Optimal Control of a Universal Rotating Magnetic Vector for Petal-shaped Capsule Robot in Curve Environment

Steering control of a capsule robot in curve environment by magnetic navigation is not yet solved completely.A petal-shaped capsule robot with less steering resistance based on multiple wedge effects is presented,and an optimization method with two processes for determining the orientation of a pre-applied universal magnetic spin vector is proposed.To realize quick and non-contact steering swimming,a fuzzy comprehensive evaluation method for optimizing the steering driving angle is presented based on two evaluation indexes including the average steering speed and the average steering trajectory deviation,achieving the initial optimal orientation of a universal magnetic spin vector.To further reduce robotic magnetic vibration,a main target method for optimizing its final orientation,which is used for fine adjustment,is employed under the constrains of the magnetic moments.Swimming experimental results in curve pipe verified the effectiveness of the optimization method,which can be effectively used to realize non-contact steering swimming of the petal-shaped robot and reduce its vibration.

Control strategy for multiple capsule robots in intestine

Based on the critical gap phenomenon of the intestinal capsule robot,a variable-diameter capsule robot with radial gap self-compensation is developed in this paper.With the functional variation principle,a fluid dynamic pressure model satisfying the boundary conditions of the outer surface of capsule robot with screw blades is derived.The critical gap phenomenon is studied theoretically and experimentally based on the end effect and the dynamic balance characteristics of the fluid on the surface of capsule robot.The concept of start-up rotation speed is defined,the relationship between the start-up rotation speed and the spiral parameters of capsule robot is investigated.The strategy for implementing drive and control on several capsule robots under the same rotational magnetic field is proposed,and by defining the start-up curves of several capsule robots with the similar motion regulation as the objective functions,genetic algorithm is employed to optimize the spiral parameters of several capsule robots.Experiments have shown that the proposed drive and control strategy for several capsule robots can be implemented effectively.It has a good prospect of application inside intestine to realize the drive and control on several capsule robots for different medical purposes.

Control theorem of a universal uniform-rotating magnetic vector for capsule robot in curved environment

For realizing non-contact steering swimming of a capsule robot in curved environment filled with viscous liquid, based on spa- tial orthogonal superposition theorem of alternating magnetic vectors, an innovative physical method is proposed, which em- ploys three-axis orthogonal square Helmholtz coils fed with three phase sine currents to create a universal uniform magnetic spin vector as energy source. According to the antiphase sine current superposition theorem generalized in this paper, an effec- tive control method for successively adjusting the orientation and the rotating direction of the universal magnetic spin vector is proposed. For validating its feasibility and controllability, three-axis Helmholtz coils, power source and an innovative capsule robot prototype were manufactured, experiments were conducted in both spiral pipe and animal intestine. It was demonstrated that the orientation and the rotational direction of the universal uniform-magnetic spin vector can be adjusted successively through digital control and steering swimming of the capsule robot in spiral intestine can be achieved successfully. The breakthrough of the universal rotating uniform-magnetic vector will push forward the development of modern physics and biomedical engineering

Design of Multi-Coil Wireless Power Transfer System for Gastrointestinal Capsule Robot

The existing wireless power transfer(WPT)systems for gastrointestinal capsule robot have the prob-lems of small coupling coefficient and low power transmission efficiency(PTE).The reasons are due to the long distance between the transmitting coil and the receiving coil and the large difference in size.A new type of WPT system is designed,which uses three sets of small coil pairs to form a power supply unit(PSU),and utilizes multiple PSUs to form a multi-coil WPT system.Compared with single-coil system,the multi-coil system can achieve higher power utilization by switching between PSUs,instead of opening all PSUs.ANSYS Maxwell is used to perform finite element modeling on the PSU,analyzing the characteristics of the transmitting magnetic field.The results of the experiment show that when the distance between the small coil pairs in the PSU is 180mm,the magnetic field has relatively good uniformity,and the magnetic strength change relative to the center point is less than 5%.The average received power of the system is greater than 800mW,and the PTE is up to 5.1%.

Localization of a Robotic Capsule for GI Motility Inspection with a Portable Ultrasonic System

The micro-systems used for in vivo physical inspection have many advantages over traditional methods. In order to aid diagnosis of gastrointestinal (GI) motility disorders, a capsule is developed for GI pressure and pH inspection. Localization of the capsule in GI tract with time is a necessary condition for subsequent data analysis and medical diagnosis. It is also a common problem facing all in vivo mobile micro-systems. An approach of segment localization by utilizing some key points along GI tract is proposed. A portable ultrasonic detecting device was designed for this purpose. Experiments under conditions similar to GI tract were carried out and the results proved the effectiveness and reliability of this method and the device.

Orthogonal transformation operation theorem of a spatial universal uniform rotating magnetic field and its application in capsule endoscopy

According to the anti-phase sine current superposition theorem, the orientation, the magnetic flux density, the angular speed and the rotational direction of the spatial universal rotating magnetic field (SURMF) can be controlled within the tri-axial orthogonal square Helmholtz coils (TOSHC). Nevertheless, three coupling direction angles of the normal vector of the SURMF in the Descartes coordinate system cannot be separately controlled, thus the adjustment of the orientation of the SURMF is difficult and the flexibility of the robotic posture control is restricted. For the dimension reduction and the decoupling of control variables, the orthogonal transformation operation theorem of the SURMF is proposed based on two independent rotation angular variables, which employs azimuth and altitude angles as two variables of the three-phase sine current superposition formula derived by the orthogonal rotation inverse transformation. Then the unique control rules of the orientation and the rotational direction of the SURMF are generalized in each spatial quadrant, thus the scanning of the normal vector of the SURMF along the horizontal or vertical direction can be achieved through changing only one variable, which simplifies the control process of the orientation of the SURMF greatly. To validate its feasibility and maneuverability, experiments were conducted in the animal intestine utilizing the innovative dual hemisphere capsule robot (DHCR) with active and passive modes. It was demonstrated that the posture adjustment and the steering rolling locomotion of the DHCR can be realized through single variable control, thus the orthogonal transformation operation theorem makes the control of the orientation of the SURMF convenient and flexible significantly. This breakthrough will lay a foundation for the human-machine interaction control of the SURMF.