No abstract

In the present work we discuss a novel dynamic control approach for magnetically actuated robots, by proposing an adaptive control technique, robust towards parametric uncertainties and unknown bounded disturbances. The former generally arise due to partial knowledge of the robots' dynamic parameters, such as inertial factors, the latter are the outcome of unpredictable interaction with unstructured environments. In order to show the application of the proposed approach, we consider controlling the Magnetic Flexible Endoscope (MFE) which is composed of a soft-tethered Internal Permanent Magnet (IPM), actuated with a single External Permanent Magnet (EPM). We provide with experimental analysis to show the possibility of levitating the MFE-one of the most difficult tasks with this platform-in case of partial knowledge of the IPM's dynamics and no knowledge of the tether's behaviour. Experiments in an acrylic tube show a reduction of contact of the 32% compared to non-levitating techniques and 1.75 times faster task completion with respect to previously proposed levitating techniques. More realistic experiments, performed in a colon phantom, show that levitating the capsule achieves faster and smoother exploration and that the minimum time for completing the task is attained by the proposed approach.

The gastrointestinal (GI) tract is a complex environment comprised of the mouth, esophagus, stomach, small and large intestines, rectum and anus, which all cooperate to form the complete working GI system. Access to the GI using endoscopy has been augmented over the past several decades by swallowable diagnostic electromechanical devices, such as pill cameras.Research continues today and into the foreseeable future on new and more capable miniature devices for the purposes of systemic drug delivery, therapy, tissue biopsy, microbiome sampling, and a host of other novel ground-breaking applications. The purpose of this review is to provide engineers in this field a comprehensive reference manual of the GI environment and its complex physical, biological, and chemical characteristics so they can more quickly understand the constraints and challenges associated with developing devices for the GI space. To accomplish this, the work reviews and summarizes a broad spectrum of literature covering the main anatomical and physiological properties of the GI tract that are pertinent to successful development and operation of an electromechanical device. Each organ in the GI is discussed in this context, including the main mechanisms of digestion, chemical and mechanical processes that could impact devices, and GI motor behavior and resultant forces that may be experienced by objects as they move through the environment of the gut.

Magnetically actuated endoscopes are currently transitioning in to clinical use for procedures such as colonoscopy, presenting numerous benefits over their conventional counterparts. Intelligent and easy-to-use control strategies are an essential part of their clinical effectiveness due to the un-intuitive nature of magnetic field interaction. However, work on developing intelligent control for these devices has mainly been focused on general purpose endoscope navigation. In this work, we investigate the use of autonomous robotic control for magnetic colonoscope intervention via biopsy, another major component of clinical viability. We have developed control strategies with varying levels of robotic autonomy, including semi-autonomous routines for identifying and performing targeted biopsy, as well as random quadrant biopsy. We present and compare the performance of these approaches to magnetic endoscope biopsy against the use of a standard flexible endoscope on benchtop using a colonoscopy training simulator and silicone colon model. The semi-autonomous routines for targeted and random quadrant biopsy were shown to reduce user workload with comparable times to using a standard flexible endoscope.

No abstract

Magnetically actuated robots have become increasingly popular in medical endoscopy over the past decade. Despite the significant improvements in autonomy and control methods, progress within the field of medical magnetic endoscopes has mainly been in the domain of enhanced navigation. Interventional tasks such as biopsy, polyp removal, and clip placement are a major procedural component of endoscopy. Little advancement has been done in this area due to the problem of adequately controlling and stabilizing magnetically actuated endoscopes for interventional tasks. In the present paper we discuss a novel model-based Linear Parameter Varying (LPV) control approach to provide stability during interventional maneuvers. This method linearizes the non-linear dynamic interaction between the external actuation system and the endoscope in a set of equilibria, associated to different distances between the magnetic source and the endoscope, and computes different controllers for each equilibrium. This approach provides the global stability of the overall system and robustness against external disturbances. The performance of the LPV approach is compared to an intelligent teleoperation control method (based on a Proportional Integral Derivative (PID) controller), on the Magnetic Flexible Endoscope (MFE) platform. Four biopsies in different regions of the colon and at two different system equilibria are performed. Both controllers are asked to stabilize the endoscope in the presence of external disturbances (i.e. the introduction of the biopsy forceps through the working channel of the endoscope). The experiments, performed in a benchtop colon simulator, show a maximum reduction of the mean orientation error of the endoscope of 45.8% with the LPV control compared to the PID controller.

No abstract