Abstract: Both the dead-zone and friction are often unknown in DC servo systems. Besides, the error caused by speed measurement often exists. All of these above factors may severely affect the system's performance. Hence, this paper presents a robust adaptive controller to cope with these problems. The proposed algorithm is rigorously proved by using Lyapunov theory. Another feature in this paper is that a kind of differentiator is utilized to estimate the speed such that the error caused by speed measurement can be reduced. The simulation results show that the proposed method can improve system's speed estimation, and it is effective for promoting the efficacy of friction and deadzone compensation.