In the last decade, mobile robot swarms are widely used in wild applications, such as disaster search and rescue, battlefield communication, and so on. Due to their task-oriented feature in the wild, robot nodes usually move in groups. However, the communication of self-organized networks as a fundamental technology of mobile robot swarms is still the main bottleneck to restrict its developments. We propose servo relays as distributed controllable-mobility network (i.e., Servo-R network) to maintain long-term stable links for mobile robot swarms. In Servo-R network, servo relay is more like a slave. If one group of mobile robots needs a relay, it serves them. Otherwise, servo relay always stands alone and is ready to provide its relay service at any time. Servo-R network is an ensemble of controllable mobility and relay routing schemes. Controllable mobility scheme uses an iterated auction algorithm to assign servo relays to groups. Besides, it uses the virtual force and predicted location methods to realize the controllable movements of relays and base station. As a fully distributed scheme, the dynamic deployments of servo relays and base station are suitable to fight against the frequent topology changes of mobile robot swarm. According to the location information of the group's nodes, relay routing scheme uses dynamic programming to compute the group route table with the least hops. According to the received group route table, the group's nodes forward data. This is good to improve packet delivery ratio. In the various scenarios of our simulation, Servo-R outperforms four compared protocols in most cases, especially in the network connectivity and link duration.