Flexible three-dimensional robotic system with tomographic magnetic actuation

Abstract

Magnetic strategies implemented within the framework of flexible robotics represent an alternative for procedures where it is necessary to have a safe interaction for the user, taking advantage of the untethered movement, such as in the so-called minimally invasive procedures, performed in clinical environments. This thesis proposes the development of a flexible robotic magnetic structure controlled by an array of electromagnetic actuators arranged in a configuration inspired by the movement generated in tomographs, based on a multi-layer approach with rotatory motion. A first prototype, based on a simple magnetic pendulum controlled by electromagnetic actuators, serves to analyze the interaction between the magnetic fields generated in the system, while the second one illustrates the proof-of-concept of the multi-layer system with tomographic motion. For both prototypes, the scope of the thesis considers the design of the robotic structure and its mathematical modeling; the construction of the system; and its control and evaluation. The mathematical model of the systems considers the description of the interaction of the generalized forces generated by the electromagnetic actuators over the magnetic structure, which is based on a novel methodology proposed within the scope of the thesis and that considers the utilization only of algebraic expressions to approximate the force between electromagnets and permanent magnets. Furthermore, due to the nature of the interaction of the magnetic fields, which requires the magnetic elements not to be at close contact so that they can be separated, the prototype considers the inclusion of boundaries established at first in the mechanical structure to limit the range of movement and further implemented in the control algorithm by means of a Barrier Lyapunov Function (BLF). The results show that the proposed functions of the interaction of magnetic forces yield approximated results that are useful for its application in models for robotic systems. Regarding the robotic systems, it is possible to show the capability of electromagnetic actuators to generate untethered motion over magnetic structures, particularly for the proposed flexible magnetic structure with tomographic magnetic actuation, representing an alternative for robotic systems with wireless movement.