A Novel tele-operation controller for wireless microrobots in-pipe with hybrid motion

•We developed a novel tele-operation system with a controller for medical applications.•We designed a novel wireless hybrid microrobot with a gravity compensation mechanism.•The control algorithm is based on an eight-step rotating magnetic field.•Experiments validated the eight-step control algorithm and tele-operation system.

Intracavity intervention is expected to become increasingly popular in medical practice for both diagnosis and surgery. Wireless microrobots are employed in a wide range of biomedical application and they may have the potential to accomplish various radical medical procedures because they can be transported deep into the human body to perform tasks safely and reliably. In particular, colonoscopy is an important procedure during the diagnosis of various pathologies, especially cancer of the colon and rectum. However, the colonoscopy process is often painful for the patient and complex for the operator, so wireless microrobots could be employed for the early diagnosis of gastrointestinal malignant tumors. In this study, we developed a novel tele-operation system that can be used in biomedical applications, where we designed a master controller and slaver controller for the system. We also designed a novel type of wireless microrobot with hybrid motion, which can be driven by differences in an external magnetic field. Thus, a doctor could operate joysticks from the master side to control the wireless microrobot on the slave side in real time. Using a control algorithm based on an eight-step rotating magnetic field, the slave controller can generate a more uniform rotating magnetic field and avoid many of the problems that affect traditional control methods. We evaluared the performance of a tele-operated controller and the wireless microrobot with hybrid motion in experiments. The experimental results indicated that the wireless microrobot with hybrid motion could complete forward–backward and upward–downward movements easily with similar kinematic characteristics, where the available frequency band was widened by the control algorithm based on an eight-step rotating magnetic field. The maximum velocity was measured as 29.8 mm/s at around 18 Hz in the horizontal direction and as 9.6 mm/s at around 16 Hz in the vertical direction with an input current of 0.7 A. The tele-controller obtained good performance in the experiments and it could be used widely in medical clinics in the future.