For a few years, several research projects have focused on swarms of autonomous mobile robots (e.g., aircraft vehicles, ground robots). The overall cost (including price, weight, energy, etc.) of the payload required by some missions is sometimes too important to enable the robots of the swarm to embed all the required capabilities (i.e., sensors and actuators). This is the reason why it is more suitable to spread all the capabilities among the robots of the swarm. In this case, it is necessary to implement a collaborative system inside the swarm in order to share the capabilities among them. This collaborative system should provide task allocation as well as management of conflicts and failures which can occur at any moment. In this paper, we present a novel collaborative system for heterogeneous swarms of autonomous mobile robots called AMiRALE (Asynchronous Missions Relay for Autonomous and Lively Entities). Our system if fully distributed and relies only on asynchronous communications. We provide a formal description of our proposal based on a graph relabeling system. We also present experimental results obtained through both simulation and emulation. Our evaluation is based on a park cleaning scenario which relies on autonomous and specialized ground robots.