Abstract: A collaborative direction estimation method based on single frequency sound is proposed for swarm-based robotic systems. A sense array of microphones based on interaurla intensity difference (IDD) is designed. According to the characteristics of sound intensity signals of the sense array, the relationship between sound intensity signals of sensors and sound source direction is deduced with fuzzy inference system (FIS). Experimental results show that this direction estimation method can meet the requirements ofdirection estimation of swarm-based robotic systems.