Control techniques for mechatronic assisted surgery

The treatment response for traumatic head injured patients can be improved by using an autonomous robotic system to perform basic, time-critical emergency neurosurgery, reducing costs and saving lives. In this thesis, a concept for a neurosurgical robotic system is proposed to perform three specific emergency neurosurgical procedures; they are the placement of an intracranial pressure monitor, external ventricular drainage, and the evacuation of chronic subdural haematoma. The control methods for this system are investigated following a curiosity led approach. Individual problems are interpreted in the widest sense and solutions posed that are general in nature. Three main contributions result from this approach: 1) a clinical evidence based review of surgical robotics and a methodology to assist in their evaluation, 2) a new controller for soft-grasping of objects, and 3) new propositions and theorems for chatter suppression sliding mode controllers. These contributions directly assist in the design of the control system of the neurosurgical robot and, more broadly, impact other areas outside the narrow con nes of the target application. A methodology for applied research in surgical robotics is proposed. The methodology sets out a hierarchy of criteria consisting of three tiers, with the most important being the bottom tier and the least being the top tier. It is argued that a robotic system must adhere to these criteria in order to achieve acceptability. Recent commercial systems are reviewed against these criteria, and are found to conform up to at least the bottom and intermediate tiers. However, the lack of conformity to the criteria in the top tier, combined with the inability to conclusively prove increased clinical benefit, particularly symptomatic benefit, is shown to be hampering the potential of surgical robotics in gaining wide establishment. A control scheme for soft-grasping objects is presented. Grasping a soft or fragile object requires the use of minimum contact force to prevent damage or deformation. Without precise knowledge of object parameters, real-time feedback control must be used to regulate the contact force and prevent slip. Moreover, the controller must be designed to have good performance characteristics to rapidly modulate the fingertip contact force in response to a slip event. A fuzzy sliding mode controller combined with a disturbance observer is proposed for contact force control and slip prevention. The robustness of the controller is evaluated through both simulation and experiment. The control scheme was found to be effective and robust to parameter uncertainty. When tested on a real system, however, chattering phenomena, well known to sliding mode research, was induced by the unmodelled suboptimal components of the system (filtering, backlash, and time delays). This reduced the controller performance. The problem of chattering and potential solutions are explored. Real systems using sliding mode controllers, such as the control scheme for soft-grasping, have a tendency to chatter at high frequencies. This is caused by the sliding mode controller interacting with un-modelled parasitic dynamics at the actuator-input and sensor-output of the plant. As a result, new chatter-suppression sliding mode controllers have been developed, which introduce new parameters into the system. However, the effect any particular choice of parameters has on system performance is unclear, and this can make tuning the parameters to meet a set of performance criteria di cult. In this thesis, common chatter-suppression sliding mode control strategies are surveyed and simple design and estimation methods are proposed. The estimation methods predict convergence, chattering amplitude, settling time, and maximum output bounds (overshoot) using harmonic linearizations and invariant ellipsoid sets

Kinematic analysis of a novel 2-d.o.f. orientation device

This paper presents the development of a new parallel robot designed for helping with bone milling surgeries. The robot is a small modular wrist with 2 active degrees of freedom, and it is proposed to be used as an orientation device located at the end of a robotic arm designed for bone milling processes. A generic kinematic geometry is proposed for this device. This first article shows the developments on the workspace optimization and the analysis of the force field required to complete a reconstruction of the inferior jawbone. The singularities of the mechanism are analyzed, and the actuator selection is justified with the torque requirements and the study of the force space. The results obtained by the simulations allow building a first prototype using linear motors. Bone milling experiment video is shown as additional material

Kinematics analysis of 6-DOF parallel micro-manipulators with offset u-joints : a case study

This paper analyses the kinematics of a special 6-DOF parallel micro-manipulator with offset RR-joint configuration. Kinematics equations are derived and numerical methodologies to solve the inverse and forward kinematics are presented. The inverse and forward kinematics of such robots compared with those of 6-UCU parallel robots are more complicated due to the existence of offsets between joints of RR-pairs. The characteristics of RR-pairs used in this manipulator are investigated and kinematics constraints of these offset U-joints are mathematically explained in order to find the best initial guesses for the numerical solution. Both inverse and forward kinematics of the case study 6-DOF parallel micro-manipulator are modelled and computational analyses are performed to numerically verify accuracy and effectiveness of the proposed methodologies

Medical Robotics

The first generation of surgical robots are already being installed in a number of operating rooms around the world. Robotics is being introduced to medicine because it allows for unprecedented control and precision of surgical instruments in minimally invasive procedures. So far, robots have been used to position an endoscope, perform gallbladder surgery and correct gastroesophogeal reflux and heartburn. The ultimate goal of the robotic surgery field is to design a robot that can be used to perform closed-chest, beating-heart surgery. The use of robotics in surgery will expand over the next decades without any doubt. Minimally Invasive Surgery (MIS) is a revolutionary approach in surgery. In MIS, the operation is performed with instruments and viewing equipment inserted into the body through small incisions created by the surgeon, in contrast to open surgery with large incisions. This minimizes surgical trauma and damage to healthy tissue, resulting in shorter patient recovery time. The aim of this book is to provide an overview of the state-of-art, to present new ideas, original results and practical experiences in this expanding area. Nevertheless, many chapters in the book concern advanced research on this growing area. The book provides critical analysis of clinical trials, assessment of the benefits and risks of the application of these technologies. This book is certainly a small sample of the research activity on Medical Robotics going on around the globe as you read it, but it surely covers a good deal of what has been done in the field recently, and as such it works as a valuable source for researchers interested in the involved subjects, whether they are currently “medical roboticists” or not

Human-Robot Collaborative Force-Controlled Micro-Drilling for Advanced Manufacturing and Medical Applications

Robotic drilling finds applications in diverse fields ranging from advanced manufacturing to the medical industry. Recent advances in low-cost, and human-safe, collaborative robots (e.g., Sawyer) are enabling us to rethink the possibilities in which robots can be deployed for such tedious and time-consuming tasks. This thesis presents a robotic drilling methodology with features of force-control enabled micro-drilling and human-robot collaboration to reduce programming efforts and enhance drilling performance. A Sawyer robot from Rethink Robotics, which offers safe physical interactions with a human co-worker, kinesthetic teaching, and force control, is used as the test bed. The robot’s end-effector was equipped with a Dremel drill fit into a housing, which was custom designed and 3D-printed using an Object Prime 3D-printer. The proposed approach applies human-robot collaboration in two cases. First, a human kinesthetically teaches a set of drill coordinates by physically holding the robot and guiding it to those locations. The robot then executes the drilling task by moving to these recorded locations. This thereby avoids the need to specify the drill coordinates with respect to a fixed reference frame, leading to reduction in programming effort and setup time while transitioning between different drilling jobs. Second, drilled hole quality is shown to be enhanced when a human provides nominal physical support to the robot during certain drilling tasks. An experimental analysis of the impact of force control on micro-drilling revealed that the proposed robotic system is capable of successfully drilling holes with a drill bit of 0.5 mm diameter with an error of +/- 0.05 mm, without breaking it for more than 100 holes. The proposed robotic drilling was validated in the following application domain: micro-drilling for composite repairs based on the through-thickness reinforcement (TTR) technique. For this purpose, sandwich beam samples were prepared by using pre-preg unidirectional carbon fabric face sheets with a honeycomb core, and they were subjected to four-point static loading until de-bonding occurred between the face sheet and the core. The samples were then repaired using the TTR technique, where the proposed robotic drilling was used to drill holes of 0.75 mm diameter in the damaged area of the sample and carbon fiber rods and with low-viscosity epoxy, were manually inserted into these drilled holes. The results revealed that the sandwich beam regained effective compressive strength after going through the TTR technique. Experiments also reveal the potential of the proposed robotic drilling technique in aerospace and automotive manufacturing involving drilling in complex postures and micro-drilling for orthopedic applications

Flexible robotic device for spinal surgery

Surgical robots have proliferated in recent years, with well-established benefits including: reduced patient trauma, shortened hospitalisation, and improved diagnostic accuracy and therapeutic outcome. Despite these benefits, many challenges in their development remain, including improved instrument control and ergonomics caused by rigid instrumentation and its associated fulcrum effect. Consequently, it is still extremely challenging to utilise such devices in cases that involve complex anatomical pathways such as the spinal column. The focus of this thesis is the development of a flexible robotic surgical cutting device capable of manoeuvring around the spinal column. The target application of the flexible surgical tool is the removal of cancerous tumours surrounding the spinal column, which cannot be excised completely using the straight surgical tools in use today; anterior and posterior sections of the spine must be accessible for complete tissue removal. A parallel robot platform with six degrees of freedom (6 DoFs) has been designed and fabricated to direct a flexible cutting tool to produce the necessary range of movements to reach anterior and posterior sections of the spinal column. A flexible water jet cutting system and a flexible mechanical drill, which may be assembled interchangeably with the flexible probe, have been developed and successfully tested experimentally. A model predicting the depth of cut by the water jet was developed and experimentally validated. A flexion probe that is able to guide the surgical cutting device around the spinal column has been fabricated and tested with human lumber model. Modelling and simulations show the capacity for the flexible surgical system to enable entering the posterior side of the human lumber model and bend around the vertebral body to reach the anterior side of the spinal column. A computer simulation with a full Graphical User Interface (GUI) was created and used to validate the system of inverse kinematic equations for the robot platform. The constraint controller and the inverse kinematics relations are both incorporated into the overall positional control structure of the robot, and have successfully established a haptic feedback controller for the 6 DoFs surgical probe, and effectively tested in vitro on spinal mock surgery. The flexible surgical system approached the surgery from the posterior side of the human lumber model and bend around the vertebral body to reach the anterior side of the spinal column. The flexible surgical robot removed 82% of mock cancerous tissue compared to 16% of tissue removed by the rigid tool.Open Acces

Robotic Assistant Systems for Otolaryngology-Head and Neck Surgery

Recently, there has been a significant movement in otolaryngology-head and neck surgery (OHNS) toward minimally invasive techniques, particularly those utilizing natural orifices. However, while these techniques can reduce the risk of complications encountered with classic open approaches such as scarring, infection, and damage to healthy tissue in order to access the surgical site, there remain significant challenges in both visualization and manipulation, including poor sensory feedback, reduced visibility, limited working area, and decreased precision due to long instruments. This work presents two robotic assistance systems which help to overcome different aspects of these challenges. The first is the Robotic Endo-Laryngeal Flexible (Robo-ELF) Scope, which assists surgeons in manipulating flexible endoscopes. Flexible endoscopes can provide superior visualization compared to microscopes or rigid endoscopes by allowing views not constrained by line-of-sight. However, they are seldom used in the operating room due to the difficulty in precisely manually manipulating and stabilizing them for long periods of time. The Robo-ELF Scope enables stable, precise robotic manipulation for flexible scopes and frees the surgeon’s hands to operate bimanually. The Robo-ELF Scope has been demonstrated and evaluated in human cadavers and is moving toward a human subjects study. The second is the Robotic Ear Nose and Throat Microsurgery System (REMS), which assists surgeons in manipulating rigid instruments and endoscopes. There are two main types of challenges involved in manipulating rigid instruments: reduced precision from hand tremor amplified by long instruments, and difficulty navigating through complex anatomy surrounded by sensitive structures. The REMS enables precise manipulation by allowing the surgeon to hold the surgical instrument while filtering unwanted movement such as hand tremor. The REMS also enables augmented navigation by calculating the position of the instrument with high accuracy, and combining this information with registered preoperative imaging data to enforce virtual safety barriers around sensitive anatomy. The REMS has been demonstrated and evaluated in user studies with synthetic phantoms and human cadavers