中文摘要：

针对有向拓扑关系图研究了时离散多智能体系统的可控性问题。证明了系统能控的必要条件是跟随者在收到一个多智能体发来信息的同时，必须也要收到从其它多智能体发来的信息。此外，还给出了通过改变权重来使某些系统可控的方法。通过一个例子及其仿真对所得结论进行了验证。

英文摘要：

In this paper, the controllability problem is analyzed for discrete-time multi-agent systems under directed interconnection topologies. It is proved that the necessary condition for a system to be controllable is that there are no two followers which can only receive information from the same agent. Also an approach is proposed to transform an uncontrollable system to a controllable one by assigning weights between agents. An example is given to illustrate the ideas and the corresponding results.