Abstract: Multi-function artificial intelligence crawler(MAIC-1) was developed to accomplish TOFD inspection for the welding of block construction of hull. A steering control strategy of electronic differential speed was proposed to meet the requirement of TOFD procedure, and a pose estimation algorithm based on encoder in servo motor was developed. The control system design was described from hardware and software aspects. The experiments showed that the control system based on the steering control strategy of electronic differential speed could drive the crawler flexibly with suitable maneuverability of crawler control. The algorithm of pose estimation based on encoders without extra sensors was verified by experiments. The algorithm had great potential for crawler operation assistant and automation.