Crawling microrobot actuated by a magnetic navigation system in tubular environments

•We developed a crawling microrobot which can effectively move forward and backward and which can anchor in various tubular environments with asymmetric friction force.•We utilized a magnetic navigation system to generate uniform magnetic field which actuates the crawling microrobot.•We developed a three-dimensional control methodology to precisely control the magnetic field and the motion of the microrobot by controlling the currents of a magnetic navigation system.

This paper proposes a crawling microrobot that can effectively navigate and anchor in various tubular environments including human blood vessels and pipes. The microrobot is a multibody structure comprising independently rotatable magnetic bodies with flexible legs and connecting rods. It can resist gravity and fluidic drag forces due to the moving mechanism using asymmetric friction force at the contact point between the leg and wall of the tube. Since the oscillating magnetic field generated by a magnetic navigation system (MNS) can induce oscillating motion of the microrobot, forward and backward crawling motions of the microrobot can be generated by controlling the currents in the MNS. This paper also proposes a methodology to effectively generate a three-dimensional (3D) oscillating magnetic field for the precise manipulation of the microrobot in a 3D tubular environment. Experiments in various environments were performed to verify the proposed microrobot.