摘要：The paper presents a very simple manipulator, which can describe a circular trajectory, in order to position a scanning device for inspecting the external surface of a pipe. The open kinematic chain has only three active joints, and for equally spaced scanning positions around the pipe, its inverse kinematics is derived by help of elementary geometry. The manipulator was built as a part of a mobile robot, serving for inspection and monitoring of the pipelines in the oil and gas industry. Being a demonstrator, its joints actuators are micro RC servos, so a calibration operation of each one was also performed.
