Gerrit Naus

Cooperative adaptive cruise control, design and experiments

The design of a CACC system and corresponding experiments are presented. The design targets string stable system behavior, which is assessed using a frequency-domain-based approach. Following this approach, it is shown that the available wireless information enables small inter-vehicle distances, while maintaining string stable behavior. The theoretical results are validated by experiments with two CACC-equipped vehicles. Measurement results showing string stable as well as string unstable behavior are discussed.

Robot-assisted vitreoretinal surgery

Abstract: To improve the time efficiency of current vitreoretinal surgical procedures and to enable new procedures demanding increased accuracy, a robotic system to assist in vitreoretinal procedures has been developed, extending human capabilities beyond current limitations. The robotic master–slave system is compact, lightweight and easy to set up. A combination of high-precision mechanical design and high-performance controller synthesis facilitates high accuracy down to 10 μm, tremor filtering, motion scaling, automated instrument changing an ergonomic body posture for the surgeon and haptic feedback. First functional tests with the demonstrator system show a short setup time, an intuitive usage and good ergonomics. With a knife and a pick, a successful peel of the inner shell membrane of the chorioallantoic membrane of a chicken egg has been achieved.

Robotic Assisted Cannulation of Occluded Retinal Veins

Purpose To develop a methodology for cannulating porcine retinal venules using a robotic assistive arm after inducing a retinal vein occlusion using the photosensitizer rose bengal. Methodology Retinal vein occlusions proximal to the first vascular branch point were induced following intravenous injection of rose bengal by exposure to 532nm laser light delivered by slit-lamp or endolaser probe. Retinal veins were cannulated by positioning a glass catheter tip using a robotically controlled micromanipulator above venules with an outer diameter of 80μm or more and performing a preset piercing maneuver, controlled robotically. The ability of a balanced salt (BSS) solution to remove an occlusion by repeat distention of the retinal vein was also assessed. Results Cannulation using the preset piercing program was successful in 9 of 9 eyes. Piercing using the micromanipulator under manual control was successful in only 24 of 52 attempts, with several attempts leading to double piercing. The best location for cannulation was directly proximal to the occlusion. Infusion of BSS did not result in the resolution of the occlusion. Conclusion Cannulation of venules using a robotic microassistive arm can be achieved with consistency, provided the piercing is robotically driven. The model appears robust enough to allow testing of therapeutic strategies aimed at eliminating a retinal vein thrombus and its evolution over time.

Low-complexity approximations of PWA functions: A case study on Adaptive Cruise Control

This paper applies recently developed techniques for the PieceWise-Affine (PWA) approximation of explicit Model Predictive Control (MPC) to an Adaptive Cruise Control system. The optimal MPC law is approximated by using a particular class of PWA functions defined over a domain partitioned into simplices, referred to as PieceWise-Affine Simplicial functions. This approximation technique allows a very fast circuit implementation of the control function, thereby enabling the usage of MPC in embedded systems with extremely small sampling periods.

Modelling and LPV control of an electro-hydraulic servo system

This paper aims to show the modelling and control of an hydraulic servo system, targeting at frequency domain based controller design and the implementation of a LPV controller. The actual set-up consists of a mass, moved by a hydraulic cylinder and an electro-hydraulic servo valve. A nonlinear parametric model of the system, a number of fitted linear black box models as well as a LPV model combining these fits have been determined. In discretization of the control strategies for implementation on a digital control system, a new discretization algorithm is derived for LPV structures. Simulations and experimental results indicate the potential benefits of a position dependent controller over a classical controller, but show the limitations as well.

Release of experimental retinal vein occlusions by direct intraluminal injection of ocriplasmin.

Purpose Retinal vein occlusions (RVO) are a major cause of vision loss in people aged 50 years and older. Current therapeutic options limit the consequences of RVO but do not eliminate the cause. Cannulation of the involved vessel and removal of the clot may provide a more permanent solution with a less demanding follow-up. However, cannulation of smaller retinal veins remains challenging. This paper explores the use of ocriplasmin (recombinant plasmin without its kringles) to clear RVO, using a robotic micromanipulator. Methods Branch RVO were induced in a porcine model with rose bengal followed by 532 nm endolaser to the superior venous branch of the optic nerve. The vein was cannulated proximal to the occlusion or beyond the first branching vessel from the obstruction. The vein was infused with a physiologic citric acid buffer solution (CAM) or CAM/ocriplasmin. The time of cannulation, number of attempts, and the ability to release the thrombus were recorded. Results Cannulation and infusion was possible in all the cases. The use of a micromanipulator allowed for a consistent cannulation of the retinal vein and positional stability allowed the vein to remain cannulated for up to 20 min. In none of the attempts (5/5) with CAM did the thrombus dissolve, despite repeat infusion/relaxation cycles. In 7/7 injections of CAM/ocriplasmin near to the point of obstruction, the clot started to dissolve within a few minutes of injection. An infusion, attempted beyond the first venous branch point proximal to the clot, was unsuccessful in 2/3 attempts. Conclusions Ocriplasmin is effective in resolving RVO if injected close to the site of occlusion with the use of a micromanipulator.

First-in-human study of the safety and viability of intraocular robotic surgery

Microsurgery of the retina would be dramatically improved by instruments that offer supra-human precision. Here, we report the results of a first-in-human study of remotely controlled robot-assisted retinal surgery performed through a telemanipulation device. Specifically, 12 patients that required dissection of the epiretinal or inner limiting membrane over the macula were randomly assigned to either undergo robot-assisted surgery or manual surgery, under general anaesthesia. We evaluated surgical success, the duration of surgery and the amount of retinal microtrauma as a proxy for safety. Surgical outcomes were equally successful in the robotic surgery and manual surgery groups. Differences in the amount of retinal microtrauma between the two groups were statistically insignificant, yet dissection took longer with robotic surgery (median time: 4 min 55 s) than with manual surgery (1 min 20 s). We also show the feasibility of using the robot to inject recombinant tissue plasminogen activator under the retina to displace sight-threatening haemorrhage in three patients under local anaesthesia. A safe and viable robotic system for intraocular surgery would enable precise and minimally traumatic delivery of gene therapy or cell therapy to the retina.A first-in-man study of robotic-assisted intraocular surgery shows the feasibility and safety of the robotic device for the peeling of retinal membranes and for the injection of a therapeutic under the retina.

Motion Planning for Mobile Robots: A Method for the Selection of a Combination of Motion-Planning Algorithms

A motion planner for mobile robots is commonly built out of a number of algorithms that solve the two steps of motion planning: 1) representing the robot and its environment and 2) searching a path through the represented environment. However, the available literature on motion planning lacks a generic methodology to arrive at a combination of representations and search algorithm classes for a practical application. This article presents a method to select appropriate algorithm classes that solve both the steps of motion planning and to select a suitable approach to combine those algorithm classes. The method is verified by comparing its outcome with three different motion planners that have been successfully applied on robots in practice.

Tech United Eindhoven, Winner RoboCup 2014 MSL

In this paper we discuss improvements in mechanical, electrical and software design, which we did to become RoboCup 2014 world champion. Regarding hardware and control our progress includes first steps towards improved passing accuracy via velocity feedback control on the shooting lever. In terms of intelligent gameplay we have worked on creating possibilities for in-game optimization of strategic decisions. Via qr-code detection we can pass coaching instructions to our robots and with a basic machine learning algorithm success and failure after free-kicks is taken into account. In the final part of this paper we briefly discuss progress we have made in designing a four-wheeled soccer robot with a suspension system.

Frequency-domain mapping approach of stability bounds for loop shaping of bilateral controllers

Bilateral control architectures include multiple control elements. In general, the relation between a single control element and the stability of the entire system is non-linear. Therefore, stability is standard evaluated a posteriori, rendering the control design process to be complex and highly iterative. A priori understanding of stability constraints would simplify the design of control elements and, as performance is fundamentally limited by stability, could provide specific guidelines whether and how performance of the bilateral teleoperation system can be optimized. This paper presents a numerical visualization method that enables stability-based control design using classical loopshaping techniques: Frequency-domain Mapping of Bilateral Stability (FMBS). Unlike current stability-based control design approaches, the FMBS method i) is not limited to a fixed control element, a fixed control architecture or system dynamics and ii) enables the implementation of all often used stability criteria. The advantages of the FMBS method are theoretically validated through the use of two test cases, extracted from literature. Using the FMBS method, it is shown that control elements can be redesigned to achieve superior performance.