. no external tracking or GPS) in unknown, natural terrain. The operator only selects target points in the camera images or in the emerging maps that the systems create.